fix(handoff): scope the recent-files list to the latest session

packages/cli/src/commands/handoff.test.ts

@@ -196,15 +196,21 @@ describe("basou handoff generate", () => {
     expect(joinCalls(out)).toContain("sessions: 1");
   });
 
-  it("case 3: aggregates multiple sessions and unions related_files", async () => {
+  it("case 3: 直近の変更ファイル shows only the most recent session's related_files", async () => {
     const repo = await setupInitedRepo();
+    // Older session — its files must NOT appear once a newer session supersedes it.
     await placeSession(repo, { id: SES("X02"), relatedFiles: ["src/a.ts"] });
-    await placeSession(repo, { id: SES("X03"), relatedFiles: ["src/b.ts"] });
+    // More recent session (later started_at) — this one wins.
+    await placeSession(repo, {
+      id: SES("X03"),
+      relatedFiles: ["src/b.ts"],
+      startedAt: "2026-05-08T12:00:00+09:00",
+    });
     const out = captureStdout();
     await doRunHandoffGenerate({}, { cwd: repo, nowProvider: () => FIXED_DATE });
     expect(joinCalls(out)).toContain("sessions: 2");
     const body = await readFile(basouPaths(repo).files.handoff, "utf8");
-    expect(body).toContain("- src/a.ts");
+    expect(body).not.toContain("- src/a.ts");
     expect(body).toContain("- src/b.ts");
   });
 

packages/core/src/handoff/handoff-renderer.test.ts

@@ -250,28 +250,29 @@ describe("handoff-renderer", () => {
     expect(result.body).toContain(`from ${SHORT(id)}..${SHORT(id)}`);
   });
 
-  it("case 3: aggregates related_files across sessions and dedups", async () => {
+  it("case 3: 直近の変更ファイル shows only the most recent session's related_files", async () => {
     const paths = await setupPaths();
+    // Older session — its unique files must NOT appear once a newer session
+    // supersedes it.
     await placeSession(paths, {
       id: SES("X02"),
       relatedFiles: ["src/a.ts", "src/b.ts"],
     });
+    // More recent session (later started_at) — this one wins.
     await placeSession(paths, {
       id: SES("X03"),
       relatedFiles: ["src/b.ts", "src/c.ts"],
       startedAt: "2026-05-08T12:00:00+09:00",
     });
     const result = await renderHandoff({ paths, nowIso: FIXED_NOW_ISO });
     expect(result.sessionCount).toBe(2);
-    // dedup + sort asc, scoped to the 直近の変更ファイル section. The next-to-
-    // read section deliberately reuses `displayedFiles.slice(0, 3)`, so a
-    // global count would over-report by design.
     const recentSection = sliceSection(result.body, "## 直近の変更ファイル", "##");
-    const idxA = recentSection.indexOf("- src/a.ts");
+    // src/a.ts is only in the older session, so it is excluded; the newer
+    // session's files appear, sorted asc.
+    expect(recentSection).not.toContain("- src/a.ts");
     const idxB = recentSection.indexOf("- src/b.ts");
     const idxC = recentSection.indexOf("- src/c.ts");
-    expect(idxA).toBeGreaterThanOrEqual(0);
-    expect(idxB).toBeGreaterThan(idxA);
+    expect(idxB).toBeGreaterThanOrEqual(0);
     expect(idxC).toBeGreaterThan(idxB);
     expect(recentSection.split("- src/b.ts\n").length - 1).toBe(1);
   });

packages/core/src/handoff/handoff-renderer.ts

@@ -75,7 +75,7 @@ type TaskStatusChangedRecord = {
  * the spec's `handoff.md` sections in order:
  *
  * 1. `現在の状態`: latest live session (status not archived, source not import).
- * 2. `直近の変更ファイル`: union of `related_files` across sessions, dedup +
+ * 2. `直近の変更ファイル`: the most recent session's `related_files`, dedup +
  *    sorted asc + truncated to `relatedFilesLimit` (default 20).
  * 3. `直近の判断`: latest `decision_recorded` event (chronological).
  * 4. `未決事項`: pending-approval count + suspect-session count.
@@ -202,16 +202,14 @@ export async function renderHandoff(input: HandoffRendererInput): Promise<Handof
     (a, b) => Date.parse(b.session.session.started_at) - Date.parse(a.session.session.started_at),
   )[0];
 
-  // 「直近の変更ファイル」 collects related_files from live sessions only.
-  // Imported sessions are historical / cross-workspace and would otherwise
-  // pollute the "what changed recently" view with paths that don't belong
-  // to the current workspace's live work.
-  const allFiles = new Set<string>();
-  for (const e of entries) {
-    if (e.session.session.source.kind === "import") continue;
-    for (const f of e.session.session.related_files) allFiles.add(f);
-  }
-  const sortedFiles = [...allFiles].sort();
+  // 「直近の変更ファイル」 shows the files touched by the single most recent
+  // session — the same session surfaced as 最終 session above — so the section
+  // reflects the latest activity rather than the whole history. Unioning every
+  // session's related_files turned this into a whole-history dump once
+  // transcript imports became the primary source, since each import carries a
+  // full day of file changes.
+  const latestFiles = latestSession?.session.session.related_files ?? [];
+  const sortedFiles = [...new Set(latestFiles)].sort();
   const displayedFiles = sortedFiles.slice(0, limit);
   const overflow = Math.max(0, sortedFiles.length - limit);