build — implement spec

Single-thread native plan→execute. You are main Claude. No swarm.

LOAD

1. Read SPEC.md. If missing → tell user to invoke the spec skill first. Stop.
2. Read FORMAT.md once if not loaded.
3. Parse invocation args:
   • §T.n → that task only
   • --next → lowest-numbered row with status . or ~
   • --all or empty → every . row in §T order

PLAN

Native plan mode. For chosen task(s):

1. Cite every §V invariant that applies. Plan must respect all.
2. Cite every §I interface touched. Plan must preserve shape.
3. List files to create / edit.
4. List tests to add or update (one per invariant touched).
5. Name verification command (test, build, lint).

Show plan. Wait for user OK unless auto mode.

EXECUTE

Per task in order:

1. Flip §T.n status cell . → ~. Just write to SPEC.md.
2. Edit code per plan.
3. Run verification command.
4. Pass → flip ~ → x. Next task.
5. Fail → invoke backprop skill. Do NOT retry blindly.

FAIL → BACKPROP

On test/build failure:

1. Read failure output.
2. Ask: is failure (a) my code bug, (b) spec wrong, or (c) unspecified edge case?
3. If (a) → fix code, re-run. No spec change.
4. If (b) or (c) → invoke spec skill with bug: <cause> first, let it update §V and §B, then resume build against updated spec.

Rule: never silently fix root-cause without considering backprop. §B is the memory that stops recurrence.

WRITE POLICY

• Only flip §T status. No other SPEC.md edits from build.
• Other spec edits → invoke spec skill.
• Commit after each §T completes. Message: T<n>: <goal line> + §V cites.

VERIFICATION

Task x only if:

• Verification command exits 0.
• New test(s) added per plan.
• No §V invariant regressed (run full test suite at end).

NON-GOALS

• No sub-agents. No parallel workers. Main thread only.
• No progress dashboards. cat SPEC.md | grep §T is the dashboard.
• No speculative work beyond chosen task scope.