fix: make auto-reconnect watcher state main-only to close a data race#38
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The watcher's state (reconnectWatchlist / reconnectInFlight / intentionalReleases / reconnectTimer) is documented main-only, but the peripheral handoff reaches `unregisterFromPC` on the outgoing-connection queue: `performHandoffToPeer` runs inside an `OutgoingConnection` completion, which fires on `com.magicswitch.outgoing`, not main. So `disarmReconnect` / `noteIntentionalRelease` mutated those Swift collections (and cancelled the main-queue timer) off-main, racing `reconnectTick` and `handlePeripheralDisconnected` — a data race on non-thread-safe collections that can lose the intentional-release flag (causing the watcher to fight a handoff) or corrupt/trap. Hop `armReconnect` / `disarmReconnect` / `noteIntentionalRelease` to main, matching the existing `setConnectionState` pattern; this also guarantees the flag is set before the disconnect handler reads it. Also fixed alongside it: - Clear the intentional-release flag when `closeConnection()` fails, so a release that never happened can't permanently suppress a later genuine drop's auto-reconnect. - Register a disconnect observer when a probe finds the device already reconnected on its own, so its next drop re-arms the watcher (the genuine drop had unregistered the old observer). - Skip the pre-sleep IOBluetooth scan when neither `releaseOnSleep` nor `autoReconnect` needs it, rather than block the held sleep transition to build a `connectedBeforeSleep` snapshot nothing will read.
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What & why
The auto-reconnect watcher's state (
reconnectWatchlist,reconnectInFlight,intentionalReleases,reconnectTimer) is documented main-only, but the peripheral handoff reachesunregisterFromPCon the outgoing-connection queue:performHandoffToPeerruns inside anOutgoingConnectioncompletion, which fires oncom.magicswitch.outgoing, not main. SodisarmReconnect/noteIntentionalReleasemutated those non-thread-safe Swift collections (and cancelled the main-queue timer) off-main, racingreconnectTickandhandlePeripheralDisconnected.This is a data race on the primary switch path. Beyond the collection corruption/trap risk, it can drop the intentional-release flag — so the watcher fights a just-completed handoff and tries to reclaim a peripheral that was handed to the peer.
Changes
armReconnect/disarmReconnect/noteIntentionalReleasenow hop to main (mirrors the existingsetConnectionStatepattern). This also guarantees the intentional-release flag is set beforehandlePeripheralDisconnectedreads it.closeConnection()fails — no disconnect follows to consume it, so otherwise it would permanently suppress a later genuine drop's auto-reconnect.releaseOnSleepnorautoReconnectneeds it, instead of blocking the held sleep transition to build an unusedconnectedBeforeSleepsnapshot.Testing
xcodebuild -configuration Debug build CODE_SIGNING_ALLOWED=NO-> BUILD SUCCEEDEDswift formatcleanNot in scope (follow-ups)
Silent give-up notification after the 1h window; bounding
bluetoothQueue.syncagainst an in-flight pair at sleep; distinguishingOP_FAILEDfrom transport errors inHOLDS_ONE; multi-Mac (>2) reclaim usingnetworkDevices.first.