fix(pdca): complete predecessor phase Task before advancing (#137, v2.1.29)

[agent-kay-it]

Summary

Fixes #137 (@hslee-cmyk, low-priority/cosmetic, reported with a full reproduction).

The pdca skill chains phase Tasks via blockedBy ([Plan]→[Design]→[Do]→[Check]→…), but skills/pdca/SKILL.md documented Task creation only — no step ever told the model to mark the predecessor phase Task completed when advancing, and no hook did it either. A predecessor left in_progress (e.g. [Design] for the entire Do phase) leaked a stale phase into Claude Code's ambient prompt context every turn, disagreeing with .bkit/state/pdca-status.json's phase field — the phase source of truth, which was correct throughout.

Root cause & why Option 2 was rejected (infeasible)

The issue offered two fixes. Option 2 (a hook auto-completing the predecessor) is technically infeasible: per the official Claude Code hooks guide, command hooks communicate via stdout/stderr/exit-code/additionalContext only and cannot call TaskUpdate — only the model can. TaskCreated/TaskCompleted are real firing events, but a handler could at most emit a reminder that still relies on the model acting — no more deterministic than an explicit skill step, and noisier. Option 1 is therefore strictly better. (Verified against CC docs — not assumed.)

Fix (Option 1 — deterministic, model-executed)

• skills/pdca/SKILL.md: each advancing action (design/do/analyze/iterate/qa/report) embeds a "Complete predecessor Task first" step immediately before its Create-Task step; archive completes the terminal [Report] Task; plan completes an optional [PM] Task.
• New ### Phase Transition Rule (task completion) subsection under ## Task Integration states the general rule (complete every prior in_progress [Phase] {feature} Task) and the two-sources-of-truth rationale. Branch-safe for the qa/act parts of the 9-phase lifecycle.
• Uses the TaskList/TaskUpdate tools the skill already grants — no hook change, no new runtime surface, no dead code.

Scope

pdca only. Related skills carry no multi-phase blockedBy chain: plan-plus creates a single [Plan] Task (completed by pdca design's new step), cc-version-analysis uses a single Task with subtask tracking, sprint uses per-feature Tasks.

Verification

• New test/regression/issue-137-predecessor-task-completion.test.js — 25/25 assertions (guards the Phase Transition Rule + each per-transition completion instruction; fails if any is removed).
• All static + contract gates green: check-skill-frontmatter, lint-skill-md, check-deadcode (195/0), docs-code-sync (2.1.29 invariant), validate-plugin --strict (0 err), Contract L1/L4 vs v2.1.9 (222) & v2.1.16 (243), integration-runtime 23/23, l2-smoke 105/105, l2-hook-attribution 13/13, invocation-inventory 213/213, docs-code-sync.test 36/36, bkit-full-system 36/36.
• Zero new regressions vs main — qa-aggregate failing-file set is identical to the pre-existing main baseline (13 files).
• Live QA: fresh claude -p … --plugin-dir . process loads the updated skill and reads the new instruction + Phase Transition Rule heading.
• No architecture-count or runtime-behavior change (44 skills / 34 agents / 22 hook events / 195 lib modules unchanged). Version 2.1.28 → 2.1.29; CHANGELOG ## [2.1.29].

Docs = Code

Bilingual PDCA docs (plan/design/analysis/report .en+.ko) + CHANGELOG + marketplace description synced.

🤖 Generated with Claude Code

https://claude.ai/code/session_01W1jmB5L36rnEGjQtH5St9H