POSTFACT — Resolve Ambiguous Side Effects Before Retry
RemoteAbout POSTFACT — Resolve Ambiguous Side Effects Before Retry
POSTFACT resolves whether an ambiguous side-effecting action completed, helping autonomous software decide what to do before retrying. It reports DONE, NOT_DONE, or UNKNOWN from available evidence and does not execute the underlying action.
Key features
- 01Classifies outcomes as DONE, NOT_DONE, or UNKNOWN
- 02Reports retry safety, confidence, and evidence
- 03Accepts failure context and affirmative evidence
- 04Provides a next-step recommendation
Use cases
- 01Check whether an API action completed after a timeout
- 02Decide whether retrying a failed tool call is safe
- 03Hold for verification when evidence remains uncertain
MCP support
Exposes the `resolve_outcome` tool through a remote MCP endpoint. Its tool description directs agents to call POSTFACT after an ambiguous side-effect failure and before retrying.
Configuration
Remote servers need no local install. Pick your client, then copy the config or install in one click.
https://postfact-api-production.up.railway.app/mcpclaude mcp add --transport http gsterlingpress-postfact https://postfact-api-production.up.railway.app/mcp{"mcpServers":{"gsterlingpress-postfact":{"type":"http","url":"https://postfact-api-production.up.railway.app/mcp"}}}Open in Cursor{"servers":{"gsterlingpress-postfact":{"type":"http","url":"https://postfact-api-production.up.railway.app/mcp"}}}Open in VS Code{"mcpServers":{"gsterlingpress-postfact":{"type":"http","url":"https://postfact-api-production.up.railway.app/mcp"}}}{"mcpServers":{"gsterlingpress-postfact":{"serverUrl":"https://postfact-api-production.up.railway.app/mcp"}}}Run commands in a terminal; paste JSON into the client’s MCP config and restart. Servers that need sign-in will prompt on first connect.
Tools
1| Parameter | Type | Required | Description |
|---|---|---|---|
| method | string | No | |
| status | integer | No | |
| failure | string | No | |
| evidence | object | No | |
| evidence.providerStatus | string | No | |
| evidence.resourceExists | boolean | No | |
| evidence.receiptVerified | boolean | No | |
| evidence.transactionStatus | string | No | |
| evidence.preExecutionRejection | boolean | No | |
| requestId | string | No | |
| sideEffect | boolean | No | |
| resourceRef | string | No | |
| idempotencyKey | string | No | |
| transactionRef | string | No |
Details
From the project READMEPOSTFACT
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:
DONEonly when affirmative evidence establishes completion.NOT_DONEonly when affirmative evidence establishes non-execution.UNKNOWNwhenever evidence is insufficient.UNKNOWNis 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.
Comments
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