Spec Driven Development
by formulahendry
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Runs on your computer★ 440MITUpdated 14 months ago
Install
POSTFACT — Resolve Ambiguous Side Effects Before Retry
Overview
Description from the maker (original English)
Resolve whether an uncertain side-effecting action completed before software retries it.
PopNx MCP’s three pillars
These three are never merged into one score: opinions, measurements and popularity are different things.
- User voiceiNo reviews yetReviews open together with accounts in a later step
- Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
- UsageiNot measured yet★ –
What you can do with it
We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.
- Connection: Runs in the cloud
- Transport: Streamable HTTP
- Category: Other
Install
Pick the AI app you use, then copy the settings.
Before you install
- Basic checks: 1 of 1 passed
- Runs on the maker’s server: what you ask it goes through their server.
- The registry lists no key to fill in.
You need
- Runs in the cloudNothing to install; it connects over the internet
Which app do you use?
Pick your app above. We remember it, so next time the button says “Install in …”.
Works in Claude on the web, desktop and mobile:
- Open Settings → Connectors
- Press Add custom connector
- Paste the address below and press Add
- If it asks you to sign in, sign in with the maker
https://postfact-api-production.up.railway.app/mcpRun this in your terminal
claude mcp add --transport http postfact https://postfact-api-production.up.railway.app/mcpOr copy the settings yourself
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"postfact": {
"url": "https://postfact-api-production.up.railway.app/mcp"
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
Or copy the settings yourself
Paste into .vscode/mcp.json in your project
{
"servers": {
"postfact": {
"type": "http",
"url": "https://postfact-api-production.up.railway.app/mcp"
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
ChatGPT connects only to servers on the internet:
- Open ChatGPT on the web → Settings → Connectors (Apps)
- Press Create or Add (some plans need Developer mode under Advanced first)
- Paste the address below, give it a name and save
- If it asks you to sign in, sign in with the maker
https://postfact-api-production.up.railway.app/mcpMenu names can differ slightly by plan and over time.
Your choice stays on this device in a cookie; no account needed.
These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.
What it can do
We have not read this server’s tool list yet; we check endpoints in rotation.
Basic checksi
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026
- ✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account GSterlingPress, which owns the repo
- … Not checked yet
Still maintained
We have not read this repo from GitHub yet
- … Not checked yet
Has a licence
We have not read this repo from GitHub yet
- … Not checked yet
Endpoint responds
Not checked yet; we check endpoints in rotation
- … Not checked yet
Sign-in with OAuth
Not checked yet; we check endpoints in rotation
- … Not checked yet
No hidden instructions in tool descriptions
Not checked yet; we read the tool list when we check the endpoint
Compared with others in Otheri
- More stars than 0% of the other 32568 servers in this category
- Published to the registry more recently than 42% of the other 32568 servers in this category
- Basic checks equal to or better than 100% of the other 32568 servers in this category
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
Common questions
Is POSTFACT — Resolve Ambiguous Side Effects Before Retry safe?
It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
What keys or codes does it need?
The registry does not list a required key, though some servers ask you to sign in on first use.
Does it run on my computer or in the cloud?
It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.
Is it still maintained?
The GitHub repo last changed –, and the latest version (0.1.1) reached the registry 2 months ago.
Which apps can use it?
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.
What can I use instead?
In the same category: Spec Driven Development, Remote Desktop Commander, FlyDocs
Alternatives
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Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
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Runs in the cloud★ 211Updated yesterday
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FlyDocs
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Runs on your computerUpdated today
Install
README from the maker
Open the README
Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.
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:
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 testnpm start
Default port: 8080.