fix(desktop): make plugin SDK turn flags follow the focused chat

Follow-up to the salvaged #87558 commit: the PR's docs promised the flags
follow "the focused chat", but PRIMARY_SESSION_VIEW is the primary
workspace tab only — a focused session TILE would read the wrong chat.
Wire host.state.busy / host.state.awaitingResponse through the focused
slice ($focusedStoredSessionId / $focusedSessionState), same semantics
as the statusbar busy pulse, with the primary view (and its draft
fallback) while the workspace holds focus.

Adds a tile-focus vitest case and corrects the docs wording.

apps/desktop/src/sdk/index.test.ts

@@ -63,4 +63,51 @@ describe('host.state turn flags', () => {
     expect(host.state.busy.get()).toBe(false)
     expect(host.state.awaitingResponse.get()).toBe(false)
   })
+
+  it('follows a focused session tile, not the primary', async () => {
+    const tree = await import('@/components/pane-shell/tree/store')
+    const model = await import('@/components/pane-shell/tree/model')
+    const { registry } = await import('@/contrib/registry')
+    const { $sessionTiles } = await import('@/store/session-states')
+
+    // A second chat zone holding a session tile, next to the main workspace.
+    for (const id of ['workspace', 'session-tile:tile-a']) {
+      registry.register({
+        area: 'panes',
+        data: id === 'workspace' ? { placement: 'main', uncloseable: true } : { placement: 'main' },
+        id,
+        render: () => null,
+        title: id
+      })
+    }
+
+    tree.declareDefaultTree(
+      model.split('row', [
+        model.group(['workspace'], { active: 'workspace', id: 'grp-main' }),
+        model.group(['session-tile:tile-a'], { active: 'session-tile:tile-a', id: 'grp-side' })
+      ])
+    )
+
+    // Primary chat is idle; the tile's session is mid-turn.
+    setActiveSessionId('rt-primary')
+    publishSessionState('rt-primary', createClientSessionState('stored-primary'))
+    $sessionTiles.set([{ runtimeId: 'rt-tile-a', storedSessionId: 'tile-a' }])
+    publishSessionState('rt-tile-a', {
+      ...createClientSessionState('tile-a'),
+      awaitingResponse: true,
+      busy: true
+    })
+
+    // Focusing the tile zone moves the flags onto the tile's session…
+    tree.noteActiveTreeGroup('grp-side')
+    expect(host.state.busy.get()).toBe(true)
+    expect(host.state.awaitingResponse.get()).toBe(true)
+
+    // …and homing back to the workspace returns to the (idle) primary.
+    tree.noteActiveTreeGroup('grp-main')
+    expect(host.state.busy.get()).toBe(false)
+    expect(host.state.awaitingResponse.get()).toBe(false)
+
+    $sessionTiles.set([])
+  })
 })

apps/desktop/src/sdk/index.ts

@@ -18,10 +18,11 @@
  *  - `ui.*` — the design language, so plugin UI looks native by default.
  */
 
-import { atom, type ReadableAtom } from 'nanostores'
+import { atom, computed, type ReadableAtom } from 'nanostores'
 
 import { PRIMARY_SESSION_VIEW } from '@/app/chat/session-view'
 import { openSession, type OpenSessionIntent } from '@/app/open-session'
+import type { ClientSessionState } from '@/app/types'
 import { $narrowViewport } from '@/components/pane-shell/tree/store'
 import { onGatewayEvent } from '@/contrib/events'
 import { deleteProfile, getLogs, getStatus, type HermesGateway } from '@/hermes'
@@ -37,13 +38,44 @@ import {
   setActiveProfile,
   setShowAllProfiles
 } from '@/store/profile'
-import { $activeSessionId, $currentCwd, $currentModel, $gatewayState } from '@/store/session'
+import {
+  $activeSessionId,
+  $currentCwd,
+  $currentModel,
+  $gatewayState,
+  $selectedStoredSessionId
+} from '@/store/session'
+import { $focusedSessionState, $focusedStoredSessionId } from '@/store/session-states'
 import { runGatewayRestart } from '@/store/system-actions'
 
 // -- state: readonly views over the app's live atoms -------------------------
 
 const readonlyAtom = <T>(atomLike: ReadableAtom<T>): ReadableAtom<T> => atomLike
 
+/**
+ * Turn flag for the FOCUSED chat — same semantics as the statusbar's busy
+ * pulse. While the focused surface is the primary workspace (or a draft with
+ * no runtime slice yet) this reads the primary view, which itself falls back
+ * to the global draft atoms. Once a session TILE holds focus, the tile's own
+ * state slice is authoritative — a background session can never leak in.
+ */
+const focusedTurnFlag = (
+  select: (state: ClientSessionState) => boolean,
+  $primary: ReadableAtom<boolean>
+): ReadableAtom<boolean> =>
+  computed(
+    [$focusedStoredSessionId, $selectedStoredSessionId, $focusedSessionState, $primary],
+    (focused, selected, state, primary) =>
+      !focused || focused === selected ? primary : Boolean(state && select(state))
+  )
+
+const $focusedBusy = focusedTurnFlag(state => state.busy, PRIMARY_SESSION_VIEW.$busy)
+
+const $focusedAwaitingResponse = focusedTurnFlag(
+  state => state.awaitingResponse,
+  PRIMARY_SESSION_VIEW.$awaitingResponse
+)
+
 /** Window geometry + the app's responsive posture, one readonly rect. */
 export interface ViewportRect {
   width: number
@@ -71,13 +103,14 @@ export const host = {
     /** Runtime id of the active chat session (null on a fresh draft). */
     activeSessionId: readonlyAtom<null | string>($activeSessionId),
     /** True from send until the first assistant payload on the focused chat. */
-    awaitingResponse: readonlyAtom<boolean>(PRIMARY_SESSION_VIEW.$awaitingResponse),
+    awaitingResponse: readonlyAtom<boolean>($focusedAwaitingResponse),
     /**
      * True while the focused chat is working after a send. Covers the wait
-     * for the first token and the stream that follows. Same session as
-     * `activeSessionId`. A draft with no runtime id uses the global flag.
+     * for the first token and the stream that follows. Follows tile focus —
+     * same signal the statusbar's busy pulse reads. A draft with no runtime
+     * id uses the global flag.
      */
-    busy: readonlyAtom<boolean>(PRIMARY_SESSION_VIEW.$busy),
+    busy: readonlyAtom<boolean>($focusedBusy),
     /** Active workspace cwd ('' when detached). */
     cwd: readonlyAtom<string>($currentCwd),
     /** Gateway socket state: 'idle' | 'connecting' | 'open' | …. */

website/docs/developer-guide/desktop-plugin-sdk.md

@@ -409,7 +409,9 @@ probe) and `profiles.create` (`name`, `description`, `clone_from`,
 ws twins of the dashboard's `/api/profiles` REST routes.
 `host.state.busy` is the focused chat's live turn (thinking and streaming).
 `host.state.awaitingResponse` stays true from send until the first assistant
-payload. Both follow `activeSessionId`. Subscribe in a component:
+payload. Both follow the chat the user is actually looking at — the focused
+session tile when one holds focus, else the primary workspace chat (the same
+signal the statusbar's busy pulse reads). Subscribe in a component:
 
 ```javascript
 const busy = useValue(host.state.busy)