phx-document

name	phx:document
description	Generate @moduledoc and @doc strings for Elixir modules, contexts, and schemas. Use when explicitly asked to write @doc/@moduledoc — NOT for README or external docs.
effort	low
argument-hint	["plan-file OR feature-name"]

Document

Generate documentation for newly implemented features.

Usage

/phx:document .claude/plans/magic-link-auth/plan.md
/phx:document magic link authentication
/phx:document  # Auto-detect from recent plan

Iron Laws

1. Never remove existing documentation — Existing docs may reflect design intent that isn't obvious from code alone; update rather than replace
2. @moduledoc on every public module — Undocumented modules accumulate quickly and create onboarding friction for new team members
3. ADRs capture the "why", not the "what" — Code shows what was built; ADRs explain why this approach was chosen over alternatives
4. Match @doc to function's public API — Document parameters, return values, and edge cases; callers shouldn't need to read the implementation
5. DO NOT add @doc to untested code — documentation implies a stable contract; document only after tests confirm the function behaves as described

What Gets Documented

Output	Description
@moduledoc	For new modules missing documentation
@doc	For public functions without docs
README section	For user-facing features
ADR	For significant architectural decisions

Workflow

Step 0: Pre-check (avoid no-op runs)

Run git diff --name-only HEAD~5 | grep '\.ex$' | head -20 to check for new .ex files.

If NO new .ex files were added (only modifications), skip the full audit and report: "No new modules — documentation coverage unchanged." This prevents 35-message analysis sessions that conclude "PASS" with zero output (confirmed: session bb0a0454 wasted ~2K tokens on no-op).

1. Identify new modules from recent commits or plan file
2. Check documentation coverage (@moduledoc, @doc)
3. Generate missing docs using templates
4. Add README section if user-facing feature
5. Create ADR if architectural decision was made
6. Write report to .claude/plans/{slug}/reviews/{feature}-docs.md

When to Generate ADRs

Trigger	Create ADR
New external dependency	Yes
New database table	Maybe (if schema non-obvious)
New OTP process	Yes (explain why process needed)
New context	Maybe (if boundaries non-obvious)
New auth mechanism	Yes
Performance optimization	Yes

Integration with Workflow

/phx:plan → /phx:work → /phx:review
       ↓
/phx:document  ← YOU ARE HERE (optional, suggested after review passes)

References

• ${CLAUDE_SKILL_DIR}/references/doc-templates.md — @moduledoc, @doc, README, ADR templates
• ${CLAUDE_SKILL_DIR}/references/output-format.md — Documentation report format
• ${CLAUDE_SKILL_DIR}/references/doc-best-practices.md — Elixir documentation best practices
• ${CLAUDE_SKILL_DIR}/references/documentation-patterns.md — Detailed documentation patterns