## Summary `useDefaultRenderTool`'s `render` was typed to return `React.ReactElement`. A caller who wants to render only *some* tool calls therefore could not return `null` to suppress the built-in default for the rest — the value flowed through correctly at runtime, but the type rejected it. This widens the public `render` return type, and the wrapper local that carries the user's value, to `React.ReactElement | null`. ```diff - render?: (props: DefaultRenderProps) => React.ReactElement; + render?: (props: DefaultRenderProps) => React.ReactElement | null; ``` The reference page hand-writes the same signature, so it is updated to match, with one behavior bullet describing what `null` does. ## Scope, and its relationship to #6533 #6533 already widens the same return type to `React.ReactElement | null` in `defineToolCallRenderer.ts` and `use-render-tool.tsx`. It does **not** touch `use-default-render-tool.tsx`, which is the remaining gap and the whole of this PR. There is **no file overlap**, so the two can land in either order. A structural sweep of `react-core/src/v2` for renders still typed `=> React.ReactElement` with no `| null` confirms this leaves nothing behind on this surface: ``` types/defineToolCallRenderer.ts:40,48,56 <- #6533 hooks/use-render-tool.tsx:41,72,109 <- #6533 hooks/use-default-render-tool.tsx:152 <- the deliberate bridge cast, below hooks/use-interrupt.tsx:89 <- different surface, out of scope components/chat/CopilotChatMessageView.tsx:418 <- different surface, out of scope ``` The `as unknown as` cast into `useRenderTool` is deliberately left in place: `useRenderTool` still requires a `ReactElement` return on `main` (verified again after the rebase — `use-render-tool.tsx:41`). Once #6533 lands, that cast can be tightened. The bridge comment is updated to say so. `DefaultToolCallRenderer`'s own return type stays `React.ReactElement` — the built-in default always renders an element. The Vue counterpart needs no equivalent change: its `render` already returns `VNodeChild`, which admits `null`, and `reference/vue/hooks/useDefaultRenderTool.mdx` already matches. ## Why the guard is a type test, not a runtime test TypeScript types are erased, so a `null`-returning render forwards identically before and after the widening. The runtime test passes against un-widened source, which makes it worthless as a guard for this change. So the real guard is `use-default-render-tool-types.test-d.ts`, using the `expectTypeOf` + `toEqualTypeOf` convention already documented in `v2/__tests__/headless-type-exports.test-d.ts`. `toEqualTypeOf` is required rather than assignability: a function returning `ReactElement` **is** assignable to one returning `ReactElement | null`, so an assignability check would pass against the un-widened type and assert nothing. The `.test-d.ts` basename is outside vitest's `include` globs, so nothing there executes; `tsc --noEmit` (`check-types`) is what reads it. Confirmed on this base: ``` $ vitest list --filesOnly | grep -c "test-d" 0 $ grep -n include -A4 packages/react-core/vitest.config.mjs include: [ "src/**/__tests__/**/*.{test,spec}.{ts,tsx}", "src/**/*.{test,spec}.{ts,tsx}", ], $ grep include packages/react-core/tsconfig.json "include": ["src/**/*"], ``` The runtime test is kept as well, since it still covers prop adaptation and forwarding. ## Testing All numbers below were re-measured after the rebase onto `main` (`42494df`). **Mutation check of the type guard** — revert the widening in the source, confirm the guard goes red: ``` ########## RUN A: rebased HEAD as-is ########## total errors: 63 --- errors in touched files --- none ########## RUN B: MUTATION - widening reverted in source ########## total errors: 65 --- guard file errors (expect FAIL) --- use-default-render-tool-types.test-d.ts(26,3): error TS2344: Type '((props: DefaultRenderProps) => ReactElement<...> | null) | undefined' does not satisfy the constraint '"Expected: undefined, Actual: never" | "Expected: function, Actual: never"'. use-default-render-tool.test.tsx(150,30): error TS2322: Type 'Mock<({ status }: DefaultRenderProps) => null>' is not assignable to type '(props: DefaultRenderProps) => ReactElement<...>'. Type 'null' is not assignable to type 'ReactElement<...>'. ``` The guard fails when the widening is reverted, and the two new errors are exactly the guard plus the runtime test's own use of it. Nothing else moves. **Typecheck** (`tsc -p packages/react-core --noEmit`) — error set byte-identical to pristine `origin/main` in the same worktree, none in the touched files: ``` ########## RUN C: pristine origin/main baseline ########## total errors on pristine main: 63 === diff: pristine-main errors vs HEAD errors === IDENTICAL -> the change introduces no new type errors ``` The 63 are pre-existing worktree noise: `react-core` resolves `@copilotkit/core` and `@copilotkit/shared` from a sibling checkout's `dist`, so unrelated exports read as missing. They are present on pristine `origin/main` in the same worktree, which is what the diff above shows. **Target test file:** ``` ✓ src/v2/hooks/__tests__/use-default-render-tool.test.tsx (13 tests) 38ms Test Files 1 passed (1) Tests 13 passed (13) ``` **Broader `src/v2/hooks` + `src/v2/types`** — failure counts identical to pristine `origin/main` in the same worktree, plus exactly the one new passing test: ``` === BASELINE (pristine origin/main in this worktree) === Test Files 22 failed | 17 passed (39) Tests 9 failed | 201 passed (210) === WITH my change === Test Files 22 failed | 17 passed (39) Tests 9 failed | 202 passed (211) ``` **Lint:** `oxlint packages/react-core/src/v2/hooks/` — `Found 62 warnings and 0 errors.` (all pre-existing exhaustive-deps warnings, none in the touched files). **Formatting:** `oxfmt --check` on the three source/test files — `All matched files use the correct format.` `oxfmt` does not process `.mdx`, so the reference page is out of its scope. **Public-API manifest:** no regeneration needed — `scripts/release/public-api/manifest.v1.json` records no type signatures and does not mention `useDefaultRenderTool` (`grep -c ReactElement` → `0`). ## Provenance Extracted from #5509 (@ataibarkai), which is 3915 commits behind `main` and being closed. That PR also changed `defineToolCallRenderer`'s schema default from `def.name === "*" && !def.args ? z.any() : def.args` to `def.args ?? z.any()`. **That change is deliberately not carried here** — it alters runtime behavior for named renderers declared without `args` (from `args: undefined` to `args: z.any()`) and deserves its own PR and its own verification. 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- This is an auto-generated comment: release notes by coderabbit.ai --> ## Summary by CodeRabbit * **New Features** * Custom renderers can now return `null` to suppress output when no UI should be displayed. * **Documentation** * Updated `useDefaultRenderTool` guidance to describe null-return behavior and selectively rendering tool calls. * **Tests** * Added coverage confirming null-render behavior and forwarded renderer properties. * Added compile-time validation for supported renderer return types. <!-- end of auto-generated comment: release notes by coderabbit.ai -->
Showcase Platform
Tagline: agent entry point for the showcase docs tree and from-scratch local setup. The fanout block below routes you to the right procedural doc.
Per-framework demos of CopilotKit (LangGraph, CrewAI, Mastra, Claude Agent SDK,
etc.). Each package is a Next.js frontend + agent backend bundled in a Docker
image. Railway deploys those images from main on push.
Agent Fanout — when X, see Y
| When you need to... | Read |
|---|---|
Turn a red cell green (cell red→green SOP, bin/showcase test CLI) |
./TESTING.md |
| Debug a failure mode locally (debugging loop, strategies, prod ops) | ./DEBUGGING.md |
Look up a framework / fixture / --isolate edge case |
./GOTCHAS.md |
| Add a brand-new integration (per-package + external setup) | ./INTEGRATION-CHECKLIST.md |
| Style a demo page (Tailwind v4, CopilotKit overrides, layout patterns) | ./STYLING-GUIDE.md |
| Reason about which shell renders what / consolidate a new frontend | ./FRONTEND-STRATEGY.md |
| Deploy / promote / pin / roll back a Railway service | ./RAILWAY.md (fleet config) + ./bin/README.md (bin/railway CLI) |
| Understand aimock fixture semantics (fixtures + Railway reconstruction) | ./aimock/README.md + ./aimock/RAILWAY.md |
| Operate showcase-harness (alerts, probes, hot reload, build/deploy) | ./harness/README.md + ./harness/docs/rotation-drill.md |
| Track or check per-slug deviations from canonical | ./integrations/<slug>/PARITY_NOTES.md |
Anything below is from-scratch local setup — skip if your stack is already up.
Layout
showcase/
bin/showcase # unified CLI — run showcase/bin/showcase <command> for help
bin/railway # Ruby tool for Railway ops (snapshot/promote/pin) — see bin/README.md
integrations/<slug>/ # one per framework (17 total) — Dockerfile, src/app/demos/*/, src/agents/ or equivalent
shell/ # hub: home page, /matrix, canonical /integrations/[slug]/[demo]/{preview,code}
shell-dashboard/ # internal-only feature × integration grid (port 3002)
harness/ # showcase-harness service — see harness/README.md
aimock/ # aimock fixtures + Railway config — see aimock/README.md
shared/
feature-registry.json # canonical features + categories (feeds the grid rows)
constraints.yaml # allowlist for which demos a package can expose
local-ports.json # deterministic host ports per package for local Docker runs
python/ typescript/tools/ # shared agent utility code; CI stages these into each build context
scripts/
dev-local.sh # low-level Docker Compose wrapper (prefer bin/showcase)
cli/ # command modules for bin/showcase
generate-registry.ts # builds shell/src/data/registry.json from all manifest.yaml
bundle-demo-content.ts # bundles per-demo source + README into shell/src/data/demo-content.json
docker-compose.local.yml # one service per package; ports from local-ports.json; env from .env
.env.example # commit template — copy to .env and fill in
Generated data files
The shell apps consume JSON data files that are generated at build time by
scripts in scripts/. These files are gitignored — every build path (Docker,
CI, npm run build, npm run dev) regenerates them automatically.
| File | Generator | Shell apps | What it does |
|---|---|---|---|
registry.json |
generate-registry.ts |
shell, shell-docs, shell-dojo, shell-dashboard | Integration manifest — scans integrations/*/manifest.yaml, builds the full catalog with metadata, feature flags, categories |
demo-content.json |
bundle-demo-content.ts |
shell, shell-docs, shell-dojo | Bundled source code from every demo directory — powers the Code tab, Snippet components, dojo cell viewer |
constraints.json |
generate-registry.ts |
shell | Filter facets for the integration explorer (categories, frameworks, features) |
search-index.json |
generate-search-index.ts |
shell, shell-docs | Cmd-K search entries — scans MDX docs, AG-UI content, and registry data |
starter-content.json |
bundle-starter-content.ts |
shell | Starter template source bundles for the "Get Started" code viewer |
docs-status.json |
probe-docs.ts |
shell-dashboard | Per-feature docs reachability — HTTP HEAD on og_docs_url, file-exists check on shell-docs MDX |
Each generator writes to the src/data/ directory of every shell app that
consumes it. Shell apps are independent — no shell cross-imports another
shell's data directory.
Prerequisites
- macOS or Linux
- Homebrew
- Docker engine. Any of: Docker Desktop, Colima (recommended, no GUI / no sign-in), or OrbStack.
- Node 22+ and npm (for
shell/shell-dashboarddev servers — they're not in the compose)
Colima install (one time)
brew install colima docker docker-buildx docker-compose
# Tell the docker CLI where its plugins live
mkdir -p ~/.docker
cat > ~/.docker/config.json <<'JSON'
{
"cliPluginsExtraDirs": ["/opt/homebrew/lib/docker/cli-plugins"]
}
JSON
# Start the engine (adjust resources to taste; needed for building 17 images)
colima start --cpu 4 --memory 8 --disk 60
# Verify
docker compose version
Colima auto-starts with brew services start colima if you want it on login.
API keys
One .env file feeds every container. Not committed.
cp showcase/.env.example showcase/.env
# Edit showcase/.env and fill in:
# OPENAI_API_KEY=<required>
# ANTHROPIC_API_KEY=<optional; needed for Claude Agent SDK demos and a few others>
# LANGSMITH_API_KEY=<optional; enables LangSmith tracing for LangGraph demos>
Only OPENAI_API_KEY is strictly required. Missing optional keys fail
gracefully (per-package).
bin/showcase CLI — quick reference
For the full invocation table (control-plane vs --direct, per-demo scoping
matrix) and the cell red→green SOP, see
./TESTING.md. For
debugging workflows (aimock rebuild cycles, fixture validation, probe testing,
diagnostics), see ./DEBUGGING.md.
# from any directory — paths resolved relative to the script itself
./showcase/bin/showcase up langgraph-python # start infra + one integration
./showcase/bin/showcase test langgraph-python --d5 --isolate # run D5 probes (canonical)
./showcase/bin/showcase down # tear down
| Command | Description |
|---|---|
test <slug> |
Run probes against a running service (see TESTING.md for full flag table) |
up [slugs...] |
Start infra (aimock, pocketbase, dashboard) + named packages. No args = infra only |
down [slugs...] |
Stop services. No args = stop everything |
build [slugs...] |
Build Docker images |
rebuild <slug> |
Rebuild a slug (handles symlink deref that raw docker build cannot) |
recreate <slug> |
Force-recreate a service (picks up new image) |
restart <slug> |
Restart container (picks up src/ edits — see Iterating on a demo below) |
ps |
Show running services |
ports |
Print slug to host port mapping |
logs <slug> |
Follow container logs (supports --grep, --since, -n, --no-follow) |
doctor |
Check local environment and stack health |
Container exposes port 10000 internally → host port in
shared/local-ports.json. The image and entrypoint
are the same ones Railway runs.
Hooking local containers into the shell
The shell app's /preview route iframes integration.backend_url (Railway)
by default. Set SHOWCASE_LOCAL=1 when running shell to swap in the
localhost ports from local-ports.json instead — per-slug, falling back to
Railway for anything you don't have running.
cd showcase/shell
npm install # once
SHOWCASE_LOCAL=1 npm run dev # /preview iframes http://localhost:<port>/demos/...
In production the env var is unset → Railway URLs, unchanged.
shell-dashboard — feature × integration matrix
Internal overview of which packages support which features, linking to the
canonical /preview and /code routes on shell. Lives at
http://localhost:3002 and reads the same registry.json shell does.
cd showcase/shell-dashboard
npm install
npm run dev
Column ordering lives in shell-dashboard/src/lib/sort-order.ts — internal to
this app, not part of the public registry.
Iterating on a demo
- Edit the demo in
integrations/<slug>/src/app/demos/<demo-id>/page.tsx(and the backend undersrc/agents/if applicable). - Rebundle so
/codeinshellreflects the edit:cd showcase && npx tsx scripts/bundle-demo-content.ts. - If you changed
manifest.yamlor added a feature toshared/feature-registry.json:npx tsx scripts/generate-registry.ts. - Rebuild + restart the container:
showcase/bin/showcase up <slug>(orrestart <slug>for puresrc/edits — see DEBUGGING.md "Dev Iteration Speed"). - The grid in
shell-dashboardand/previewinshellnow show the new state.
Relationship to Railway
- Dockerfile,
entrypoint.sh, and build context (shared_python/,shared_typescript/) are shared between local and Railway. .github/workflows/showcase_deploy.ymlbuilds each image on push tomainand pushes it to Railway. Per-PR deploys are opt-in viagh workflow run showcase_deploy.yml -r <branch> -f service=<slug>.- The only real differences at runtime are env var values and the URL. If something works locally in Docker, it works on Railway (and vice versa).
Dashboard SOPs (catalog.json + PocketBase)
The dashboard at showcase.copilotkit.ai reads two data sources:
- Static
catalog.json— generated at build time bypnpm generate-registry. Contains the full 38-feature × 17-integration cell matrix with status (wired/stub/unshipped), parity tiers, and feature categories. Changes require a generator run + commit. - Live PocketBase probe results — streamed via SSE. Probes discover demo routes automatically and update the dashboard in real time. No manual intervention needed for probe data.
Known limitation — PocketBase fetch cap: useLiveStatus.ts fetches status
records with a hard INITIAL_CAP (currently 2000). PocketBase returns records
in rowid (creation) order. If the total record count exceeds the cap,
later-created dimensions (e.g. e2e:<slug>/<featureId> per-cell records from
the 6-hourly e2e-demos probe) get silently truncated, causing the dashboard to
show D2 instead of D4 across the board. If new probe types are added and the
dashboard regresses to D2, raise INITIAL_CAP in
shell-dashboard/src/hooks/useLiveStatus.ts. The correct long-term fix is
dimension-scoped fetching or sort=-updated so the cap never silently drops
functional records.
Key invariants:
- Parity tiers are never manually set. They are computed by comparing each integration's wired feature set against the reference integration's.
- The reference integration is auto-detected as the integration with the
most wired features (ties broken alphabetically). No
reference: trueflag exists. catalog.jsonis gitignored — the generator emits it into the shell apps'src/data/directories, which are already in.gitignore.- The
stubstatus means: feature declared in manifest, demo entry exists, but noroutefield. Today onlylanggraph-python/cli-startqualifies.
SOP 1: Wire a new demo on an existing integration
- Edit
showcase/integrations/<slug>/manifest.yaml— add the feature tofeatures[]and a correspondingdemos[]entry with aroute. - Run
pnpm generate-registry— updatesregistry.jsonANDcatalog.json. The cell flips fromunshippedtowired. Parity tiers auto-recompute. - Commit the manifest + both generated files. PR, merge.
- CI rebuilds the package image + dashboard image. Railway auto-deploys both.
- Ops probes discover the new demo route and begin probing. Dashboard updates live via PocketBase SSE — no further action needed.
SOP 2: Code fix on an existing demo (no manifest change)
- Edit code under
showcase/integrations/<slug>/src/.... - PR, merge. No generator run needed (manifest unchanged).
- CI rebuilds the package image. Railway auto-deploys.
- Probes re-probe on the next tick. If the fix turns a red cell green, the dashboard updates live. Zero manual steps beyond the normal PR workflow.
SOP 3: Add a brand-new integration
- Create
showcase/integrations/<new-slug>/manifest.yamlwithfeatures[]+demos[]. - Add
{"slug": "<new-slug>", "name": "<Display Name>"}toshowcase/shared/packages.json. - Provision a Railway service (manual:
railway service createor Dashboard UI). - Run
pnpm generate-registry— catalog gains 38 new cells (mostlyunshipped, somewired). Parity tier computed automatically. - Commit, PR, merge. CI + Railway deploy. Probes discover the new service automatically via the Railway discovery filter.
For the full per-package + external-setup checklist see
./INTEGRATION-CHECKLIST.md.
SOP 4: Reference migration (move the reference integration)
- No manual flag needed — the generator auto-detects the reference as the integration with the most wired features (ties broken alphabetically).
- If you want a different integration to be reference, wire more features on it until it leads the count.
- Run
pnpm generate-registry— all parity tiers recompute automatically. - Commit, PR, merge.