fix: prevent agent loop deadlock when LLM response is silently dropped (#72940)

[webtecnica]

Summary

Fixes #72940 — agent loop deadlock where a valid LLM response is received but silently dropped, leaving the session stuck with no output and no tool calls.

Root Cause

When should_use_direct_api_call() returns True (cron turns, delegated children, subagent platform), the conversation loop calls direct_api_call() to issue synchronous LLM requests. After the API request completes successfully, this function checked agent._interrupt_requested and raised InterruptedError — discarding the valid response.

The worker-based path (interruptible_api_call) does NOT have this post-response interrupt check: it only checks for interrupts during its polling loop while the background thread is still alive. Once the thread finishes, the response is returned unconditionally. direct_api_call should behave the same way.

The conversation loop's own redirect/finally handling (in conversation_loop.py) already catches pending redirects via the _redirect_crossed_response mechanism before response processing begins, so the duplicate check in direct_api_call was both redundant and harmful.

The Fix

Removed the _interrupt_requested check from the success path of direct_api_call(). A valid response is now always returned to the conversation loop, which handles interrupts and redirects through its own established mechanisms.

Testing

• The except-path interrupt check is preserved — if the API call fails and the interrupt flag is set, it still raises InterruptedError as before
• The worker-based path is unchanged
• The conversation loop's redirect handling (_redirect_crossed_response in the finally block of _perform_api_call) continues to work independently

[alt-glitch]

This was generated by AI during triage.

This PR contains the complete pinned-session sync patch already proposed by #72953, plus an independent direct-call interruption hunk for #72940. Please split and rebase the agent-loop change; the bundled pin-sync portion duplicates #72953.

[webtecnica]

Closing as requested by triage — this PR bundles #72953 (pinned sessions sync) which is its own PR. The independent agent-loop deadlock fix (#72940) should be submitted as a focused PR. See alt-glitch comment.