[HIGH] Data race: Runner.drivers and Runner.inputs maps unprotected + input router goroutine lifecycle

[physercoe]

Summary

Two concurrency issues in the host-runner:

1. Data race on Runner.drivers and Runner.inputs maps

Runner.drivers and Runner.inputs maps are accessed from two goroutines without synchronization:

• The main loop (launchOne(), stopDriver())
• The A2A tunnel goroutine (handleHostExit via host_verbs.go:90-96)

No mutex protects these maps. Under concurrent stop+exit, this is a real data race.

2. input_router.go fire-and-forget goroutines

input_router.go:239-257 (tick() method) launches a goroutine per event dispatch with no lifecycle tracking:

• No wg.Done() — Detach() returns without waiting for in-flight dispatches
• If driver.Input() blocks (ACP session/prompt can take up to 120s), the goroutine outlives Detach
• No mechanism to cancel in-flight dispatches on stop

3. StdioDriver/ACPDriver readLoop goroutine leak risk

readLoop() does not select on ctx.Done(). It relies on scanner EOF when the pipe closes. If Closer is nil or the pipe doesn't close, wg.Wait() in Stop() hangs indefinitely.

[physercoe]

All three sub-items resolved.

• [HIGH] Data race: Runner.drivers and Runner.inputs maps unprotected + input router goroutine lifecycle #77.1 — the data race (HIGH) → fixed in fix(hostrunner): guard drivers/gateways maps against A2A-goroutine data race (#77.1) #276 (Runner.agentsMu guards drivers+gateways; inputs is a single *InputRouter with its own mu). Regression test runner_drivers_race_test.go.
• [HIGH] Data race: Runner.drivers and Runner.inputs maps unprotected + input router goroutine lifecycle #77.2 — input-router fire-and-forget dispatch → fixed in fix(hostrunner): bound teardown waits so a wedged child can't hang stop (#77.2/#77.3) #298. Per-loop WaitGroup + bounded drain in run() before close(done). Bounded on purpose: a dispatch wedged in a ctx-ignoring driver.Input only unblocks at the driver's Stop(), which stopDriver calls after Detach — an unbounded wait would deadlock; the straggler is reaped by that Stop().
• [HIGH] Data race: Runner.drivers and Runner.inputs maps unprotected + input router goroutine lifecycle #77.3 — readLoop has no ctx.Done() → fixed in fix(hostrunner): bound teardown waits so a wedged child can't hang stop (#77.2/#77.3) #298. StdioDriver/ACPDriver Stop() now bound wg.Wait() (driverStopDrainTimeout + warn) so a nil/ineffective Closer can't hang teardown.

Shared waitTimeout helper; tests -race-clean (the dispatch-drain test verified to fail without the fix). Closing.