Design Harvest

The on-ramp. Three modes.

Mode 1: harvest (/mddesign:harvest)

Goal: produce a structurally valid DESIGN.md at project root from the existing codebase.

Step 1: Pre-flight

• Glob for DESIGN.md at project root.
• If it exists and the user did NOT pass --overwrite, refuse: print "DESIGN.md already exists. Use /mddesign:critique instead, or pass --overwrite to replace."
• Confirm npx is available (bash -c "command -v npx").

Step 2: Dispatch the design-archeologist subagent

Call the Agent tool with subagent_type: design-archeologist and a prompt containing this PhaseSpec:

phase_id: harvest-<short-uuid>
parent_plan_ref: ./task_plan.md
goal: Extract de-facto design tokens from this codebase and return a draft DESIGN.md body following the Google Labs spec.
done_when:
  - draft_design_md is non-empty
  - draft_design_md contains YAML frontmatter and 8 ordered markdown sections
  - draft_design_md includes a section #9 "Agent Prompt Guide"
inputs:
  files: []  # the subagent globs the project itself
tools_allowed: ["Read", "Glob", "Grep", "Bash"]
tools_denied: ["Write", "Edit", "WebFetch"]
budget:
  max_tool_calls: 200
  max_wall_seconds: 600
hitl_checkpoints:
  - before_returning_draft
return_contract:
  format: markdown+frontmatter
  fields: [summary, draft_design_md, open_questions]

The subagent has its own dedicated SKILL/agent definition at agents/design-archeologist.md.

Step 3: Receive the draft, write to DESIGN.md

• Take the draft_design_md field from the subagent's return.
• Write it to <project_root>/DESIGN.md. This write goes through the PreToolUse HITL gate (named checkpoint: before_design_md_write).

Step 4: Lint and iterate

Run:

npx --yes @google/design.md lint DESIGN.md

If exit code is 0, you are done.

If non-zero, capture the linter output. Re-dispatch design-archeologist with an additional input field lint_errors: <output> and instruction "fix every reported error and return a new draft." Loop up to 3 times. After 3 failed iterations, surface the final lint errors to the user and stop.

Step 5: Append to progress.md

Append under ### Phase harvest-<short-uuid> Result:

• Final lint status
• File path of DESIGN.md
• Token counts (colors: N, typography levels: N, spacing levels: N, components: N)
• One-line "next step" pointing the user to /mddesign:critique.

Mode 2: critique (/mddesign:critique)

Goal: write DESIGN.md.critique.md adjacent to DESIGN.md with five audit passes.

Step 1: Pre-flight

• Confirm DESIGN.md exists. If not, refuse with "No DESIGN.md found. Run /mddesign:harvest first."

Step 2: Pass 1 — Structural (delegated)

npx --yes @google/design.md lint DESIGN.md --json

Capture findings. Severity comes from the linter.

Step 3: Pass 2 — Drift

• Read DESIGN.md and parse the YAML frontmatter token table.
• Glob the project for UI files (**/*.{tsx,jsx,vue,svelte,html,css,scss} plus tailwind.config.*).
• For each declared token (color, font, radius, spacing), grep the project for actual usage.
• Findings:
  • Orphan: declared token never used in code.
  • Leak: a hex color, font name, or radius value used in code that does not resolve to any declared token.
  • Near-duplicate: two declared colors within ΔE < 5 (or two radii within 1px of each other).

Step 4: Pass 3 — Accessibility

• For every declared color pair where one is a *background* and one is a *text* token, compute WCAG AA contrast. Flag below 4.5:1 (normal text) or 3:1 (large text).
• Check whether colors.focus-ring exists. If not, finding: "Missing focus-ring token; users tabbing through cannot see focus."
• Check whether any motion or animation tokens are declared. If yes, check whether a prefers-reduced-motion fallback section is present in DESIGN.md. If not, finding.

Step 5: Pass 4 — Completeness

• For each component declared, check whether hover, active, focus, disabled, and error variants are defined. Flag missing variants.
• Check whether dark-mode color counterparts exist (a parallel colors-dark.* block or @media (prefers-color-scheme: dark) overrides).
• Check whether responsive breakpoints are declared.

Step 6: Pass 5 — Consistency

• Check spacing scale: are values geometrically progressing (e.g., 4, 8, 16, 32) or are there orphan values (e.g., 4, 8, 11, 32)?
• Check radius scale: same.
• Check font-size scale: same.

Step 7: Write the critique

Write DESIGN.md.critique.md at project root, adjacent to DESIGN.md. Format:

# DESIGN.md Critique

> Generated by MDDesign on <ISO timestamp>. Five audit passes.

## Summary
<N findings: P0 P1 P2 P3 counts>

## Findings

### F1 [P0 / structural / google-lint] Missing primary color
DESIGN.md has no `colors.primary` token. Required by Google linter rule 2.
Fix: declare `colors.primary` in the YAML frontmatter.
`/mddesign:fix F1`

### F2 [P1 / drift / leak] Hex color #FF6B6B used 14 times in code, not declared
Locations: src/components/Alert.tsx:23, src/components/Toast.tsx:11, ...
Fix: add `colors.danger = #FF6B6B` to DESIGN.md and replace literal usage.
`/mddesign:fix F2`

<...>

Each finding has a stable F<N> id, a severity (P0 P1 P2 P3), a category, a one-line description, evidence, a proposed fix, and the /mddesign:fix <id> slash command.

Step 8: Append to progress.md

Append a one-line summary and a pointer to the critique file.

Mode 3: fix (/mddesign:fix <finding-id>)

Goal: apply ONE finding's fix from the critique.

Step 1: Read the critique

• Open DESIGN.md.critique.md, find the finding by id.
• If not found, refuse.
• If status is already applied, refuse.

Step 2: Show the proposed change

• Print the finding to the user.
• The PreToolUse hook will intercept the next Write or Edit (named checkpoint: before_design_md_fix) and require approval.

Step 3: Apply

• Make the single edit on DESIGN.md (or, when the fix touches code, the named source file).
• After every edit, re-run npx --yes @google/design.md lint DESIGN.md. If lint regresses, revert the edit and surface the error.

Step 4: Update the critique

• Mark the finding status: applied in DESIGN.md.critique.md.
• Append to progress.md: "Applied F<id>. DESIGN.md still passes lint."

Core rules

• Never write to DESIGN.md outside /mddesign:harvest and /mddesign:fix.
• Always write DESIGN.md at project root, not anywhere else.
• Never reimplement what npx @google/design.md lint does.
• Always honour the HITL gate.
• Never edit task_plan.md. Append to progress.md only.

External dependency

@google/design.md (npm, Apache 2.0). Use npx --yes @google/design.md .... No global install required at consume time.