design-docs - SKILL.md Agent Skill

name: design-docs description: > Full execution protocol for MODE: DESIGN_DOCS — generate or sync structured, language-agnostic design docs (domain.md, technical-spec.md, behavior-spec.md, reference/) for the project under build, with a stable section-ID registry and a design changelog. Loaded on demand by the architect when the design-docs command emits a [MODE: DESIGN_DOCS ...] signal (issue #1080).

Design-Doc Generation & Sync Protocol

Generate or maintain the project's structured design documentation. The work is delegated to the docs_design agent (a design-doc-author role variant of the docs agent). This mode authors a fixed set of version-controlled docs in the target project repo (NOT under .swarm/). It does NOT modify source code, does NOT call declare_scope, and does NOT touch .swarm/spec.md, CHANGELOG.md, or docs/releases/pending/*.

MODE: DESIGN_DOCS

Step 0 — Parse Header

Parse the [MODE: DESIGN_DOCS ...] header to extract:

out: output directory, project-relative (default docs)
lang: target language for reference/ docs, or auto (default auto)
update: boolean — true = sync existing docs to current code/spec; false = generate fresh
the trailing free text = the system description (required when update=false)

If the header is malformed, report the error and stop.

Step 1 — Preconditions

Confirm design_docs.enabled is true (the docs_design agent only exists when enabled). If it is not, tell the user to set design_docs.enabled: true in opencode-swarm.json and stop.
If a spec-staleness block is active (.swarm/spec-staleness.json present), resolve/acknowledge spec staleness FIRST — otherwise design-doc writes may be blocked by the guardrail. Do not blindly retry on SPEC_STALENESS_BLOCK.
Read .swarm/spec.md if present — it is the authoritative requirements source (FR-### IDs). The design docs must be consistent with it.

Step 2 — Index Existing State (always)

Have the docs_design agent (or doc_scan) index <out>/ to discover any existing design docs. If <out>/reference/traceability.json exists, it is the section-ID registry — load it. Existing section IDs MUST be preserved on regeneration.

Step 3 — Generate or Sync

Dispatch the docs_design agent (the active swarm's docs_design — never the standard docs agent) with:

TASK, MODE (generate|sync), OUT_DIR, LANGUAGE
For sync: FILES CHANGED and CHANGES SUMMARY from the current phase/diff
SKILLS: file:.opencode/skills/design-docs/SKILL.md (this skill)

The agent owns exactly these files under <out> and creates NOTHING else:

<out>/
├── domain.md              # 100% language-agnostic. Entities in neutral notation
│                          #   (field: type-class), domain invariants. ZERO framework
│                          #   names in normative text. Section IDs: D-###
├── technical-spec.md      # Language-agnostic architecture: layers, dependency rules,
│                          #   contract SHAPES (inputs→outputs→error-kinds), algorithms,
│                          #   invariants. + the traceability table. Section IDs: S-###
├── behavior-spec.md       # 100% language-agnostic Given/When/Then specs. IDs: B-###
├── design-changelog.md    # Keep-a-Changelog log of design-doc changes (NOT release notes)
└── reference/             # ALL [INCIDENTAL] language/framework-specific material here.
    ├── reference-impl.md  #   Exact signatures, CLI strings, SQL, code. Mapped to
    │                      #   spec sections by ID. Section IDs: R-###
    ├── idiom-notes.md     #   "Here is how the reference solved X" — examples only.
    └── traceability.json  #   Machine-readable section-ID registry (source of truth)

Step 4 — Invariants the docs MUST satisfy

Language-agnostic normative text: domain.md, technical-spec.md, and behavior-spec.md contain ZERO framework/library/language names in normative content. All such material lives ONLY in reference/.
Version header on every doc: 
Stable section IDs: assigned once, never renumbered. D-### domain, S-### technical-spec, B-### behavior-spec, R-### reference. On sync, reuse every existing ID; mint new IDs only for genuinely new sections.
Traceability footer ending each section: > Traceability: FR-012, FR-013 | invariant: <id-or-none>.
traceability.json kept in sync: { "schema_version": 1, "sections": [ { "section_id", "doc", "title", "spec_frs": [], "invariants": [], "code_anchors": [] } ] }. technical-spec.md renders a human-readable mirror table | Doc Section | Spec FR | Invariant | Code anchors |.
design-changelog.md: append one entry per generate/sync under ## [Unreleased] (Added/Changed/Removed), e.g. - <ISO date> phase <N>: <sections touched> (<FR refs>). This file is SEPARATE from release-please artifacts — never edit CHANGELOG.md or docs/releases/pending/* here.

Step 5 — Verify & Report

Confirm the agent created/updated only the allowed files and traceability.json is consistent with the docs.
Confirm no normative doc names a framework (spot-check) and every section has an ID + traceability footer.
Report UPDATED / ADDED / REMOVED / SUMMARY back to the user.

Notes on the PHASE-WRAP sync path

During PHASE-WRAP, the deterministic design-doc drift check (runDesignDocDriftCheck) writes .swarm/doc-drift-phase-N.json. If the verdict is DOC_STALE and design_docs.enabled, dispatch docs_design in sync mode for the affected sections only, then append a design-changelog entry. This is advisory and non-blocking — never block phase completion on design-doc lag.