PR #24015 runtime verification
main: 36aea583bb
PR: 6328c3fa6f616d56ba4b340062e0cc66973bcb06
Linux, actual dev web client, Google Chrome + repo Playwright
Provider: released @zed-industries/codex-acp 0.16.0, no mocks or injected stderr

Reproduction: add Local ACP provider in Settings pointing to real codex-acp executable, CODEX_HOME=/tmp/acp-verify-home. Complete a gpt-6.1-sol turn. Set model_provider in isolated config to synthetic key-shaped names plus diagnostic_marker. Start a new thread from the web client and submit a message. The real ACP executable exits 1 and emits the unknown-provider diagnostic.

MAIN server error excerpt:
      '        Error: error loading config: Model provider `[redacted]AbCdEf_GhIjKlMnOpQrStUvWxYz-AA sk-proj-AbCdEfGhIj_KlMnOpQrStUvWxYz [redacted] [redacted] diagnostic_marker` not found\n' +

PR server error excerpt:
      '        Error: error loading config: Model provider `[redacted] [redacted] [redacted] [redacted] diagnostic_marker` not found\n' +

Persisted server.trace.ndjson: main has 17 diagnostic events; synthetic OpenAI key and Anthropic body present. PR has 13 diagnostic events; neither key/body present. All PR excerpts retain diagnostic_marker and redact all four values.

Nearby behavior: real gpt-6.1-sol turns passed using native Codex and codex-acp on both revisions. On PR, restoring valid config and submitting again in the SAME failed thread returned ACP recovery ok. ghp_ and xoxb- values remain redacted on both revisions. Expanded client error contains no synthetic keys.

Blacksmith: vp test run packages/provider-acp/src/server/stderr.test.ts: 3 passed.
No source changes.