fix(http-bridge): clean stale inflight session futures

[zvladru]

Problem

The HTTP bridge tracks in-flight session creation futures in _http_bridge_inflight_sessions. If a creation path leaves behind a completed or stale pending future, drain/status can keep reporting an in-flight session create without enough context to explain or recover from it.

That makes graceful maintenance harder: a restart can appear blocked by a stale bridge create rather than by real queued work.

Changes

• Timestamp newly-created HTTP bridge in-flight session futures.
• Add a non-blocking cleanup pass to http_bridge_activity_snapshot_nowait().
• Remove completed in-flight session-create futures from the tracking map.
• Treat very old pending in-flight futures as stale, remove them, and complete them with a capacity-style ProxyResponseError so waiters are released.
• Add snapshot counters for oldest age, stale count, and cleanup count.
• Log structured cleanup diagnostics with bridge kind/key hash, age, threshold, done/cancelled state, and cleanup reason.

Impact

Normal bridge session creation is unchanged. The new path only affects done leftovers or pending futures older than the stale threshold (max(120s, admission_timeout * 6)). Drain/status can now self-heal stale in-flight session-create bookkeeping and explain what was cleaned up.

Tests

• uv run pytest -q tests/unit/test_proxy_http_bridge.py::test_http_bridge_activity_snapshot_counts_pending_and_inflight_sessions tests/unit/test_proxy_http_bridge.py::test_http_bridge_activity_snapshot_cleans_stale_inflight_session tests/unit/test_proxy_http_bridge.py::test_get_or_create_http_bridge_session_inflight_wait_times_out tests/unit/test_proxy_http_bridge.py::test_get_or_create_http_bridge_session_capacity_wait_times_out

[chatgpt-codex-connector]

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Reviewed commit: da7e9f4b2f

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[zvladru]

Addressed the automated review feedback in b895c568 by wiring the HTTP bridge activity snapshot into /internal/drain/status.

@codex review

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: b895c5684f

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[chatgpt-codex-connector]

Keep inflight cleanup under the registry lock

When /internal/drain/status runs while _get_or_create_http_bridge_session is suspended inside _http_bridge_lock on owner/ring/durable awaits, this cleanup can still pop and set exceptions on _http_bridge_inflight_sessions without taking that lock. In that overlap a request that is about to read the inflight future under the lock can instead see it disappear, skipping the terminal inflight error or starting a duplicate bridge create; make this cleanup try-acquire/use the same registry lock, or skip mutation when it cannot.

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