diff --git a/Cargo.lock b/Cargo.lock
index 122e578dc..0e669a4f8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6705,6 +6705,7 @@ dependencies = [
 name = "yoi-e2e"
 version = "0.0.0"
 dependencies = [
+ "chrono",
  "libc",
  "reqwest",
  "serde",
@@ -6714,6 +6715,7 @@ dependencies = [
  "tempfile",
  "webauthn-authenticator-rs",
  "webauthn-rs-proto",
+ "yoi-workspace-server",
 ]
 
 [[package]]
diff --git a/crates/server-api/src/lib.rs b/crates/server-api/src/lib.rs
index 1e30192d7..dc082acd2 100644
--- a/crates/server-api/src/lib.rs
+++ b/crates/server-api/src/lib.rs
@@ -4025,6 +4025,17 @@ impl RequestActor {
 #[serde(deny_unknown_fields)]
 pub struct WhoamiResponse {
     pub actor: Option<RequestActor>,
+    pub session: BrowserSessionState,
+}
+
+/// Browser navigation evidence, not an authorization grant or a generic 401 classification.
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, JsonSchema)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[serde(tag = "kind", rename_all = "snake_case", deny_unknown_fields)]
+pub enum BrowserSessionState {
+    Anonymous {},
+    Authenticated { expires_at: Option<String> },
+    Expired {},
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, JsonSchema)]
@@ -11533,6 +11544,7 @@ pub fn auth_api_typescript() -> String {
         ActorAuthMethod::decl(&config),
         AuthenticatedUser::decl(&config),
         RequestActor::decl(&config),
+        BrowserSessionState::decl(&config),
         WhoamiResponse::decl(&config),
         AuthBootstrapUserRequest::decl(&config),
         AuthUserResponse::decl(&config),
@@ -13961,7 +13973,8 @@ mod tests {
                 "handle": "hare",
                 "display_name": "Hare",
                 "auth_method": "browser_session"
-            }
+            },
+            "session": { "kind": "authenticated", "expires_at": "2026-10-20T00:00:00Z" }
         });
         let decoded = serde_json::from_value::<WhoamiResponse>(whoami.clone())
             .expect("server whoami fixture should match shared DTO");
@@ -14143,11 +14156,36 @@ mod tests {
 
         let unexpected_field = serde_json::json!({
             "actor": null,
+            "session": { "kind": "anonymous" },
             "access_token": "must-not-be-accepted"
         });
         assert!(serde_json::from_value::<WhoamiResponse>(unexpected_field).is_err());
     }
 
+    #[test]
+    fn whoami_session_json_distinguishes_anonymous_expired_and_token_auth() {
+        for session in [
+            serde_json::json!({"kind":"anonymous"}),
+            serde_json::json!({"kind":"expired"}),
+            serde_json::json!({"kind":"authenticated", "expires_at":null}),
+        ] {
+            let value = serde_json::json!({"actor":null, "session":session});
+            let response: WhoamiResponse = serde_json::from_value(value.clone()).unwrap();
+            assert_eq!(serde_json::to_value(response).unwrap(), value);
+        }
+        for session in [
+            serde_json::json!({"kind":"unknown"}),
+            serde_json::json!({"kind":"expired", "expires_at":null}),
+        ] {
+            assert!(
+                serde_json::from_value::<WhoamiResponse>(
+                    serde_json::json!({"actor":null, "session":session})
+                )
+                .is_err()
+            );
+        }
+    }
+
     #[test]
     fn device_login_debug_output_redacts_secret_material() {
         let start = DeviceLoginStartResponse {
diff --git a/crates/workspace-server/src/auth.rs b/crates/workspace-server/src/auth.rs
index fc6a302fe..c46c54926 100644
--- a/crates/workspace-server/src/auth.rs
+++ b/crates/workspace-server/src/auth.rs
@@ -91,11 +91,38 @@ pub fn parse_bearer(headers: &HeaderMap) -> Option<String> {
 }
 
 pub fn parse_cookie(headers: &HeaderMap, cookie_name: &str) -> Option<String> {
-    let cookie_header = headers.get(header::COOKIE)?.to_str().ok()?;
-    cookie_header.split(';').find_map(|pair| {
-        let (name, value) = pair.trim().split_once('=')?;
-        (name == cookie_name && !value.is_empty()).then(|| value.to_string())
-    })
+    unique_cookie(headers, cookie_name)
+        .ok()
+        .flatten()
+        .filter(|value| !value.is_empty())
+}
+
+// Cookie has no path/domain metadata on requests. Duplicates (including identical values
+// and multiple Cookie headers) cannot be disambiguated safely after cookie tossing.
+fn unique_cookie(
+    headers: &HeaderMap,
+    cookie_name: &str,
+) -> std::result::Result<Option<String>, ()> {
+    let mut found = None;
+    for header in headers.get_all(header::COOKIE) {
+        let header = header.to_str().map_err(|_| ())?;
+        for pair in header.split(';') {
+            let pair = pair.trim();
+            let Some((name, value)) = pair.split_once('=') else {
+                if pair == cookie_name {
+                    return Err(());
+                }
+                continue;
+            };
+            if name == cookie_name {
+                if found.is_some() {
+                    return Err(());
+                }
+                found = Some(value.to_owned());
+            }
+        }
+    }
+    Ok(found)
 }
 
 pub async fn resolve_request_actor(
@@ -121,6 +148,14 @@ pub(crate) fn resolve_request_actor_sync(
     bearer: Option<String>,
     session: Option<String>,
 ) -> Result<Option<RequestActor>> {
+    Ok(resolve_credentials_sync(store, bearer, session)?.map(|(actor, _)| actor))
+}
+
+fn resolve_credentials_sync(
+    store: &dyn ControlPlaneStore,
+    bearer: Option<String>,
+    session: Option<String>,
+) -> Result<Option<(RequestActor, Option<String>)>> {
     if let Some(token) = bearer {
         let token_hash = token_hash(&token);
         if let Some(api_token) = store.resolve_api_token(&token_hash)? {
@@ -132,7 +167,10 @@ pub(crate) fn resolve_request_actor_sync(
                 return Ok(None);
             }
             store.mark_api_token_used(&token_hash, &now_rfc3339())?;
-            return actor_for_user(store, &api_token.user_id, ActorAuthMethod::ApiToken);
+            return Ok(
+                actor_for_user(store, &api_token.user_id, ActorAuthMethod::ApiToken)?
+                    .map(|actor| (actor, None)),
+            );
         }
     }
 
@@ -141,13 +179,95 @@ pub(crate) fn resolve_request_actor_sync(
             if is_expired(&session.expires_at) {
                 return Ok(None);
             }
-            return actor_for_user(store, &session.user_id, ActorAuthMethod::BrowserSession);
+            return Ok(
+                actor_for_user(store, &session.user_id, ActorAuthMethod::BrowserSession)?
+                    .map(|actor| (actor, Some(session.expires_at))),
+            );
         }
     }
 
     Ok(None)
 }
 
+// This marker is a non-authenticating reference to the existing non-revoked session row.
+// It outlives the auth cookie so Max-Age expiry remains distinguishable from a new browser.
+// No second session store is introduced; clearing all cookies necessarily loses this evidence.
+// Keep the established 14-day authentication lifetime. The additional week is only a bounded
+// return-navigation window (including a week away); it never extends authentication. The store
+// reclaims expired rows past this same boundary on subsequent session issuance. Neither whoami
+// nor other reads refresh the marker or the row's absolute expiry.
+pub const BROWSER_SESSION_SECONDS: i64 = 14 * 24 * 60 * 60;
+pub const SESSION_EXPIRY_GRACE_SECONDS: i64 = 7 * 24 * 60 * 60;
+
+pub fn session_marker_cookie_name(cookie_name: &str) -> String {
+    format!("{cookie_name}_expiry")
+}
+
+pub async fn resolve_whoami(
+    store: std::sync::Arc<dyn ControlPlaneStore>,
+    headers: &HeaderMap,
+    cookie_name: &str,
+) -> Result<server_api::WhoamiResponse> {
+    let bearer = parse_bearer(headers);
+    // Even an empty/invalid auth cookie takes precedence over an older marker.
+    // An ambiguous primary is invalid, not absent; never fall back to an older marker.
+    let session = unique_cookie(headers, cookie_name).unwrap_or_else(|()| Some(String::new()));
+    let marker = parse_cookie(headers, &session_marker_cookie_name(cookie_name));
+    let executor = store.db_executor();
+    executor
+        .run(move || resolve_whoami_sync(store.as_ref(), bearer, session, marker))
+        .await
+}
+
+fn resolve_whoami_sync(
+    store: &dyn ControlPlaneStore,
+    bearer: Option<String>,
+    session_token: Option<String>,
+    marker: Option<String>,
+) -> Result<server_api::WhoamiResponse> {
+    use server_api::{BrowserSessionState, WhoamiResponse};
+    let anonymous = || WhoamiResponse {
+        actor: None,
+        session: BrowserSessionState::Anonymous {},
+    };
+    // Preserve the existing API-token precedence and fallback rules, including expired tokens.
+    if let Some((actor, expires_at)) =
+        resolve_credentials_sync(store, bearer, session_token.clone())?
+    {
+        return Ok(WhoamiResponse {
+            actor: Some(actor),
+            session: BrowserSessionState::Authenticated { expires_at },
+        });
+    }
+    let hash = match session_token {
+        Some(token) => token_hash(&token),
+        None => match marker {
+            Some(hash) => hash,
+            None => return Ok(anonymous()),
+        },
+    };
+    let Some(session) = store.resolve_browser_session(&hash)? else {
+        return Ok(anonymous());
+    };
+    if store.get_user(&session.user_id)?.is_none() {
+        return Ok(anonymous());
+    }
+    if within_session_expiry_grace(&session.expires_at, Utc::now()) {
+        return Ok(WhoamiResponse {
+            actor: None,
+            session: BrowserSessionState::Expired {},
+        });
+    }
+    // A marker for a still-valid session cannot restore authentication after partial deletion.
+    Ok(anonymous())
+}
+
+fn within_session_expiry_grace(expires_at: &str, now: DateTime<Utc>) -> bool {
+    DateTime::parse_from_rfc3339(expires_at).is_ok_and(|expires_at| {
+        expires_at <= now && now < expires_at + Duration::seconds(SESSION_EXPIRY_GRACE_SECONDS)
+    })
+}
+
 fn actor_for_user<S: ControlPlaneStore + ?Sized>(
     store: &S,
     user_id: &str,
@@ -274,6 +394,13 @@ mod tests {
             .unwrap();
         assert_eq!(actor.user_id, "user-auth");
         assert_eq!(actor.auth_method, ActorAuthMethod::ApiToken);
+        let whoami = resolve_whoami(store.clone(), &headers, "session")
+            .await
+            .unwrap();
+        assert_eq!(
+            whoami.session,
+            server_api::BrowserSessionState::Authenticated { expires_at: None }
+        );
         assert!(
             store
                 .resolve_api_token(&hash)
@@ -363,20 +490,119 @@ mod tests {
         assert!(futures::poll!(queued.as_mut()).is_pending());
         let mut headers = HeaderMap::new();
         headers.insert(header::COOKIE, "session=session-secret".parse().unwrap());
+        let actor_result = tokio::time::timeout(
+            std::time::Duration::from_secs(1),
+            resolve_request_actor(store.clone(), &headers, "session"),
+        )
+        .await;
         let result = tokio::time::timeout(
             std::time::Duration::from_secs(1),
-            resolve_request_actor(store, &headers, "session"),
+            resolve_whoami(store, &headers, "session"),
         )
         .await;
         release.send(()).unwrap();
         blocker.await.unwrap().unwrap();
         queued.await.unwrap();
+        assert!(matches!(
+            actor_result.expect("actor lookup rejects capacity"),
+            Err(Error::DbCapacityExceeded)
+        ));
         assert!(matches!(
             result.expect("capacity rejection must not wait for queued SQL"),
             Err(Error::DbCapacityExceeded)
         ));
     }
 
+    #[tokio::test]
+    async fn whoami_classifies_only_live_store_backed_session_expiry() {
+        use server_api::BrowserSessionState;
+        let store = seeded_store();
+        for (secret, offset, revoked) in [
+            ("recent", -60, false),
+            ("old", -SESSION_EXPIRY_GRACE_SECONDS - 60, false),
+            ("revoked", -60, true),
+        ] {
+            store
+                .create_browser_session(&BrowserSessionRecord {
+                    session_id: format!("session-{secret}"),
+                    token_hash: token_hash(secret),
+                    user_id: "user-auth".into(),
+                    created_at: "1".into(),
+                    expires_at: rfc3339_after(Duration::seconds(offset)),
+                    revoked_at: revoked.then(|| now_rfc3339()),
+                })
+                .unwrap();
+        }
+        let cases = [
+            (String::new(), BrowserSessionState::Anonymous {}),
+            ("session=unknown".into(), BrowserSessionState::Anonymous {}),
+            ("session=recent".into(), BrowserSessionState::Expired {}),
+            (
+                format!("session_expiry={}", token_hash("recent")),
+                BrowserSessionState::Expired {},
+            ),
+            (
+                format!("session_expiry={}", token_hash("session-secret")),
+                BrowserSessionState::Anonymous {},
+            ),
+            (
+                "session_expiry=unknown".into(),
+                BrowserSessionState::Anonymous {},
+            ),
+            (
+                "session_expiry=recent".into(),
+                BrowserSessionState::Anonymous {},
+            ),
+            (
+                format!("session=unknown; session_expiry={}", token_hash("recent")),
+                BrowserSessionState::Anonymous {},
+            ),
+            (
+                format!("session=; session_expiry={}", token_hash("recent")),
+                BrowserSessionState::Anonymous {},
+            ),
+            ("session=revoked".into(), BrowserSessionState::Anonymous {}),
+            (
+                format!("session_expiry={}", token_hash("revoked")),
+                BrowserSessionState::Anonymous {},
+            ),
+            ("session=old".into(), BrowserSessionState::Anonymous {}),
+            (
+                format!("session_expiry={}", token_hash("old")),
+                BrowserSessionState::Anonymous {},
+            ),
+            (
+                format!(
+                    "session=session-secret; session_expiry={}",
+                    token_hash("recent")
+                ),
+                BrowserSessionState::Authenticated {
+                    expires_at: Some("9999-01-01T00:00:00Z".into()),
+                },
+            ),
+        ];
+        for (cookie, expected) in cases {
+            let mut headers = HeaderMap::new();
+            headers.insert(header::COOKIE, cookie.parse().unwrap());
+            let response = resolve_whoami(store.clone(), &headers, "session")
+                .await
+                .unwrap();
+            assert_eq!(response.session, expected, "cookie: {cookie}");
+            assert_eq!(
+                response.actor.is_some(),
+                matches!(expected, BrowserSessionState::Authenticated { .. })
+            );
+            if !matches!(expected, BrowserSessionState::Authenticated { .. }) {
+                assert!(
+                    resolve_request_actor(store.clone(), &headers, "session")
+                        .await
+                        .unwrap()
+                        .is_none()
+                );
+            }
+        }
+    }
+
     #[test]
     fn user_code_uses_the_uuid_random_tail() {
         let id = Uuid::parse_str("01234567-89ab-7cde-8123-456789abcdef").expect("UUID");
@@ -395,4 +621,136 @@ mod tests {
         );
         assert_eq!(code, code.to_ascii_uppercase());
     }
+
+    #[test]
+    fn expiry_grace_includes_expiry_but_excludes_its_absolute_end() {
+        let expiry = DateTime::parse_from_rfc3339("2026-01-01T00:00:00Z")
+            .unwrap()
+            .with_timezone(&Utc);
+        for (offset, expected) in [
+            (-1, false),
+            (0, true),
+            (SESSION_EXPIRY_GRACE_SECONDS - 1, true),
+            (SESSION_EXPIRY_GRACE_SECONDS, false),
+        ] {
+            assert_eq!(
+                within_session_expiry_grace(
+                    &expiry.to_rfc3339(),
+                    expiry + Duration::seconds(offset)
+                ),
+                expected
+            );
+        }
+        assert!(!within_session_expiry_grace("invalid", expiry));
+    }
+
+    #[tokio::test]
+    async fn duplicate_cookies_never_select_an_actor_or_promote_an_ambiguous_marker() {
+        use server_api::BrowserSessionState;
+        let store = seeded_store();
+        let expired_hash = token_hash("expired-duplicate");
+        store
+            .create_browser_session(&BrowserSessionRecord {
+                session_id: "expired-duplicate".into(),
+                token_hash: expired_hash.clone(),
+                user_id: "user-auth".into(),
+                created_at: now_rfc3339(),
+                expires_at: rfc3339_after(Duration::seconds(-60)),
+                revoked_at: None,
+            })
+            .unwrap();
+        for cookies in [
+            vec!["session=session-secret; session=unknown".to_owned()],
+            vec!["session=session-secret; session=session-secret".to_owned()],
+            vec![
+                "session=session-secret".to_owned(),
+                "session=unknown".to_owned(),
+            ],
+            vec![format!(
+                "session=; session=session-secret; session_expiry={expired_hash}"
+            )],
+            vec![format!(
+                "session_expiry={expired_hash}; session_expiry={expired_hash}"
+            )],
+            vec![format!("session; session_expiry={expired_hash}")],
+        ] {
+            let mut headers = HeaderMap::new();
+            for cookie in cookies {
+                headers.append(header::COOKIE, cookie.parse().unwrap());
+            }
+            assert!(
+                resolve_request_actor(store.clone(), &headers, "session")
+                    .await
+                    .unwrap()
+                    .is_none()
+            );
+            assert_eq!(
+                resolve_whoami(store.clone(), &headers, "session")
+                    .await
+                    .unwrap()
+                    .session,
+                BrowserSessionState::Anonymous {}
+            );
+        }
+        let mut headers = HeaderMap::new();
+        headers.insert(
+            header::COOKIE,
+            format!("session=session-secret; session_expiry={expired_hash}")
+                .parse()
+                .unwrap(),
+        );
+        assert!(matches!(
+            resolve_whoami(store, &headers, "session")
+                .await
+                .unwrap()
+                .session,
+            BrowserSessionState::Authenticated { .. }
+        ));
+    }
+
+    #[test]
+    fn session_issuance_reclaims_only_rows_beyond_recovery_grace() {
+        let store = seeded_store();
+        let record = |secret: &str, offset| BrowserSessionRecord {
+            session_id: secret.into(),
+            token_hash: token_hash(secret),
+            user_id: "user-auth".into(),
+            created_at: now_rfc3339(),
+            expires_at: rfc3339_after(Duration::seconds(offset)),
+            revoked_at: None,
+        };
+        store
+            .create_browser_session(&record("past-grace", -SESSION_EXPIRY_GRACE_SECONDS - 60))
+            .unwrap();
+        assert!(
+            store
+                .resolve_browser_session(&token_hash("past-grace"))
+                .unwrap()
+                .is_some()
+        );
+        store
+            .create_browser_session(&record("within-grace", -SESSION_EXPIRY_GRACE_SECONDS + 60))
+            .unwrap();
+        assert!(
+            store
+                .resolve_browser_session(&token_hash("past-grace"))
+                .unwrap()
+                .is_none()
+        );
+        store
+            .create_browser_session(&record("new-session", BROWSER_SESSION_SECONDS))
+            .unwrap();
+        assert!(
+            store
+                .resolve_browser_session(&token_hash("within-grace"))
+                .unwrap()
+                .is_some()
+        );
+        assert!(
+            store
+                .resolve_browser_session(&token_hash("new-session"))
+                .unwrap()
+                .is_some()
+        );
+    }
 }
diff --git a/crates/workspace-server/src/server.rs b/crates/workspace-server/src/server.rs
index dd256fea9..30732afac 100644
--- a/crates/workspace-server/src/server.rs
+++ b/crates/workspace-server/src/server.rs
@@ -6856,6 +6856,7 @@ async fn attach_server_request_context(
 }
 
 fn generated_auth_contract_router(service: ServerApiContractService) -> Router {
+    let auth = auth_public_config(&service.auth_api().config);
     let service = Arc::new(service);
     let origin_context = Router::new()
         .merge(server_api::server_api_axum::auth_activation_options(
@@ -6887,7 +6888,6 @@ fn generated_auth_contract_router(service: ServerApiContractService) -> Router {
         .merge(server_api::server_api_axum::auth_device_login_approve(
             service.clone(),
         ))
-        .merge(server_api::server_api_axum::auth_whoami(service.clone()))
         .layer(middleware::from_fn_with_state(
             service.as_ref().clone(),
             attach_server_request_context,
@@ -6908,12 +6908,20 @@ fn generated_auth_contract_router(service: ServerApiContractService) -> Router {
             service.clone(),
         ))
         .merge(server_api::server_api_axum::auth_logout(service.clone()))
+        .merge(
+            server_api::server_api_axum::auth_whoami(service.clone())
+                .layer(middleware::from_fn(attach_server_origin_context)),
+        )
         .merge(server_api::server_api_axum::auth_device_login_start(
             service.clone(),
         ))
         .merge(server_api::server_api_axum::auth_device_login_poll(service))
         .merge(origin_context)
         .merge(actor_context)
+        .layer(middleware::from_fn_with_state(
+            auth,
+            append_session_marker_cookie,
+        ))
         .layer(middleware::map_response(
             |mut response: Response| async move {
                 // Current role/policy and authentication responses must not be cached
@@ -6926,6 +6934,62 @@ fn generated_auth_contract_router(service: ServerApiContractService) -> Router {
         ))
 }
 
+// The typed auth operations expose one Set-Cookie. At the HTTP boundary, pair only a real
+// session Set-Cookie with a non-authenticating expiry marker, including login and logout.
+// Mirroring its attributes keeps Secure/Path/Domain/SameSite aligned without a second policy.
+async fn append_session_marker_cookie(
+    State(auth): State<AuthPublicConfig>,
+    request: Request,
+    next: Next,
+) -> Response {
+    let mut response = next.run(request).await;
+    let marker = response
+        .headers()
+        .get_all(axum::http::header::SET_COOKIE)
+        .iter()
+        .find_map(|value| {
+            let value = value.to_str().ok()?;
+            let (pair, attributes) = value.split_once(';')?;
+            let (name, token) = pair.split_once('=')?;
+            if name != auth.cookie_name {
+                return None;
+            }
+            let max_age = attributes
+                .split(';')
+                .find_map(|attr| attr.trim().strip_prefix("Max-Age=")?.parse::<i64>().ok())?;
+            let (hash, marker_age) = if max_age <= 0 {
+                (String::new(), 0)
+            } else {
+                (
+                    token_hash(token),
+                    max_age + crate::auth::SESSION_EXPIRY_GRACE_SECONDS,
+                )
+            };
+            let attributes = attributes
+                .split(';')
+                .map(|attr| {
+                    if attr.trim().starts_with("Max-Age=") {
+                        format!(" Max-Age={marker_age}")
+                    } else {
+                        attr.to_owned()
+                    }
+                })
+                .collect::<Vec<_>>()
+                .join(";");
+            HeaderValue::from_str(&format!(
+                "{}={hash};{attributes}",
+                crate::auth::session_marker_cookie_name(name)
+            ))
+            .ok()
+        });
+    if let Some(marker) = marker {
+        response
+            .headers_mut()
+            .append(axum::http::header::SET_COOKIE, marker);
+    }
+    response
+}
+
 fn generated_workspace_catalog_contract_router(service: ServerApiContractService) -> Router {
     let service = Arc::new(service);
     Router::new()
@@ -8151,9 +8215,15 @@ impl server_api::ServerApi for ServerApiContractService {
         &self,
         context: server_api::ServerRequestContext,
     ) -> std::result::Result<WhoamiResponse, server_api::RepositoryApiError> {
-        Ok(WhoamiResponse {
-            actor: context.actor,
-        })
+        let headers = contract_request_headers(&context)?;
+        let api = self.auth_api();
+        crate::auth::resolve_whoami(
+            api.store.clone(),
+            &headers,
+            &auth_public_config(&api.config).cookie_name,
+        )
+        .await
+        .map_err(|error| ApiError::from(error).into_repository_api_error())
     }
 
     async fn auth_logout(
@@ -30307,14 +30377,14 @@ fn issue_browser_session(
         token_hash: token_hash(&session_token),
         user_id: user.user_id.clone(),
         created_at: crate::auth::now_rfc3339(),
-        expires_at: rfc3339_after(Duration::days(14)),
+        expires_at: rfc3339_after(Duration::seconds(crate::auth::BROWSER_SESSION_SECONDS)),
         revoked_at: None,
     })?;
     let auth = auth_public_config(&api.config);
     let cookie = session_set_cookie(
         session_cookie_policy(&auth),
         &session_token,
-        14 * 24 * 60 * 60,
+        crate::auth::BROWSER_SESSION_SECONDS,
     );
     Ok((
         AuthUserResponse {
@@ -30510,6 +30580,16 @@ fn logout_browser_session(
             .store
             .revoke_browser_session(&token_hash(&session_token), &crate::auth::now_rfc3339())?;
     }
+    // A missing auth cookie after Max-Age must not prevent explicit logout from revoking
+    // the recovery reference. This hash is never accepted as an authentication credential.
+    if let Some(hash) = parse_cookie(
+        &headers,
+        &crate::auth::session_marker_cookie_name(&auth.cookie_name),
+    ) {
+        let _ = api
+            .store
+            .revoke_browser_session(&hash, &crate::auth::now_rfc3339())?;
+    }
     Ok((
         LogoutResponse {
             status: LogoutStatus::LoggedOut,
@@ -53509,6 +53589,7 @@ mod tests {
             .await
             .unwrap();
         assert_eq!(registration_response.status(), StatusCode::OK);
+        assert_auth_response_has_expiry_marker(registration_response.headers(), &cookie_name);
         let registration_cookie = registration_response
             .headers()
             .get(axum::http::header::SET_COOKIE)
@@ -53546,6 +53627,12 @@ mod tests {
                 .unwrap(),
         )
         .unwrap();
+        assert_eq!(registered_whoami["session"]["kind"], "authenticated");
+        assert!(
+            registered_whoami["session"]["expires_at"]
+                .as_str()
+                .is_some()
+        );
         assert_eq!(
             registered_whoami["actor"]["handle"],
             "generated-passkey-user"
@@ -53600,6 +53687,7 @@ mod tests {
             .await
             .unwrap();
         assert_eq!(login_response.status(), StatusCode::OK);
+        assert_auth_response_has_expiry_marker(login_response.headers(), &cookie_name);
         let login_cookie = login_response
             .headers()
             .get(axum::http::header::SET_COOKIE)
@@ -53684,6 +53772,169 @@ mod tests {
         assert!(logged_out_whoami["actor"].is_null());
     }
 
+    // Real generated auth routes, DB executor and SQLite; no auth resolution is mocked.
+    #[tokio::test]
+    async fn whoami_expiry_marker_survives_auth_cookie_loss_but_logout_revokes_it() {
+        let workspace = tempfile::tempdir().unwrap();
+        let api = test_api(workspace.path()).await;
+        seed_test_api_token(api.store.as_ref(), "expiry-router");
+        let user = api.store.get_user("user-expiry-router").unwrap().unwrap();
+        let auth = auth_public_config(&api.config);
+        let cookie_name = auth.cookie_name;
+        let hash = token_hash("expired-router-secret");
+        api.store
+            .create_browser_session(&BrowserSessionRecord {
+                session_id: "expired-router-session".into(),
+                token_hash: hash.clone(),
+                user_id: user.user_id,
+                created_at: crate::auth::now_rfc3339(),
+                expires_at: rfc3339_after(Duration::minutes(-1)),
+                revoked_at: None,
+            })
+            .unwrap();
+        let marker = format!(
+            "{}={hash}",
+            crate::auth::session_marker_cookie_name(&cookie_name)
+        );
+        let app = generated_auth_contract_router(ServerApiContractService::Workspace(api.clone()));
+        for (cookie, kind) in [
+            (String::new(), "anonymous"),
+            (format!("{cookie_name}=expired-router-secret"), "expired"),
+            (marker.clone(), "expired"),
+        ] {
+            let response = app
+                .clone()
+                .oneshot(
+                    Request::builder()
+                        .uri("/api/auth/whoami")
+                        .header(axum::http::header::COOKIE, cookie)
+                        .body(Body::empty())
+                        .unwrap(),
+                )
+                .await
+                .unwrap();
+            assert_eq!(response.status(), StatusCode::OK);
+            assert_eq!(response.headers()[CACHE_CONTROL], "no-store");
+            assert!(
+                !response
+                    .headers()
+                    .contains_key(axum::http::header::SET_COOKIE)
+            );
+            let value: Value =
+                serde_json::from_slice(&to_bytes(response.into_body(), usize::MAX).await.unwrap())
+                    .unwrap();
+            assert_eq!(value["actor"], Value::Null);
+            assert_eq!(value["session"]["kind"], kind);
+        }
+        let denied = app
+            .clone()
+            .oneshot(
+                Request::builder()
+                    .method(Method::POST)
+                    .uri("/api/auth/passkeys/addition/options")
+                    .header(axum::http::header::COOKIE, &marker)
+                    .header(ORIGIN, &auth.origin)
+                    .header(CONTENT_TYPE, "application/json")
+                    .body(Body::from("{}"))
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        // Preserve the operation's existing auth_required/403 contract; no HTML redirect.
+        assert_eq!(denied.status(), StatusCode::FORBIDDEN);
+        assert!(!denied.headers().contains_key(axum::http::header::LOCATION));
+        let logout = app
+            .clone()
+            .oneshot(
+                Request::builder()
+                    .method(Method::POST)
+                    .uri("/api/auth/logout")
+                    .header(axum::http::header::COOKIE, &marker)
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(logout.status(), StatusCode::OK);
+        let cleared: Vec<_> = logout
+            .headers()
+            .get_all(axum::http::header::SET_COOKIE)
+            .iter()
+            .map(|v| v.to_str().unwrap())
+            .collect();
+        assert_eq!(cleared.len(), 2);
+        assert!(
+            cleared
+                .iter()
+                .all(|value| value.contains("Max-Age=0") && value.contains("HttpOnly"))
+        );
+        assert!(cleared.iter().any(|value| value.starts_with(&format!(
+            "{}=;",
+            crate::auth::session_marker_cookie_name(&cookie_name)
+        ))));
+        assert!(api.store.resolve_browser_session(&hash).unwrap().is_none());
+        let response = app
+            .oneshot(
+                Request::builder()
+                    .uri("/api/auth/whoami")
+                    .header(axum::http::header::COOKIE, marker)
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        let value: Value =
+            serde_json::from_slice(&to_bytes(response.into_body(), usize::MAX).await.unwrap())
+                .unwrap();
+        assert_eq!(value["session"]["kind"], "anonymous");
+    }
+
+    fn assert_auth_response_has_expiry_marker(headers: &HeaderMap, cookie_name: &str) {
+        let cookies: Vec<_> = headers
+            .get_all(axum::http::header::SET_COOKIE)
+            .iter()
+            .map(|value| value.to_str().unwrap())
+            .collect();
+        let auth = cookies
+            .iter()
+            .find(|value| value.starts_with(&format!("{cookie_name}=")))
+            .unwrap();
+        let (_, token) = auth.split(';').next().unwrap().split_once('=').unwrap();
+        let marker = cookies
+            .iter()
+            .find(|value| {
+                value.starts_with(&format!(
+                    "{}=",
+                    crate::auth::session_marker_cookie_name(cookie_name)
+                ))
+            })
+            .unwrap();
+        let expected = token_hash(token);
+        assert_eq!(
+            parse_cookie(
+                &{
+                    let mut headers = HeaderMap::new();
+                    headers.insert(axum::http::header::COOKIE, marker.parse().unwrap());
+                    headers
+                },
+                &crate::auth::session_marker_cookie_name(cookie_name)
+            ),
+            Some(expected)
+        );
+        assert!(auth.contains(&format!("Max-Age={}", crate::auth::BROWSER_SESSION_SECONDS)));
+        assert!(marker.contains(&format!(
+            "Max-Age={}",
+            crate::auth::BROWSER_SESSION_SECONDS + crate::auth::SESSION_EXPIRY_GRACE_SECONDS
+        )));
+        for attribute in ["Path=/", "HttpOnly", "SameSite=Lax", "Secure"] {
+            assert_eq!(
+                auth.contains(attribute),
+                marker.contains(attribute),
+                "{attribute}"
+            );
+        }
+    }
+
     #[tokio::test]
     async fn browser_session_set_and_clear_cookies_follow_public_https_scheme() {
         for (scheme, secure) in [("http", false), ("https", true)] {
diff --git a/crates/workspace-server/src/store.rs b/crates/workspace-server/src/store.rs
index b9dd24f8a..138b56fa6 100644
--- a/crates/workspace-server/src/store.rs
+++ b/crates/workspace-server/src/store.rs
@@ -7131,6 +7131,16 @@ impl ControlPlaneStore for SqliteWorkspaceStore {
     fn create_browser_session(&self, record: &BrowserSessionRecord) -> Result<()> {
         self.with_immediate_transaction(|conn| {
             activation::require_active(conn, &record.user_id)?;
+            // Retain the real row throughout the non-authenticating recovery window, not
+            // forever. Issuance amortizes reclamation without extending marker lifetime or
+            // introducing another store/scheduler. Inactive stores do not grow between issues.
+            let cutoff = (chrono::Utc::now()
+                - chrono::Duration::seconds(crate::auth::SESSION_EXPIRY_GRACE_SECONDS))
+                .to_rfc3339();
+            conn.execute(
+                "DELETE FROM browser_sessions WHERE julianday(expires_at) <= julianday(?1) OR julianday(expires_at) IS NULL",
+                params![cutoff],
+            )?;
             conn.execute(
                 r#"INSERT INTO browser_sessions (session_id, token_hash, user_id, created_at, expires_at, revoked_at)
                    VALUES (?1, ?2, ?3, ?4, ?5, ?6)"#,
diff --git a/openapi/server-api.json b/openapi/server-api.json
index e601f843e..138988240 100644
--- a/openapi/server-api.json
+++ b/openapi/server-api.json
@@ -443,6 +443,56 @@
         "additionalProperties": false,
         "type": "object"
       },
+      "BrowserSessionState": {
+        "description": "Browser navigation evidence, not an authorization grant or a generic 401 classification.",
+        "oneOf": [
+          {
+            "additionalProperties": false,
+            "properties": {
+              "kind": {
+                "const": "anonymous",
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind"
+            ],
+            "type": "object"
+          },
+          {
+            "additionalProperties": false,
+            "properties": {
+              "expires_at": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "kind": {
+                "const": "authenticated",
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind"
+            ],
+            "type": "object"
+          },
+          {
+            "additionalProperties": false,
+            "properties": {
+              "kind": {
+                "const": "expired",
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind"
+            ],
+            "type": "object"
+          }
+        ]
+      },
       "BrowserTicketState": {
         "enum": [
           "open",
@@ -14846,8 +14896,14 @@
                 "type": "null"
               }
             ]
+          },
+          "session": {
+            "$ref": "#/components/schemas/BrowserSessionState"
           }
         },
+        "required": [
+          "session"
+        ],
         "type": "object"
       },
       "WorkerBusyState": {
@@ -17831,7 +17887,7 @@
   "info": {
     "title": "Yoi Server API",
     "version": "0.1.0",
-    "x-yoi-source-digest": "sha256:4e01d7dd0dab015ba3204045da33d7b87c9edc166b7dad464a8ab0d61e0f0e6d"
+    "x-yoi-source-digest": "sha256:3cd508b4b2c8e82c8f185092bada8e8ec3e1d8f8f503a12775f6014765e5b45f"
   },
   "openapi": "3.1.0",
   "paths": {
diff --git a/tests/e2e/Cargo.toml b/tests/e2e/Cargo.toml
index 9638ae45a..b308eeb49 100644
--- a/tests/e2e/Cargo.toml
+++ b/tests/e2e/Cargo.toml
@@ -19,6 +19,8 @@ sha2.workspace = true
 tempfile.workspace = true
 
 [dev-dependencies]
+chrono = { version = "0.4", default-features = false, features = ["clock"] }
+yoi-workspace-server.workspace = true
 server-api.workspace = true
 webauthn-rs-proto = "0.5.5"
 webauthn-authenticator-rs = { version = "0.5.5", default-features = false, features = ["softpasskey"] }
diff --git a/tests/e2e/browser/auth_sessions.ts b/tests/e2e/browser/auth_sessions.ts
new file mode 100644
index 000000000..226ae9e76
--- /dev/null
+++ b/tests/e2e/browser/auth_sessions.ts
@@ -0,0 +1,435 @@
+/// <reference lib="dom" />
+// WorkerE2eEnvironment所有の実Backendへ全APIをproxyし、本番static shellを配信する。
+// fixture-serverと同じSPA配信方式。製品APIのwhoami、認証、認可、Set-Cookieは置換しない。
+// 固定expiry/短命cookieを作る明示fixtureだけが発行境界を代替し、実分類はBackendへ委ねる。
+// navigator.credentialsのみRustのResidentAuthenticatorへ接続する（物理認証器ではない）。
+import { assert, assertEquals } from "@std/assert";
+import { extname, join, normalize } from "@std/path";
+import { type Browser, type BrowserContext, chromium } from "playwright";
+
+const [backend, origin, build, handle] = Deno.args;
+if (!backend || !origin || !build || !handle) {
+  throw new Error(
+    "Expected isolated Backend URL, browser origin, production build, handle",
+  );
+}
+await Deno.stat(join(build, "index.html")); // 暗黙buildや別asset rootへのfallbackはしない。
+const mime: Record<string, string> = {
+  ".html": "text/html; charset=utf-8",
+  ".js": "text/javascript",
+  ".css": "text/css",
+  ".json": "application/json",
+  ".svg": "image/svg+xml",
+  ".png": "image/png",
+  ".woff2": "font/woff2",
+  ".ico": "image/x-icon",
+};
+const server = Deno.serve({
+  hostname: "127.0.0.1",
+  port: Number(new URL(origin).port),
+  onListen() {},
+}, async (request) => {
+  const url = new URL(request.url);
+  if (url.pathname === "/__e2e/expired-session" && request.method === "POST") {
+    if (request.headers.get("origin") !== origin) {
+      return new Response(null, { status: 403 });
+    }
+    // Rustは環境専用DBの実登録userへ公開store APIで保存する。secretをbody/ログへ出さない。
+    const fixture = await bridge("expired-session", {}) as {
+      set_cookies: string[];
+    };
+    const headers = new Headers({ "cache-control": "no-store" });
+    for (const cookie of fixture.set_cookies) {
+      headers.append("set-cookie", cookie);
+    }
+    return new Response(null, { status: 204, headers });
+  }
+  if (
+    url.pathname === "/__e2e/primary-cookie-present" && request.method === "GET"
+  ) {
+    // HTTPで受け取ったprimaryの有無だけを返す。値、marker、DB状態は公開しない。
+    const present = request.headers.get("cookie")?.split(";").some((pair) =>
+      pair.trim().split("=", 1)[0] === "yoi_workspace_session"
+    ) ?? false;
+    return Response.json(present, { headers: { "cache-control": "no-store" } });
+  }
+  if (url.pathname.startsWith("/api/")) {
+    const headers = new Headers(request.headers);
+    headers.delete("host");
+    headers.delete("connection");
+    // OriginとCookieを保持し、Set-Cookieを含む実応答をそのまま返す。
+    return await fetch(new URL(url.pathname + url.search, backend), {
+      method: request.method,
+      headers,
+      body: ["GET", "HEAD"].includes(request.method)
+        ? undefined
+        : await request.arrayBuffer(),
+      redirect: "manual",
+    });
+  }
+  const relative = normalize(url.pathname.replace(/^\/+/, "") || "index.html");
+  if (relative.startsWith("..")) {
+    return new Response("not found", { status: 404 });
+  }
+  let file = join(build, relative);
+  try {
+    if ((await Deno.stat(file)).isDirectory) file = join(file, "index.html");
+    return new Response(await Deno.readFile(file), {
+      headers: {
+        "content-type": mime[extname(file)] ?? "application/octet-stream",
+      },
+    });
+  } catch (error) {
+    if (!(error instanceof Deno.errors.NotFound)) throw error;
+    if (url.pathname.startsWith("/_app/")) {
+      return new Response("not found", { status: 404 });
+    }
+    return new Response(await Deno.readFile(join(build, "index.html")), {
+      headers: { "content-type": mime[".html"] },
+    });
+  }
+});
+
+// 逐次ceremony/fixtureだけを扱う短いNDJSON bridge。署名/cookieをartifactへ記録しない。
+const input = Deno.stdin.readable.pipeThrough(new TextDecoderStream())
+  .getReader();
+let pending = "";
+async function bridge(operation: string, options: unknown): Promise<unknown> {
+  await Deno.stdout.write(
+    new TextEncoder().encode(JSON.stringify({ operation, options }) + "\n"),
+  );
+  while (!pending.includes("\n")) {
+    const { done, value } = await input.read();
+    if (done) throw new Error("ResidentAuthenticator disconnected");
+    pending += value;
+    if (pending.length > 1024 * 1024) throw new Error("Oversized credential");
+  }
+  const newline = pending.indexOf("\n");
+  const credential = JSON.parse(pending.slice(0, newline));
+  pending = pending.slice(newline + 1);
+  return credential;
+}
+let browser: Browser | undefined;
+let context: BrowserContext | undefined;
+const terminate = () => {
+  void (async () => {
+    await browser?.close();
+    await server.shutdown();
+    Deno.exit(143);
+  })();
+};
+Deno.addSignalListener("SIGTERM", terminate);
+try {
+  browser = await chromium.launch({ headless: true, timeout: 15_000 });
+  context = await browser.newContext();
+  context.setDefaultTimeout(10_000);
+  await context.route(
+    "**/*",
+    (route) =>
+      new URL(route.request().url()).origin === origin
+        ? route.continue()
+        : route.abort(),
+  );
+  await context.exposeBinding(
+    "residentCredential",
+    (_source, operation: string, options: unknown) =>
+      bridge(operation, options),
+  );
+  await context.addInitScript(() => {
+    const encode = (value: unknown): unknown => {
+      if (value instanceof ArrayBuffer) {
+        return btoa(String.fromCharCode(...new Uint8Array(value)))
+          .replaceAll("+", "-").replaceAll("/", "_").replaceAll("=", "");
+      }
+      if (Array.isArray(value)) return value.map(encode);
+      if (value && typeof value === "object") {
+        return Object.fromEntries(
+          Object.entries(value).map(([key, item]) => [key, encode(item)]),
+        );
+      }
+      return value;
+    };
+    const bytes = (value: string) => {
+      const base64 = value.replaceAll("-", "+").replaceAll("_", "/");
+      return Uint8Array.from(
+        atob(base64),
+        (character) => character.charCodeAt(0),
+      ).buffer;
+    };
+    for (const operation of ["create", "get"] as const) {
+      Object.defineProperty(navigator.credentials, operation, {
+        configurable: true,
+        value: async (
+          options: CredentialCreationOptions & CredentialRequestOptions,
+        ) => {
+          const bridge = (window as unknown as {
+            residentCredential: (
+              operation: string,
+              options: unknown,
+            ) => Promise<{
+              id: string;
+              rawId: string;
+              response: Record<string, string | string[] | null>;
+              extensions?: unknown;
+            }>;
+          }).residentCredential;
+          const wire = await bridge(operation, {
+            publicKey: encode(options.publicKey),
+          });
+          const response = Object.fromEntries(
+            Object.entries(wire.response).map((
+              [key, value],
+            ) => [key, typeof value === "string" ? bytes(value) : value]),
+          );
+          return {
+            id: wire.id,
+            rawId: bytes(wire.rawId),
+            type: "public-key",
+            getClientExtensionResults: () => wire.extensions ?? {},
+            response: {
+              ...response,
+              getTransports: () => wire.response.transports ?? [],
+            },
+          };
+        },
+      });
+    }
+  });
+  const page = await context.newPage();
+  const errors: string[] = [];
+  page.on("pageerror", (error) => errors.push(error.message));
+  const at = async (path: string) => {
+    await page.waitForURL((url) =>
+      url.origin === origin && url.pathname + url.search + url.hash === path
+    );
+    console.error(`navigation-ready: ${new URL(path, origin).pathname}`);
+  };
+  const whoami = async () => {
+    const response = await page.request.get(`${origin}/api/auth/whoami`);
+    assertEquals(response.status(), 200);
+    return await response.json();
+  };
+  const account = "/account?view=passkeys&filter=a%2Fb#selected";
+  const privateRequests: string[] = [];
+  const observePrivate = (request: { url(): string }) => {
+    const path = new URL(request.url()).pathname;
+    if (/^\/api\/(workspaces|w\/|hosting\/)/.test(path)) {
+      privateRequests.push(path);
+    }
+  };
+  page.on("request", observePrivate);
+  await page.goto(origin + account);
+  await at("/");
+  await page.getByRole("heading", { name: "Yoi", exact: true }).waitFor();
+  assertEquals((await whoami()).session, { kind: "anonymous" });
+  assertEquals(
+    privateRequests,
+    [],
+    "anonymous gate must run before private loaders",
+  );
+  page.off("request", observePrivate);
+
+  await page.goto(
+    `${origin}/register?${new URLSearchParams({ returnTo: account })}`,
+  );
+  await page.getByLabel("Account ID (handle)", { exact: true }).fill(handle);
+  await page.getByLabel("Display name", { exact: true }).fill(
+    "Real browser E2E",
+  );
+  const registration = page.waitForResponse((response) =>
+    new URL(response.url()).pathname ===
+      "/api/auth/passkeys/registration/complete"
+  );
+  await page.getByRole("button", { name: "Register new account", exact: true })
+    .click();
+  assertEquals((await registration).status(), 200);
+  await at(account);
+  await page.getByRole("button", { name: "Log out", exact: true }).waitFor();
+  const identity = await whoami();
+  assertEquals(identity.actor?.handle, handle);
+  assertEquals(identity.session.kind, "authenticated");
+  assert(typeof identity.session.expires_at === "string");
+  const cookies = await context.cookies(origin);
+  const session = cookies.find((cookie) =>
+    cookie.name === "yoi_workspace_session"
+  );
+  const marker = cookies.find((cookie) =>
+    cookie.name === "yoi_workspace_session_expiry"
+  );
+  assert(session && marker, "Backend must issue both cookies");
+  for (const cookie of [session, marker]) {
+    assert(cookie.httpOnly);
+    assertEquals(cookie.sameSite, "Lax");
+  }
+  const seconds = (Date.parse(identity.session.expires_at) / 1000) -
+    Date.now() / 1000;
+  assert(seconds > 14 * 86400 - 60 && seconds <= 14 * 86400);
+  assert(
+    Math.abs(session.expires - Date.parse(identity.session.expires_at) / 1000) <
+      2,
+  );
+  assert(Math.abs(marker.expires - session.expires - 7 * 86400) < 2);
+  await page.goto(origin + account);
+  await at(account);
+  await page.getByRole("button", { name: "Log out", exact: true }).waitFor();
+  await page.reload();
+  await at(account);
+  await page.getByRole("button", { name: "Log out", exact: true }).waitFor();
+
+  // 明示logoutは実Serverのrevoke + 両cookie削除を通る。
+  await page.getByRole("button", { name: "Log out", exact: true }).click();
+  await at("/");
+  assertEquals((await whoami()).session, { kind: "anonymous" });
+  const afterLogout = await context.cookies(origin);
+  assert(
+    !afterLogout.some((cookie) =>
+      [session.name, marker.name].includes(cookie.name)
+    ),
+  );
+  const revoked = await page.request.get(`${origin}/api/auth/whoami`, {
+    headers: {
+      cookie:
+        `${session.name}=${session.value}; ${marker.name}=${marker.value}`,
+    },
+  });
+  assertEquals((await revoked.json()).session, { kind: "anonymous" });
+  await page.goto(origin + account);
+  await at("/");
+
+  // 実discoverable loginで、確認済みの認証成功後のみpathname/query/fragmentへ復帰する。
+  await page.goto(
+    `${origin}/login?${new URLSearchParams({ returnTo: account })}`,
+  );
+  await page.reload();
+  const login = page.waitForResponse((response) =>
+    new URL(response.url()).pathname === "/api/auth/passkeys/login/complete"
+  );
+  await page.getByRole("button", { name: "Log in with passkey", exact: true })
+    .click();
+  assertEquals((await login).status(), 200);
+  await at(account);
+  await page.getByRole("button", { name: "Log out", exact: true }).waitFor();
+  assertEquals((await whoami()).actor?.handle, handle);
+
+  // 14日実時間の前進ではない。固定expiry実store recordとMax-Age=2のHTTP cookieで、
+  // 自然消失後のmarker→実whoami→製品loader/router→実署名loginの接続を検証する。
+  const expiredTarget = "/dashboard?view=workspaces&filter=a%2Fb&ratio=100%25#selected%25";
+  const catalogResponse = () =>
+    page.waitForResponse((response) =>
+      new URL(response.url()).pathname === "/api/workspaces" &&
+      response.request().method() === "GET"
+    );
+  const initialCatalog = catalogResponse();
+  await page.goto(origin + expiredTarget);
+  assertEquals((await initialCatalog).status(), 200);
+  await at(expiredTarget);
+  await page.getByRole("heading", { name: "Dashboard", exact: true }).waitFor();
+  const issuedStatus = await page.evaluate(async () => {
+    const response = await fetch("/__e2e/expired-session", {
+      method: "POST",
+      cache: "no-store",
+    });
+    return response.status;
+  });
+  assertEquals(issuedStatus, 204);
+  const initiallyPresent = await page.evaluate(async () =>
+    await (await fetch("/__e2e/primary-cookie-present", { cache: "no-store" }))
+      .json()
+  );
+  assertEquals(
+    initiallyPresent,
+    true,
+    "short-lived primary must first reach Chromium",
+  );
+  await page.evaluate(async () => {
+    const deadline = performance.now() + 10_000;
+    do {
+      const response = await fetch("/__e2e/primary-cookie-present", {
+        cache: "no-store",
+      });
+      if (response.ok && await response.json() === false) return;
+      await new Promise((resolve) => setTimeout(resolve, 100));
+    } while (performance.now() < deadline);
+    throw new Error("Primary session cookie did not naturally expire");
+  });
+  // 値をassertionへ渡さず、cookie jarにもprimaryが消えmarkerが残ることを確認する。
+  const expiredCookieNames = (await context.cookies(origin)).map((cookie) =>
+    cookie.name
+  );
+  assert(!expiredCookieNames.includes(session.name));
+  assert(expiredCookieNames.includes(marker.name));
+  assertEquals(await whoami(), {
+    actor: null,
+    session: { kind: "expired" },
+  });
+  privateRequests.length = 0;
+  page.on("request", observePrivate);
+  const expiredWhoami = page.waitForResponse((response) =>
+    new URL(response.url()).pathname === "/api/auth/whoami"
+  );
+  await page.reload();
+  const expiredResponse = await expiredWhoami;
+  assertEquals(expiredResponse.status(), 200);
+  // SPAがloginへ移った後の旧document bodyをCDPから読み直さない。
+  // 分類本文は直前/復帰待ち後にも同じ実Backendから取得し、browser要求はstatusを観測する。
+  const expiredLogin = `/login?${new URLSearchParams({
+    returnTo: expiredTarget,
+  })}`;
+  await at(expiredLogin);
+  await page.getByRole("button", { name: "Log in with passkey", exact: true })
+    .waitFor();
+  assertEquals(
+    privateRequests,
+    [],
+    "expired reload must gate the real private catalog loader",
+  );
+  assertEquals(await whoami(), { actor: null, session: { kind: "expired" } });
+  await page.reload();
+  await at(expiredLogin);
+  await page.getByRole("button", { name: "Log in with passkey", exact: true })
+    .waitFor();
+  assertEquals(
+    privateRequests,
+    [],
+    "login reload must not lose or privately load returnTo",
+  );
+  page.off("request", observePrivate);
+  const recoveredCatalog = catalogResponse();
+  const relogin = page.waitForResponse((response) =>
+    new URL(response.url()).pathname === "/api/auth/passkeys/login/complete"
+  );
+  await page.getByRole("button", { name: "Log in with passkey", exact: true })
+    .click();
+  assertEquals((await relogin).status(), 200);
+  await at(expiredTarget);
+  assertEquals((await recoveredCatalog).status(), 200);
+  await page.getByRole("heading", { name: "Dashboard", exact: true }).waitFor();
+  const recovered = await whoami();
+  assertEquals(recovered.session.kind, "authenticated");
+  assertEquals(recovered.actor?.user_id, identity.actor.user_id);
+  assertEquals(recovered.actor?.handle, handle);
+  await page.goto(origin + account);
+  await at(account);
+  await page.getByRole("button", { name: "Log out", exact: true }).waitFor();
+
+  // fixtureでprimaryだけを除去。Server時計は進めていないため、markerのみでは
+  // authenticatedにもexpiredにもならない。これを14日経過の成功とは数えない。
+  await context.clearCookies({ name: session.name });
+  const partial = await whoami();
+  assertEquals(partial, { actor: null, session: { kind: "anonymous" } });
+  await page.reload();
+  await at("/");
+  await context.clearCookies();
+  await page.goto(origin + account);
+  await at("/");
+  assertEquals((await whoami()).session, { kind: "anonymous" });
+  assertEquals(errors, []);
+} finally {
+  await context?.close();
+  await browser?.close();
+  await server.shutdown();
+  Deno.removeSignalListener("SIGTERM", terminate);
+}
+await Deno.stdout.write(new TextEncoder().encode('{"operation":"done"}\n'));
+// 親はstdout EOFで完了を確定する。stdin streamのprefetch取消を待つと相互待ちになる。
+Deno.exit(0);
diff --git a/tests/e2e/tests/auth_passkeys.rs b/tests/e2e/tests/auth_passkeys.rs
index 95dce869b..7195bb3bb 100644
--- a/tests/e2e/tests/auth_passkeys.rs
+++ b/tests/e2e/tests/auth_passkeys.rs
@@ -1,11 +1,12 @@
 //! 隔離した実yoi-serverのhost CLI・HTTP APIで、管理者初期設定、登録可否の永続化、
 //! ID不要login、本人の鍵追加、限定activation、Workspace所有・catalog選択境界を検証する。DB・認証・routerは本番実装を使い、
-//! authenticatorはresident store/選択を持つsoftware model、署名エンジンのみSoftPasskeyとする（browser UI／OS認証器は対象外）。
+//! authenticatorはresident store/選択を持つsoftware model、署名エンジンのみSoftPasskeyとする（OS／物理認証器は対象外）。
 //! `cargo test -p yoi-e2e --features e2e --test auth_passkeys`で明示選択する。
 //! binary供給、HOME/XDG/DB/動的port、readiness、ログ、RAII回収は共有harnessが所有する。
-//! HTTPはproxy／redirect／cookie storeなし、各要求にtimeoutを設ける。
-//! `/`・`/login`・`/dashboard`のstatic shellは対象外。実Server CLIにはstatic assets設定経路がなく、
-//! shell表示／browser遷移は本番routerのin-process検証やbrowser側の合成HTTP検証と区別する。
+//! 通常ケースのHTTPはproxy／redirect／cookie storeなし、各要求にtimeoutを設ける。
+//! 実Server CLIにはstatic assets設定経路がない。追加の明示選択browser_sessionsだけが
+//! 本番static shellをloopback proxyで実Backendへ接続し、Cookieの自然消失と復帰を検証する。
+//! 固定expiry sessionを公開store APIで作るfixture境界と、14日実時間経過の未検証は同moduleに記す。
 
 use std::error::Error;
 use std::fs::OpenOptions;
@@ -29,6 +30,9 @@ mod resident_model;
 use resident_model::ResidentAuthenticator;
 use yoi_e2e::WorkerE2eEnvironment;
 
+#[path = "auth_passkeys/browser_sessions.rs"]
+mod browser_sessions;
+
 type Result<T = ()> = std::result::Result<T, Box<dyn Error>>;
 const BROWSER_ORIGIN: &str = "http://localhost:5173";
 
diff --git a/tests/e2e/tests/auth_passkeys/browser_sessions.rs b/tests/e2e/tests/auth_passkeys/browser_sessions.rs
new file mode 100644
index 000000000..7207e4124
--- /dev/null
+++ b/tests/e2e/tests/auth_passkeys/browser_sessions.rs
@@ -0,0 +1,233 @@
+//! 実Backend・本番static shell・Chromium cookie jarの接続を検証する。
+//! navigator.credentialsだけを共有ResidentAuthenticatorの署名へ接続する。
+//! 期限切れケースは実登録userへ公開store APIで固定expiry sessionを作り、
+//! 本番cookie生成関数の短命primary/猶予markerをfixture HTTPで配信する。
+//! SQL直書き・resolver/APIの置換・製品clockの追加はしない。
+//! 実発行14日cookieの属性/DTOと短命fixtureの自然消失/復帰を分けて検証する。
+//! OS/物理認証器と14日経過したServer時計は検証しない。
+//! Deno/Playwright Chromiumと最新production buildが必要な明示選択suite:
+//! `cargo test -p yoi-e2e --features e2e --test auth_passkeys real_backend_browser -- --ignored`
+//! 通常auth_passkeysの成功/ignoreを、このbrowser接続の実行成功とは数えない。
+use super::*;
+use std::io::{BufRead, BufReader, Read};
+use std::net::TcpListener;
+use std::process::{Child, Command, Stdio};
+use std::sync::mpsc;
+use std::time::Instant;
+use yoi_workspace_server::auth::{
+    SESSION_EXPIRY_GRACE_SECONDS, SessionCookiePolicy, mint_secret, new_id,
+    session_marker_cookie_name, session_set_cookie, token_hash,
+};
+use yoi_workspace_server::store::{BrowserSessionRecord, ControlPlaneStore, SqliteWorkspaceStore};
+
+// 戻り値はprivate IPC→fixture HTTPのSet-Cookieだけに使い、assert/debug/artifactへ出さない。
+fn expired_session_fixture(environment: &WorkerE2eEnvironment) -> Result<Value> {
+    // default環境や任意pathへ接続せず、このenvironmentが起動した既存DBだけを開く。
+    let database = environment
+        .server_data_dir
+        .join("server.db")
+        .canonicalize()?;
+    if !database.starts_with(environment.root.canonicalize()?) {
+        return Err("expired-session fixture DB is outside its environment".into());
+    }
+    let store = SqliteWorkspaceStore::open(database)?;
+    let user = store
+        .get_user_by_handle(&environment.account_handle)?
+        .ok_or("browser registration must create the fixture user first")?;
+    let token = mint_secret("yoi_sess");
+    let hash = token_hash(&token);
+    let now = chrono::Utc::now();
+    // Server時計を動かさず、既に期限切れだが実猶予内のrecordを公開store APIで保存する。
+    store.create_browser_session(&BrowserSessionRecord {
+        session_id: new_id("session"),
+        token_hash: hash.clone(),
+        user_id: user.user_id,
+        created_at: (now - chrono::Duration::days(14) - chrono::Duration::seconds(60)).to_rfc3339(),
+        expires_at: (now - chrono::Duration::seconds(60)).to_rfc3339(),
+        revoked_at: None,
+    })?;
+    let policy = SessionCookiePolicy {
+        cookie_name: "yoi_workspace_session",
+        path: "/",
+        domain: None,
+        secure: false,
+    };
+    let marker_name = session_marker_cookie_name(policy.cookie_name);
+    Ok(json!({"set_cookies": [
+        session_set_cookie(policy, &token, 2),
+        session_set_cookie(SessionCookiePolicy {
+            cookie_name: &marker_name,
+            ..policy
+        }, &hash, SESSION_EXPIRY_GRACE_SECONDS - 60),
+    ]}))
+}
+
+struct BrowserProcess(Option<Child>);
+impl BrowserProcess {
+    fn child(&mut self) -> &mut Child {
+        self.0.as_mut().expect("browser process retained")
+    }
+}
+impl Drop for BrowserProcess {
+    fn drop(&mut self) {
+        let Some(mut child) = self.0.take() else {
+            return;
+        };
+        if matches!(child.try_wait(), Ok(Some(_))) {
+            return;
+        }
+        let pid = child.id() as libc::pid_t;
+        // Denoのsignal handlerがPlaywright/HTTPを閉じる猶予を与える。
+        unsafe {
+            libc::kill(pid, libc::SIGTERM);
+        }
+        let (send, receive) = mpsc::channel();
+        let waiter = std::thread::spawn(move || {
+            let _ = send.send(child.wait());
+        });
+        if receive.recv_timeout(Duration::from_secs(3)).is_err() {
+            unsafe {
+                libc::kill(pid, libc::SIGKILL);
+            }
+        }
+        let _ = waiter.join();
+    }
+}
+
+#[test]
+#[ignore = "requires production Web assets, Deno and Playwright Chromium"]
+fn real_backend_browser_cookies_preserve_identity_expiry_return_url_and_explicit_logout() -> Result
+{
+    // Backend/process/DBの所有は既存harnessに限定する。Web buildは呼出元が用意する。
+    let root = Path::new(env!("CARGO_MANIFEST_DIR")).join("../..");
+    let build = root.join("web/workspace/build");
+    if !build.join("index.html").is_file() {
+        return Err("build web/workspace production assets before selecting browser E2E".into());
+    }
+    let mut environment = WorkerE2eEnvironment::new()?;
+    let reservation = TcpListener::bind("127.0.0.1:0")?;
+    let port = reservation.local_addr()?.port();
+    let origin = format!("http://localhost:{port}");
+    std::fs::write(
+        &environment.server_config,
+        format!("[browser]\npublic_url = \"{origin}\"\n"),
+    )?;
+    environment.start_empty_backend()?;
+    let admin =
+        environment.setup_hosting_admin(&format!("{}-admin", environment.account_handle), true)?;
+    let bearer = admin["access_token"]
+        .as_str()
+        .ok_or("missing setup token")?;
+    let base = environment
+        .server_url
+        .as_deref()
+        .ok_or("missing Backend URL")?;
+    success(
+        http_client()?
+            .put(format!("{base}/api/hosting/settings"))
+            .bearer_auth(bearer)
+            .json(&json!({"self_registration_enabled": true}))
+            .send()?,
+    )?;
+    drop(reservation);
+    let stderr = std::fs::File::create(environment.artifacts_dir.join("browser.stderr.log"))?;
+    let mut process = BrowserProcess(Some(
+        Command::new("deno")
+            .current_dir(&root)
+            .args([
+                "run",
+                "--config",
+                "tools/web-ux/deno.json",
+                "--no-lock",
+                "--allow-env",
+                "--allow-net",
+                "--allow-read",
+                "--allow-write",
+                "--allow-run",
+                "--allow-sys",
+                "tests/e2e/browser/auth_sessions.ts",
+                base,
+                &origin,
+                build.to_str().ok_or("non-UTF8 build path")?,
+                &environment.account_handle,
+            ])
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .stderr(stderr)
+            .spawn()?,
+    ));
+    let stdout = process
+        .child()
+        .stdout
+        .take()
+        .ok_or("missing browser stdout")?;
+    let mut stdin = process
+        .child()
+        .stdin
+        .take()
+        .ok_or("missing browser stdin")?;
+    let (send, receive) = mpsc::sync_channel(4);
+    // bounded NDJSONは実WebAuthn options/署名とfixture cookieを運び、artifactには記録しない。
+    let reader = std::thread::spawn(move || {
+        let mut reader = BufReader::new(stdout);
+        loop {
+            let mut line = String::new();
+            match reader.by_ref().take(1024 * 1024).read_line(&mut line) {
+                Ok(0) => break,
+                Ok(_) if line.ends_with('\n') => {
+                    if send.send(Ok(line)).is_err() {
+                        break;
+                    }
+                }
+                _ => {
+                    let _ = send.send(Err("invalid or oversized browser IPC"));
+                    break;
+                }
+            }
+        }
+    });
+    let deadline = Instant::now() + Duration::from_secs(120);
+    let mut authenticator = ResidentAuthenticator::new(true);
+    let mut completed = false;
+    loop {
+        let message = match receive.recv_timeout(deadline.saturating_duration_since(Instant::now()))
+        {
+            Ok(message) => message.map_err(std::io::Error::other)?,
+            Err(mpsc::RecvTimeoutError::Disconnected) => break,
+            Err(_) => return Err("browser E2E timed out; see browser.stderr.log".into()),
+        };
+        let request: Value = serde_json::from_str(&message)?;
+        let credential = match request["operation"].as_str() {
+            Some("create") => serde_json::to_value(authenticator.do_registration(
+                origin.parse()?,
+                serde_json::from_value(request["options"].clone())?,
+            )?)?,
+            Some("get") => serde_json::to_value(authenticator.do_authentication(
+                origin.parse()?,
+                serde_json::from_value(request["options"].clone())?,
+            )?)?,
+            Some("expired-session") => expired_session_fixture(&environment)?,
+            Some("done") => {
+                completed = true;
+                continue;
+            }
+            _ => return Err("unexpected browser IPC operation".into()),
+        };
+        serde_json::to_writer(&mut stdin, &credential)?;
+        writeln!(stdin)?;
+        stdin.flush()?;
+    }
+    reader.join().map_err(|_| "browser reader panicked")?;
+    assert!(
+        completed,
+        "browser did not complete; see browser.stderr.log"
+    );
+    assert!(
+        process.child().wait()?.success(),
+        "browser E2E failed; see browser.stderr.log"
+    );
+    drop(process);
+    let report = environment.cleanup()?;
+    assert!(report.cleanup_success);
+    Ok(())
+}
diff --git a/web/workspace/src/lib/generated/auth-api.ts b/web/workspace/src/lib/generated/auth-api.ts
index 774a2852b..788ded8eb 100644
--- a/web/workspace/src/lib/generated/auth-api.ts
+++ b/web/workspace/src/lib/generated/auth-api.ts
@@ -19,7 +19,9 @@ export type AuthenticatedUser = { user_id: string, account_id: string, handle: s
 
 export type RequestActor = { user_id: string, account_id: string, handle: string, display_name: string, auth_method: ActorAuthMethod, };
 
-export type WhoamiResponse = { actor: RequestActor | null, };
+export type BrowserSessionState = { "kind": "anonymous", } | { "kind": "authenticated", expires_at: string | null, } | { "kind": "expired", };
+
+export type WhoamiResponse = { actor: RequestActor | null, session: BrowserSessionState, };
 
 export type AuthBootstrapUserRequest = { handle: string, display_name?: string | null, };
 
diff --git a/web/workspace/src/lib/generated/companion-api.ts b/web/workspace/src/lib/generated/companion-api.ts
index 146d0ce28..5c09ef0af 100644
--- a/web/workspace/src/lib/generated/companion-api.ts
+++ b/web/workspace/src/lib/generated/companion-api.ts
@@ -1,6 +1,6 @@
 // @generated by yoi-companion-openapi-typescript@1. Do not edit.
 // Input: openapi/server-api.json
-// Input contract: 0.1.0 (sha256:4e01d7dd0dab015ba3204045da33d7b87c9edc166b7dad464a8ab0d61e0f0e6d)
+// Input contract: 0.1.0 (sha256:3cd508b4b2c8e82c8f185092bada8e8ec3e1d8f8f503a12775f6014765e5b45f)
 // Options: companion-operation-schema-closure,openapi-3.1,strict-integer-ranges,sorted-output
 // Output: web/workspace/src/lib/generated/companion-api.ts
 // Regenerate/check: cargo run -q -p server-api --example generate_companion_api_types -- --check
diff --git a/web/workspace/src/lib/generated/repository-api.ts b/web/workspace/src/lib/generated/repository-api.ts
index 74a8c9547..6fcb5b03d 100644
--- a/web/workspace/src/lib/generated/repository-api.ts
+++ b/web/workspace/src/lib/generated/repository-api.ts
@@ -1,6 +1,6 @@
 // @generated by yoi-repository-openapi-typescript@1. Do not edit.
 // Input: openapi/server-api.json
-// Input contract: 0.1.0 (sha256:4e01d7dd0dab015ba3204045da33d7b87c9edc166b7dad464a8ab0d61e0f0e6d)
+// Input contract: 0.1.0 (sha256:3cd508b4b2c8e82c8f185092bada8e8ec3e1d8f8f503a12775f6014765e5b45f)
 // Options: repository-operation-schema-closure,openapi-3.1,format:uint64=safe-number,strict-safe-integers,sorted-output
 // Output: web/workspace/src/lib/generated/repository-api.ts
 // Regenerate/check: cargo run -q -p server-api --example generate_repository_openapi_types -- --check
diff --git a/web/workspace/src/lib/generated/runtime-api.ts b/web/workspace/src/lib/generated/runtime-api.ts
index 138ed0fd1..79c053a6d 100644
--- a/web/workspace/src/lib/generated/runtime-api.ts
+++ b/web/workspace/src/lib/generated/runtime-api.ts
@@ -1,6 +1,6 @@
 // @generated by yoi-runtime-openapi-typescript@1. Do not edit.
 // Input: openapi/server-api.json
-// Input contract: 0.1.0 (sha256:4e01d7dd0dab015ba3204045da33d7b87c9edc166b7dad464a8ab0d61e0f0e6d)
+// Input contract: 0.1.0 (sha256:3cd508b4b2c8e82c8f185092bada8e8ec3e1d8f8f503a12775f6014765e5b45f)
 // Options: runtime-operation-schema-closure,openapi-3.1,strict-integer-ranges,sorted-output
 // Output: web/workspace/src/lib/generated/runtime-api.ts
 // Regenerate/check: cargo run -q -p server-api --example generate_runtime_api_types -- --check
diff --git a/web/workspace/src/lib/generated/ticket-api.ts b/web/workspace/src/lib/generated/ticket-api.ts
index 2dbcf6109..11391dbd3 100644
--- a/web/workspace/src/lib/generated/ticket-api.ts
+++ b/web/workspace/src/lib/generated/ticket-api.ts
@@ -1,6 +1,6 @@
 // @generated by yoi-ticket-browser-openapi-typescript@1. Do not edit.
 // Input: openapi/server-api.json
-// Input contract: 0.1.0 (sha256:4e01d7dd0dab015ba3204045da33d7b87c9edc166b7dad464a8ab0d61e0f0e6d)
+// Input contract: 0.1.0 (sha256:3cd508b4b2c8e82c8f185092bada8e8ec3e1d8f8f503a12775f6014765e5b45f)
 // Options: ticket-objective-merge-request-browser-operation-schema-closure,openapi-3.1,strict-integer-ranges,sorted-output
 // Output: web/workspace/src/lib/generated/ticket-api.ts
 // Regenerate/check: cargo run -q -p server-api --example generate_ticket_api_types -- --check
diff --git a/web/workspace/src/lib/generated/worker-launch-api.ts b/web/workspace/src/lib/generated/worker-launch-api.ts
index 8fff5d2ea..63f2881c3 100644
--- a/web/workspace/src/lib/generated/worker-launch-api.ts
+++ b/web/workspace/src/lib/generated/worker-launch-api.ts
@@ -1,6 +1,6 @@
 // @generated by yoi-worker-openapi-typescript@1. Do not edit.
 // Input: openapi/server-api.json
-// Input contract: 0.1.0 (sha256:4e01d7dd0dab015ba3204045da33d7b87c9edc166b7dad464a8ab0d61e0f0e6d)
+// Input contract: 0.1.0 (sha256:3cd508b4b2c8e82c8f185092bada8e8ec3e1d8f8f503a12775f6014765e5b45f)
 // Options: worker-operation-schema-closure,openapi-3.1,strict-integer-ranges,sorted-output
 // Output: web/workspace/src/lib/generated/worker-launch-api.ts
 // Regenerate/check: cargo run -q -p server-api --example generate_worker_launch_api_types -- --check
diff --git a/web/workspace/src/lib/workspace/api/http.ts b/web/workspace/src/lib/workspace/api/http.ts
index 27773b1bc..02dc0f39e 100644
--- a/web/workspace/src/lib/workspace/api/http.ts
+++ b/web/workspace/src/lib/workspace/api/http.ts
@@ -1,3 +1,7 @@
+import {
+  browserSession,
+  recheckAfterUnauthorized,
+} from "#lib/workspace/auth/session-state.ts";
 import { SKILL_API_LIMITS } from "#lib/generated/skill-api.ts";
 import type {
   SkillCatalogResponse,
@@ -102,7 +106,11 @@ export async function loadJson<T>(
 ): Promise<ApiResult<T>> {
   let stage: "request" | "decode" | "validate" = "request";
   try {
+    const authenticationGeneration = browserSession.authenticationGeneration;
     const response = await fetchFn(path, init);
+    if (response.status === 401) {
+      recheckAfterUnauthorized(authenticationGeneration);
+    }
     if (!response.ok) {
       if (policy) {
         await response.body?.cancel();
diff --git a/web/workspace/src/lib/workspace/auth/AuthEntry.svelte b/web/workspace/src/lib/workspace/auth/AuthEntry.svelte
index 2dafcddd9..46e41c345 100644
--- a/web/workspace/src/lib/workspace/auth/AuthEntry.svelte
+++ b/web/workspace/src/lib/workspace/auth/AuthEntry.svelte
@@ -2,7 +2,8 @@
   import { onMount } from 'svelte';
   import { goto } from '$app/navigation';
   import { page } from '$app/state';
-  import { loginWithLegacyPasskey, loginWithPasskey, registerPasskey } from './api.ts';
+  import { loginWithLegacyPasskey, loginWithPasskey, registerPasskey, logout } from './api.ts';
+  import { CLEAR_RETURN_EVENT } from './session-state.ts';
   import { BrowserAuth } from './browser-session.svelte.ts';
   import { loadRegistrationPolicy } from './hosting.ts';
   import { authEntryUrl, safeReturnTo, AUTHENTICATED_HOME } from './routes.ts';
@@ -58,11 +59,16 @@
     }
   }
 
+  async function forget() {
+    await auth.run('Logging out…', 'Logged out.', logout, 'logout');
+  }
   onMount(() => {
+    const clearReturn = () => { void goto(page.url.pathname, { replaceState: true }); };
+    window.addEventListener(CLEAR_RETURN_EVENT, clearReturn);
     void auth.refresh();
     void refreshPolicy();
     window.addEventListener('focus', refreshPolicy);
-    return () => { ++policyRequest; auth.dispose(); window.removeEventListener('focus', refreshPolicy); };
+    return () => { ++policyRequest; auth.dispose(); window.removeEventListener('focus', refreshPolicy); window.removeEventListener(CLEAR_RETURN_EVENT, clearReturn); };
   });
 </script>
 
@@ -74,11 +80,16 @@
   {:else if auth.session.kind === 'error'}
     <p role="alert" class="error">Your session could not be loaded. Login status is unknown.</p>
     <button type="button" disabled={auth.busy} onclick={() => auth.refresh()}>Retry session</button>
+    <button type="button" disabled={auth.busy} onclick={forget}>Forget this session</button>
   {:else if auth.actor}
     <p>Logged in as <strong>{auth.actor.display_name}</strong> <span class="muted">@{auth.actor.handle}</span>.</p>
     <a href={destination}>Continue to {destination === AUTHENTICATED_HOME ? 'dashboard / Workspaces' : 'requested page'}</a>
     <a href="/account">Open Account</a>
   {:else}
+    {#if auth.session.session.kind === 'expired'}
+      <p role="status">Your browser session expired. Log in to return to the requested page.</p>
+      <button type="button" disabled={auth.busy} onclick={forget}>Forget this session</button>
+    {/if}
     {#if mode === 'register'}
       {#if policyLoading}
         <p role="status" class="muted">Checking registration availability…</p>
diff --git a/web/workspace/src/lib/workspace/auth/SessionBoundary.svelte b/web/workspace/src/lib/workspace/auth/SessionBoundary.svelte
new file mode 100644
index 000000000..e910913e6
--- /dev/null
+++ b/web/workspace/src/lib/workspace/auth/SessionBoundary.svelte
@@ -0,0 +1,71 @@
+<script lang="ts">
+  import { onMount, type Snippet } from 'svelte';
+  import { goto, invalidate } from '$app/navigation';
+  import { page } from '$app/state';
+  import { browserSession, observeBrowserSession, type SessionSnapshot } from './session-state.ts';
+  import { isPublicPage, loginUrl } from './routes.ts';
+  import './auth-page.css';
+
+  let { children }: { children: Snippet } = $props();
+  let session = $state<SessionSnapshot>(browserSession.snapshot);
+  let admitted = $state(browserSession.snapshot.kind === 'ready' && browserSession.snapshot.value.session.kind === 'authenticated');
+  const actorKey = $derived(session.kind === 'ready' && session.value.actor
+    ? `${session.value.actor.user_id}:${session.value.actor.account_id}` : null);
+  let admittedActor = $state<string | null>(browserSession.snapshot.kind === 'ready' && browserSession.snapshot.value.actor
+    ? `${browserSession.snapshot.value.actor.user_id}:${browserSession.snapshot.value.actor.account_id}` : null);
+  const sameActor = $derived(admittedActor === null || admittedActor === actorKey);
+  const protectedPage = $derived(!isPublicPage(page.url.pathname));
+  let navigating = false;
+
+  onMount(() => {
+    observeBrowserSession();
+    return browserSession.subscribe((snapshot) => {
+      // 子onMountの再確認より前に入場を記録する。effect後回しだとloadingの度に
+      // childを再mountし、onMount→whoami→unmountの反復を作ってしまう。
+      if (snapshot.kind === 'ready' && snapshot.value.session.kind === 'authenticated') admitted = true;
+      session = snapshot;
+    });
+  });
+  $effect(() => {
+    if (!protectedPage || session.kind !== 'ready') return;
+    const state = session.value.session.kind;
+    if (state === 'authenticated') {
+      if (!sameActor) {
+        // 別tabで主体が変わった場合、旧主体で取得したloader/subscriptionを再利用しない。
+        if (!navigating) { navigating = true; location.reload(); }
+        return;
+      }
+      admittedActor = actorKey;
+      admitted = true;
+      return;
+    }
+    admitted = false;
+    if (navigating) return;
+    navigating = true;
+    const target = state === 'expired'
+      ? loginUrl(location.pathname + location.search + location.hash) : '/';
+    void goto(target, { replaceState: true }).finally(() => { navigating = false; });
+  });
+  async function retry() {
+    await browserSession.refresh();
+    await invalidate('auth:session');
+  }
+</script>
+
+{#if !protectedPage}
+  {@render children()}
+{:else}
+  {#if session.kind === 'loading'}
+    <div class="auth-page"><p role="status">Loading session…</p></div>
+  {:else if session.kind === 'error'}
+    <div class="auth-page">
+      <p class="error" role="alert">Your session could not be loaded. Login status is unknown.</p>
+      <button type="button" onclick={retry}>Retry session</button>
+      <a href="/">Yoi home</a>
+    </div>
+  {/if}
+  {#if session.kind === 'ready' ? session.value.session.kind === 'authenticated' && sameActor : admitted}
+    <!-- 再確認中は表示/操作を停止し、進行中のlogout等をunmountで取消さない。 -->
+    <div hidden={session.kind !== 'ready'} inert={session.kind !== 'ready'}>{@render children()}</div>
+  {/if}
+{/if}
diff --git a/web/workspace/src/lib/workspace/auth/api.test-fixtures.ts b/web/workspace/src/lib/workspace/auth/api.test-fixtures.ts
index ad24e6937..3cbac0ddf 100644
--- a/web/workspace/src/lib/workspace/auth/api.test-fixtures.ts
+++ b/web/workspace/src/lib/workspace/auth/api.test-fixtures.ts
@@ -63,3 +63,12 @@ export function credentialFixture(authentication = false): Credential {
       },
   } as unknown as Credential;
 }
+
+export function whoamiPayload(actor: unknown = null) {
+  return {
+    actor,
+    session: actor === null
+      ? { kind: "anonymous" }
+      : { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+  };
+}
diff --git a/web/workspace/src/lib/workspace/auth/browser-session.svelte.ts b/web/workspace/src/lib/workspace/auth/browser-session.svelte.ts
index f956e48fa..d69840eb2 100644
--- a/web/workspace/src/lib/workspace/auth/browser-session.svelte.ts
+++ b/web/workspace/src/lib/workspace/auth/browser-session.svelte.ts
@@ -1,16 +1,21 @@
-import { AuthRequestError, loadWhoami } from "./api.ts";
+import { AuthRequestError } from "./api.ts";
+import {
+  browserSession,
+  observeBrowserSession,
+  sessionMutation,
+} from "./session-state.ts";
 import { notifySessionChanged } from "./hosting.ts";
-import type { RequestActor } from "./model.ts";
+import type { RequestActor, WhoamiResponse } from "./model.ts";
 
 export type BrowserSession =
   | { kind: "loading" }
   | { kind: "error" }
-  | { kind: "ready"; actor: RequestActor | null };
+  | ({ kind: "ready" } & WhoamiResponse);
 
 export function authErrorMessage(error: unknown): string {
   if (error instanceof AuthRequestError) {
     if (error.status === 401) {
-      return "Your session or authentication challenge expired. Log in again or restart the Passkey operation.";
+      return "Authentication request was rejected. Check your session or restart the Passkey operation.";
     }
     if (error.status === 400 || error.status === 410) {
       return "The request or authentication challenge is invalid or expired. Restart the operation.";
@@ -35,61 +40,77 @@ export class BrowserAuth {
   busy = $state(false);
   error = $state("");
   status = $state("");
-  private request = 0;
+  private unsubscribe: () => void;
   private disposed = false;
   private controller: AbortController | null = null;
 
+  constructor() {
+    observeBrowserSession();
+    this.unsubscribe = browserSession.subscribe((snapshot) => {
+      // 操作pendingはsession確認中と別。formを消してfocus/入力を失わず、busyで再操作を止める。
+      if (this.busy && snapshot.kind === "loading") return;
+      if (!this.disposed) {
+        this.session = snapshot.kind === "ready"
+          ? { kind: "ready", ...snapshot.value }
+          : snapshot;
+      }
+    });
+  }
+
   get actor(): RequestActor | null {
     return this.session.kind === "ready" ? this.session.actor : null;
   }
 
   async refresh(): Promise<void> {
     if (this.busy || this.disposed) return;
-    await this.readSession();
-  }
-
-  private async readSession(): Promise<void> {
-    const current = ++this.request;
-    this.session = { kind: "loading" };
-    try {
-      const result = await loadWhoami();
-      if (this.disposed || current !== this.request) return;
-      this.session = { kind: "ready", actor: result.actor };
-    } catch {
-      if (this.disposed || current !== this.request) return;
-      this.session = { kind: "error" };
-    }
+    await browserSession.refresh();
   }
 
   async run(
     pending: string,
     success: string,
     operation: (signal: AbortSignal) => Promise<unknown>,
+    intent: "authentication" | "logout" = "authentication",
   ): Promise<boolean> {
-    if (this.busy || this.disposed || this.session.kind !== "ready") {
+    if (
+      this.busy || this.disposed ||
+      (intent !== "logout" && this.session.kind !== "ready")
+    ) {
       return false;
     }
     this.busy = true;
-    ++this.request;
+    sessionMutation(intent);
+    const authenticationGeneration = browserSession.authenticationGeneration;
     const controller = new AbortController();
     this.controller = controller;
     this.error = "";
     this.status = pending;
     try {
       await operation(controller.signal);
-      if (this.disposed) return false;
+      const superseded =
+        authenticationGeneration !== browserSession.authenticationGeneration;
+      sessionMutation(intent);
+      const confirmationGeneration = browserSession.authenticationGeneration;
+      await browserSession.refresh();
+      if (
+        this.disposed || superseded ||
+        confirmationGeneration !== browserSession.authenticationGeneration
+      ) {
+        if (!this.disposed) this.status = "";
+        return false;
+      }
       notifySessionChanged();
-      await this.readSession();
-      if (this.disposed) return false;
       const confirmed = this.session.kind === "ready";
       this.status = confirmed ? success : "";
       return confirmed;
     } catch (error) {
-      if (this.disposed) return false;
-      this.error = authErrorMessage(error);
-      this.status = "";
+      if (!this.disposed) {
+        this.error = authErrorMessage(error);
+        this.status = "";
+      }
       // 失効/応答不明でも既存actorを操作権限として保持せず、正本を読み直す。
-      await this.readSession();
+      sessionMutation(intent);
+      await browserSession.refresh();
       return false;
     } finally {
       if (!this.disposed) {
@@ -101,7 +122,7 @@ export class BrowserAuth {
 
   dispose(): void {
     this.disposed = true;
-    ++this.request;
+    this.unsubscribe();
     this.controller?.abort();
   }
 }
diff --git a/web/workspace/src/lib/workspace/auth/model.test.ts b/web/workspace/src/lib/workspace/auth/model.test.ts
index 177db4b8f..4c17c2df3 100644
--- a/web/workspace/src/lib/workspace/auth/model.test.ts
+++ b/web/workspace/src/lib/workspace/auth/model.test.ts
@@ -118,10 +118,14 @@ Deno.test("prepareLoginOptions decodes challenge and allowed credential ids", ()
 });
 
 Deno.test("whoami rejects unknown auth methods and extra fields", () => {
-  assertEquals(parseWhoamiResponse({ actor: null }), { actor: null });
+  assertEquals(
+    parseWhoamiResponse({ actor: null, session: { kind: "anonymous" } }),
+    { actor: null, session: { kind: "anonymous" } },
+  );
   assertThrows(
     () =>
       parseWhoamiResponse({
+        session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
         actor: {
           user_id: "user-1",
           account_id: "account-1",
@@ -233,3 +237,34 @@ Deno.test("passkey credential conversion fails closed on malformed payloads", ()
     "unknown credential type",
   );
 });
+
+Deno.test("whoami fails closed on actor-state mismatch and malformed expiry", () => {
+  const actor = {
+    user_id: "u",
+    account_id: "a",
+    handle: "alice",
+    display_name: "Alice",
+    auth_method: "browser_session",
+  };
+  for (
+    const payload of [
+      { actor, session: { kind: "anonymous" } },
+      { actor, session: { kind: "expired" } },
+      {
+        actor: null,
+        session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+      },
+      { actor, session: { kind: "authenticated", expires_at: null } },
+      { actor, session: { kind: "authenticated", expires_at: "tomorrow" } },
+      { actor: null, session: { kind: "future" } },
+      {
+        actor: null,
+        session: { kind: "expired", expires_at: "2099-01-01T00:00:00Z" },
+      },
+    ]
+  ) assertThrows(() => parseWhoamiResponse(payload), "inconsistent whoami");
+  assertEquals(
+    parseWhoamiResponse({ actor: null, session: { kind: "expired" } }),
+    { actor: null, session: { kind: "expired" } },
+  );
+});
diff --git a/web/workspace/src/lib/workspace/auth/model.ts b/web/workspace/src/lib/workspace/auth/model.ts
index a52b2e5a4..5923f32b8 100644
--- a/web/workspace/src/lib/workspace/auth/model.ts
+++ b/web/workspace/src/lib/workspace/auth/model.ts
@@ -463,12 +463,40 @@ function parseActor(value: unknown, path: string): RequestActor {
 
 export function parseWhoamiResponse(value: unknown): WhoamiResponse {
   const response = asRecord(value, "whoami");
-  requireExactKeys(response, "whoami", ["actor"]);
-  return {
-    actor: response.actor === null
+  requireExactKeys(response, "whoami", ["actor", "session"]);
+  const actor = response.actor === null
+    ? null
+    : parseActor(response.actor, "whoami.actor");
+  const session = asRecord(response.session, "whoami.session");
+  if (session.kind === "authenticated") {
+    requireExactKeys(session, "whoami.session", ["kind", "expires_at"]);
+    if (actor === null) {
+      invalid("whoami", "authenticated session requires actor");
+    }
+    const expiry = session.expires_at === null
       ? null
-      : parseActor(response.actor, "whoami.actor"),
-  };
+      : boundedString(session.expires_at, "whoami.session.expires_at");
+    if (
+      (expiry !== null &&
+        (!/^\d{4}-\d\d-\d\dT/.test(expiry) ||
+          !Number.isFinite(Date.parse(expiry)))) ||
+      (actor.auth_method === "browser_session" && expiry === null)
+    ) {
+      invalid(
+        "whoami.session.expires_at",
+        "must identify the server session expiry",
+      );
+    }
+    return { actor, session: { kind: "authenticated", expires_at: expiry } };
+  }
+  requireExactKeys(session, "whoami.session", ["kind"]);
+  if (
+    actor !== null ||
+    (session.kind !== "anonymous" && session.kind !== "expired")
+  ) {
+    invalid("whoami", "inconsistent actor or session state");
+  }
+  return { actor: null, session: { kind: session.kind } };
 }
 
 export function parseAuthPublicConfig(value: unknown): AuthPublicConfig {
diff --git a/web/workspace/src/lib/workspace/auth/page-session.ts b/web/workspace/src/lib/workspace/auth/page-session.ts
new file mode 100644
index 000000000..4ea824ddc
--- /dev/null
+++ b/web/workspace/src/lib/workspace/auth/page-session.ts
@@ -0,0 +1,28 @@
+import { error, redirect } from "@sveltejs/kit";
+import { browserSession, observeBrowserSession } from "./session-state.ts";
+import { isPublicPage, loginUrl } from "./routes.ts";
+
+// root loadとそのparentを待つ各loaderが同じ確認を共有する。
+// SSRは無効。fragmentはHTTP/Serverに依存せず、browserの最終URLから回収する。
+export async function requirePageSession(url: URL): Promise<void> {
+  observeBrowserSession();
+  if (isPublicPage(url.pathname)) return;
+  const snapshot = await browserSession.refresh();
+  if (snapshot !== browserSession.snapshot) return requirePageSession(url);
+  if (snapshot.kind !== "ready") {
+    error(
+      503,
+      "Your session could not be loaded. Login status is unknown. Retry this page.",
+    );
+  }
+  if (snapshot.value.session.kind === "authenticated") return;
+  if (snapshot.value.session.kind === "anonymous") redirect(307, "/");
+  const target = new URL(url);
+  if (
+    typeof location !== "undefined" && location.pathname === url.pathname &&
+    location.search === url.search
+  ) {
+    target.hash = location.hash;
+  }
+  redirect(307, loginUrl(target.pathname + target.search + target.hash));
+}
diff --git a/web/workspace/src/lib/workspace/auth/routes.test.ts b/web/workspace/src/lib/workspace/auth/routes.test.ts
index c80b69926..feee08cd7 100644
--- a/web/workspace/src/lib/workspace/auth/routes.test.ts
+++ b/web/workspace/src/lib/workspace/auth/routes.test.ts
@@ -12,16 +12,16 @@ function assertEquals(
 }
 import { authEntryUrl, loginUrl, safeReturnTo } from "./routes.ts";
 
-Deno.test("return destination permits known app screens without forwarding arbitrary query or fragment", () => {
+Deno.test("return destination preserves query and fragment only on known app screens", () => {
   for (
     const [input, expected] of [
       ["/", "/dashboard"],
-      ["/dashboard?query=discard#fragment", "/dashboard"],
+      ["/dashboard?query=keep#fragment", "/dashboard?query=keep#fragment"],
       ["/account", "/account"],
       ["/account?returnTo=//evil.invalid#secret", "/account"],
       [
         "/w/workspace-id/tickets/T-123?filter=all#entry",
-        "/w/workspace-id/tickets/T-123",
+        "/w/workspace-id/tickets/T-123?filter=all#entry",
       ],
       [
         "/login/device?user_code=ABCD-EFGH",
@@ -31,7 +31,7 @@ Deno.test("return destination permits known app screens without forwarding arbit
         "/login/device?code=abcd-1234&returnTo=//evil.invalid",
         "/login/device?user_code=abcd-1234",
       ],
-      ["/login/device?user_code=%252f%252fevil.invalid", "/login/device"],
+      ["/login/device?user_code=%252f%252fevil.invalid", "/dashboard"],
     ]
   ) assertEquals(safeReturnTo(input), expected, input);
 });
@@ -64,6 +64,11 @@ Deno.test("return destination rejects external, ambiguous encoding and authentic
       "/account\t",
       "/account\u0000",
       "/account%00",
+      "/account?q=%255c",
+      "/account?q=%0A",
+      "/account#%5c",
+      "/account?q=%ZZ",
+      "/account?q=%252f%252fevil.invalid",
       "/api/auth/logout",
       "/hosting/setup",
       "/not-an-app-route",
@@ -86,3 +91,38 @@ Deno.test("login links encode one validated destination and discard nested auth
     "/login?returnTo=%2Fdashboard",
   );
 });
+
+Deno.test("return destination accepts canonical UTF-8 resource slugs but not encoded ASCII or delimiters", () => {
+  const target = `/w/team/tickets/T-123-${
+    encodeURIComponent("未ログイン")
+  }?view=comments#entry-2`;
+  assertEquals(safeReturnTo(target), target);
+  for (
+    const [input, expected] of [
+      [
+        "/w/team/tickets?filter=100%25#entry",
+        "/w/team/tickets?filter=100%25#entry",
+      ],
+      [
+        "/w/team/tickets/%e6%9c%aa?filter=100%25#part%25",
+        "/w/team/tickets/%e6%9c%aa?filter=100%25#part%25",
+      ],
+      [
+        "/w/team/tickets/未?query=a%2fb#entry%2f2",
+        "/w/team/tickets/%E6%9C%AA?query=a%2fb#entry%2f2",
+      ],
+    ]
+  ) {
+    assertEquals(safeReturnTo(input), expected);
+  }
+  for (
+    const input of [
+      "/w/team/tickets/%54-123",
+      "/w/team/tickets/T-123%2fother",
+      "/w/team/tickets/%E0%80%AF",
+      "/w/team/tickets/%252f",
+    ]
+  ) {
+    assertEquals(safeReturnTo(input), "/dashboard");
+  }
+});
diff --git a/web/workspace/src/lib/workspace/auth/routes.ts b/web/workspace/src/lib/workspace/auth/routes.ts
index 595f8d44e..5324ee5a6 100644
--- a/web/workspace/src/lib/workspace/auth/routes.ts
+++ b/web/workspace/src/lib/workspace/auth/routes.ts
@@ -11,13 +11,25 @@ export function safeReturnTo(value: string | null): string {
   }
   const rawPath = value.split(/[?#]/, 1)[0];
   if (
-    rawPath.includes("%") || rawPath.includes("//") ||
+    /%[0-7][0-9a-f]/i.test(rawPath) || rawPath.includes("//") ||
     rawPath.split("/").some((part) => part === "." || part === "..")
   ) {
     return AUTHENTICATED_HOME;
   }
   let url: URL;
+  let decodedPath: string;
   try {
+    decodedPath = decodeURIComponent(rawPath);
+    // pathは一度だけdecodeして許可画面を判定する。UTF-8 escapeの大小や生Unicodeで
+    // origin/区切りは変わらないため、再encodeとの文字列一致は求めない。
+    // query/fragmentはpathの権限を持たないdata。単独の%25は保持し、次のdecodeで
+    // 別文字へ変わる二重escapeとcontrol/backslashだけを拒否する。
+    const decoded = decodeURIComponent(value);
+    if (
+      /[\\\u0000-\u001f\u007f]/u.test(decoded) || /%[0-9a-f]{2}/i.test(decoded)
+    ) {
+      return AUTHENTICATED_HOME;
+    }
     url = new URL(value, "https://app.invalid");
   } catch {
     return AUTHENTICATED_HOME;
@@ -33,9 +45,12 @@ export function safeReturnTo(value: string | null): string {
   }
   if (
     url.pathname === AUTHENTICATED_HOME || url.pathname === "/account" ||
-    /^\/w\/[a-zA-Z0-9_-]+(?:\/[a-zA-Z0-9_/-]*)?$/.test(url.pathname)
+    ["/hosting/settings", "/hosting/accounts"].includes(url.pathname) ||
+    /^\/w\/[a-zA-Z0-9_-]+(?:\/[\p{Letter}\p{Number}_/-]*)?$/u.test(decodedPath)
   ) {
-    return url.pathname;
+    // 認証導線の入れ子は復帰先へ持ち込まない。検索条件とfragmentはURLとして保持する。
+    if (url.searchParams.has("returnTo")) return url.pathname;
+    return url.pathname + url.search + url.hash;
   }
   return AUTHENTICATED_HOME;
 }
@@ -53,7 +68,29 @@ export function authEntryUrl(
   })}`;
 }
 
+export function isPublicPage(path: string): boolean {
+  return [
+    "/",
+    "/login",
+    "/register",
+    "/activate",
+    "/login/device",
+    "/hosting/setup",
+  ]
+    .includes(path);
+}
+
 export function isAuthPage(path: string): boolean {
   return ["/login", "/register", "/account", "/activate", "/login/device"]
     .includes(path);
 }
+
+// Universal loadのURLにfragmentがなくても同じ表示中URLならbrowserから補完する。
+export function browserUrlSuffix(url: URL): string {
+  const hash =
+    typeof location !== "undefined" && location.pathname === url.pathname &&
+      location.search === url.search
+      ? location.hash
+      : url.hash;
+  return url.search + hash;
+}
diff --git a/web/workspace/src/lib/workspace/auth/session-boundary.browser.spec.ts b/web/workspace/src/lib/workspace/auth/session-boundary.browser.spec.ts
new file mode 100644
index 000000000..19bf093ef
--- /dev/null
+++ b/web/workspace/src/lib/workspace/auth/session-boundary.browser.spec.ts
@@ -0,0 +1,121 @@
+// @vitest-environment happy-dom
+import { cleanup, render, screen, waitFor } from "@testing-library/svelte";
+import { afterEach, expect, test, vi } from "vitest";
+import { createRawSnippet } from "svelte";
+import SessionBoundary from "./SessionBoundary.svelte";
+import { browserSession } from "./session-state.ts";
+import { authUser, whoamiPayload } from "./api.test-fixtures.ts";
+import { goto } from "$app/navigation";
+const page = vi.hoisted(() => ({
+  url: new URL("http://localhost:3000/w/team/tickets?q=mine#entry"),
+}));
+vi.mock("$app/state", () => ({ page }));
+vi.mock(
+  "$app/navigation",
+  () => ({ goto: vi.fn(async () => {}), invalidate: vi.fn(async () => {}) }),
+);
+afterEach(() => {
+  cleanup();
+  browserSession.invalidate();
+  vi.unstubAllGlobals();
+  vi.restoreAllMocks();
+  vi.clearAllMocks();
+});
+const actor = { ...authUser, auth_method: "browser_session" };
+const children = createRawSnippet(() => ({
+  render: () => "<p>Private fragment</p>",
+}));
+async function admitted() {
+  window.history.replaceState({}, "", "/w/team/tickets?q=mine#entry");
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async () => Response.json(whoamiPayload(actor))),
+  );
+  await browserSession.refresh();
+  render(SessionBoundary, { children });
+  await screen.findByText("Private fragment");
+}
+
+test("active expired state removes private content and preserves browser query and fragment", async () => {
+  await admitted();
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async () =>
+      Response.json({ actor: null, session: { kind: "expired" } })
+    ),
+  );
+  await browserSession.refresh();
+  await waitFor(() =>
+    expect(screen.queryByText("Private fragment")).toBeNull()
+  );
+  expect(goto).toHaveBeenCalledWith(
+    "/login?returnTo=%2Fw%2Fteam%2Ftickets%3Fq%3Dmine%23entry",
+    { replaceState: true },
+  );
+});
+
+test("unknown state hides and inerts admitted content instead of declaring anonymous", async () => {
+  await admitted();
+  let release!: (response: Response) => void;
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(() =>
+      new Promise<Response>((resolve) => {
+        release = resolve;
+      })
+    ),
+  );
+  const checking = browserSession.refresh();
+  await screen.findByText("Loading session…");
+  expect(screen.getByText("Private fragment").closest("[hidden][inert]"))
+    .toBeTruthy();
+  release(new Response(null, { status: 503 }));
+  await checking;
+  await screen.findByText(
+    "Your session could not be loaded. Login status is unknown.",
+  );
+  expect(screen.getByText("Private fragment").closest("[hidden][inert]"))
+    .toBeTruthy();
+  expect(goto).not.toHaveBeenCalled();
+});
+
+test("another tab changing actor cannot reveal content loaded for the old actor", async () => {
+  await admitted();
+  const reload = vi.spyOn(location, "reload").mockImplementation(() => {});
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async () =>
+      Response.json(
+        whoamiPayload({
+          ...actor,
+          user_id: "different-user",
+          account_id: "different-account",
+        }),
+      )
+    ),
+  );
+  await browserSession.refresh();
+  await waitFor(() => expect(reload).toHaveBeenCalledOnce());
+  expect(screen.queryByText("Private fragment")).toBeNull();
+});
+
+test("a child mount session recheck does not unmount and restart its own loader", async () => {
+  window.history.replaceState({}, "", "/w/team/tickets?q=mine#entry");
+  const fetcher = vi.fn(async () => Response.json(whoamiPayload(actor)));
+  vi.stubGlobal("fetch", fetcher);
+  await browserSession.refresh();
+  let mounts = 0;
+  const checkingChild = createRawSnippet(() => ({
+    render: () => "<p>Mounted session reader</p>",
+    setup: () => {
+      ++mounts;
+      void browserSession.refresh();
+    },
+  }));
+  render(SessionBoundary, { children: checkingChild });
+  await waitFor(() => expect(browserSession.snapshot.kind).toBe("ready"));
+  expect(screen.getByText("Mounted session reader").closest("[hidden]"))
+    .toBeNull();
+  expect(mounts).toBe(1);
+  expect(fetcher).toHaveBeenCalledTimes(2);
+});
diff --git a/web/workspace/src/lib/workspace/auth/session-state.browser.spec.ts b/web/workspace/src/lib/workspace/auth/session-state.browser.spec.ts
new file mode 100644
index 000000000..5ef8ddf6a
--- /dev/null
+++ b/web/workspace/src/lib/workspace/auth/session-state.browser.spec.ts
@@ -0,0 +1,102 @@
+// @vitest-environment happy-dom
+// whoami境界だけを代替し、epoch競合/再確認契機を決定的に検査する。
+// cookieと実storeの一致はServer/browser結合suiteが所有する。
+import { afterEach, expect, test, vi } from "vitest";
+import { SessionState } from "./session-state.ts";
+import type { WhoamiResponse } from "./model.ts";
+import { authUser } from "./api.test-fixtures.ts";
+
+const states: SessionState[] = [];
+afterEach(() => {
+  for (const state of states.splice(0)) state.dispose();
+  vi.useRealTimers();
+  localStorage.clear();
+});
+const anonymous: WhoamiResponse = {
+  actor: null,
+  session: { kind: "anonymous" },
+};
+const expired: WhoamiResponse = { actor: null, session: { kind: "expired" } };
+const authenticated = (
+  expires_at: string | null = "2099-01-01T00:00:00Z",
+): WhoamiResponse => ({
+  actor: { ...authUser, auth_method: "browser_session" },
+  session: { kind: "authenticated", expires_at },
+});
+function gate<T>() {
+  let resolve!: (value: T) => void;
+  const promise = new Promise<T>((done) => {
+    resolve = done;
+  });
+  return { promise, resolve };
+}
+function state(read: () => Promise<WhoamiResponse>) {
+  const result = new SessionState(read);
+  states.push(result);
+  return result;
+}
+
+test("concurrent session checks share one authoritative read without classifying loading as anonymous", async () => {
+  const response = gate<WhoamiResponse>();
+  const read = vi.fn(() => response.promise);
+  const session = state(read);
+  const first = session.refresh();
+  const second = session.refresh();
+  expect(session.snapshot.kind).toBe("loading");
+  expect(read).toHaveBeenCalledTimes(1);
+  response.resolve(expired);
+  await Promise.all([first, second]);
+  expect(session.snapshot).toEqual({ kind: "ready", value: expired });
+});
+
+test("delayed expired response cannot replace a new login in the same tab", async () => {
+  const older = gate<WhoamiResponse>();
+  const read = vi.fn<() => Promise<WhoamiResponse>>().mockReturnValueOnce(
+    older.promise,
+  ).mockResolvedValue(authenticated());
+  const session = state(read);
+  const first = session.refresh();
+  session.invalidate();
+  await session.refresh();
+  older.resolve(expired);
+  await first;
+  expect(session.snapshot).toEqual({ kind: "ready", value: authenticated() });
+});
+
+test("storage generation fences responses even before the other tab storage event is delivered", async () => {
+  const older = gate<WhoamiResponse>();
+  const read = vi.fn<() => Promise<WhoamiResponse>>().mockReturnValueOnce(
+    older.promise,
+  ).mockResolvedValue(authenticated());
+  const session = state(read);
+  const first = session.refresh();
+  localStorage.setItem(
+    "yoi.browser-auth-generation",
+    JSON.stringify({ id: "new-login", reason: "authentication" }),
+  );
+  older.resolve(expired);
+  await first;
+  expect(session.snapshot).toEqual({ kind: "ready", value: authenticated() });
+});
+
+test("active deadline rechecks the server and reports failures as unknown, never inferred expiry", async () => {
+  vi.useFakeTimers();
+  const read = vi.fn<() => Promise<WhoamiResponse>>().mockResolvedValueOnce(
+    authenticated(new Date(Date.now() + 5_000).toISOString()),
+  ).mockRejectedValueOnce(new Error("network")).mockResolvedValue(expired);
+  const session = state(read);
+  await session.refresh();
+  await vi.advanceTimersByTimeAsync(5_000);
+  expect(session.snapshot).toEqual({ kind: "error" });
+  await session.refresh();
+  expect(session.snapshot).toEqual({ kind: "ready", value: expired });
+});
+
+test("a challenge failure is not session expiry; recheck may still be authenticated or anonymous", async () => {
+  for (const value of [authenticated(), anonymous]) {
+    const session = state(async () => value);
+    session.invalidate();
+    await session.refresh();
+    expect(session.snapshot).toEqual({ kind: "ready", value });
+  }
+});
diff --git a/web/workspace/src/lib/workspace/auth/session-state.ts b/web/workspace/src/lib/workspace/auth/session-state.ts
new file mode 100644
index 000000000..2ff372940
--- /dev/null
+++ b/web/workspace/src/lib/workspace/auth/session-state.ts
@@ -0,0 +1,153 @@
+/// <reference lib="dom" />
+import { loadWhoami } from "./api.ts";
+import type { WhoamiResponse } from "./model.ts";
+
+export type SessionSnapshot =
+  | { kind: "loading" }
+  | { kind: "error" }
+  | { kind: "ready"; value: WhoamiResponse };
+
+// 世代は権限ではなく、認証操作より前に開始した応答を捨てるためだけに使う。
+// Cookieの実状態は常にwhoamiが所有し、tab間通知や一般401からexpiredを推測しない。
+const GENERATION_KEY = "yoi.browser-auth-generation";
+export class SessionState {
+  snapshot: SessionSnapshot = { kind: "loading" };
+  private generation = 0;
+  private pending: Promise<SessionSnapshot> | null = null;
+  private listeners = new Set<(state: SessionSnapshot) => void>();
+  private timer: ReturnType<typeof setTimeout> | undefined;
+
+  get authenticationGeneration(): number {
+    return this.generation;
+  }
+
+  constructor(private readonly read = loadWhoami) {}
+
+  subscribe(listener: (state: SessionSnapshot) => void): () => void {
+    this.listeners.add(listener);
+    listener(this.snapshot);
+    return () => this.listeners.delete(listener);
+  }
+
+  private publish(snapshot: SessionSnapshot): void {
+    this.snapshot = snapshot;
+    clearTimeout(this.timer);
+    if (
+      snapshot.kind === "ready" &&
+      snapshot.value.session.kind === "authenticated"
+    ) {
+      const expiry = snapshot.value.session.expires_at;
+      if (expiry !== null) {
+        // Timerは再照会の契機。local clockだけで期限切れと断定しない。
+        const remaining = Date.parse(expiry) - Date.now();
+        this.timer = setTimeout(() => {
+          void this.refresh();
+        }, Math.min(2_147_483_647, Math.max(1_000, remaining)));
+      }
+    }
+    for (const listener of this.listeners) listener(snapshot);
+  }
+
+  invalidate(): void {
+    ++this.generation;
+    this.pending = null;
+    this.publish({ kind: "loading" });
+  }
+
+  async refresh(): Promise<SessionSnapshot> {
+    if (this.pending) return this.pending;
+    const generation = this.generation;
+    const stamp = storageStamp();
+    this.publish({ kind: "loading" });
+    const pending = (async () => {
+      let result: SessionSnapshot;
+      try {
+        result = { kind: "ready", value: await this.read() };
+      } catch {
+        result = { kind: "error" };
+      }
+      if (generation !== this.generation || stamp !== storageStamp()) {
+        // 新世代が既に確定していれば再取得すら不要。古い完了で確定結果を巻き戻さない。
+        if (generation !== this.generation) {
+          if (this.pending) return await this.pending;
+          if (this.snapshot.kind !== "loading") return this.snapshot;
+        }
+        // 別tabの操作がstorage eventより先に完了していても古い応答を採用しない。
+        if (generation === this.generation) this.invalidate();
+        return await this.refresh();
+      }
+      this.pending = null;
+      this.publish(result);
+      return result;
+    })();
+    this.pending = pending;
+    return pending;
+  }
+
+  dispose(): void {
+    clearTimeout(this.timer);
+    this.listeners.clear();
+    ++this.generation;
+  }
+}
+
+function storageStamp(): string | null {
+  try {
+    return globalThis.localStorage?.getItem(GENERATION_KEY) ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export const browserSession = new SessionState();
+
+export function sessionMutation(
+  reason: "authentication" | "logout" = "authentication",
+): void {
+  browserSession.invalidate();
+  const message = JSON.stringify({ id: crypto.randomUUID(), reason });
+  try {
+    localStorage.setItem(GENERATION_KEY, message);
+  } catch { /* 保存拒否でも同tab fenceは維持。 */ }
+  if (reason === "logout") clearReturnTo();
+}
+
+export const CLEAR_RETURN_EVENT = "yoi:clear-auth-return";
+function clearReturnTo(): void {
+  if (typeof window !== "undefined") {
+    window.dispatchEvent(new Event(CLEAR_RETURN_EVENT));
+  }
+}
+
+let installed = false;
+export function recheckAfterUnauthorized(
+  authenticationGeneration: number,
+): void {
+  if (
+    installed &&
+    authenticationGeneration === browserSession.authenticationGeneration
+  ) void browserSession.refresh();
+}
+export function observeBrowserSession(): void {
+  if (installed || typeof window === "undefined") return;
+  installed = true;
+  const refresh = () => {
+    void browserSession.refresh();
+  };
+  window.addEventListener("focus", refresh);
+  window.addEventListener("pageshow", refresh);
+  document.addEventListener("visibilitychange", () => {
+    if (!document.hidden) refresh();
+  });
+  window.addEventListener("storage", (event) => {
+    if (event.key !== GENERATION_KEY && event.key !== null) return;
+    browserSession.invalidate();
+    try {
+      if (
+        event.key === null ||
+        JSON.parse(event.newValue ?? "null")?.reason === "logout"
+      ) clearReturnTo();
+    } catch { /* 不明な通知も権限ではなく再照会だけ。 */ }
+    refresh();
+  });
+}
diff --git a/web/workspace/src/lib/workspace/auth/session.browser.spec.ts b/web/workspace/src/lib/workspace/auth/session.browser.spec.ts
index b892e0086..559b97782 100644
--- a/web/workspace/src/lib/workspace/auth/session.browser.spec.ts
+++ b/web/workspace/src/lib/workspace/auth/session.browser.spec.ts
@@ -1,5 +1,6 @@
 // @vitest-environment happy-dom
 import { afterEach, expect, test, vi } from "vitest";
+import { browserSession, sessionMutation } from "./session-state.ts";
 import { BrowserAuth } from "./browser-session.svelte.ts";
 import { addPasskey, loginWithPasskey, logout } from "./api.ts";
 import { SESSION_CHANGED_EVENT } from "./hosting.ts";
@@ -13,6 +14,7 @@ import {
 const sessions: BrowserAuth[] = [];
 afterEach(() => {
   for (const auth of sessions.splice(0)) auth.dispose();
+  browserSession.invalidate();
   vi.unstubAllGlobals();
   vi.restoreAllMocks();
 });
@@ -33,6 +35,9 @@ function session() {
 
 function whoami(authenticated: boolean) {
   return Response.json({
+    session: authenticated
+      ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+      : { kind: "anonymous" },
     actor: authenticated
       ? { ...authUser, auth_method: "browser_session" }
       : null,
@@ -98,7 +103,11 @@ test("loading and failed whoami are not anonymous readiness and cannot start aut
   expect(await auth.run("pending", "done", operation)).toBe(false);
   expect(operation).not.toHaveBeenCalled();
   await auth.refresh();
-  expect(auth.session).toEqual({ kind: "ready", actor: null });
+  expect(auth.session).toEqual({
+    kind: "ready",
+    actor: null,
+    session: { kind: "anonymous" },
+  });
 });
 
 for (
@@ -117,6 +126,7 @@ for (
     );
     const auth = session();
     const first = auth.refresh();
+    browserSession.invalidate();
     const second = auth.refresh();
     latest.resolve(
       latestStatus === 200
@@ -146,13 +156,21 @@ test("a delayed pre-logout whoami cannot resurrect the previous actor", async ()
   const oldResponse = gate<Response>();
   fetcher.mockReturnValueOnce(oldResponse.promise);
   const oldRefresh = auth.refresh();
-  await auth.refresh();
-  expect(auth.actor?.handle).toBe("alice");
-  expect(await auth.run("Logging out", "Logged out", logout)).toBe(true);
-  expect(auth.session).toEqual({ kind: "ready", actor: null });
+  expect(await auth.run("Logging out", "Logged out", logout, "logout")).toBe(
+    true,
+  );
+  expect(auth.session).toEqual({
+    kind: "ready",
+    actor: null,
+    session: { kind: "anonymous" },
+  });
   oldResponse.resolve(whoami(true));
   await oldRefresh;
-  expect(auth.session).toEqual({ kind: "ready", actor: null });
+  expect(auth.session).toEqual({
+    kind: "ready",
+    actor: null,
+    session: { kind: "anonymous" },
+  });
   expect(auth.status).toBe("Logged out");
 });
 
@@ -190,7 +208,7 @@ test("busy login rejects duplicate operations and refresh until its post-complet
   options.resolve(Response.json(loginOptions));
   await confirmingStarted.promise;
   expect(auth.busy).toBe(true);
-  expect(auth.session.kind).toBe("loading");
+  expect(auth.session.kind).toBe("ready");
   expect(await auth.run("duplicate", "incorrect", duplicate)).toBe(false);
   await auth.refresh();
   expect(paths(fetcher).filter((path) => path === "/api/auth/whoami"))
@@ -220,7 +238,7 @@ for (const status of [400, 401, 410]) {
     expect(auth.status).toBe("");
     expect(auth.error).toMatch(
       status === 401
-        ? /Your session or authentication challenge expired/
+        ? /Authentication request was rejected/
         : /The request or authentication challenge is invalid or expired/,
     );
     expect(auth.session.kind).toBe("ready");
@@ -270,7 +288,11 @@ for (
     expect(auth.error).not.toContain("secret credential detail");
     expect(auth.status).toBe("");
     expect(auth.busy).toBe(false);
-    expect(auth.session).toEqual({ kind: "ready", actor: null });
+    expect(auth.session).toEqual({
+      kind: "ready",
+      actor: null,
+      session: { kind: "anonymous" },
+    });
     expect(paths(fetcher)).toEqual([
       "/api/auth/whoami",
       "/api/auth/passkeys/login/options",
@@ -338,7 +360,7 @@ for (const rejected of [false, true]) {
   });
 }
 
-test("dispose aborts WebAuthn and ignores a late credential without completion, session notification or refresh", async () => {
+test("dispose aborts WebAuthn without accepting late credentials, while shared session is rechecked", async () => {
   const { fetcher, get } = boundary();
   const auth = session();
   await auth.refresh();
@@ -360,12 +382,17 @@ test("dispose aborts WebAuthn and ignores a late credential without completion,
   expect(signal.aborted).toBe(true);
   credential.resolve(credentialFixture(true));
   expect(await run).toBe(false);
-  expect(auth.session).toEqual({ kind: "ready", actor: null });
+  expect(auth.session).toEqual({
+    kind: "ready",
+    actor: null,
+    session: { kind: "anonymous" },
+  });
   expect(auth.status).toBe("Waiting");
   expect(auth.error).toBe("");
   expect(paths(fetcher)).toEqual([
     "/api/auth/whoami",
     "/api/auth/passkeys/login/options",
+    "/api/auth/whoami",
   ]);
   expect(
     dispatch.mock.calls.filter(([event]) =>
@@ -409,6 +436,7 @@ test("dispose ignores a completion response even when the HTTP boundary does not
     "/api/auth/whoami",
     "/api/auth/passkeys/login/options",
     "/api/auth/passkeys/login/complete",
+    "/api/auth/whoami",
   ]);
   expect(
     dispatch.mock.calls.filter(([event]) =>
@@ -443,15 +471,73 @@ test("dispose during the post-operation whoami prevents its late actor from beco
     (signal) => loginWithPasskey(signal),
   );
   await started.promise;
-  expect(auth.session.kind).toBe("loading");
+  expect(auth.session.kind).toBe("ready");
   expect(auth.busy).toBe(true);
   auth.dispose();
   response.resolve(whoami(true));
   expect(await run).toBe(false);
-  expect(auth.session.kind).toBe("loading");
+  expect(auth.session.kind).toBe("ready");
   expect(auth.actor).toBeNull();
 });
 
+for (const newer of ["logout", "another-actor"] as const) {
+  test(`confirmation superseded by ${newer} cannot report success or navigate using the old return URL`, async () => {
+    const { fetcher } = boundary();
+    const auth = session();
+    await auth.refresh();
+    const confirming = gate<Response>();
+    const started = gate<void>();
+    const request = fetcher.getMockImplementation()!;
+    fetcher.mockImplementation((input, init) => {
+      if (String(input) === "/api/auth/whoami") {
+        started.resolve();
+        return confirming.promise;
+      }
+      return request(input, init);
+    });
+    const changed = vi.fn();
+    window.addEventListener(SESSION_CHANGED_EVENT, changed);
+    const navigate = vi.fn();
+    try {
+      const run = auth.run("Waiting", "Logged in", loginWithPasskey).then(
+        (confirmed) => {
+          if (confirmed && auth.actor) navigate("/account?old=return#entry");
+          return confirmed;
+        },
+      );
+      await started.promise;
+      sessionMutation(newer === "logout" ? "logout" : "authentication");
+      fetcher.mockResolvedValueOnce(
+        newer === "logout" ? whoami(false) : Response.json({
+          actor: {
+            ...authUser,
+            user_id: "other-user",
+            account_id: "other-account",
+            handle: "bob",
+            auth_method: "browser_session",
+          },
+          session: {
+            kind: "authenticated",
+            expires_at: "2099-01-01T00:00:00Z",
+          },
+        }),
+      );
+      await browserSession.refresh();
+      confirming.resolve(whoami(true));
+      expect(await run).toBe(false);
+      expect(auth.actor?.handle ?? null).toBe(
+        newer === "logout" ? null : "bob",
+      );
+      expect(auth.status).toBe("");
+      expect(auth.busy).toBe(false);
+      expect(changed).not.toHaveBeenCalled();
+      expect(navigate).not.toHaveBeenCalled();
+    } finally {
+      window.removeEventListener(SESSION_CHANGED_EVENT, changed);
+    }
+  });
+}
+
 for (const purpose of ["login", "addition"] as const) {
   test(`${purpose} null credential reports cancellation and never sends completion`, async () => {
     const { fetcher, get, create } = boundary(purpose === "addition");
diff --git a/web/workspace/src/lib/workspace/navigation/deferred.test.ts b/web/workspace/src/lib/workspace/navigation/deferred.test.ts
index 238567212..63b3c85cc 100644
--- a/web/workspace/src/lib/workspace/navigation/deferred.test.ts
+++ b/web/workspace/src/lib/workspace/navigation/deferred.test.ts
@@ -21,6 +21,7 @@ Deno.test("deferred load returns before API completion and snapshots navigation
   const api = gate<string>();
   const event = {
     params: { id: "first" },
+    parent: async () => ({}),
     url: new URL("https://example.test/first?q=old"),
   };
   const load = deferPage(async ({ params, url }: typeof event) => ({
@@ -54,9 +55,12 @@ Deno.test("deferred redirects and HTTP failures are handled results, not unhandl
       ],
     ] as const
   ) {
-    const load = deferPage((_event: { params: {}; url: URL }) => run());
+    const load = deferPage((
+      _event: { params: {}; url: URL; parent: () => Promise<unknown> },
+    ) => run());
     const result = await load({
       params: {},
+      parent: async () => ({}),
       url: new URL("https://example.test/"),
     }).deferredPage;
     assert(
@@ -94,3 +98,39 @@ Deno.test("resolved data preserves page overrides without waiting for the global
       result.data.workspaceId === "team",
   );
 });
+
+Deno.test("private deferred loader starts only after parent admission and never on parent failure", async () => {
+  for (const outcome of ["admit", "anonymous", "expired", "error"] as const) {
+    const admission = gate<void>();
+    let calls = 0;
+    const load = deferPage(
+      async (
+        _event: { params: {}; url: URL; parent: () => Promise<unknown> },
+      ) => {
+        ++calls;
+        return {};
+      },
+    );
+    const result = load({
+      params: {},
+      url: new URL("https://app.invalid/w/a/tickets"),
+      parent: async () => {
+        await admission.promise;
+        if (outcome === "anonymous") redirect(307, "/");
+        if (outcome === "expired") {
+          redirect(307, "/login?returnTo=%2Fw%2Fa%2Ftickets");
+        }
+        if (outcome === "error") {
+          error(503, "Unknown session");
+        }
+        return {};
+      },
+    });
+    await Promise.resolve();
+    assert(calls === 0);
+    admission.release();
+    const settled = await result.deferredPage;
+    assert(calls === (outcome === "admit" ? 1 : 0));
+    assert(settled.ok === (outcome === "admit"));
+  }
+});
diff --git a/web/workspace/src/lib/workspace/navigation/deferred.ts b/web/workspace/src/lib/workspace/navigation/deferred.ts
index c3baaf145..6e71ab849 100644
--- a/web/workspace/src/lib/workspace/navigation/deferred.ts
+++ b/web/workspace/src/lib/workspace/navigation/deferred.ts
@@ -39,7 +39,11 @@ export async function settle<T>(
 }
 
 export function deferPage<
-  E extends { params: Record<string, string | undefined>; url: URL },
+  E extends {
+    params: Record<string, string | undefined>;
+    url: URL;
+    parent: () => Promise<unknown>;
+  },
   T extends object,
 >(
   loader: (event: E) => T | Promise<T>,
@@ -51,11 +55,13 @@ export function deferPage<
       params: { ...event.params },
       url: new URL(event.url.href),
     };
-    try {
-      return { deferredPage: settle(loader(snapshot)) };
-    } catch (error) {
-      return { deferredPage: settle(Promise.reject(error)) };
-    }
+    // SvelteKitはparent/childを並列開始する。deferしても認証前fetchを開始しない。
+    return {
+      deferredPage: settle((async () => {
+        await snapshot.parent();
+        return await loader(snapshot);
+      })()),
+    };
   };
 }
 
diff --git a/web/workspace/src/lib/workspace/sidebar/hosting-navigation.browser.spec.ts b/web/workspace/src/lib/workspace/sidebar/hosting-navigation.browser.spec.ts
index 905d3fe88..695e5841f 100644
--- a/web/workspace/src/lib/workspace/sidebar/hosting-navigation.browser.spec.ts
+++ b/web/workspace/src/lib/workspace/sidebar/hosting-navigation.browser.spec.ts
@@ -18,6 +18,9 @@ for (
     const fetcher = vi.fn<typeof fetch>().mockImplementation(async (input) => {
       if (String(input) === "/api/auth/whoami") {
         return Response.json({
+          session: actor
+            ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+            : { kind: "anonymous" },
           actor: actor ? { ...authUser, auth_method: "browser_session" } : null,
         });
       }
diff --git a/web/workspace/src/routes/+layout.svelte b/web/workspace/src/routes/+layout.svelte
index 401c24047..bbaab7c93 100644
--- a/web/workspace/src/routes/+layout.svelte
+++ b/web/workspace/src/routes/+layout.svelte
@@ -4,6 +4,7 @@
   // navigationの構成はWorkspace identityやpermissionの根拠にはしない。
   // Header下辺とSidebar右辺だけで領域境界を示し、viewport外周に線を重ねない。
   // MobileはSidebarがHeader下を占有する間mainをinertにし、隠れた内容へfocusを入れない。
+  import SessionBoundary from '#lib/workspace/auth/SessionBoundary.svelte';
   import { page } from '$app/state';
   import { setContext } from 'svelte';
   import { MediaQuery } from 'svelte/reactivity';
@@ -96,6 +97,7 @@
   });
 </script>
 
+<SessionBoundary>
 {#if standalone}
   <main class="standalone-main">
     {@render children()}
@@ -147,6 +149,7 @@
   </main>
 </div>
 {/if}
+</SessionBoundary>
 
 <style>
   .standalone-main {
diff --git a/web/workspace/src/routes/+layout.ts b/web/workspace/src/routes/+layout.ts
index 6b013c40c..9f37d776f 100644
--- a/web/workspace/src/routes/+layout.ts
+++ b/web/workspace/src/routes/+layout.ts
@@ -1,3 +1,4 @@
+import { requirePageSession } from "#lib/workspace/auth/page-session.ts";
 import { isAuthPage } from "#lib/workspace/auth/routes.ts";
 import { listWorkspaces } from "#lib/workspace/api/workspace-catalog.ts";
 import { settle } from "#lib/workspace/navigation/deferred.ts";
@@ -5,28 +6,33 @@ import type { Load } from "@sveltejs/kit";
 
 export const ssr = false;
 
-export const load = ({ fetch, url }: Parameters<Load>[0]) => ({
-  deferredCatalog: settle((async () => {
-    // 公開入口・認証・hostingの判断はWorkspace catalogを必要としない。
-    // dashboardはactor確認後に自身の一覧を取得する。
-    if (
-      url.pathname === "/" || url.pathname === "/dashboard" ||
-      isAuthPage(url.pathname) || url.pathname.startsWith("/hosting/")
-    ) {
-      return { accessibleWorkspaces: [], workspaceCatalogError: null };
-    }
-    try {
-      return {
-        accessibleWorkspaces: await listWorkspaces(fetch),
-        workspaceCatalogError: null,
-      };
-    } catch (error) {
-      return {
-        accessibleWorkspaces: [],
-        workspaceCatalogError: error instanceof Error
-          ? error.message
-          : "Unable to load Workspaces",
-      };
-    }
-  })()),
-});
+export const load = async ({ fetch, url, depends }: Parameters<Load>[0]) => {
+  depends("auth:session");
+  // href依存でquery変更を含むSPA遷移でもrootの認証gateを再実行する。
+  await requirePageSession(new URL(url.href));
+  return {
+    deferredCatalog: settle((async () => {
+      // 公開入口・認証・hostingの判断はWorkspace catalogを必要としない。
+      // dashboardはactor確認後に自身の一覧を取得する。
+      if (
+        url.pathname === "/" || url.pathname === "/dashboard" ||
+        isAuthPage(url.pathname) || url.pathname.startsWith("/hosting/")
+      ) {
+        return { accessibleWorkspaces: [], workspaceCatalogError: null };
+      }
+      try {
+        return {
+          accessibleWorkspaces: await listWorkspaces(fetch),
+          workspaceCatalogError: null,
+        };
+      } catch (error) {
+        return {
+          accessibleWorkspaces: [],
+          workspaceCatalogError: error instanceof Error
+            ? error.message
+            : "Unable to load Workspaces",
+        };
+      }
+    })()),
+  };
+};
diff --git a/web/workspace/src/routes/account/+page.svelte b/web/workspace/src/routes/account/+page.svelte
index a1501e5ec..09dacabe6 100644
--- a/web/workspace/src/routes/account/+page.svelte
+++ b/web/workspace/src/routes/account/+page.svelte
@@ -9,9 +9,6 @@
   const auth = new BrowserAuth();
   async function refresh() {
     await auth.refresh();
-    if (auth.session.kind === 'ready' && !auth.actor) {
-      await goto(loginUrl('/account'), { replaceState: true });
-    }
   }
   async function add() {
     if (!auth.actor) return;
@@ -19,8 +16,8 @@
   }
   async function signOut() {
     if (!auth.actor) return;
-    const confirmed = await auth.run('Logging out…', 'Logged out.', logout);
-    if (confirmed && !auth.actor) await goto(loginUrl('/account'), { replaceState: true });
+    const confirmed = await auth.run('Logging out…', 'Logged out.', logout, 'logout');
+    if (confirmed && !auth.actor) await goto('/', { replaceState: true });
   }
   onMount(() => { void refresh(); return () => auth.dispose(); });
 </script>
diff --git a/web/workspace/src/routes/account/account.browser.spec.ts b/web/workspace/src/routes/account/account.browser.spec.ts
index cd51302e6..caf68c1fb 100644
--- a/web/workspace/src/routes/account/account.browser.spec.ts
+++ b/web/workspace/src/routes/account/account.browser.spec.ts
@@ -6,6 +6,7 @@ import {
   screen,
   waitFor,
 } from "@testing-library/svelte";
+import { browserSession } from "#lib/workspace/auth/session-state.ts";
 import { afterEach, expect, test, vi } from "vitest";
 import { tick } from "svelte";
 import { goto } from "$app/navigation";
@@ -26,6 +27,7 @@ vi.mock("$app/state", () => ({ page }));
 
 afterEach(() => {
   cleanup();
+  browserSession.invalidate();
   vi.unstubAllGlobals();
   vi.clearAllMocks();
   page.url = new URL("https://example.test/login");
@@ -61,6 +63,9 @@ function boundary({
         return new Response(null, { status: state.whoamiStatus });
       }
       return Response.json({
+        session: state.authenticated
+          ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+          : { kind: "anonymous" },
         actor: state.authenticated
           ? { ...authUser, auth_method: "browser_session" }
           : null,
@@ -187,7 +192,10 @@ for (
   const [returnTo, expected] of [
     [null, "/dashboard"],
     ["/account", "/account"],
-    ["/w/project/tickets?ignored=1#fragment", "/w/project/tickets"],
+    [
+      "/w/project/tickets?ignored=1#fragment",
+      "/w/project/tickets?ignored=1#fragment",
+    ],
     [
       "/login/device?code=abcd-EFGH&untrusted=1",
       "/login/device?user_code=abcd-EFGH",
@@ -396,14 +404,11 @@ test("account displays the current identity without editable target fields and a
   expect(goto).not.toHaveBeenCalled();
 });
 
-test("anonymous account redirects to login with an account return path and has no credential inputs", async () => {
+test("account fragment leaves anonymous navigation to the root gate and has no credential inputs", async () => {
   const { fetcher } = boundary();
   render(Account);
-  await waitFor(() =>
-    expect(goto).toHaveBeenCalledWith("/login?returnTo=%2Faccount", {
-      replaceState: true,
-    })
-  );
+  await screen.findByRole("link", { name: "Log in to your account" });
+  expect(goto).not.toHaveBeenCalled();
   expect(
     screen.getByRole("link", { name: "Log in to your account" }).getAttribute(
       "href",
@@ -468,12 +473,12 @@ test("unknown account session shows retry instead of treating errors as anonymou
   expect(goto).not.toHaveBeenCalled();
 });
 
-test("logout posts to the session endpoint and confirms anonymous whoami before login navigation", async () => {
+test("logout confirms the server session is cleared and returns to the public home", async () => {
   const { fetcher } = boundary({ authenticated: true });
   render(Account);
   await fireEvent.click(await screen.findByRole("button", { name: "Log out" }));
   await waitFor(() =>
-    expect(goto).toHaveBeenCalledWith("/login?returnTo=%2Faccount", {
+    expect(goto).toHaveBeenCalledWith("/", {
       replaceState: true,
     })
   );
@@ -494,7 +499,7 @@ test("expired addition revokes stale identity without silently retrying as regis
   await fireEvent.click(
     await screen.findByRole("button", { name: "Add passkey to alice" }),
   );
-  await screen.findByText(/Your session or authentication challenge expired/);
+  await screen.findByText(/Authentication request was rejected/);
   await screen.findByRole("link", { name: "Log in to your account" });
   expect(screen.queryByRole("button", { name: /Add passkey/ })).toBeNull();
   expect(screen.queryByText("Passkey added to your account.")).toBeNull();
@@ -676,7 +681,7 @@ for (const status of [401, 410]) {
     );
     await screen.findByText(
       status === 401
-        ? /Your session or authentication challenge expired/
+        ? /Authentication request was rejected/
         : /The request or authentication challenge is invalid or expired/,
     );
     expect(
diff --git a/web/workspace/src/routes/entry.browser.spec.ts b/web/workspace/src/routes/entry.browser.spec.ts
index 6c0db5247..cc0b06ad1 100644
--- a/web/workspace/src/routes/entry.browser.spec.ts
+++ b/web/workspace/src/routes/entry.browser.spec.ts
@@ -8,6 +8,7 @@ import {
   waitFor,
 } from "@testing-library/svelte";
 import { afterEach, expect, test, vi } from "vitest";
+import { browserSession } from "#lib/workspace/auth/session-state.ts";
 import Home from "./+page.svelte";
 import Dashboard from "./dashboard/+page.svelte";
 import { authUser } from "#lib/workspace/auth/api.test-fixtures.ts";
@@ -20,6 +21,7 @@ import { goto } from "$app/navigation";
 vi.mock("$app/navigation", () => ({ goto: vi.fn(async () => {}) }));
 afterEach(() => {
   cleanup();
+  browserSession.invalidate();
   vi.unstubAllGlobals();
   vi.clearAllMocks();
 });
@@ -51,6 +53,9 @@ function boundary() {
         if (state.sessionGate) return state.sessionGate.promise;
         return state.whoamiStatus === 200
           ? Response.json({
+            session: state.signedIn
+              ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+              : { kind: "anonymous" },
             actor: state.signedIn
               ? {
                 ...authUser,
@@ -288,7 +293,10 @@ test("same actor focus retains creation disclosure, repository fields, errors an
   await screen.findByText("Loading session…");
   expect(screen.queryByLabelText("Workspace display name")).toBeNull();
   state.sessionGate.resolve(
-    Response.json({ actor: { ...authUser, auth_method: "browser_session" } }),
+    Response.json({
+      session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+      actor: { ...authUser, auth_method: "browser_session" },
+    }),
   );
   expect(
     (await screen.findByLabelText("Workspace display name") as HTMLInputElement)
@@ -323,7 +331,10 @@ test("pending create remains single across focus and a success during unknown se
   await waitFor(() => expect(response.bodyUsed).toBe(true));
   expect(goto).not.toHaveBeenCalled();
   state.sessionGate.resolve(
-    Response.json({ actor: { ...authUser, auth_method: "browser_session" } }),
+    Response.json({
+      session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+      actor: { ...authUser, auth_method: "browser_session" },
+    }),
   );
   expect(
     (await screen.findByRole("link", { name: "Open created Workspace" }))
diff --git a/web/workspace/src/routes/hosting/accounts/accounts.browser.spec.ts b/web/workspace/src/routes/hosting/accounts/accounts.browser.spec.ts
index 36a492ff4..1d2bed0e8 100644
--- a/web/workspace/src/routes/hosting/accounts/accounts.browser.spec.ts
+++ b/web/workspace/src/routes/hosting/accounts/accounts.browser.spec.ts
@@ -6,11 +6,13 @@ import {
   screen,
   waitFor,
 } from "@testing-library/svelte";
+import { browserSession } from "#lib/workspace/auth/session-state.ts";
 import { afterEach, expect, test, vi } from "vitest";
 import Accounts from "./+page.svelte";
 import { authUser } from "#lib/workspace/auth/api.test-fixtures.ts";
 afterEach(() => {
   cleanup();
+  browserSession.invalidate();
   vi.unstubAllGlobals();
 });
 function boundary(
@@ -20,6 +22,9 @@ function boundary(
   const fetcher = vi.fn<typeof fetch>(async (input, init) => {
     if (input === "/api/auth/whoami") {
       return Response.json({
+        session: mode !== "anonymous"
+          ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+          : { kind: "anonymous" },
         actor: mode === "anonymous"
           ? null
           : { ...authUser, auth_method: "browser_session" },
diff --git a/web/workspace/src/routes/hosting/settings/settings.browser.spec.ts b/web/workspace/src/routes/hosting/settings/settings.browser.spec.ts
index 1306ad80b..334f15e30 100644
--- a/web/workspace/src/routes/hosting/settings/settings.browser.spec.ts
+++ b/web/workspace/src/routes/hosting/settings/settings.browser.spec.ts
@@ -6,12 +6,14 @@ import {
   screen,
   waitFor,
 } from "@testing-library/svelte";
+import { browserSession } from "#lib/workspace/auth/session-state.ts";
 import { afterEach, expect, test, vi } from "vitest";
 import Settings from "./+page.svelte";
 import { authUser } from "#lib/workspace/auth/api.test-fixtures.ts";
 
 afterEach(() => {
   cleanup();
+  browserSession.invalidate();
   vi.unstubAllGlobals();
 });
 
@@ -25,6 +27,9 @@ function boundary(
       const path = String(input);
       if (path === "/api/auth/whoami") {
         return Response.json({
+          session: persona !== "anonymous"
+            ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+            : { kind: "anonymous" },
           actor: persona === "anonymous"
             ? null
             : { ...authUser, auth_method: "browser_session" },
diff --git a/web/workspace/src/routes/hosting/setup/+page.svelte b/web/workspace/src/routes/hosting/setup/+page.svelte
index 4a218f40c..229311376 100644
--- a/web/workspace/src/routes/hosting/setup/+page.svelte
+++ b/web/workspace/src/routes/hosting/setup/+page.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
   import { onDestroy } from 'svelte';
+  import { browserSession, sessionMutation } from "#lib/workspace/auth/session-state.ts";
   import { loadWhoami, loginWithPasskey } from '#lib/workspace/auth/api.ts';
   import { enrollHostingPasskey } from '#lib/workspace/auth/hosting-enrollment.ts';
   import { loadHostingAccess, notifySessionChanged } from '#lib/workspace/auth/hosting.ts';
@@ -45,6 +46,7 @@
     const expected = user;
     busy = true;
     error = '';
+    sessionMutation();
     try {
       const signedIn = await loginWithPasskey(controller.signal);
       if (!active) return;
@@ -57,6 +59,8 @@
     } catch {
       if (active) error = 'Passkey login or hosting administrator access could not be verified. Try signing in again, or ask the host operator to check this account.';
     } finally {
+      sessionMutation();
+      await browserSession.refresh();
       if (active) busy = false;
     }
   }
diff --git a/web/workspace/src/routes/hosting/setup/hosting-setup.browser.spec.ts b/web/workspace/src/routes/hosting/setup/hosting-setup.browser.spec.ts
index 7e8a869e0..467d4fc70 100644
--- a/web/workspace/src/routes/hosting/setup/hosting-setup.browser.spec.ts
+++ b/web/workspace/src/routes/hosting/setup/hosting-setup.browser.spec.ts
@@ -34,6 +34,9 @@ function boundary(
     const path = String(input);
     if (path === "/api/auth/whoami") {
       return Response.json({
+        session: actor
+          ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+          : { kind: "anonymous" },
         actor: actor ? { ...authUser, auth_method: "browser_session" } : null,
       });
     }
@@ -121,7 +124,7 @@ test("enrollment clears token and omits cookies, then verifies an actual passkey
   expect(settings.getAttribute("href")).toBe("/hosting/settings");
   expect(get).toHaveBeenCalledTimes(1);
   expect(fetcher.mock.calls.filter(([path]) => path === "/api/auth/whoami"))
-    .toHaveLength(1);
+    .toHaveLength(2);
   expect(fetcher.mock.calls.filter(([path]) => path === "/api/hosting/access"))
     .toHaveLength(1);
   expect(
@@ -172,6 +175,7 @@ test("a different cookie actor cannot be accepted as the enrolled administrator"
   fetcher.mockImplementation(async (input, init) =>
     String(input) === "/api/auth/whoami"
       ? Response.json({
+        session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
         actor: {
           ...authUser,
           user_id: "other-user",
@@ -248,7 +252,10 @@ test("API token identity is not mistaken for a verified browser session", async
   const original = fetcher.getMockImplementation()!;
   fetcher.mockImplementation(async (input, init) =>
     String(input) === "/api/auth/whoami"
-      ? Response.json({ actor: { ...authUser, auth_method: "api_token" } })
+      ? Response.json({
+        session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+        actor: { ...authUser, auth_method: "api_token" },
+      })
       : original(input, init)
   );
   render(Setup);
diff --git a/web/workspace/src/routes/sidebar-fold.browser.spec.ts b/web/workspace/src/routes/sidebar-fold.browser.spec.ts
index 77cd3c5c0..bf05c26e4 100644
--- a/web/workspace/src/routes/sidebar-fold.browser.spec.ts
+++ b/web/workspace/src/routes/sidebar-fold.browser.spec.ts
@@ -4,34 +4,62 @@ import { cleanup, fireEvent, render, screen } from "@testing-library/svelte";
 import { afterEach, beforeEach, expect, test, vi } from "vitest";
 import { createRawSnippet, tick } from "svelte";
 import { logout } from "#lib/workspace/auth/api.ts";
-import { clearWorkspaceAlerts, pushWorkspaceAlert } from '#lib/workspace/alerts/store.ts';
-import { page } from '$app/state';
-import { settle } from '#lib/workspace/navigation/deferred.ts';
+import {
+  clearWorkspaceAlerts,
+  pushWorkspaceAlert,
+} from "#lib/workspace/alerts/store.ts";
+import { page } from "$app/state";
+import { settle } from "#lib/workspace/navigation/deferred.ts";
+import { browserSession } from "#lib/workspace/auth/session-state.ts";
+import {
+  authUser,
+  whoamiPayload,
+} from "#lib/workspace/auth/api.test-fixtures.ts";
 import Layout from "./+layout.svelte";
 
-vi.mock("$app/state", () => ({ page: { url: new URL("https://example.test/w/example") } }));
+vi.mock(
+  "$app/state",
+  () => ({ page: { url: new URL("https://example.test/w/example") } }),
+);
 const storageKey = "yoi.sidebar.mode.v1";
 const legacyKey = "yoi.sidebar.folded.v1";
 const props = {
   params: {},
   children: createRawSnippet(() => ({ render: () => "<p>Page content</p>" })),
-  data: { deferredCatalog: settle({ accessibleWorkspaces: [], workspaceCatalogError: null }) },
+  data: {
+    deferredCatalog: settle({
+      accessibleWorkspaces: [],
+      workspaceCatalogError: null,
+    }),
+  },
 };
 const frame = () => screen.getByRole("complementary", { name: "Sidebar" });
 const folded = () => frame().classList.contains("folded");
-const hoverRegion = () => frame().querySelector<HTMLElement>(".sidebar-hover-region")!;
-const enter = () => fireEvent.pointerEnter(hoverRegion(), { pointerType: "mouse" });
-const leave = () => fireEvent.pointerLeave(hoverRegion(), { pointerType: "mouse" });
+const hoverRegion = () =>
+  frame().querySelector<HTMLElement>(".sidebar-hover-region")!;
+const enter = () =>
+  fireEvent.pointerEnter(hoverRegion(), { pointerType: "mouse" });
+const leave = () =>
+  fireEvent.pointerLeave(hoverRegion(), { pointerType: "mouse" });
 const delay = () => vi.advanceTimersByTimeAsync(200);
 
 beforeEach(() => {
   localStorage.clear();
   clearWorkspaceAlerts();
-  vi.stubGlobal('fetch', vi.fn(async (input) => {
-    if (String(input) === '/api/auth/whoami') return Response.json({ actor: null });
-    throw new Error(`Unexpected request ${input}`);
-  }));
-  page.url = new URL('https://example.test/w/example');
+  browserSession.snapshot = {
+    kind: "ready",
+    value: whoamiPayload({ ...authUser, auth_method: "browser_session" }),
+  } as typeof browserSession.snapshot;
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async (input) => {
+      if (String(input) === "/api/auth/whoami") {
+        return Response.json({ session: { kind: "anonymous" }, actor: null });
+      }
+      throw new Error(`Unexpected request ${input}`);
+    }),
+  );
+  page.url = new URL("https://example.test/w/example");
   vi.useFakeTimers();
 });
 afterEach(() => {
@@ -42,22 +70,36 @@ afterEach(() => {
   localStorage.clear();
 });
 
-test.each(['/', '/dashboard', '/login', '/register', '/account', '/hosting/settings'])(
-  'standalone %s never displays retained private Workspace notifications',
+test.each([
+  "/",
+  "/dashboard",
+  "/login",
+  "/register",
+  "/account",
+  "/hosting/settings",
+])(
+  "standalone %s never displays retained private Workspace notifications",
   (path) => {
-    pushWorkspaceAlert('error', 'Private Workspace Orion: worker deletion failed');
-    page.url = new URL(path, 'https://example.test');
+    pushWorkspaceAlert(
+      "error",
+      "Private Workspace Orion: worker deletion failed",
+    );
+    page.url = new URL(path, "https://example.test");
     render(Layout, { props });
-    expect(screen.getByText('Page content')).toBeTruthy();
-    expect(screen.queryByText('Private Workspace Orion: worker deletion failed')).toBeNull();
-    expect(screen.queryByRole('alert')).toBeNull();
+    expect(screen.getByText("Page content")).toBeTruthy();
+    expect(
+      screen.queryByText("Private Workspace Orion: worker deletion failed"),
+    ).toBeNull();
+    expect(screen.queryByRole("alert")).toBeNull();
   },
 );
 
-test('Workspace shell continues displaying Workspace action notifications', () => {
-  pushWorkspaceAlert('error', 'Worker deletion failed');
+test("Workspace shell continues displaying Workspace action notifications", () => {
+  pushWorkspaceAlert("error", "Worker deletion failed");
   render(Layout, { props });
-  expect(screen.getByRole('alert').textContent).toContain('Worker deletion failed');
+  expect(screen.getByRole("alert").textContent).toContain(
+    "Worker deletion failed",
+  );
 });
 
 test("Workspace catalog failure uses the shared alert without rendering diagnostics in the sidebar", async () => {
@@ -65,7 +107,10 @@ test("Workspace catalog failure uses the shared alert without rendering diagnost
     props: {
       ...props,
       data: {
-        deferredCatalog: settle({ accessibleWorkspaces: [], workspaceCatalogError: "Workspace catalog request failed" }),
+        deferredCatalog: settle({
+          accessibleWorkspaces: [],
+          workspaceCatalogError: "Workspace catalog request failed",
+        }),
       },
     },
   });
@@ -78,10 +123,16 @@ test("Workspace catalog failure uses the shared alert without rendering diagnost
 
 test("unpinning changes mode, and pointer departure closes the preview", async () => {
   render(Layout, { props });
-  expect(screen.getByRole("button", { name: "Unpin sidebar" }).getAttribute("aria-pressed")).toBe("true");
+  expect(
+    screen.getByRole("button", { name: "Unpin sidebar" }).getAttribute(
+      "aria-pressed",
+    ),
+  ).toBe("true");
   await enter();
   screen.getByRole("button", { name: "Unpin sidebar" }).focus();
-  await fireEvent.click(screen.getByRole("button", { name: "Unpin sidebar" }), { detail: 1 });
+  await fireEvent.click(screen.getByRole("button", { name: "Unpin sidebar" }), {
+    detail: 1,
+  });
   expect(localStorage.getItem(storageKey)).toBe("hover");
   expect(folded()).toBe(false);
   await leave();
@@ -107,7 +158,9 @@ test("footer pointer clicks release previous sidebar link focus before unpinning
   render(Layout, { props });
   frame().querySelector<HTMLAnchorElement>("a")!.focus();
   await tick();
-  await fireEvent.click(screen.getByRole("button", { name: "Unpin sidebar" }), { detail: 1 });
+  await fireEvent.click(screen.getByRole("button", { name: "Unpin sidebar" }), {
+    detail: 1,
+  });
   expect(folded()).toBe(true);
 });
 
@@ -121,12 +174,15 @@ test("keyboard mode switching preserves the focused preview", async () => {
   expect(folded()).toBe(false);
 });
 
-test.each(["pinned", "hover"])("restores %s mode without persisting a transient open state", (mode) => {
-  localStorage.setItem(storageKey, mode);
-  render(Layout, { props });
-  expect(folded()).toBe(mode === "hover");
-  expect(localStorage.getItem(storageKey)).toBe(mode);
-});
+test.each(["pinned", "hover"])(
+  "restores %s mode without persisting a transient open state",
+  (mode) => {
+    localStorage.setItem(storageKey, mode);
+    render(Layout, { props });
+    expect(folded()).toBe(mode === "hover");
+    expect(localStorage.getItem(storageKey)).toBe(mode);
+  },
+);
 
 test.each([true, false])("migrates legacy folded=%s to a mode", (value) => {
   localStorage.setItem(legacyKey, String(value));
@@ -171,7 +227,8 @@ test("footer hover does not open or hold the preview, but its button still chang
   render(Layout, { props });
   const footer = frame().querySelector<HTMLElement>(".sidebar-control-row")!;
   const button = screen.getByRole("button", { name: "Pin sidebar" });
-  expect(button.querySelector('[data-icon="panel-right-open"] rect')).not.toBeNull();
+  expect(button.querySelector('[data-icon="panel-right-open"] rect')).not
+    .toBeNull();
   await fireEvent.pointerEnter(footer, { pointerType: "mouse" });
   await fireEvent.pointerEnter(button, { pointerType: "mouse" });
   await delay();
@@ -184,7 +241,8 @@ test("footer hover does not open or hold the preview, but its button still chang
   expect(folded()).toBe(true);
   await fireEvent.click(button, { detail: 1 });
   expect(folded()).toBe(false);
-  expect(button.querySelector('[data-icon="panel-right-close"] rect')).not.toBeNull();
+  expect(button.querySelector('[data-icon="panel-right-close"] rect')).not
+    .toBeNull();
 });
 
 test("keyboard focus opens the preview and holds it until focus leaves", async () => {
@@ -206,7 +264,9 @@ test("pinning a preview keeps it open after pointer and focus leave", async () =
   localStorage.setItem(storageKey, "hover");
   render(Layout, { props });
   await enter();
-  await fireEvent.click(screen.getByRole("button", { name: "Pin sidebar" }), { detail: 1 });
+  await fireEvent.click(screen.getByRole("button", { name: "Pin sidebar" }), {
+    detail: 1,
+  });
   await leave();
   await delay();
   expect(folded()).toBe(false);
@@ -214,7 +274,10 @@ test("pinning a preview keeps it open after pointer and focus leave", async () =
 });
 
 test("mode survives logout and remount, but an open preview does not", async () => {
-  vi.stubGlobal("fetch", vi.fn(async () => Response.json({ status: "logged_out" })));
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async () => Response.json({ status: "logged_out" })),
+  );
   localStorage.setItem(storageKey, "hover");
   const view = render(Layout, { props });
   await enter();
@@ -229,7 +292,9 @@ test("touch does not hover; mobile header opens temporarily without changing mod
   const matchMedia = window.matchMedia.bind(window);
   vi.spyOn(window, "matchMedia").mockImplementation((query) => {
     const result = matchMedia(query);
-    Object.defineProperty(result, "matches", { value: query === "(max-width: 760px)" });
+    Object.defineProperty(result, "matches", {
+      value: query === "(max-width: 760px)",
+    });
     return result;
   });
   localStorage.setItem(storageKey, "hover");
@@ -255,7 +320,9 @@ test("invalid storage falls back to pinned", () => {
 });
 
 test("unavailable storage does not prevent mode switching", async () => {
-  vi.spyOn(window, "localStorage", "get").mockImplementation(() => { throw new DOMException("Blocked", "SecurityError"); });
+  vi.spyOn(window, "localStorage", "get").mockImplementation(() => {
+    throw new DOMException("Blocked", "SecurityError");
+  });
   render(Layout, { props });
   await fireEvent.click(screen.getByRole("button", { name: "Unpin sidebar" }));
   await delay();
@@ -266,7 +333,9 @@ test("unavailable storage does not prevent mode switching", async () => {
 
 test("full storage still restores the mode and allows changes", async () => {
   localStorage.setItem(storageKey, "hover");
-  vi.spyOn(Storage.prototype, "setItem").mockImplementation(() => { throw new DOMException("Full", "QuotaExceededError"); });
+  vi.spyOn(Storage.prototype, "setItem").mockImplementation(() => {
+    throw new DOMException("Full", "QuotaExceededError");
+  });
   render(Layout, { props });
   await fireEvent.click(screen.getByRole("button", { name: "Pin sidebar" }));
   expect(folded()).toBe(false);
diff --git a/web/workspace/src/routes/w/[workspaceId]/+layout.ts b/web/workspace/src/routes/w/[workspaceId]/+layout.ts
index 69e9eb9c1..c38d79816 100644
--- a/web/workspace/src/routes/w/[workspaceId]/+layout.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/+layout.ts
@@ -5,12 +5,18 @@ import { parseWorkspaceResponse } from "#lib/workspace/api/workspace-model.ts";
 import { settle } from "#lib/workspace/navigation/deferred.ts";
 import type { LayoutLoad } from "./$types";
 
-export const load = ({ fetch, params }: Parameters<LayoutLoad>[0]) => {
+export const load = async (
+  { fetch, params, parent }: Parameters<LayoutLoad>[0],
+) => {
+  await parent();
   const workspaceId = params.workspaceId;
   return { deferredWorkspace: settle(loadWorkspace(fetch, workspaceId)) };
 };
 
-async function loadWorkspace(fetch: Parameters<LayoutLoad>[0]["fetch"], workspaceId: string) {
+async function loadWorkspace(
+  fetch: Parameters<LayoutLoad>[0]["fetch"],
+  workspaceId: string,
+) {
   const [workspaceResult, repositoryResult] = await Promise.all([
     loadJson(
       fetch,
@@ -43,4 +49,4 @@ async function loadWorkspace(fetch: Parameters<LayoutLoad>[0]["fetch"], workspac
     repositories,
     repositoriesError,
   };
-};
+}
diff --git a/web/workspace/src/routes/w/[workspaceId]/+page.ts b/web/workspace/src/routes/w/[workspaceId]/+page.ts
index 8342859b9..399722330 100644
--- a/web/workspace/src/routes/w/[workspaceId]/+page.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/+page.ts
@@ -1,7 +1,8 @@
 import { loadDashboard } from "#lib/workspace/home/dashboard.ts";
 import type { PageLoad } from "./$types";
 
-export const load: PageLoad = ({ fetch, params, depends }) => {
+export const load: PageLoad = async ({ fetch, params, depends, parent }) => {
+  await parent();
   depends("workspace:home");
   return {
     workspaceId: params.workspaceId,
diff --git a/web/workspace/src/routes/w/[workspaceId]/home.browser.spec.ts b/web/workspace/src/routes/w/[workspaceId]/home.browser.spec.ts
index 63dd65ea8..6ef2a0e1e 100644
--- a/web/workspace/src/routes/w/[workspaceId]/home.browser.spec.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/home.browser.spec.ts
@@ -79,6 +79,7 @@ test("loader only uses bounded read-only supported endpoints and advertises expl
   const depends = vi.fn();
   const result = await load(
     {
+      parent: async () => ({}),
       fetch,
       params: { workspaceId: "home-owner" },
       depends,
diff --git a/web/workspace/src/routes/w/[workspaceId]/objectives/[objectiveId]/+page.ts b/web/workspace/src/routes/w/[workspaceId]/objectives/[objectiveId]/+page.ts
index b7bb02171..f9f7a8e62 100644
--- a/web/workspace/src/routes/w/[workspaceId]/objectives/[objectiveId]/+page.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/objectives/[objectiveId]/+page.ts
@@ -1,3 +1,4 @@
+import { browserUrlSuffix } from "#lib/workspace/auth/routes.ts";
 import { redirect } from "@sveltejs/kit";
 import { loadJson, workspaceApiPath } from "#lib/workspace/api/http.ts";
 import {
@@ -11,36 +12,39 @@ import {
 import type { PageLoad } from "./$types";
 import { deferPage } from "#lib/workspace/navigation/deferred.ts";
 
-export const load = deferPage(async ({ fetch, params }: Parameters<PageLoad>[0]) => {
-  const apiPath = (path: string) => workspaceApiPath(params.workspaceId, path);
-  const objectiveId = resourceKey(params.objectiveId);
-  const objective = await loadJson(
-    fetch,
-    apiPath(`/objectives/${encodeURIComponent(objectiveId)}`),
-    undefined,
-    parseObjectiveDetail,
-    TICKET_BROWSER_API_LOAD_POLICY,
-  );
-
-  if (objective.data) {
-    const canonical = canonicalResourceReference(
-      objective.data.resource_key,
-      objective.data.title,
+export const load = deferPage(
+  async ({ fetch, params, url }: Parameters<PageLoad>[0]) => {
+    const apiPath = (path: string) =>
+      workspaceApiPath(params.workspaceId, path);
+    const objectiveId = resourceKey(params.objectiveId);
+    const objective = await loadJson(
+      fetch,
+      apiPath(`/objectives/${encodeURIComponent(objectiveId)}`),
+      undefined,
+      parseObjectiveDetail,
+      TICKET_BROWSER_API_LOAD_POLICY,
     );
-    if (params.objectiveId !== canonical) {
-      redirect(
-        308,
-        `/w/${encodeURIComponent(params.workspaceId)}/objectives/${
-          encodeURIComponent(canonical)
-        }`,
-      );
-    }
-  }
 
-  return {
-    workspaceId: params.workspaceId,
-    objectiveId,
-    objective: objective.data,
-    objectiveError: objective.error,
-  };
-});
+    if (objective.data) {
+      const canonical = canonicalResourceReference(
+        objective.data.resource_key,
+        objective.data.title,
+      );
+      if (params.objectiveId !== canonical) {
+        redirect(
+          308,
+          `/w/${encodeURIComponent(params.workspaceId)}/objectives/${
+            encodeURIComponent(canonical)
+          }${browserUrlSuffix(url)}`,
+        );
+      }
+    }
+
+    return {
+      workspaceId: params.workspaceId,
+      objectiveId,
+      objective: objective.data,
+      objectiveError: objective.error,
+    };
+  },
+);
diff --git a/web/workspace/src/routes/w/[workspaceId]/tickets/[ticketId]/+page.ts b/web/workspace/src/routes/w/[workspaceId]/tickets/[ticketId]/+page.ts
index e0f8f2bd2..bedfcaa93 100644
--- a/web/workspace/src/routes/w/[workspaceId]/tickets/[ticketId]/+page.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/tickets/[ticketId]/+page.ts
@@ -1,3 +1,4 @@
+import { browserUrlSuffix } from "#lib/workspace/auth/routes.ts";
 import { error, redirect } from "@sveltejs/kit";
 import { loadJson, workspaceApiPath } from "#lib/workspace/api/http.ts";
 import { loadWorkspaceRepositoryList } from "#lib/workspace/api/repositories.ts";
@@ -14,57 +15,62 @@ import type { WorkspaceOrchestratorStatus } from "#lib/workspace/tickets/ticket-
 import type { PageLoad } from "./$types";
 import { deferPage } from "#lib/workspace/navigation/deferred.ts";
 
-export const load = deferPage(async ({ fetch, params }: Parameters<PageLoad>[0]) => {
-  const reference = resourceKey(params.ticketId);
-  const ticketPath = workspaceApiPath(
-    params.workspaceId,
-    `/tickets/${encodeURIComponent(reference)}`,
-  );
-  const [ticket, repositoriesRaw, orchestrator] = await Promise.all([
-    loadJson(
-      fetch,
-      ticketPath,
-      undefined,
-      parseTicketDetail,
-      TICKET_BROWSER_API_LOAD_POLICY,
-    ),
-    loadWorkspaceRepositoryList(fetch, params.workspaceId),
-    loadJson<WorkspaceOrchestratorStatus>(
-      fetch,
-      workspaceApiPath(params.workspaceId, "/orchestrator"),
-      undefined,
-      parseBrowserWorkspaceOrchestratorResponse,
-    ),
-  ]);
-  if (!ticket.data) {
-    const message = ticket.error ?? "Ticket details could not be loaded";
-    if (ticket.status !== undefined && ticket.status >= 400 && ticket.status <= 599) {
-      error(ticket.status, message);
-    }
-    // Expected read failures belong to the deferred loader, not component construction.
-    throw new Error(message);
-  }
-  if (ticket.data) {
-    const canonical = canonicalResourceReference(
-      ticket.data.resource_key,
-      ticket.data.title,
+export const load = deferPage(
+  async ({ fetch, params, url }: Parameters<PageLoad>[0]) => {
+    const reference = resourceKey(params.ticketId);
+    const ticketPath = workspaceApiPath(
+      params.workspaceId,
+      `/tickets/${encodeURIComponent(reference)}`,
     );
-    if (params.ticketId !== canonical) {
-      redirect(
-        308,
-        `/w/${encodeURIComponent(params.workspaceId)}/tickets/${
-          encodeURIComponent(canonical)
-        }`,
-      );
+    const [ticket, repositoriesRaw, orchestrator] = await Promise.all([
+      loadJson(
+        fetch,
+        ticketPath,
+        undefined,
+        parseTicketDetail,
+        TICKET_BROWSER_API_LOAD_POLICY,
+      ),
+      loadWorkspaceRepositoryList(fetch, params.workspaceId),
+      loadJson<WorkspaceOrchestratorStatus>(
+        fetch,
+        workspaceApiPath(params.workspaceId, "/orchestrator"),
+        undefined,
+        parseBrowserWorkspaceOrchestratorResponse,
+      ),
+    ]);
+    if (!ticket.data) {
+      const message = ticket.error ?? "Ticket details could not be loaded";
+      if (
+        ticket.status !== undefined && ticket.status >= 400 &&
+        ticket.status <= 599
+      ) {
+        error(ticket.status, message);
+      }
+      // Expected read failures belong to the deferred loader, not component construction.
+      throw new Error(message);
     }
-  }
-  const repositories = repositoriesRaw;
+    if (ticket.data) {
+      const canonical = canonicalResourceReference(
+        ticket.data.resource_key,
+        ticket.data.title,
+      );
+      if (params.ticketId !== canonical) {
+        redirect(
+          308,
+          `/w/${encodeURIComponent(params.workspaceId)}/tickets/${
+            encodeURIComponent(canonical)
+          }${browserUrlSuffix(url)}`,
+        );
+      }
+    }
+    const repositories = repositoriesRaw;
 
-  return {
-    workspaceId: params.workspaceId,
-    ticketId: ticket.data?.id ?? reference,
-    ticket,
-    repositories,
-    orchestrator,
-  };
-});
+    return {
+      workspaceId: params.workspaceId,
+      ticketId: ticket.data?.id ?? reference,
+      ticket,
+      repositories,
+      orchestrator,
+    };
+  },
+);
diff --git a/web/workspace/src/routes/w/[workspaceId]/tickets/ticket-list.browser.spec.ts b/web/workspace/src/routes/w/[workspaceId]/tickets/ticket-list.browser.spec.ts
index 9db434f5c..50690553f 100644
--- a/web/workspace/src/routes/w/[workspaceId]/tickets/ticket-list.browser.spec.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/tickets/ticket-list.browser.spec.ts
@@ -108,6 +108,7 @@ async function loadPage(
 ) {
   const result = await load(
     {
+      parent: async () => ({}),
       fetch: fetchFn,
       params: { workspaceId },
       url: new URL(
@@ -141,7 +142,7 @@ test("actual loader posts browse only; rows render while orchestrator is unresol
     "/api/w/workspace-a/repositories": () => repos.promise,
   });
   const pending = loadPage(request);
-  expect(request).toHaveBeenCalledTimes(1);
+  await waitFor(() => expect(request).toHaveBeenCalledTimes(1));
   expect(request.mock.calls[0][0]).toBe("/api/w/workspace-a/tickets/browse");
   expect(request.mock.calls[0][1]?.method).toBe("POST");
   expect(JSON.parse(String(request.mock.calls[0][1]?.body))).toEqual(
diff --git a/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/+page.ts b/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/+page.ts
index 9e28f6848..306c9a894 100644
--- a/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/+page.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/+page.ts
@@ -1,3 +1,4 @@
+import { browserUrlSuffix } from "#lib/workspace/auth/routes.ts";
 import { redirect } from "@sveltejs/kit";
 import { loadJson, workspaceApiPath } from "#lib/workspace/api/http.ts";
 import { parseWorkerSummary } from "#lib/workspace/api/workers.ts";
@@ -8,33 +9,37 @@ import {
 import type { PageLoad } from "./$types";
 import { deferPage } from "#lib/workspace/navigation/deferred.ts";
 
-export const load = deferPage(async ({ fetch, params }: Parameters<PageLoad>[0]) => {
-  const reference = resourceKey(params.workerRef);
-  const result = await loadJson(
-    fetch,
-    workspaceApiPath(
-      params.workspaceId,
-      `/workers/${encodeURIComponent(reference)}`,
-    ),
-    undefined,
-    parseWorkerSummary,
-    { diagnosticLabel: "Worker API", maxResponseBytes: 8 * 1024 * 1024 },
-  );
-  if (result.data?.resource_key) {
-    const canonical = canonicalResourceReference(
-      result.data.resource_key,
-      result.data.display_name,
+export const load = deferPage(
+  async ({ fetch, params, url }: Parameters<PageLoad>[0]) => {
+    const reference = resourceKey(params.workerRef);
+    const result = await loadJson(
+      fetch,
+      workspaceApiPath(
+        params.workspaceId,
+        `/workers/${encodeURIComponent(reference)}`,
+      ),
+      undefined,
+      parseWorkerSummary,
+      { diagnosticLabel: "Worker API", maxResponseBytes: 8 * 1024 * 1024 },
     );
-    if (params.workerRef !== canonical) {
-      redirect(
-        308,
-        `/w/${encodeURIComponent(params.workspaceId)}/workers/${encodeURIComponent(canonical)}`,
+    if (result.data?.resource_key) {
+      const canonical = canonicalResourceReference(
+        result.data.resource_key,
+        result.data.display_name,
       );
+      if (params.workerRef !== canonical) {
+        redirect(
+          308,
+          `/w/${encodeURIComponent(params.workspaceId)}/workers/${
+            encodeURIComponent(canonical)
+          }${browserUrlSuffix(url)}`,
+        );
+      }
     }
-  }
-  return {
-    workspaceId: params.workspaceId,
-    worker: result.data,
-    workerError: result.error,
-  };
-});
+    return {
+      workspaceId: params.workspaceId,
+      worker: result.data,
+      workerError: result.error,
+    };
+  },
+);
diff --git a/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/+page.ts b/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/+page.ts
index 8c5158aaf..a40941ff0 100644
--- a/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/+page.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/+page.ts
@@ -1,3 +1,4 @@
+import { browserUrlSuffix } from "#lib/workspace/auth/routes.ts";
 import { redirect } from "@sveltejs/kit";
 import { loadJson, workspaceApiPath } from "#lib/workspace/api/http.ts";
 import { parseWorkerSummary } from "#lib/workspace/api/workers.ts";
@@ -8,38 +9,40 @@ import {
 import { deferPage } from "#lib/workspace/navigation/deferred.ts";
 import type { PageLoad } from "./$types";
 
-export const load = deferPage(async ({ fetch, params }: Parameters<PageLoad>[0]) => {
-  const reference = resourceKey(params.workerRef);
-  const result = await loadJson(
-    fetch,
-    workspaceApiPath(
-      params.workspaceId,
-      `/workers/${encodeURIComponent(reference)}`,
-    ),
-    undefined,
-    parseWorkerSummary,
-    { diagnosticLabel: "Worker API", maxResponseBytes: 8 * 1024 * 1024 },
-  );
-  if (result.data?.resource_key) {
-    const canonical = canonicalResourceReference(
-      result.data.resource_key,
-      result.data.display_name,
+export const load = deferPage(
+  async ({ fetch, params, url }: Parameters<PageLoad>[0]) => {
+    const reference = resourceKey(params.workerRef);
+    const result = await loadJson(
+      fetch,
+      workspaceApiPath(
+        params.workspaceId,
+        `/workers/${encodeURIComponent(reference)}`,
+      ),
+      undefined,
+      parseWorkerSummary,
+      { diagnosticLabel: "Worker API", maxResponseBytes: 8 * 1024 * 1024 },
     );
-    if (params.workerRef !== canonical) {
-      redirect(
-        308,
-        `/w/${encodeURIComponent(params.workspaceId)}/workers/${
-          encodeURIComponent(canonical)
-        }/console`,
+    if (result.data?.resource_key) {
+      const canonical = canonicalResourceReference(
+        result.data.resource_key,
+        result.data.display_name,
       );
+      if (params.workerRef !== canonical) {
+        redirect(
+          308,
+          `/w/${encodeURIComponent(params.workspaceId)}/workers/${
+            encodeURIComponent(canonical)
+          }/console${browserUrlSuffix(url)}`,
+        );
+      }
     }
-  }
 
-  return {
-    workspaceId: params.workspaceId,
-    runtimeId: result.data?.runtime_id ?? null,
-    workerId: result.data?.worker_id ?? null,
-    worker: result.data,
-    workerError: result.error,
-  };
-});
+    return {
+      workspaceId: params.workspaceId,
+      runtimeId: result.data?.runtime_id ?? null,
+      workerId: result.data?.worker_id ?? null,
+      worker: result.data,
+      workerError: result.error,
+    };
+  },
+);
diff --git a/web/workspace/src/routes/w/[workspaceId]/workspace-error.browser.spec.ts b/web/workspace/src/routes/w/[workspaceId]/workspace-error.browser.spec.ts
index 272a06a35..2219a6431 100644
--- a/web/workspace/src/routes/w/[workspaceId]/workspace-error.browser.spec.ts
+++ b/web/workspace/src/routes/w/[workspaceId]/workspace-error.browser.spec.ts
@@ -5,17 +5,29 @@ import WorkspaceError from "./+error.svelte";
 import { load } from "./+layout.ts";
 
 const state = vi.hoisted(() => ({
-  page: { params: { workspaceId: "workspace-a" }, status: 500, error: { message: "Ticket Browser API response is invalid" } },
+  page: {
+    params: { workspaceId: "workspace-a" },
+    status: 500,
+    error: { message: "Ticket Browser API response is invalid" },
+  },
 }));
 vi.mock("$app/state", () => state);
-afterEach(() => { cleanup(); vi.restoreAllMocks(); });
+afterEach(() => {
+  cleanup();
+  vi.restoreAllMocks();
+});
 
 test("a child page error preserves its message and never claims Workspace deletion", async () => {
-  const reload = vi.spyOn(window.location, "reload").mockImplementation(() => {});
+  const reload = vi.spyOn(window.location, "reload").mockImplementation(
+    () => {},
+  );
   const view = render(WorkspaceError);
-  expect(view.getByRole("alert").textContent).toBe("Ticket Browser API response is invalid");
+  expect(view.getByRole("alert").textContent).toBe(
+    "Ticket Browser API response is invalid",
+  );
   expect(view.getByText("Error 500")).toBeTruthy();
-  expect(view.queryByText("The selected Workspace cannot be opened")).toBeNull();
+  expect(view.queryByText("The selected Workspace cannot be opened"))
+    .toBeNull();
   expect(view.queryByText("Workspace unavailable")).toBeNull();
   expect(view.queryByText("Create Workspace")).toBeNull();
   expect(view.queryByText("Choose another Workspace")).toBeNull();
@@ -28,31 +40,49 @@ async function loadFailure(workspaceFetch: () => Promise<Response>) {
     if (String(input).endsWith("/workspace")) return await workspaceFetch();
     return new Response("repository lookup unavailable", { status: 503 });
   });
-  return await load({ fetch: fetcher, params: { workspaceId: "workspace-a" } } as unknown as Parameters<typeof load>[0]).deferredWorkspace;
+  return await (await load(
+    {
+      fetch: fetcher,
+      parent: async () => ({}),
+      params: { workspaceId: "workspace-a" },
+    } as unknown as Parameters<typeof load>[0],
+  )).deferredWorkspace;
 }
 
-test.each([401, 403, 404, 500, 503])("Workspace HTTP %i is not rewritten as 404", async (status) => {
-  const result = await loadFailure(async () => new Response("private backend body", { status }));
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("expected a failed Workspace load");
-  expect(result.failure.status).toBe(status);
-  expect(result.failure.message).toBe(`Workspace API request failed with HTTP ${status}`);
-  expect(result.failure.message).not.toContain("private backend body");
-});
+test.each([401, 403, 404, 500, 503])(
+  "Workspace HTTP %i is not rewritten as 404",
+  async (status) => {
+    const result = await loadFailure(async () =>
+      new Response("private backend body", { status })
+    );
+    expect(result.ok).toBe(false);
+    if (result.ok) throw new Error("expected a failed Workspace load");
+    expect(result.failure.status).toBe(status);
+    expect(result.failure.message).toBe(
+      `Workspace API request failed with HTTP ${status}`,
+    );
+    expect(result.failure.message).not.toContain("private backend body");
+  },
+);
 
-test.each(["network", "json", "contract"] as const)("Workspace %s failures do not imply a missing Workspace", async (kind) => {
-  const result = await loadFailure(async () => {
-    if (kind === "network") throw new TypeError("Failed to fetch");
-    return kind === "json" ? new Response("not json") : Response.json({});
-  });
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("expected a failed Workspace load");
-  expect(result.failure.status).toBeNull();
-  expect(result.failure.message).toBe({
-    network: "Workspace API request could not be completed",
-    json: "Workspace API response could not be decoded as JSON",
-    contract: "Workspace API response is invalid",
-  }[kind]);
-  expect(result.failure.message).not.toContain("removed");
-  expect(result.failure.message).not.toContain("404");
-});
+test.each(["network", "json", "contract"] as const)(
+  "Workspace %s failures do not imply a missing Workspace",
+  async (kind) => {
+    const result = await loadFailure(async () => {
+      if (kind === "network") throw new TypeError("Failed to fetch");
+      return kind === "json" ? new Response("not json") : Response.json({});
+    });
+    expect(result.ok).toBe(false);
+    if (result.ok) throw new Error("expected a failed Workspace load");
+    expect(result.failure.status).toBeNull();
+    expect(result.failure.message).toBe(
+      {
+        network: "Workspace API request could not be completed",
+        json: "Workspace API response could not be decoded as JSON",
+        contract: "Workspace API response is invalid",
+      }[kind],
+    );
+    expect(result.failure.message).not.toContain("removed");
+    expect(result.failure.message).not.toContain("404");
+  },
+);
diff --git a/web/workspace/test/activation-browser/activation-shell.browser.test.ts b/web/workspace/test/activation-browser/activation-shell.browser.test.ts
index d3c464423..f1f027e81 100644
--- a/web/workspace/test/activation-browser/activation-shell.browser.test.ts
+++ b/web/workspace/test/activation-browser/activation-shell.browser.test.ts
@@ -143,11 +143,13 @@ Deno.test("activation standalone shell supports issuance, reissue, denial, resta
               path.startsWith("POST ")
             ).length;
             await go("/hosting/accounts", mode);
-            await page.getByText(
-              mode === "anonymous"
-                ? "Sign in with a hosting administrator account to issue activation codes."
-                : "Hosting administrator access is required.",
-            ).waitFor();
+            if (mode === "anonymous") {
+              await page.waitForURL("http://127.0.0.1:15381/");
+              await page.getByRole("heading", { name: "Yoi", exact: true })
+                .waitFor();
+            } else {await page.getByText(
+                "Hosting administrator access is required.",
+              ).waitFor();}
             assertEquals(
               await page.getByLabel("Account ID (handle)").count(),
               0,
diff --git a/web/workspace/test/activation-browser/fixture-server.ts b/web/workspace/test/activation-browser/fixture-server.ts
index 5abfa28e8..b448f4183 100644
--- a/web/workspace/test/activation-browser/fixture-server.ts
+++ b/web/workspace/test/activation-browser/fixture-server.ts
@@ -41,6 +41,9 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   if (path === "/api/workspaces") return new Response(null, { status: 503 });
   if (path === "/api/auth/whoami") {
     return Response.json({
+      session: mode !== "anonymous"
+        ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+        : { kind: "anonymous" },
       actor: mode === "anonymous"
         ? null
         : { ...user, auth_method: "browser_session" },
diff --git a/web/workspace/test/auth-browser/auth-shell.browser.test.ts b/web/workspace/test/auth-browser/auth-shell.browser.test.ts
index d02ab77be..bdbe8d5db 100644
--- a/web/workspace/test/auth-browser/auth-shell.browser.test.ts
+++ b/web/workspace/test/auth-browser/auth-shell.browser.test.ts
@@ -3,6 +3,7 @@
 import { assert, assertEquals } from "@std/assert";
 import { resolve } from "@std/path";
 import { type Browser, chromium, type Page } from "playwright";
+import { sessionNavigation } from "./session-navigation.ts";
 import {
   startOwnedProcesses,
   stopOwnedProcesses,
@@ -14,7 +15,7 @@ type Mutation = { path: string; keys: string[] };
 type Harness = {
   page: Page;
   mutations: Mutation[];
-  go: (path: string, mode?: string) => Promise<void>;
+  go: (path: string, mode?: string, unavailableRoot?: boolean) => Promise<void>;
 };
 const login = async (page: Page) => {
   await page.getByRole("button", { name: "Log in with passkey", exact: true })
@@ -67,6 +68,19 @@ async function isolated(
     const page = await context.newPage();
     const mutations: Mutation[] = [];
     const errors: string[] = [];
+    const rejectedLoads: unknown[] = [];
+    let expectsUnavailableRoot = false;
+    await page.exposeFunction(
+      "__authFixtureRejectedLoad",
+      (reason: unknown) => rejectedLoads.push(reason),
+    );
+    await page.addInitScript(() => {
+      window.addEventListener("unhandledrejection", (event) => {
+        void (window as unknown as {
+          __authFixtureRejectedLoad: (reason: unknown) => Promise<void>;
+        }).__authFixtureRejectedLoad(event.reason);
+      });
+    });
     page.on("pageerror", (error) => errors.push(error.message));
     page.on("request", (request) => {
       const path = new URL(request.url()).pathname;
@@ -81,14 +95,38 @@ async function isolated(
     await body({
       page,
       mutations,
-      go: async (path, mode = "anonymous") => {
-        const url = new URL(path, origin);
-        url.searchParams.set("fixture", mode);
-        await page.goto(url.href);
+      go: async (path, mode = "anonymous", unavailableRoot = false) => {
+        // fixture選択を実際の戻り先queryへ混入させない。同じcontextのcookieをHTTPで設定する。
+        expectsUnavailableRoot ||= unavailableRoot ||
+          (path.startsWith("/account") &&
+            [
+              "session-error",
+              "session-malformed",
+              "session-retry",
+              "network-error",
+            ].includes(mode));
+        const setup = new URL("/", origin);
+        setup.searchParams.set("fixture", mode);
+        await page.request.get(setup.href);
+        await page.goto(new URL(path, origin).href);
       },
     });
     await noOverflow(page);
-    assertEquals(errors, []);
+    // root load自身の503ではKitのstatic fallback再実行も同じHttpErrorをrejectする。
+    // minifyされたclass名で除外せず、意図した障害fixtureのstatus/bodyと件数だけを許す。
+    if (expectsUnavailableRoot && rejectedLoads.length > 0) {
+      for (const reason of rejectedLoads) {
+        assertEquals(reason, {
+          status: 503,
+          body: {
+            status: 503,
+            message:
+              "Your session could not be loaded. Login status is unknown. Retry this page.",
+          },
+        });
+      }
+      assertEquals(errors.length, rejectedLoads.length);
+    } else assertEquals(errors, []);
   } finally {
     await context.close();
   }
@@ -113,12 +151,13 @@ Deno.test("standalone auth separates login, registration, own account and explic
       readyUrl: `${origin}/health`,
     }],
     `${root}/tools/web-ux/scenarios/anonymous-entry.json`,
-    `${root}/target/web-ux/auth-interactions/processes`,
+    `${root}/target/web-ux/t767-validation/auth-interactions/processes`,
     [],
   );
   let browser: Browser | undefined;
   try {
     browser = await chromium.launch();
+    await sessionNavigation(t, browser, isolated, origin);
     for (const theme of ["light", "dark"] as const) {
       for (const width of [1440, 768, 390]) {
         const step = (
@@ -130,11 +169,11 @@ Deno.test("standalone auth separates login, registration, own account and explic
             () => isolated(browser!, body, theme, width),
           );
         await step(
-          "anonymous account replaces history with login then returns to own account",
+          "expired account replaces history with login then returns to own account",
           async ({ page, go, mutations }) => {
             await page.goto(`${origin}/health`);
             const historyBefore = await page.evaluate(() => history.length);
-            await go("/account");
+            await go("/account", "session-expired");
             await at(page, "/login?returnTo=%2Faccount");
             assertEquals(
               await page.evaluate(() => history.length),
@@ -208,16 +247,12 @@ Deno.test("standalone auth separates login, registration, own account and explic
             );
             await page.getByRole("button", { name: "Log out", exact: true })
               .click();
-            await page.getByRole("button", {
-              name: "Log in with passkey",
-              exact: true,
-            }).waitFor();
-            assertEquals(new URL(page.url()).pathname, "/login");
+            await page.getByRole("heading", { name: "Yoi", exact: true })
+              .waitFor();
+            assertEquals(new URL(page.url()).pathname, "/");
             await page.reload();
-            await page.getByRole("button", {
-              name: "Log in with passkey",
-              exact: true,
-            }).waitFor();
+            await page.getByRole("heading", { name: "Yoi", exact: true })
+              .waitFor();
             assertEquals(count(mutations, "/api/auth/logout"), 1);
           },
         );
@@ -410,10 +445,15 @@ Deno.test("standalone auth separates login, registration, own account and explic
         () =>
           isolated(browser!, async ({ page, go, mutations }) => {
             await go(path, "session-error");
-            await page.getByRole("button", {
-              name: "Retry session",
-              exact: true,
-            }).waitFor();
+            if (path === "/account") {
+              // 初回protected loadの確認不能はroot loaderの503。画面内再確認とは分ける。
+              await page.getByText(/Login status is unknown/i).waitFor();
+            } else {
+              await page.getByRole("button", {
+                name: "Retry session",
+                exact: true,
+              }).waitFor();
+            }
             assertEquals(
               await page.getByRole("link", {
                 name: "Log in to continue",
@@ -627,6 +667,9 @@ Deno.test("standalone auth separates login, registration, own account and explic
           "/register?returnTo=%2Flogin",
           "/activate",
           "/login/../login",
+          "/%2f%2fexample.invalid",
+          "/account?filter=%252F%252Fexample.invalid",
+          "/account#%5Cexample.invalid",
         ]
       ) {
         await t.step(
@@ -713,7 +756,11 @@ Deno.test("standalone auth separates login, registration, own account and explic
               count(mutations, `/api/auth/passkeys/${purpose}/complete`),
               0,
             );
-            await page.getByRole("button", { name: label, exact: true })
+            await page.getByRole("button", {
+              name: label,
+              exact: true,
+              includeHidden: true,
+            })
               .evaluate((button) => {
                 button.dispatchEvent(
                   new MouseEvent("click", { bubbles: true }),
diff --git a/web/workspace/test/auth-browser/capture.ts b/web/workspace/test/auth-browser/capture.ts
index de03bbf5c..22307164d 100644
--- a/web/workspace/test/auth-browser/capture.ts
+++ b/web/workspace/test/auth-browser/capture.ts
@@ -10,6 +10,10 @@ import type {
 
 const root = resolve(import.meta.dirname!, "../../../..");
 const phase = Deno.args[0] ?? "after";
+const coverage = Deno.args[1] ?? "all";
+if (coverage !== "all" && coverage !== "session") {
+  throw new Error("Expected capture coverage: all or session");
+}
 if (!/^[a-zA-Z0-9_-]+$/.test(phase)) {
   throw new Error("Expected safe capture label");
 }
@@ -86,7 +90,39 @@ const routes: RouteScenario[] = [
   route(
     "account-redirect",
     "/account?fixture=anonymous",
-    'button:text-is("Log in with passkey")',
+    'h1:text-is("Yoi")',
+  ),
+  route(
+    "expired-account",
+    "/account?fixture=session-expired&tab=keys#passkeys",
+    '[role="status"]:has-text("Your browser session expired")',
+  ),
+  route(
+    "expired-login",
+    "/login?fixture=session-expired-cancel-once&returnTo=%2Faccount%3Ftab%3Dkeys%23passkeys",
+    '[role="status"]:has-text("Your browser session expired")',
+    [
+      {
+        id: "initial",
+        label: "Explicit expiry and login continuation, not anonymous entry",
+        fullPage: true,
+      },
+      {
+        id: "cancelled",
+        label: "Cancelled passkey keeps expiry context and retry destination",
+        fullPage: true,
+        interaction: login,
+        ready: ready('[role="alert"]:has-text("cancelled")'),
+      },
+      {
+        id: "returned",
+        label:
+          "Retry confirms authentication before returning to the requested account",
+        fullPage: true,
+        interaction: login,
+        ready: ready('button:text-is("Add passkey to alice")'),
+      },
+    ],
   ),
   route("register", "/register?fixture=anonymous", `${id}:enabled`, [
     {
@@ -129,10 +165,10 @@ const routes: RouteScenario[] = [
       },
       {
         id: "logout",
-        label: "Log out returns to login",
+        label: "Log out forgets expiry and returns to public home",
         fullPage: true,
         interaction: [click('button:text-is("Log out")')],
-        ready: ready('button:text-is("Log in with passkey")'),
+        ready: ready('h1:text-is("Yoi")'),
       },
     ],
   ),
@@ -184,7 +220,7 @@ const routes: RouteScenario[] = [
   route(
     "account-session-error",
     "/account?fixture=session-error",
-    'button:text-is("Retry session")',
+    "text=/Login status is unknown/",
   ),
   route(
     "register-session-error",
@@ -297,6 +333,14 @@ const routes: RouteScenario[] = [
     ],
   ),
 ];
+const sessionCaptureIds = new Set([
+  "login",
+  "account-redirect",
+  "expired-account",
+  "expired-login",
+  "session-error",
+  "account-session-error",
+]);
 await Deno.mkdir(`${root}/target/web-ux`, { recursive: true });
 for (const colorScheme of ["light", "dark"] as const) {
   for (const width of [1440, 768, 390]) {
@@ -314,7 +358,9 @@ for (const colorScheme of ["light", "dark"] as const) {
         auth: { kind: "anonymous" },
       }],
       viewports: [{ width, height: 900, label: `${width}` }],
-      routes,
+      routes: coverage === "session"
+        ? routes.filter((route) => sessionCaptureIds.has(route.id))
+        : routes,
       redact: {
         // 初期撮影後にもfillする。空の入力まで恒久的に隠すと次の操作が不能になる。
         // 合成codeはsubmit直後に破棄され、pendingのdisabled入力だけを隠す。
diff --git a/web/workspace/test/auth-browser/entry-shell.browser.test.ts b/web/workspace/test/auth-browser/entry-shell.browser.test.ts
index f4a662232..659ae56c0 100644
--- a/web/workspace/test/auth-browser/entry-shell.browser.test.ts
+++ b/web/workspace/test/auth-browser/entry-shell.browser.test.ts
@@ -48,7 +48,7 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
       },
     ],
     `${root}/tools/web-ux/scenarios/anonymous-entry.json`,
-    `${root}/target/web-ux/entry-browser/processes`,
+    `${root}/target/web-ux/t767-validation/entry-browser/processes`,
     [],
   );
   try {
@@ -230,16 +230,8 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
               ];
               await page.getByRole("button", { name: "Log out", exact: true })
                 .click();
-              await page.getByRole("button", { name: "Log in with passkey" })
-                .waitFor();
-              retainedCounts.push(
-                await page.locator(".workspace-alert").count(),
-              );
-              await page.getByRole("link", {
-                name: "Dashboard / Workspaces",
-                exact: true,
-              }).click();
               await ready(page, "Log in");
+              assertEquals(new URL(page.url()).pathname, "/");
               retainedCounts.push(
                 await page.locator(".workspace-alert").count(),
               );
@@ -253,8 +245,11 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
               await page.getByRole("link", { name: "Yoi home", exact: true })
                 .click();
               await ready(page, "Log in");
+              retainedCounts.push(
+                await page.locator(".workspace-alert").count(),
+              );
               const folder =
-                `${root}/target/web-ux/entry-browser/private-alerts-${colorScheme}-${width}`;
+                `${root}/target/web-ux/t767-validation/entry-browser/private-alerts-${colorScheme}-${width}`;
               await Deno.mkdir(folder, { recursive: true });
               const bytes = await page.screenshot({
                 path: folder + "/viewport.png",
@@ -281,7 +276,7 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
                 JSON.stringify(
                   {
                     scenario:
-                      "Workspace Stop notification → Account logout → dashboard/login → public home (SPA)",
+                      "Workspace Stop notification → Account logout → public home → login → public home (SPA)",
                     boundary:
                       "synthetic HTTP and Worker subscription; production UI/router/store",
                     path: new URL(page.url()).pathname,
@@ -590,13 +585,19 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
                       display_name: "Alice",
                       auth_method: "browser_session",
                     },
+                    session: {
+                      kind: "authenticated",
+                      expires_at: "2099-01-01T00:00:00Z",
+                    },
                   },
                 });
               });
               await page.evaluate(() =>
                 window.dispatchEvent(new Event("focus"))
               );
-              await page.getByText("Loading session…", { exact: true })
+              await page.getByRole("status").filter({
+                hasText: "Loading session…",
+              })
                 .waitFor();
               const completed = page.waitForResponse((response) =>
                 response.request().method() === "POST" &&
@@ -611,9 +612,10 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
                 )
               );
               assertEquals(new URL(page.url()).pathname, "/dashboard");
+              // 確認中のsubtreeは副作用の結果を保持したままhidden/inertになる。
               assertEquals(
-                await page.getByLabel("Workspace display name").count(),
-                0,
+                await page.getByLabel("Workspace display name").isVisible(),
+                false,
               );
               releaseSession();
               const link = page.getByRole("link", {
@@ -630,7 +632,7 @@ Deno.test("public entry isolates Workspace authority and authenticated dashboard
                 0,
               );
               const folder =
-                `${root}/target/web-ux/entry-browser/confirmed-${colorScheme}-${width}`;
+                `${root}/target/web-ux/t767-validation/entry-browser/confirmed-${colorScheme}-${width}`;
               await Deno.mkdir(folder, { recursive: true });
               const bytes = await page.screenshot({
                 path: folder + "/viewport.png",
diff --git a/web/workspace/test/auth-browser/fixture-server.ts b/web/workspace/test/auth-browser/fixture-server.ts
index 5b7a8c1e8..e156ef458 100644
--- a/web/workspace/test/auth-browser/fixture-server.ts
+++ b/web/workspace/test/auth-browser/fixture-server.ts
@@ -1,5 +1,6 @@
 // 本番build/client/shellだけを検証する合成HTTP/WebAuthn境界。
-// 実認証・署名・cookie安全性・policyの永続化は検証しない。本文/credentialは記録しない。
+// 実認証・署名・製品cookie設計・policyの永続化は検証しない。本文/credentialは記録しない。
+// cookie-sessionは実HTTPのMax-AgeをChromiumが失効させる境界だけを検証する。Backendの判定は合成。
 import { extname, join, resolve } from "@std/path";
 import { setupWebAuthnProjection } from "../hosting-browser/setup-projection.ts";
 
@@ -22,6 +23,9 @@ type State = {
   signedIn: boolean;
   whoamiCalls: number;
   selfRegistrationEnabled: boolean;
+  expired: boolean;
+  expiresAt: string | null;
+  cookieSession: boolean;
 };
 const sessions = new Map<string, State>();
 const mime: Record<string, string> = {
@@ -62,7 +66,10 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   const selected = url.searchParams.get("fixture");
   let id = request.headers.get("cookie")?.match(/auth-fixture=([\w-]+)/)?.[1];
   // routeごとに独立。クライアントgoto後も同じ合成sessionをwhoamiへ投影する。
-  if (selected || !id || !sessions.has(id)) {
+  if (
+    (selected && sessions.get(id ?? "")?.mode !== selected) || !id ||
+    !sessions.has(id)
+  ) {
     id = crypto.randomUUID();
     sessions.set(id, {
       mode: selected ?? "anonymous",
@@ -72,13 +79,54 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
         selected?.startsWith("addition-") === true,
       whoamiCalls: 0,
       selfRegistrationEnabled: selected !== "policy-disabled",
+      expired: selected?.startsWith("session-expired") === true,
+      expiresAt: null,
+      cookieSession: false,
     });
   }
   const state = sessions.get(id)!;
   const { mode } = state;
+  const sessionCookiePresent = request.headers.get("cookie")?.split(/;\s*/)
+    .includes("auth-fixture-session=active") === true;
+  if (state.cookieSession && !sessionCookiePresent) {
+    state.signedIn = false;
+    state.expired = true;
+  }
+  // 制御は同一browser contextの合成fixtureに限定。認証・cookieをJSで偽造しない。
+  if (path === "/__ui_fixture/session") {
+    if (request.method === "POST") {
+      const { operation } = await request.json();
+      if (operation === "arm-cookie") {
+        state.signedIn = true;
+        state.expired = false;
+        state.cookieSession = true;
+        state.expiresAt = new Date(Date.now() + 3000).toISOString();
+        return Response.json({ expires_at: state.expiresAt }, {
+          headers: {
+            "set-cookie":
+              "auth-fixture-session=active; Max-Age=3; Path=/; HttpOnly; SameSite=Strict",
+          },
+        });
+      }
+      if (operation === "expire" || operation === "anonymous") {
+        state.signedIn = false;
+        state.expired = operation === "expire";
+        state.cookieSession = false;
+        state.expiresAt = null;
+      } else return new Response(null, { status: 400 });
+    }
+    return Response.json({
+      session_cookie_present: sessionCookiePresent,
+      whoami_calls: state.whoamiCalls,
+      expired: state.expired,
+    });
+  }
   if (path === "/__ui_fixture/webauthn.js") {
     let extra = "";
-    if (mode.endsWith("-cancel")) {
+    if (mode.endsWith("-cancel-once")) {
+      extra =
+        `for (const method of ['get','create']) { const original=navigator.credentials[method].bind(navigator.credentials); let first=true; Object.defineProperty(navigator.credentials,method,{configurable:true,value:async(...args)=>{if(first){first=false;throw new DOMException('Passkey cancelled','NotAllowedError')}return original(...args)}}); }`;
+    } else if (mode.endsWith("-cancel")) {
       extra =
         `for (const method of ['get','create']) Object.defineProperty(navigator.credentials,method,{configurable:true,value:async()=>{throw new DOMException('Passkey cancelled','NotAllowedError')}});`;
     } else if (mode.endsWith("-unsupported")) {
@@ -116,6 +164,13 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
       actor: state.signedIn
         ? { ...user, auth_method: "browser_session" }
         : null,
+      session: state.signedIn
+        ? {
+          kind: "authenticated",
+          expires_at: state.expiresAt ??
+            new Date(Date.now() + 86_400_000).toISOString(),
+        }
+        : { kind: state.expired ? "expired" : "anonymous" },
     });
   }
   if (path === "/api/auth/registration-policy") {
@@ -160,7 +215,15 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   }
   if (path === "/api/auth/logout") {
     state.signedIn = false;
-    return Response.json({ status: "logged_out" });
+    state.expired = false;
+    state.cookieSession = false;
+    state.expiresAt = null;
+    return Response.json({ status: "logged_out" }, {
+      headers: {
+        "set-cookie":
+          "auth-fixture-session=; Max-Age=0; Path=/; HttpOnly; SameSite=Strict",
+      },
+    });
   }
   if (path === "/api/auth/device-login/approve") {
     if (!state.signedIn) return new Response(null, { status: 401 });
@@ -187,7 +250,7 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
       return new Response(null, { status: 503 });
     }
     if (mode === `${purpose}-expired` && stage === "complete") {
-      if (purpose === "addition") state.signedIn = false;
+      // challengeの401だけではbrowser sessionの失効を主張しない。
       return new Response(null, { status: 401 });
     }
     if (stage === "options") {
@@ -197,6 +260,9 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
       );
     }
     state.signedIn = true;
+    state.expired = false;
+    state.cookieSession = false;
+    state.expiresAt = null;
     return Response.json({ user });
   }
   if (path === "/api/auth/activation/options") {
@@ -204,6 +270,9 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   }
   if (path === "/api/auth/activation/complete") {
     state.signedIn = true;
+    state.expired = false;
+    state.cookieSession = false;
+    state.expiresAt = null;
     return Response.json({ user });
   }
   // Workspace画面の既存fixtureを再利用する。認証/登録/作成APIの代わりにはしない。
diff --git a/web/workspace/test/auth-browser/session-navigation.ts b/web/workspace/test/auth-browser/session-navigation.ts
new file mode 100644
index 000000000..dc6a125ed
--- /dev/null
+++ b/web/workspace/test/auth-browser/session-navigation.ts
@@ -0,0 +1,589 @@
+/// <reference lib="dom" />
+// auth-shellの本番build/HTTP/WebAuthn fixtureと隔離contextを再利用する。
+// Max-Ageは本物のHTTP cookieをbrowserが消すことを観測するが、whoami分類は合成。
+// 実Serverのsession/marker/revoke判定の証明ではない。
+import { assert, assertEquals } from "@std/assert";
+import type { Browser, Page } from "playwright";
+
+type Harness = {
+  page: Page;
+  mutations: { path: string; keys: string[] }[];
+  go: (path: string, mode?: string, unavailableRoot?: boolean) => Promise<void>;
+};
+type Isolated = (
+  browser: Browser,
+  body: (harness: Harness) => Promise<void>,
+) => Promise<void>;
+
+export async function sessionNavigation(
+  t: Deno.TestContext,
+  browser: Browser,
+  isolated: Isolated,
+  origin: string,
+) {
+  const step = (name: string, body: (harness: Harness) => Promise<void>) =>
+    t.step(name, () => isolated(browser, body));
+  const login = (page: Page) =>
+    page.getByRole("button", { name: "Log in with passkey", exact: true })
+      .click();
+  const at = (page: Page, target: string) =>
+    page.waitForURL((url) =>
+      url.origin === origin && url.pathname + url.search + url.hash === target
+    );
+  const loginTarget = (target: string) =>
+    `/login?${new URLSearchParams({ returnTo: target })}`;
+  const control = async (page: Page, operation: string) => {
+    const response = await page.request.post(`${origin}/__ui_fixture/session`, {
+      data: { operation },
+    });
+    assertEquals(response.status(), 200);
+    return response;
+  };
+  const focus = (page: Page) =>
+    page.evaluate(() => window.dispatchEvent(new Event("focus")));
+  const noPrivateRequests = (page: Page) => {
+    const paths: string[] = [];
+    page.on("request", (request) => {
+      const path = new URL(request.url()).pathname;
+      if (/^\/api\/(workspaces|w\/|hosting\/)/.test(path)) paths.push(path);
+    });
+    return paths;
+  };
+  for (
+    const target of [
+      "/w/team/tickets?filter=100%25#entry",
+      "/w/team/tickets/%e6%9c%aa?filter=100%25#part%25",
+    ]
+  ) {
+    await step(
+      `expiry retains encoded URL data ${target}`,
+      async ({ page, go }) => {
+        const privateRequests = noPrivateRequests(page);
+        await go(target, "session-expired");
+        await at(page, loginTarget(target));
+        await page.getByRole("button", {
+          name: "Log in with passkey",
+          exact: true,
+        }).waitFor();
+        await page.reload();
+        await at(page, loginTarget(target));
+        assertEquals(privateRequests, []);
+      },
+    );
+  }
+  await step(
+    "successful login retains percent query and fragment data",
+    async ({ page, go }) => {
+      const target = "/account?filter=100%25#part%25";
+      await go(target, "session-expired");
+      await at(page, loginTarget(target));
+      await login(page);
+      await at(page, target);
+      await page.getByRole("button", { name: "Log out", exact: true })
+        .waitFor();
+    },
+  );
+  const protectedRoutes = [
+    "/dashboard",
+    "/account",
+    "/hosting/settings",
+    "/w/private/tickets",
+  ];
+  for (const path of protectedRoutes) {
+    await step(
+      `fresh anonymous ${path} goes to public root before private loaders`,
+      async ({ page, go, mutations }) => {
+        const privateRequests = noPrivateRequests(page);
+        await go(`${path}?view=private#selected`);
+        await at(page, "/");
+        await page.getByRole("heading", { name: "Yoi", exact: true }).waitFor();
+        assertEquals(await page.locator(".app-shell").count(), 0);
+        assertEquals(privateRequests, []);
+        assertEquals(mutations, []);
+      },
+    );
+    await step(
+      `expired ${path} preserves pathname query and fragment before private loaders`,
+      async ({ page, go }) => {
+        const target = `${path}?filter=a%2Fb&view=thread#selected`;
+        const privateRequests = noPrivateRequests(page);
+        await go(target, "session-expired");
+        await at(page, loginTarget(target));
+        await page.getByRole("button", {
+          name: "Log in with passkey",
+          exact: true,
+        }).waitFor();
+        assertEquals(privateRequests, []);
+      },
+    );
+  }
+  for (
+    const [path, selector] of [
+      ["/", "h1"],
+      ["/login", "button[type=submit]"],
+      ["/register", "#registration-handle"],
+      ["/activate", "#activation-handle"],
+      ["/login/device?user_code=ABCD-EFGH", 'a[href^="/login?"]'],
+      ["/hosting/setup", "#host-setup-token"],
+    ]
+  ) {
+    await step(
+      `anonymous public entry ${path} does not redirect or load private data`,
+      async ({ page, go }) => {
+        const privateRequests = noPrivateRequests(page);
+        await go(path);
+        // 固有controlのrenderまで待ち、単なるdocument load成功で済ませない。
+        if (path === "/register") {
+          await page.getByLabel("Display name", { exact: true }).waitFor();
+        } else await page.locator(selector).first().waitFor();
+        await at(page, path);
+        assertEquals(privateRequests, []);
+      },
+    );
+  }
+  await step(
+    "expired login reload cancellation and retry keep the complete original URL",
+    async ({ page, go, mutations }) => {
+      const target = "/account?tab=keys&filter=a%2Fb#passkeys";
+      await go(target, "session-expired-cancel-once");
+      await at(page, loginTarget(target));
+      await page.reload();
+      await login(page);
+      await page.getByRole("alert").filter({ hasText: /cancelled|timed out/i })
+        .waitFor();
+      await at(page, loginTarget(target));
+      assertEquals(
+        mutations.filter((m) => m.path.endsWith("/login/complete")).length,
+        0,
+      );
+      await login(page);
+      await at(page, target);
+      await page.getByRole("button", {
+        name: "Add passkey to alice",
+        exact: true,
+      }).waitFor();
+      await page.reload();
+      await at(page, target);
+      await page.getByRole("button", {
+        name: "Add passkey to alice",
+        exact: true,
+      }).waitFor();
+    },
+  );
+  for (
+    const mode of [
+      "session-error",
+      "session-malformed",
+      "session-loading",
+      "network-error",
+    ]
+  ) {
+    await step(
+      `protected ${mode} stays unknown without redirect or private loaders`,
+      async ({ page, go }) => {
+        if (mode === "network-error") {
+          await page.route(
+            "**/api/auth/whoami",
+            (route) => route.abort("failed"),
+          );
+        }
+        const privateRequests = noPrivateRequests(page);
+        const target = "/account?tab=keys#passkeys";
+        await go(target, mode);
+        if (mode === "session-loading") {
+          // 実要求がpendingであることを観測する。loadingの文言はloaderと画面で異なる。
+          await page.waitForLoadState("domcontentloaded");
+          assertEquals(
+            await page.getByRole("button", {
+              name: "Add passkey to alice",
+              exact: true,
+            }).count(),
+            0,
+          );
+        } else await page.getByText(/Login status is unknown/i).waitFor();
+        await at(page, target);
+        assertEquals(privateRequests, []);
+      },
+    );
+  }
+  await step(
+    "protected unknown can reload and retry without losing query or fragment",
+    async ({ page, go }) => {
+      const target = "/account?tab=keys#passkeys";
+      let failed = true;
+      await page.route(
+        "**/api/auth/whoami",
+        (route) => failed ? route.fulfill({ status: 503 }) : route.continue(),
+      );
+      await go(target, "account", true);
+      await page.getByText(/Login status is unknown/i).waitFor();
+      await at(page, target);
+      failed = false;
+      await page.reload();
+      await page.getByRole("button", {
+        name: "Add passkey to alice",
+        exact: true,
+      }).waitFor();
+      await at(page, target);
+    },
+  );
+  for (const active of [false, true]) {
+    await step(
+      `real HTTP Max-Age cookie disappears and ${
+        active ? "active expiry" : "reload"
+      } returns through login`,
+      async ({ page, go }) => {
+        const target = "/account?tab=keys#after-cookie-expiry";
+        await go(target, "account");
+        await page.getByRole("button", {
+          name: "Add passkey to alice",
+          exact: true,
+        }).waitFor();
+        const armed = await control(page, "arm-cookie");
+        assert(armed.headers()["set-cookie"].includes("Max-Age=3"));
+        const cookie = (await page.context().cookies()).find((c) =>
+          c.name === "auth-fixture-session"
+        );
+        assert(cookie?.httpOnly);
+        assert(cookie.expires > Date.now() / 1000);
+        if (active) {
+          // whoamiのexpires_atを製品timerへ渡す。テスト側clockの前進やcookie削除はしない。
+          const refreshed = page.waitForResponse((r) =>
+            new URL(r.url()).pathname === "/api/auth/whoami"
+          );
+          await focus(page);
+          const wire = await (await refreshed).json();
+          assertEquals(wire.session.kind, "authenticated");
+          assertEquals(
+            wire.session.expires_at,
+            (await armed.json()).expires_at,
+          );
+        }
+        // 固定sleepではなくHTTP要求にcookieが付かなくなる事実で同期する。
+        await page.evaluate(async () => {
+          const deadline = performance.now() + 10_000;
+          do {
+            const observation = await (await fetch("/__ui_fixture/session", {
+              cache: "no-store",
+            })).json();
+            if (observation.session_cookie_present === false) return;
+            await new Promise((resolve) => setTimeout(resolve, 100));
+          } while (performance.now() < deadline);
+          throw new Error("Primary session cookie did not naturally expire");
+        });
+        assertEquals(
+          (await page.context().cookies()).some((c) =>
+            c.name === "auth-fixture-session"
+          ),
+          false,
+        );
+        // 長寿命の識別補助は残る。全消去とは異なる条件を作ったことも確認する。
+        assert(
+          (await page.context().cookies()).some((c) =>
+            c.name === "auth-fixture"
+          ),
+        );
+        if (!active) await page.reload();
+        await at(page, loginTarget(target));
+        await page.reload();
+        await login(page);
+        await at(page, target);
+        await page.getByRole("button", {
+          name: "Add passkey to alice",
+          exact: true,
+        }).waitFor();
+      },
+    );
+  }
+  await step(
+    "concurrent API 401 and repeated session checks cannot overwrite the original expired return URL",
+    async ({ page, go }) => {
+      const target = "/w/private/tickets?view=thread#concurrent-expiry";
+      let release!: () => void;
+      const held = new Promise<void>((resolve) => release = resolve);
+      const statuses: number[] = [];
+      // 本番Workspace loaderの並列requestを止める。window.fetchの呼出しだけで
+      // 製品API clientの401再照会を通したことにはしない。
+      await page.route("**/api/w/private/**", async (route) => {
+        await held;
+        statuses.push(401);
+        await route.fulfill({ status: 401 });
+      });
+      const requests = Promise.all([
+        page.waitForRequest((r) =>
+          new URL(r.url()).pathname === "/api/w/private/workspace"
+        ),
+        page.waitForRequest((r) =>
+          new URL(r.url()).pathname === "/api/w/private/repositories"
+        ),
+      ]);
+      try {
+        await go(target, "account");
+        await requests;
+        await control(page, "expire");
+        release();
+        // focus等の外部契機なしに、同時401がwhoami再照会へ接続すること。
+        await at(page, loginTarget(target));
+        assert(statuses.length >= 2);
+        for (let i = 0; i < 2; i++) {
+          const response = page.waitForResponse((r) =>
+            new URL(r.url()).pathname === "/api/auth/whoami"
+          );
+          await focus(page);
+          await (await response).finished();
+        }
+        await at(page, loginTarget(target));
+        await page.unroute("**/api/w/private/**");
+        await login(page);
+        await at(page, target);
+      } finally {
+        release();
+      }
+    },
+  );
+  await step(
+    "delayed pre-logout authenticated response cannot restore private UI or an old return URL",
+    async ({ page, go }) => {
+      await go("/account?tab=keys#stale", "account");
+      await page.getByRole("button", { name: "Log out", exact: true })
+        .waitFor();
+      let started!: () => void;
+      let failed!: (error: unknown) => void;
+      let release!: () => void;
+      const requested = new Promise<void>((resolve, reject) => {
+        started = resolve;
+        failed = reject;
+      });
+      const held = new Promise<void>((resolve) => release = resolve);
+      let first = true;
+      await page.route("**/api/auth/whoami", async (route) => {
+        if (!first) return route.continue();
+        first = false;
+        try {
+          const old = await route.fetch({ timeout: 5000 });
+          started();
+          await held;
+          await route.fulfill({
+            response: old,
+            headers: { ...old.headers(), "x-auth-fixture-held": "true" },
+          });
+        } catch (error) {
+          failed(error);
+        }
+      });
+      try {
+        const observed = page.waitForRequest((r) =>
+          new URL(r.url()).pathname === "/api/auth/whoami"
+        );
+        await focus(page);
+        await observed;
+        await requested;
+        // 他tabの本物の製品logoutでgeneration/storage eventも通す。
+        const other = await page.context().newPage();
+        try {
+          await other.goto(`${origin}/account`);
+          await other.getByRole("button", { name: "Log out", exact: true })
+            .click();
+          await at(other, "/");
+          const delivered = page.waitForResponse((r) =>
+            r.headers()["x-auth-fixture-held"] === "true"
+          );
+          release();
+          await (await delivered).finished();
+          // 古い応答を実際に製品へ届け、readSession/renderのtask境界まで進める。
+          await page.evaluate(() =>
+            new Promise<void>((resolve) =>
+              requestAnimationFrame(() =>
+                requestAnimationFrame(() => resolve())
+              )
+            )
+          );
+          await at(page, "/");
+          assertEquals(new URL(page.url()).searchParams.has("returnTo"), false);
+          assertEquals(
+            await page.getByRole("button", {
+              name: "Add passkey to alice",
+              exact: true,
+            }).count(),
+            0,
+          );
+          await page.goto(`${origin}/account`);
+          await at(page, "/");
+        } finally {
+          await other.close();
+        }
+      } finally {
+        release();
+      }
+    },
+  );
+  await step(
+    "challenge 401 leaves an authenticated account in place and permits retry",
+    async ({ page, go }) => {
+      const target = "/account?tab=keys#challenge";
+      await go(target, "addition-expired");
+      await page.getByRole("button", {
+        name: "Add passkey to alice",
+        exact: true,
+      }).click();
+      await page.getByRole("alert").waitFor();
+      await at(page, target);
+      assertEquals(
+        (await (await page.request.get(`${origin}/api/auth/whoami`)).json())
+          .session.kind,
+        "authenticated",
+      );
+      assertEquals(
+        await page.getByRole("button", {
+          name: "Add passkey to alice",
+          exact: true,
+        }).isEnabled(),
+        true,
+      );
+    },
+  );
+  await step(
+    "explicit logout and complete browser storage removal classify as anonymous, not expired",
+    async ({ page, go }) => {
+      await go("/account", "account");
+      await control(page, "arm-cookie");
+      await page.getByRole("button", { name: "Log out", exact: true }).click();
+      await at(page, "/");
+      const wire = await (await page.request.get(`${origin}/api/auth/whoami`))
+        .json();
+      assertEquals(wire, { actor: null, session: { kind: "anonymous" } });
+      await page.evaluate(() => {
+        localStorage.clear();
+        sessionStorage.clear();
+      });
+      await page.context().clearCookies();
+      await page.goto(`${origin}/account?tab=keys#cleared`);
+      await at(page, "/");
+      assertEquals(new URL(page.url()).searchParams.has("returnTo"), false);
+    },
+  );
+  for (const event of ["pageshow", "visibilitychange"] as const) {
+    await step(
+      `${event} rechecks active session and preserves expired return URL`,
+      async ({ page, go }) => {
+        const target = "/account?tab=keys#lifecycle";
+        await go(target, "account");
+        await page.getByRole("button", {
+          name: "Add passkey to alice",
+          exact: true,
+        }).waitFor();
+        await control(page, "expire");
+        await page.evaluate((event) => {
+          if (event === "visibilitychange") {
+            if (document.hidden) {
+              throw new Error("Expected a visible test page");
+            }
+            document.dispatchEvent(new Event(event));
+          } else window.dispatchEvent(new Event(event));
+        }, event);
+        await at(page, loginTarget(target));
+      },
+    );
+  }
+  await step(
+    "forget expired session clears returnTo and fragment before a later login",
+    async ({ page, go, mutations }) => {
+      await go("/account?tab=keys#forgotten", "session-expired");
+      await page.getByRole("button", {
+        name: "Forget this session",
+        exact: true,
+      }).click();
+      await at(page, "/login");
+      await page.getByRole("button", {
+        name: "Log in with passkey",
+        exact: true,
+      }).waitFor();
+      assertEquals(
+        (await (await page.request.get(`${origin}/api/auth/whoami`)).json())
+          .session.kind,
+        "anonymous",
+      );
+      assertEquals(
+        mutations.filter((m) => m.path === "/api/auth/logout").length,
+        1,
+      );
+      await login(page);
+      await at(page, "/dashboard");
+    },
+  );
+  await step(
+    "forget session is allowed on unknown login and never claims authenticated success",
+    async ({ page, go, mutations }) => {
+      await go(
+        "/login?returnTo=%2Faccount%3Ftab%3Dkeys%23forgotten#entry",
+        "session-error",
+      );
+      await page.getByText(/Login status is unknown/i).waitFor();
+      await page.getByRole("button", {
+        name: "Forget this session",
+        exact: true,
+      }).click();
+      await at(page, "/login");
+      await page.getByText(/Login status is unknown/i).waitFor();
+      assertEquals(
+        mutations.filter((m) => m.path === "/api/auth/logout").length,
+        1,
+      );
+      assertEquals(
+        await page.getByRole("link", { name: /^Continue to/ }).count(),
+        0,
+      );
+    },
+  );
+  await step(
+    "other-tab logout clears a pending expired login return URL",
+    async ({ page, go }) => {
+      const target = "/account?tab=keys#other-tab-logout";
+      await go(target, "session-expired");
+      await at(page, loginTarget(target));
+      const other = await page.context().newPage();
+      try {
+        await other.goto(`${origin}${loginTarget(target)}`);
+        await other.getByRole("button", {
+          name: "Forget this session",
+          exact: true,
+        }).click();
+        await at(other, "/login");
+        await at(page, "/login");
+        await login(page);
+        await at(page, "/dashboard");
+      } finally {
+        await other.close();
+      }
+    },
+  );
+  for (const status of [403, 404]) {
+    await step(
+      `post-login resource ${status} remains a resource failure, never a relogin loop`,
+      async ({ page, go }) => {
+        const target = "/dashboard?selected=missing#resource";
+        let whoamiCalls = 0;
+        page.on("request", (request) => {
+          if (new URL(request.url()).pathname === "/api/auth/whoami") {
+            whoamiCalls++;
+          }
+        });
+        await page.route(
+          "**/api/workspaces?*",
+          (route) => route.fulfill({ status }),
+        );
+        await go(target, "session-expired");
+        await at(page, loginTarget(target));
+        await login(page);
+        await at(page, target);
+        await page.getByText(/Workspaces could not be loaded/).waitFor();
+        const before = whoamiCalls;
+        await page.reload();
+        await page.getByText(/Workspaces could not be loaded/).waitFor();
+        await at(page, target);
+        // reloadごとの有限なreadで、403/404をexpiredへ変換してloopしない。
+        assert(whoamiCalls - before <= 4);
+      },
+    );
+  }
+}
diff --git a/web/workspace/test/hosting-browser/fixture-server.ts b/web/workspace/test/hosting-browser/fixture-server.ts
index 9127016fe..845556bd7 100644
--- a/web/workspace/test/hosting-browser/fixture-server.ts
+++ b/web/workspace/test/hosting-browser/fixture-server.ts
@@ -4,7 +4,9 @@
 import { extname, join, resolve } from "@std/path";
 import { setupProjectionResponse } from "./setup-projection.ts";
 const [port, build] = Deno.args;
-if (!port || !build) throw new Error("usage: fixture-server.ts <port> <build-root>");
+if (!port || !build) {
+  throw new Error("usage: fixture-server.ts <port> <build-root>");
+}
 const buildRoot = resolve(build);
 const mime: Record<string, string> = {
   ".html": "text/html",
@@ -23,9 +25,15 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   const url = new URL(request.url);
   if (url.pathname === "/health") return new Response("ok");
   const selected = url.searchParams.get("fixture");
-  if (url.pathname === "/hosting/setup" && selected?.startsWith("setup-")) setupMode = selected;
-  const mode = selected ?? request.headers.get("cookie")?.match(/ui-fixture=([\w-]+)/)?.[1] ??
-    (url.pathname.startsWith("/api/auth/passkeys/addition/") ? setupMode : null) ?? "admin-on";
+  if (url.pathname === "/hosting/setup" && selected?.startsWith("setup-")) {
+    setupMode = selected;
+  }
+  const mode = selected ??
+    request.headers.get("cookie")?.match(/ui-fixture=([\w-]+)/)?.[1] ??
+    (url.pathname.startsWith("/api/auth/passkeys/addition/")
+      ? setupMode
+      : null) ??
+    "admin-on";
   if (selected) policies.delete(mode);
   const setup = setupProjectionResponse(url.pathname, mode, selected !== null);
   if (setup) return setup;
@@ -33,6 +41,9 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   const ordinary = mode.startsWith("ordinary");
   if (url.pathname === "/api/auth/whoami") {
     return Response.json({
+      session: !anonymous
+        ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+        : { kind: "anonymous" },
       actor: anonymous ? null : {
         user_id: "fixture-user",
         account_id: "fixture-account",
@@ -46,7 +57,9 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   if (url.pathname === "/api/hosting/access") {
     return Response.json({ is_admin: !ordinary && !anonymous });
   }
-  const policy = () => ({ self_registration_enabled: policies.get(mode) ?? !mode.includes("off") });
+  const policy = () => ({
+    self_registration_enabled: policies.get(mode) ?? !mode.includes("off"),
+  });
   if (url.pathname === "/api/auth/registration-policy") {
     if (mode === "account-error") {
       return new Response("synthetic availability failure", { status: 503 });
@@ -56,12 +69,17 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
   }
   if (url.pathname === "/api/hosting/settings") {
     if (anonymous || ordinary) {
-      return new Response("synthetic denied", { status: anonymous ? 401 : 403 });
+      return new Response("synthetic denied", {
+        status: anonymous ? 401 : 403,
+      });
     }
     if (mode === "admin-load-error") {
       return new Response("synthetic settings failure", { status: 503 });
     }
-    if (mode === "admin-loading" || (mode === "admin-saving" && request.method === "PUT")) {
+    if (
+      mode === "admin-loading" ||
+      (mode === "admin-saving" && request.method === "PUT")
+    ) {
       return new Promise<Response>(() => {});
     }
     if (request.method === "PUT") {
@@ -80,13 +98,18 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
     return new Response("unexpected fixture API", { status: 404 });
   }
   const path = join(buildRoot, decodeURIComponent(url.pathname));
-  if (!path.startsWith(buildRoot + "/")) return new Response("invalid path", { status: 400 });
+  if (!path.startsWith(buildRoot + "/")) {
+    return new Response("invalid path", { status: 400 });
+  }
   let bytes: Uint8Array;
   let extension = extname(path);
   try {
     bytes = await Deno.readFile(path);
   } catch (error) {
-    if (!(error instanceof Deno.errors.NotFound) && !(error instanceof Deno.errors.IsADirectory)) {
+    if (
+      !(error instanceof Deno.errors.NotFound) &&
+      !(error instanceof Deno.errors.IsADirectory)
+    ) {
       throw error;
     }
     bytes = await Deno.readFile(join(buildRoot, "index.html"));
@@ -106,6 +129,11 @@ Deno.serve({ hostname: "127.0.0.1", port: Number(port) }, async (request) => {
     "content-type": mime[extension] ?? "application/octet-stream",
     "cache-control": "no-store",
   });
-  if (selected) headers.set("set-cookie", `ui-fixture=${selected}; Path=/; SameSite=Strict`);
+  if (selected) {
+    headers.set(
+      "set-cookie",
+      `ui-fixture=${selected}; Path=/; SameSite=Strict`,
+    );
+  }
   return new Response(bytes as Uint8Array<ArrayBuffer>, { headers });
 });
diff --git a/web/workspace/test/hosting-browser/hosting-shell.browser.test.ts b/web/workspace/test/hosting-browser/hosting-shell.browser.test.ts
index 273d52d3c..3f5111ddd 100644
--- a/web/workspace/test/hosting-browser/hosting-shell.browser.test.ts
+++ b/web/workspace/test/hosting-browser/hosting-shell.browser.test.ts
@@ -189,12 +189,14 @@ Deno.test("hosting UI keyboard navigation, policy editing, denial and unknown sa
             await page.goto(
               `http://127.0.0.1:15379/hosting/settings?fixture=${mode}`,
             );
-            await page.getByText(
-              mode === "ordinary"
-                ? "Hosting administrator access is required."
-                : "Sign in with a hosting administrator account to view these settings.",
-              { exact: true },
-            ).waitFor();
+            if (mode === "anonymous") {
+              await page.waitForURL("http://127.0.0.1:15379/");
+              await page.getByRole("heading", { name: "Yoi", exact: true })
+                .waitFor();
+            } else {await page.getByText(
+                "Hosting administrator access is required.",
+                { exact: true },
+              ).waitFor();}
             assertEquals(await edit.count(), 0);
             assertEquals(await checkbox.count(), 0);
             assertEquals(
@@ -285,16 +287,19 @@ Deno.test("hosting UI keyboard navigation, policy editing, denial and unknown sa
             await page.locator(ready).waitFor();
             await noOverflow(page);
           }
-          // Navigation may also cancel the shell's concurrent identity/access
-          // reads. Only an explicit browser cancellation of these reads is expected.
+          // 遷移でidentity/settingsの読み取りや遅延font取得がbrowserに取消されることはある。
+          // 通信失敗一般を許すのではなく、これらの明示的な取消だけを区別する。
           assert(
             failedRequests.every(({ url, error }) =>
-              error === "net::ERR_ABORTED" && [
+              error === "net::ERR_ABORTED" && ([
                 "/api/hosting/settings",
                 "/api/auth/registration-policy",
                 "/api/auth/whoami",
                 "/api/hosting/access",
-              ].some((path) => url.endsWith(path))
+              ].some((path) => url.endsWith(path)) ||
+                /^\/_app\/immutable\/assets\/[^/]+\.woff2$/.test(
+                  new URL(url).pathname,
+                ))
             ),
             JSON.stringify(failedRequests),
           );
diff --git a/web/workspace/test/hosting-browser/setup-projection.ts b/web/workspace/test/hosting-browser/setup-projection.ts
index 3f059c469..bb4b93222 100644
--- a/web/workspace/test/hosting-browser/setup-projection.ts
+++ b/web/workspace/test/hosting-browser/setup-projection.ts
@@ -29,7 +29,12 @@ export function setupProjectionResponse(
   }
   if (path === "/api/auth/whoami") {
     return Response.json({
-      actor: stages.get(mode) === "login" ? { ...user, auth_method: "browser_session" } : null,
+      session: stages.get(mode) === "login"
+        ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+        : { kind: "anonymous" },
+      actor: stages.get(mode) === "login"
+        ? { ...user, auth_method: "browser_session" }
+        : null,
     });
   }
   if (path === "/api/hosting/access") {
@@ -54,7 +59,10 @@ export function setupProjectionResponse(
     return Response.json({ user });
   }
   if (path === "/api/auth/passkeys/login/options") {
-    return Response.json({ challenge_id: "fixture-login", public_key: { challenge: "dWk" } });
+    return Response.json({
+      challenge_id: "fixture-login",
+      public_key: { challenge: "dWk" },
+    });
   }
   if (path === "/api/auth/passkeys/login/complete") {
     stages.set(mode, "login");
diff --git a/web/workspace/test/repository-access/loader.test.ts b/web/workspace/test/repository-access/loader.test.ts
index dd82f3cf7..f71881d9f 100644
--- a/web/workspace/test/repository-access/loader.test.ts
+++ b/web/workspace/test/repository-access/loader.test.ts
@@ -68,6 +68,7 @@ async function loadPageWithFailure(failedSuffix: string): Promise<LoadedPage> {
   };
   const envelope = loadRepositoryAccessPage(
     {
+      parent: async () => ({}),
       fetch: fetcher as typeof fetch,
       params: { workspaceId: "workspace-1" },
       url: new URL(
diff --git a/web/workspace/test/spa-shell.test.ts b/web/workspace/test/spa-shell.test.ts
index b75a9196e..fd4b56f38 100644
--- a/web/workspace/test/spa-shell.test.ts
+++ b/web/workspace/test/spa-shell.test.ts
@@ -1,4 +1,5 @@
 import { assertEquals } from "jsr:@std/assert";
+import { browserSession } from "../src/lib/workspace/auth/session-state.ts";
 import { load, ssr } from "../src/routes/+layout.ts";
 
 Deno.test("authentication and hosting shells never require Workspace catalog authority", async () => {
@@ -16,22 +17,88 @@ Deno.test("authentication and hosting shells never require Workspace catalog aut
       "/hosting/setup",
     ]
   ) {
+    const original = globalThis.fetch;
+    globalThis.fetch = async () =>
+      Response.json({
+        actor: {
+          user_id: "u",
+          account_id: "a",
+          handle: "alice",
+          display_name: "Alice",
+          auth_method: "browser_session",
+        },
+        session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+      });
+    browserSession.invalidate();
     let calls = 0;
     const event = {
+      depends: () => {},
       url: new URL(path, "https://workspace.test"),
       fetch: () => {
         calls++;
         throw new Error("Workspace API must not be called");
       },
     } as unknown as Parameters<typeof load>[0];
-    assertEquals(await load(event).deferredCatalog, {
+    assertEquals(await (await load(event)).deferredCatalog, {
       ok: true,
       data: { accessibleWorkspaces: [], workspaceCatalogError: null },
     });
     assertEquals(calls, 0);
+    browserSession.dispose();
+    globalThis.fetch = original;
   }
 });
 
 Deno.test("workspace frontend serves deep links through the client SPA", () => {
   assertEquals(ssr, false);
 });
+
+Deno.test("root admission never starts private catalog while anonymous, expired, loading or unknown", async () => {
+  const original = globalThis.fetch;
+  try {
+    for (
+      const condition of ["anonymous", "expired", "error", "loading"] as const
+    ) {
+      browserSession.invalidate();
+      let release!: () => void;
+      const pending = new Promise<void>((resolve) => {
+        release = resolve;
+      });
+      globalThis.fetch = async () => {
+        if (condition === "loading") await pending;
+        return condition === "error" || condition === "loading"
+          ? new Response(null, { status: 503 })
+          : Response.json({ actor: null, session: { kind: condition } });
+      };
+      let privateCalls = 0;
+      const event = {
+        url: new URL("https://workspace.test/w/team/tickets?q=mine#entry"),
+        depends: () => {},
+        fetch: () => {
+          ++privateCalls;
+          throw new Error("private fetch before admission");
+        },
+      } as unknown as Parameters<typeof load>[0];
+      const result = load(event).then(() => null, (rejection) => rejection);
+      await Promise.resolve();
+      assertEquals(privateCalls, 0);
+      release();
+      const rejected = await result;
+      assertEquals(
+        rejected.status,
+        condition === "anonymous" || condition === "expired" ? 307 : 503,
+      );
+      if (condition === "anonymous") assertEquals(rejected.location, "/");
+      if (condition === "expired") {
+        assertEquals(
+          rejected.location,
+          "/login?returnTo=%2Fw%2Fteam%2Ftickets%3Fq%3Dmine%23entry",
+        );
+      }
+      assertEquals(privateCalls, 0);
+    }
+  } finally {
+    browserSession.dispose();
+    globalThis.fetch = original;
+  }
+});
diff --git a/web/workspace/test/visual-review/account-passkeys-fixture-server.ts b/web/workspace/test/visual-review/account-passkeys-fixture-server.ts
index 6954fb19d..d5b292871 100644
--- a/web/workspace/test/visual-review/account-passkeys-fixture-server.ts
+++ b/web/workspace/test/visual-review/account-passkeys-fixture-server.ts
@@ -10,6 +10,10 @@ Deno.serve({ hostname: "127.0.0.1", port }, async (request) => {
   if (url.pathname === "/health") return new Response("ok");
   if (url.pathname === "/api/auth/whoami") {
     return Response.json({
+      session:
+        request.headers.get("cookie")?.includes("fixture-actor=authenticated")
+          ? { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" }
+          : { kind: "anonymous" },
       actor:
         request.headers.get("cookie")?.includes("fixture-actor=authenticated")
           ? {
diff --git a/web/workspace/test/visual-review/empty-workspace-fixture-server.ts b/web/workspace/test/visual-review/empty-workspace-fixture-server.ts
index b93695808..cc6c24511 100644
--- a/web/workspace/test/visual-review/empty-workspace-fixture-server.ts
+++ b/web/workspace/test/visual-review/empty-workspace-fixture-server.ts
@@ -11,8 +11,21 @@ import { dashboardFixture } from "../../src/lib/workspace/home/dashboard.test-fi
 
 Deno.serve({ hostname: "127.0.0.1", port }, async (request) => {
   const url = new URL(request.url);
-  if (url.pathname === "/api/auth/whoami") return Response.json({ actor: { user_id: "fixture-user", account_id: "fixture-owner", handle: "alice", display_name: "Alice", auth_method: "browser_session" } });
-  if (url.pathname === "/api/hosting/access") return Response.json({ is_admin: false });
+  if (url.pathname === "/api/auth/whoami") {
+    return Response.json({
+      session: { kind: "authenticated", expires_at: "2099-01-01T00:00:00Z" },
+      actor: {
+        user_id: "fixture-user",
+        account_id: "fixture-owner",
+        handle: "alice",
+        display_name: "Alice",
+        auth_method: "browser_session",
+      },
+    });
+  }
+  if (url.pathname === "/api/hosting/access") {
+    return Response.json({ is_admin: false });
+  }
   if (url.pathname === "/api/workspaces" && request.method === "POST") {
     return Response.json({
       message: