rzen
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Two stale-UI traps in the run flow (BULLETPROOFING.md M2, M3): A log resolved remotely (completed or skipped on the other device) left the open exercise screen live - its next recorded set wrote the log back to in-progress, resurrecting it through the per-log merge. Both platforms' ExerciseProgressView now observe the log's status and dismiss on a remote terminal flip (a locallyResolved flag exempts the screen's own Done / flow hand-off). The watch also gains the phone's startsSkipped terminal page, so opening a skipped exercise shows a static badge instead of a live flow. The live-mirror cover ran the flow engine with no onAdvance host, so an auto-advance split's terminal between-exercise rest completed the exercise then froze at 0:00. With no hand-off host it now dismisses instead; the driver's next-exercise frame re-presents the cover. Claude-Session: https://claude.ai/code/session_01PVNBVKp5bcq52X722uMjwT
126 lines
14 KiB
Markdown
126 lines
14 KiB
Markdown
# Bulletproofing the Watch/Phone UX — Findings
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An adversarial gap analysis of the iPhone ↔ Apple Watch communication layer, aimed at making the cross-device workout UX bulletproof. Architecture reference: `DEVICE-COMMUNICATION.md` (transports T1–T4, exchanges P1–P9 / W1–W4). Analysis date: 2026-07-09.
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Findings are ranked by user impact. Each carries code evidence, the concrete failure scenario, and a fix direction. Statuses: **open** / **fixed** (update in place as items land).
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---
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## What's already solid (verified)
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Re-verified against code, not just prior docs — these need no work and should not be re-litigated:
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- **Per-log merge** (`WorkoutMergePlanner`) — unordered T3/T4 delivery and concurrent edits to different exercises commute; phone-authored `deletedLogIDs` tombstones disambiguate absent logs.
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- **Tombstone veto** (`SyncEngine.ingestFromWatch`) — a stale watch push can never resurrect a deleted workout; authoritative state is re-pushed instead.
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- **Latest-wins context + authoritative prune** (`WatchCacheApplier`) — "absent ⇒ no longer active" reliably ends the watch session on phone-side delete/discard, and a nil-decode can never wipe real rows.
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- **Launch-race guard** (`SessionEndPlanner.decide`: `!previouslyActiveIDs.isEmpty`) — a freshly launched session is never killed just because its run document hasn't synced yet (empty-baseline case).
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- **Timer hardening** — countdown/haptic logic is wall-clock anchored on both platforms; sleep and Always-On drift self-correct without double-firing.
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- **Pop-on-prune** (`ActiveWorkoutGateView.popIfNavigatedRunUnavailable`) — deletion/discard of the navigated run, or a phone edit lock, pops the watch back to the gate.
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---
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## HIGH — the session lifecycle has a single point of failure
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### H1 — The `HKWorkoutSession` can only ever be born via the T1 one-shot · **fixed**
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> **Fix (2026-07-09):** the coordinator now self-starts a session on any reconcile that finds an active run with none running (`SessionEndPlanner.shouldStart` / `runToStart`; activity type resolved from the run's split), and `WorkoutSessionManager.recover()` re-adopts a crash/reboot-orphaned session at launch (`recoverActiveWorkoutSession`). T1 is now a fast-launch optimization, not the sole session source.
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`WorkoutSessionManager.start(with:)` has exactly one caller: `WatchAppDelegate.handle(_:)` (`WatchAppDelegate.swift:31`), i.e. the phone's `startWatchApp(toHandle:)` handoff. That handoff is best-effort `try?` with **no retry** (`WorkoutLauncher.swift:37-40`). There is no `HKHealthStore.recoverActiveWorkoutSession` anywhere, no `WKExtendedRuntimeSession`, and nothing gates run-flow entry on `sessionManager.isRunning`.
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Failure scenarios (all real):
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1. **T1 fails silently** (watch briefly unreachable, Bluetooth blip, watch on charger at start) → the entire workout runs sessionless: no HR/energy, no Health save, no wrist-raise resurfacing, and the watch app **fully suspends** wrist-down — rest haptics and done-countdowns don't fire until the user manually reopens the app. The user gets no hint anything is wrong.
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2. **Watch app crash or reboot mid-run** → watchOS expects the app to reclaim the live session via `recoverActiveWorkoutSession`; unimplemented, so the session is orphaned — metrics lost, zombie session may linger.
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3. **User manually opens an active run on the watch** (run arrived via T2; T1 never fired for this device state) → same sessionless degradation.
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**Fix direction:** make the watch own its session lifecycle. Self-start a session when entering (or reconciling into) an active run with `isRunning == false`; implement session recovery at launch. T1 then becomes a fast-launch optimization rather than the sole source of sessions. This also absorbs most of H2 and much of the M-tier degradation.
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### H2 — "End Current & Start New" swallows the new run's session · **fixed**
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> **Fix (2026-07-09):** absorbed by H1's self-start (a swallowed T1 heals at the next reconcile), plus a session-age rule in the planner: a `.finish` decided for a session younger than `minimumFinishAge` (30 s) demotes to `.discard`, so the transient "old run completed, new run not yet pushed" context can no longer save a junk seconds-long HKWorkout attributed to the old run — the session is discarded and self-start brings it back when the new run's push lands.
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`endActiveThenStart` (`WorkoutLogsView.swift:271-281`) runs the end-saves in a `Task` but calls `start(with:)` synchronously — so **T1 goes out while the old run's session is still running on the watch**. `handle(_:)` → `start(with:)` hits the `session == nil` idempotency guard (`WorkoutSessionManager.swift:61`) and is **silently dropped**. Moments later the "A completed" push arrives and the coordinator finishes A's session — leaving run B sessionless (all of H1's fallout). The one-shot was consumed while blocked; nothing replays it.
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Timing variant: if B's session *does* start (old one already ended) but the transient "A completed, B not yet present" push applies next, `SessionEndPlanner.decide` sees `isRunning`, empty active set, non-empty baseline `{A}` → `.finish(A)` — **ending B's seconds-old session and attributing its metrics to A**. The empty-baseline launch guard doesn't cover a *non-empty stale* baseline.
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**Fix direction:** on the watch, when `handle(_:)` arrives while a session is running, stash the configuration and start it immediately after the current session finishes; and/or a short grace window after `session.startActivity(...)` during which `decide` refuses `.finish`/`.discard`. H1's self-start largely absorbs this too.
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### H3 — A system-ended session silently drops the Health save · **fixed**
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> **Fix (2026-07-09):** `salvageSystemEndedSession` — a system-driven `.ended`/`.stopped` now ends collection and finishes the builder's workout (saving the `HKWorkout` to Health) instead of clearing everything. Residual: the salvaged workout isn't linked to a run document (`healthKitWorkoutUUID` stays nil) and no metrics are forwarded — the runs are still active, so there's no completed run to attach them to.
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`workoutSession(_:didChangeTo:)` for `.ended`/`.stopped` only calls `clear()` (`WorkoutSessionManager.swift:199-202`) — no `endCollection`/`finishWorkout`, no metrics capture, no forward to the phone. `PLAN-watch-session-end.md` lists this as a known residual. Rare (OS reclaim under resource pressure), but it is a "my workout never made it to Health" support report waiting to happen.
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**Fix direction:** on a system-driven `.ended`, attempt `finishAndSave()` (or at minimum salvage the builder's collected data) before clearing, and forward whatever metrics exist.
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---
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## MEDIUM — stranding and stale-UI traps
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### M1 — Edit locks have no expiry and outlive their editor · **fixed** (expiry) / open (split-lock scope)
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> **Fix (2026-07-09):** `PhoneConnectivityBridge.setLocksSuspended` — the scene-phase hook publishes the locks as *cleared* while the app is backgrounded (without forgetting them locally) and re-asserts them on return to foreground, so a pocketed or force-quit phone can no longer park the watch's run indefinitely. The split-lock *scope* (viewing `SplitDetailView` parks runs) was deliberately left as-is: that screen hosts inline edits (reorder, swipe-delete, add), so narrowing the lock to its sheets would reopen the clobber risk it exists to prevent.
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`editingWorkoutID` / `editingSplitID` ride in the latest-wins context and are cleared only by `onDisappear` (`ExerciseView.swift:78`, `SplitDetailView.swift:55`). Force-quit the phone with an editor open — or just leave it open in a pocket — and the **last-pushed context says "editing" indefinitely**; the watch parks the run ("Editing on iPhone…") until the phone app next runs `pushAll`. Compounding it, `SplitDetailView` is a mostly-*read* screen: merely **viewing** a split in Settings parks any active watch run sourced from it (`SplitDetailView.swift:54`).
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**Fix direction:** clear the locks on phone `scenePhase` → background/inactive; scope the split lock to the actual edit sheets rather than the detail screen.
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### M2 — Remote completion doesn't pop the watch's open exercise screen · **fixed**
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> **Fix (2026-07-09):** both platforms' `ExerciseProgressView` now observe `log?.status` and dismiss when the log resolves to `.completed`/`.skipped` remotely (a `locallyResolved` flag keeps their own Done / flow hand-off from re-dismissing) — a stale open flow can no longer write a resolved log back to in-progress. The watch also gained the phone's `startsSkipped` terminal page (`SkippedPhaseView`), so opening a skipped exercise shows a static badge instead of a live, resurrectable flow. Gate-level popping was deliberately not added: with the screen-level dismissal the resurrection path is closed, and reviewing a just-completed run's list is legitimate.
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`popIfNavigatedRunUnavailable` pops on prune and on lock — but a run flipping to `.completed`/`.skipped` remotely **stays in the cache** (recently-completed runs are still pushed for ~24 h), so no pop fires. `repairFromDurable`'s safety net is gated on `status == .inProgress`, going silent exactly when needed. And the watch's `ExerciseProgressView` lacks the phone's `.skipped` handling, so a user sitting on a stale open exercise can keep ticking and write it back to a **non-terminal status** — resurrecting a skip through the per-log merge, since their edit is "newer".
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**Fix direction:** pop (or overlay a terminal state) when the navigated run leaves the active set, not only when it leaves the cache; port the phone's `.skipped` terminal handling to the watch's progress view.
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### M3 — Follower mirror cover freezes in auto-advance splits · **fixed** (freeze) / open (mid-set staleness)
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> **Fix (2026-07-09):** the terminal between-exercise rest now falls back to `dismiss()` when there's no `onAdvance` host (the live-mirror cover on both platforms) — the exercise still completes durably, the cover closes instead of freezing at 0:00, and the driver's next-exercise frame re-presents it. Residual: a cover sitting on a *count-up work page* when the driver dies still has no staleness timeout — acceptable because that surface is a take-over driver by design and dismissible by hand.
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The live-mirror cover (`LiveRunCoverView`, both platforms) is not a passive display — it runs the same local phase engine as a real driver, seeded from the last frame's anchors, and keeps advancing if the driver goes silent. Single-exercise runs self-heal (Finish auto-Done dismisses). But the cover is wired with `onAdvance: nil`, so in a flow-mode (auto-advance) split, when its local chain reaches the terminal between-exercise rest it completes the exercise (durable data stays correct) then **freezes at a 0:00 countdown** — the exercise hand-off exists only in `RunFlowView`, which the cover doesn't use. Related: if the driver dies without `sendLiveEnded`, the follower has **no staleness timeout** at all.
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**Fix direction:** give the cover a terminal-rest hand-off (advance or dismiss), and add a staleness timeout that dismisses the cover when no frame arrives past `phaseEnd` + grace.
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### M4 — `updateApplicationContext` size ceiling; failure is log-only · **fixed**
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> **Fix (2026-07-09):** `pushAll` now degrades on failure instead of freezing the watch: a failed push retries with the recently-completed tail dropped (display-only on the watch — active runs, splits, settings, and locks all still go through), logged as a warning; only a failure of the slim push too remains an error. Deeper tiers (trimming embedded logs) weren't needed — active runs are a handful by construction.
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`pushAll` sends *all* splits plus all active and ≤25 recent-completed runs with their full logs. A heavy user (many splits × many exercises; long runs with `setEntries`) can plausibly exceed WatchConnectivity's ~65 KB context limit. On throw, the error is logged (`PhoneConnectivityBridge.swift:121-124`) and **the watch silently never hears about anything again** — functionally the same total-freeze as the schema-mismatch trap, but reachable in production.
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**Fix direction:** on payload-too-large, degrade in tiers (drop completed runs, then trim embedded logs to what the watch renders) and re-push; surface the condition in Diagnostics.
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---
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## LOW
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### L1 — Nondeterministic metrics attribution with parallel runs · **fixed**
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`SessionEndPlanner.decide` picked the completed survivor by iterating `previouslyActiveIDs` — a `Set`, so iteration order was undefined. With two parallel runs finishing together, the `HKWorkout`'s metrics attached to an arbitrary one.
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> **Fix (2026-07-09):** `decide` now picks the most recently started completed survivor, ties broken by id (landed with the H-tier session-lifecycle commit; pinned by `parallelCompletions_pickMostRecentlyStarted`).
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### L2 — `requestSync` failures vanish · open
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`sendMessage(WCPayload.requestSyncMessage(), replyHandler: nil, errorHandler: nil)` (`WatchConnectivityBridge.swift`) — a failed pull is dropped with no retry. Low because P8 (activation/reachability edges) and the durable T2 slot cover the common cases.
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### L3 — Decode-failure freeze is silent on the watch · open
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The schema-mismatch trap (see `DEVICE-COMMUNICATION.md` §6) is dev-only today, but the watch could surface "can't read phone data — update both apps" instead of freezing silently; it already tracks `lastSyncDate` and logs the decode failure.
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### L4 — Possible log-progress rollback from a late follower write · open · needs device testing
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Both the driver and a follower cover persist auto-advance progress via whole-log newest-`updatedAt`-wins merge (not a monotonic max on progress). A follower resuming late from suspend could in theory regress a log if its delayed write's timestamp outranks the driver's more-advanced state before the durable echo catches it up. Unconfirmed on device.
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---
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## Recommended order
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The common theme of every HIGH: **the watch doesn't own its session lifecycle — it's a passive recipient of a fire-and-forget launch.** Fix in this order:
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1. **H1** — watch self-starts + recovers its session (one coherent change in `WorkoutSessionManager` / coordinator / run-flow entry; collapses most of H2, part of M-tier).
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2. **H2** — pending-config replay and/or post-start grace window in `SessionEndPlanner`.
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3. **H3** — salvage the Health save on system-ended sessions.
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4. **M1** — lock expiry on scene background; narrow the split lock.
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5. **M4** — tiered payload degradation + Diagnostics surfacing.
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6. Then M2, M3, and the L-tier as opportunity allows.
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