STEP-07-C: lint_ticket() pre-flight gate in ticket_io.py

[MrSnowNB]

STEP-07-C — Ticket Lint Gate

Part of: STEP-07 spec
Depends on: #3 (STEP-07-B)

What to build

Add lint_ticket(ticket: Ticket) -> List[str] to src/ticket_io.py.

Lint rules:

• LINT-001 — task references a .py filename but context_files is empty
• LINT-002 — produces/consumes declared but context_files is empty
• LINT-003 — context_files references a file that does not exist on disk
• LINT-004 — task is None or empty string

Call lint_ticket() inside write_tickets() in runner.py:

• Warn (print) on violations — do NOT block ticket write
• Log violations to logs/lint-violations.jsonl

Warn-not-block by design. Hard-fail comes in STEP-08 after false-positive rate measured in real runs.

Gate

pytest tests/test_ticket_io.py -v green. 4+ new tests covering each lint rule.

Files

• src/ticket_io.py
• agent/runner.py
• tests/test_ticket_io.py