gui: fold Slack-origin sessions into Recent — drop the From Slack band

Mention-spawned sessions now list chronologically like any other session, in
both layouts; the row's origin icon (with the channel · workspace tooltip)
carries the provenance. The collapsed band hid fresh mentions below week-old
sessions. UX-DECISIONS §31 revised.

surfaces/gui/src/components/Sidebar.test.tsx

@@ -179,7 +179,7 @@ describe("From Slack group (§31)", () => {
     origin_label: "#general · T0AB",
   };
 
-  it("mention-spawned sessions collapse under From Slack with the platform icon, out of Recent", async () => {
+  it("mention-spawned sessions list chronologically in Recent with the platform icon (no band)", async () => {
     stubFetch([
       { match: "/v1/personas", method: "GET", json: PERSONAS },
       { match: "/v1/settings", method: "GET", json: { nav_layout: "flat" } },
@@ -187,20 +187,14 @@ describe("From Slack group (§31)", () => {
     render(<Sidebar {...baseProps} sessions={[...SESSIONS, SLACK_SESSION]} />);
     await screen.findByText("incident watch"); // flat Recent rendered
 
-    // Collapsed by default: the header shows a count, the row itself is hidden…
-    const toggle = screen.getByTestId("from-slack-toggle");
-    expect(toggle.textContent).toContain("From Slack (1)");
-    expect(screen.queryByText("#general — check the deploy?")).toBeNull();
-
-    // …and the session does NOT duplicate into the chronological Recent list.
-    fireEvent.click(toggle);
+    // No collapsed band — the session sits directly in the Recent list, exactly once…
+    expect(screen.queryByTestId("from-slack-toggle")).toBeNull();
     const row = await screen.findByText("#general — check the deploy?");
     expect(screen.getAllByText("#general — check the deploy?")).toHaveLength(1);
 
-    // The row wears the Slack logo, right-aligned in the indicator cluster.
-    const list = screen.getByTestId("from-slack-list");
-    expect(list.querySelector('[data-logo="slack"]')).toBeTruthy();
-    expect(row).toBeTruthy();
+    // …wearing the Slack logo in the row's indicator cluster.
+    const cluster = row.closest(".group");
+    expect(cluster?.querySelector('[data-logo="slack"]')).toBeTruthy();
   });
 });
 

surfaces/gui/src/components/Sidebar.tsx

@@ -339,15 +339,9 @@ export function Sidebar(props: Props) {
   const pinnedSessions = props.sessions.filter(
     (s) => s.pinned && !s.session_id.startsWith("__") && !s.archived,
   );
-  // §31: mention-spawned sessions gather in one cross-persona "From Slack" group, collapsed by
-  // default (owner call 2026-07-13; no auto-archive — a future global setting). Pinned wins.
-  const slackSessions = props.sessions
-    .filter(
-      (s) =>
-        s.origin === "slack" && !s.archived && !s.pinned && !s.session_id.startsWith("__"),
-    )
-    .sort((a, b) => (b.updated_at || "").localeCompare(a.updated_at || ""));
-  const [slackOpen, setSlackOpen] = useState(false);
+  // §31 (revised 2026-07-21): mention-spawned sessions list chronologically in Recent like any
+  // other session — the OriginIcon in the row's indicator cluster marks where they came from.
+  // The separate collapsed "From Slack" band hid fresh mentions below week-old sessions.
   // A row in the account menu (§26): closes the menu, then runs the destination.
   const appMenuItem = (
     icon: IconName,
@@ -411,9 +405,7 @@ export function Sidebar(props: Props) {
   // EXCLUDED here: they live in the cross-persona Pinned band only, so they don't repeat inside the
   // persona group / project list (matching the flat layout's Recent, which also drops pinned).
   const all = props.sessions.filter((s) => s.agent === browseKey && !s.session_id.startsWith("__"));
-  // Origin (mention-spawned) sessions live in the cross-persona "From Slack" band, not the
-  // persona lists — pinned still wins (Pinned band), and archived keeps the persona disclosure.
-  const mine = all.filter((s) => !s.archived && !s.pinned && !s.origin);
+  const mine = all.filter((s) => !s.archived && !s.pinned);
   const archived = all.filter((s) => s.archived);
   // Only PROJECT-SCOPED personas group sessions by project (git-bound Code, project-bound Ops).
   // Scratch/deliverable conversations are orphan (each has its own per-conversation scratch dir),
@@ -429,7 +421,7 @@ export function Sidebar(props: Props) {
   // Recent = every non-pinned, non-archived, real session across ALL personas, newest first
   // (by updated_at; missing timestamps keep store order), search-filtered. Drives the flat layout.
   const recentSessions = [...props.sessions]
-    .filter((s) => !s.archived && !s.session_id.startsWith("__") && !s.pinned && !s.origin)
+    .filter((s) => !s.archived && !s.session_id.startsWith("__") && !s.pinned)
     .filter((s) => personaVisible(s.agent))
     .filter(matches)
     .sort((a, b) => (b.updated_at || "").localeCompare(a.updated_at || ""));
@@ -705,27 +697,6 @@ export function Sidebar(props: Props) {
       </div>
     ) : null;
 
-  // §31: the collapsed cross-persona "From Slack" band — mention-spawned sessions, both layouts.
-  // Disclosure shape mirrors the persona body's Archived row.
-  const fromSlackBand = () =>
-    slackSessions.length > 0 ? (
-      <div>
-        <button
-          className="w-full flex items-center gap-1.5 px-1.5 py-1 rounded text-[10.5px] uppercase tracking-[0.07em] text-faint font-semibold hover:text-muted"
-          onClick={() => setSlackOpen((v) => !v)}
-          data-testid="from-slack-toggle"
-        >
-          <Icon name={slackOpen ? "chevronDown" : "chevronRight"} size={12} className="shrink-0" />
-          From Slack ({slackSessions.length})
-        </button>
-        {slackOpen && (
-          <div className="space-y-0.5 mt-0.5" data-testid="from-slack-list">
-            {slackSessions.map((s) => cardRow(s))}
-          </div>
-        )}
-      </div>
-    ) : null;
-
   // RECENT header with the group/filter control (§20) — the group toggle moved off the brand bar.
   // "Group by" flips the persona accordion ↔ chronological list; "Filter by coworker" narrows to
   // the checked personas (none checked = all shown).
@@ -1075,7 +1046,6 @@ export function Sidebar(props: Props) {
         <div className="space-y-4">
           {pinnedBand()}
           {scheduledBand()}
-          {fromSlackBand()}
           <div>
             {recentHeader()}
             {layout === "grouped" ? (