TDD: 4 red-to-green tests reproducing the two review findings + 6 new cases; 30/30 in tests/unit/codex-app-server.test.ts; typecheck/eslint/env-doc-sync/file-size clean. Merged --admin over the inherited 2026-08-23 base-red cluster (#9985): the remaining reds (CLI catalog/registry tests, @testing-library allowlist) are proven tip failures unrelated to this diff — shard logs show only CLI-cluster failures, and this PR itself drains the mutation-test-coverage red (stryker registration for #11267's test). Behavior change for app-server deployments is documented in the PR body (sandbox default + binding refusal).
Merged after conflict resolution: the 5 conflicting test files were the base-red drains that #11201 already landed on the tip — kept the tip versions; the feature content is untouched. Validated on the combined batch board + this branch: codex-app-server + codex-gpt56-catalog 25/25, typecheck:core clean, docs-counts green (351 providers), provider-consistency 268/351/0. The opt-in codex-app-server transport (JSON-RPC-over-WS, turn/completed-awaited close, Responses SSE bridge) leaves the default codex path untouched. Thank you @arminanton — a 3.4k-line transport with the docs wave and tests to match!
