Local stdio MCP / signalint-mcp@0.2.0
Signalint is a local stdio MCP server that runs Oxlint, TypeScript, and optional Biome checks—then caches unchanged work, clusters repeated issues, and flags fix loops before sending a versioned response back to the coding agent.
npm install --save-dev signalint-mcp && npx signalint-mcp initCurrent 40-issue fixture: 9,151 B raw versus 1,233 B clustered.
Latest local acceptance run; the enforced ceiling is 300 ms for the 50-file fixture.
Forty raw issues grouped into four rule-first clusters.
Maximum project-relative paths accepted in one MCP call.
01 / response
Scroll through the recorded 40-issue fixture as normalized rows become a bounded schema 1.1 response.
The engines stay authoritative. Signalint first normalizes their locations, rule IDs, severity, and messages.
Large rule groups spanning multiple files receive one root-cause summary and distinct sample issue IDs.
The controlled fixture falls from 9,151 bytes to 1,233 bytes while preserving engine state and issue references.
02 / mechanics
Signalint preserves the diagnostic engines as the source of truth and makes cache, failure, and loop state explicit.
check_filesZod schemas reject malformed arguments. Canonical path checks keep every accepted file inside the project root.
3 paths acceptedFile-local engines receive misses. TypeScript runs against the complete configured program when relevant files change.
Engine-native diagnostics become normalized issues before rule-first grouping assigns priority and distinct issue references.
40 issues → 4 clustersSchema 1.1 keeps each engine's outcome explicit, so one failure cannot erase another engine's diagnostics.
schemaVersion 1.1A result is reused only when file content, the recognized root engine-config hash, Signalint code version, and the installed engine version still match.
sha256(file content)
: engine
: engine config hash
: signalint version
: engine versionAn issue that disappears and returns repeatedly produces a narrow warning, not a guess about the wider conversation.
{
"signature": "no-unused-vars:<identifier> is unused",
"occurrences": 3,
"hint": "This issue was fixed and reappeared 3 times — consider a different approach"
}One engine can fail without discarding diagnostics another engine already completed.
"engines": {
"oxlint": { "status": "ok" },
"tsc": { "status": "error", "message": "..." },
"biome": { "status": "disabled" }
}Default deadlines are 30 seconds for Oxlint, 120 seconds for tsc, and 30 seconds for Biome. Timeout and cancellation terminate the process tree.
The SQLite cache evicts least-recently-used rows above 10,000 entries. Session history replays a bounded tail and rotates to a single .1 backup.
03 / engines
Signalint coordinates three tools without pretending they work alike. Cache decisions follow each engine's real scope.
File-local analysis
Signalint batches misses and stores normalized results per engine and file.
Whole-program analysis
Normal roots use --project; solution-style roots with references use --build.
Optional file-local analysis
Disabled by default, with an explicit engine status in every check response.
04 / clients
One local server, three client-specific configuration paths. The init command detects nearby clients and writes only after confirmation.
Share a project-local MCP entry through .mcp.json.
claude mcp add --scope project signalint …Use .cursor/mcp.json with the published npm binary.
npx --no-install signalint-mcpSet an explicit project working directory in mcp_config.json.
cmd /c npx --no-install signalint-mcp