Issue 11873 reproduction, Ubuntu 24.04 x86_64, Node 24.21.0, Codex CLI 0.163.0
Initial main: 3b95e7831b

Real web dev app (vp run dev), isolated /home/ubuntu/wt/issue-11873/.t3
Seeded stopped threads copied from read-only snapshot by the dev runner.
Provider home: fresh empty directory, no auth.json.
Launch arguments:
-c model_providers.cliproxy.name="cliproxy"
-c model_providers.cliproxy.base_url="http://127.0.0.1:8317/v1"
-c model_providers.cliproxy.env_key="ANTHROPIC_AUTH_TOKEN"
-c model_providers.cliproxy.wire_api="responses"
-c model_provider="cliproxy"
Environment key: public fixture value triage-fixture-key, not a real credential.
No proxy/model request is needed to reach this failure.

Opened /usage, selected Limits.
Observed: Codex (via cliproxy): Codex could not read usage (JSON-RPC -32600).

Separate real codex app-server stdio handshake with the same launch arguments:
initialize result: userAgent T3 Code/0.163.0 (Ubuntu 24.4.0; x86_64)
account/read params {}:
{"id":2,"result":{"account":null,"requiresOpenaiAuth":false,"workspaceRouting":null}}
account/rateLimits/read params null:
{"id":3,"error":{"code":-32600,"message":"codex account authentication required to read rate limits"}}

Red test commit 951a245da8, ProviderRegistry.test.ts:
Expected { reason: "unsupported" }
Received { reason: "probeFailed", message: "Codex could not read usage (JSON-RPC -32600)." }

Final narrow classifier recognizes the typed request error tag, exact code and exact message;
only the null-account/no-required-auth state becomes unsupported. Other errors remain probeFailed.