CL-6459: Keep every deliberately created agent workbench in the sidebar

apps/web/src/shell/sidebar-rows.test.ts

@@ -95,6 +95,64 @@ describe("buildSidebarRows", () => {
     expect(rows).toEqual([{ kind: "workbench", workbench: freshDm }]);
   });
 
+  test("every workbench deliberately created against the same agent definition keeps its own row (CL-6459)", () => {
+    const created = ["ch_new_1", "ch_new_2", "ch_new_3"].map((id, index) =>
+      workbench({
+        id,
+        kind: "chat",
+        title: "New Workbench",
+        definitionId: "wfd_myra",
+        participants: [{ address: "myra@acme.localhost", handle: "myra" }],
+        lastActivityAt: `2026-01-0${index + 1}T00:00:00.000Z`,
+      }),
+    );
+
+    const rows = buildSidebarRows([], created);
+
+    expect(rows.map((row) => row.workbench.id)).toEqual([
+      "ch_new_3",
+      "ch_new_2",
+      "ch_new_1",
+    ]);
+  });
+
+  test("a stale cross-tenant sibling drops without taking the live definition's deliberate workbenches with it", () => {
+    const staleAncestorDm = workbench({
+      id: "ch_myra_ancestor",
+      kind: "chat",
+      title: "Myra",
+      definitionId: "wfd_myra_ancestor",
+      participants: [{ address: "myra@acme.localhost", handle: "myra" }],
+      lastActivityAt: "2026-01-01T00:00:00.000Z",
+    });
+    const homeDm = workbench({
+      id: "ch_myra_home",
+      kind: "chat",
+      title: "Myra",
+      definitionId: "wfd_myra_leaf",
+      participants: [{ address: "myra@acme.localhost", handle: "myra" }],
+      lastActivityAt: "2026-01-04T00:00:00.000Z",
+    });
+    const createdWorkbench = workbench({
+      id: "ch_myra_new",
+      kind: "chat",
+      title: "New Workbench",
+      definitionId: "wfd_myra_leaf",
+      participants: [{ address: "myra@acme.localhost", handle: "myra" }],
+      lastActivityAt: "2026-01-05T00:00:00.000Z",
+    });
+
+    const rows = buildSidebarRows(
+      [],
+      [staleAncestorDm, homeDm, createdWorkbench],
+    );
+
+    expect(rows.map((row) => row.workbench.id)).toEqual([
+      "ch_myra_new",
+      "ch_myra_home",
+    ]);
+  });
+
   test("two distinct agents whose slugs humanize to the same title never collapse into one row (CL-6413)", () => {
     const researchAnalystHyphen = workbench({
       id: "ch_research_analyst_hyphen",

apps/web/src/shell/sidebar-rows.ts

@@ -31,49 +31,63 @@ function agentIdentityKey(chat: Workbench): string {
   return agentParticipant?.handle ?? chat.title;
 }
 
+type AgentChat = Workbench & { readonly definitionId: string };
+
+/** A group workbench never carries a `definitionId`; every agent DM does. */
+function isAgentChat(chat: Workbench): chat is AgentChat {
+  return chat.definitionId !== null && chat.definitionId !== undefined;
+}
+
+function activityOf(chat: Workbench): number {
+  return chat.lastActivityAt ? Date.parse(chat.lastActivityAt) : 0;
+}
+
 /**
- * Collapse agent-DM chats down to one row per agent identity (CL-6271).
+ * Drop agent-DM chats minted against a superseded sibling definition of
+ * the same agent (CL-6271), keeping every chat that belongs to the
+ * live one (CL-6459).
+ *
  * Shadowing already picks a single nearest definition per name in
  * `listVisibleAgentDefinitions`, but a DM chat is minted against a
  * specific definition id, so a caller who has separately DM'd the same
  * named agent (e.g. "Myra") launched from more than one ancestor tenant
  * ends up with one durable `Workbench` row per instance — the dedupe
- * there never runs again once a chat exists. Group every agent-DM chat
- * (identified by `definitionId` being set — a group workbench never
- * carries one) by `agentIdentityKey` and keep only the most recently
- * active row per group; the rest are stale siblings of an identity the
- * caller only ever needs to see once.
+ * there never runs again once a chat exists.
+ *
+ * `definitionId` is the discriminator that separates those stale
+ * cross-tenant siblings from workbenches a person deliberately created:
+ * "+ New Workbench" always mints against the bench's own currently
+ * resolved definition (`instant-agent-create.ts`), so N deliberate
+ * creations share one definition id and each keeps its row, while an
+ * ancestor tenant's leftover DM carries a different one. Per agent
+ * identity, the most recently active chat names the live definition;
+ * chats under any other definition are the stale siblings.
  */
-function dedupeAgentChatsByTitle(chats: readonly Workbench[]): Workbench[] {
-  const groupChats = chats.filter(
-    (chat) => chat.definitionId === null || chat.definitionId === undefined,
-  );
-  const agentChats = chats.filter(
-    (chat) => chat.definitionId !== null && chat.definitionId !== undefined,
-  );
+function dropSupersededAgentChats(chats: readonly Workbench[]): Workbench[] {
+  const groupChats = chats.filter((chat) => !isAgentChat(chat));
+  const agentChats = chats.filter(isAgentChat);
 
-  const newestByIdentity = new Map<string, Workbench>();
+  const liveDefinitionByIdentity = new Map<string, AgentChat>();
   for (const chat of agentChats) {
     const key = agentIdentityKey(chat);
-    const current = newestByIdentity.get(key);
-    const chatActivity = chat.lastActivityAt
-      ? Date.parse(chat.lastActivityAt)
-      : 0;
-    const currentActivity = current?.lastActivityAt
-      ? Date.parse(current.lastActivityAt)
-      : 0;
-    if (current === undefined || chatActivity > currentActivity) {
-      newestByIdentity.set(key, chat);
+    const current = liveDefinitionByIdentity.get(key);
+    if (current === undefined || activityOf(chat) > activityOf(current)) {
+      liveDefinitionByIdentity.set(key, chat);
     }
   }
 
-  return [...groupChats, ...newestByIdentity.values()];
+  return [
+    ...groupChats,
+    ...agentChats.filter(
+      (chat) =>
+        chat.definitionId ===
+        liveDefinitionByIdentity.get(agentIdentityKey(chat))?.definitionId,
+    ),
+  ];
 }
 
 function recencyOf(row: SidebarRow): number {
-  return row.workbench.lastActivityAt
-    ? Date.parse(row.workbench.lastActivityAt)
-    : 0;
+  return activityOf(row.workbench);
 }
 
 function isPinned(row: SidebarRow): boolean {
@@ -90,7 +104,7 @@ export function buildSidebarRows(
   workbenches: readonly Workbench[],
   chats: readonly Workbench[],
 ): readonly SidebarRow[] {
-  const dedupedChats = dedupeAgentChatsByTitle(chats);
+  const dedupedChats = dropSupersededAgentChats(chats);
   const rows: SidebarRow[] = [
     ...workbenches.map(
       (workbench) => ({ kind: "workbench", workbench }) as const,