Checktrail MCP Server

Checktrail

Local code validation with a CLI, MCP tools, and evidence of what actually ran.

Formerly Repo Verifier. See the rename guide for existing source checkouts.

Published preview: 0.1.0-alpha.5. Public source is available at stsepelin/checktrail. See implementation status, the plan and the language matrix before relying on an adapter. Installation covers the CLI, Claude Code and Codex. Agent skills provides setup, validation and review workflows installable with npx skills add stsepelin/checktrail. Project setup covers init, doctor and MCP configuration generator. Release preparation records publication and verification gates. The milestone audit separates implemented profiles from open acceptance work; client checks record actual application coverage. Public adoption records the published package on five pinned libraries, including setup friction and compatibility gaps. Alpha.3 fixes the recorded TypeScript 4.9.5 incompatibility. The setup scope guide explains language, documentation and workflow coverage. Alpha.5 adds named Go build-tag profiles with per-check exclusions. Its release record includes package, client and upgrade/rollback verification.

The hosted matrix passed at release commit 832a044 on Linux and macOS. The exact npm tarball and fresh CLI/MCP installations were verified. The MCP Registry entry is active; execution remains disabled by default.

Checktrail discovers projects, plans registered checks, invokes native tools when explicitly trusted, and reports results without turning skipped or empty checks into success. The same engine serves developers, CI and MCP clients.

The optional library task store retains local validation results across restarts. A library worker adds native execution, polling and cancellation. MCP reports still use memory; standard Tasks integration remains pending.

Try the local checkout

Requires Node.js 22 or newer. Execution currently targets macOS and Linux.

npm ci --ignore-scripts
npm run build
node dist/src/cli.js plan --root examples/javascript --detailed
node dist/src/cli.js run --root examples/javascript --trust-project --detailed

plan and inspect read files without executing project code. run requires --trust-project: tests, compiler plugins and project configuration can execute code with your user privileges. This is not a sandbox.

Successful commands return JSON except help/version; input errors use stderr. Exit codes:

A passing run applies to the selected checks and scope only. PHP syntax passing does not imply its application tests passed. Unknown frameworks and empty plans are incomplete. A source change during validation prevents an aggregate pass.

Initial adapters

Tools must already be installed. No dependency installation, automatic fixes, service startup, migrations, commits or deployments are performed by the engine. Go execution disables module proxy downloads and toolchain auto-downloads. The Rust profile uses locked offline Cargo and disables rustup auto-installation. Other invoked tools and test code can still access the network.

Select checks

Without configuration, registered defaults apply to each detected project. Node tests are selected automatically only for the exact script node --test. Python needs an explicit selection because a manifest does not identify a runner. Create checktrail.json in the inspected root:

{
  "schemaVersion": 1,
  "projects": [
    { "path": "web", "checks": ["javascript.node-test", "javascript.eslint"] },
    { "path": "library", "checks": ["javascript.typescript"] },
    { "path": "service", "checks": ["go.format", "go.vet", "go.test"] },
    { "path": "worker", "checks": ["python.unittest"] }
  ]
}

When present, this file selects only the listed projects/checks. Paths are exact discovered project roots relative to --root; use . for that root itself. Configuration cannot supply arbitrary commands or enable execution permissions. The schema rejects unknown fields and check IDs are validated by the engine. Private configuration and rules need not be published. Local public/private JSON packs and additive operator overlays are implemented; see policy packs. An explicit fetch-pack command can download a pinned data-only pack over HTTPS for later offline use.

Operator-registered external adapters can run a pinned local Node, Python, PHP or native executable bundle. Repository configuration can select their registered checks; execution still requires operator trust. The protocol checks evidence completeness, while the adapter author remains responsible for the correctness of its analysis.

The TypeScript check requires a local tsconfig.json and an installed compiler inside the configured root (project-local or hoisted to an ancestor). It disables noCheck, emission and incremental state. Every inventoried .ts, .tsx, .mts and .cts file in that project must appear in the compiler's file list. A clean compiler exit with excluded source is incomplete. Other compiler options, including strictness and declaration checking, come from the project config. Use javascript.typescript-build for project-reference solutions with fresh in-memory declarations. Vue SFC checking uses its separate adapter. TypeScript 6.0.3 is exercised in integration tests; other versions are unverified.

javascript.vue-router captures a selected native testing router and verifies complete record participation in declared URL probes; see the Vue Router profile for versions and projection limits. javascript.nuxt-runtime builds a fresh SSR testing assembly and checks native router capture after in-process requests; see the Nuxt profile. python.fastapi-routes captures a configured FastAPI application's supported flat route table after lifespan startup and detects exact duplicate registrations. See the FastAPI profile for native versions and scope limits. python.django-routes captures supported nested URL resolver chains after Django setup; see the Django profile. php.laravel-runtime captures the testing assembly's routes, middleware, listeners, schedules and container binding projection. Compare inventories to detect wiring changes; see the Laravel profile for bootstrap behavior and limits.

javascript.eslint uses an installed ESLint and a project-local JavaScript flat config. Ignored files, unmatched configuration and files with no enabled rules make the check incomplete. Errors and warnings fail it. It preserves existing lint caches and performs no fixes. See the ESLint contract for scope, configuration requirements and verified tool support.

javascript.vitest runs an installed Vitest once, requires each planned test file in the report, and rejects empty/all-skipped results. It disables focused tests, snapshot updates and automatic dependency installation. See the Vitest contract for tested versions and limitations.

javascript.playwright reconciles native tests, projects and retry outcomes, requires preinstalled browsers, and protects snapshots. See the Playwright contract.

javascript.jest requires native assertion and file accounting and treats pending tests conservatively as incomplete. See the Jest contract. javascript.vue-tsc checks Vue SFCs and TypeScript without emitting output, and rejects disabled template checking. See the Vue contract.

python.pytest reconciles native collection and setup/call/teardown evidence. See the pytest contract for scope and prepared runtimes.

python.ruff requires exact native file selection and active-rule evidence, with fixes disabled. See the Ruff contract.

python.mypy checks explicit source with native source-count evidence and rejects broad module-error suppression. See the mypy contract.

go.test-race adds opt-in native race instrumentation with uncached test evidence. See the Go race contract. Go checks reconcile native package selection with inventoried source; go.staticcheck adds explicit all-rule analysis and normalized findings. See Go scope. The constrained go.golangci-lint profile accepts explicit native linter selection while disabling hidden issue filters and fixes. Alpha.5 adds Go build-tag profiles with one explicit configuration per selected native check. Alpha.4 does not include this capability; a runnable example is in examples/go-build.

php.phpstan combines per-file analysis accounting with native JSON diagnostics. See the PHPStan contract.

php.phpunit streams fresh native JUnit evidence with file and assertion accounting. See the PHPUnit contract. Existing JUnit artifacts can also be imported separately; import does not verify current source or execution freshness.

php.pest runs focused siblings in CI mode and disables cached test-impact replay; see Pest. php.pint validates formatting with native file and rule accounting; see Pint.

Detailed reports include normalized source findings for ESLint, Ruff and PHPStan, Staticcheck, golangci-lint and TypeScript solution builds. SARIF export preserves failures and incomplete execution without treating an empty findings list as success.

Projects can declare environment requirements, supplied only through operator --allow-env NAME permissions or explicit library options. MCP tool calls cannot grant environment access.

Use workspace dependencies and Git selection with --base REVISION to validate changed projects and their declared consumers. Uncertain impact retains the full configured plan.

MCP

Run the server from the built checkout:

node dist/src/cli.js serve --root /path/to/your/repository

For a client that accepts a command/arguments server definition:

{
  "mcpServers": {
    "checktrail": {
      "command": "node",
      "args": [
        "/path/to/checktrail/dist/src/cli.js",
        "serve",
        "--root",
        "/path/to/your/repository"
      ]
    }
  }
}

The available tools are project_context, validation_plan, validation_run, validation_report, finding_comparison, runtime_comparison, contract_validation, architecture_validation, review_guidance, review_context, review_receipt, and mutation_experiment. The first two currently return the same project/check inventory; advisory guidance and source review use their separate tools. Reports are kept in memory (the latest ten) and disappear when the process exits.

Add --allow-execution to server arguments only for trusted project execution. The model cannot grant that permission through a tool argument. Add --detailed only if the client may receive paths, commands and raw diagnostics. The default summary omits those fields. Data returned through an MCP client may be sent to that client's model provider.

The implementation uses the official MCP v2 SDK. Automated tests exercise the 2026-07-28 protocol and the SDK's legacy negotiation over stdio. This does not establish compatibility with every editor or agent application.

Validation runs asynchronously and supports cancellation, but returns its report on the original tool call. The optional durable Tasks extension is not implemented. See MCP compatibility for lifecycle tests, the reproduced SDK routing limitation and the remaining Tasks work.

Exact finding baselines and exceptions are available through the CLI, library and MCP. Finding policy describes creation, expiration, staleness and expansion checks. A successful comparison retains the separate native validation outcome; it never changes a failed validation into a pass.

Runtime inventory comparison checks local before/after assembly artifacts for changed registrations, attributes, duplicates and order. Imported artifacts retain explicit completeness and provenance limits.

Public policy packs and private overlays compose registered checks with pinned SHA-256 integrity. Use --policy-overlay at CLI invocation or MCP startup for local additions to checked-in requirements.

Captured contract checks validate producer JSON against strict consumer schemas, with worker deadlines and separately labeled imported evidence.

Limits and evidence

Detailed reports include tool identity evidence. Native version probes share execution limits and require operator trust; missing identity prevents a successful check from being reported as passed.

Inventory excludes dependency/build directories, symlinks and common secret-file names. It does not apply .gitignore. Optional Git selection retains these exclusions. Limits are 20,000 entries, depth 32, 8 MiB per file and 64 MiB total file bytes. A source fingerprint covers included contents and exclusion names, not ignored dependencies, external configuration, tool binaries or services.

Execution has a run-wide time budget (30 seconds by default, configurable up to 120 seconds), 1 MiB output per command and 4 MiB across a run. Timeouts, cancelled work, truncated output and malformed test evidence are incomplete. Detailed reports include process output; do not publish reports from private repositories.

Results are not proof against malicious project code: a trusted test can forge output, alter other files or start detached processes. Isolation and attestation are separate future capabilities. See security.

Development

npm run check
npm run format:check
node scripts/smoke-package.mjs

Tests include real process execution, native adapter integration where tools are available, source-change detection, output limits, schemas, CLI exit codes and MCP calls. Missing native tools are explicitly skipped locally; CI prepares tools and requires exact native regression names through required profiles. Run node scripts/generate-schemas.mjs after building when changing schema definitions; tests reject drift in the checked-in JSON schemas.

All examples and fixtures are synthetic. Contributions must include a minimal broken case, its fix, and a valid near miss where applicable. See contributing. Licensed under MIT.

Explicit architecture policies check captured project dependencies against literal layer allowlists and optional cycle restrictions. Imported graph completeness is declared evidence; native import discovery is not implied. The public built-package fixture exercises an installed producer through consumer type and runtime checks.

Advisory review assistance

Use guidance --root PATH for public review questions selected from planned checks, or add an explicit --topic. This read-only operation makes no coverage claim and invokes no model. See guidance.

Use mutate --root examples/mutations --input mutations.json --trust-project for a bounded experiment in temporary source copies. Its initial profile supports flat Node tests in dependency-free projects. Assertion kills, survivors and inconclusive execution are separate advisory results; see mutation experiments.

The C/C++ profile validates prepared Clang argument arrays and requires native dependency coverage for inventoried translation units and headers. It does not run build systems, generate missing headers, link or execute tests.

The Java profile compiles inventoried sources with an explicit release and pinned local dependencies. Maven/Gradle, annotation processors and application tests are not executed.

Reproduce synthetic planning and execution costs with the performance harness. Reports retain raw measurements and artifact identities; the documented snapshots are observations, not speed guarantees.

The C# profile uses a prepared .NET SDK and explicit compilation settings. Project build targets, source generators and test runners are separate capabilities.

The GitHub Actions profile checks inventoried workflows with explicit runner labels and variables, local dependency checks and native completion evidence. It does not execute workflow jobs or action code.

Development evaluation records per-family detection, false-positive and incomplete-result counts against direct native commands. These small synthetic observations do not establish independent review quality. The agent evaluation workflow freezes public-source cases, separates native-only and MCP-assisted reviewers, seals assessments, and supplies blinded adjudication and explicit incomplete-result accounting. The enforced cross-family pilot records fresh Claude/Codex attempts, delivery failures and independent execution audits.

Impact measurements compare full and Git-selected validation, including missed consumer failures when dependency declarations are wrong. Fewer selected checks alone do not establish a safe or faster run.

Optional review-context and review-receipt exchange bounded selected source and external reviewer assessments. Source and review prose require --detailed --allow-review-source; claims and declared usage remain advisory. The engine does not call a model or upload code.