chore: merge develop into hare/develop

crates/protocol/src/lib.rs

@@ -340,8 +340,7 @@ pub struct InternalWorkerRef {
 pub struct InternalWorkerSnapshot {
     pub worker: InternalWorkerRef,
     pub revision: u64,
-    #[cfg_attr(feature = "typescript", ts(type = "Array<unknown>"))]
-    pub entries: Vec<serde_json::Value>,
+    pub session: SessionSnapshot,
     #[serde(default)]
     pub status: WorkerStatus,
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -364,12 +363,114 @@ pub enum ToolResultDisposition {
     OutcomeUnknown,
 }
 
+/// Canonical, storage-independent projection of committed session history.
+///
+/// Worker protocols expose this DTO instead of append-log records. New
+/// storage variants can therefore be added without teaching every client how
+/// to replay the durable log format.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+pub struct SessionSnapshot {
+    pub entries: Vec<SessionSnapshotEntry>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[serde(rename_all = "snake_case")]
+pub enum SessionEntryProvenance {
+    HumanInput,
+    WorkerInput,
+    FlowInstruction,
+    BackendInstruction,
+    ModelOutput,
+    ToolOutput,
+    DerivedSummary,
+    LegacyUnknown,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+pub struct SessionSnapshotEntry {
+    /// Stable identity from durable history metadata, or a deterministic
+    /// identity derived from the legacy segment and log position.
+    pub entry_id: String,
+    /// Timestamp copied from the durable log record that commits this entry.
+    pub timestamp: u64,
+    pub provenance: SessionEntryProvenance,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub derived_from: Vec<String>,
+    #[serde(flatten)]
+    pub data: SessionSnapshotEntryData,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub enum SessionSnapshotEntryData {
+    UserInput {
+        segments: Vec<Segment>,
+    },
+    Message {
+        role: SessionMessageRole,
+        content: Vec<SessionContentPart>,
+    },
+    ToolCall {
+        call_id: String,
+        name: String,
+        arguments: String,
+    },
+    ToolResult {
+        call_id: String,
+        summary: String,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        content: Option<String>,
+        is_error: bool,
+        #[serde(default, skip_serializing_if = "Vec::is_empty")]
+        attachments: Vec<SessionToolAttachment>,
+    },
+    SystemItem {
+        item_kind: String,
+        content: String,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[cfg_attr(feature = "typescript", ts(type = "unknown"))]
+        data: Option<serde_json::Value>,
+    },
+    RunError {
+        message: String,
+    },
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[serde(rename_all = "snake_case")]
+pub enum SessionMessageRole {
+    User,
+    Assistant,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub enum SessionContentPart {
+    Text { text: String },
+    Refusal { refusal: String },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
+pub struct SessionToolAttachment {
+    pub media_type: String,
+    /// Base64-encoded durable attachment body. Public snapshots preserve the
+    /// committed multimodal value instead of replacing it with placeholder text.
+    pub data_base64: String,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
 #[serde(tag = "event", content = "data", rename_all = "snake_case")]
 pub enum Event {
     /// A user input message was accepted, persisted as
-    /// `LogEntry::UserInput`, and is about to start a new turn.
+    /// `LogEntry::AnnotatedUserInput`, and is about to start a new turn.
     /// Broadcast to every subscribed client so TUI / GUI instances show
     /// the same user line that reconnect snapshots would replay from
     /// history; clients must not synthesize a separate pending/fake
@@ -390,7 +491,7 @@ pub enum Event {
     /// of parsing free-text prefixes like `[Notification] …` or
     /// `[File: …]`.
     ///
-    /// One event per `LogEntry::SystemItem` commit. Disk-side and
+    /// One event per `LogEntry::AnnotatedSystemItem` commit. Disk-side and
     /// wire-side are 1:1.
     SystemItem {
         #[cfg_attr(feature = "typescript", ts(type = "unknown"))]
@@ -555,8 +656,7 @@ pub enum Event {
     /// role-specific entry events (`SegmentRotated` / `SystemItem`) —
     /// there is no generic "every committed entry" broadcast.
     Snapshot {
-        #[cfg_attr(feature = "typescript", ts(type = "Array<unknown>"))]
-        entries: Vec<serde_json::Value>,
+        session: SessionSnapshot,
         greeting: Greeting,
         #[serde(default)]
         status: WorkerStatus,
@@ -589,14 +689,10 @@ pub enum Event {
     /// Server-side segment log rotated to a fresh `SegmentStart`.
     ///
     /// Fires on compaction and on auto-fork when the store head drifts
-    /// from the live writer's cached head. Clients drop their derived
-    /// view and reseed from `entry.history` exactly the way they would
-    /// from a connect-time `Snapshot`.
-    ///
-    /// Payload is the JSON form of `session_store::LogEntry::SegmentStart`.
+    /// A compaction/fork has replaced the authoritative segment. Clients drop
+    /// their derived view and reseed from the canonical committed snapshot.
     SegmentRotated {
-        #[cfg_attr(feature = "typescript", ts(type = "unknown"))]
-        entry: serde_json::Value,
+        session: SessionSnapshot,
     },
     /// Current Worker controller status. Broadcast on every controller-level
     /// transition and included in `History` snapshots for late attach.
@@ -623,11 +719,10 @@ pub enum Event {
         head_entries: usize,
         targets: Vec<RewindTarget>,
     },
-    /// A rewind has truncated the authoritative session. `entries` is the
-    /// retained session-log prefix clients should use to reseed display state.
+    /// A rewind has truncated the authoritative session. `session` is the
+    /// retained canonical snapshot clients should use to reseed display state.
     RewindApplied {
-        #[cfg_attr(feature = "typescript", ts(type = "Array<unknown>"))]
-        entries: Vec<serde_json::Value>,
+        session: SessionSnapshot,
         input: Vec<Segment>,
         summary: RewindSummary,
     },
@@ -1440,7 +1535,17 @@ mod tests {
     #[test]
     fn event_snapshot_format() {
         let event = Event::Snapshot {
-            entries: vec![serde_json::json!({"kind": "user_input", "ts": 1, "segments": []})],
+            session: SessionSnapshot {
+                entries: vec![SessionSnapshotEntry {
+                    entry_id: "entry-1".into(),
+                    timestamp: 1,
+                    provenance: SessionEntryProvenance::HumanInput,
+                    derived_from: Vec::new(),
+                    data: SessionSnapshotEntryData::UserInput {
+                        segments: Vec::new(),
+                    },
+                }],
+            },
             greeting: Greeting {
                 worker_name: "test".into(),
                 cwd: "/tmp".into(),
@@ -1458,8 +1563,12 @@ mod tests {
         let json = serde_json::to_string(&event).unwrap();
         let parsed: serde_json::Value = serde_json::from_str(&json).unwrap();
         assert_eq!(parsed["event"], "snapshot");
-        assert!(parsed["data"]["entries"].is_array());
-        assert_eq!(parsed["data"]["entries"][0]["kind"], "user_input");
+        assert!(parsed["data"]["session"]["entries"].is_array());
+        assert_eq!(
+            parsed["data"]["session"]["entries"][0]["kind"],
+            "user_input"
+        );
+        assert_eq!(parsed["data"]["session"]["entries"][0]["timestamp"], 1);
         assert_eq!(parsed["data"]["greeting"]["worker_name"], "test");
         assert_eq!(parsed["data"]["greeting"]["tools"][0], "Read");
         assert_eq!(parsed["data"]["greeting"]["context_window"], 200_000);
@@ -1469,7 +1578,7 @@ mod tests {
 
     #[test]
     fn event_snapshot_in_flight_roundtrip_and_default() {
-        let inbound = r#"{"event":"snapshot","data":{"entries":[],"greeting":{"worker_name":"test","cwd":"/tmp","provider":"p","model":"m","scope_summary":"s","tools":[]},"status":"running"}}"#;
+        let inbound = r#"{"event":"snapshot","data":{"session":{"entries":[]},"greeting":{"worker_name":"test","cwd":"/tmp","provider":"p","model":"m","scope_summary":"s","tools":[]},"status":"running"}}"#;
         let decoded: Event = serde_json::from_str(inbound).unwrap();
         match decoded {
             Event::Snapshot { in_flight, .. } => assert!(in_flight.is_empty()),
@@ -1477,7 +1586,9 @@ mod tests {
         }
 
         let event = Event::Snapshot {
-            entries: Vec::new(),
+            session: SessionSnapshot {
+                entries: Vec::new(),
+            },
             greeting: Greeting {
                 worker_name: "test".into(),
                 cwd: "/tmp".into(),
@@ -1543,15 +1654,17 @@ mod tests {
     #[test]
     fn event_segment_rotated_roundtrip() {
         let event = Event::SegmentRotated {
-            entry: serde_json::json!({"kind": "segment_start", "ts": 1, "history": []}),
+            session: SessionSnapshot {
+                entries: Vec::new(),
+            },
         };
         let json = serde_json::to_string(&event).unwrap();
         let parsed: serde_json::Value = serde_json::from_str(&json).unwrap();
         assert_eq!(parsed["event"], "segment_rotated");
-        assert_eq!(parsed["data"]["entry"]["kind"], "segment_start");
+        assert!(parsed["data"]["session"]["entries"].is_array());
         let decoded: Event = serde_json::from_str(&json).unwrap();
         match decoded {
-            Event::SegmentRotated { entry } => assert_eq!(entry["kind"], "segment_start"),
+            Event::SegmentRotated { session } => assert!(session.entries.is_empty()),
             other => panic!("expected SegmentRotated, got {other:?}"),
         }
     }
@@ -1627,8 +1740,8 @@ mod tests {
     }
 
     #[test]
-    fn event_snapshot_legacy_without_status_defaults_to_idle() {
-        let json = r#"{"event":"snapshot","data":{"entries":[],"greeting":{"worker_name":"test","cwd":"/tmp","provider":"anthropic","model":"claude","scope_summary":"","tools":[]}}}"#;
+    fn event_snapshot_without_status_defaults_to_idle() {
+        let json = r#"{"event":"snapshot","data":{"session":{"entries":[]},"greeting":{"worker_name":"test","cwd":"/tmp","provider":"anthropic","model":"claude","scope_summary":"","tools":[]}}}"#;
         let decoded: Event = serde_json::from_str(json).unwrap();
         match decoded {
             Event::Snapshot {
@@ -2039,11 +2152,11 @@ mod tests {
     }
 
     #[test]
-    fn legacy_snapshot_defaults_internal_workers_to_empty() {
+    fn snapshot_defaults_internal_workers_to_empty() {
         let snapshot: Event = serde_json::from_value(serde_json::json!({
             "event": "snapshot",
             "data": {
-                "entries": [],
+                "session": { "entries": [] },
                 "greeting": {
                     "worker_name": "parent",
                     "cwd": ".",

crates/protocol/src/typescript.rs

@@ -8,7 +8,9 @@ use crate::{
     CompletionKind, ErrorCode, Event, Greeting, InFlightBlock, InFlightSnapshot,
     InFlightToolCallState, InternalWorkerKind, InternalWorkerRef, InternalWorkerSnapshot,
     InvokeKind, MemoryWorkerEvent, Method, Permission, RewindSummary, RewindTarget, RewindTargetId,
-    RunResult, ScopeRule, Segment, ToolResultDisposition, TurnResult, WorkerEvent, WorkerStatus,
+    RunResult, ScopeRule, Segment, SessionContentPart, SessionEntryProvenance, SessionMessageRole,
+    SessionSnapshot, SessionSnapshotEntry, SessionSnapshotEntryData, SessionToolAttachment,
+    ToolResultDisposition, TurnResult, WorkerEvent, WorkerStatus,
     subscription::{
         EventSubscriptionSelector, SubscriptionEvent, SubscriptionEventPayload, SubscriptionFrame,
         SubscriptionFramePayload, SubscriptionId, SubscriptionRejectionCode, SubscriptionRequest,
@@ -63,6 +65,13 @@ pub fn generated_protocol_types() -> String {
     push_decl::<RewindSummary>(&cfg, &mut output);
     push_decl::<InFlightBlock>(&cfg, &mut output);
     push_decl::<InFlightSnapshot>(&cfg, &mut output);
+    push_decl::<SessionEntryProvenance>(&cfg, &mut output);
+    push_decl::<SessionMessageRole>(&cfg, &mut output);
+    push_decl::<SessionContentPart>(&cfg, &mut output);
+    push_decl::<SessionToolAttachment>(&cfg, &mut output);
+    push_decl::<SessionSnapshotEntryData>(&cfg, &mut output);
+    push_decl::<SessionSnapshotEntry>(&cfg, &mut output);
+    push_decl::<SessionSnapshot>(&cfg, &mut output);
     push_decl::<InternalWorkerKind>(&cfg, &mut output);
     push_decl::<InternalWorkerRef>(&cfg, &mut output);
     push_decl::<InternalWorkerSnapshot>(&cfg, &mut output);

crates/session-store/src/history.rs

@@ -2,7 +2,7 @@
 
 use serde::{Deserialize, Serialize};
 
-use crate::{LoggedItem, SessionId};
+use crate::LoggedItem;
 
 /// Stable logical identity of one model-visible history entry.
 ///
@@ -142,12 +142,15 @@ mod tests {
     #[test]
     fn annotated_segment_start_is_restore_visible_without_projecting_metadata() {
         let session_id = uuid::Uuid::now_v7();
-        let history_entry = legacy_logged_history(LoggedItem::Message {
-            role: LoggedRole::Assistant,
-            content: vec![crate::LoggedContentPart::Text {
-                text: "answer".into(),
-            }],
-        });
+        let history_entry = LoggedHistoryEntry {
+            item: LoggedItem::Message {
+                role: LoggedRole::Assistant,
+                content: vec![crate::LoggedContentPart::Text {
+                    text: "answer".into(),
+                }],
+            },
+            metadata: LoggedSessionHistoryMetadata::legacy_unknown(),
+        };
         let state = crate::collect_state(&[crate::LogEntry::AnnotatedSegmentStart {
             ts: 1,
             session_id,
@@ -160,21 +163,3 @@ mod tests {
         assert_eq!(state.history[0].as_text(), Some("answer"));
     }
 }
-
-/// Legacy Session Logs did not persist annotations. Decode helpers explicitly
-/// create `LegacyUnknown`; they never infer Human/System authority from role or
-/// plaintext.
-pub fn legacy_logged_history(item: LoggedItem) -> LoggedHistoryEntry {
-    LoggedHistoryEntry {
-        item,
-        metadata: LoggedSessionHistoryMetadata::legacy_unknown(),
-    }
-}
-
-pub fn legacy_segment_history(
-    session_id: SessionId,
-    items: impl IntoIterator<Item = LoggedItem>,
-) -> Vec<LoggedHistoryEntry> {
-    let _ = session_id;
-    items.into_iter().map(legacy_logged_history).collect()
-}

crates/session-store/src/legacy_session_log.rs

@@ -0,0 +1,188 @@
+//! Versioned decoder for Session schemas that predate canonical annotated history.
+//!
+//! These types are intentionally private to `session-store`. Current writers,
+//! replay, and public projections use [`crate::LogEntry`] exclusively; only the
+//! Worker Session schema migration is allowed to deserialize these shapes.
+
+use agen::llm_client::types::RequestConfig;
+use protocol::Segment;
+use serde::Deserialize;
+
+use crate::{
+    LogEntry, LoggedHistoryEntry, LoggedItem, LoggedSessionHistoryEntryId,
+    LoggedSessionHistoryMetadata, LoggedSessionHistoryOrigin, LoggedSystemHistoryEntry, SegmentId,
+    SegmentOrigin, SessionExtension, SessionId, SystemItem,
+};
+
+#[derive(Debug, Deserialize)]
+#[serde(tag = "kind", rename_all = "snake_case")]
+enum LegacyHistoryLogEntry {
+    SegmentStart {
+        ts: u64,
+        session_id: SessionId,
+        system_prompt: Option<String>,
+        config: RequestConfig,
+        history: Vec<LoggedItem>,
+        #[serde(default)]
+        forked_from: Option<SegmentOrigin>,
+        #[serde(default)]
+        compacted_from: Option<SegmentOrigin>,
+    },
+    UserInput {
+        ts: u64,
+        segments: Vec<Segment>,
+        #[serde(default)]
+        extensions: Vec<SessionExtension>,
+    },
+    AssistantItem {
+        ts: u64,
+        item: LoggedItem,
+    },
+    ToolResult {
+        ts: u64,
+        item: LoggedItem,
+    },
+    SystemItem {
+        ts: u64,
+        item: SystemItem,
+    },
+}
+
+/// Schema-v1 decoder. Non-history records already had their current shape, so
+/// they pass through `LogEntry`; legacy history records are converted below.
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+enum LegacySessionLogEntryV1 {
+    History(LegacyHistoryLogEntry),
+    Current(LogEntry),
+}
+
+/// Schema v2 retained the v1 history shapes while adding non-history records.
+/// Keep a distinct type so supported source versions remain explicit rather
+/// than turning migration compatibility into the current `LogEntry` contract.
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+enum LegacySessionLogEntryV2 {
+    History(LegacyHistoryLogEntry),
+    Current(LogEntry),
+}
+
+pub(crate) fn decode_entry(
+    schema_version: u32,
+    line: &str,
+    session_id: SessionId,
+    segment_id: SegmentId,
+    line_index: usize,
+) -> Result<LogEntry, serde_json::Error> {
+    let entry = match schema_version {
+        1 => match serde_json::from_str::<LegacySessionLogEntryV1>(line)? {
+            LegacySessionLogEntryV1::History(entry) => Entry::History(entry),
+            LegacySessionLogEntryV1::Current(entry) => Entry::Current(entry),
+        },
+        2 => match serde_json::from_str::<LegacySessionLogEntryV2>(line)? {
+            LegacySessionLogEntryV2::History(entry) => Entry::History(entry),
+            LegacySessionLogEntryV2::Current(entry) => Entry::Current(entry),
+        },
+        _ => unreachable!("legacy decoder called for unsupported schema {schema_version}"),
+    };
+    Ok(match entry {
+        Entry::History(entry) => {
+            canonicalize_history_entry(session_id, segment_id, line_index, entry)
+        }
+        Entry::Current(entry) => entry,
+    })
+}
+
+enum Entry {
+    History(LegacyHistoryLogEntry),
+    Current(LogEntry),
+}
+
+fn legacy_metadata(
+    segment_id: SegmentId,
+    line_index: usize,
+    item_index: usize,
+) -> LoggedSessionHistoryMetadata {
+    let mut identity = Vec::with_capacity(32);
+    identity.extend_from_slice(segment_id.as_bytes());
+    identity.extend_from_slice(&(line_index as u64).to_be_bytes());
+    identity.extend_from_slice(&(item_index as u64).to_be_bytes());
+    LoggedSessionHistoryMetadata {
+        entry_id: LoggedSessionHistoryEntryId(format!(
+            "l-{}",
+            base64::Engine::encode(&base64::engine::general_purpose::URL_SAFE_NO_PAD, identity)
+        )),
+        origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+        derivation: None,
+    }
+}
+
+fn canonicalize_history_entry(
+    _session_id: SessionId,
+    segment_id: SegmentId,
+    line_index: usize,
+    entry: LegacyHistoryLogEntry,
+) -> LogEntry {
+    match entry {
+        LegacyHistoryLogEntry::SegmentStart {
+            ts,
+            session_id,
+            system_prompt,
+            config,
+            history,
+            forked_from,
+            compacted_from,
+        } => LogEntry::AnnotatedSegmentStart {
+            ts,
+            session_id,
+            system_prompt,
+            config,
+            history: history
+                .into_iter()
+                .enumerate()
+                .map(|(item_index, item)| LoggedHistoryEntry {
+                    item,
+                    metadata: legacy_metadata(segment_id, line_index, item_index),
+                })
+                .collect(),
+            forked_from,
+            compacted_from,
+        },
+        LegacyHistoryLogEntry::UserInput {
+            ts,
+            segments,
+            extensions,
+        } => LogEntry::AnnotatedUserInput {
+            ts,
+            history: vec![LoggedHistoryEntry {
+                item: LoggedItem::from(agen::Item::user_message(Segment::flatten_to_text(
+                    &segments,
+                ))),
+                metadata: legacy_metadata(segment_id, line_index, 0),
+            }],
+            segments,
+            extensions,
+        },
+        LegacyHistoryLogEntry::AssistantItem { ts, item } => LogEntry::AnnotatedAssistantItem {
+            ts,
+            entry: LoggedHistoryEntry {
+                item,
+                metadata: legacy_metadata(segment_id, line_index, 0),
+            },
+        },
+        LegacyHistoryLogEntry::ToolResult { ts, item } => LogEntry::AnnotatedToolResult {
+            ts,
+            entry: LoggedHistoryEntry {
+                item,
+                metadata: legacy_metadata(segment_id, line_index, 0),
+            },
+        },
+        LegacyHistoryLogEntry::SystemItem { ts, item } => LogEntry::AnnotatedSystemItem {
+            ts,
+            entry: LoggedSystemHistoryEntry {
+                item,
+                metadata: legacy_metadata(segment_id, line_index, 0),
+            },
+        },
+    }
+}

crates/session-store/src/lib.rs

@@ -26,14 +26,16 @@
 //! let (session_id, segment_id) = create_segment(&store, SegmentStartState {
 //!     system_prompt: None,
 //!     config: &config,
-//!     history: &[],
+//!     history: Vec::new(),
 //! })?;
 //! ```
 
 pub mod event_trace;
 pub mod fs_store;
 pub mod history;
+mod legacy_session_log;
 pub mod logged_item;
+pub mod public_snapshot;
 pub mod segment;
 pub mod segment_log;
 pub mod store;
@@ -48,11 +50,11 @@ pub use fs_store::FsStore;
 pub use history::{
     LoggedHistoryDerivation, LoggedHistoryEntry, LoggedSessionHistoryEntryId,
     LoggedSessionHistoryMetadata, LoggedSessionHistoryOrigin, LoggedSystemHistoryEntry,
-    LoggedWorkerSubject, legacy_logged_history, legacy_segment_history,
+    LoggedWorkerSubject,
 };
 pub use logged_item::{LoggedContentPart, LoggedItem, LoggedRole, from_logged, to_logged};
 pub use segment::{
-    SegmentStartState, append_entry, append_system_item, classify_history_item,
+    SegmentStartState, append_entry, append_system_item, classify_logged_history_entry,
     create_compacted_segment, create_segment, create_segment_with_ids, ensure_head_or_fork, fork,
     fork_at, restore, restore_by_segment, save_config_changed, save_delta, save_extension,
     save_run_completed, save_run_errored, save_turn_end, save_usage, save_user_input,

crates/session-store/src/public_snapshot.rs

@@ -0,0 +1,484 @@
+use base64::{
+    Engine as _,
+    engine::general_purpose::{STANDARD as BASE64, URL_SAFE_NO_PAD},
+};
+use protocol::{
+    Segment, SessionContentPart, SessionEntryProvenance, SessionMessageRole, SessionSnapshot,
+    SessionSnapshotEntry, SessionSnapshotEntryData, SessionToolAttachment,
+};
+
+use crate::{
+    LogEntry, LoggedContentPart, LoggedHistoryEntry, LoggedItem, LoggedRole,
+    LoggedSessionHistoryOrigin, SessionId, SystemItem,
+};
+
+/// Project a complete current-segment log. A valid segment starts with one
+/// canonical annotated SegmentStart record; malformed partial input uses the
+/// nil session only to keep the public failure projection deterministic.
+pub fn project_current_session_snapshot(log: &[LogEntry]) -> SessionSnapshot {
+    let session_id = log.iter().find_map(|entry| match entry {
+        LogEntry::AnnotatedSegmentStart { session_id, .. } => Some(*session_id),
+        _ => None,
+    });
+    project_session_snapshot(session_id.unwrap_or_else(SessionId::nil), log)
+}
+
+/// Project the current durable segment into the only public session-history
+/// representation. Append-log records remain an internal persistence format.
+pub fn project_session_snapshot(session_id: SessionId, log: &[LogEntry]) -> SessionSnapshot {
+    let mut session_key = session_id;
+    let mut entries = Vec::new();
+
+    for (log_index, record) in log.iter().enumerate() {
+        match record {
+            LogEntry::AnnotatedSegmentStart {
+                ts,
+                session_id,
+                history,
+                ..
+            } => {
+                session_key = *session_id;
+                entries.clear();
+                extend_history(&mut entries, history, None, *ts);
+            }
+            LogEntry::AnnotatedUserInput {
+                ts,
+                segments,
+                history,
+                ..
+            } => extend_history(&mut entries, history, Some(segments), *ts),
+            LogEntry::AnnotatedAssistantItem { ts, entry }
+            | LogEntry::AnnotatedToolResult { ts, entry } => {
+                if let Some(data) = project_item(&entry.item) {
+                    entries.push(history_entry(entry, *ts, data));
+                }
+            }
+            LogEntry::AnnotatedSystemItem { ts, entry } => entries.push(system_entry(
+                &entry.item,
+                entry.metadata.entry_id.0.clone(),
+                *ts,
+                provenance(&entry.metadata.origin),
+                derivation_ids(entry),
+            )),
+            LogEntry::RunErrored { ts, message, .. } => entries.push(legacy_entry(
+                &session_key,
+                log_index,
+                0,
+                *ts,
+                SessionSnapshotEntryData::RunError {
+                    message: message.clone(),
+                },
+            )),
+            // Run checkpoints, configuration, usage, and extension state are
+            // controller/storage authority rather than committed conversation.
+            LogEntry::Invoke { .. }
+            | LogEntry::TurnEnd { .. }
+            | LogEntry::RunCompleted { .. }
+            | LogEntry::ActiveRunCheckpoint { .. }
+            | LogEntry::PausedTurnAbandoned { .. }
+            | LogEntry::ConfigChanged { .. }
+            | LogEntry::LlmUsage { .. }
+            | LogEntry::Extension { .. } => {}
+        }
+    }
+
+    SessionSnapshot { entries }
+}
+
+fn extend_history(
+    output: &mut Vec<SessionSnapshotEntry>,
+    history: &[LoggedHistoryEntry],
+    input_segments: Option<&Vec<Segment>>,
+    timestamp: u64,
+) {
+    let mut attached_segments = false;
+    for entry in history {
+        let data = if !attached_segments
+            && input_segments.is_some()
+            && matches!(
+                &entry.item,
+                LoggedItem::Message {
+                    role: LoggedRole::User,
+                    ..
+                }
+            ) {
+            attached_segments = true;
+            SessionSnapshotEntryData::UserInput {
+                segments: input_segments.cloned().unwrap_or_default(),
+            }
+        } else {
+            let Some(data) = project_item(&entry.item) else {
+                continue;
+            };
+            data
+        };
+        output.push(history_entry(entry, timestamp, data));
+    }
+}
+
+fn history_entry(
+    entry: &LoggedHistoryEntry,
+    timestamp: u64,
+    data: SessionSnapshotEntryData,
+) -> SessionSnapshotEntry {
+    SessionSnapshotEntry {
+        entry_id: entry.metadata.entry_id.0.clone(),
+        timestamp,
+        provenance: provenance(&entry.metadata.origin),
+        derived_from: entry
+            .metadata
+            .derivation
+            .as_ref()
+            .map(|derivation| {
+                derivation
+                    .sources
+                    .iter()
+                    .map(|source| source.0.clone())
+                    .collect()
+            })
+            .unwrap_or_default(),
+        data,
+    }
+}
+
+fn derivation_ids(entry: &crate::LoggedSystemHistoryEntry) -> Vec<String> {
+    entry
+        .metadata
+        .derivation
+        .as_ref()
+        .map(|derivation| {
+            derivation
+                .sources
+                .iter()
+                .map(|source| source.0.clone())
+                .collect()
+        })
+        .unwrap_or_default()
+}
+
+fn legacy_entry(
+    session_key: &SessionId,
+    log_index: usize,
+    item_index: usize,
+    timestamp: u64,
+    data: SessionSnapshotEntryData,
+) -> SessionSnapshotEntry {
+    SessionSnapshotEntry {
+        entry_id: legacy_entry_id(session_key, log_index, item_index),
+        timestamp,
+        provenance: SessionEntryProvenance::LegacyUnknown,
+        derived_from: Vec::new(),
+        data,
+    }
+}
+
+fn legacy_entry_id(session_key: &SessionId, log_index: usize, item_index: usize) -> String {
+    let mut identity = Vec::with_capacity(32);
+    identity.extend_from_slice(session_key.as_bytes());
+    identity.extend_from_slice(&(log_index as u64).to_be_bytes());
+    identity.extend_from_slice(&(item_index as u64).to_be_bytes());
+    format!("l-{}", URL_SAFE_NO_PAD.encode(identity))
+}
+
+fn provenance(origin: &LoggedSessionHistoryOrigin) -> SessionEntryProvenance {
+    match origin {
+        LoggedSessionHistoryOrigin::HumanInput { .. } => SessionEntryProvenance::HumanInput,
+        LoggedSessionHistoryOrigin::WorkerInput { .. } => SessionEntryProvenance::WorkerInput,
+        LoggedSessionHistoryOrigin::FlowInstruction { .. } => {
+            SessionEntryProvenance::FlowInstruction
+        }
+        LoggedSessionHistoryOrigin::BackendInstruction { .. } => {
+            SessionEntryProvenance::BackendInstruction
+        }
+        LoggedSessionHistoryOrigin::ModelOutput { .. } => SessionEntryProvenance::ModelOutput,
+        LoggedSessionHistoryOrigin::ToolOutput { .. } => SessionEntryProvenance::ToolOutput,
+        LoggedSessionHistoryOrigin::DerivedSummary => SessionEntryProvenance::DerivedSummary,
+        LoggedSessionHistoryOrigin::LegacyUnknown => SessionEntryProvenance::LegacyUnknown,
+    }
+}
+
+fn project_item(item: &LoggedItem) -> Option<SessionSnapshotEntryData> {
+    match item {
+        LoggedItem::Message { role, content } => {
+            let role = match role {
+                LoggedRole::User => SessionMessageRole::User,
+                LoggedRole::Assistant => SessionMessageRole::Assistant,
+                // System prompts and instruction history never cross the public
+                // snapshot boundary. Typed SystemItems have separate records.
+                LoggedRole::System => return None,
+            };
+            Some(SessionSnapshotEntryData::Message {
+                role,
+                content: content
+                    .iter()
+                    .map(|part| match part {
+                        LoggedContentPart::Text { text } => {
+                            SessionContentPart::Text { text: text.clone() }
+                        }
+                        LoggedContentPart::Refusal { refusal } => SessionContentPart::Refusal {
+                            refusal: refusal.clone(),
+                        },
+                    })
+                    .collect(),
+            })
+        }
+        LoggedItem::ToolCall {
+            call_id,
+            name,
+            arguments,
+        } => Some(SessionSnapshotEntryData::ToolCall {
+            call_id: call_id.clone(),
+            name: name.clone(),
+            arguments: arguments.clone(),
+        }),
+        LoggedItem::ToolResult {
+            call_id,
+            summary,
+            content,
+            is_error,
+            attachments,
+            ..
+        } => Some(SessionSnapshotEntryData::ToolResult {
+            call_id: call_id.clone(),
+            summary: summary.clone(),
+            content: content.clone(),
+            is_error: *is_error,
+            attachments: attachments
+                .iter()
+                .map(|attachment| match attachment {
+                    crate::logged_item::LoggedAttachment::Image { mime_type, data } => {
+                        SessionToolAttachment {
+                            media_type: mime_type.clone(),
+                            data_base64: BASE64.encode(data),
+                        }
+                    }
+                })
+                .collect(),
+        }),
+        // Hidden model reasoning is never observable.
+        LoggedItem::Reasoning { .. } => None,
+    }
+}
+
+fn system_entry(
+    item: &SystemItem,
+    entry_id: String,
+    timestamp: u64,
+    provenance: SessionEntryProvenance,
+    derived_from: Vec<String>,
+) -> SessionSnapshotEntry {
+    let mut data = serde_json::to_value(item).ok();
+    if let Some(serde_json::Value::Object(object)) = data.as_mut() {
+        object.remove("prompt_provenance");
+    }
+    let item_kind = data
+        .as_ref()
+        .and_then(|value| value.get("kind"))
+        .and_then(serde_json::Value::as_str)
+        .unwrap_or("system_item")
+        .to_owned();
+    SessionSnapshotEntry {
+        entry_id,
+        timestamp,
+        provenance,
+        derived_from,
+        data: SessionSnapshotEntryData::SystemItem {
+            item_kind,
+            content: item.history_text(),
+            data,
+        },
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use agen::llm_client::RequestConfig;
+
+    use super::*;
+    use crate::{
+        LoggedHistoryDerivation, LoggedSessionHistoryEntryId, LoggedSessionHistoryMetadata,
+        LoggedWorkerSubject,
+    };
+
+    #[test]
+    fn current_projection_is_stable_and_hides_reasoning_and_system_prompts() {
+        let session_id = crate::new_session_id();
+        let log = vec![LogEntry::AnnotatedSegmentStart {
+            ts: 1,
+            session_id,
+            system_prompt: None,
+            config: RequestConfig::default(),
+            history: vec![
+                LoggedItem::Message {
+                    role: LoggedRole::System,
+                    content: vec![LoggedContentPart::Text {
+                        text: "secret prompt".into(),
+                    }],
+                },
+                LoggedItem::Reasoning {
+                    text: "secret reasoning".into(),
+                    summary: Vec::new(),
+                    encrypted_content: None,
+                    signature: None,
+                },
+                LoggedItem::Message {
+                    role: LoggedRole::Assistant,
+                    content: vec![LoggedContentPart::Text {
+                        text: "visible".into(),
+                    }],
+                },
+            ]
+            .into_iter()
+            .map(|item| LoggedHistoryEntry {
+                item,
+                metadata: LoggedSessionHistoryMetadata {
+                    entry_id: LoggedSessionHistoryEntryId::new(),
+                    origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+                    derivation: None,
+                },
+            })
+            .collect(),
+            forked_from: None,
+            compacted_from: None,
+        }];
+
+        let first = project_session_snapshot(session_id, &log);
+        let second = project_session_snapshot(session_id, &log);
+        assert_eq!(first, second);
+        assert_eq!(first.entries.len(), 1);
+        assert_eq!(first.entries[0].timestamp, 1);
+        assert_eq!(
+            first.entries[0].provenance,
+            SessionEntryProvenance::LegacyUnknown
+        );
+        let json = serde_json::to_string(&first).unwrap();
+        assert!(!json.contains("secret prompt"));
+        assert!(!json.contains("secret reasoning"));
+        assert!(json.contains("visible"));
+    }
+
+    #[test]
+    fn annotated_user_input_attaches_segments_to_first_user_role_entry_for_any_origin() {
+        let session_id = crate::new_session_id();
+        let segments = vec![Segment::Text {
+            content: "normal submit".into(),
+        }];
+
+        for origin in [
+            LoggedSessionHistoryOrigin::LegacyUnknown,
+            LoggedSessionHistoryOrigin::FlowInstruction {
+                selector: "builtin:coder-review".into(),
+                definition_id: "flow-definition".into(),
+                definition_revision: 7,
+                instance_id: "flow-instance".into(),
+                state_id: "implement".into(),
+            },
+        ] {
+            let user_entry_id = LoggedSessionHistoryEntryId::new();
+            let source_entry_id = LoggedSessionHistoryEntryId::new();
+            let log = vec![
+                LogEntry::AnnotatedSegmentStart {
+                    ts: 1,
+                    session_id,
+                    system_prompt: None,
+                    config: RequestConfig::default(),
+                    history: Vec::new(),
+                    forked_from: None,
+                    compacted_from: None,
+                },
+                LogEntry::AnnotatedUserInput {
+                    ts: 2,
+                    segments: segments.clone(),
+                    history: vec![
+                        LoggedHistoryEntry {
+                            item: LoggedItem::Message {
+                                role: LoggedRole::System,
+                                content: vec![LoggedContentPart::Text {
+                                    text: "flow instruction".into(),
+                                }],
+                            },
+                            metadata: LoggedSessionHistoryMetadata {
+                                entry_id: LoggedSessionHistoryEntryId::new(),
+                                origin: LoggedSessionHistoryOrigin::FlowInstruction {
+                                    selector: "builtin:coder-review".into(),
+                                    definition_id: "flow-definition".into(),
+                                    definition_revision: 7,
+                                    instance_id: "flow-instance".into(),
+                                    state_id: "implement".into(),
+                                },
+                                derivation: None,
+                            },
+                        },
+                        LoggedHistoryEntry {
+                            item: LoggedItem::Message {
+                                role: LoggedRole::User,
+                                content: vec![LoggedContentPart::Text {
+                                    text: "normal submit".into(),
+                                }],
+                            },
+                            metadata: LoggedSessionHistoryMetadata {
+                                entry_id: user_entry_id.clone(),
+                                origin: origin.clone(),
+                                derivation: Some(LoggedHistoryDerivation {
+                                    sources: vec![source_entry_id.clone()],
+                                }),
+                            },
+                        },
+                    ],
+                    extensions: Vec::new(),
+                },
+            ];
+
+            let snapshot = project_current_session_snapshot(&log);
+            assert_eq!(snapshot.entries.len(), 1);
+            assert_eq!(snapshot.entries[0].entry_id, user_entry_id.0);
+            assert_eq!(snapshot.entries[0].provenance, provenance(&origin));
+            assert_eq!(snapshot.entries[0].derived_from, vec![source_entry_id.0]);
+            assert_eq!(
+                snapshot.entries[0].data,
+                SessionSnapshotEntryData::UserInput {
+                    segments: segments.clone(),
+                }
+            );
+        }
+    }
+
+    #[test]
+    fn annotated_projection_preserves_identity_and_provenance() {
+        let session_id = crate::new_session_id();
+        let metadata = LoggedSessionHistoryMetadata {
+            entry_id: LoggedSessionHistoryEntryId::new(),
+            origin: LoggedSessionHistoryOrigin::ModelOutput {
+                worker: LoggedWorkerSubject {
+                    workspace_id: None,
+                    runtime_id: None,
+                    worker_id: "worker".into(),
+                },
+            },
+            derivation: None,
+        };
+        let expected_id = metadata.entry_id.0.clone();
+        let log = vec![LogEntry::AnnotatedSegmentStart {
+            ts: 1,
+            session_id,
+            system_prompt: None,
+            config: RequestConfig::default(),
+            history: vec![LoggedHistoryEntry {
+                item: LoggedItem::Message {
+                    role: LoggedRole::Assistant,
+                    content: vec![LoggedContentPart::Text { text: "ok".into() }],
+                },
+                metadata,
+            }],
+            forked_from: None,
+            compacted_from: None,
+        }];
+
+        let snapshot = project_session_snapshot(session_id, &log);
+        assert_eq!(snapshot.entries[0].entry_id, expected_id);
+        assert_eq!(
+            snapshot.entries[0].provenance,
+            SessionEntryProvenance::ModelOutput
+        );
+    }
+}

crates/session-store/src/segment.rs

@@ -4,11 +4,9 @@
 //! The caller (typically Worker) holds the Engine directly and calls these
 //! functions after state-mutating operations.
 
-use crate::logged_item::{LoggedItem, to_logged};
 use crate::segment_log::{self, LogEntry, SegmentOrigin};
 use crate::store::{Store, StoreError};
-use crate::system_item::SystemItem;
-use crate::{SegmentId, SessionId};
+use crate::{LoggedHistoryEntry, LoggedSystemHistoryEntry, SegmentId, SessionId};
 use agen::EngineResult;
 use agen::llm_client::RequestConfig;
 use agen::llm_client::types::Item;
@@ -18,7 +16,7 @@ use protocol::Segment;
 pub struct SegmentStartState<'a> {
     pub system_prompt: Option<&'a str>,
     pub config: &'a RequestConfig,
-    pub history: &'a [Item],
+    pub history: Vec<LoggedHistoryEntry>,
 }
 
 /// Create a new session + initial segment, writing the initial
@@ -44,12 +42,12 @@ pub fn create_segment_with_ids(
     segment_id: SegmentId,
     state: SegmentStartState<'_>,
 ) -> Result<(), StoreError> {
-    let entry = LogEntry::SegmentStart {
+    let entry = LogEntry::AnnotatedSegmentStart {
         ts: segment_log::now_millis(),
         session_id,
         system_prompt: state.system_prompt.map(String::from),
         config: state.config.clone(),
-        history: to_logged(state.history),
+        history: state.history.to_vec(),
         forked_from: None,
         compacted_from: None,
     };
@@ -70,12 +68,12 @@ pub fn create_compacted_segment(
     source_turn_count: usize,
 ) -> Result<SegmentId, StoreError> {
     let segment_id = crate::new_segment_id();
-    let entry = LogEntry::SegmentStart {
+    let entry = LogEntry::AnnotatedSegmentStart {
         ts: segment_log::now_millis(),
         session_id: source_session_id,
         system_prompt: state.system_prompt.map(String::from),
         config: state.config.clone(),
-        history: to_logged(state.history),
+        history: state.history.to_vec(),
         forked_from: None,
         compacted_from: Some(SegmentOrigin {
             segment_id: source_segment_id,
@@ -154,12 +152,12 @@ pub fn ensure_head_or_fork(
     }
     let source_segment_id = *segment_id;
     let fork_id = crate::new_segment_id();
-    let entry = LogEntry::SegmentStart {
+    let entry = LogEntry::AnnotatedSegmentStart {
         ts: segment_log::now_millis(),
         session_id,
         system_prompt: state.system_prompt.map(String::from),
         config: state.config.clone(),
-        history: to_logged(state.history),
+        history: state.history.to_vec(),
         forked_from: Some(SegmentOrigin {
             segment_id: source_segment_id,
             at_turn_index,
@@ -183,8 +181,9 @@ pub fn save_user_input(
     session_id: SessionId,
     segment_id: SegmentId,
     segments: Vec<Segment>,
+    history: Vec<LoggedHistoryEntry>,
 ) -> Result<(), StoreError> {
-    save_user_input_with_extensions(store, session_id, segment_id, segments, Vec::new())
+    save_user_input_with_extensions(store, session_id, segment_id, segments, history, Vec::new())
 }
 
 /// Atomically persist one typed user submission and Runtime-owned session
@@ -194,15 +193,17 @@ pub fn save_user_input_with_extensions(
     session_id: SessionId,
     segment_id: SegmentId,
     segments: Vec<Segment>,
+    history: Vec<LoggedHistoryEntry>,
     extensions: Vec<segment_log::SessionExtension>,
 ) -> Result<(), StoreError> {
     append_entry(
         store,
         session_id,
         segment_id,
-        LogEntry::UserInput {
+        LogEntry::AnnotatedUserInput {
             ts: segment_log::now_millis(),
             segments,
+            history,
             extensions,
         },
     )
@@ -220,64 +221,57 @@ pub fn save_delta(
     store: &impl Store,
     session_id: SessionId,
     segment_id: SegmentId,
-    new_items: &[Item],
+    new_items: &[LoggedHistoryEntry],
 ) -> Result<(), StoreError> {
     if new_items.is_empty() {
         return Ok(());
     }
 
     let ts = segment_log::now_millis();
-    for item in new_items {
+    for entry in new_items {
+        let item = Item::from(entry.item.clone());
         if item.is_user_message() {
             // Already persisted by save_user_input at submit time.
             continue;
         }
-        let entry = classify_history_item(item, ts);
+        let entry = classify_logged_history_entry(entry.clone(), ts);
         append_entry(store, session_id, segment_id, entry)?;
     }
     Ok(())
 }
 
-/// Map one history item to its singular `LogEntry` form. Used by the
-/// fallback `save_delta` path and the controller's worker-callback
-/// classifier so write classification lives in one place.
-pub fn classify_history_item(item: &Item, ts: u64) -> LogEntry {
+/// Map one annotated history entry to its singular `LogEntry` form. Used by
+/// the fallback `save_delta` path and the controller's worker-callback
+/// classifier so write classification lives in one place without discarding
+/// identity or provenance.
+/// Map one already-annotated history entry to its singular canonical record
+/// without changing its identity or provenance.
+pub fn classify_logged_history_entry(entry: LoggedHistoryEntry, ts: u64) -> LogEntry {
+    let item = Item::from(entry.item.clone());
     if item.is_tool_result() {
-        LogEntry::ToolResult {
-            ts,
-            item: LoggedItem::from(item),
-        }
-    } else if item.is_assistant_message() || item.is_tool_call() || item.is_reasoning() {
-        LogEntry::AssistantItem {
-            ts,
-            item: LoggedItem::from(item),
-        }
+        LogEntry::AnnotatedToolResult { ts, entry }
     } else {
-        // Defensive: anything else (future Item kinds) routes through
-        // AssistantItem rather than getting silently dropped.
-        LogEntry::AssistantItem {
-            ts,
-            item: LoggedItem::from(item),
-        }
+        // Assistant messages, tool calls, reasoning, and future non-user
+        // items all use the assistant-side canonical record.
+        LogEntry::AnnotatedAssistantItem { ts, entry }
     }
 }
 
-/// Append a single typed system item as `LogEntry::SystemItem`. Helper
-/// for the Worker-side interceptor commit path; mirrors the per-item
-/// commit shape used for assistant / tool result entries.
+/// Append one typed system item and its history metadata as a canonical
+/// `LogEntry::AnnotatedSystemItem`.
 pub fn append_system_item(
     store: &impl Store,
     session_id: SessionId,
     segment_id: SegmentId,
-    item: SystemItem,
+    entry: LoggedSystemHistoryEntry,
 ) -> Result<(), StoreError> {
     append_entry(
         store,
         session_id,
         segment_id,
-        LogEntry::SystemItem {
+        LogEntry::AnnotatedSystemItem {
             ts: segment_log::now_millis(),
-            item,
+            entry,
         },
     )
 }
@@ -430,12 +424,12 @@ pub fn fork(
 ) -> Result<(SessionId, SegmentId), StoreError> {
     let session_id = crate::new_session_id();
     let fork_id = crate::new_segment_id();
-    let entry = LogEntry::SegmentStart {
+    let entry = LogEntry::AnnotatedSegmentStart {
         ts: segment_log::now_millis(),
         session_id,
         system_prompt: state.system_prompt.map(String::from),
         config: state.config.clone(),
-        history: to_logged(state.history),
+        history: state.history.to_vec(),
         forked_from: None,
         compacted_from: None,
     };
@@ -470,7 +464,7 @@ pub fn fork_at(
         // segment), before any turn completes.
         entries
             .iter()
-            .position(|e| !matches!(e, LogEntry::SegmentStart { .. }))
+            .position(|e| !matches!(e, LogEntry::AnnotatedSegmentStart { .. }))
             .unwrap_or(entries.len())
     } else {
         entries
@@ -482,12 +476,12 @@ pub fn fork_at(
     let state = segment_log::collect_state(&entries[..cut]);
 
     let fork_id = crate::new_segment_id();
-    let entry = LogEntry::SegmentStart {
+    let entry = LogEntry::AnnotatedSegmentStart {
         ts: segment_log::now_millis(),
         session_id: source_session_id,
         system_prompt: state.system_prompt,
         config: state.config,
-        history: to_logged(&state.history),
+        history: state.annotated_history,
         forked_from: Some(SegmentOrigin {
             segment_id: source_id,
             at_turn_index,

crates/session-store/src/segment_log.rs

@@ -16,7 +16,6 @@ use serde::{Deserialize, Serialize};
 
 use crate::history::{LoggedHistoryEntry, LoggedSystemHistoryEntry};
 use crate::logged_item::LoggedItem;
-use crate::system_item::SystemItem;
 
 /// A single segment log entry, serialized as one JSONL line.
 ///
@@ -50,28 +49,7 @@ impl SessionExtension {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(tag = "kind", rename_all = "snake_case")]
 pub enum LogEntry {
-    /// Segment start. Always the first entry in a segment log.
-    /// For forked segments, `history` contains the seed state from the parent.
-    SegmentStart {
-        ts: u64,
-        /// Session this segment belongs to. Compaction / fork inherits
-        /// the source segment's session_id; only fresh "new conversation"
-        /// segments mint a new session_id.
-        session_id: crate::SessionId,
-        system_prompt: Option<String>,
-        config: RequestConfig,
-        history: Vec<LoggedItem>,
-        /// Origin: forked from a sibling segment at a specific turn boundary.
-        /// The referenced segment is guaranteed to share `session_id`.
-        #[serde(default, skip_serializing_if = "Option::is_none")]
-        forked_from: Option<SegmentOrigin>,
-        /// Origin: compacted from a sibling segment at a specific turn boundary.
-        /// The referenced segment is guaranteed to share `session_id`.
-        #[serde(default, skip_serializing_if = "Option::is_none")]
-        compacted_from: Option<SegmentOrigin>,
-    },
-
-    /// Schema-v2 segment seed. Retained entries keep their stable logical
+    /// Canonical segment seed. Retained entries keep their stable logical
     /// identity and origin across fork/compaction/restore.
     AnnotatedSegmentStart {
         ts: u64,
@@ -105,22 +83,7 @@ pub enum LogEntry {
     /// restore conservatively instead of re-running a dangling tool call.
     Invoke { ts: u64, trigger: InvokeKind },
 
-    /// User input accepted at submit time. Carries the original typed
-    /// `Vec<Segment>` so clients can re-render typed atoms (paste chips,
-    /// file refs) on segment restore.
-    /// Replay flattens these into a `Item::user_message` for the worker
-    /// history; the worker layer never sees segments directly.
-    UserInput {
-        ts: u64,
-        segments: Vec<Segment>,
-        /// Typed durable state committed atomically with this input record.
-        /// Runtime-owned Flow invocation uses this to avoid a Backend-instance
-        /// commit that can get ahead of Worker history.
-        #[serde(default, skip_serializing_if = "Vec::is_empty")]
-        extensions: Vec<SessionExtension>,
-    },
-
-    /// Schema-v2 user submission with its exact model-visible entries. Typed
+    /// Canonical user submission with its exact model-visible entries. Typed
     /// Flow instructions and caller-attributed input remain separate entries.
     AnnotatedUserInput {
         ts: u64,
@@ -130,35 +93,19 @@ pub enum LogEntry {
         history: Vec<LoggedHistoryEntry>,
     },
 
-    /// Schema-v2 model output and metadata committed as one journal record.
+    /// Canonical model output and metadata committed as one journal record.
     AnnotatedAssistantItem { ts: u64, entry: LoggedHistoryEntry },
 
-    /// One assistant-side item appended to history — assistant message,
-    /// reasoning, or tool call. Singular: one entry per history item so
-    /// the wire-side `Event::*` lane and on-disk LogEntry stay 1:1.
-    AssistantItem { ts: u64, item: LoggedItem },
-
-    /// Schema-v2 tool output and metadata committed as one journal record.
+    /// Canonical tool output and metadata committed as one journal record.
     AnnotatedToolResult { ts: u64, entry: LoggedHistoryEntry },
 
-    /// One tool-execution result appended to history.
-    ToolResult { ts: u64, item: LoggedItem },
-
-    /// Schema-v2 typed system event and model-visible metadata committed
+    /// Canonical typed system event and model-visible metadata committed
     /// together.
     AnnotatedSystemItem {
         ts: u64,
         entry: LoggedSystemHistoryEntry,
     },
 
-    /// One typed agent-injected system item: notification, child-Worker
-    /// lifecycle event, `@<path>` / `/<slug>` resolution payload. Each
-    /// `SystemItem` carries kind metadata that the LLM
-    /// itself never sees (the LLM gets `Item::system_message` with the
-    /// item's denormalised `body`), but live clients and replay paths
-    /// dispatch on `kind` for typed rendering.
-    SystemItem { ts: u64, item: SystemItem },
-
     /// Turn boundary. Records the turn count after increment.
     TurnEnd { ts: u64, turn_count: usize },
 
@@ -260,6 +207,10 @@ pub struct RestoredState {
     pub system_prompt: Option<String>,
     pub config: RequestConfig,
     pub history: Vec<Item>,
+    /// Canonical persisted history with stable identity and provenance. This is
+    /// the authority for rewrites, forks, and annotated restore; `history` is
+    /// retained as the model-facing item projection.
+    pub annotated_history: Vec<LoggedHistoryEntry>,
     pub turn_count: usize,
     /// AgentTurns consumed by the active paused/yielded logical run.
     pub active_run_turn_count: Option<usize>,
@@ -276,7 +227,7 @@ pub struct RestoredState {
     /// session-store は domain を不透明扱いし、各ドメインが自前で fold する。
     pub extensions: Vec<(String, serde_json::Value)>,
     /// User submissions in original typed form, in submit order.
-    /// One entry per `LogEntry::UserInput`; the K-th entry corresponds to
+    /// One entry per `LogEntry::AnnotatedUserInput`; the K-th entry corresponds to
     /// the K-th `Item::user_message` derived during replay (modulo
     /// pre-compaction history seeded via `SegmentStart.history`, whose
     /// original segments are not preserved). Used by clients to re-render
@@ -291,6 +242,7 @@ pub fn collect_state(entries: &[LogEntry]) -> RestoredState {
         system_prompt: None,
         config: RequestConfig::default(),
         history: Vec::new(),
+        annotated_history: Vec::new(),
         turn_count: 0,
         active_run_turn_count: None,
         last_run_interrupted: false,
@@ -304,18 +256,6 @@ pub fn collect_state(entries: &[LogEntry]) -> RestoredState {
         state.entries_count += 1;
 
         match entry {
-            LogEntry::SegmentStart {
-                session_id,
-                system_prompt,
-                config,
-                history,
-                ..
-            } => {
-                state.session_id = Some(*session_id);
-                state.system_prompt = system_prompt.clone();
-                state.config = config.clone();
-                state.history = history.iter().cloned().map(Item::from).collect();
-            }
             LogEntry::AnnotatedSegmentStart {
                 session_id,
                 system_prompt,
@@ -326,6 +266,7 @@ pub fn collect_state(entries: &[LogEntry]) -> RestoredState {
                 state.session_id = Some(*session_id);
                 state.system_prompt = system_prompt.clone();
                 state.config = config.clone();
+                state.annotated_history = history.clone();
                 state.history = history
                     .iter()
                     .cloned()
@@ -338,26 +279,13 @@ pub fn collect_state(entries: &[LogEntry]) -> RestoredState {
                 state.last_run_interrupted = true;
                 state.active_run_turn_count = Some(0);
             }
-            LogEntry::UserInput {
-                segments,
-                extensions,
-                ..
-            } => {
-                let text = Segment::flatten_to_text(segments);
-                state.history.push(Item::user_message(text));
-                state.user_segments.push(segments.clone());
-                state.extensions.extend(
-                    extensions
-                        .iter()
-                        .map(|extension| (extension.domain.clone(), extension.payload.clone())),
-                );
-            }
             LogEntry::AnnotatedUserInput {
                 segments,
                 extensions,
                 history,
                 ..
             } => {
+                state.annotated_history.extend(history.iter().cloned());
                 state
                     .history
                     .extend(history.iter().cloned().map(|entry| Item::from(entry.item)));
@@ -370,20 +298,16 @@ pub fn collect_state(entries: &[LogEntry]) -> RestoredState {
             }
             LogEntry::AnnotatedAssistantItem { entry, .. }
             | LogEntry::AnnotatedToolResult { entry, .. } => {
+                state.annotated_history.push(entry.clone());
                 state.history.push(Item::from(entry.item.clone()));
             }
             LogEntry::AnnotatedSystemItem { entry, .. } => {
+                state.annotated_history.push(LoggedHistoryEntry {
+                    item: LoggedItem::from(entry.item.to_history_item()),
+                    metadata: entry.metadata.clone(),
+                });
                 state.history.push(entry.item.to_history_item());
             }
-            LogEntry::AssistantItem { item, .. } => {
-                state.history.push(Item::from(item.clone()));
-            }
-            LogEntry::ToolResult { item, .. } => {
-                state.history.push(Item::from(item.clone()));
-            }
-            LogEntry::SystemItem { item, .. } => {
-                state.history.push(item.to_history_item());
-            }
             LogEntry::TurnEnd { turn_count, .. } => {
                 if let Some(active_turn_count) = &mut state.active_run_turn_count {
                     *active_turn_count += turn_count.saturating_sub(state.turn_count);
@@ -465,6 +389,20 @@ pub fn now_millis() -> u64 {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::{
+        LoggedSessionHistoryEntryId, LoggedSessionHistoryMetadata, LoggedSessionHistoryOrigin,
+    };
+
+    fn annotated(item: Item) -> LoggedHistoryEntry {
+        LoggedHistoryEntry {
+            item: LoggedItem::from(item),
+            metadata: LoggedSessionHistoryMetadata {
+                entry_id: LoggedSessionHistoryEntryId::new(),
+                origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+                derivation: None,
+            },
+        }
+    }
 
     #[test]
     fn replay_empty() {
@@ -476,12 +414,12 @@ mod tests {
 
     #[test]
     fn replay_segment_start_sets_initial_state() {
-        let state = collect_state(&[LogEntry::SegmentStart {
+        let state = collect_state(&[LogEntry::AnnotatedSegmentStart {
             ts: 1000,
             session_id: uuid::Uuid::nil(),
             system_prompt: Some("You are helpful.".into()),
             config: RequestConfig::default().with_max_tokens(1024),
-            history: vec![Item::user_message("seed").into()],
+            history: vec![annotated(Item::user_message("seed"))],
             forked_from: None,
             compacted_from: None,
         }]);
@@ -494,7 +432,7 @@ mod tests {
     #[test]
     fn replay_full_turn() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -503,14 +441,15 @@ mod tests {
                 forked_from: None,
                 compacted_from: None,
             },
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: 2000,
                 extensions: vec![],
                 segments: vec![Segment::text("Hello")],
+                history: vec![annotated(Item::user_message("Hello"))],
             },
-            LogEntry::AssistantItem {
+            LogEntry::AnnotatedAssistantItem {
                 ts: 3000,
-                item: Item::assistant_message("Hi!").into(),
+                entry: annotated(Item::assistant_message("Hi!")),
             },
             LogEntry::TurnEnd {
                 ts: 3100,
@@ -531,7 +470,7 @@ mod tests {
     #[test]
     fn replay_incomplete_invoke_is_interrupted() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -544,14 +483,15 @@ mod tests {
                 ts: 2000,
                 trigger: InvokeKind::UserSend,
             },
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: 2001,
                 extensions: vec![],
                 segments: vec![Segment::text("run a tool")],
+                history: vec![annotated(Item::user_message("run a tool"))],
             },
-            LogEntry::AssistantItem {
+            LogEntry::AnnotatedAssistantItem {
                 ts: 3000,
-                item: Item::tool_call("call_1", "side_effect", "{}").into(),
+                entry: annotated(Item::tool_call("call_1", "side_effect", "{}")),
             },
         ]);
 
@@ -561,7 +501,7 @@ mod tests {
     #[test]
     fn replay_with_tool_calls() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -570,22 +510,27 @@ mod tests {
                 forked_from: None,
                 compacted_from: None,
             },
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: 2000,
                 extensions: vec![],
                 segments: vec![Segment::text("Check weather")],
+                history: vec![annotated(Item::user_message("Check weather"))],
             },
-            LogEntry::AssistantItem {
+            LogEntry::AnnotatedAssistantItem {
                 ts: 3000,
-                item: Item::tool_call("call_1", "get_weather", r#"{"city":"Tokyo"}"#).into(),
+                entry: annotated(Item::tool_call(
+                    "call_1",
+                    "get_weather",
+                    r#"{"city":"Tokyo"}"#,
+                )),
             },
-            LogEntry::ToolResult {
+            LogEntry::AnnotatedToolResult {
                 ts: 3500,
-                item: Item::tool_result("call_1", "Sunny, 25C").into(),
+                entry: annotated(Item::tool_result("call_1", "Sunny, 25C")),
             },
-            LogEntry::AssistantItem {
+            LogEntry::AnnotatedAssistantItem {
                 ts: 4000,
-                item: Item::assistant_message("It's sunny in Tokyo!").into(),
+                entry: annotated(Item::assistant_message("It's sunny in Tokyo!")),
             },
             LogEntry::TurnEnd {
                 ts: 4100,
@@ -599,9 +544,9 @@ mod tests {
 
     #[test]
     fn replay_restores_durable_tool_image_detail() {
-        let entry = LogEntry::ToolResult {
+        let entry = LogEntry::AnnotatedToolResult {
             ts: 3500,
-            item: Item::tool_result_item_with_attachments(
+            entry: annotated(Item::tool_result_item_with_attachments(
                 "call_image",
                 "attached",
                 None,
@@ -609,8 +554,7 @@ mod tests {
                 vec![agen::tool::Attachment::Image(
                     agen::tool::ImageAttachment::new("image/png", b"durable-image".to_vec()),
                 )],
-            )
-            .into(),
+            )),
         };
         let persisted = serde_json::to_string(&entry).unwrap();
         let restored_entry: LogEntry = serde_json::from_str(&persisted).unwrap();
@@ -630,7 +574,7 @@ mod tests {
     #[test]
     fn replay_config_changed() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -650,7 +594,7 @@ mod tests {
     #[test]
     fn replay_llm_usage_appends_to_usage_history() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -659,10 +603,11 @@ mod tests {
                 forked_from: None,
                 compacted_from: None,
             },
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: 2000,
                 extensions: vec![],
                 segments: vec![Segment::text("hi")],
+                history: vec![annotated(Item::user_message("hi"))],
             },
             LogEntry::LlmUsage {
                 ts: 2100,
@@ -672,9 +617,9 @@ mod tests {
                 cache_write_tokens: 0,
                 output_tokens: 10,
             },
-            LogEntry::AssistantItem {
+            LogEntry::AnnotatedAssistantItem {
                 ts: 2200,
-                item: Item::assistant_message("yo").into(),
+                entry: annotated(Item::assistant_message("yo")),
             },
             LogEntry::LlmUsage {
                 ts: 3100,
@@ -698,7 +643,7 @@ mod tests {
     #[test]
     fn replay_without_llm_usage_keeps_usage_history_empty() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -707,10 +652,11 @@ mod tests {
                 forked_from: None,
                 compacted_from: None,
             },
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: 2000,
                 extensions: vec![],
                 segments: vec![Segment::text("hi")],
+                history: vec![annotated(Item::user_message("hi"))],
             },
         ]);
         assert!(state.usage_history.is_empty());
@@ -771,7 +717,7 @@ mod tests {
     #[test]
     fn replay_invoke_marker_only_mutates_interrupted_state() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 0,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -784,10 +730,11 @@ mod tests {
                 ts: 100,
                 trigger: InvokeKind::UserSend,
             },
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: 101,
                 extensions: vec![],
                 segments: vec![Segment::text("hi")],
+                history: vec![annotated(Item::user_message("hi"))],
             },
             LogEntry::TurnEnd {
                 ts: 200,
@@ -806,7 +753,7 @@ mod tests {
     #[test]
     fn replay_paused_turn_abandoned_clears_interrupted_marker() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 0,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -830,7 +777,7 @@ mod tests {
     #[test]
     fn replay_restores_active_run_budget_across_compaction_checkpoint() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 0,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -861,7 +808,7 @@ mod tests {
         }))
         .expect("legacy run-completed entry");
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 0,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -924,7 +871,7 @@ mod tests {
     #[test]
     fn replay_extension_collects_domain_payload_pairs() {
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1000,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,
@@ -983,9 +930,12 @@ mod tests {
     #[test]
     fn user_input_extensions_restore_with_the_same_committed_input() {
         let segments = vec![Segment::text("Flow instructions"), Segment::text("Ticket")];
-        let entry = LogEntry::UserInput {
+        let entry = LogEntry::AnnotatedUserInput {
             ts: 9999,
             segments: segments.clone(),
+            history: vec![annotated(Item::user_message(Segment::flatten_to_text(
+                &segments,
+            )))],
             extensions: vec![SessionExtension::new(
                 "flow.runtime.v1",
                 serde_json::json!({ "state": "implement", "revision": 0 }),
@@ -1000,7 +950,7 @@ mod tests {
         assert_eq!(state.extensions[0].1["state"], "implement");
     }
 
-    /// Mixed segments survive a JSON round-trip through `LogEntry::UserInput`,
+    /// Mixed segments survive a JSON round-trip through `LogEntry::AnnotatedUserInput`,
     /// and `collect_state` derives `Item::user_message` from the flattened
     /// text while preserving the original segments separately. This covers
     /// the segments → flatten → Item replay path from the ticket.
@@ -1020,16 +970,19 @@ mod tests {
                 path: "src/main.rs".into(),
             },
         ];
-        let entry = LogEntry::UserInput {
+        let entry = LogEntry::AnnotatedUserInput {
             ts: 4242,
             extensions: vec![],
             segments: segments.clone(),
+            history: vec![annotated(Item::user_message(Segment::flatten_to_text(
+                &segments,
+            )))],
         };
         // JSON round-trip preserves the variant byte-for-byte.
         let json = serde_json::to_string(&entry).unwrap();
         let parsed: LogEntry = serde_json::from_str(&json).unwrap();
         let state = collect_state(&[
-            LogEntry::SegmentStart {
+            LogEntry::AnnotatedSegmentStart {
                 ts: 1,
                 session_id: uuid::Uuid::nil(),
                 system_prompt: None,

crates/session-store/src/system_item.rs

@@ -8,7 +8,7 @@
 //! `kind` instead of parsing text prefixes like `[Notification] …` or
 //! `[File: …]`.
 //!
-//! Persisted as the payload of [`crate::LogEntry::SystemItem`] (one
+//! Persisted as the payload of [`crate::LogEntry::AnnotatedSystemItem`] (one
 //! entry per item), and broadcast live as the payload of
 //! `Event::SystemItem` on the wire.
 //!

crates/session-store/src/worker_session_store.rs

@@ -20,7 +20,8 @@ use std::path::{Path, PathBuf};
 use std::sync::{Arc, Mutex};
 use std::time::SystemTime;
 
-const SESSION_SCHEMA_VERSION: u32 = 2;
+const SESSION_SCHEMA_VERSION: u32 = 3;
+const PREVIOUS_SESSION_SCHEMA_VERSION: u32 = 2;
 const LEGACY_SESSION_SCHEMA_VERSION: u32 = 1;
 const SESSION_FILE: &str = "session.json";
 const SEGMENTS_DIR: &str = "segments";
@@ -47,9 +48,15 @@ impl WorkerSessionStore {
             Ok(bytes) => {
                 let mut manifest: SessionManifest = serde_json::from_slice(&bytes)?;
                 match manifest.schema_version {
-                    SESSION_SCHEMA_VERSION => {}
-                    LEGACY_SESSION_SCHEMA_VERSION => {
-                        validate_legacy_segment_logs(&root)?;
+                    SESSION_SCHEMA_VERSION => {
+                        validate_canonical_segment_logs(&root)?;
+                    }
+                    PREVIOUS_SESSION_SCHEMA_VERSION | LEGACY_SESSION_SCHEMA_VERSION => {
+                        migrate_segment_logs_to_v3(
+                            &root,
+                            manifest.session_id,
+                            manifest.schema_version,
+                        )?;
                         manifest.schema_version = SESSION_SCHEMA_VERSION;
                         atomic_write_json(&root.join(SESSION_FILE), &manifest)?;
                     }
@@ -144,6 +151,41 @@ impl WorkerSessionStore {
             .join(format!("{segment_id}.trace.jsonl"))
     }
 
+    fn append_log_entry(&self, path: &Path, entry: &LogEntry) -> Result<(), StoreError> {
+        let _guard = self
+            .append_lock
+            .lock()
+            .map_err(|_| std::io::Error::other("Worker Session append lock was poisoned"))?;
+        let mut file = OpenOptions::new()
+            .create(true)
+            .read(true)
+            .write(true)
+            .append(true)
+            .open(path)?;
+        let committed_len = truncate_uncommitted_tail(&mut file)?;
+        file.seek(SeekFrom::Start(0))?;
+        let mut existing = Vec::new();
+        file.read_to_end(&mut existing)?;
+        parse_jsonl::<LogEntry>(&existing)?;
+        let line = serde_json::to_string(entry)?;
+        let mut record = Vec::with_capacity(line.len() + 1);
+        record.extend_from_slice(line.as_bytes());
+        record.push(b'\n');
+        if let Err(write_error) = file.write_all(&record) {
+            return match file.set_len(committed_len) {
+                Ok(()) => Err(write_error.into()),
+                Err(rollback_error) => Err(std::io::Error::new(
+                    rollback_error.kind(),
+                    format!(
+                        "session append failed ({write_error}) and rollback failed: {rollback_error}"
+                    ),
+                )
+                .into()),
+            };
+        }
+        Ok(())
+    }
+
     fn append_line(&self, path: &Path, line: &str) -> Result<(), StoreError> {
         let _guard = self
             .append_lock
@@ -183,7 +225,7 @@ impl Store for WorkerSessionStore {
         entry: &LogEntry,
     ) -> Result<(), StoreError> {
         self.ensure_session(session_id, true)?;
-        self.append_line(&self.log_path(segment_id), &serde_json::to_string(entry)?)
+        self.append_log_entry(&self.log_path(segment_id), entry)
     }
 
     fn read_all(
@@ -286,37 +328,138 @@ impl Store for WorkerSessionStore {
     }
 }
 
-fn validate_legacy_segment_logs(root: &Path) -> Result<(), StoreError> {
+fn segment_log_paths(root: &Path) -> Result<Vec<(SegmentId, PathBuf)>, StoreError> {
     let segments = root.join(SEGMENTS_DIR);
     if !segments.exists() {
-        return Ok(());
+        return Ok(Vec::new());
     }
+    let mut paths = Vec::new();
     for entry in fs::read_dir(&segments)? {
         let entry = entry?;
         let path = entry.path();
+        let metadata = fs::symlink_metadata(&path)?;
         let Some(name) = path.file_name().and_then(|name| name.to_str()) else {
-            continue;
+            return Err(StoreError::Corrupt {
+                line: 0,
+                message: format!("non-UTF-8 Worker Session segment path: {}", path.display()),
+            });
         };
-        if !name.ends_with(".jsonl") || name.ends_with(".trace.jsonl") {
+        if name.ends_with(".trace.jsonl") || name.starts_with('.') {
             continue;
         }
-        let contents = fs::read_to_string(&path)?;
-        for (line_index, line) in contents.lines().enumerate() {
-            if line.trim().is_empty() {
-                continue;
-            }
-            serde_json::from_str::<LogEntry>(line).map_err(|error| StoreError::Corrupt {
-                line: line_index + 1,
+        if !name.ends_with(".jsonl") {
+            continue;
+        }
+        if !metadata.file_type().is_file() {
+            return Err(StoreError::Corrupt {
+                line: 0,
                 message: format!(
-                    "cannot migrate legacy Worker Session log {}: {error}",
+                    "Worker Session segment is not a regular file: {}",
+                    path.display()
+                ),
+            });
+        }
+        let segment_id =
+            name.trim_end_matches(".jsonl")
+                .parse()
+                .map_err(|_| StoreError::Corrupt {
+                    line: 0,
+                    message: format!("invalid Worker Session segment name: {name}"),
+                })?;
+        paths.push((segment_id, path));
+    }
+    paths.sort_by_key(|(segment_id, _)| *segment_id);
+    Ok(paths)
+}
+
+fn migrate_segment_logs_to_v3(
+    root: &Path,
+    session_id: SessionId,
+    source_schema_version: u32,
+) -> Result<(), StoreError> {
+    struct MigrationPlan {
+        path: PathBuf,
+        source: Vec<u8>,
+        output: Vec<u8>,
+    }
+
+    // Phase 1 is strictly read-only. Every segment must parse and canonicalize
+    // successfully before the first authoritative byte is replaced.
+    let mut plans = Vec::new();
+    for (segment_id, path) in segment_log_paths(root)? {
+        let source = fs::read(&path)?;
+        let canonical = parse_legacy_jsonl(source_schema_version, session_id, segment_id, &source)
+            .map_err(|error| StoreError::Corrupt {
+                line: 0,
+                message: format!(
+                    "cannot migrate Worker Session log {}: {error}",
                     path.display()
                 ),
             })?;
+        let mut output = Vec::new();
+        for entry in canonical {
+            serde_json::to_writer(&mut output, &entry)?;
+            output.push(b'\n');
+        }
+        plans.push(MigrationPlan {
+            path,
+            source,
+            output,
+        });
+    }
+
+    // Fence the complete preflight snapshot before starting phase 2. Session
+    // open is the exclusive restore boundary; this additionally fails closed
+    // if an unexpected writer raced the preflight.
+    for plan in &plans {
+        if fs::read(&plan.path)? != plan.source {
+            return Err(StoreError::Corrupt {
+                line: 0,
+                message: format!(
+                    "Worker Session segment changed during migration: {}",
+                    plan.path.display()
+                ),
+            });
         }
     }
+
+    for plan in plans {
+        atomic_write_bytes(&plan.path, &plan.output)?;
+    }
     Ok(())
 }
 
+fn validate_canonical_segment_logs(root: &Path) -> Result<(), StoreError> {
+    for (_, path) in segment_log_paths(root)? {
+        let _: Vec<LogEntry> = parse_jsonl(&fs::read(&path)?)?;
+    }
+    Ok(())
+}
+
+fn parse_legacy_jsonl(
+    schema_version: u32,
+    session_id: SessionId,
+    segment_id: SegmentId,
+    bytes: &[u8],
+) -> Result<Vec<LogEntry>, serde_json::Error> {
+    let text = std::str::from_utf8(bytes).map_err(|error| {
+        serde_json::Error::io(std::io::Error::new(std::io::ErrorKind::InvalidData, error))
+    })?;
+    text.lines()
+        .enumerate()
+        .filter(|(_, line)| !line.trim().is_empty())
+        .map(|(line_index, line)| {
+            crate::legacy_session_log::decode_entry(
+                schema_version,
+                line,
+                session_id,
+                segment_id,
+                line_index,
+            )
+        })
+        .collect()
+}
+
 fn atomic_write_json<T: Serialize>(path: &Path, value: &T) -> Result<(), StoreError> {
     let mut bytes = serde_json::to_vec_pretty(value)?;
     bytes.push(b'\n');
@@ -418,7 +561,21 @@ fn truncate_uncommitted_tail(file: &mut File) -> std::io::Result<u64> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{Store, new_segment_id, new_session_id};
+    use crate::{
+        LoggedHistoryEntry, LoggedItem, LoggedSessionHistoryEntryId, LoggedSessionHistoryMetadata,
+        LoggedSessionHistoryOrigin, Store, new_segment_id, new_session_id,
+    };
+
+    fn annotated(item: agen::Item) -> LoggedHistoryEntry {
+        LoggedHistoryEntry {
+            item: LoggedItem::from(item),
+            metadata: LoggedSessionHistoryMetadata {
+                entry_id: LoggedSessionHistoryEntryId::new(),
+                origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+                derivation: None,
+            },
+        }
+    }
 
     #[test]
     fn canonical_layout_and_single_session_invariant() {
@@ -445,7 +602,7 @@ mod tests {
     }
 
     #[test]
-    fn schema_v1_logs_are_validated_and_promoted_to_v2() {
+    fn schema_v1_logs_are_rewritten_and_promoted_to_v3() {
         let root = tempfile::tempdir().unwrap();
         let session_id = new_session_id();
         let segment_id = new_segment_id();
@@ -467,7 +624,7 @@ mod tests {
     }
 
     #[test]
-    fn schema_v1_migration_rejects_corrupt_log_before_manifest_update() {
+    fn schema_v1_migration_rejects_corrupt_log_before_v3_manifest_update() {
         let root = tempfile::tempdir().unwrap();
         let session_id = new_session_id();
         let manifest = SessionManifest {
@@ -492,6 +649,280 @@ mod tests {
         assert_eq!(persisted.schema_version, LEGACY_SESSION_SCHEMA_VERSION);
     }
 
+    #[test]
+    fn schema_v2_migration_rewrites_legacy_records_with_stable_unknown_provenance() {
+        let root = tempfile::tempdir().unwrap();
+        let session_id = new_session_id();
+        let segment_id = new_segment_id();
+        fs::create_dir_all(root.path().join(SEGMENTS_DIR)).unwrap();
+        atomic_write_json(
+            &root.path().join(SESSION_FILE),
+            &SessionManifest {
+                schema_version: PREVIOUS_SESSION_SCHEMA_VERSION,
+                session_id,
+            },
+        )
+        .unwrap();
+        let source = vec![
+            serde_json::json!({
+                "kind": "segment_start",
+                "ts": 1,
+                "session_id": session_id,
+                "system_prompt": null,
+                "config": agen::llm_client::RequestConfig::default(),
+                "history": [LoggedItem::from(agen::Item::assistant_message("prior"))],
+                "forked_from": null,
+                "compacted_from": null
+            }),
+            serde_json::json!({
+                "kind": "user_input",
+                "ts": 2,
+                "segments": [{ "kind": "text", "content": "hello" }],
+                "extensions": []
+            }),
+            serde_json::json!({
+                "kind": "assistant_item",
+                "ts": 3,
+                "item": LoggedItem::from(agen::Item::assistant_message("reply"))
+            }),
+        ];
+        let path = root
+            .path()
+            .join(SEGMENTS_DIR)
+            .join(format!("{segment_id}.jsonl"));
+        let mut bytes = Vec::new();
+        for entry in source {
+            serde_json::to_writer(&mut bytes, &entry).unwrap();
+            bytes.push(b'\n');
+        }
+        fs::write(&path, bytes).unwrap();
+
+        let store = WorkerSessionStore::new(root.path()).unwrap();
+        let first = store.read_all(session_id, segment_id).unwrap();
+        assert!(matches!(first[0], LogEntry::AnnotatedSegmentStart { .. }));
+        assert!(matches!(first[1], LogEntry::AnnotatedUserInput { .. }));
+        assert!(matches!(first[2], LogEntry::AnnotatedAssistantItem { .. }));
+        let first_bytes = fs::read(&path).unwrap();
+        drop(store);
+
+        let reopened = WorkerSessionStore::new(root.path()).unwrap();
+        assert_eq!(fs::read(&path).unwrap(), first_bytes);
+        let snapshot = crate::public_snapshot::project_current_session_snapshot(
+            &reopened.read_all(session_id, segment_id).unwrap(),
+        );
+        assert_eq!(snapshot.entries.len(), 3);
+        assert_eq!(
+            snapshot
+                .entries
+                .iter()
+                .map(|entry| entry.timestamp)
+                .collect::<Vec<_>>(),
+            vec![1, 2, 3]
+        );
+        assert!(snapshot.entries.iter().all(|entry| {
+            entry.provenance == protocol::SessionEntryProvenance::LegacyUnknown
+                && entry.entry_id.len() <= 64
+        }));
+    }
+
+    #[test]
+    fn schema_v2_preflight_keeps_earlier_segments_unchanged_when_later_is_corrupt() {
+        let root = tempfile::tempdir().unwrap();
+        let session_id = new_session_id();
+        let valid_segment = uuid::Uuid::from_u128(1);
+        let corrupt_segment = uuid::Uuid::from_u128(2);
+        fs::create_dir_all(root.path().join(SEGMENTS_DIR)).unwrap();
+        atomic_write_json(
+            &root.path().join(SESSION_FILE),
+            &SessionManifest {
+                schema_version: PREVIOUS_SESSION_SCHEMA_VERSION,
+                session_id,
+            },
+        )
+        .unwrap();
+        let manifest_before = fs::read(root.path().join(SESSION_FILE)).unwrap();
+
+        let valid_path = root
+            .path()
+            .join(SEGMENTS_DIR)
+            .join(format!("{valid_segment}.jsonl"));
+        let valid_entry = serde_json::json!({
+            "kind": "segment_start",
+            "ts": 1,
+            "session_id": session_id,
+            "system_prompt": null,
+            "config": agen::llm_client::RequestConfig::default(),
+            "history": [LoggedItem::from(agen::Item::assistant_message("prior"))],
+            "forked_from": null,
+            "compacted_from": null
+        });
+        let mut valid_bytes = serde_json::to_vec(&valid_entry).unwrap();
+        valid_bytes.push(b'\n');
+        fs::write(&valid_path, &valid_bytes).unwrap();
+        let corrupt_path = root
+            .path()
+            .join(SEGMENTS_DIR)
+            .join(format!("{corrupt_segment}.jsonl"));
+        fs::write(&corrupt_path, b"{not-json}\n").unwrap();
+        let corrupt_before = fs::read(&corrupt_path).unwrap();
+
+        let error = match WorkerSessionStore::new(root.path()) {
+            Ok(_) => panic!("later corrupt segment must fail migration preflight"),
+            Err(error) => error,
+        };
+        assert!(matches!(error, StoreError::Corrupt { .. }));
+        assert_eq!(fs::read(&valid_path).unwrap(), valid_bytes);
+        assert_eq!(fs::read(&corrupt_path).unwrap(), corrupt_before);
+        assert_eq!(
+            fs::read(root.path().join(SESSION_FILE)).unwrap(),
+            manifest_before
+        );
+    }
+
+    #[test]
+    fn current_jsonl_requires_annotations_across_append_rewrite_and_reopen() {
+        let root = tempfile::tempdir().unwrap();
+        let session_id = new_session_id();
+        let segment_id = new_segment_id();
+        let store = WorkerSessionStore::new(root.path()).unwrap();
+        store
+            .create_segment(
+                session_id,
+                segment_id,
+                &[LogEntry::AnnotatedSegmentStart {
+                    ts: 1,
+                    session_id,
+                    system_prompt: None,
+                    config: agen::llm_client::RequestConfig::default(),
+                    history: vec![annotated(agen::Item::user_message("seed"))],
+                    forked_from: None,
+                    compacted_from: None,
+                }],
+            )
+            .unwrap();
+        store
+            .append(
+                session_id,
+                segment_id,
+                &LogEntry::AnnotatedAssistantItem {
+                    ts: 2,
+                    entry: annotated(agen::Item::assistant_message("reply")),
+                },
+            )
+            .unwrap();
+
+        let before_rewrite = store.read_all(session_id, segment_id).unwrap();
+        store
+            .create_segment(session_id, segment_id, &before_rewrite)
+            .unwrap();
+        drop(store);
+
+        let reopened = WorkerSessionStore::new(root.path()).unwrap();
+        let restored = reopened.read_all(session_id, segment_id).unwrap();
+        assert_eq!(
+            serde_json::to_value(&restored).unwrap(),
+            serde_json::to_value(&before_rewrite).unwrap()
+        );
+        for entry in &restored {
+            match entry {
+                LogEntry::AnnotatedSegmentStart { history, .. } => assert!(history.iter().all(
+                    |entry| !entry.metadata.entry_id.0.is_empty()
+                        && matches!(
+                            entry.metadata.origin,
+                            LoggedSessionHistoryOrigin::LegacyUnknown
+                        )
+                )),
+                LogEntry::AnnotatedAssistantItem { entry, .. } => {
+                    assert!(!entry.metadata.entry_id.0.is_empty());
+                    assert!(matches!(
+                        entry.metadata.origin,
+                        LoggedSessionHistoryOrigin::LegacyUnknown
+                    ));
+                }
+                _ => {}
+            }
+        }
+
+        let log = fs::read_to_string(reopened.log_path(segment_id)).unwrap();
+        for line in log.lines() {
+            let value: serde_json::Value = serde_json::from_str(line).unwrap();
+            let kind = value["kind"].as_str().unwrap();
+            assert!(
+                !matches!(
+                    kind,
+                    "segment_start"
+                        | "user_input"
+                        | "assistant_item"
+                        | "tool_result"
+                        | "system_item"
+                ),
+                "current-schema JSONL contains legacy history record: {kind}"
+            );
+        }
+    }
+
+    #[test]
+    fn schema_v3_rejects_legacy_records_and_new_writes_are_canonical() {
+        let root = tempfile::tempdir().unwrap();
+        let session_id = new_session_id();
+        let segment_id = new_segment_id();
+        let store = WorkerSessionStore::new(root.path()).unwrap();
+        store
+            .create_segment(
+                session_id,
+                segment_id,
+                &[LogEntry::AnnotatedSegmentStart {
+                    ts: 1,
+                    session_id,
+                    system_prompt: None,
+                    config: agen::llm_client::RequestConfig::default(),
+                    history: vec![annotated(agen::Item::assistant_message("seed"))],
+                    forked_from: None,
+                    compacted_from: None,
+                }],
+            )
+            .unwrap();
+        store
+            .append(
+                session_id,
+                segment_id,
+                &LogEntry::AnnotatedUserInput {
+                    ts: 2,
+                    segments: vec![protocol::Segment::Text {
+                        content: "new".into(),
+                    }],
+                    history: vec![annotated(agen::Item::user_message("new"))],
+                    extensions: Vec::new(),
+                },
+            )
+            .unwrap();
+        let entries = store.read_all(session_id, segment_id).unwrap();
+        assert!(matches!(entries[0], LogEntry::AnnotatedSegmentStart { .. }));
+        assert!(matches!(entries[1], LogEntry::AnnotatedUserInput { .. }));
+        drop(store);
+
+        let path = root
+            .path()
+            .join(SEGMENTS_DIR)
+            .join(format!("{segment_id}.jsonl"));
+        let mut file = OpenOptions::new().append(true).open(path).unwrap();
+        serde_json::to_writer(
+            &mut file,
+            &serde_json::json!({
+                "kind": "system_item",
+                "ts": 3,
+                "item": { "kind": "legacy_ignored", "slug": "legacy" }
+            }),
+        )
+        .unwrap();
+        file.write_all(b"\n").unwrap();
+        let error = match WorkerSessionStore::new(root.path()) {
+            Ok(_) => panic!("schema v3 must reject a legacy history record"),
+            Err(error) => error,
+        };
+        assert!(matches!(error, StoreError::Corrupt { .. }));
+    }
+
     #[test]
     fn reopen_preserves_session_and_segment_ids() {
         let root = tempfile::tempdir().unwrap();

crates/session-store/tests/fs_store_test.rs

@@ -1,12 +1,25 @@
 use agen::EngineResult;
 use agen::llm_client::types::{Item, RequestConfig};
 use session_store::{
-    FsStore, LogEntry, Store, TraceEntry, collect_state, new_segment_id, new_session_id,
+    FsStore, LogEntry, LoggedHistoryEntry, LoggedItem, LoggedSessionHistoryEntryId,
+    LoggedSessionHistoryMetadata, LoggedSessionHistoryOrigin, Store, TraceEntry, collect_state,
+    new_segment_id, new_session_id,
 };
 use std::io::Write;
 
+fn annotated(item: Item) -> LoggedHistoryEntry {
+    LoggedHistoryEntry {
+        item: LoggedItem::from(item),
+        metadata: LoggedSessionHistoryMetadata {
+            entry_id: LoggedSessionHistoryEntryId::new(),
+            origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+            derivation: None,
+        },
+    }
+}
+
 fn nil_session_start(ts: u64, session_id: uuid::Uuid) -> LogEntry {
-    LogEntry::SegmentStart {
+    LogEntry::AnnotatedSegmentStart {
         ts,
         session_id,
         system_prompt: None,
@@ -25,7 +38,7 @@ fn round_trip_write_and_read() {
     let segid = new_segment_id();
 
     let entries = vec![
-        LogEntry::SegmentStart {
+        LogEntry::AnnotatedSegmentStart {
             ts: 1000,
             session_id: sid,
             system_prompt: Some("You are helpful.".into()),
@@ -34,14 +47,15 @@ fn round_trip_write_and_read() {
             forked_from: None,
             compacted_from: None,
         },
-        LogEntry::UserInput {
+        LogEntry::AnnotatedUserInput {
             ts: 2000,
             extensions: vec![],
             segments: vec![protocol::Segment::text("Hello")],
+            history: vec![annotated(Item::user_message("Hello"))],
         },
-        LogEntry::AssistantItem {
+        LogEntry::AnnotatedAssistantItem {
             ts: 3000,
-            item: Item::assistant_message("Hi there!").into(),
+            entry: annotated(Item::assistant_message("Hi there!")),
         },
         LogEntry::TurnEnd {
             ts: 3100,
@@ -79,14 +93,14 @@ fn create_segment_writes_all_entries() {
     let sid = new_session_id();
     let segid = new_segment_id();
 
-    let entries = [LogEntry::SegmentStart {
+    let entries = [LogEntry::AnnotatedSegmentStart {
         ts: 1000,
         session_id: sid,
         system_prompt: None,
         config: RequestConfig::default(),
         history: vec![
-            Item::user_message("seed").into(),
-            Item::assistant_message("ok").into(),
+            annotated(Item::user_message("seed")),
+            annotated(Item::assistant_message("ok")),
         ],
         forked_from: None,
         compacted_from: None,
@@ -205,7 +219,7 @@ fn read_entry_count_matches_append_tally() {
     let segid = new_segment_id();
 
     let entries = [
-        LogEntry::SegmentStart {
+        LogEntry::AnnotatedSegmentStart {
             ts: 1000,
             session_id: sid,
             system_prompt: None,
@@ -214,10 +228,11 @@ fn read_entry_count_matches_append_tally() {
             forked_from: None,
             compacted_from: None,
         },
-        LogEntry::UserInput {
+        LogEntry::AnnotatedUserInput {
             ts: 2000,
             extensions: vec![],
             segments: vec![protocol::Segment::text("Hello")],
+            history: vec![annotated(Item::user_message("Hello"))],
         },
     ];
 
@@ -254,10 +269,11 @@ fn unterminated_utf8_tail_is_ignored_and_replaced_on_append() {
     assert_eq!(store.read_all(sid, segid).unwrap().len(), 1);
     assert_eq!(store.read_entry_count(sid, segid).unwrap(), 1);
 
-    let next = LogEntry::UserInput {
+    let next = LogEntry::AnnotatedUserInput {
         ts: 2,
         extensions: vec![],
         segments: vec![protocol::Segment::text("recovered")],
+        history: vec![annotated(Item::user_message("recovered"))],
     };
     store.append(sid, segid, &next).unwrap();
 

crates/session-store/tests/session_test.rs

@@ -16,6 +16,21 @@ use session_store::{FsStore, LogEntry, SegmentStartState, Store, collect_state};
 // Helpers
 // =============================================================================
 
+fn annotated(items: &[Item]) -> Vec<session_store::LoggedHistoryEntry> {
+    items
+        .iter()
+        .cloned()
+        .map(|item| session_store::LoggedHistoryEntry {
+            item: session_store::LoggedItem::from(item),
+            metadata: session_store::LoggedSessionHistoryMetadata {
+                entry_id: session_store::LoggedSessionHistoryEntryId::new(),
+                origin: session_store::LoggedSessionHistoryOrigin::LegacyUnknown,
+                derivation: None,
+            },
+        })
+        .collect()
+}
+
 fn simple_text_events() -> Vec<Event> {
     vec![
         Event::text_block_start(0),
@@ -144,6 +159,7 @@ async fn run_and_persist(
         session_id,
         segment_id,
         vec![protocol::Segment::text(input)],
+        annotated(&[Item::user_message(input)]),
     )
     .unwrap();
 
@@ -154,8 +170,8 @@ async fn run_and_persist(
     worker.engine = locked.unlock();
 
     let projected = worker.history();
-    let new_items = &projected[history_before..];
-    session_store::save_delta(store, session_id, segment_id, new_items).unwrap();
+    let new_items = annotated(&projected[history_before..]);
+    session_store::save_delta(store, session_id, segment_id, &new_items).unwrap();
     session_store::save_turn_end(store, session_id, segment_id, worker.turn_count()).unwrap();
 
     match &result {
@@ -219,7 +235,7 @@ async fn session_run_logs_entries() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -237,7 +253,10 @@ async fn session_run_logs_entries() {
     );
 
     // First entry is SegmentStart
-    assert!(matches!(&entries[0], LogEntry::SegmentStart { .. }));
+    assert!(matches!(
+        &entries[0],
+        LogEntry::AnnotatedSegmentStart { .. }
+    ));
 
     // Has a RunCompleted with Finished
     let has_finished = entries.iter().any(|e| {
@@ -264,7 +283,7 @@ async fn session_restore_round_trip() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -303,7 +322,7 @@ async fn session_run_with_tool_call() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -314,12 +333,12 @@ async fn session_run_with_tool_call() {
 
     let has_tool_results = entries
         .iter()
-        .any(|e| matches!(e, LogEntry::ToolResult { .. }));
+        .any(|e| matches!(e, LogEntry::AnnotatedToolResult { .. }));
     assert!(has_tool_results, "should have ToolResult entry");
 
     let has_assistant = entries
         .iter()
-        .any(|e| matches!(e, LogEntry::AssistantItem { .. }));
+        .any(|e| matches!(e, LogEntry::AnnotatedAssistantItem { .. }));
     assert!(has_assistant, "should have AssistantItem entry");
 }
 
@@ -338,7 +357,7 @@ async fn session_resume_after_pause() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -377,7 +396,7 @@ async fn session_fork_creates_new_session() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -390,7 +409,7 @@ async fn session_fork_creates_new_session() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -399,7 +418,10 @@ async fn session_fork_creates_new_session() {
     // Fork should have a SegmentStart with the current history
     let fork_entries = store.read_all(fork_sid, fork_segid).unwrap();
     assert_eq!(fork_entries.len(), 1);
-    assert!(matches!(&fork_entries[0], LogEntry::SegmentStart { .. }));
+    assert!(matches!(
+        &fork_entries[0],
+        LogEntry::AnnotatedSegmentStart { .. }
+    ));
 
     let fork_state = collect_state(&fork_entries);
     assert_eq!(fork_state.session_id, Some(fork_sid));
@@ -418,7 +440,7 @@ async fn session_fork_at_truncates_within_session() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -445,6 +467,23 @@ async fn session_fork_at_truncates_within_session() {
         .expect("source segment has the matching TurnEnd");
     let source_state_at_fork = collect_state(&all_entries[..=turn_end_pos]);
     assert_eq!(fork_state.history.len(), source_state_at_fork.history.len());
+    assert_eq!(
+        fork_state.annotated_history, source_state_at_fork.annotated_history,
+        "fork_at must preserve every retained history entry identity and provenance",
+    );
+    assert!(fork_state.annotated_history.iter().all(|entry| {
+        !entry.metadata.entry_id.0.is_empty()
+            && matches!(
+                entry.metadata.origin,
+                session_store::LoggedSessionHistoryOrigin::LegacyUnknown
+                    | session_store::LoggedSessionHistoryOrigin::HumanInput { .. }
+                    | session_store::LoggedSessionHistoryOrigin::WorkerInput { .. }
+                    | session_store::LoggedSessionHistoryOrigin::BackendInstruction { .. }
+                    | session_store::LoggedSessionHistoryOrigin::ModelOutput { .. }
+                    | session_store::LoggedSessionHistoryOrigin::ToolOutput { .. }
+                    | session_store::LoggedSessionHistoryOrigin::DerivedSummary
+            )
+    }));
 
     // list_segments should show both source and fork in the same Session.
     let segs = store.list_segments(sid).unwrap();
@@ -463,7 +502,7 @@ async fn session_config_changed_logged() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -496,7 +535,7 @@ async fn session_auto_forks_on_conflict() {
         SegmentStartState {
             system_prompt: worker_a.get_system_prompt(),
             config: worker_a.request_config(),
-            history: &worker_a.history(),
+            history: annotated(&worker_a.history()),
         },
     )
     .unwrap();
@@ -505,12 +544,14 @@ async fn session_auto_forks_on_conflict() {
     let mut entries_written: usize = 1;
 
     // Simulate another Worker writing to the same segment behind our back.
-    let extra_entry = LogEntry::UserInput {
-        ts: 9999,
-        extensions: vec![],
-        segments: vec![protocol::Segment::text("Interloper")],
-    };
-    store.append(sid, original_segid, &extra_entry).unwrap();
+    session_store::save_user_input(
+        &store,
+        sid,
+        original_segid,
+        vec![protocol::Segment::text("Interloper")],
+        annotated(&[Item::user_message("Interloper")]),
+    )
+    .unwrap();
 
     // Now the on-disk count exceeds our tally — ensure_head_or_fork should auto-fork.
     session_store::ensure_head_or_fork(
@@ -522,7 +563,7 @@ async fn session_auto_forks_on_conflict() {
         SegmentStartState {
             system_prompt: worker_a.get_system_prompt(),
             config: worker_a.request_config(),
-            history: &worker_a.history(),
+            history: annotated(&worker_a.history()),
         },
     )
     .unwrap();
@@ -543,7 +584,7 @@ async fn session_auto_forks_on_conflict() {
     // The new segment records its lineage forward via forked_from; the
     // source segment is left immutable (no terminal marker written back).
     match &fork_entries[0] {
-        LogEntry::SegmentStart {
+        LogEntry::AnnotatedSegmentStart {
             forked_from: Some(origin),
             ..
         } => {
@@ -563,7 +604,7 @@ async fn session_auto_forks_on_conflict() {
     );
     let has_interloper = original_entries
         .iter()
-        .any(|e| matches!(e, LogEntry::UserInput { .. }));
+        .any(|e| matches!(e, LogEntry::AnnotatedUserInput { .. }));
     assert!(has_interloper);
 }
 
@@ -581,7 +622,7 @@ async fn nested_past_fork_leaves_ancestors_immutable() {
         SegmentStartState {
             system_prompt: worker.get_system_prompt(),
             config: worker.request_config(),
-            history: &worker.history(),
+            history: annotated(&worker.history()),
         },
     )
     .unwrap();
@@ -618,7 +659,7 @@ async fn nested_past_fork_leaves_ancestors_immutable() {
 
     // fork2's lineage points at fork1, not the root.
     match &store.read_all(sid, fork2).unwrap()[0] {
-        LogEntry::SegmentStart {
+        LogEntry::AnnotatedSegmentStart {
             forked_from: Some(origin),
             ..
         } => assert_eq!(origin.segment_id, fork1),

crates/tui/src/app.rs

@@ -765,7 +765,7 @@ impl App {
 
     fn method_for_run(&mut self, segments: Vec<Segment>) -> Method {
         // TurnHeader / UserMessage blocks are pushed only after the Worker
-        // emits `Event::UserMessage` from a committed `LogEntry::UserInput`.
+        // emits `Event::UserMessage` from a committed `LogEntry::AnnotatedUserInput`.
         // Locally we only clear the input buffer and forward the method,
         // while remembering enough local state to undo the visible submit if
         // the accepted run produced no assistant output and was rolled back.
@@ -1098,10 +1098,9 @@ impl App {
                 self.blocks.push(Block::UserMessage { segments });
                 self.assistant_streaming = false;
             }
-            Event::SegmentRotated { entry } => {
+            Event::SegmentRotated { session } => {
                 let retained_run_errors = self.run_error_messages.clone();
-                self.reset_for_rotation();
-                self.apply_log_entry_raw(&entry);
+                self.restore_session(&session, self.greeting.clone());
                 for message in retained_run_errors {
                     self.blocks.push(Block::Alert {
                         level: AlertLevel::Error,
@@ -1408,14 +1407,14 @@ impl App {
                 self.latest_memory_worker_event = Some(event.message);
             }
             Event::Snapshot {
-                entries,
+                session,
                 greeting,
                 status,
                 in_flight,
                 internal_workers,
             } => {
                 self.rewind_refresh_fence = false;
-                self.restore_snapshot(&entries, greeting, in_flight);
+                self.restore_snapshot(&session, greeting, in_flight);
                 self.replace_internal_worker_snapshots(internal_workers);
                 self.set_worker_status(status);
             }
@@ -1455,11 +1454,11 @@ impl App {
                 }
             }
             Event::RewindApplied {
-                entries,
+                session,
                 input,
                 summary,
             } => {
-                self.restore_rewind_snapshot(&entries);
+                self.restore_rewind_snapshot(&session);
                 self.rewind_refresh_fence = true;
                 let restored_composer = if self.input.is_empty() {
                     self.input.replace_with_segments(&input);
@@ -2173,7 +2172,7 @@ impl App {
     ) -> InternalWorkerView {
         let mut app = App::new(snapshot.worker.name.clone());
         app.mode = mode;
-        app.restore_entries(&snapshot.entries, None);
+        app.restore_session(&snapshot.session, None);
         app.apply_in_flight_snapshot(snapshot.in_flight);
         app.set_worker_status(snapshot.status);
         if let Some(error) = snapshot.error {
@@ -2254,14 +2253,14 @@ impl App {
 
     fn restore_snapshot(
         &mut self,
-        entries: &[serde_json::Value],
+        session: &protocol::SessionSnapshot,
         greeting: protocol::Greeting,
         in_flight: InFlightSnapshot,
     ) {
         self.greeting = Some(greeting.clone());
         self.context_window = greeting.context_window;
         self.session_context_tokens = greeting.context_tokens;
-        self.restore_entries(entries, Some(greeting));
+        self.restore_session(session, Some(greeting));
         self.apply_in_flight_snapshot(in_flight);
     }
 
@@ -2270,7 +2269,7 @@ impl App {
     /// session tail; always clear/replay from it even if this TUI instance has
     /// somehow lost connect-time greeting metadata. Skipping the restore in
     /// that case would leave old post-target output visible after success.
-    fn restore_rewind_snapshot(&mut self, entries: &[serde_json::Value]) {
+    fn restore_rewind_snapshot(&mut self, session: &protocol::SessionSnapshot) {
         let greeting = self.greeting.clone().or_else(|| {
             self.blocks.iter().find_map(|b| match b {
                 Block::Greeting(g) => Some(g.clone()),
@@ -2283,7 +2282,7 @@ impl App {
             self.session_context_tokens = greeting.context_tokens;
         }
         let missing_greeting = greeting.is_none();
-        self.restore_entries(entries, greeting);
+        self.restore_session(session, greeting);
         if missing_greeting {
             self.blocks.push(Block::Alert {
                 level: AlertLevel::Warn,
@@ -2293,9 +2292,9 @@ impl App {
         }
     }
 
-    fn restore_entries(
+    fn restore_session(
         &mut self,
-        entries: &[serde_json::Value],
+        session: &protocol::SessionSnapshot,
         greeting: Option<protocol::Greeting>,
     ) {
         self.run_error_messages.clear();
@@ -2309,137 +2308,90 @@ impl App {
         }
         self.assistant_streaming = false;
 
-        for entry in entries {
-            self.apply_log_entry_raw(entry);
+        for entry in &session.entries {
+            use protocol::{SessionContentPart, SessionMessageRole, SessionSnapshotEntryData};
+            match &entry.data {
+                SessionSnapshotEntryData::UserInput { segments } => {
+                    self.turn_index += 1;
+                    self.blocks.push(Block::TurnHeader {
+                        turn: self.turn_index,
+                    });
+                    if !segments.is_empty() {
+                        self.blocks.push(Block::UserMessage {
+                            segments: segments.clone(),
+                        });
+                    }
+                }
+                SessionSnapshotEntryData::Message { role, content } => {
+                    let role = match role {
+                        SessionMessageRole::User => agen::Role::User,
+                        SessionMessageRole::Assistant => agen::Role::Assistant,
+                    };
+                    let item = agen::Item::Message {
+                        id: None,
+                        role,
+                        content: content
+                            .iter()
+                            .map(|part| match part {
+                                SessionContentPart::Text { text } => {
+                                    agen::ContentPart::Text { text: text.clone() }
+                                }
+                                SessionContentPart::Refusal { refusal } => {
+                                    agen::ContentPart::Refusal {
+                                        refusal: refusal.clone(),
+                                    }
+                                }
+                            })
+                            .collect(),
+                        status: None,
+                    };
+                    let value = serde_json::to_value(item).expect("Item is Serialize");
+                    self.push_history_item(&value);
+                }
+                SessionSnapshotEntryData::ToolCall {
+                    call_id,
+                    name,
+                    arguments,
+                } => {
+                    let item =
+                        agen::Item::tool_call(call_id.clone(), name.clone(), arguments.clone());
+                    let value = serde_json::to_value(item).expect("Item is Serialize");
+                    self.push_history_item(&value);
+                }
+                SessionSnapshotEntryData::ToolResult {
+                    call_id,
+                    summary,
+                    content,
+                    is_error,
+                    ..
+                } => {
+                    let item = agen::Item::tool_result_item(
+                        call_id.clone(),
+                        summary.clone(),
+                        content.clone(),
+                        *is_error,
+                    );
+                    let value = serde_json::to_value(item).expect("Item is Serialize");
+                    self.push_history_item(&value);
+                }
+                SessionSnapshotEntryData::SystemItem { data, .. } => {
+                    if let Some(data) = data {
+                        self.apply_system_item(data);
+                    }
+                }
+                SessionSnapshotEntryData::RunError { message } => {
+                    self.push_run_error(message.clone());
+                }
+            }
         }
-
         self.mark_orphan_tool_calls_incomplete_pass();
     }
 
-    /// Drop the derived view in preparation for replaying a new
-    /// `SegmentStart` (compaction / fork). Greeting is preserved
-    /// because the Worker identity hasn't changed.
-    fn reset_for_rotation(&mut self) {
-        let greeting = self.blocks.iter().find_map(|b| match b {
-            Block::Greeting(g) => Some(g.clone()),
-            _ => None,
-        });
-        self.turn_index = 0;
-        self.blocks.clear();
-        self.cache = FileCache::new();
-        self.task_store = TaskStore::new();
-        self.task_pane_scroll = 0;
-        if let Some(g) = greeting {
-            self.greeting = Some(g.clone());
-            self.blocks.push(Block::Greeting(g));
-        }
-    }
-
-    /// Walk a single `LogEntry` JSON value and translate it into blocks
-    /// the live event path would have produced. Shared between
-    /// `restore_snapshot` (replay path) and `apply_log_entry` (live
-    /// path).
-    fn apply_log_entry_raw(&mut self, value: &serde_json::Value) {
-        let Ok(entry) = serde_json::from_value::<session_store::LogEntry>(value.clone()) else {
-            return;
-        };
-        match entry {
-            session_store::LogEntry::SegmentStart { history, .. } => {
-                for logged in history {
-                    let item: agen::Item = logged.into();
-                    let item_value = serde_json::to_value(&item).expect("Item is Serialize");
-                    self.push_history_item(&item_value);
-                }
-            }
-            session_store::LogEntry::UserInput { segments, .. } => {
-                self.turn_index += 1;
-                self.blocks.push(Block::TurnHeader {
-                    turn: self.turn_index,
-                });
-                if !segments.is_empty() {
-                    self.blocks.push(Block::UserMessage { segments });
-                }
-            }
-            session_store::LogEntry::AssistantItem { item, .. }
-            | session_store::LogEntry::ToolResult { item, .. } => {
-                let it: agen::Item = item.into();
-                let item_value = serde_json::to_value(&it).expect("Item is Serialize");
-                self.push_history_item(&item_value);
-            }
-            session_store::LogEntry::SystemItem { item, .. } => {
-                let value = serde_json::to_value(&item).expect("SystemItem is Serialize");
-                self.apply_system_item(&value);
-            }
-            session_store::LogEntry::Extension {
-                domain, payload, ..
-            } if domain == "yoi.compaction" => {
-                self.apply_compaction_extension(&payload);
-            }
-            session_store::LogEntry::RunErrored { message, .. } => {
-                self.push_run_error(message);
-            }
-            // Non-history-bearing variants don't affect the block view.
-            _ => {}
-        }
-    }
-
     /// Dispatch one `SystemItem` JSON value into the appropriate block.
     ///
     /// Kind-based routing replaces the old free-text `[Notification]` /
     /// `[File: …]` parsing path: each kind maps directly to a typed
     /// block (`Block::Notify`, `Block::WorkerEvent`, …).
-    fn apply_compaction_extension(&mut self, payload: &serde_json::Value) {
-        if payload.get("kind").and_then(|value| value.as_str()) != Some("compaction_block") {
-            return;
-        }
-        match payload.get("state").and_then(|value| value.as_str()) {
-            Some("running") => {
-                if self.last_streaming_compact_mut().is_none() {
-                    self.blocks.push(Block::Compact(CompactEvent::Streaming {
-                        started_at: Instant::now(),
-                    }));
-                }
-            }
-            Some("done") => {
-                let new_segment_id = payload
-                    .get("new_segment_id")
-                    .and_then(|value| value.as_str())
-                    .and_then(|value| value.parse::<uuid::Uuid>().ok())
-                    .unwrap_or_else(uuid::Uuid::nil);
-                if let Some(evt) = self.last_streaming_compact_mut() {
-                    *evt = CompactEvent::Done {
-                        new_segment_id,
-                        elapsed_secs: None,
-                    };
-                } else {
-                    self.blocks.push(Block::Compact(CompactEvent::Done {
-                        new_segment_id,
-                        elapsed_secs: None,
-                    }));
-                }
-            }
-            Some("failed") => {
-                let error = payload
-                    .get("error")
-                    .and_then(|value| value.as_str())
-                    .unwrap_or("compact failed")
-                    .to_string();
-                if let Some(evt) = self.last_streaming_compact_mut() {
-                    *evt = CompactEvent::Failed {
-                        error,
-                        elapsed_secs: None,
-                    };
-                } else {
-                    self.blocks.push(Block::Compact(CompactEvent::Failed {
-                        error,
-                        elapsed_secs: None,
-                    }));
-                }
-            }
-            _ => {}
-        }
-    }
-
     fn apply_system_item(&mut self, value: &serde_json::Value) {
         let Ok(item) = serde_json::from_value::<session_store::SystemItem>(value.clone()) else {
             // Unknown / forward-compat shape: fall back to rendering the
@@ -2542,6 +2494,15 @@ fn fmt_millis(ms: u64) -> String {
     }
 }
 
+#[cfg(test)]
+fn public_session(values: Vec<serde_json::Value>) -> protocol::SessionSnapshot {
+    let entries = values
+        .into_iter()
+        .map(|value| serde_json::from_value(value).expect("LogEntry deserializes"))
+        .collect::<Vec<session_store::LogEntry>>();
+    session_store::public_snapshot::project_current_session_snapshot(&entries)
+}
+
 fn message_text(item: &serde_json::Value) -> String {
     item["content"]
         .as_array()
@@ -2685,7 +2646,7 @@ mod rewind_refresh_tests {
         });
 
         app.handle_worker_event(Event::RewindApplied {
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             input: vec![Segment::text("selected rewind input")],
             summary: summary(3),
         });
@@ -2704,7 +2665,7 @@ mod rewind_refresh_tests {
         });
 
         app.handle_worker_event(Event::RewindApplied {
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             input: vec![Segment::text("rewound input")],
             summary: summary(1),
         });
@@ -2747,7 +2708,7 @@ mod rewind_refresh_tests {
         });
 
         app.handle_worker_event(Event::RewindApplied {
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             input: vec![Segment::text("rewound input")],
             summary: summary(2),
         });
@@ -2976,6 +2937,17 @@ mod composer_history_persistence_tests {
 mod completion_flow_tests {
     use super::*;
 
+    fn annotated(item: agen::Item) -> session_store::LoggedHistoryEntry {
+        session_store::LoggedHistoryEntry {
+            item: session_store::LoggedItem::from(item),
+            metadata: session_store::LoggedSessionHistoryMetadata {
+                entry_id: session_store::LoggedSessionHistoryEntryId::new(),
+                origin: session_store::LoggedSessionHistoryOrigin::LegacyUnknown,
+                derivation: None,
+            },
+        }
+    }
+
     #[test]
     fn typing_at_creates_completion_state_and_emits_query() {
         let mut app = App::new("test".into());
@@ -3278,7 +3250,7 @@ mod completion_flow_tests {
     #[test]
     fn committed_user_message_survives_fresh_segment_rotation() {
         let mut app = App::new("test".into());
-        let start = session_store::LogEntry::SegmentStart {
+        let start = session_store::LogEntry::AnnotatedSegmentStart {
             ts: session_store::segment_log::now_millis(),
             session_id: uuid::Uuid::nil(),
             system_prompt: None,
@@ -3289,7 +3261,9 @@ mod completion_flow_tests {
         };
 
         app.handle_worker_event(Event::SegmentRotated {
-            entry: serde_json::to_value(start).expect("LogEntry is Serialize"),
+            session: public_session(vec![
+                serde_json::to_value(start).expect("LogEntry is Serialize"),
+            ]),
         });
         app.handle_worker_event(Event::UserMessage {
             segments: vec![Segment::text("first persisted message")],
@@ -3533,23 +3507,23 @@ mod completion_flow_tests {
     }
 
     #[test]
-    fn snapshot_renders_system_message_block_from_session_start() {
+    fn snapshot_excludes_system_prompt_history_from_public_blocks() {
         let mut app = App::new("test".into());
-        let session_start = session_store::LogEntry::SegmentStart {
+        let session_start = session_store::LogEntry::AnnotatedSegmentStart {
             ts: 1,
             session_id: uuid::Uuid::nil(),
             system_prompt: None,
             config: Default::default(),
-            history: vec![session_store::LoggedItem::from(
-                &agen::Item::system_message("[File: src/main.rs]\nfn main() {}"),
-            )],
+            history: vec![annotated(agen::Item::system_message(
+                "[File: src/main.rs]\nfn main() {}",
+            ))],
             forked_from: None,
             compacted_from: None,
         };
         let session_start_value = serde_json::to_value(&session_start).unwrap();
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: vec![session_start_value],
+            session: public_session(vec![session_start_value]),
             status: WorkerStatus::Running,
             in_flight: Default::default(),
             internal_workers: Vec::new(),
@@ -3557,10 +3531,8 @@ mod completion_flow_tests {
 
         assert!(matches!(app.worker_status, WorkerStatus::Running));
         assert!(app.running);
-        assert!(matches!(
-            app.blocks.get(1),
-            Some(Block::SystemMessage { text }) if text == "[File: src/main.rs]\nfn main() {}"
-        ));
+        assert_eq!(app.blocks.len(), 1);
+        assert!(matches!(app.blocks.first(), Some(Block::Greeting(_))));
     }
 
     #[test]
@@ -3595,7 +3567,7 @@ mod completion_flow_tests {
         };
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: vec![serde_json::to_value(run_errored).unwrap()],
+            session: public_session(vec![serde_json::to_value(run_errored).unwrap()]),
             status: WorkerStatus::Idle,
             in_flight: Default::default(),
             internal_workers: Vec::new(),
@@ -3623,7 +3595,7 @@ mod completion_flow_tests {
             code: ErrorCode::ProviderError,
             message: "provider unavailable".into(),
         });
-        let segment_start = session_store::LogEntry::SegmentStart {
+        let segment_start = session_store::LogEntry::AnnotatedSegmentStart {
             ts: 5,
             session_id: uuid::Uuid::nil(),
             system_prompt: None,
@@ -3633,7 +3605,7 @@ mod completion_flow_tests {
             compacted_from: None,
         };
         app.handle_worker_event(Event::SegmentRotated {
-            entry: serde_json::to_value(segment_start).unwrap(),
+            session: public_session(vec![serde_json::to_value(segment_start).unwrap()]),
         });
 
         let errors = app
@@ -3656,7 +3628,9 @@ mod completion_flow_tests {
         let mut app = App::new("test".into());
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             status: WorkerStatus::Running,
             in_flight: InFlightSnapshot {
                 blocks: vec![
@@ -3762,7 +3736,9 @@ mod completion_flow_tests {
             },
             revision,
             status: WorkerStatus::Idle,
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             in_flight: protocol::InFlightSnapshot::default(),
             error: None,
             internal_workers: Vec::new(),
@@ -3977,7 +3953,9 @@ mod completion_flow_tests {
         assert_eq!(app.selected_worker_view().worker_name, "parent");
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             status: WorkerStatus::Idle,
             in_flight: Default::default(),
             internal_workers: Vec::new(),
@@ -4026,7 +4004,9 @@ mod completion_flow_tests {
         });
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             status: WorkerStatus::Idle,
             in_flight: Default::default(),
             internal_workers: vec![InternalWorkerSnapshot {
@@ -4037,7 +4017,9 @@ mod completion_flow_tests {
                     kind: protocol::InternalWorkerKind::SubWorker,
                 },
                 revision: 4,
-                entries: Vec::new(),
+                session: protocol::SessionSnapshot {
+                    entries: Vec::new(),
+                },
                 status: WorkerStatus::Running,
                 error: None,
                 in_flight: Default::default(),
@@ -4193,7 +4175,9 @@ mod completion_flow_tests {
         greeting.context_tokens = 45_000;
 
         app.handle_worker_event(Event::Snapshot {
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             greeting,
             status: WorkerStatus::Idle,
             in_flight: Default::default(),
@@ -4363,40 +4347,37 @@ mod completion_flow_tests {
         });
 
         let assistant_item_entries = vec![
-            serde_json::json!({
-                "kind": "assistant_item",
-                "ts": 1,
-                "item": {
-                    "kind": "tool_call",
-                    "call_id": "c1",
-                    "name": "TaskCreate",
-                    "arguments": r#"{"subject":"a","description":"A"}"#,
-                },
-            }),
-            serde_json::json!({
-                "kind": "assistant_item",
-                "ts": 2,
-                "item": {
-                    "kind": "tool_call",
-                    "call_id": "c2",
-                    "name": "TaskCreate",
-                    "arguments": r#"{"subject":"b","description":"B"}"#,
-                },
-            }),
-            serde_json::json!({
-                "kind": "assistant_item",
-                "ts": 3,
-                "item": {
-                    "kind": "tool_call",
-                    "call_id": "u1",
-                    "name": "TaskUpdate",
-                    "arguments": r#"{"taskid":2,"status":"inprogress"}"#,
-                },
-            }),
+            serde_json::to_value(session_store::LogEntry::AnnotatedAssistantItem {
+                ts: 1,
+                entry: annotated(agen::Item::tool_call(
+                    "c1",
+                    "TaskCreate",
+                    r#"{"subject":"a","description":"A"}"#,
+                )),
+            })
+            .unwrap(),
+            serde_json::to_value(session_store::LogEntry::AnnotatedAssistantItem {
+                ts: 2,
+                entry: annotated(agen::Item::tool_call(
+                    "c2",
+                    "TaskCreate",
+                    r#"{"subject":"b","description":"B"}"#,
+                )),
+            })
+            .unwrap(),
+            serde_json::to_value(session_store::LogEntry::AnnotatedAssistantItem {
+                ts: 3,
+                entry: annotated(agen::Item::tool_call(
+                    "u1",
+                    "TaskUpdate",
+                    r#"{"taskid":2,"status":"inprogress"}"#,
+                )),
+            })
+            .unwrap(),
         ];
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: assistant_item_entries,
+            session: public_session(assistant_item_entries),
             status: WorkerStatus::Running,
             in_flight: Default::default(),
             internal_workers: Vec::new(),

crates/tui/src/console/mod.rs

@@ -547,7 +547,9 @@ async fn run_e2e_rewind_fixture(
     let mut app = App::new_with_persistent_input_history(worker_name.clone(), &workspace_root);
     app.connected = true;
     app.handle_worker_event(Event::Snapshot {
-        entries: Vec::new(),
+        session: protocol::SessionSnapshot {
+            entries: Vec::new(),
+        },
         status: WorkerStatus::Idle,
         greeting: Greeting {
             worker_name: worker_name.clone(),
@@ -673,7 +675,9 @@ async fn run_e2e_rewind_fixture(
         if let Some(submitted_at) = pending_apply {
             if submitted_at.elapsed() >= apply_delay {
                 app.handle_worker_event(Event::RewindApplied {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     input: vec![Segment::text("rewind-live-refresh")],
                     summary: RewindSummary {
                         truncated_to_entries: 1,
@@ -2023,13 +2027,13 @@ mod tests {
         let mut app = App::new("agent".to_string());
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             status: WorkerStatus::Idle,
             in_flight: Default::default(),
             internal_workers: Vec::new(),
         });
         app.handle_worker_event(Event::RewindApplied {
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             input: vec![Segment::Text {
                 content: "retry this".into(),
             }],
@@ -2050,7 +2054,7 @@ mod tests {
         let mut app = App::new("agent".to_string());
         app.handle_worker_event(Event::Snapshot {
             greeting: test_greeting(),
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             status: WorkerStatus::Idle,
             in_flight: Default::default(),
             internal_workers: Vec::new(),
@@ -2058,7 +2062,7 @@ mod tests {
         type_keys(&mut app, "draft");
 
         app.handle_worker_event(Event::RewindApplied {
-            entries: vec![],
+            session: protocol::SessionSnapshot { entries: vec![] },
             input: vec![Segment::Text {
                 content: "retry this".into(),
             }],

crates/tui/src/dashboard/tests.rs

@@ -849,7 +849,9 @@ async fn ticket_queue_notification_sends_notify_when_socket_available() {
         let mut writer = JsonLineWriter::new(writer);
         writer
             .write(&Event::Snapshot {
-                entries: Vec::new(),
+                session: protocol::SessionSnapshot {
+                    entries: Vec::new(),
+                },
                 greeting: protocol::Greeting {
                     worker_name: "test-orchestrator".to_string(),
                     cwd: temp.path().display().to_string(),
@@ -891,7 +893,9 @@ async fn send_notify_only_can_deliver_weak_notification_without_auto_run() {
         let mut writer = JsonLineWriter::new(writer);
         writer
             .write(&Event::Snapshot {
-                entries: Vec::new(),
+                session: protocol::SessionSnapshot {
+                    entries: Vec::new(),
+                },
                 greeting: protocol::Greeting {
                     worker_name: "yoi".to_string(),
                     cwd: temp.path().display().to_string(),

crates/tui/src/worker_list.rs

@@ -623,6 +623,17 @@ mod tests {
 
     const SOURCE: WorkerVisibilitySource = WorkerVisibilitySource::ResumePicker;
 
+    fn annotated(item: agen::Item) -> session_store::LoggedHistoryEntry {
+        session_store::LoggedHistoryEntry {
+            item: session_store::LoggedItem::from(item),
+            metadata: session_store::LoggedSessionHistoryMetadata {
+                entry_id: session_store::LoggedSessionHistoryEntryId::new(),
+                origin: session_store::LoggedSessionHistoryOrigin::LegacyUnknown,
+                derivation: None,
+            },
+        }
+    }
+
     #[test]
     fn stored_metadata_summary_uses_segment_marker_without_reading_session_log() {
         let dir = tempdir().unwrap();
@@ -910,7 +921,7 @@ mod tests {
                 timestamp_ms: 0,
             }),
             Event::Snapshot {
-                entries: vec![],
+                session: protocol::SessionSnapshot { entries: vec![] },
                 greeting: test_greeting(),
                 status: WorkerStatus::Idle,
                 in_flight: Default::default(),
@@ -1207,7 +1218,7 @@ mod tests {
             .append(
                 session_id,
                 segment_id,
-                &LogEntry::SegmentStart {
+                &LogEntry::AnnotatedSegmentStart {
                     ts,
                     session_id,
                     system_prompt: None,
@@ -1231,9 +1242,10 @@ mod tests {
             .append(
                 session_id,
                 segment_id,
-                &LogEntry::UserInput {
+                &LogEntry::AnnotatedUserInput {
                     ts,
                     segments: vec![protocol::Segment::text(text)],
+                    history: vec![annotated(agen::Item::user_message(text))],
                     extensions: vec![],
                 },
             )

crates/worker-runtime/src/runtime.rs

@@ -1530,7 +1530,9 @@ impl Runtime {
             }
         }
         Ok(protocol::Event::Snapshot {
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             greeting: protocol::Greeting {
                 worker_name: worker_ref.worker_id.to_string(),
                 cwd: String::new(),
@@ -3152,7 +3154,9 @@ mod tests {
             ),
         );
         let snapshot = protocol::Event::Snapshot {
-            entries: Vec::new(),
+            session: protocol::SessionSnapshot {
+                entries: Vec::new(),
+            },
             greeting: protocol::Greeting {
                 worker_name: "parent".to_string(),
                 cwd: "/tmp".to_string(),
@@ -4581,7 +4585,17 @@ mod tests {
         backend.set_worker_snapshot(
             &detail.worker_ref,
             protocol::Event::Snapshot {
-                entries: vec![expected_entry.clone()],
+                session: protocol::SessionSnapshot {
+                    entries: vec![protocol::SessionSnapshotEntry {
+                        entry_id: "restored-log-entry".to_owned(),
+                        timestamp: 1,
+                        provenance: protocol::SessionEntryProvenance::LegacyUnknown,
+                        derived_from: Vec::new(),
+                        data: protocol::SessionSnapshotEntryData::RunError {
+                            message: expected_entry.to_string(),
+                        },
+                    }],
+                },
                 greeting: protocol::Greeting {
                     worker_name: "live-worker".to_string(),
                     cwd: "/tmp/live".to_string(),
@@ -4606,12 +4620,13 @@ mod tests {
             .unwrap();
         match snapshot {
             protocol::Event::Snapshot {
-                entries,
+                session,
                 greeting,
                 status,
                 ..
             } => {
-                assert_eq!(entries, vec![expected_entry]);
+                assert_eq!(session.entries.len(), 1);
+                assert_eq!(session.entries[0].entry_id, "restored-log-entry");
                 assert_eq!(greeting.worker_name, "live-worker");
                 assert_eq!(status, protocol::WorkerStatus::Running);
             }

crates/worker-runtime/src/worker_backend.rs

@@ -67,8 +67,7 @@ const USER_INPUT_COMMIT_TIMEOUT: Duration = Duration::from_secs(9);
 
 fn user_input_has_submission(entry: &LogEntry, submission_id: &str) -> bool {
     let extensions = match entry {
-        LogEntry::UserInput { extensions, .. }
-        | LogEntry::AnnotatedUserInput { extensions, .. } => extensions,
+        LogEntry::AnnotatedUserInput { extensions, .. } => extensions,
         _ => return false,
     };
     extensions.iter().any(|extension| {
@@ -3244,8 +3243,7 @@ mod tests {
         assert!(entries.iter().any(|entry| {
             matches!(
                 entry,
-                LogEntry::UserInput { segments, .. }
-                | LogEntry::AnnotatedUserInput { segments, .. }
+                LogEntry::AnnotatedUserInput { segments, .. }
                     if segments == &vec![Segment::text("start the ticket")]
             )
         }));
@@ -3253,8 +3251,7 @@ mod tests {
             .iter()
             .find_map(|entry| {
                 let extensions = match entry {
-                    LogEntry::UserInput { extensions, .. }
-                    | LogEntry::AnnotatedUserInput { extensions, .. } => extensions,
+                    LogEntry::AnnotatedUserInput { extensions, .. } => extensions,
                     _ => return None,
                 };
                 extensions

crates/worker/src/controller.rs

@@ -84,10 +84,7 @@ impl WorkerHandle {
             (entries, entry_rx, in_flight)
         };
         let event = Event::Snapshot {
-            entries: entries
-                .into_iter()
-                .map(|entry| serde_json::to_value(entry).expect("log entry serializes"))
-                .collect(),
+            session: session_store::public_snapshot::project_current_session_snapshot(&entries),
             greeting: self.shared_state.greeting.clone(),
             status: self.shared_state.get_status(),
             in_flight,
@@ -634,8 +631,8 @@ fn protocol_command_status(status: WorkdirCommandStatus) -> ProtocolCommandStatu
 ///
 /// `Worker::wire_history_persistence` is called separately to wire the
 /// per-item history commit callback so every assistant / tool item
-/// landing in `worker.history` becomes a singular `LogEntry::AssistantItem`
-/// / `ToolResult` commit through the sync writer.
+/// landing in `worker.history` becomes a singular `LogEntry::AnnotatedAssistantItem`
+/// / `AnnotatedToolResult` commit through the sync writer.
 pub(crate) fn wire_event_bridges_on_engine<C, St>(
     worker: &mut Worker<C, St>,
     event_tx: &broadcast::Sender<Event>,
@@ -1320,7 +1317,7 @@ async fn controller_loop<C, St>(
                 }
                 // Stage the run without a speculative user-message echo.
                 // `Worker::run` validates the input, commits
-                // `LogEntry::UserInput`, and the session-log sink turns that
+                // `LogEntry::AnnotatedUserInput`, and the session-log sink turns that
                 // committed entry into the live `Event::UserMessage`. That
                 // keeps every client ordered against `SegmentStart` replay and
                 // makes persisted history the single source of visible user
@@ -1346,7 +1343,7 @@ async fn controller_loop<C, St>(
             Method::Notify { message, auto_run } => {
                 // Client-side live echo is delivered as `Event::SystemItem`
                 // once the interceptor commits the corresponding
-                // `LogEntry::SystemItem` entry — drained out of the
+                // `LogEntry::AnnotatedSystemItem` entry — drained out of the
                 // notify buffer + broadcast through the sink. No
                 // separate echo here.
                 worker.push_notify(message, auto_run);
@@ -1874,28 +1871,16 @@ where
     St: Store,
 {
     match worker.rewind_to(target, expected_head_entries) {
-        Ok(applied) => match applied
-            .entries
-            .into_iter()
-            .map(serde_json::to_value)
-            .collect::<Result<Vec<_>, _>>()
-        {
-            Ok(entries) => {
-                let _ = event_tx.send(Event::RewindApplied {
-                    entries,
-                    input: applied.input,
-                    summary: applied.summary,
-                });
-                true
-            }
-            Err(error) => {
-                let _ = event_tx.send(Event::Error {
-                    code: ErrorCode::Internal,
-                    message: format!("failed to encode rewind snapshot: {error}"),
-                });
-                false
-            }
-        },
+        Ok(applied) => {
+            let session =
+                session_store::public_snapshot::project_current_session_snapshot(&applied.entries);
+            let _ = event_tx.send(Event::RewindApplied {
+                session,
+                input: applied.input,
+                summary: applied.summary,
+            });
+            true
+        }
         Err(err) => {
             let _ = event_tx.send(Event::Error {
                 code: ErrorCode::InvalidRequest,
@@ -2101,7 +2086,9 @@ mod tests {
             let mut writer = JsonLineWriter::new(w);
             writer
                 .write(&Event::Snapshot {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     greeting: protocol::Greeting {
                         worker_name: "parent".into(),
                         cwd: "/tmp".into(),

crates/worker/src/discovery.rs

@@ -1481,7 +1481,9 @@ mod tests {
             let mut writer = JsonLineWriter::new(stream);
             writer
                 .write(&Event::Snapshot {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     greeting: protocol::Greeting {
                         worker_name: "target".into(),
                         cwd: "/tmp".into(),
@@ -1514,7 +1516,9 @@ mod tests {
                 .unwrap();
             writer
                 .write(&Event::Snapshot {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     greeting: protocol::Greeting {
                         worker_name: "target".into(),
                         cwd: "/tmp".into(),
@@ -1603,7 +1607,9 @@ mod tests {
             let mut writer = JsonLineWriter::new(stream);
             writer
                 .write(&Event::Snapshot {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     greeting: protocol::Greeting {
                         worker_name: "target".into(),
                         cwd: "/tmp".into(),
@@ -1627,7 +1633,9 @@ mod tests {
             let mut writer = JsonLineWriter::new(writer_half);
             writer
                 .write(&Event::Snapshot {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     greeting: protocol::Greeting {
                         worker_name: "target".into(),
                         cwd: "/tmp".into(),
@@ -1729,7 +1737,9 @@ mod tests {
                 .unwrap();
             writer
                 .write(&Event::Snapshot {
-                    entries: Vec::new(),
+                    session: protocol::SessionSnapshot {
+                        entries: Vec::new(),
+                    },
                     greeting: protocol::Greeting {
                         worker_name: "alerted".into(),
                         cwd: "/tmp".into(),
@@ -1779,7 +1789,9 @@ mod tests {
                     let mut writer = JsonLineWriter::new(stream);
                     let _ = writer
                         .write(&Event::Snapshot {
-                            entries: Vec::new(),
+                            session: protocol::SessionSnapshot {
+                                entries: Vec::new(),
+                            },
                             greeting: protocol::Greeting {
                                 worker_name: "child-live".into(),
                                 cwd: "/tmp".into(),

crates/worker/src/feature/builtin/flow_transition.rs

@@ -963,9 +963,12 @@ permission = "read"
             .append(
                 session_id,
                 segment_id,
-                &LogEntry::UserInput {
+                &LogEntry::AnnotatedUserInput {
                     ts: 1,
                     extensions: vec![],
+                    history: vec![crate::session_history::test_logged_history_entry(
+                        agen::Item::user_message("verify current Flow conditions"),
+                    )],
                     segments: vec![Segment::Text {
                         content: "verify current Flow conditions".into(),
                     }],

crates/worker/src/feature/builtin/memory_extract.rs

@@ -185,12 +185,9 @@ impl Tool for StageMemoryCandidateTool {
             })?);
         }
         if matches!(params.kind, CandidateKind::Preference)
-            && entries.iter().any(|entry| {
-                !matches!(
-                    entry.origin,
-                    crate::WorkerHistoryProvenance::HumanInput { .. }
-                )
-            })
+            && entries
+                .iter()
+                .any(|entry| !matches!(entry.origin, protocol::SessionEntryProvenance::HumanInput))
         {
             return Err(ToolError::InvalidArgument(
                 "preference candidates require exclusively HumanInput evidence; model, Worker, Flow, backend, derived, and legacy-unknown origins are not preference authority"
@@ -324,10 +321,23 @@ fn evidence_kind(entry: &SessionEntryEvidence) -> EvidenceKind {
     }
 }
 
-fn evidence_origin(origin: &crate::WorkerHistoryProvenance) -> EvidenceOrigin {
-    use crate::WorkerHistoryProvenance as Origin;
-    let mut evidence = EvidenceOrigin {
-        kind: EvidenceOriginKind::LegacyUnknown,
+fn evidence_origin(origin: &protocol::SessionEntryProvenance) -> EvidenceOrigin {
+    use protocol::SessionEntryProvenance as Origin;
+    let kind = match origin {
+        Origin::HumanInput => EvidenceOriginKind::HumanInput,
+        Origin::WorkerInput => EvidenceOriginKind::WorkerInput,
+        Origin::FlowInstruction => EvidenceOriginKind::FlowInstruction,
+        Origin::BackendInstruction => EvidenceOriginKind::BackendInstruction,
+        Origin::ModelOutput => EvidenceOriginKind::ModelOutput,
+        Origin::ToolOutput => EvidenceOriginKind::ToolOutput,
+        Origin::DerivedSummary => EvidenceOriginKind::DerivedSummary,
+        Origin::LegacyUnknown => EvidenceOriginKind::LegacyUnknown,
+    };
+    EvidenceOrigin {
+        kind,
+        // The public SessionSnapshot intentionally excludes account, Worker,
+        // Runtime, and Flow internals. Preserve the authenticated origin class
+        // without inventing missing control-plane identity fields.
         account_id: None,
         workspace_id: None,
         runtime_id: None,
@@ -335,46 +345,7 @@ fn evidence_origin(origin: &crate::WorkerHistoryProvenance) -> EvidenceOrigin {
         flow_selector: None,
         flow_definition_id: None,
         flow_definition_revision: None,
-    };
-    match origin {
-        Origin::HumanInput { account_id } => {
-            evidence.kind = EvidenceOriginKind::HumanInput;
-            evidence.account_id = Some(account_id.clone());
-        }
-        Origin::WorkerInput { actor } => {
-            evidence.kind = EvidenceOriginKind::WorkerInput;
-            evidence.workspace_id = actor.workspace_id.clone();
-            evidence.runtime_id = actor.runtime_id.clone();
-            evidence.worker_id = Some(actor.worker_id.clone());
-        }
-        Origin::FlowInstruction {
-            selector,
-            definition_id,
-            definition_revision,
-            ..
-        } => {
-            evidence.kind = EvidenceOriginKind::FlowInstruction;
-            evidence.flow_selector = Some(selector.clone());
-            evidence.flow_definition_id = Some(definition_id.clone());
-            evidence.flow_definition_revision = Some(*definition_revision);
-        }
-        Origin::BackendInstruction { .. } => evidence.kind = EvidenceOriginKind::BackendInstruction,
-        Origin::ModelOutput { worker } => {
-            evidence.kind = EvidenceOriginKind::ModelOutput;
-            evidence.workspace_id = worker.workspace_id.clone();
-            evidence.runtime_id = worker.runtime_id.clone();
-            evidence.worker_id = Some(worker.worker_id.clone());
-        }
-        Origin::ToolOutput { worker } => {
-            evidence.kind = EvidenceOriginKind::ToolOutput;
-            evidence.workspace_id = worker.workspace_id.clone();
-            evidence.runtime_id = worker.runtime_id.clone();
-            evidence.worker_id = Some(worker.worker_id.clone());
-        }
-        Origin::DerivedSummary => evidence.kind = EvidenceOriginKind::DerivedSummary,
-        Origin::LegacyUnknown => evidence.kind = EvidenceOriginKind::LegacyUnknown,
     }
-    evidence
 }
 
 fn staging_evidence(entry: &SessionEntryEvidence) -> StagingEvidence {
@@ -502,12 +473,10 @@ mod tests {
     }
 
     #[test]
-    fn human_origin_projects_account_authority_into_evidence() {
-        let origin = evidence_origin(&crate::WorkerHistoryProvenance::HumanInput {
-            account_id: "account-1".into(),
-        });
+    fn public_human_origin_preserves_class_without_inventing_account_authority() {
+        let origin = evidence_origin(&protocol::SessionEntryProvenance::HumanInput);
         assert_eq!(origin.kind, EvidenceOriginKind::HumanInput);
-        assert_eq!(origin.account_id.as_deref(), Some("account-1"));
+        assert_eq!(origin.account_id, None);
     }
 
     #[test]

crates/worker/src/feature/builtin/worker_observation.rs

@@ -6,7 +6,7 @@ use agen::tool::{Tool, ToolDefinition, ToolError, ToolMeta, ToolOutput};
 use async_trait::async_trait;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
-use session_store::{LogEntry, collect_state};
+use session_store::LogEntry;
 
 use super::manage_worker::{WORKER_CONTROL_SERVICE_ID, WorkerControlService};
 use crate::feature::{
@@ -61,7 +61,7 @@ pub struct WorkerObservationSubject {
 #[derive(Debug, Clone)]
 pub struct WorkerSessionCapture {
     pub segment_id: String,
-    pub entries: Vec<agen::HistoryEntry<crate::SessionHistoryMetadata>>,
+    pub session: protocol::SessionSnapshot,
 }
 
 impl WorkerSessionCapture {
@@ -69,17 +69,9 @@ impl WorkerSessionCapture {
         segment_id: impl Into<String>,
         log_entries: &[LogEntry],
     ) -> Result<Self, String> {
-        let segment_id = segment_id.into();
-        let state = collect_state(log_entries);
-        let parsed_segment_id = segment_id.parse().unwrap_or_default();
-        let entries = crate::session_history::restore_history_entries(
-            state.session_id.unwrap_or_default(),
-            parsed_segment_id,
-            log_entries,
-        )?;
         Ok(Self {
-            segment_id,
-            entries,
+            segment_id: segment_id.into(),
+            session: session_store::public_snapshot::project_current_session_snapshot(log_entries),
         })
     }
 }
@@ -115,7 +107,7 @@ struct WorkspaceWorkerObservationListResponse {
 #[derive(Debug, Deserialize)]
 struct WorkspaceWorkerObservationCaptureResponse {
     segment_id: String,
-    entries: Vec<serde_json::Value>,
+    session: protocol::SessionSnapshot,
 }
 
 pub struct WorkspaceClientWorkerObservationProvider {
@@ -173,26 +165,9 @@ impl WorkerObservationProvider for WorkspaceClientWorkerObservationProvider {
         let body = workspace_response_body(response)?;
         let response = serde_json::from_str::<WorkspaceWorkerObservationCaptureResponse>(&body)
             .map_err(|error| WorkerObservationError::Unavailable(error.to_string()))?;
-        let entries = response
-            .entries
-            .into_iter()
-            .map(|entry| {
-                serde_json::from_value(entry)
-                    .map_err(|error| WorkerObservationError::Unavailable(error.to_string()))
-            })
-            .collect::<Result<Vec<session_store::LogEntry>, _>>()?;
-        let state = collect_state(&entries);
-        let segment_id = response.segment_id;
-        let parsed_segment_id = segment_id.parse().unwrap_or_default();
-        let typed_entries = crate::session_history::restore_history_entries(
-            state.session_id.unwrap_or_default(),
-            parsed_segment_id,
-            &entries,
-        )
-        .map_err(WorkerObservationError::Unavailable)?;
         Ok(WorkerSessionCapture {
-            segment_id,
-            entries: typed_entries,
+            segment_id: response.segment_id,
+            session: response.session,
         })
     }
 }
@@ -420,16 +395,9 @@ impl WorkerObservationProvider for SpawnedSubWorkerObservationProvider {
             .get_internal(name)
             .ok_or(WorkerObservationError::NotFound)?;
         let entries = record.session.entries();
-        let state = collect_state(&entries);
-        let typed_entries = crate::session_history::restore_history_entries(
-            state.session_id.unwrap_or_default(),
-            Default::default(),
-            &entries,
-        )
-        .map_err(WorkerObservationError::Unavailable)?;
         Ok(WorkerSessionCapture {
             segment_id: format!("subworker:{name}"),
-            entries: typed_entries,
+            session: session_store::public_snapshot::project_current_session_snapshot(&entries),
         })
     }
 }
@@ -699,9 +667,9 @@ async fn latest_view(
         .capture_worker_session(subject)
         .await
         .map_err(tool_error)?;
-    Ok(SessionCapture::from_history_entries(
+    Ok(SessionCapture::from_session_snapshot(
         capture.segment_id,
-        capture.entries,
+        capture.session,
     ))
 }
 
@@ -799,16 +767,43 @@ mod tests {
                 .clone()
                 .into_iter()
                 .enumerate()
-                .map(|(index, item)| {
-                    let mut metadata = crate::SessionHistoryMetadata::legacy_unknown();
-                    metadata.entry_id =
-                        session_store::LoggedSessionHistoryEntryId(format!("fake-{index:08}"));
-                    agen::HistoryEntry::new(item, metadata)
+                .filter_map(|(index, item)| {
+                    let data = match item {
+                        Item::Message { role, content, .. } => {
+                            let role = match role {
+                                Role::User => protocol::SessionMessageRole::User,
+                                Role::Assistant => protocol::SessionMessageRole::Assistant,
+                                Role::System => return None,
+                            };
+                            protocol::SessionSnapshotEntryData::Message {
+                                role,
+                                content: content
+                                    .into_iter()
+                                    .map(|part| match part {
+                                        agen::ContentPart::Text { text } => {
+                                            protocol::SessionContentPart::Text { text }
+                                        }
+                                        agen::ContentPart::Refusal { refusal } => {
+                                            protocol::SessionContentPart::Refusal { refusal }
+                                        }
+                                    })
+                                    .collect(),
+                            }
+                        }
+                        _ => return None,
+                    };
+                    Some(protocol::SessionSnapshotEntry {
+                        entry_id: format!("fake-{index:08}"),
+                        timestamp: index as u64,
+                        provenance: protocol::SessionEntryProvenance::LegacyUnknown,
+                        derived_from: Vec::new(),
+                        data,
+                    })
                 })
                 .collect();
             Ok(WorkerSessionCapture {
                 segment_id: "segment".to_string(),
-                entries,
+                session: protocol::SessionSnapshot { entries },
             })
         }
     }

crates/worker/src/hook.rs

@@ -161,7 +161,7 @@ impl From<HookTurnEndAction> for TurnEndAction {
 ///
 /// Hook code can use this handle only when the Worker host includes it in an
 /// event-specific context. The handle queues typed requests; the host drains the
-/// queue, commits each entry through `LogEntry::SystemItem`, and only then makes
+/// queue, commits each entry through `LogEntry::AnnotatedSystemItem`, and only then makes
 /// the matching system message visible to the model. It deliberately exposes no
 /// raw `agen::Item`, history writer, event sender, `Worker`, `Engine`, or
 /// notification buffer.

crates/worker/src/in_flight.rs

@@ -539,9 +539,9 @@ mod tests {
                 text: "done".into(),
             }],
         };
-        let assistant_entry = LogEntry::AssistantItem {
+        let assistant_entry = LogEntry::AnnotatedAssistantItem {
             ts: 1,
-            item: assistant_item.clone(),
+            entry: crate::session_history::test_logged_history_entry(assistant_item.clone()),
         };
 
         let in_flight_guard = in_flight.snapshot_guard();
@@ -593,9 +593,9 @@ mod tests {
                 text: "done".into(),
             }],
         };
-        let assistant_entry = LogEntry::AssistantItem {
+        let assistant_entry = LogEntry::AnnotatedAssistantItem {
             ts: 1,
-            item: assistant_item.clone(),
+            entry: crate::session_history::test_logged_history_entry(assistant_item.clone()),
         };
 
         in_flight.clear_for_committed_item_then(&assistant_item, || {
@@ -608,7 +608,7 @@ mod tests {
 
         assert!(matches!(
             entries_snapshot.as_slice(),
-            [LogEntry::AssistantItem { item, .. }] if item == &assistant_item
+            [LogEntry::AnnotatedAssistantItem { entry, .. }] if entry.item == assistant_item
         ));
         assert!(in_flight_snapshot.is_empty());
     }

crates/worker/src/internal_worker.rs

@@ -335,7 +335,7 @@ enum InternalWorkerSessionCommand {
 /// task; protocol access is consumed only by the owning parent registry.
 #[derive(Debug, Clone)]
 pub(crate) struct InternalWorkerSessionSnapshot {
-    pub entries: Vec<LogEntry>,
+    pub session: protocol::SessionSnapshot,
     pub status: WorkerStatus,
     pub error: Option<String>,
     pub in_flight: InFlightSnapshot,
@@ -402,7 +402,7 @@ impl InternalWorkerSessionHandle {
             (entries, snapshot_from_guard(&guard))
         };
         InternalWorkerSessionSnapshot {
-            entries,
+            session: session_store::public_snapshot::project_current_session_snapshot(&entries),
             status: match self.status() {
                 InternalWorkerSessionStatus::Running => WorkerStatus::Running,
                 InternalWorkerSessionStatus::Paused => WorkerStatus::Paused,

crates/worker/src/ipc/interceptor.rs

@@ -60,7 +60,7 @@ pub(crate) struct WorkerInterceptor {
     pending_notifies: NotifyBuffer,
     /// Submit-scoped stash of resolver-produced typed system items.
     /// Drained inside `on_prompt_submit`, committed as
-    /// `LogEntry::SystemItem` entries through `log_writer`, and
+    /// `LogEntry::AnnotatedSystemItem` entries through `log_writer`, and
     /// returned to the worker as `Item::system_message` via
     /// `PromptAction::ContinueWith`. Populated by `Worker::run`
     /// immediately before handing off to the worker.
@@ -71,7 +71,7 @@ pub(crate) struct WorkerInterceptor {
     /// Workspace scope associated with Prompt projection provenance.
     prompt_workspace_id: Option<String>,
     /// Type-erased commit handle. The interceptor uses it to commit
-    /// `LogEntry::SystemItem` entries directly (sync) before
+    /// `LogEntry::AnnotatedSystemItem` entries directly (sync) before
     /// returning the corresponding `Item::system_message`s up to the
     /// worker. `None` in tests / `Worker::new` paths where no writer is
     /// attached.
@@ -142,7 +142,7 @@ impl WorkerInterceptor {
         self
     }
 
-    /// Commit each `SystemItem` as its own `LogEntry::SystemItem`
+    /// Commit each `SystemItem` as its own `LogEntry::AnnotatedSystemItem`
     /// entry through the attached writer (no-op when no writer is
     /// wired). Sync — writes complete before the matching
     /// `Item::system_message`s reach the worker via
@@ -540,7 +540,6 @@ mod tests {
             entry: session_store::LogEntry,
         ) -> Result<(), session_store::StoreError> {
             let item = match entry {
-                session_store::LogEntry::SystemItem { item, .. } => Some(item),
                 session_store::LogEntry::AnnotatedSystemItem { entry, .. } => Some(entry.item),
                 _ => None,
             };

crates/worker/src/ipc/notify_buffer.rs

@@ -5,7 +5,7 @@
 //! `WorkerInterceptor::pending_history_appends`, which the Engine calls
 //! at the head of each turn loop iteration. The drain renders each
 //! pending entry into a typed `SystemItem` (with the `notify_wrapper`
-//! prompt applied), commits a `LogEntry::SystemItem` per entry through
+//! prompt applied), commits a `LogEntry::AnnotatedSystemItem` per entry through
 //! the session-log sink, and returns the corresponding
 //! `Item::system_message`s for the worker to append to its
 //! persistent history.

crates/worker/src/ipc/protocol_session.rs

@@ -29,17 +29,12 @@ pub fn subscribe_worker_protocol_session(handle: &WorkerHandle) -> WorkerProtoco
 
 pub fn live_log_entry_event(entry: LogEntry) -> Option<Event> {
     match entry {
-        entry @ (LogEntry::SegmentStart { .. } | LogEntry::AnnotatedSegmentStart { .. }) => {
-            let value = serde_json::to_value(&entry).expect("LogEntry is Serialize");
-            Some(Event::SegmentRotated { entry: value })
-        }
-        LogEntry::UserInput { segments, .. } | LogEntry::AnnotatedUserInput { segments, .. } => {
-            Some(Event::UserMessage { segments })
-        }
-        LogEntry::SystemItem { item, .. } => {
-            let value = serde_json::to_value(&item).expect("SystemItem is Serialize");
-            Some(Event::SystemItem { item: value })
+        entry @ LogEntry::AnnotatedSegmentStart { .. } => {
+            let session =
+                session_store::public_snapshot::project_current_session_snapshot(&[entry]);
+            Some(Event::SegmentRotated { session })
         }
+        LogEntry::AnnotatedUserInput { segments, .. } => Some(Event::UserMessage { segments }),
         LogEntry::AnnotatedSystemItem { entry, .. } => {
             let value = serde_json::to_value(&entry.item).expect("SystemItem is Serialize");
             Some(Event::SystemItem { item: value })
@@ -88,9 +83,12 @@ mod tests {
     #[test]
     fn user_input_log_entry_maps_to_user_message_event() {
         let segments = vec![protocol::Segment::text("hello from log")];
-        let event = live_log_entry_event(LogEntry::UserInput {
+        let event = live_log_entry_event(LogEntry::AnnotatedUserInput {
             ts: session_store::segment_log::now_millis(),
             extensions: vec![],
+            history: vec![crate::session_history::test_logged_history_entry(
+                agen::Item::user_message("hello from log"),
+            )],
             segments: segments.clone(),
         })
         .expect("UserInput must be live-relevant");

crates/worker/src/ipc/server.rs

@@ -77,7 +77,7 @@ async fn handle_connection(stream: tokio::net::UnixStream, handle: WorkerHandle)
     let mut writer = JsonLineWriter::new(writer);
 
     // Hold the in-flight stream lock while taking the session-log mirror
-    // snapshot. `LogEntry::AssistantItem` is mirror-only for live clients,
+    // snapshot. `LogEntry::AnnotatedAssistantItem` is mirror-only for live clients,
     // so a finalized assistant block must be observed either as an already
     // committed entry or as the still-present in-flight block. This lock
     // order matches `append_entry` (in-flight clear before sink publish) and

crates/worker/src/segment_log_sink.rs

@@ -50,7 +50,7 @@ struct SinkInner {
     /// Broadcast channel for live entry updates. The same `Sender`
     /// survives session swaps so existing subscribers keep their
     /// receiver — they observe the swap as a freshly broadcast
-    /// `LogEntry::SegmentStart` and reset their view accordingly.
+    /// `LogEntry::AnnotatedSegmentStart` and reset their view accordingly.
     broadcast_tx: broadcast::Sender<LogEntry>,
 }
 
@@ -89,9 +89,9 @@ impl SegmentLogSink {
     ///
     /// Live broadcast fires for committed session-log entries that
     /// socket clients must see in log order:
-    ///   - `LogEntry::SegmentStart` → `Event::SegmentRotated` on the wire.
-    ///   - `LogEntry::UserInput`    → `Event::UserMessage`.
-    ///   - `LogEntry::SystemItem`   → `Event::SystemItem`.
+    ///   - `LogEntry::AnnotatedSegmentStart` → `Event::SegmentRotated` on the wire.
+    ///   - `LogEntry::AnnotatedUserInput`    → `Event::UserMessage`.
+    ///   - `LogEntry::AnnotatedSystemItem`   → `Event::SystemItem`.
     ///   - `LogEntry::Invoke`       → `Event::InvokeStart`.
     /// Everything else (AssistantItem, ToolResult, TurnEnd,
     /// RunCompleted, RunErrored, PausedTurnAbandoned, LlmUsage, Extension,
@@ -120,11 +120,8 @@ impl SegmentLogSink {
     fn is_live_relevant(entry: &LogEntry) -> bool {
         matches!(
             entry,
-            LogEntry::SegmentStart { .. }
-                | LogEntry::AnnotatedSegmentStart { .. }
-                | LogEntry::UserInput { .. }
+            LogEntry::AnnotatedSegmentStart { .. }
                 | LogEntry::AnnotatedUserInput { .. }
-                | LogEntry::SystemItem { .. }
                 | LogEntry::AnnotatedSystemItem { .. }
                 | LogEntry::Invoke { .. }
         )
@@ -132,7 +129,7 @@ impl SegmentLogSink {
 
     /// Atomically swap the mirror to `[initial]` and broadcast the new
     /// session-start entry. Used during compaction / fork: the new
-    /// `LogEntry::SegmentStart` is the first entry of the replacement
+    /// `LogEntry::AnnotatedSegmentStart` is the first entry of the replacement
     /// session, and existing subscribers transition by replaying it
     /// like any other live entry.
     ///
@@ -234,7 +231,7 @@ mod tests {
     use session_store::segment_log::now_millis;
 
     fn session_start() -> LogEntry {
-        LogEntry::SegmentStart {
+        LogEntry::AnnotatedSegmentStart {
             ts: now_millis(),
             session_id: uuid::Uuid::nil(),
             system_prompt: None,
@@ -253,9 +250,12 @@ mod tests {
     }
 
     fn user_input(text: &str) -> LogEntry {
-        LogEntry::UserInput {
+        LogEntry::AnnotatedUserInput {
             ts: now_millis(),
             extensions: vec![],
+            history: vec![crate::session_history::test_logged_history_entry(
+                agen::Item::user_message(text),
+            )],
             segments: vec![protocol::Segment::Text {
                 content: text.to_owned(),
             }],
@@ -270,7 +270,10 @@ mod tests {
 
         let (snapshot, mut rx) = sink.subscribe_with_snapshot();
         assert_eq!(snapshot.len(), 2);
-        assert!(matches!(snapshot[0], LogEntry::SegmentStart { .. }));
+        assert!(matches!(
+            snapshot[0],
+            LogEntry::AnnotatedSegmentStart { .. }
+        ));
         assert!(matches!(
             snapshot[1],
             LogEntry::TurnEnd { turn_count: 1, .. }
@@ -279,13 +282,15 @@ mod tests {
     }
 
     fn notification_entry(text: &str) -> LogEntry {
-        LogEntry::SystemItem {
+        LogEntry::AnnotatedSystemItem {
             ts: now_millis(),
-            item: session_store::SystemItem::Notification {
-                message: text.to_owned(),
-                body: format!("[Notification] {text}"),
-                prompt_provenance: None,
-            },
+            entry: crate::session_history::test_logged_system_entry(
+                session_store::SystemItem::Notification {
+                    message: text.to_owned(),
+                    body: format!("[Notification] {text}"),
+                    prompt_provenance: None,
+                },
+            ),
         }
     }
 
@@ -305,7 +310,7 @@ mod tests {
         // for Event::UserMessage.
         sink.publish(user_input("hi from log"));
         match rx.try_recv() {
-            Ok(LogEntry::UserInput { segments, .. }) => {
+            Ok(LogEntry::AnnotatedUserInput { segments, .. }) => {
                 assert_eq!(segments.len(), 1);
             }
             other => panic!("expected UserInput, got {other:?}"),
@@ -314,7 +319,7 @@ mod tests {
         // SystemItem is live-relevant.
         sink.publish(notification_entry("hi"));
         match rx.try_recv() {
-            Ok(LogEntry::SystemItem { .. }) => {}
+            Ok(LogEntry::AnnotatedSystemItem { .. }) => {}
             other => panic!("expected SystemItem, got {other:?}"),
         }
 
@@ -332,7 +337,7 @@ mod tests {
 
         assert_eq!(snapshot.len(), 1);
         match rx.try_recv() {
-            Ok(LogEntry::SystemItem { .. }) => {}
+            Ok(LogEntry::AnnotatedSystemItem { .. }) => {}
             other => panic!("unexpected: {other:?}"),
         }
         assert!(rx.try_recv().is_err());
@@ -348,13 +353,16 @@ mod tests {
         sink.reset_with_initial(session_start());
 
         match rx.try_recv() {
-            Ok(LogEntry::SegmentStart { .. }) => {}
+            Ok(LogEntry::AnnotatedSegmentStart { .. }) => {}
             other => panic!("expected SegmentStart broadcast, got {other:?}"),
         }
 
         let (post_snapshot, _) = sink.subscribe_with_snapshot();
         assert_eq!(post_snapshot.len(), 1);
-        assert!(matches!(post_snapshot[0], LogEntry::SegmentStart { .. }));
+        assert!(matches!(
+            post_snapshot[0],
+            LogEntry::AnnotatedSegmentStart { .. }
+        ));
     }
 
     #[test]

crates/worker/src/session_capture.rs

@@ -8,6 +8,10 @@ use std::sync::Arc;
 
 use crate::session_history::{SessionHistoryMetadata, WorkerHistoryProvenance};
 use agen::{HistoryEntry, Item, Role};
+use protocol::{
+    SessionContentPart, SessionEntryProvenance, SessionMessageRole, SessionSnapshot,
+    SessionSnapshotEntryData,
+};
 use serde::{Deserialize, Serialize};
 
 const DEFAULT_SEARCH_LIMIT: usize = 20;
@@ -105,7 +109,7 @@ impl ToolPart {
 #[derive(Debug, Clone)]
 pub(crate) struct OverviewItem {
     pub id: SessionEntryRef,
-    pub origin: WorkerHistoryProvenance,
+    pub origin: SessionEntryProvenance,
     pub entry_range: [u64; 2],
     pub kind: ReferenceKind,
     pub label: String,
@@ -116,7 +120,7 @@ pub(crate) struct OverviewItem {
 #[derive(Debug, Clone)]
 pub(crate) struct ReferenceEntry {
     pub id: SessionEntryRef,
-    pub origin: WorkerHistoryProvenance,
+    pub origin: SessionEntryProvenance,
     pub entry_range: [u64; 2],
     pub kind: ReferenceKind,
     pub tool_part: Option<ToolPart>,
@@ -142,7 +146,7 @@ pub(crate) struct SearchOptions {
 #[derive(Debug, Clone)]
 pub(crate) struct SearchHit {
     pub id: SessionEntryRef,
-    pub origin: WorkerHistoryProvenance,
+    pub origin: SessionEntryProvenance,
     pub kind: ReferenceKind,
     pub tool_part: Option<ToolPart>,
     pub tool_name: Option<String>,
@@ -188,7 +192,7 @@ impl Default for ReadOptions {
 #[derive(Debug, Clone)]
 pub(crate) struct ReadEntry {
     pub id: SessionEntryRef,
-    pub origin: WorkerHistoryProvenance,
+    pub origin: SessionEntryProvenance,
     pub kind: ReferenceKind,
     pub tool_part: Option<ToolPart>,
     pub tool_name: Option<String>,
@@ -207,7 +211,7 @@ pub(crate) struct ReadResult {
 pub(crate) struct SessionEntryEvidence {
     pub segment_id: String,
     pub entry_ref: SessionEntryRef,
-    pub origin: WorkerHistoryProvenance,
+    pub origin: SessionEntryProvenance,
     pub entry_range: [u64; 2],
     pub kind: ReferenceKind,
     pub tool_part: Option<ToolPart>,
@@ -216,35 +220,116 @@ pub(crate) struct SessionEntryEvidence {
     pub excerpt: String,
 }
 
+#[derive(Debug, Clone)]
+struct CapturedHistoryEntry {
+    item: Item,
+    entry_id: session_store::LoggedSessionHistoryEntryId,
+    origin: SessionEntryProvenance,
+}
+
 #[derive(Debug, Clone)]
 pub(crate) struct SessionCapture {
     segment_id: String,
-    entries: Arc<Vec<HistoryEntry<SessionHistoryMetadata>>>,
+    entries: Arc<Vec<CapturedHistoryEntry>>,
     overview: Vec<OverviewItem>,
     index: Vec<ReferenceEntry>,
 }
 
 impl SessionCapture {
+    pub(crate) fn from_session_snapshot(
+        segment_id: impl Into<String>,
+        snapshot: SessionSnapshot,
+    ) -> Self {
+        let entries = snapshot
+            .entries
+            .into_iter()
+            .filter_map(|entry| {
+                let item = match entry.data {
+                    SessionSnapshotEntryData::UserInput { segments } => {
+                        Item::user_message(protocol::Segment::flatten_to_text(&segments))
+                    }
+                    SessionSnapshotEntryData::Message { role, content } => {
+                        let role = match role {
+                            SessionMessageRole::User => Role::User,
+                            SessionMessageRole::Assistant => Role::Assistant,
+                        };
+                        Item::Message {
+                            id: None,
+                            role,
+                            content: content
+                                .into_iter()
+                                .map(|part| match part {
+                                    SessionContentPart::Text { text } => {
+                                        agen::ContentPart::Text { text }
+                                    }
+                                    SessionContentPart::Refusal { refusal } => {
+                                        agen::ContentPart::Refusal { refusal }
+                                    }
+                                })
+                                .collect(),
+                            status: None,
+                        }
+                    }
+                    SessionSnapshotEntryData::ToolCall {
+                        call_id,
+                        name,
+                        arguments,
+                    } => Item::tool_call(call_id, name, arguments),
+                    SessionSnapshotEntryData::ToolResult {
+                        call_id,
+                        summary,
+                        content,
+                        is_error,
+                        attachments: _,
+                    } => Item::tool_result_item(call_id, summary, content, is_error),
+                    // Observation deliberately excludes system items and
+                    // controller errors from model-visible session evidence.
+                    SessionSnapshotEntryData::SystemItem { .. }
+                    | SessionSnapshotEntryData::RunError { .. } => return None,
+                };
+                Some(CapturedHistoryEntry {
+                    item,
+                    entry_id: session_store::LoggedSessionHistoryEntryId(entry.entry_id),
+                    origin: entry.provenance,
+                })
+            })
+            .collect();
+        Self::from_captured_entries(segment_id, entries)
+    }
+
     pub(crate) fn new(segment_id: impl Into<String>, items: Vec<Item>) -> Self {
         let entries = items
             .into_iter()
             .enumerate()
-            .map(|(index, item)| {
-                let mut metadata = SessionHistoryMetadata::legacy_unknown();
-                metadata.entry_id =
-                    session_store::LoggedSessionHistoryEntryId(format!("{index:08}"));
-                HistoryEntry::new(item, metadata)
+            .map(|(index, item)| CapturedHistoryEntry {
+                item,
+                entry_id: session_store::LoggedSessionHistoryEntryId(format!("{index:08}")),
+                origin: SessionEntryProvenance::LegacyUnknown,
             })
             .collect();
-        Self::from_history_entries(segment_id, entries)
+        Self::from_captured_entries(segment_id, entries)
     }
 
     pub(crate) fn from_history_entries(
         segment_id: impl Into<String>,
         entries: Vec<HistoryEntry<SessionHistoryMetadata>>,
+    ) -> Self {
+        let entries = entries
+            .into_iter()
+            .map(|entry| CapturedHistoryEntry {
+                item: entry.item,
+                entry_id: entry.annotation.entry_id,
+                origin: public_provenance(&entry.annotation.origin),
+            })
+            .collect();
+        Self::from_captured_entries(segment_id, entries)
+    }
+
+    fn from_captured_entries(
+        segment_id: impl Into<String>,
+        entries: Vec<CapturedHistoryEntry>,
     ) -> Self {
         let segment_id = segment_id.into();
-        let entries = Arc::new(entries);
         let mut overview = Vec::new();
         let mut index = Vec::new();
 
@@ -253,7 +338,7 @@ impl SessionCapture {
             let entry_range = [idx as u64, idx as u64];
             match item {
                 Item::Message { role, content, .. } => {
-                    let Some(kind) = message_reference_kind(&entry.annotation.origin, role) else {
+                    let Some(kind) = message_reference_kind(&entry.origin, role) else {
                         continue;
                     };
                     let text = content
@@ -263,10 +348,10 @@ impl SessionCapture {
                         .join("");
                     let label = format!("{} message", kind.as_str());
                     let summary = truncate_chars(&text, 240);
-                    let id = SessionEntryRef::from_history_entry_id(&entry.annotation.entry_id);
+                    let id = SessionEntryRef::from_history_entry_id(&entry.entry_id);
                     index.push(ReferenceEntry {
                         id: id.clone(),
-                        origin: entry.annotation.origin.clone(),
+                        origin: entry.origin.clone(),
                         entry_range,
                         kind,
                         tool_part: None,
@@ -278,7 +363,7 @@ impl SessionCapture {
                     if matches!(kind, ReferenceKind::User | ReferenceKind::Assistant) {
                         overview.push(OverviewItem {
                             id: id.clone(),
-                            origin: entry.annotation.origin.clone(),
+                            origin: entry.origin.clone(),
                             entry_range,
                             kind,
                             label,
@@ -292,8 +377,8 @@ impl SessionCapture {
                 } => {
                     let text = format!("{name}\n{arguments}");
                     index.push(ReferenceEntry {
-                        id: SessionEntryRef::from_history_entry_id(&entry.annotation.entry_id),
-                        origin: entry.annotation.origin.clone(),
+                        id: SessionEntryRef::from_history_entry_id(&entry.entry_id),
+                        origin: entry.origin.clone(),
                         entry_range,
                         kind: ReferenceKind::Tool,
                         tool_part: Some(ToolPart::Input),
@@ -319,8 +404,8 @@ impl SessionCapture {
                         content.as_deref().unwrap_or_default(),
                     );
                     index.push(ReferenceEntry {
-                        id: SessionEntryRef::from_history_entry_id(&entry.annotation.entry_id),
-                        origin: entry.annotation.origin.clone(),
+                        id: SessionEntryRef::from_history_entry_id(&entry.entry_id),
+                        origin: entry.origin.clone(),
                         entry_range,
                         kind: ReferenceKind::Tool,
                         tool_part: Some(ToolPart::Output),
@@ -360,7 +445,7 @@ impl SessionCapture {
 
         Self {
             segment_id,
-            entries,
+            entries: Arc::new(entries),
             overview,
             index,
         }
@@ -543,25 +628,41 @@ impl SessionCapture {
     }
 }
 
+fn public_provenance(origin: &WorkerHistoryProvenance) -> SessionEntryProvenance {
+    match origin {
+        WorkerHistoryProvenance::HumanInput { .. } => SessionEntryProvenance::HumanInput,
+        WorkerHistoryProvenance::WorkerInput { .. } => SessionEntryProvenance::WorkerInput,
+        WorkerHistoryProvenance::FlowInstruction { .. } => SessionEntryProvenance::FlowInstruction,
+        WorkerHistoryProvenance::BackendInstruction { .. } => {
+            SessionEntryProvenance::BackendInstruction
+        }
+        WorkerHistoryProvenance::ModelOutput { .. } => SessionEntryProvenance::ModelOutput,
+        WorkerHistoryProvenance::ToolOutput { .. } => SessionEntryProvenance::ToolOutput,
+        WorkerHistoryProvenance::DerivedSummary => SessionEntryProvenance::DerivedSummary,
+        WorkerHistoryProvenance::LegacyUnknown => SessionEntryProvenance::LegacyUnknown,
+    }
+}
+
 fn message_reference_kind(
-    origin: &WorkerHistoryProvenance,
+    origin: &SessionEntryProvenance,
     provider_role: &Role,
 ) -> Option<ReferenceKind> {
     match origin {
-        WorkerHistoryProvenance::HumanInput { .. }
-        | WorkerHistoryProvenance::WorkerInput { .. } => Some(ReferenceKind::User),
-        WorkerHistoryProvenance::ModelOutput { .. } => Some(ReferenceKind::Assistant),
-        WorkerHistoryProvenance::ToolOutput { .. } => Some(ReferenceKind::Tool),
-        WorkerHistoryProvenance::LegacyUnknown => match provider_role {
+        SessionEntryProvenance::HumanInput | SessionEntryProvenance::WorkerInput => {
+            Some(ReferenceKind::User)
+        }
+        SessionEntryProvenance::ModelOutput => Some(ReferenceKind::Assistant),
+        SessionEntryProvenance::ToolOutput => Some(ReferenceKind::Tool),
+        SessionEntryProvenance::LegacyUnknown => match provider_role {
             Role::User => Some(ReferenceKind::User),
             Role::Assistant => Some(ReferenceKind::Assistant),
             Role::System => None,
         },
         // Flow/backend/system content remains out of the observation surface
         // even when represented with a provider user/system role.
-        WorkerHistoryProvenance::FlowInstruction { .. }
-        | WorkerHistoryProvenance::BackendInstruction { .. }
-        | WorkerHistoryProvenance::DerivedSummary => None,
+        SessionEntryProvenance::FlowInstruction
+        | SessionEntryProvenance::BackendInstruction
+        | SessionEntryProvenance::DerivedSummary => None,
     }
 }
 
@@ -658,13 +759,13 @@ mod tests {
         assert_eq!(overview.len(), 1);
         assert!(matches!(
             overview[0].origin,
-            WorkerHistoryProvenance::HumanInput { .. }
+            SessionEntryProvenance::HumanInput
         ));
         let evidence = capture.evidence_for(overview[0].id.as_str()).unwrap();
         assert!(evidence.excerpt.ends_with("remember my preference"));
         assert!(matches!(
             evidence.origin,
-            WorkerHistoryProvenance::HumanInput { .. }
+            SessionEntryProvenance::HumanInput
         ));
     }
 

crates/worker/src/session_history.rs

@@ -5,7 +5,6 @@
 //! retained only as explicit `LegacyUnknown` entries.
 
 use agen::{HistoryEntry, Item};
-use protocol::Segment;
 use session_store::{
     LogEntry, LoggedHistoryDerivation, LoggedHistoryEntry, LoggedSessionHistoryEntryId,
     LoggedSessionHistoryMetadata, LoggedSessionHistoryOrigin, LoggedWorkerSubject, SegmentId,
@@ -18,6 +17,32 @@ pub type WorkerHistoryProvenance = LoggedSessionHistoryOrigin;
 pub type SessionHistoryDerivation = LoggedHistoryDerivation;
 pub type WorkerSubjectSnapshot = LoggedWorkerSubject;
 
+#[cfg(test)]
+pub(crate) fn test_logged_history_entry(item: impl Into<Item>) -> LoggedHistoryEntry {
+    LoggedHistoryEntry {
+        item: session_store::LoggedItem::from(item.into()),
+        metadata: LoggedSessionHistoryMetadata {
+            entry_id: LoggedSessionHistoryEntryId::new(),
+            origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+            derivation: None,
+        },
+    }
+}
+
+#[cfg(test)]
+pub(crate) fn test_logged_system_entry(
+    item: session_store::SystemItem,
+) -> session_store::LoggedSystemHistoryEntry {
+    session_store::LoggedSystemHistoryEntry {
+        item,
+        metadata: LoggedSessionHistoryMetadata {
+            entry_id: LoggedSessionHistoryEntryId::new(),
+            origin: LoggedSessionHistoryOrigin::LegacyUnknown,
+            derivation: None,
+        },
+    }
+}
+
 pub(crate) fn worker_subject(session_id: SessionId) -> WorkerSubjectSnapshot {
     WorkerSubjectSnapshot {
         workspace_id: None,
@@ -53,10 +78,6 @@ pub(crate) fn to_logged_history_entry(
     }
 }
 
-fn legacy_entry(item: Item) -> HistoryEntry<SessionHistoryMetadata> {
-    HistoryEntry::new(item, SessionHistoryMetadata::legacy_unknown())
-}
-
 fn from_logged(entry: &LoggedHistoryEntry) -> HistoryEntry<SessionHistoryMetadata> {
     HistoryEntry::new(Item::from(entry.item.clone()), entry.metadata.clone())
 }
@@ -74,32 +95,15 @@ pub(crate) fn restore_history_entries(
             LogEntry::AnnotatedSegmentStart { history: seed, .. } => {
                 history = seed.iter().map(from_logged).collect();
             }
-            LogEntry::SegmentStart { history: seed, .. } => {
-                history = seed
-                    .iter()
-                    .cloned()
-                    .map(Item::from)
-                    .map(legacy_entry)
-                    .collect();
-            }
             LogEntry::AnnotatedUserInput { history: input, .. } => {
                 history.extend(input.iter().map(from_logged))
             }
-            LogEntry::UserInput { segments, .. } => history.push(legacy_entry(Item::user_message(
-                Segment::flatten_to_text(segments),
-            ))),
             LogEntry::AnnotatedAssistantItem { entry, .. }
             | LogEntry::AnnotatedToolResult { entry, .. } => history.push(from_logged(entry)),
-            LogEntry::AssistantItem { item, .. } | LogEntry::ToolResult { item, .. } => {
-                history.push(legacy_entry(Item::from(item.clone())));
-            }
             LogEntry::AnnotatedSystemItem { entry, .. } => history.push(HistoryEntry::new(
                 entry.item.to_history_item(),
                 entry.metadata.clone(),
             )),
-            LogEntry::SystemItem { item, .. } => {
-                history.push(legacy_entry(item.to_history_item()));
-            }
             _ => {}
         }
     }
@@ -110,23 +114,9 @@ pub(crate) fn restore_history_entries(
 mod tests {
     use super::*;
     use agen::llm_client::RequestConfig;
+    use protocol::Segment;
     use session_store::LogEntry;
 
-    #[test]
-    fn legacy_user_role_is_not_inferred_as_human_authority() {
-        let entries = vec![LogEntry::UserInput {
-            ts: 1,
-            segments: vec![Segment::text("legacy")],
-            extensions: Vec::new(),
-        }];
-        let restored =
-            restore_history_entries(SessionId::now_v7(), SegmentId::now_v7(), &entries).unwrap();
-        assert!(matches!(
-            restored[0].annotation.origin,
-            WorkerHistoryProvenance::LegacyUnknown
-        ));
-    }
-
     #[test]
     fn typed_flow_and_unknown_caller_input_round_trip_without_role_inference() {
         let session_id = SessionId::now_v7();

crates/worker/src/spawn/comm_tools.rs

@@ -278,7 +278,21 @@ mod tests {
 
     fn snapshot(entries: Vec<serde_json::Value>) -> Event {
         Event::Snapshot {
-            entries,
+            session: protocol::SessionSnapshot {
+                entries: entries
+                    .into_iter()
+                    .enumerate()
+                    .map(|(index, value)| protocol::SessionSnapshotEntry {
+                        entry_id: format!("test-{index}"),
+                        timestamp: index as u64,
+                        provenance: protocol::SessionEntryProvenance::LegacyUnknown,
+                        derived_from: Vec::new(),
+                        data: protocol::SessionSnapshotEntryData::RunError {
+                            message: value.to_string(),
+                        },
+                    })
+                    .collect(),
+            },
             greeting: Greeting {
                 worker_name: "server".into(),
                 cwd: "/tmp".into(),

crates/worker/src/spawn/registry.rs

@@ -112,8 +112,12 @@ impl InternalSpawnedWorkerRecord {
     fn stop_summary(&self) -> SubWorkerStopSummary {
         let mut counts = BTreeMap::<String, u64>::new();
         for entry in self.session.entries() {
-            if let session_store::LogEntry::AssistantItem {
-                item: LoggedItem::ToolCall { name, .. },
+            if let session_store::LogEntry::AnnotatedAssistantItem {
+                entry:
+                    session_store::LoggedHistoryEntry {
+                        item: LoggedItem::ToolCall { name, .. },
+                        ..
+                    },
                 ..
             } = entry
             {
@@ -806,11 +810,7 @@ fn internal_worker_snapshot(
     InternalWorkerSnapshot {
         worker,
         revision,
-        entries: snapshot
-            .entries
-            .into_iter()
-            .filter_map(|entry| serde_json::to_value(entry).ok())
-            .collect(),
+        session: snapshot.session,
         status: snapshot.status,
         error: snapshot.error,
         in_flight: snapshot.in_flight,
@@ -1028,11 +1028,16 @@ mod tests {
                     && worker.parent_session_id.as_deref() == Some("parent-session")
                     && matches!(*event, Event::TextDone { ref text } if text == "answer")
         ));
-        record.session.publish_test_entry(LogEntry::UserInput {
-            ts: 1,
-            segments: vec![protocol::Segment::text("question")],
-            extensions: Vec::new(),
-        });
+        record
+            .session
+            .publish_test_entry(LogEntry::AnnotatedUserInput {
+                ts: 1,
+                segments: vec![protocol::Segment::text("question")],
+                history: vec![crate::session_history::test_logged_history_entry(
+                    agen::Item::user_message("question"),
+                )],
+                extensions: Vec::new(),
+            });
         let committed = tokio::time::timeout(Duration::from_secs(1), parent_rx.recv())
             .await
             .unwrap()
@@ -1045,7 +1050,7 @@ mod tests {
         let snapshots = registry.internal_worker_snapshots();
         assert_eq!(snapshots.len(), 1);
         assert_eq!(snapshots[0].revision, 2);
-        assert_eq!(snapshots[0].entries.len(), 1);
+        assert_eq!(snapshots[0].session.entries.len(), 1);
 
         record.session.emit_test_text_delta("partial");
         let streamed = tokio::time::timeout(Duration::from_secs(1), parent_rx.recv())
@@ -1163,14 +1168,18 @@ mod tests {
         let (mut record, _events) = record("child", InternalWorkerVisibility::ParentClient).await;
         record.change_tracker = Some(tracker);
         for (index, name) in ["Read", "Read", "Grep"].into_iter().enumerate() {
-            record.session.publish_test_entry(LogEntry::AssistantItem {
-                ts: index as u64,
-                item: LoggedItem::ToolCall {
-                    call_id: format!("call-{index}"),
-                    name: name.to_string(),
-                    arguments: "{}".to_string(),
-                },
-            });
+            record
+                .session
+                .publish_test_entry(LogEntry::AnnotatedAssistantItem {
+                    ts: index as u64,
+                    entry: crate::session_history::test_logged_history_entry(
+                        LoggedItem::ToolCall {
+                            call_id: format!("call-{index}"),
+                            name: name.to_string(),
+                            arguments: "{}".to_string(),
+                        },
+                    ),
+                });
         }
         registry.start_protocol_forwarding(record.clone());
         install_record(&registry, record);

crates/worker/src/spawn/tool.rs

@@ -960,9 +960,7 @@ mod tests {
 
     use crate::WorkspaceId;
     use agen::llm_client::event::{Event as LlmEvent, ResponseStatus, StatusEvent};
-    use agen::llm_client::types::ContentPart;
     use agen::llm_client::{ClientError, LlmClient, Request};
-    use agen::{Item, Role};
     use async_trait::async_trait;
     use futures::Stream;
     use manifest::{AuthRef, ModelManifest, SchemeKind, WorkerManifest};
@@ -1252,9 +1250,11 @@ extract_threshold = 4000
         )
         .await
         .unwrap();
-        assert!(first_capture.entries.iter().map(|entry| &entry.item).any(|item| {
-            matches!(item, Item::Message { role: Role::Assistant, content, .. } if content.iter().any(|part| matches!(part, ContentPart::Text { text } if text.contains("reviewed"))))
-        }));
+        assert!(
+            serde_json::to_string(&first_capture.session)
+                .unwrap()
+                .contains("reviewed")
+        );
 
         let send = (crate::spawn::comm_tools::sub_worker_send_tool(registry.clone()))().1;
         send.execute(
@@ -1274,7 +1274,7 @@ extract_threshold = 4000
         )
         .await
         .unwrap();
-        assert!(latest_capture.entries.len() > first_capture.entries.len());
+        assert!(latest_capture.session.entries.len() > first_capture.session.entries.len());
 
         fail_requests.store(true, Ordering::SeqCst);
         send.execute(

crates/worker/src/worker.rs

@@ -900,7 +900,6 @@ where
         self.state.increment_entries();
         if let Some(in_flight) = &self.in_flight {
             let committed_item = match &entry {
-                LogEntry::AssistantItem { item, .. } => Some(item.clone()),
                 LogEntry::AnnotatedAssistantItem { entry, .. } => Some(entry.item.clone()),
                 _ => None,
             };
@@ -1207,11 +1206,11 @@ pub struct Worker<C: LlmClient, St: Store> {
     memory_task: Option<JoinHandle<()>>,
     /// Typed user submissions in submit order. K-th entry corresponds to
     /// the K-th `Item::user_message` in `worker.history()` (modulo seed
-    /// history loaded via `SegmentStart.history`, whose original segments
+    /// history loaded via `AnnotatedSegmentStart.history`, whose original segments
     /// are not preserved). Populated from log on `restore_from_manifest`,
     /// appended after `save_user_input` on each `run`. Pre-`Event::Snapshot`
     /// this fed `WorkerSharedState.user_segments`; the new wire format
-    /// carries typed atoms via `LogEntry::UserInput { segments }` so
+    /// carries typed atoms via `LogEntry::AnnotatedUserInput { segments }` so
     /// this remains purely an in-memory tracker for compact alignment.
     user_segments: Vec<Vec<Segment>>,
     /// Worker-side session-log mirror + broadcast sink. Populated alongside
@@ -1221,7 +1220,8 @@ pub struct Worker<C: LlmClient, St: Store> {
     sink: SegmentLogSink,
     /// `true` once `wire_history_persistence` has installed the
     /// `Engine::on_history_append` callback that commits each appended
-    /// item as a singular `LogEntry::AssistantItem` / `ToolResult`
+    /// item as a singular `LogEntry::AnnotatedAssistantItem` /
+    /// `AnnotatedToolResult`
     /// directly through the writer. Tests that drive `Worker::new` without
     /// going through the controller leave this `false`; `persist_turn`
     /// then walks the post-`history_before` slice inline so entries
@@ -1345,15 +1345,16 @@ impl<C: LlmClient + 'static, St: Store + Clone + 'static> Worker<C, St> {
     }
 
     /// Wire `Engine::on_history_append` to commit each appended item
-    /// directly as a singular `LogEntry::AssistantItem` / `ToolResult`
+    /// directly as a singular `LogEntry::AnnotatedAssistantItem` /
+    /// `AnnotatedToolResult`
     /// through the writer. The controller calls this once per spawned
     /// Worker after the worker is built; tests that drive `Worker::new` may
     /// opt in to the same wiring or leave it off (in which case
     /// `persist_turn`'s inline fallback writes entries at turn end).
     ///
     /// `user_message` items are skipped because they are committed
-    /// up-front via `commit_entry(LogEntry::UserInput { segments })`.
-    /// `role:system` items are committed as typed `LogEntry::SystemItem`
+    /// up-front via `commit_entry(LogEntry::AnnotatedUserInput { segments })`.
+    /// `role:system` items are committed as typed `LogEntry::AnnotatedSystemItem`
     /// entries by their producers (for example `WorkerInterceptor` and
     /// interrupted-turn prep) before they reach the worker's history, so this
     /// callback would otherwise double-write them.
@@ -1941,8 +1942,7 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
         }
 
         let input = match entries.get(target.user_input_entry_index) {
-            Some(LogEntry::UserInput { segments, .. })
-            | Some(LogEntry::AnnotatedUserInput { segments, .. }) => segments.clone(),
+            Some(LogEntry::AnnotatedUserInput { segments, .. }) => segments.clone(),
             _ => {
                 return Err(RewindError::Invalid(
                     "rewind target is no longer a user message".into(),
@@ -2081,8 +2081,8 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
     /// Cheap clone via `Option<Clone>`.
     /// Snapshot of the typed user segments tracked alongside worker
     /// history. The K-th entry corresponds to the K-th `Item::user_message`
-    /// derived from `LogEntry::UserInput` entries (post-compaction); seed
-    /// history loaded via `SegmentStart.history` does not contribute,
+    /// derived from `LogEntry::AnnotatedUserInput` entries (post-compaction); seed
+    /// history loaded via `AnnotatedSegmentStart.history` does not contribute,
     /// which is acceptable because the original segments are unrecoverable.
     pub fn user_segments(&self) -> &[Vec<Segment>] {
         &self.user_segments
@@ -3533,12 +3533,13 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
         // slice from `history_before` inline so the test's
         // `restore`-style assertions still see entries on disk.
         if !self.history_persistence_wired {
-            let new_items: Vec<Item> = self.session.history().entries()[history_before..]
+            let new_entries: Vec<_> = self.session.history().entries()[history_before..]
                 .iter()
-                .map(|entry| entry.item.clone())
+                .map(to_logged_history_entry)
                 .collect();
             let ts = segment_log::now_millis();
-            for item in &new_items {
+            for history_entry in new_entries {
+                let item = Item::from(history_entry.item.clone());
                 if item.is_user_message() {
                     continue;
                 }
@@ -3551,7 +3552,7 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
                 ) {
                     continue;
                 }
-                let entry = session_store::classify_history_item(item, ts);
+                let entry = session_store::classify_logged_history_entry(history_entry, ts);
                 self.commit_entry(entry)?;
             }
         }
@@ -6257,8 +6258,7 @@ fn build_rewind_targets(segment_id: uuid::Uuid, entries: &[LogEntry]) -> Vec<Rew
     let mut targets = Vec::new();
     for (entry_index, entry) in entries.iter().enumerate() {
         let (segments, ts) = match entry {
-            LogEntry::UserInput { segments, ts, .. }
-            | LogEntry::AnnotatedUserInput { segments, ts, .. } => (segments, ts),
+            LogEntry::AnnotatedUserInput { segments, ts, .. } => (segments, ts),
             _ => continue,
         };
         turn_index += 1;
@@ -6300,8 +6300,7 @@ fn rewind_truncate_entries(entries: &[LogEntry], user_input_entry_index: usize)
 
 fn suffix_has_tool_side_effects(entries: &[LogEntry]) -> bool {
     entries.iter().any(|entry| match entry {
-        LogEntry::ToolResult { .. } | LogEntry::AnnotatedToolResult { .. } => true,
-        LogEntry::AssistantItem { item, .. } => logged_item_is_tool_call(item),
+        LogEntry::AnnotatedToolResult { .. } => true,
         LogEntry::AnnotatedAssistantItem { entry, .. } => logged_item_is_tool_call(&entry.item),
         _ => false,
     })
@@ -7636,7 +7635,7 @@ mod build_summary_prompt_tests {
         );
         assert!(checkpoint.is_none());
 
-        let mut replacement_entries = vec![LogEntry::SegmentStart {
+        let mut replacement_entries = vec![LogEntry::AnnotatedSegmentStart {
             ts: segment_log::now_millis(),
             session_id: uuid::Uuid::nil(),
             system_prompt: None,
@@ -7964,9 +7963,12 @@ mod build_summary_prompt_tests {
         );
         append_test_entry(
             worker,
-            LogEntry::UserInput {
+            LogEntry::AnnotatedUserInput {
                 ts: ts + 1,
                 extensions: vec![],
+                history: vec![crate::session_history::test_logged_history_entry(
+                    Item::user_message(text),
+                )],
                 segments: vec![text_segment(text)],
             },
         );
@@ -7986,16 +7988,18 @@ mod build_summary_prompt_tests {
         append_user_turn(&worker, 20, "second message");
         append_test_entry(
             &worker,
-            LogEntry::ToolResult {
+            LogEntry::AnnotatedToolResult {
                 ts: 30,
-                item: session_store::LoggedItem::ToolResult {
-                    call_id: "call-1".into(),
-                    summary: "wrote a file".into(),
-                    content: None,
-                    attachments: Vec::new(),
-                    disposition: Default::default(),
-                    is_error: false,
-                },
+                entry: crate::session_history::test_logged_history_entry(
+                    session_store::LoggedItem::ToolResult {
+                        call_id: "call-1".into(),
+                        summary: "wrote a file".into(),
+                        content: None,
+                        attachments: Vec::new(),
+                        disposition: Default::default(),
+                        is_error: false,
+                    },
+                ),
             },
         );
 
@@ -8029,16 +8033,18 @@ mod build_summary_prompt_tests {
         append_user_turn(&worker, 20, "second message");
         append_test_entry(
             &worker,
-            LogEntry::ToolResult {
+            LogEntry::AnnotatedToolResult {
                 ts: 30,
-                item: session_store::LoggedItem::ToolResult {
-                    call_id: "call-1".into(),
-                    summary: "wrote a file".into(),
-                    content: None,
-                    attachments: Vec::new(),
-                    disposition: Default::default(),
-                    is_error: false,
-                },
+                entry: crate::session_history::test_logged_history_entry(
+                    session_store::LoggedItem::ToolResult {
+                        call_id: "call-1".into(),
+                        summary: "wrote a file".into(),
+                        content: None,
+                        attachments: Vec::new(),
+                        disposition: Default::default(),
+                        is_error: false,
+                    },
+                ),
             },
         );
         let (head_entries, targets) = worker.list_rewind_targets().unwrap();
@@ -8456,9 +8462,9 @@ mod build_summary_prompt_tests {
         worker.wire_history_persistence();
         let dangling_call = Item::tool_call("call-1", "SideEffect", "{}");
         worker
-            .commit_entry(LogEntry::AssistantItem {
+            .commit_entry(LogEntry::AnnotatedAssistantItem {
                 ts: segment_log::now_millis(),
-                item: dangling_call.clone().into(),
+                entry: crate::session_history::test_logged_history_entry(dangling_call.clone()),
             })
             .unwrap();
         worker.set_history_for_test(vec![dangling_call]);
@@ -8863,9 +8869,12 @@ mod build_summary_prompt_tests {
         );
         worker.set_history_for_test(vec![evidence.clone()]);
         worker
-            .commit_entry(LogEntry::UserInput {
+            .commit_entry(LogEntry::AnnotatedUserInput {
                 ts: segment_log::now_millis(),
                 extensions: vec![],
+                history: vec![crate::session_history::test_logged_history_entry(
+                    evidence.clone(),
+                )],
                 segments: vec![text_segment(
                     "The cancellation regression must leave this evidence available for retry.",
                 )],

crates/worker/tests/compact_events_test.rs

@@ -25,6 +25,17 @@ use worker::{Worker, WorkerController};
 
 type TestStore = CombinedStore<FsStore, FsWorkerStore>;
 
+fn annotated(item: Item) -> session_store::LoggedHistoryEntry {
+    session_store::LoggedHistoryEntry {
+        item: session_store::LoggedItem::from(item),
+        metadata: session_store::LoggedSessionHistoryMetadata {
+            entry_id: session_store::LoggedSessionHistoryEntryId::new(),
+            origin: session_store::LoggedSessionHistoryOrigin::LegacyUnknown,
+            derivation: None,
+        },
+    }
+}
+
 #[derive(Clone)]
 struct MockClient {
     responses: Arc<Vec<Vec<LlmEvent>>>,
@@ -210,7 +221,6 @@ fn system_texts_in_sink_session_start(
                 .into_iter()
                 .map(|entry| entry.item)
                 .collect::<Vec<_>>(),
-            session_store::LogEntry::SegmentStart { history, .. } => history,
             _ => continue,
         };
         return history
@@ -310,17 +320,14 @@ permission = "write"
     // Simulate a foreign writer appending to the same segment. This bumps
     // the on-disk entry count past the Worker's own append tally without
     // updating the Worker's `entries_written`.
-    store
-        .append(
-            session_id,
-            source_segment_id,
-            &LogEntry::UserInput {
-                ts: 9999,
-                segments: vec![protocol::Segment::text("interloper")],
-                extensions: vec![],
-            },
-        )
-        .unwrap();
+    session_store::save_user_input(
+        &store,
+        session_id,
+        source_segment_id,
+        vec![protocol::Segment::text("interloper")],
+        vec![annotated(Item::user_message("interloper"))],
+    )
+    .unwrap();
 
     // Next run triggers ensure_segment_head, which sees the drift.
     worker.run_text("second").await.unwrap();
@@ -348,11 +355,6 @@ permission = "write"
             session_id: seg_session,
             forked_from: Some(origin),
             ..
-        }
-        | LogEntry::SegmentStart {
-            session_id: seg_session,
-            forked_from: Some(origin),
-            ..
         } => {
             assert_eq!(*seg_session, session_id);
             assert_eq!(origin.segment_id, source_segment_id);
@@ -366,7 +368,7 @@ permission = "write"
     assert_eq!(source_after.len(), source_len_before + 1);
     assert!(matches!(
         source_after.last(),
-        Some(LogEntry::UserInput { .. })
+        Some(LogEntry::AnnotatedUserInput { .. })
     ));
 }
 

crates/worker/tests/controller_test.rs

@@ -35,29 +35,16 @@ fn history_from_sink(handle: &WorkerHandle) -> Vec<Item> {
             LogEntry::AnnotatedSegmentStart { history, .. } => {
                 items.extend(history.into_iter().map(|entry| Item::from(entry.item)));
             }
-            LogEntry::SegmentStart { history, .. } => {
-                items.extend(history.into_iter().map(Item::from));
-            }
             LogEntry::AnnotatedUserInput { history, .. } => {
                 items.extend(history.into_iter().map(|entry| Item::from(entry.item)));
             }
-            LogEntry::UserInput { segments, .. } => {
-                let text = protocol::Segment::flatten_to_text(&segments);
-                items.push(Item::user_message(text));
-            }
             LogEntry::AnnotatedAssistantItem { entry, .. }
             | LogEntry::AnnotatedToolResult { entry, .. } => {
                 items.push(Item::from(entry.item));
             }
-            LogEntry::AssistantItem { item, .. } | LogEntry::ToolResult { item, .. } => {
-                items.push(Item::from(item));
-            }
             LogEntry::AnnotatedSystemItem { entry, .. } => {
                 items.push(entry.item.to_history_item());
             }
-            LogEntry::SystemItem { item, .. } => {
-                items.push(item.to_history_item());
-            }
             _ => {}
         }
     }
@@ -67,7 +54,6 @@ fn history_from_sink(handle: &WorkerHandle) -> Vec<Item> {
 fn system_item(entry: &LogEntry) -> Option<&session_store::SystemItem> {
     match entry {
         LogEntry::AnnotatedSystemItem { entry, .. } => Some(&entry.item),
-        LogEntry::SystemItem { item, .. } => Some(item),
         _ => None,
     }
 }
@@ -839,26 +825,26 @@ async fn snapshot_includes_user_input_for_in_flight_turn() {
     loop {
         let event = reader.next::<Event>().await.unwrap().unwrap();
         match event {
-            Event::Snapshot { entries, .. } => {
-                // Walk the entries, find a `LogEntry::UserInput` and
-                // confirm its segments flatten to our submitted text.
-                let mut found = false;
-                for value in &entries {
-                    let entry: session_store::LogEntry =
-                        serde_json::from_value(value.clone()).expect("LogEntry deserialise");
-                    if let session_store::LogEntry::UserInput { segments, .. }
-                    | session_store::LogEntry::AnnotatedUserInput { segments, .. } = entry
-                    {
-                        let text = protocol::Segment::flatten_to_text(&segments);
-                        if text == "hello in-flight" {
-                            found = true;
-                            break;
-                        }
+            Event::Snapshot { session, .. } => {
+                let found = session.entries.iter().any(|entry| match &entry.data {
+                    protocol::SessionSnapshotEntryData::UserInput { segments } => {
+                        protocol::Segment::flatten_to_text(segments) == "hello in-flight"
                     }
-                }
+                    protocol::SessionSnapshotEntryData::Message {
+                        role: protocol::SessionMessageRole::User,
+                        content,
+                    } => content.iter().any(|part| {
+                        matches!(
+                            part,
+                            protocol::SessionContentPart::Text { text }
+                                if text == "hello in-flight"
+                        )
+                    }),
+                    _ => false,
+                });
                 assert!(
                     found,
-                    "snapshot must carry the in-flight UserInput entry: {entries:?}"
+                    "snapshot must carry the in-flight UserInput entry: {session:?}"
                 );
                 return;
             }
@@ -1095,7 +1081,7 @@ async fn run_with_paste_segment_inlines_content_and_emits_typed_user_message() {
     // Mixed input: plain text + a paste chip + trailing text. Worker must
     // flatten this into one user-message string (paste content inlined,
     // no `[Clipboard ...]` label leaking to the LLM); the committed
-    // `LogEntry::UserInput` must carry the typed segments unchanged so
+    // `LogEntry::AnnotatedUserInput` must carry the typed segments unchanged so
     // socket clients can derive `Event::UserMessage` and re-render the chip.
     let segments = vec![
         protocol::Segment::text("see "),
@@ -1130,7 +1116,7 @@ async fn run_with_paste_segment_inlines_content_and_emits_typed_user_message() {
                 _ => {}
             },
             entry = entry_rx.recv() => match entry {
-                Ok(session_store::LogEntry::UserInput { segments, .. } | session_store::LogEntry::AnnotatedUserInput { segments, .. }) => {
+                Ok(session_store::LogEntry::AnnotatedUserInput { segments, .. }) => {
                     user_input_segments = Some(segments);
                     if saw_turn_end {
                         break;
@@ -2410,17 +2396,12 @@ async fn snapshot_contains_user_input(handle: &WorkerHandle, needle: &str) -> bo
     loop {
         let event = reader.next::<Event>().await.unwrap().unwrap();
         match event {
-            Event::Snapshot { entries, .. } => {
-                return entries.into_iter().any(|value| {
-                    let entry: session_store::LogEntry =
-                        serde_json::from_value(value).expect("LogEntry deserialise");
-                    match entry {
-                        session_store::LogEntry::UserInput { segments, .. }
-                        | session_store::LogEntry::AnnotatedUserInput { segments, .. } => {
-                            protocol::Segment::flatten_to_text(&segments).contains(needle)
-                        }
-                        _ => false,
+            Event::Snapshot { session, .. } => {
+                return session.entries.into_iter().any(|entry| match entry.data {
+                    protocol::SessionSnapshotEntryData::UserInput { segments } => {
+                        protocol::Segment::flatten_to_text(&segments).contains(needle)
                     }
+                    _ => false,
                 });
             }
             Event::Alert(_) => continue,

crates/worker/tests/system_prompt_template_test.rs

@@ -203,12 +203,12 @@ async fn session_start_state_captures_rendered_prompt() {
         .unwrap();
     let first = entries.first().expect("at least one entry");
     match first {
-        LogEntry::SegmentStart { system_prompt, .. } => {
+        LogEntry::AnnotatedSegmentStart { system_prompt, .. } => {
             let sp = system_prompt.as_deref().expect("system prompt set");
             assert!(sp.starts_with("hello"));
             assert!(sp.contains(&pwd.display().to_string()));
         }
-        other => panic!("expected SegmentStart as first entry, got {other:?}"),
+        other => panic!("expected AnnotatedSegmentStart as first entry, got {other:?}"),
     }
 }
 

crates/workspace-server/src/server.rs

@@ -8557,7 +8557,7 @@ async fn scoped_capture_worker_observation_session(
                 message: "worker protocol closed before the session snapshot".to_string(),
             })
         })?;
-    let protocol::Event::Snapshot { entries, .. } = event else {
+    let protocol::Event::Snapshot { session, .. } = event else {
         return Err(ApiError::from(Error::RuntimeOperationFailed {
             runtime_id: target.runtime_id.clone(),
             code: "worker_observation_missing_snapshot".to_string(),
@@ -8566,7 +8566,7 @@ async fn scoped_capture_worker_observation_session(
     };
     Ok(Json(serde_json::json!({
         "segment_id": format!("runtime:{}:worker:{}", target.runtime_id, target.worker_id),
-        "entries": entries,
+        "session": session,
     })))
 }
 
@@ -16842,7 +16842,7 @@ mod tests {
         )
         .await
         .unwrap();
-        assert!(capture["entries"].is_array());
+        assert!(capture["session"]["entries"].is_array());
 
         let revoked = api
             .store