N8n:spec Driven Development

Spec-Driven Development

Specs live in .agents/specs/. They are the source of truth for architectural decisions, API contracts, and implementation scope. Implementation and specs must stay in sync — neither leads exclusively.

Core Loop

Read spec → Implement → Verify alignment → Update spec or code → Repeat

Before Starting Work

1. Find the spec. Search .agents/specs/ for files matching the feature:

ls .agents/specs/

2. Read the full spec. Understand scope, decisions, API contracts, and open questions before writing code.

3. If no spec exists and the task is non-trivial (new module, new API, architectural change), ask the user whether to create one first.

During Implementation

• Reference spec decisions — don’t re-decide what the spec already settled.
• When you diverge from the spec (better approach found, user requested change, constraint discovered), update the spec immediately in the same session. Don’t leave spec and code out of sync.
• Tick off TODO checkboxes (- [ ] → - [x]) as items are completed.
• Strike through or annotate items that were deliberately skipped or replaced, with a brief reason:

  markdownCopy

  - [x] ~~OpenRouter proxy~~ → Direct execution: nodes call OpenRouter directly

After Completing Work

Run a spec verification pass:

1. Re-read the spec alongside the implementation.
2. Check each section:
   • Do API endpoints in spec match the controller?
   • Do config/env vars in spec match the config class?
   • Does the module structure in spec match the actual file tree?
   • Do type definitions in spec match @n8n/api-types?
   • Are all TODO items correctly checked/unchecked?
3. Update the spec for any drift found. Common drift:
   • New files added that aren’t listed in the structure section
   • API response shapes changed during implementation
   • Config defaults adjusted
   • Architectural decisions refined
4. Flag unresolved gaps to the user — things the spec promises but implementation doesn’t deliver yet (acceptable for MVP, but should be noted).

Spec File Conventions

• One or more markdown files per feature in .agents/specs/.
• Keep specs concise. Use tables for mappings, code blocks for shapes.
• Use ## Implementation TODO with checkboxes to track progress.
• Split into multiple files when it helps (e.g. separate backend/frontend), but don’t enforce a rigid naming scheme.

When the User Asks to “Self-Review” or “Verify Against Spec”

1. Read all relevant specs.
2. Read all implementation files.
3. Produce a structured comparison:
   • Aligned: items where spec and code match
   • Drift: items where they diverge (fix immediately)
   • Gaps: spec items not yet implemented (note as future work)
4. Fix drift, update specs, report gaps to the user.