Carrick

Carrick is a live, type-aware, intent-aware cross-repo index of every TypeScript service in your GitHub org, exposed to AI coding agents over the Model Context Protocol.

Carrick scans TypeScript projects using npm, pnpm, Yarn, Bun, or Deno. Deno projects require Deno 2.9.4 or newer; the Action supplies the runtime and reads existing deno.json or deno.jsonc manifests. Dependency preparation disables lifecycle scripts (details). Cross-repo features need at least two services indexed in the same Carrick project; a single-service install still gets same-repo validation.

Get started: sign up at app.carrick.tools · full documentation at docs.carrick.tools

What an agent can ask

Connect Claude Code, Cursor, Windsurf, or Codex to the Carrick MCP endpoint. Carrick answers semantic questions about your org that an agent normally has to grep across repos to answer, badly:

• "Which functions handle webhook signing across our services?"
• "Where do we deduplicate users by email?"
• "What calls /api/users and what response shape do they expect?"
• "Show me every function that retries on rate-limit errors."

These work because the index combines structural facts, resolved types, and a per-function description of what the code actually does.

What's in the index

For every scanned function in every repo in your org, Carrick stores three layers:

• Structural. Endpoints declared, outbound calls made, mounts, normalised paths.
• Type-aware. Request and response types resolved through the TypeScript compiler, so cross-repo type compatibility is checkable.
• Intent-aware. A one or two sentence description of what each function does, generated at scan time and stored alongside the structural and type data.

The intent layer is the difference. It is what lets an agent answer "where do we deduplicate users by email" rather than "which functions are named dedupeUser."

Connect your agent

The MCP endpoint lives at https://api.carrick.tools/mcp.

claude mcp add --scope user --transport http carrick https://api.carrick.tools/mcp

The recommended authentication is sign-in-with-Carrick: your agent opens a browser, you click Approve once, and no API key changes hands. A manual key paste is available as a fallback. To get started, sign up at app.carrick.tools — the full setup guide lives at docs.carrick.tools.

Populate the index

The index is populated by running the Carrick GitHub Action on each TypeScript repo you want indexed. On the main branch the action refreshes that repo's contribution to the index. On pull requests the Carrick App posts a drift comment for you (no extra workflow steps required).

name: Carrick

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
  # Lets Carrick re-trigger this repo's main scan when a sibling repo in the
  # project changes. Optional today and dormant unless enabled server-side —
  # included here so it's already wired if you ever turn it on.
  repository_dispatch:
    types: [carrick-sibling-updated]

permissions:
  id-token: write
  contents: read

jobs:
  carrick:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        # Full git history lets Carrick diff against the last scan and run incrementally.
        with:
          fetch-depth: 0

      - uses: carrick-tools/carrick@v1

No secrets required. The id-token: write permission lets the action mint a short-lived GitHub Actions OIDC token, which Carrick uses to verify the repo's identity and authorize the upload. On pull requests the Carrick App posts the drift comment itself, so the workflow needs no extra permissions and no comment-posting step. Just make sure the Carrick GitHub App is installed on the org and the repo is connected to a project in the dashboard.

Pull requests opened from forks are skipped gracefully: GitHub withholds OIDC credentials from fork runs, so the action prints a notice and exits successfully instead of failing the check. The scan runs when a maintainer pushes the branch to the repository itself.

Dependencies

Package types need their dependencies on disk. Node projects use installed node_modules, and Deno projects use the Deno dependency cache. The Action prepares those dependencies before analysis:

• For Node projects, installation runs when a lockfile sits at the path being analyzed. The lockfile picks the manager: package-lock.json runs npm ci, pnpm-lock.yaml runs pnpm install --frozen-lockfile, yarn.lock runs yarn install, bun.lock/bun.lockb runs bun install.
• Lifecycle scripts are disabled in every case, so nothing in your repo executes during a scan.
• Each install command has a five-minute timeout. A failed or timed-out install prints a warning, and analysis continues with the available dependencies; missing type prerequisites are reported by the scanner.
• Existing node_modules skips the Node install. A Deno manifest at the scan root still triggers Deno cache preparation. In a monorepo preparation happens at the path being scanned.
• The package manager's download cache is restored between runs, keyed on the lockfile's hash.

For Deno roots the Action runs deno install --frozen --node-modules-dir=none. This prepares the Deno dependency cache and prevents npm lifecycle scripts from running even when the project authorizes them through allowScripts. A root with both Node and Deno configuration prepares both dependency stores. Before local indexing, install Deno 2.9.4 or newer and run the same preparation command from the Deno workspace root. Projects that import generated declarations must generate those declarations through their normal build before indexing.

Deno services normally omit tsconfig and use their nearest Deno manifest. An explicit ordinary TypeScript config selects the TypeScript path. An explicit Deno config must name that nearest manifest; deno.json takes precedence over deno.jsonc when both exist. Import maps must be local files. Nested Deno roots without a Deno manifest at the Action's scan root need dependency preparation in their own workspace before the Carrick step.

Turn it off with:

      - uses: carrick-tools/carrick@v1
        with:
          install-dependencies: false

Private registries use your own credentials. Carrick adds no auth of its own: put the token your .npmrc reads in the job's environment and the install step inherits it.

      - uses: carrick-tools/carrick@v1
        env:
          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

Re-analyzing everything

A scan reads the model once per changed file and reuses what it already has for the rest, which is what makes a routine scan cheap. Occasionally the answers themselves need redoing rather than the files: Carrick starts extracting something it did not extract before, and the cache holds answers from before it could. full-scan re-analyzes every file for one run.

Ask for it, rather than leaving it on. Wire it to the workflow's workflow_dispatch input, which is what carrick init scaffolds:

on:
  workflow_dispatch:
    inputs:
      full-scan:
        type: boolean
        default: false

jobs:
  carrick:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - uses: carrick-tools/carrick@v1
        with:
          full-scan: ${{ inputs.full-scan }}

Then run it from the Actions tab, or:

gh workflow run carrick.yml -f full-scan=true

On every other trigger the expression is empty and the incremental scan runs exactly as before.

An ordinary scan indexes a commit once per scanner version, so a second run on an unchanged commit stores nothing and says so. A full scan is the exception: its answers replace what the index holds for that commit, because re-analyzing everything is a statement that the stored answers were the stale part.

MCP tools

The MCP endpoint exposes the index as structured tools your agent can call directly.

Tool	Purpose
search_by_intent	Find functions by what they do — a plain-English query matched against the intent descriptions
list_projects	The Carrick projects in your workspace and each project's connected repos
list_services	Every service Carrick has indexed in your org
list_function_intents	One or two sentence descriptions of indexed functions, searchable by service
get_api_endpoints	Endpoints declared by a given service
get_endpoint_types	Resolved request and response types for a specific endpoint
get_type_definition	Fully resolved TypeScript type by name, across the org
get_service_dependencies	Services that call a given producer
check_compatibility	Whether service A's call to service B matches the producer's contract
scaffold	Generates the files to onboard a repo: the GitHub Actions workflow, an agent guide, and a carrick.json skeleton

On pull requests

On pull requests the Carrick App posts a comment summarising drift detected against the indexed services: type mismatches between producers and consumers, mismatched HTTP verbs, missing or orphaned routes, and npm-dependency-version conflicts. It updates the same comment in place on each push to the PR. PR comments are on by default for new projects and can be toggled per project in the dashboard; PR runs never alter the index.

Configuration

Add a carrick.json to each indexed service to help classify outbound calls.

{
  "serviceName": "order-service",
  "internalEnvVars": ["USER_SERVICE_URL", "INVENTORY_API"],
  "externalEnvVars": ["STRIPE_API", "GITHUB_API"],
  "internalDomains": ["https://api.yourcompany.com"],
  "externalDomains": ["https://api.stripe.com", "https://api.github.com"]
}

Field	Description
serviceName	Friendly name for this service
internalEnvVars	Env vars pointing at other services in your org. Calls are validated against the index.
externalEnvVars	Env vars pointing at third-party APIs. Calls are ignored.
internalDomains	Full URL prefixes for internal services
externalDomains	Full URL prefixes for third-party APIs to ignore

When Carrick sees a call like fetch(process.env.ORDER_SERVICE_URL + '/orders'), it needs to know whether ORDER_SERVICE_URL points internally or externally. Unclassified env vars surface as a configuration suggestion in the PR comment.

Monorepos

carrick.json is optional. Without it, Carrick derives services from npm or pnpm workspace manifests; a plain repo is one service. An explicit config takes precedence over derivation. To set service boundaries and shared source includes, declare a services array. Each entry is scanned independently and indexed as its own service:

{
  "includes": {
    "lambdas/_shared": {
      "externalEnvVars": ["GITHUB_API_BASE"],
      "externalDomains": ["https://api.github.com"]
    }
  },
  "services": [
    {
      "name": "check-or-upload",
      "directory": "lambdas/check-or-upload",
      "include": ["lambdas/_shared"],
      "internalEnvVars": ["CARRICK_API_ENDPOINT"]
    },
    {
      "name": "dashboard",
      "directory": "app",
      "tsconfig": "tsconfig.json"
    }
  ]
}

Field	Description
name	Service name (alias for serviceName inside a services entry)
directory	Service root, relative to carrick.json. Files outside every declared directory are ignored
include	Extra source roots to pull in for type/function resolution (e.g. shared libraries copied in at build time), relative to carrick.json
tsconfig	Optional TypeScript config path, relative to directory. Deno services normally omit this field and use their nearest Deno manifest

Alongside services, the optional top-level includes map declares classification for a shared source root once. See Declaring a shared root once.

Each service also accepts the call-classification fields (internalEnvVars, externalEnvVars, internalDomains, externalDomains). When services is present, any sibling top-level flat fields are ignored. Cross-service drift, dependency conflicts, and duplicate intents are detected between the declared services just as they are across repositories.

Declaring a shared root once

When several services reach a third-party API through the same shared directory, the calls belong to that directory, not to each service that pulls it in. The optional top-level includes map declares classification per shared source root:

{
  "includes": {
    "lambdas/_shared": {
      "externalEnvVars": ["GITHUB_API_BASE"],
      "externalDomains": ["https://api.github.com"]
    }
  }
}

Each key is a source root spelled as a service names it in its include (a leading ./ and a trailing / are ignored when matching). Each value takes the same four classification fields a service takes.

Every service whose include lists that root inherits those declarations, unioned with its own. A service keeps everything it declares itself, and a name declared in both places appears once. A service that does not include the root inherits nothing.

A key that no service lists in its include fails the scan rather than doing nothing, so a mistyped root is reported instead of leaving the calls unclassified.

How it works

1. SWC parses each TypeScript file into an AST.
2. A static-analysis pass extracts function exports, mounted routers, pattern-matched HTTP calls, GraphQL schemas and operations, and WebSocket event contracts.
3. An LLM agent handles the cases pattern matching can't reach: dynamic URLs, factory functions, framework-specific routing.
4. A TypeScript sidecar resolves request and response types against the actual TypeScript compiler.
5. A second LLM pass writes the per-function intent description.
6. The org index lives in DynamoDB and S3 and refreshes each time a service's main branch runs.

License

Elastic License 2.0. Copyright (c) 2026 Far Harbour B.V.

Development

See AGENTS.md for build, test, and contribution conventions.

cargo test
cargo fmt
cargo clippy

Install the optional pre-commit hook to run formatting and tests before each commit:

./scripts/install-hooks.sh