Webhook an agent run with a fixed skill prompt
An n8n workflow accepts a signed webhook, loads your pinned SKILL.md prompt, and starts an agent run with the same guardrails every time.
A callable URL that enqueues one agent job with your skill text, logs the payload, and stops before silent auto-merge or send.
- 1
Pin the skill text
Fetch SKILL.md from a tagged commit or paste a hash in the workflow notes. Floating main defeats the point of a fixed prompt.
- 2
Fire ten test webhooks
Include one bad secret and one missing field. Confirm errors never still call the agent.
- 3
Read the logs before wiring send
Review ten real outputs manually. Only then add Slack or PR automation on a separate branch with approval.
The prompt to paste
Design an n8n workflow that kicks off an agent run using a fixed skill prompt from our repo. Inputs I will provide: - Sample webhook JSON: [paste fields such as ticket id, repo, branch, requester] - The SKILL.md text or a URL to raw SKILL.md in git (paste excerpt if short) - Target agent API: [name: e.g. internal runner, Claude API, Cursor background agent — or write "HTTP step only"] Requirements: 1. Webhook POST with shared-secret header [header name]; reject bad auth to an error branch that logs reason only. 2. Validate required fields [list them]. Missing fields → structured error response, no agent call. 3. Build the agent prompt by concatenating: skill text, a delimiter, and the webhook payload as JSON. 4. Call the agent via HTTP Request node (show URL placeholder and method). Include timeout and retry policy in comments, not infinite retry. 5. Persist run id, timestamp, and requester to a log sink I name: [Sheet, database, or n8n execution data — pick one]. 6. Human gate: workflow must stop after logging the agent response. No automatic PR merge, email, or Slack unless I add a separate approval branch later. Deliver: - Node list in order with node types - Expression for the secret check - The prompt assembly formula - Example success and error JSON responses from the webhook Do not store API keys in the workflow JSON. Reference n8n credentials by name.
A webhook that runs a skill is still an open door. Rotate the secret when people leave and rate-limit at the edge if the URL leaks.
Sample case written by Hidden Logic Lab. Not affiliated with n8n.
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