n8n-workflow-designlisted

# n8n Workflow Design Signature skill. This body is the Rule block the solutions-architect's output contract checks; deep node patterns live in `references/node-patterns.md`, read on demand. User instructions always override this skill. All factual output follows the anti-hallucination skill: cite or mark UNKNOWN, never guess. ## Rule block (every workflow spec must cover) 1. Trigger inventory: every entry point (webhook, schedule, manual, event) named. 2. Idempotency: a re-delivered trigger must not double-act (dedupe key or upsert). 3. Retry and error branches: each external call has a retry policy and an error path. 4. Secrets handling: credentials via the platform's secret store, never inline. 5. Webhook security: signature or token verification on every inbound webhook. 6. Observability node: one node logs run outcome for diagnosis. 7. Cost-per-run estimate: state it, so the ROI review has a number. ## Standard spec output format Trigger(s) -> nodes (in order) -> external calls -> error paths -> observability -> cost-per-run. The solutions-architect fills this shape into `state/automation-<slug>.md`. ## Two predecessor-earned rules - Model-authored notification text is sent plain, never through a Markdown or HTML parse mode. Arbitrary model text containing `_` or `*` silently kills a parsed send and drops the message entirely (observed live on a completion alert). - Scope note: n8n is for client and deliverable workflows, never a hop inside sefi-agents' own co