Pipeline integrity + brownfield adoption system

Pipeline integrity (4 fixes for snapshot-vs-live-reference problem):
- NEW docs/architecture/tr-registry.yaml: persistent stable TR-IDs per GDD
  requirement; /architecture-review bootstraps and appends, never renumbers
- /create-control-manifest: added Manifest Version stamp to header
- /create-epics-stories: stories embed TR-ID reference (not quoted text),
  Manifest Version from manifest, ADR status gate (Proposed → Blocked)
- /story-done: TR-ID registry lookup at review time, manifest staleness check
- /story-readiness: ADR Accepted check, TR-ID validity, manifest version check
- /review-all-gdds + /architecture-review: fixed parenthetical status values
  ("Needs Revision" only, no parentheticals that break exact-match reads)

Workflow infrastructure:
- NEW /help skill: context-aware "what's next" using workflow-catalog.yaml
- NEW .claude/docs/workflow-catalog.yaml: YAML-driven phase/step sequence
- /sprint-plan + /sprint-status: sprint-status.yaml machine-written tracking

Brownfield adoption system (migrate, not replace):
- NEW /adopt skill: format compliance audit (not existence check); classifies
  gaps BLOCKING/HIGH/MEDIUM/LOW; produces docs/adoption-plan-[date].md with
  numbered migration plan; never regenerates existing artifacts
- /design-system retrofit [path]: fills only missing GDD sections, preserves
  all existing content
- /architecture-decision retrofit [path]: adds missing ADR sections (Status,
  ADR Dependencies, Engine Compatibility) without touching existing content
- /start option D: split into D1 (early-stage) and D2 (has GDDs/ADRs → adopt)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/skills/architecture-decision/SKILL.md

@@ -8,6 +8,53 @@ allowed-tools: Read, Glob, Grep, Write
 
 When this skill is invoked:
 
+## 0. Parse Arguments — Detect Retrofit Mode
+
+**If the argument starts with `retrofit` followed by a file path**
+(e.g., `/architecture-decision retrofit docs/architecture/adr-0001-event-system.md`):
+
+Enter **retrofit mode**:
+
+1. Read the existing ADR file completely.
+2. Identify which template sections are present by scanning headings:
+   - `## Status` — **BLOCKING if missing**: `/story-readiness` cannot check ADR acceptance
+   - `## ADR Dependencies` — HIGH if missing: dependency ordering breaks
+   - `## Engine Compatibility` — HIGH if missing: post-cutoff risk unknown
+   - `## GDD Requirements Addressed` — MEDIUM if missing: traceability lost
+3. Present to the user:
+   ```
+   ## Retrofit: [ADR title]
+   File: [path]
+
+   Sections already present (will not be touched):
+   ✓ Status: [current value, or "MISSING — will add"]
+   ✓ [section]
+
+   Missing sections to add:
+   ✗ Status — BLOCKING (stories cannot validate ADR acceptance without this)
+   ✗ ADR Dependencies — HIGH
+   ✗ Engine Compatibility — HIGH
+   ```
+4. Ask: "Shall I add the [N] missing sections? I will not modify any existing content."
+5. If yes:
+   - For **Status**: ask the user — "What is the current status of this decision?"
+     Options: "Proposed", "Accepted", "Deprecated", "Superseded by ADR-XXXX"
+   - For **ADR Dependencies**: ask — "Does this decision depend on any other ADR?
+     Does it enable or block any other ADR or epic?" Accept "None" for each field.
+   - For **Engine Compatibility**: read the engine reference docs (same as Step 0 below)
+     and ask the user to confirm the domain. Then generate the table with verified data.
+   - For **GDD Requirements Addressed**: ask — "Which GDD systems motivated this decision?
+     What specific requirement in each GDD does this ADR address?"
+   - Append each missing section to the ADR file using the Edit tool.
+   - **Never modify any existing section.** Only append or fill absent sections.
+6. After adding all missing sections, update the ADR's `## Date` field if it is absent.
+7. Suggest: "Run `/architecture-review` to re-validate coverage now that this ADR
+   has its Status and Dependencies fields."
+
+If NOT in retrofit mode, proceed to Step 0 below (normal ADR authoring).
+
+---
+
 ## 0. Load Engine Context (ALWAYS FIRST)
 
 Before doing anything else, establish the engine environment: