fix(web): offer a just-authored preset on the new-session chip

Authoring writes a FILE, not a settings field, so nothing on the wire announces
it — `settings/changed` covers the default moving, never the directory. The
chip therefore kept the roster it read when it first mounted, and a preset
authored to be used was missing from the one screen that starts sessions.

The page that changes the directory now says so, and every surface reading the
same roster re-reads it. The chip subscribes rather than being reached from the
outer scope, because it is registered later, under `conversation`/`sessions`.

packages/client/ui-agent-preset/tests/apply.spec.ts

@@ -30,6 +30,21 @@ const ROSTER_ONE = {
   result: { ok: true as const, value: { presets: [{ id: 'standard', trust: 'system', isDefault: true }], authorable: true } },
 }
 
+/** The roster after this browser authored one preset of its own. */
+const ROSTER_AUTHORED = {
+  rpcId: 'r',
+  result: {
+    ok: true as const,
+    value: {
+      presets: [
+        { id: 'standard', trust: 'system', isDefault: true },
+        { id: 'mine', trust: 'user', isDefault: false },
+      ],
+      authorable: true,
+    },
+  },
+}
+
 /** The same roster with a second preset carrying the default. */
 const ROSTER_MOVED = {
   rpcId: 'r',
@@ -49,7 +64,7 @@ async function bench() {
   const ctx = new Context()
   // The host's answer, mutable so a spec can move the default the way the
   // settings surface does and watch who re-reads it.
-  let ROSTER: typeof ROSTER_ONE | typeof ROSTER_MOVED = ROSTER_ONE
+  let ROSTER: typeof ROSTER_ONE | typeof ROSTER_MOVED | typeof ROSTER_AUTHORED = ROSTER_ONE
   const moveDefault = (): void => { ROSTER = ROSTER_MOVED }
   await ctx.plugin(SlotsService).await()
   const locale = new LocaleService(ctx)
@@ -63,7 +78,13 @@ async function bench() {
           rpcId: 'r',
           result: { ok: true as const, value: { agentPreset: 'standard', trust: 'system', content: '', writable: false } },
         }),
-        write: () => Promise.resolve({ rpcId: 'r', result: { ok: true as const, value: { agentPreset: 'standard' } } }),
+        write: (payload: { agentPreset: string }) => {
+          calls.push(`write:${payload.agentPreset}`)
+          // The host's roster now contains it, which is the whole point of the
+          // write and what every surface must converge on.
+          ROSTER = ROSTER_AUTHORED
+          return Promise.resolve({ rpcId: 'r', result: { ok: true as const, value: { agentPreset: payload.agentPreset } } })
+        },
         remove: () => Promise.resolve({ rpcId: 'r', result: { ok: true as const, value: {} } }),
         select: (payload: { agentPreset: string }) => {
           calls.push(`select:${payload.agentPreset}`)
@@ -282,6 +303,35 @@ describe('ui-agent-preset apply', () => {
     conversation()
   })
 
+  it('offers a just-authored preset on the new-session chip', async () => {
+    const { ctx, slots } = await bench()
+    declareRoot(slots)
+    const conversation = declareConversation(slots)
+    ctx.provide('conversation', {} as never)
+    ctx.provide('sessions', sessionsDouble({ byId: {} }) as never)
+    await ctx.plugin({ inject: [...inject, 'conversation', 'sessions'], apply }).await()
+
+    const chip = slots.entries('conversation.hero.agentPreset')[0]!
+    const seat = (chip.inject as unknown as () => AgentPresetSeatInjected)()
+    await seat.load()
+    expect(seat.hooks.agentPresetSeat.getSnapshot().options.map(option => option.id)).toEqual(['standard'])
+
+    const section = (slots.entries('settings.section')[0]!.inject as unknown as () => AgentPresetSectionInjected)()
+    await section.load()
+    await section.createFrom()
+    section.setId('mine')
+    section.setName('我的模式')
+    await section.save()
+
+    // Authoring writes a file rather than a setting, so nothing on the wire
+    // announces it: a preset authored to be used must appear on the one screen
+    // that starts sessions, without a reload.
+    await vi.waitFor(() => {
+      expect(seat.hooks.agentPresetSeat.getSnapshot().options.map(option => option.id)).toEqual(['standard', 'mine'])
+    })
+    conversation()
+  })
+
   it('applies the staged choice to the blank session the flow lands on', async () => {
     const { ctx, slots, calls } = await bench()
     declareRoot(slots)