Codex invocations do not handle lifecycle diagnostics reliably #148

Problem

When Codex runs through the conversion route, its JSONL stream includes lifecycle events such as thread.started and turn.started. It can also emit a nonfatal model-catalog refresh diagnostic on stderr and then continue successfully.

The current adapter ignores the lifecycle start events and forwards the full diagnostic response body. The browser also marks a conversion as done whenever the SSE stream ends, even when the agent has a non-zero or missing exit code or produced no HTML. Together, this makes a run look stalled or successful without a reliable terminal state.

Reproduction

1. Run pnpm -F @html-anything/next dev.
2. Select Codex and start any conversion.
3. Observe a lifecycle diagnostic before the assistant output.
4. Observe that completion is not derived from both the process exit code and generated HTML.

Redacted real-session event shape:

thread.started
turn.started
item.completed (diagnostic)
item.completed (agent message)
turn.completed

Expected behavior

• Surface the Codex session and generation start events.
• Treat diagnostic items as warnings rather than generated HTML.
• Preserve useful stderr context while redacting appended response bodies.
• Mark a conversion done only after exit code 0 and non-empty HTML.
• Keep provider and model selection inherited from the existing Codex CLI configuration.