Ships PR #6757 with a maintainer hardening pass folded in (authorship preserved).
Preserves the exact provider-facing reply text (api_content) through the internal
session store for byte-accurate agent replay, while guaranteeing it never reaches
a browser: every client-facing surface strips it via the public projection.
Maintainer fixes (2 defects my adversarial re-gate reproduced):
- Selective session redaction restored: only transcript fields are scrubbed;
operational fields (e.g. workspace path) pass through unchanged, so a path
containing credential-shaped text is no longer masked into an invalid path.
- Runner-backed SSE relay now projects payloads before emit, closing an
api_content leak through _stream_runner_run_events.
+5 regression tests. Codex adversarial re-gate: SAFE TO SHIP. Full suite clean.
Co-authored-by: franksong2702 <franksong2702@users.noreply.github.com>