Keep archived workspaces recent in Done

packages/server/src/server/session.workspaces.test.ts

@@ -4356,6 +4356,62 @@ test("buildWorkspaceDescriptorMap computes statusEnteredAt from runtime agent fi
   }
 });
 
+test("buildWorkspaceDescriptorMap keeps a done workspace recent after its agents are archived", async () => {
+  const session = createSessionForWorkspaceTests();
+  const project = createPersistedProjectRecord({
+    projectId: "proj-archive-status-entered",
+    rootPath: REPO_CWD,
+    kind: "git",
+    displayName: "repo",
+    createdAt: "2026-03-01T12:00:00.000Z",
+    updatedAt: "2026-03-01T12:00:00.000Z",
+  });
+  const workspace = createPersistedWorkspaceRecord({
+    workspaceId: "ws-archive-status-entered",
+    projectId: project.projectId,
+    cwd: "/tmp/repo/archive-status-entered",
+    kind: "worktree",
+    displayName: "feature",
+    createdAt: "2026-03-01T12:00:00.000Z",
+    updatedAt: "2026-03-01T12:00:00.000Z",
+  });
+  const doneEnteredAt = "2026-05-12T09:30:00.000Z";
+  const archivedAt = "2026-05-12T09:45:00.000Z";
+
+  session.projectRegistry.list = async () => [project];
+  session.workspaceRegistry.list = async () => [workspace];
+  session.listAgentPayloads = async () => [
+    makeAgent({
+      id: "agent-done",
+      cwd: workspace.cwd,
+      status: "idle",
+      updatedAt: doneEnteredAt,
+    }),
+  ];
+
+  const first = await session.buildWorkspaceDescriptorMap({ includeGitData: false });
+  expect(first.get(workspace.workspaceId)?.status).toBe("done");
+  expect(first.get(workspace.workspaceId)?.statusEnteredAt).toBe(doneEnteredAt);
+
+  session.listAgentPayloads = async () => [
+    {
+      ...makeAgent({
+        id: "agent-done",
+        cwd: workspace.cwd,
+        status: "idle",
+        updatedAt: doneEnteredAt,
+      }),
+      archivedAt,
+    },
+  ];
+
+  const second = await session.buildWorkspaceDescriptorMap({ includeGitData: false });
+  expect(second.get(workspace.workspaceId)).toMatchObject({
+    status: "done",
+    statusEnteredAt: doneEnteredAt,
+  });
+});
+
 test("buildWorkspaceDescriptorMap stamps workspace archiving state", async () => {
   const session = createSessionForWorkspaceTests();
   const archivingAt = "2026-04-30T20:45:00.000Z";

packages/server/src/server/workspace-directory.ts

@@ -30,7 +30,7 @@ const FETCH_WORKSPACES_SORT_KEYS = [
  * mask to a lower-priority bucket, the new entry time is the unmask time
  * (i.e., the moment the higher-priority bucket cleared), not when the
  * underlying agent originally entered the lower-priority bucket. Cleared when
- * the workspace becomes `done` with no contributing agents.
+ * the workspace has never had contributing agents.
  */
 interface WorkspaceBucketHistoryEntry {
   bucket: WorkspaceStateBucket;
@@ -279,7 +279,10 @@ export class WorkspaceDirectory {
   //   - priority unmasking: when the winning bucket transitions (e.g. a
   //     higher-priority bucket cleared), the new entry time is "now";
   //   - same-bucket emits reuse the previous entered-at;
-  //   - empty workspaces (no contributing agents) get `statusEnteredAt: null`.
+  //   - empty workspaces that never had contributing agents get
+  //     `statusEnteredAt: null`.
+  //   - when archived agents leave a previously active workspace empty, keep
+  //     the previous done timestamp or stamp the transition to done now.
   private resolveStatusEnteredAt(params: {
     workspaceId: string;
     winningBucket: WorkspaceStateBucket;
@@ -294,16 +297,15 @@ export class WorkspaceDirectory {
     const { winningBucket, contributingAgents, previous, nowIso } = params;
 
     if (contributingAgents.length === 0) {
-      if (previous && previous.bucket !== "done") {
-        return { statusEnteredAt: null, recordDelete: true };
+      if (!previous) {
+        return { statusEnteredAt: null };
       }
-      if (previous) {
-        return {
-          statusEnteredAt: null,
-          recordUpdate: { bucket: "done", enteredAt: previous.enteredAt },
-        };
-      }
-      return { statusEnteredAt: null };
+
+      const enteredAt = previous.bucket === "done" ? previous.enteredAt : nowIso;
+      return {
+        statusEnteredAt: enteredAt,
+        recordUpdate: { bucket: "done", enteredAt },
+      };
     }
 
     if (!previous) {