Concave

Scope

Use this skill for Concave-specific behavior and Concave-vs-Convex differences in this repo.

Use concave-parity when the task is specifically about parity gaps, local workarounds, or removing Concave-specific bandaids after upstream catches up.

Keep the boundary hard:

• public kitcn CLI supports backend: "concave" and --backend concave
• public kitcn CLI still defaults to Convex
• /example stays on Convex
• the big convex-test suites stay on Convex tooling
• Concave is both a real kitcn backend and the repo's preferred agent/CI runtime lane

Do not restate generic Convex docs here. The convex skill already owns that.

Upstream Concave Facts That Actually Matter

These are the Concave-only facts worth keeping in your head.

Runtime model

• Concave is Convex-compatible, self-hosted, and multi-runtime.
• Supported runtimes marked production upstream:
  • Cloudflare Workers
  • Bun
  • Node.js
• Bun is the default local runtime.
• Node.js requires 22.5+ and --experimental-sqlite.
• Cloudflare is the recommended production target.

Deployment shape

• Cloudflare uses Workers + Durable Objects.
• DO SQLite is the default document store on Cloudflare.
• D1 is optional when you need different scaling characteristics.
• R2 is only needed for ctx.storage.
• Self-hosted Bun/Node and desktop embeddings are single-instance by default because SQLite needs exclusive file access.
• concave build can compile a standalone Bun-based binary; useful, but still single-instance with SQLite.

Local dev shape

• concave dev auto-picks runtime; --bun, --node, and --cf force it.
• alpha.14 defaults local dev to 3210.
• Bun/Node local data lives in ./.concave/local.
• Bun dev binds 0.0.0.0 by default. That is LAN-visible. 127.0.0.1 is the safer local-only bind.
• Local dashboard lives at /_dashboard.
• DevTools are web-only and designed around Vite/manual client init, not React Native.

Configuration / API differences

• concave.config.ts is real Concave surface area.
• convex.json works now. That matters here because kitcn already uses it.
• Bun/Node use createConcave(...).
• Cloudflare uses explicit defineConcaveRuntime(...) wiring.
• Adapter choice is part of the product, not hidden infra:
  • docstore
  • blobstore
  • module loading
  • Cloudflare bindings

Compatibility gaps

• Vector search is only basic/brute-force in built-in adapters.
• Crons are planned, not done.
• Convex Auth is not supported.
• Streaming exports are not supported.

Testing stance upstream

• convex-test is still valid for isolated function/unit tests.
• Real E2E against Concave is done with createConcave(...) plus ConvexHttpClient.
• Cross-runtime E2E is a real supported testing strategy upstream.

Current Repo Usage

We use Concave in two concrete ways.

Public backend selector

kitcn now resolves backend in this order:

1. --backend <convex|concave>
2. meta["kitcn"].backend in concave.json
3. default convex

Public meaning:

• convex => drive Convex CLI
• concave => drive Concave CLI

Internal meaning:

• public concave currently maps to the Bun adapter (concave-bun)

Files:

• packages/kitcn/src/cli/config.ts
• packages/kitcn/src/cli/core.ts
• packages/kitcn/src/cli/cli.ts

Command shape:

• kitcn orchestration commands (init, dev, codegen, deploy, migrate, aggregate, reset) run on the selected backend
• unknown commands pass through to the selected backend CLI
• kitcn env sync stays a kitcn helper
• raw kitcn env ... passthrough is Convex-only because Concave has no matching upstream env command

Concave smoke lane

Use:

bun run test:concave

Files:

• test/concave/run-smoke.ts
• test/concave/fixture/**

Runtime shape:

• createConcave(...)
• SqliteDocStore(':memory:')
• ConvexHttpClient

Goal:

• generated kitcn runtime contract loads
• one mutation/query roundtrip works end-to-end

Keep it small. This is a smoke lane, not a migration plan.

Repo-Specific Concave Differences

Template sync/check uses the public backend selector

tooling/fixtures.ts runs local committed starter sync with kitcn init -t <next|vite> --backend concave.

That means:

• committed fixtures/*/convex/functions/_generated/* comes from the create flow running kitcn codegen against Concave-backed bootstrap
• template-mode Concave codegen intentionally uses concave codegen --static
• tooling/fixtures.ts itself must not shell out to raw kitcn codegen

_generated/* drift is expected

Concave-generated _generated/* output is not guaranteed to match Convex-generated output byte-for-byte.

Read the diff before calling it a bug.

staticDataModel mismatch is still real

Current repo finding:

• fixtures/next/convex.json sets codegen.staticDataModel: true
• Concave-generated fixtures/next/convex/functions/_generated/dataModel.d.ts is still dynamic

So today, in this repo path, Concave is not honoring that flag.

api.d.ts override is gone

Current repo truth:

• alpha.14 emits the same api.d.ts shape our old source-backed override used to force
• kitcn no longer post-writes _generated/api.d.ts

Meaning:

• if api.d.ts drifts again, treat it as a fresh upstream regression
• do not quietly resurrect the old overwrite helper

Use plain bun, not bun test, for the smoke lane

Root bun test preloads Happy DOM here. That poisoned ConvexHttpClient behavior for the Concave smoke lane.

Keep the smoke entry as:

bun ./test/concave/run-smoke.ts

Keep the adapter tiny

Do not invent a second fake runtime layer on top of backend.

The right model is:

• one public selector: backend
• one internal mapping: concave -> current Bun adapter
• native backend flags stay native

Read Before Editing

Start with repo wiring:

• packages/kitcn/src/cli/backend-core.ts
• packages/kitcn/src/cli/commands/init.ts
• packages/kitcn/src/cli/commands/init.test.ts
• tooling/fixtures.ts
• tooling/fixtures.test.ts
• tooling/scenarios.ts
• tooling/scenarios.test.ts
• test/concave/run-smoke.ts
• test/concave/fixture/**
• .github/workflows/ci.yml

Then read Concave docs starting from:

• https://docs.concave.dev/llms.txt

Do Not

• do not add a second selector like --runtime concave
• do not switch /example to Concave
• do not migrate the big convex-test suites just because Concave exists
• do not document generic Convex APIs here
• do not assume Concave codegen output equals Convex codegen output

Verification

When touching Concave repo-runtime wiring, run:

bun test packages/kitcn/src/cli/commands/init.test.ts ./tooling/fixtures.test.ts ./tooling/scenarios.test.ts
bun test packages/kitcn/src/cli/cli.test.ts
bun run test:concave
bun run fixtures:check
bun run scenario:check

If package code changed too, also run:

bun --cwd packages/kitcn build
bun lint:fix
bun typecheck

Skill Sync

When Concave docs or repo usage changes, update this skill with this exact loop.

1. Re-read current repo wiring

rg -n "backend|concave-bun|test:concave|createConcave|@concavejs|Concave|--backend" \
  package.json \
  packages/kitcn/src/cli/backend-core.ts \
  packages/kitcn/src/cli/config.ts \
  packages/kitcn/src/cli/cli.ts \
  packages/kitcn/src/cli/commands/init.ts \
  packages/kitcn/src/cli/commands/init.test.ts \
  tooling/fixtures.ts \
  tooling/fixtures.test.ts \
  tooling/scenarios.ts \
  tooling/scenarios.test.ts \
  test/concave \
  .github/workflows/ci.yml \
  -g '!**/_generated/**'

2. Re-fetch the upstream Concave doc index

mkdir -p /tmp/concave-docs-fetch
curl -fsSL -A 'Mozilla/5.0' https://docs.concave.dev/llms.txt \
  | tee /tmp/concave-docs-fetch/llms.txt

3. Re-fetch every linked page from llms.txt

awk '
  match($0, /(https:\\/\\/docs\\.concave\\.dev[^) ]+)/, m) { print m[1] }
' /tmp/concave-docs-fetch/llms.txt \
  | nl -ba \
  | while read -r n url; do
      curl -fsSL -A 'Mozilla/5.0' "$url" >"/tmp/concave-docs-fetch/${n}.md"
    done

4. Rewrite this file with Concave-only facts

Rules:

• keep only Concave-specific behavior or Concave-vs-Convex differences
• keep repo-specific usage and mismatches
• do not restate generic Convex docs

5. Regenerate agent docs

bunx skiller@latest apply

6. Validate the skill wiring

bun run intent:validate
bun run intent:stale

If .claude/AGENTS.md changes, that is expected. It is generated from .claude/**.