Proof Loop

A sprint is not done until every acceptance criterion has a PASS verdict from a fresh verifier session.

Read references/workflow.md for the full loop spec. Read references/brief-template.md for the agent brief format. Read references/artifacts.md for the artifact schema. Read references/loopsmith-bridge.md when deciding whether a repeated Proof Loop failure should become a Loopsmith eval case.

Activation and Safety Boundaries

Use this skill only when the user explicitly asks for Proof Loop, proof artifacts, acceptance-criterion verification, fresh verifier separation, or an evidence-gated coding sprint. Do not activate it for ordinary code edits where the user did not request this protocol.

Proof Loop may create or update files under .agent/tasks/<TASK_ID>/ in the current repository. Confirm the task id and repository root before creating artifacts. Do not publish artifacts, run remote validation, change repository permissions, moderate users, request full-access sandboxing, or touch credentials unless the user explicitly asks for that separate action in the current conversation.

Run helper scripts with the least privilege available. If a command could modify source files outside .agent/tasks/<TASK_ID>/, ask first and record the command in the evidence artifact.

The Loop

spec freeze -> build -> evidence -> FRESH verify -> fix -> FRESH verify
                                         ^                      |
                                         |______________________|
                                         (repeat until all ACs = PASS)

Four Roles — Always Separate

Role	Does	Never
Spec-Freezer	Writes spec.md with explicit ACs	Edits production code
Builder	Implements against frozen spec	Verifies own work
Verifier	Fresh session — verdicts each AC	Edits production code
Fixer	Minimal fix for what verifier flagged	Signs off on completion

The verifier is always a fresh session. The agent that built cannot judge its own work.

Acceptance Criteria Format

Every sprint brief must include explicit ACs before build starts:

AC1: [specific, testable condition — not a task description]
AC2: [specific, testable condition]
AC3: [specific, testable condition]

Good: "AC1: A German-locale user sees all prompt form field labels in German" Bad: "AC1: Translate the form fields"

Helper Scripts

Use these when the repository has the proof-loop folder available:

python3 scripts/init_task.py TASK_ID --title "Task title"
python3 scripts/check_task.py .agent/tasks/TASK_ID

check_task.py is the mechanical done gate. It returns success only when the verifier artifacts show every AC as PASS and no open problems remain.

Sprint is DONE Only When

• Every AC has a PASS verdict in the verifier's verdict.json
• No problems remain in problems.md
• Full regression suite passes (if applicable)

Artifacts (stored in repo)

.agent/tasks/<TASK_ID>/
  spec.md         -- frozen ACs + constraints + non-goals
  verdict.json    -- AC verdicts per phase (PASS/FAIL/UNKNOWN)
  problems.md     -- specific failures with file/line refs (if any)

See references/artifacts.md for schemas.