AC Lock Checkpoint

Runs automatically as Phase 4.0, after Tasks Validation and before the first implementation task. Purpose: give the user one final explicit confirmation that the Acceptance Criteria represent what they actually want — before any implementation begins.

Position in flow

[Tasks Validation]
      ↓
[AC Lock Checkpoint]  ← THIS SKILL
      ↓
Per-Task: implementation

Entry conditions

• prd.md, techspec.md, and tasks.md must exist in tasks/prd-{slug}/
• Generates accepted-criteria.md in .claude/feature-state/{slug}/
• If accepted-criteria.md already exists (resume case): skip extraction, ask user to confirm current locked ACs or unlock to re-confirm
• Implementation must not start until this file is saved

---

Step 1: Extract and Consolidate ACs

Sources

Read ACs from all three documents:

From prd.md:

• "Goals" or "Objectives" section (functional success criteria)
• "Acceptance Criteria" section (if present)
• "Success Metrics" section (if present)

From techspec.md:

• "Validation & Testing Plan" section
• "Acceptance Criteria" section (if present)
• Non-functional requirements that can be verified

From tasks.md:

• "Acceptance Criteria" or "Done When" column/field per task
• Any inline criteria in task descriptions

Deduplication

Merge near-duplicate ACs (same intent, slightly different wording):

• "trainerId is saved to Firestore" + "trainerId is persisted on student document" → consolidate as one
• Use the more specific/verifiable version

Classification

Group ACs into three categories:

1. Functional — observable user/system behavior

   • e.g., "Trainer can see their connected students in /cms/students"

2. Technical — implementation-level verifiable criteria

   • e.g., "POST /api/students saves trainerId field"
   • e.g., "Firestore security rules validated"

3. Quality — non-functional, cross-cutting

   • e.g., "All use cases have unit tests"
   • e.g., "No breaking changes to existing API consumers"

---

Step 2: Present to User

Present the consolidated list with clear formatting before any implementation starts:

✋ AC Lock Checkpoint — Confirm Before Implementation

This feature will be considered DONE when all of the following are true:

**Functional**
1. [ ] Personal trainer can see all linked students in /cms/students
2. [ ] Student appears in trainer's list after successful Firestore connection
3. [ ] trainerId is persisted on student document in Firestore

**Technical**
4. [ ] POST /api/students saves trainerId field from auth context
5. [ ] GET /api/students filters by authenticated trainer's uid
6. [ ] Firestore security rules allow trainer to read their students only

**Quality**
7. [ ] All new use cases have unit tests
8. [ ] No breaking changes to existing /api/students consumers

---

Does this accurately capture what you want?

  yes           → Lock these ACs and start implementation
  adjust N      → Edit AC number N (e.g., "adjust 3")
  add           → Add a missing AC
  remove N      → Remove AC number N
  show-sources  → Show which document each AC came from

---

Step 3: Interactive Adjustment

Allow the user to modify the AC list before locking:

"adjust N" — edit one AC

Current AC-3: "trainerId is persisted on student document in Firestore"
New AC-3: [user input]

Replace the AC in the list and re-present the relevant section.

"add" — add a missing AC

Enter new AC (describe what must be true when the feature is done):
[user input]

Category: functional / technical / quality?

Append to the appropriate category.

"remove N" — remove an AC

Removing AC-5: "GET /api/students filters by authenticated trainer's uid"
Are you sure? This requirement won't be tracked. (yes/no)

"show-sources" — show provenance

AC-1 → prd.md: Goals section
AC-4 → techspec.md: Validation & Testing Plan
AC-7 → tasks.md: Task 6 - "Done When" criteria

---

Step 4: Lock and Persist

After user confirms with yes:

Save to .claude/feature-state/{slug}/accepted-criteria.md:

## Accepted Criteria — Locked

Feature: {slug}
Locked: {timestamp}
Locked by: user confirmation

> ⚠️ This file is immutable during implementation.
> Do not edit after locking.

### Functional
- [ ] AC-1: Personal trainer can see all linked students in /cms/students
- [ ] AC-2: Student appears in trainer's list after successful Firestore connection
- [ ] AC-3: trainerId is persisted on student document in Firestore

### Technical
- [ ] AC-4: POST /api/students saves trainerId field from auth context
- [ ] AC-5: GET /api/students filters by authenticated trainer's uid
- [ ] AC-6: Firestore security rules allow trainer to read their students only

### Quality
- [ ] AC-7: All new use cases have unit tests
- [ ] AC-8: No breaking changes to existing /api/students consumers

### Sources
| AC | Source |
|----|--------|
| AC-1 | prd.md: Goals |
| AC-4 | techspec.md: Validation & Testing Plan |
| AC-7 | tasks.md: Task 6 |

---

Step 5: PR Coverage Verification

During Phase 5 (Commit & PR), read accepted-criteria.md and check which ACs are covered:

Coverage check

For each AC, check if implementation tasks have been completed that address it:

• Match tasks marked ✅ in the task list against AC keywords
• Mark covered ACs as [x] in the coverage report

PR description includes

## Definition of Done

**Covered by this PR:**
- [x] AC-1: Personal trainer can see all linked students in /cms/students
- [x] AC-2: Student appears in trainer's list after Firestore connection
- [x] AC-4: POST /api/students saves trainerId field

**Known gaps (not covered):**
- [ ] AC-7: Unit tests — partial (3 of 5 use cases tested)

> Full AC list: .claude/feature-state/{slug}/accepted-criteria.md

If all ACs are covered → no "Known gaps" section.

---

Behavior Summary

State	Behavior
accepted-criteria.md does not exist	Run full AC Lock flow
File exists, --resume flag	Show locked ACs, ask to confirm or unlock
File exists, --force-relock flag	Re-run extraction, allow new confirmation
User skips (emergency)	Warn, log "AC Lock bypassed", proceed without file

Emergency bypass

If the user explicitly wants to skip AC Lock (e.g., rapid prototype):

⚠️ AC Lock bypassed — implementation will proceed without locked ACs.
   PR will not include a "Definition of Done" section.
   Type "skip-ac-lock" to confirm.

Log the bypass in .claude/feature-state/{slug}/checkpoint.json.