S5.2-analog. New notify.py: Notifier protocol + console/file/webhook sinks. The
webhook (the one transport that leaves the machine) fires ONLY behind an explicit
per-run opt-in flag (--allow-webhook-egress), mirroring ingest-spec §8 (the flag
is a run argument, never a config field). Transport is injected — canned in the
suite (NULL socket), real transport behind one seam function default_webhook_transport;
an AST grep-guard proves no network path exists outside that seam. run.py (both
outcomes — a budget stop notifies too) and hitl.py (read-only preserved) share the
same opt-in-gated CLI seam, refusing a webhook-without-opt-in before any spend.
Payload shape is stack-local (no shared notification spec; divergence documented).
Two new load-bearing test files (18 tests): opt-in gate + payload structure + the
grep-guard + run/hitl emit wiring + run-level opt-in threading, each detach-proven
RED. 544 -> 562 green, full gate clean (ruff+format+mypy strict, 26 src files).
README sync (test count x2 + notify.py module note + load-bearing omtale).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RiTwaKLesgcwXx2mDviqpt
