SDLC Checkpoint Skill

Goal

Create durable snapshots at each SDLC gate so the project can be resumed, audited, or rolled back to any milestone. Verify all gate criteria before advancing to the next phase.

SDLC Phases

Steps

1. Identify which phase is completing

   • Determine the phase number (S01-S10) from current context
   • Retrieve the gate criteria for this phase from the table above

2. Verify gate criteria are met

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   S01 gate check:
   [ ] PRD.md exists with EARS-formatted requirements
   [ ] No unresolved ambiguities in requirements
   [ ] Human has explicitly approved the PRD
   
   S02 gate check:
   [ ] PLAN.md or architecture document exists
   [ ] C4 diagrams exist in docs/architecture/ (or documented reason for exception)
   [ ] ADR created for any significant technology decision
   [ ] Threat model created for security-sensitive features
   
   S05 gate check:
   [ ] All tasks in project/tasks.md have status: DONE (none TODO, IN_PROGRESS, or BLOCKED)
   [ ] No task has "pending human decision" that hasn't been resolved
   
   S06 gate check:
   [ ] All tests passing: [run test command, confirm green]
   [ ] Coverage >= 96%: [run coverage command, confirm threshold]
   [ ] Lint: zero errors
   [ ] Typecheck: zero errors
   [ ] agentic-linter: no architecture violations
   
   S07 gate check:
   [ ] templates/security/SECURITY_CHECKLIST.md fully completed
   [ ] No critical CVEs in dependency audit
   [ ] All High/Critical threats from threat model have mitigations implemented
   

3. If gate criteria NOT met

   • List what is missing
   • Do NOT advance to next phase
   • Report to human: "Phase [X] checkpoint cannot be created — gate criteria not met: [list]"

4. Create the SESSION_SNAPSHOT (when gate criteria are met)

   Write file: agents/memory/episodic/SESSION_SNAPSHOT/S0[X]_[phase-name].md

   Content:

   markdownCopy

   # Snapshot S0[X] — [Phase Name]
   Timestamp: [ISO 8601 datetime]
   Phase: S0[X]
   Created by: [agent persona or "human"]
   
   ## What Was Decided / Built
   [Summary of key decisions and artifacts produced in this phase]
   
   ## Artifact Status
   - PRD.md: [✓ exists / ✗ missing]
   - PLAN.md: [✓ exists / ✗ missing]
   - project/tasks.md: [✓ exists / N/M tasks done]
   
   ## Test Status
   - Last run: [timestamp]
   - Pass: [N] | Fail: [0] | Skip: [0]
   - Coverage: [X]%
   
   ## Security Status
   - Last audit: [timestamp or N/A]
   - Open CVEs: [0 critical, 0 high]
   - SECURITY_CHECKLIST: [X]% complete
   
   ## Key Decisions Made This Phase
   - [decision 1 with rationale]
   - ADRs created: [list]
   
   ## Open Issues / Known Debt
   - [any unresolved issues that the NEXT phase should be aware of]
   
   ## Gate Criteria Verified
   [✓] [criterion 1]
   [✓] [criterion 2]
   
   ## Next Phase Entry Criteria
   [what needs to happen to start the next phase]
   

5. Update PROJECT_STATE.md

   • Change current phase to the NEXT phase (or mark project complete at S10)
   • Update "Last checkpoint" timestamp and phase
   • Clear "Current Blockers" if resolved

6. Write to AUDIT_LOG.md

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   | [timestamp] | [session] | [agent] | PHASE_TRANSITION | S0[X] [Phase] checkpoint created | SUCCESS | episodic/SESSION_SNAPSHOT/S0[X]_[name].md |
   

7. Tag git commit

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   git tag checkpoint/S0[X]-[phase-name] -m "SDLC checkpoint: [phase] completed"
   # Note: only tag if working directory is clean (all changes committed)
   

Constraints

• NEVER create a checkpoint if gate criteria are not met
• NEVER advance to next phase without human approval at S01, S02, S07, S08
• Snapshots are immutable — never overwrite a snapshot file (create a new one if re-doing a phase)
• Git tag must match snapshot filename for traceability

Output Format

Created snapshot file path + updated PROJECT_STATE.md + AUDIT_LOG.md entry + git tag. Report: "Checkpoint S0[X] created. Next phase: S0[X+1]."