refactor(gui): slot system standard — single register, four props shares, framework store seat

The definitive slot model for the web client, replacing the first-generation
define/register two-step, ScopedSlots whitelist faces, and binding handles:

- 'root' is the only a-priori slot (SlotsService built-in); the shell renders
  exactly ctx.slots.renderSlot('root', {}).
- register is the single API: children = slot declaration + render
  authorization + runtime spec in one options object; misconfiguration fails
  loud at load (duplicate declaration, undeclared contribution, one store
  handle under two scopes).
- Component props arrive in four auto-derived shares: PropsRuntime<K>
  (owner params + session/global standard kits via declare-merge),
  PropsRenderSlots<S>, PropsStore<H>, and the inject business face.
  sessionId is framework-supplied; hooks are framework-made only.
- Framework store seat: defineStore factories declare schema/actions/persist;
  read = useStore, write = baked actions only; store scope derives from the
  mounting entry; per-session persist keys and clearPersisted lifecycle.
- inject factories read the apply closure's own ctx (binding handles retired;
  root-ctx back door closed); SessionProvider is self-wired render-prop.
- Rendering sits behind the SlotRenderer install seam; runtime stays
  React-free; ownership ledger keyed to the single entry axis closes the
  stale-authority window (StaleAuthorizationError probes).

Docs: the slot type-chain note is refreshed in place as the slot system
standard RFC (bilingual pair re-recorded); the web client architecture RFC
defers its slot sections there; packages/client/AGENTS.md gains the slot and
props discipline; gui-testing/web-styling notes drop missions/ references.

Tests: suites rewritten to the standard (props fed directly, real store
engines via createXXXStore().create(), no render machinery); load-time
negative samples for declaration/authorization/store conflicts; verified by
real-host playwright run (three columns, empty state, collapse, keyed session
remount, cross-slot selection sharing).

docs(ui-sidebar): point contract reference at the committed slot standard RFC

missions/ is workspace-local and never committed; the README must not cite it.

packages/client/ui-conversation/tests/chat-apply.spec.tsx

@@ -1,19 +1,18 @@
 // @vitest-environment jsdom
 // apply wiring: services provided, chat view + footer chrome registered, the
-// three slot registrations land against ui-layout-shaped specs, and the bash
-// samples resolve differentially (sub-session default scope). Full-chain
-// rendering belongs to the shell e2e; this spec stops at the assembly surface.
+// three slot registrations land against a root entry's children declarations
+// (the AppFrame role), the shared store handle rides both session slots, and
+// the bash samples resolve differentially (sub-session default scope).
+// Full-chain rendering belongs to the shell e2e; this spec stops at the
+// assembly surface.
 
 import { Context } from 'cordis'
 import { describe, expect, it, vi } from 'vitest'
-import { createSnapshotStore } from '@deepseek-ai/dsh-client-web-react'
+import { createSnapshotStore } from '@deepseek-ai/dsh-client-web-react/src/store/index.ts'
 import { SlotsService } from '@deepseek-ai/dsh-client-runtime/client'
 import type { SessionId, SessionListState } from '@deepseek-ai/dsh-client-runtime/client'
 import { apply, inject, ToolViewRegistry } from '@deepseek-ai/dsh-client-ui-conversation/client'
 import type { ConversationService } from '@deepseek-ai/dsh-client-ui-conversation/client'
-// Type-only: pulls ui-layout's SlotMap declaration merge into this spec's
-// program so the slot keys below typecheck in the client lane.
-import type {} from '@deepseek-ai/dsh-client-ui-layout/client'
 
 const ROOT = 'root-1' as SessionId
 const CHILD = 'child-1' as SessionId
@@ -29,31 +28,42 @@ async function bench() {
       [ROOT]: { id: ROOT, title: 'R', running: false, updatedAt: 1 },
       [CHILD]: { id: CHILD, title: 'C', parentId: ROOT, running: false, updatedAt: 2 },
     },
-  })
+    current: undefined,
+  } as SessionListState)
   const sessionsFake = {
     list: listStore,
     manager: { get: vi.fn() },
-    ancestry: () => [],
     scope: () => undefined,
+    cell: () => undefined,
     create: vi.fn(),
+    open: vi.fn(),
   }
   ctx.provide('sessions', sessionsFake)
-  ctx.provide('layout', {
-    current: createSnapshotStore<{ viewFor: Record<string, string> }>({ viewFor: {} }),
-    open: vi.fn(), openView: vi.fn(), openDetails: vi.fn(), closeDetails: vi.fn(),
-  })
+  ctx.provide('layout', { openDetails: vi.fn(), closeDetails: vi.fn() })
   ctx.provide('i18n', { bind: () => (key: string) => key })
 
-  // Specs owned by ui-layout in production; declared here so registrations land.
+  // Declared by ui-layout's root entry in production; a stand-in root
+  // occupant declares them here so the contributions land (it consumes
+  // renderSlot to satisfy the declare-means-render check).
   const slots = ctx.get('slots') as SlotsService
-  slots.define('conversation', { kind: 'single', scope: 'session' })
-  slots.define('details', { kind: 'single', scope: 'session' })
-  slots.define('conversation.empty', { kind: 'single', scope: 'root' })
+  slots.register({
+    name: 'root',
+    children: {
+      'conversation': { kind: 'single', scope: 'session' },
+      'details': { kind: 'single', scope: 'session' },
+      'conversation.empty': { kind: 'single', scope: 'root' },
+    },
+  }, (_p: { renderSlot?: unknown }) => null)
 
   const fiber = ctx.plugin({ inject: [...inject], apply })
   return { ctx, fiber, slots }
 }
 
+/** First stored entry for a key (inject/store live directly on StoredEntry). */
+function renderEntryOf(slots: SlotsService, key: 'conversation' | 'details' | 'conversation.empty') {
+  return slots.entries(key)[0] as undefined | { inject?: unknown; store?: unknown }
+}
+
 describe('apply wiring', () => {
   it('provides conversation and toolviews services', async () => {
     const b = await bench()
@@ -71,14 +81,20 @@ describe('apply wiring', () => {
     expect(views[0]?.chrome?.footer).toBeDefined()
   })
 
-  it('occupies conversation/details/conversation.empty with inject factories', async () => {
+  it('occupies the three slots; session pair shares one store handle, empty declares none', async () => {
     const b = await bench()
     await b.fiber.await()
-    for (const key of ['conversation', 'details', 'conversation.empty'] as const) {
-      const entries = b.slots.entries(key)
-      expect(entries, key).toHaveLength(1)
-      expect((entries[0]!.options as { inject?: unknown }).inject, key).toBeTypeOf('function')
-    }
+    const conversation = renderEntryOf(b.slots, 'conversation')
+    const details = renderEntryOf(b.slots, 'details')
+    const empty = renderEntryOf(b.slots, 'conversation.empty')
+    expect(conversation?.inject).toBeTypeOf('function')
+    expect(details?.inject).toBeTypeOf('function')
+    expect(empty?.inject).toBeTypeOf('function')
+    // The shared handle: one apply-built store value on BOTH session entries.
+    expect(conversation?.store).toBeDefined()
+    expect(details?.store).toBe(conversation?.store)
+    // The empty slot is storeless (local state + useSessions derivation).
+    expect(empty?.store).toBeUndefined()
   })
 
   it('bash samples resolve differentially: scoped row for sub-sessions, global for roots', async () => {