# Bug: Automations fail with `invalid_prompt` on OpenRouter provider (Responses wire API)

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

Environment - Codex Desktop on Windows 11, CLI version 0.151.0-alpha.7.2 - Provider config: model_provider = "openrouter", base_url = "https://openrouter.ai/api/v1", wire_api = "responses" - Models tested: z-ai/glm-5.3-flash, moonshotai/kimi-k3 — both fail identically

What subscription do you have?

openrouter

What platform is your computer?

No response

What issue are you seeing?

Symptom

All scheduled automations (2 cron + 1 heartbeat) trigger on time but every run terminates within ~4 seconds, before any business logic executes. The task_complete event carries:

{"error":{"code":"invalid_prompt","message":"Invalid Responses API request"}}

This has failed on every scheduled run since at least 2026-09-02 (multiple CLI versions). Changing the automation's model does NOT help — the same failure occurs on every OpenRouter-backed model.

Root cause (from session logs)

The Zod validation error is at input item index 2:

branch 0: Invalid input: expected string, received array
branch 1: input[2]: Invalid input | input[13]: Invalid input | ...

Item 2 in the automation's initial context is a function_call_output injected by Codex itself, for the codex_app/automation_update tool:

{"type":"function_call_output","id":"fco_...","name":"automation_update","namespace":"codex_app","output":"..."}

This item fails OpenRouter's Responses API schema validation. The same models work fine in normal interactive sessions (which don't contain this injected item), so the issue is specifically the automation-context serialization vs. OpenRouter's Responses validation.

Expected behavior

Automations should run on OpenRouter-backed models, or the injected automation_update function_call_output should be serialized in a shape that passes Responses validation (or omitted from the request).

Reproduction

1. Configure Codex with OpenRouter as model provider (wire_api = "responses").
2. Create any automation (cron or heartbeat).
3. Wait for a scheduled run — it fails immediately with invalid_prompt.

Logs

Happy to attach full rollout JSONL from ~/.codex/sessions/ on request.

What steps can reproduce the bug?

Configure Codex with OpenRouter as model provider (wire_api = "responses").

Create any automation (cron or heartbeat).

Wait for a scheduled run — it fails immediately with invalid_prompt.

What is the expected behavior?

No response

Additional information

No response

Start with the automation context and Responses wire API path, tracing the reported function_call_output at input item index 2 and comparing it with the validation error. Reproduce with OpenRouter using wire_api = "responses" and inspect the rollout JSONL under ~/.codex/sessions/; done means scheduled automations complete successfully without invalid_prompt.