Best possible solution:

Keep the lease-scoped redacted stderr-tail design, remove or explicitly justify sandbox policy inheritance from isolated Codex config, then land after redacted installed-path proof shows the actionable stderr tail in the sessions_spawn flow.

Do we have a high-confidence way to reproduce the issue?

Yes at source level: current main's generated Codex wrapper does not retain stderr and ACPX ensureSession/runTurn paths pass through generic Internal error failures without a retained stderr tail. I did not establish a live installed-gateway reproduction in this read-only review.

Is this the best way to solve the issue?

Mostly yes, but not as submitted: lease-scoped redacted stderr tails are a narrow maintainable fix for opaque generic Codex ACP failures. The sandbox policy inheritance should be removed or handled through an explicit OpenClaw-owned policy contract before merge.

Full review comments:

• [P1] Stop inheriting Codex sandbox policy — extensions/acpx/src/codex-trust-config.ts:166
  This whitelist is described as copying safe model/provider routing into the isolated CODEX_HOME, but sandbox_mode is execution policy, not routing. If a host Codex config uses a broader value such as danger-full-access, ACP child sessions now silently inherit that permission posture even though the current ACP docs say isolated Codex config only carries trusted project entries. Keep the model/provider keys, but leave sandbox policy out unless OpenClaw has an explicit policy path for it.
  Confidence: 0.86

Overall correctness: patch is incorrect
Overall confidence: 0.86

Security concerns:

• [medium] Sandbox policy is inherited as routing config — extensions/acpx/src/codex-trust-config.ts:166
  Adding sandbox_mode to the inherited Codex config whitelist moves host Codex execution policy into ACP child sessions. That can change sandbox strength without an explicit OpenClaw policy decision, so it should be removed or separately approved and documented.
  Confidence: 0.86

What I checked:

• Current main lacks retained wrapper stderr: Current main generates the Codex ACP wrapper with inherited stdio and no per-lease stderr log for later diagnostic decoration. (extensions/acpx/src/codex-auth-bridge.ts:224, 926bf66ee336)
• Current main passes through generic turn errors: Current main's ACPX runtime delegates runTurn directly, so generic ACP terminal errors are not enriched from wrapper stderr on that path. (extensions/acpx/src/runtime.ts:894, 926bf66ee336)
• PR captures Codex wrapper stderr: PR head changes the generated wrapper to pipe child stderr, append redacted text to a per-lease log, mirror stderr, and flush before process exit. (extensions/acpx/src/codex-auth-bridge.ts:480, e29c6d89ac7c)
• PR decorates generic Codex ACP failures: PR head adds bounded stderr-tail reads and wraps generic Internal error failures during session initialization and turn error paths. (extensions/acpx/src/runtime.ts:818, e29c6d89ac7c)
• Focused tests cover stderr decoration: PR head adds regression coverage for session-init stderr decoration, first-turn thrown failures, terminal error events, and generated-wrapper stderr redaction, but this remains test-harness proof. (extensions/acpx/src/runtime.test.ts:244, e29c6d89ac7c)
• Security-sensitive config inheritance: PR head includes sandbox_mode in the inherited Codex config whitelist and tests that it is copied, even though the stated safe-copy scope is model/provider routing. (extensions/acpx/src/codex-trust-config.ts:166, e29c6d89ac7c)

Likely related people:

• steipete: Recent current-main history repeatedly touches ACPX runtime, Codex wrapper/auth isolation, process leases, and bundled ACP adapter behavior central to this PR; the current PR head commit is also authored by this account with contributor co-author credit. (role: recent ACPX area contributor; confidence: high; commits: 42ecd5d95eae, d3e4640bedf5, 137a3629cc7f; files: extensions/acpx/src/runtime.ts, extensions/acpx/src/codex-auth-bridge.ts, extensions/acpx/src/process-lease.ts)
• vincentkoc: Recent merged history includes ACP-only field handling at the sessions_spawn boundary adjacent to the acp-spawn behavior and tests touched here. (role: sessions_spawn ACP contributor; confidence: medium; commits: efc3a52947e9; files: src/agents/acp-spawn.ts)
• hexsprite: Recent merged history preserved ACP runtime error detail across lifecycle boundaries, adjacent to this PR's diagnostic error-surfacing behavior. (role: adjacent ACP error propagation contributor; confidence: medium; commits: 86c1622a3a3c; files: src/agents/acp-spawn.ts, src/acp/runtime/errors.test.ts)

Remaining risk / open question:

• No redacted installed-gateway proof currently shows the patched sessions_spawn(runtime="acp", agentId="codex") path surfacing the stderr tail.
• The linked bug also includes Discord reply delivery behavior, which this diagnostic PR does not by itself prove fixed.
• The sandbox_mode inheritance needs removal or explicit maintainer approval because it changes ACP child process permission policy.

Codex review notes: model gpt-5.5, reasoning high; reviewed against 926bf66ee336.