fix(client): publish current session provide bundle as one reactive projection

A provider roster change under a stable current id rematerialized every
scope's bundle but nothing notified React: SessionProvider resolved the
bundle from a current-id subscription only, so mounted entries kept the
obsolete hook/prop schema until an unrelated re-render. The sessions
service now owns an atomic currentProvide observable fed by both current
writes and roster changes; the renderer host exposes it as
sessions.provide, replacing the current/provideInfo/maybeProvideInfo
trio, and both providers subscribe to it.

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

@@ -87,12 +87,13 @@ async function bench() {
     }
   }
   const providers: TestProvider[] = []
+  const absentInfo = { sessionId: undefined, hooks: {}, props: {} }
   const sessionsFake = {
     list: listStore,
     binding: (id: SessionId) => ({ sessionId: id, session: sessionFake, ctx: mint(id) }),
     scope: (id: SessionId) => mint(id),
     provideInfo: () => undefined,
-    maybeProvideInfo: () => ({ hooks: {}, props: {} }),
+    currentProvide: { getSnapshot: () => absentInfo, subscribe: () => () => {} },
     provide: (descriptor: TestProvider) => { providers.push(descriptor); return () => {} },
     scopeOf,
     sessionOf: (actx: Context) => (scopeOf(actx) === undefined ? undefined : sessionFake),

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

@@ -32,12 +32,13 @@ async function bench() {
     current: undefined,
     phase: 'ready',
   })
+  const absentInfo = { sessionId: undefined, hooks: {}, props: {} }
   const sessionsFake = {
     list: listStore,
     binding: vi.fn(),
     scope: () => undefined,
     provideInfo: () => undefined,
-    maybeProvideInfo: () => ({ hooks: {}, props: {} }),
+    currentProvide: { getSnapshot: () => absentInfo, subscribe: () => () => {} },
     provide: vi.fn(() => () => {}),
     create: vi.fn(),
     open: vi.fn(),

packages/client/ui-conversation/tests/chat-code-subcalls.spec.tsx

@@ -87,6 +87,9 @@ async function bench(snapshot: ConversationSnapshot) {
   // Provide-channel contributions land in this bundle the way the runtime
   // materializes them; the renderer host serves it through provideInfo.
   const provided: { hooks: Record<string, unknown>; props: Record<string, unknown> } = { hooks: {}, props: {} }
+  // Identity-stable currentProvide snapshot (uSES getSnapshot contract),
+  // materialized on first render after the provide contributions landed.
+  let infoCell: { sessionId: SessionId; hooks: Record<string, unknown>; props: Record<string, unknown> } | undefined
   const sessionsFake = {
     list,
     binding: (id: SessionId) => (id === SID
@@ -103,9 +106,10 @@ async function bench(snapshot: ConversationSnapshot) {
     provideInfo: (id: string) => (id === SID
       ? { sessionId: SID, hooks: { session, ...provided.hooks }, props: provided.props }
       : undefined),
-    maybeProvideInfo: (id: string | undefined) => (id === SID
-      ? { sessionId: SID, hooks: { session, ...provided.hooks }, props: provided.props }
-      : { hooks: provided.hooks, props: provided.props }),
+    currentProvide: {
+      getSnapshot: () => infoCell ??= { sessionId: SID, hooks: { session, ...provided.hooks }, props: provided.props },
+      subscribe: () => () => {},
+    },
     create: vi.fn(),
     open: vi.fn(),
   }

packages/client/ui-conversation/tests/chat-toolview-slot.spec.tsx

@@ -24,6 +24,9 @@ import type { ToolRowProps } from '@deepseek-ai/dsh-client-ui-conversation/clien
 
 const SID = 's1' as SessionId
 
+/** Identity-stable no-session bundle (uSES getSnapshot contract). */
+const ABSENT_INFO = { sessionId: undefined, hooks: {}, props: {} }
+
 afterEach(cleanup)
 // The chat store persists under its declared key; clear between cases.
 beforeEach(() => {
@@ -89,30 +92,28 @@ async function bench(nodes: ToolResultNode[]) {
       subscribe: (fn: () => void) => session.subscribe(fn),
     },
   })
+  const provideInfo = (id: string) => {
+    if (id !== SID) return undefined
+    if (info === undefined) {
+      const hooks: Record<string, unknown> = { session }
+      const props: Record<string, unknown> = {}
+      for (const provider of providers) {
+        const c = provider(bindingOf(SID))
+        Object.assign(hooks, c.hooks ?? {})
+        Object.assign(props, c.props ?? {})
+      }
+      info = { sessionId: SID, hooks, props }
+    }
+    return info
+  }
   ctx.provide('sessions', {
     list,
     binding: bindingOf,
     scope: () => actxFake,
-    provideInfo: (id: string) => {
-      if (id !== SID) return undefined
-      if (info === undefined) {
-        const hooks: Record<string, unknown> = { session }
-        const props: Record<string, unknown> = {}
-        for (const provider of providers) {
-          const c = provider(bindingOf(SID))
-          Object.assign(hooks, c.hooks ?? {})
-          Object.assign(props, c.props ?? {})
-        }
-        info = { sessionId: SID, hooks, props }
-      }
-      return info
-    },
-    maybeProvideInfo(id: string | undefined) {
-      // `this` inside an object-literal method is any under strict lint; the
-      // fake resolves through its own provideInfo above.
-      /* eslint-disable-next-line @typescript-eslint/no-unsafe-return,
-         @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-member-access */
-      return (id === undefined ? undefined : this.provideInfo(id)) ?? { hooks: {}, props: {} }
+    provideInfo,
+    currentProvide: {
+      getSnapshot: () => provideInfo(SID),
+      subscribe: () => () => {},
     },
     provide: (d: { resolve: (typeof providers)[number] }) => { providers.push(d.resolve); return () => {} },
     scopeOf: () => SID,
@@ -254,7 +255,10 @@ describe('registrant load-order seam', () => {
       binding: () => undefined,
       scope: () => undefined,
       provideInfo: () => undefined,
-      maybeProvideInfo: () => ({ hooks: {}, props: {} }),
+      currentProvide: {
+        getSnapshot: () => ABSENT_INFO,
+        subscribe: () => () => {},
+      },
       provide: () => () => {},
       create: vi.fn(),
       open: vi.fn(),

packages/client/ui-conversation/tests/selection-survival.spec.ts

@@ -11,6 +11,9 @@ import { createChatStore } from '../src/client/stores.ts'
 
 const sid = (s: string): SessionId => s as SessionId
 
+/** Identity-stable no-session bundle (uSES getSnapshot contract). */
+const ABSENT_INFO = { sessionId: undefined, hooks: {}, props: {} }
+
 interface Bench {
   slots: SlotsService
   chat: ReturnType<typeof createChatStore>
@@ -23,7 +26,10 @@ function bench(): Bench {
       ids: [], byId: {}, current: undefined, phase: 'ready',
     }),
     provideInfo: () => undefined,
-    maybeProvideInfo: () => ({ hooks: {}, props: {} }),
+    currentProvide: {
+      getSnapshot: () => ABSENT_INFO,
+      subscribe: () => () => {},
+    },
     provide: () => () => {},
   })
   ctx.provide('workspaces', {