diff --git a/crates/manifest/src/paths.rs b/crates/manifest/src/paths.rs
index d227ff4c..a8b0cf0b 100644
--- a/crates/manifest/src/paths.rs
+++ b/crates/manifest/src/paths.rs
@@ -5,6 +5,9 @@
 //! - **`config_dir`** — 人が手で書く / 編集する設定。`profiles.toml`,
 //!   `providers.toml`, `models.toml`, `prompts/`, `prompts.toml` 等
 //! - **`data_dir`** — プログラムが書く永続データ。`sessions/` 等
+//! - **`secret_data_dir`** — local secret store の読み書き base。既存
+//!   secret store は path-derived key を使うため、通常 data とは別に
+//!   legacy `$HOME/.yoi` を既定にする
 //! - **`runtime_dir`** — 再起動で消えてよいランタイム状態。socket,
 //!   `workers.json`, `pid` ファイル等
 //!
@@ -14,6 +17,7 @@
 //! |---|---|---|---|---|
 //! | config  | `YOI_CONFIG_DIR`  | `$YOI_HOME/config` | `$XDG_CONFIG_HOME/yoi` | `$HOME/.config/yoi` |
 //! | data    | `YOI_DATA_DIR`    | `$YOI_HOME`        | `$XDG_DATA_HOME/yoi`   | `$HOME/.local/share/yoi` |
+//! | secrets | `YOI_DATA_DIR`    | `$YOI_HOME`        | —                      | `$HOME/.yoi` |
 //! | runtime | `YOI_RUNTIME_DIR` | `$YOI_HOME/run`    | `$XDG_RUNTIME_DIR/yoi` | `$HOME/.yoi/run` |
 //!
 //! `YOI_HOME=$X` のとき config は `$X/config`、data は `$X` 直下、
@@ -47,6 +51,19 @@ pub fn data_dir() -> Option<PathBuf> {
     )
 }
 
+/// Secret store 用の data directory。
+///
+/// SecretStore は base path から復号 key を導出するため、通常 data dir の
+/// XDG fallback には追従させず、明示 override が無い場合は legacy
+/// `$HOME/.yoi` を読み書きする。
+pub fn secret_data_dir() -> Option<PathBuf> {
+    resolve_secret_data_dir_from_parts(
+        env_path("YOI_DATA_DIR"),
+        env_path("YOI_HOME"),
+        env_path("HOME"),
+    )
+}
+
 /// ランタイムディレクトリ。socket, `workers.json`, Worker ごとの `pid` /
 /// `status.json` 等が置かれる。再起動で消えて構わない。
 pub fn runtime_dir() -> Option<PathBuf> {
@@ -147,6 +164,20 @@ fn resolve_data_dir_from_parts(
     Some(home?.join(".local").join("share").join("yoi"))
 }
 
+fn resolve_secret_data_dir_from_parts(
+    yoi_data_dir: Option<PathBuf>,
+    yoi_home: Option<PathBuf>,
+    home: Option<PathBuf>,
+) -> Option<PathBuf> {
+    if let Some(p) = yoi_data_dir {
+        return Some(p);
+    }
+    if let Some(p) = yoi_home {
+        return Some(p);
+    }
+    Some(home?.join(".yoi"))
+}
+
 fn resolve_runtime_dir_from_parts(
     yoi_runtime_dir: Option<PathBuf>,
     yoi_home: Option<PathBuf>,
@@ -322,6 +353,40 @@ mod tests {
         );
     }
 
+    #[test]
+    fn secret_data_dir_falls_back_to_home_dot_yoi() {
+        assert_eq!(
+            resolve_secret_data_dir_from_parts(None, None, Some(PathBuf::from("/h"))).unwrap(),
+            PathBuf::from("/h/.yoi")
+        );
+    }
+
+    #[test]
+    fn secret_data_dir_yoi_home_wins() {
+        assert_eq!(
+            resolve_secret_data_dir_from_parts(
+                None,
+                Some(PathBuf::from("/sand")),
+                Some(PathBuf::from("/h"))
+            )
+            .unwrap(),
+            PathBuf::from("/sand")
+        );
+    }
+
+    #[test]
+    fn secret_data_dir_explicit_wins_over_yoi_home() {
+        assert_eq!(
+            resolve_secret_data_dir_from_parts(
+                Some(PathBuf::from("/explicit-data")),
+                Some(PathBuf::from("/sand")),
+                Some(PathBuf::from("/h")),
+            )
+            .unwrap(),
+            PathBuf::from("/explicit-data")
+        );
+    }
+
     #[test]
     fn runtime_dir_prefers_xdg_runtime_dir() {
         assert_eq!(
diff --git a/crates/tools/src/web.rs b/crates/tools/src/web.rs
index 3634db26..b9c829e8 100644
--- a/crates/tools/src/web.rs
+++ b/crates/tools/src/web.rs
@@ -47,7 +47,7 @@ impl WebTools {
             .user_agent("yoi-web-tools/0.1")
             .build()
             .expect("static reqwest client configuration is valid");
-        let secret_store = manifest::paths::data_dir().map(SecretStore::new);
+        let secret_store = manifest::paths::secret_data_dir().map(SecretStore::new);
         Self {
             config,
             client,
diff --git a/crates/tui/src/keys.rs b/crates/tui/src/keys.rs
index 277865ef..0b2c69f7 100644
--- a/crates/tui/src/keys.rs
+++ b/crates/tui/src/keys.rs
@@ -218,10 +218,10 @@ impl std::fmt::Debug for Action {
 }
 
 pub async fn launch() -> ExitCode {
-    let data_dir = match manifest::paths::data_dir() {
+    let data_dir = match manifest::paths::secret_data_dir() {
         Some(path) => path,
         None => {
-            eprintln!("yoi keys: could not determine yoi data directory");
+            eprintln!("yoi keys: could not determine yoi secret data directory");
             return ExitCode::FAILURE;
         }
     };
diff --git a/crates/worker/src/model_client.rs b/crates/worker/src/model_client.rs
index 6574ec1a..80dffebb 100644
--- a/crates/worker/src/model_client.rs
+++ b/crates/worker/src/model_client.rs
@@ -70,11 +70,11 @@ struct DefaultSecretResolver;
 
 impl SecretResolver for DefaultSecretResolver {
     fn get_secret(&self, id: &str) -> Result<SecretValue, secrets::Error> {
-        let data_dir = manifest::paths::data_dir().ok_or_else(|| secrets::Error::Read {
-            path: std::path::PathBuf::from("<data_dir>"),
+        let data_dir = manifest::paths::secret_data_dir().ok_or_else(|| secrets::Error::Read {
+            path: std::path::PathBuf::from("<secret_data_dir>"),
             source: std::io::Error::new(
                 std::io::ErrorKind::NotFound,
-                "could not determine yoi data directory",
+                "could not determine yoi secret data directory",
             ),
         })?;
         SecretStore::new(data_dir).get(id)