Root cause: delegate_task children run through three nested daemon-thread
layers (async-delegation executor -> per-child timeout executor -> the
interrupt worker interruptible_api_call spawns). After multi-day gateway
uptime the deepest layer wedges BEFORE the socket opens — the same
fingerprint as the gateway-cron hang (#62151): zero stale-detector output
(the worker never reaches dispatch), all providers, foreground/restart
works. The cron fix (should_use_direct_api_call) explicitly excluded
delegation 'for lack of evidence' — #60203 is that evidence.
- should_use_direct_api_call: extend the inline gate to delegated
children, detected via the delegation ContextVar set by
_run_single_child (platform='subagent' stamp as fallback). Scope
unchanged otherwise: chat_completions wire only; Codex/Anthropic/
Bedrock/MoA keep their established workers. Interrupts still work —
the inline path registers _active_request_abort, which interrupt()
invokes cross-thread (same mechanism the #72227 stall monitor uses).
- _dump_subagent_timeout_diagnostic: dump ALL thread stacks (bounded,
40), not just the conversation worker — a pre-HTTP wedge is
indistinguishable from a slow provider without seeing where the
nested helper threads sit.
