Add activity_hb.join(timeout=2.0) after activity_hb_stop.set() in
direct_api_call's finally block so the heartbeat thread is deterministically
stopped before client teardown. Add test verifying no stray _touch_activity
fires after direct_api_call raises an exception.
Follow-up to PR #78548 by @xxxigm.
Top-level delegate_task runs in the background, and the 450s progress-stall
monitor only sees api_call_count / tool / last_activity_ts. Subagents use
non-streaming direct_api_call, which previously touched activity once and then
went silent — so a healthy local GGUF / long-prefill wait looked frozen and
was interrupted around ~450s as "Operation interrupted: waiting for model
response", even when child_timeout_seconds was raised. Refresh activity while
the inline request is open, and treat last_activity_ts advances as sync
heartbeat progress too.
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.