tdd-author

TDD authoring

Run once after a PRD update. YOU decide how many TDDs to write, and their scope, based on what changed. Persist each to docs/tdd/NNNN-<slug>.md.

Relationship to superpowers (read first)

This skill IS the technical-design step for throughline — the governance-producing equivalent of superpowers:writing-plans. When the user invokes /tdd-author, do NOT also invoke superpowers:brainstorming or writing-plans; this skill owns the phase and its output is the TDD/ADR design-of-record (see [[ADR 0001]] in docs/adr/). If a docs/superpowers/plans/* (or specs/*) file or other prior design notes exist, READ and fold in their substance rather than redoing the work; they are transient input, never authoritative, never relocated. The canonical record is docs/tdd/ + docs/adr/. A throughline TDD is a DESIGN, not a step-by-step build script — the bite-sized failing-test-first task breakdown is /build-tdds's job, so do not reproduce it here.

0. Resume check

Resolve the plugin tree from the first set of CLAUDE_PLUGIN_ROOT / GROK_PLUGIN_ROOT (env names; fail closed via tl_plugin_root), then source the draft helper: _tl_src="${CLAUDE_PLUGIN_ROOT:-${GROK_PLUGIN_ROOT:-}}"; . "${_tl_src}/scripts/lib/plugin-root.sh" then source "$(tl_plugin_root)/scripts/lib/drafts.sh". If sourcing fails (non-zero exit — the helper file is missing or broken), warn the user that draft persistence is unavailable and proceed in degraded mode WITHOUT it (the design pass still works; FR-46's recovery guarantees do not apply this run). Do not invoke any tl_draft_* function in degraded mode. Otherwise resolve the draft path once: dpath="$(tl_draft_path tdd-author)".

• If that command exits non-zero — neither CLAUDE_PLUGIN_DATA nor GROK_PLUGIN_DATA is set and writable, and tl_drafts_dir has printed a diagnostic to stderr — enter the same degraded mode: warn the user and proceed without persistence.
• Otherwise pick exactly one of three mutually exclusive cases:
  1. tl_draft_exists tdd-author is true → a parseable draft is present. Run tl_draft_summary tdd-author and present its output to the user via a structured multiple-choice question with options Resume from draft / Discard and start fresh. PRD-drift check: compare git log -1 --format=%h -- docs/PRD.md (the short SHA of the PRD's last-touching commit — NOT git rev-parse --short HEAD docs/PRD.md, which parses the path as a revision and exits 128) to the draft's prd_rev_at_start; if they differ, add this line to the resume prompt: PRD has advanced since this draft was started (<old> → <new>). Your interview answers may no longer apply. — the user decides resume vs. discard with the drift surfaced. On resume, run tl_draft_read tdd-author and use its interview and draft_doc as your starting state (do NOT re-elicit anything already in interview); the draft already exists, so do NOT call tl_draft_init. If the user resumes DESPITE drift, re-run step 1's PRD-delta logic from the NEW PRD SHA and re-present the step-3 PLAN before authoring — the drift may change the TDD set. On discard, tl_draft_discard tdd-author.
  2. tl_draft_exists tdd-author is false BUT [ -f "$dpath" ] is true → a file is present but does not parse. Warn "found a draft at $dpath but it is not parseable — ignoring" and proceed as for no draft. Do NOT call tl_draft_init here; lazy init at step 5 overwrites the bad file atomically. (tl_draft_exists returns non-zero for BOTH "no file" AND "file present but unparseable", so the explicit [ -f "$dpath" ] test is what disambiguates them — without it this warning path is unreachable and a corrupt draft would be silently treated as "no draft".)
  3. Neither → no draft. Simply proceed; do NOT call tl_draft_init here.