useChat external store on ChatClient (approach 3/3: @tanstack/store)

[tombeckenham]

Draft / experiment — approach 3 of 3. See #5 for the full writeup and motivation. Base is feat/chat-client-persistence so the diff is only the relevant change.

Back ChatClient's state with @tanstack/store

Same goal as approach 2 (#6) — one external-store primitive on ChatClient, shared across frameworks — but using @tanstack/store instead of a hand-rolled subscribe/getSnapshot.

ai-client

• Add @tanstack/store dependency.
• Export ChatClientSnapshot and add readonly store: Store<ChatClientSnapshot> to ChatClient, seeded in the constructor.
• Each setX mutator and the messages handler calls syncStore(), which projects current state into the Store. The onXChange callbacks stay intact for existing consumers — the Store is additive.

ai-react

• Add @tanstack/react-store dependency.
• The hook reads client.store via useStore:

const snapshot = useStore(client.store)
// or scope re-renders per field: useStore(client.store, s => s.messages)

Trade-off vs approach 2 (hand-rolled)

Pros: much less hand-written plumbing, and free selector support (useStore(store, selector)) to scope re-renders per field — useful for token-by-token streaming. It's also the "most TanStack" option.
Cons: two new dependencies (@tanstack/store in ai-client, @tanstack/react-store in ai-react).

Verification

tsc, ESLint (0 errors), all 376 ai-client + 128 ai-react tests pass. (Typecheck requires building ai-client first, since ai-react resolves it via dist types.)

🤖 Generated with Claude Code

[github-actions]

🚀 Changeset Version Preview

6 package(s) bumped directly, 5 bumped as dependents.

🟥 Major bumps

Package	Version	Reason
@tanstack/ai-elevenlabs	0.2.17 → 1.0.0	Dependent
@tanstack/ai-openai	0.12.0 → 1.0.0	Dependent
@tanstack/ai-react-ui	0.8.5 → 1.0.0	Dependent
@tanstack/ai-solid-ui	0.7.5 → 1.0.0	Dependent

🟨 Minor bumps

Package	Version	Reason
@tanstack/ai-client	0.15.2 → 0.16.0	Changeset
@tanstack/ai-preact	0.8.2 → 0.9.0	Changeset
@tanstack/ai-react	0.14.2 → 0.15.0	Changeset
@tanstack/ai-solid	0.12.2 → 0.13.0	Changeset
@tanstack/ai-svelte	0.12.2 → 0.13.0	Changeset
@tanstack/ai-vue	0.12.2 → 0.13.0	Changeset

🟩 Patch bumps

Package	Version	Reason
@tanstack/ai-vue-ui	0.2.11 → 0.2.12	Dependent