Postfact Api MCP Server

POSTFACT

Did the call actually happen?

POSTFACT is a tiny ambiguous-outcome resolver for autonomous software. Use it after a side-effecting API/tool action fails ambiguously and before retrying.

Production: https://postfact-api-production.up.railway.app

It is intentionally strict:

• DONE only when affirmative evidence establishes completion.
• NOT_DONE only when affirmative evidence establishes non-execution.
• UNKNOWN whenever evidence is insufficient. UNKNOWN is the safe default.

POSTFACT does not execute the underlying action, move money, or pretend a timeout means failure.

REST

Production endpoint: POST https://postfact-api-production.up.railway.app/v1/resolve

Input accepts method/status/failure, side-effect and idempotency context, durable references, and optional affirmative evidence. Output is state, retry_safe, confidence, evidence, and next.

MCP

Remote endpoint: POST https://postfact-api-production.up.railway.app/mcp

Tool: resolve_outcome

The tool description explicitly tells agents to invoke POSTFACT after an ambiguous side-effect failure and before retry.

Middleware-shaped contract

const outcome = await postfact.resolve(failureContext)
if (outcome.state === 'DONE') return completed
if (outcome.state === 'NOT_DONE' && outcome.retry_safe) return retry()
return verifyOrHold()

Future SDKs can wrap retry middleware without changing the wire contract.

POSTFACT + RECOVER

POSTFACT answers what can we establish happened? RECOVER answers what is the safest next action? A future retry stack can call POSTFACT first, then RECOVER when the outcome remains uncertain.

Safe discovery and demo

• Health: GET https://postfact-api-production.up.railway.app/health
• Demo: GET https://postfact-api-production.up.railway.app/demo
• Activity: GET https://postfact-api-production.up.railway.app/activity
• Machine-readable activity: GET https://postfact-api-production.up.railway.app/activity.json

GET /demo is deliberately excluded from real-use analytics.

Real-use scoreboard

GET /activity shows the permanent FIRST 10 TRUE STRANGERS scoreboard. GET /activity.json exposes its machine-readable summary. Demo/internal traffic is excluded. Production persistent storage is mounted at /data.

Run

npm test
npm start

Default port: 8080.