The HTTP verifier could not distinguish a mis-wired or non-serving app from a
genuine no-effect: both yielded `inconclusive`. This adds a positive control for
the path oracle.
- PathOracle plants a benign in-root marker file (random token from os.urandom,
distinct from the secret canary) and exposes it via a new Oracle.control()
hook (default None; only the path oracle implements it today).
- On the first run of an HTTP side, _side runs a benign GET for that marker as
its own fully-guarded app start. The marker returning proves the interface
serves the fixture; its absence — or any control failure — is recorded in the
new SideRecord.control_observed field but never changes the verdict, since a
valid app may answer only its own routes. A crash is still caught by the
existing could_not_run path.
A 2xx-based "nothing served" block was rejected: the verifier deliberately
treats any HTTP status as the app being alive (a 503-only app is a valid
observed side), so status-based blocking would false-fail valid apps. Soundly
converting a mis-wired-but-responding app into could_not_run requires a
demo-declared control, which is a separate follow-up.
Tests: new tests/test_search_control.py covers marker observed, absent marker
not blocking, control failure not blocking a working attack, and crash still
could_not_run. Full search-verify/probe/worker suites pass; ruff clean; mypy
unchanged (only the pre-existing file_bindings lambda note).
Co-Authored-By: Claude Opus 4.8 <[email protected]>
