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plat 678
| Field | Value |
|---|---|
| State | fixed on main |
| Priority | P0 |
| Product | browser |
| Area | browser |
| Summary | A nested lock in the extension reader (PLAT-643) deadlocked the browser relay on RTS; every browser and tool call hung for 58 minutes |
RTS, 2026-10-07, release 7d48e5e (deployed 08:45 UTC, server started 08:48). From about 08:50 the browser relay
stopped; from about 09:15 no coding-agent tool call got through (all mcp__api-bridge__* tools timed out with
MCP error -32001), across the owner's Code chat and workflow runs. The UI and the workspace server stayed healthy.
ai-work-42 took a goroutine dump (/tmp/rts-goroutines.txt, logs/agent-sigquit-20261007.log) and restarted the server
at 09:47.
PLAT-643 (7fceb609b) recorded the extension's version in the extension reader's diagnostic case with
b.mu.Lock()/Unlock(). That whole switch already runs under b.mu (locked before the switch, unlocked after it),
and Go mutexes are not reentrant. The first versioned diagnostic (sent right after pairing) made the reader goroutine
wait on a lock it held (goroutine 1232 at relay.go:722, 58 minutes). The next Manager.Status took the manager lock
and waited on that binding lock (goroutine 1225, relay.go:361 → 377), and then everything needing the manager lock
queued behind it: 1,390 /api/browser/extension status polls, 128 at relay.go:589, browser tool calls
(relay.go:356 via the extension executor) and session cleanups (conversations.go:156).
The existing relay test sent a diagnostic without a version, so the new path never ran in tests.
The diagnostic case sets b.version without locking again (the lock is already held). TestRelayPairingIsolationAndStop
now sends a versioned diagnostic and checks the status reports it; with the bug it hangs.
GitHub verify run of the relay tests. Needs a deploy to RTS (and Excellence/Confida, which run the same code since their deploy) before any extension connects there, or the relay will deadlock again.
Auto-synced from docs/ on main. Edit there, not here.