[AlemTuzlak]

What changed

TanStack AI 1.0

• All @tanstack/ai* packages bumped to 1.0.0; the 20 tracked exercise lockfiles regenerated (each passes npm ci --dry-run).
• 1.0 requires a threadId on useChat and chat(). Every chat panel keeps one stable id per mount with useState(() => crypto.randomUUID()); every route passes threadId through. Docs and instructor notes updated.

Typed tool parts (02.tools and 03.structured-replies)

• Tool definitions are split from server code: app/tools/products.ts + products.server.ts, variations.ts + variations.server.ts. The browser imports definitions only.
• product-chat.tsx passes the server tools' definitions plus the .client() tools to useChat({ tools }). Each tool-call part is now a union on part.name with a typed output, rendered with a switch and the components in the new app/components/tool-parts.tsx. The part.output as {...} and ProductCard casts are gone.
• Attendees write the switch starting in 02.01 and add one case per step. The components are imported and the line to uncomment is in each 🐨 comment.

Server merges client tools (02.02 onward)

• chat({ tools: mergeAgentTools([...serverTools], clientTools) }), with tools: clientTools from chatParamsFromRequest. Taught in 02.02, including why a plain [...server, ...client] spread is wrong: the browser sends parameters but chat() reads inputSchema, and it would duplicate the server tools.
• The shared definitions stay listed on the server. The browser only sends a name, description and input schema, so needsApproval, lazy and the output schema come from the server's copy. Checked with a mock adapter: if the server only has the browser's copy of addToCart, the browser runs it without asking for approval (only a console warning shows).

Problem apps no longer 500

• The 02.02 and 02.03 problem apps returned HTTP 500 on every page before the attendee had written anything: the browser imported navigateToDef / addToCartDef before they existed. The 🐨 comments now say to add that import after building the definition.

Review guide

1. exercises/02.tools/04.solution.make-tools-lazy: the finished pattern.
2. 02.01 problem vs solution: what attendees write first.
3. exercises/02.tools/02.problem.taking-the-user-around: where the merge is taught.
4. exercises/03.structured-replies/* copies the 02.04 solution's chat, tool-parts and tool files unchanged.

Verification

• typecheck in all 20 apps: solutions are clean except the existing app/epicshop.tsx error. Problem apps show only the intended "not built yet" errors.
• node ./epicshop/test.ts ..s: all 10 solution apps pass.
• Client build checked for server code leaks; the problem apps load and the chat opens with no console errors.
• Mock-adapter run of the merge: approve runs the tool and continues; deny skips it and sets approval.approved === false.
• Not tested against a real model: the local OpenRouter key is revoked.

Not in this PR

• The app/epicshop.tsx type error (from @epic-web/workshop-utils).
• npm run build failing on the top-level await prisma.$connect().
• The chat panel shows nothing when a run errors.

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