[nikita-ashihmin]

Summary

When the Codex app-server reports an error with willRetry: true, codex-acp publishes an AIR sessionFailure warning. The warning had only the title, such as Reconnecting... 2/5. Codex puts the cause of the retry in TurnError.additionalDetails, for example stream disconnected before completion: idle timeout waiting for websocket. codex-acp dropped it, so a user saw the same title for minutes and did not know why.

Changes

• recordRetryWarning passes the trimmed additionalDetails as details of the warning. With null or a blank value, the warning has no details key.
• recordSessionFailure takes an optional details. Each revision builds the record again, so a later revision without a cause does not keep the old one.
• Both paths of a retry warning use it: createErrorEvent and handleSessionScopedNotification.
• The title, the actions, the id and the revision do not change.
• Terminal failures (willRetry: false) still do not send additionalDetails. The earlier tests asserted that a retry warning also must not send it. This change removes that rule for retry warnings only. The legacy, non-typed path already sends the full error, additionalDetails included.

Why the cause is safe to send for a retry

PR #383 kept additionalDetails out of every typed failure. This PR changes that rule for retry warnings only. Terminal failures still send no details.

• The cause goes to the same user whose Codex session retries. A user who uses Codex directly sees the same text.
• The legacy, non-typed path already sends the full error to every other client, additionalDetails included.
• For an HTTP retry, the text can hold the response body, the provider URL and a request id. These belong to the user's own account and gateway. They help the user see why the turn waits.

Tests

• auth-error-events.test.ts: the cause is in details for a retry of the current turn, of another turn, of an HTTP 429, and for a late retry after the turn. No details key for null and for a blank value.
• typed-session-failure-wire.test.ts: the raw wire JSON for one id across 4 revisions. A new cause replaces the old one, and a revision without a cause has no details.
• npm run typecheck: clean.
• npm run test: 2507 passed. 2 tests in standard-subagent-live.test.ts fail. They fail on main without this change too.