[macOS][MCP OAuth] Keyring write fails with Platform secure storage failure: UNIX[Operation not permitted]

What version of the Codex App are you using (From “About Codex” dialog)?

Codex app 26.820.60940 (bundle build 7119). The bundled Codex CLI reports 0.150.0-alpha.8.

A separate PATH-installed CLI on the same host reports 0.139.0. The earlier sanitized failure receipt did not retain which binary emitted the error, so this report does not claim a more precise failing-binary identity.

What subscription do you have?

Not inspected.

What platform is your computer?

macOS 26.5.2 (build 25F84), Apple Silicon (arm64).

What issue are you seeing?

During a supported MCP OAuth login flow, Codex failed while trying to persist OAuth material to secure storage:

failed to write OAuth tokens to keyring: Platform secure storage failure: UNIX[Operation not permitted]

The login did not produce a usable authenticated connector. No token or other OAuth secret is included in this report.

The host config has no explicit mcp_oauth_credentials_store override, so the documented auto setting applies. The official config reference lists only auto | file | keyring. File-based credential storage is not an acceptable secure fallback for this environment.

What steps can reproduce the bug?

The exact prior sequence was preserved without secrets:

1. On the macOS Codex host, configure an existing streamable-HTTP MCP server that uses OAuth.
2. Start the supported Codex MCP login flow.
3. Verify the intended authorization endpoint and the local callback setup.
4. Allow Codex to continue until it tries to persist the OAuth material.
5. Observe the keyring write failure above.
6. Confirm that the connector is not usable after the failure.

The failed workflow used Codex's supported MCP login path. No manual Keychain access, credential-store inspection, raw token, alternate profile, or custom persistence helper was used.

What is the expected behavior?

Codex should persist MCP OAuth credentials in the macOS Keychain when mcp_oauth_credentials_store = "auto" selects secure storage. If secure persistence is unavailable, Codex should return an actionable typed error and a supported secure recovery path without consuming another OAuth attempt.

Additional information

• The app bundle identifier is com.openai.codex.
• The installed bundled Codex binary SHA-256 is 4ff5e75f028e913cfeb53bd7319f87573cdce6538c1b1ccc44ce62d5ce51ca1d.
• The app and bundled binary were installed before the observed failure.
• Two bounded authorization attempts were consumed by the calling workflow. A third attempt is intentionally blocked until secure persistence is repaired or another supported secure persistence path exists.
• Exact-duplicate searches for Platform secure storage failure: UNIX[Operation not permitted] found no matching issue.
• Related but distinct reports include #38691 (noninteractive Keychain access from detached app-server processes) and #36453 (username/passphrase secure-storage failure). This report concerns the exact UNIX Operation not permitted failure on the active Codex macOS host.