# Signalint

> A local stdio MCP server for compact, prioritized JavaScript and TypeScript diagnostics.

Documentation for Signalint 1.2.1, check-response schema 1.4. Requires Node.js >= 22.12.0.

Signalint orchestrates Oxlint, TypeScript, Biome, and project-local flat ESLint. Since 1.1.0, Oxlint and TypeScript are optional peers, not guaranteed bundled engines. Diagnostic checks do not edit source; explicit apply_diagnostic_fix can write caller-provided full-file replacements. Writes are sequential with best-effort rollback, not filesystem-atomic; post-check failure does not revert them and apply does not revalidate previewed paths. Cache/session artifacts default under .signalint/ with supported state overrides. Clustering is a rule-and-scope heuristic, not proven semantic root-cause analysis. Priority 1 is most urgent, 5 least urgent.

The signalint-mcp binary starts the MCP server and now dispatches recognized CLI verbs. The explicit signalint CLI supports check, doctor, stats --json, and check --compact. Default both-mode get_issue_detail returns an array in text content and { issues: [...] } in structuredContent. Text mode omits structured content/output schemas; structured mode uses a short text summary. Checks return up to 10 multi-issue clusters and 100 flat remaining records. get_live_diagnostics can enumerate latest internal/buffered issue IDs, but is not historical snapshot pagination. check_files filters displayed diagnostics to requested paths; TypeScript remains whole-program and adds a bounded source-metadata fingerprint. There are 13 tools, retained snapshots/delta, hook adapters and opt-in pnpm workspace planning. Supplied LSP and Python/Rust/Go report normalizers do not launch new native engines; empty ingestion does not clear old buffer entries. Hooks can approve clustered errors or all-disabled checks. Delta advice is not coverage proof. Read the limitations before relying on cached results, hooks, transactions or CLI thresholds.

- [Complete plain-text documentation](https://tranqui004.github.io/signalint-site/llms-full.txt): All pages in one file.
- [Source repository](https://github.com/TranQui004/signalint): Runtime implementation and tests.

## Get started

- [Meet Signalint](https://tranqui004.github.io/signalint-site/docs/): A local MCP server that turns JavaScript and TypeScript diagnostics into feedback your coding agent can use.
- [Installation](https://tranqui004.github.io/signalint-site/docs/getting-started/installation/): Install Signalint in your repository, detect your engines, and verify the setup.
- [Quickstart](https://tranqui004.github.io/signalint-site/docs/getting-started/quickstart/): Connect your agent, inspect a project, retrieve issue details, and verify an edit.

## Connect your client

- [Connect your client](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/): Review the seven clients named in the setup registry and verify the active configuration and project root.
- [Claude Code](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/claude-code/): Registry-based setup for Claude Code; confirm the active client configuration and project root.
- [Cursor](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/cursor/): Registry-based setup for Cursor; confirm the active client configuration and project root.
- [Codex CLI](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/codex-cli/): Registry-based setup for Codex CLI; confirm the active client configuration and project root.
- [Antigravity](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/antigravity/): Registry-based setup for Antigravity; confirm the active client configuration and project root.
- [VS Code](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/vscode/): Registry-based setup for VS Code; confirm the active client configuration and project root.
- [Windsurf](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/windsurf/): Registry-based setup for Windsurf; confirm the active client configuration and project root.
- [Zed](https://tranqui004.github.io/signalint-site/docs/getting-started/clients/zed/): Connect Signalint through Zed's context_servers configuration and verify the workspace root.
- [Multiple projects](https://tranqui004.github.io/signalint-site/docs/getting-started/multiple-projects/): Avoid stale global paths and keep each agent connected to the intended repository.

## Guides

- [Configuration](https://tranqui004.github.io/signalint-site/docs/guides/configuration/): Choose engines, MCP payload mode, ignore paths, and subprocess deadlines.
- [Diagnostic engines](https://tranqui004.github.io/signalint-site/docs/guides/engines/): Engine resolution, TypeScript configuration selection, and the limits of diagnostic checks.
- [CLI reference](https://tranqui004.github.io/signalint-site/docs/guides/cli/): Current entrypoint dispatch, compact checks, JSON session stats, and CI threshold caveats.
- [Troubleshooting](https://tranqui004.github.io/signalint-site/docs/guides/troubleshooting/): Resolve startup problems, wrong-project checks, engine failures, and stale cached results.
- [Snapshots & edit verification](https://tranqui004.github.io/signalint-site/docs/guides/snapshots-and-delta/): Pin diagnostic details to a retained check, compare two snapshots, and verify a scoped edit without confusing delta with coverage.
- [Verify-after-edit hooks](https://tranqui004.github.io/signalint-site/docs/guides/hooks/): Preview and install the emitted hook configurations, understand post-edit versus stop checks, and review the 1.2.1 policy limitations.
- [Monorepos & incremental TypeScript](https://tranqui004.github.io/signalint-site/docs/guides/monorepos/): Opt into YAML-based pnpm workspace discovery, include/exclusion globs, dependency/reference ordering and partitioned TypeScript state.
- [Live & external diagnostics](https://tranqui004.github.io/signalint-site/docs/guides/live-diagnostics/): Supply LSP-shaped diagnostics, query the live buffer, and understand how Python, Rust and Go report normalizers differ from native engine execution.
- [Preview & apply transactions](https://tranqui004.github.io/signalint-site/docs/guides/fix-transactions/): Stage full-file replacements, review apply-time path/hash checks, pin an optional baseline, and understand journal, rollback and verification limits.

## Reference

- [MCP tools](https://tranqui004.github.io/signalint-site/docs/guides/tools/): Accepted arguments, response shapes, side effects and error handling for all 13 tools in Signalint 1.2.1.
- [Response schema](https://tranqui004.github.io/signalint-site/docs/reference/response-schema/): Schema 1.4 clusters, flat remaining issues, compact keys, and reference identity limits.
- [Clustering & priorities](https://tranqui004.github.io/signalint-site/docs/reference/priority-ladder/): Rule groups, flat overflow records, and the deterministic priority 1–5 ladder.
- [Caching](https://tranqui004.github.io/signalint-site/docs/reference/caching/): Content keys, TypeScript metadata fingerprints, SQLite contention waits, and unresolved cache limits.
- [Loop & churn detection](https://tranqui004.github.io/signalint-site/docs/reference/loop-detection/): Two independent signals for recurring diagnostics and repeated file-rule checks.
- [Architecture](https://tranqui004.github.io/signalint-site/docs/reference/architecture/): The local diagnostic pipeline, its stateful layers, and the boundaries between them.
- [Known limitations](https://tranqui004.github.io/signalint-site/docs/reference/limitations/): Source-verified boundaries of Signalint 1.2.1, including hook coverage, snapshot identity, live-buffer semantics and source-writing transactions.
- [Benchmarks & payload costs](https://tranqui004.github.io/signalint-site/docs/reference/benchmark/): Audited 1.2.1 fixture bytes, three transport modes, and the limits of the measurements.
- [FAQ](https://tranqui004.github.io/signalint-site/docs/reference/faq/): Practical answers about engines, payload modes, caching, diagnostics, and setup boundaries.
- [MCP payload modes](https://tranqui004.github.io/signalint-site/docs/reference/payload-modes/): Understand the 1.2.1 JSON text fallback, optional structured-mode summary, measured duplication and compact-key limits.

## Project

- [Changelog](https://tranqui004.github.io/signalint-site/docs/about/changelog/): Source-verified 1.2.1 hardening for snapshot detail, MCP serialization/errors, workspace discovery and journaled apply, with historical release context.
- [Contributing](https://tranqui004.github.io/signalint-site/docs/about/contributing/): Set up the source project, verify a change, or improve the documentation site.
- [Security](https://tranqui004.github.io/signalint-site/docs/about/security/): Understand native-check containment, explicit source-writing permissions, local state, transaction race limits and private vulnerability reporting.