Close the live-mirror flow hand-off gaps that skipped a timed phase

Field incident (2026-07-17): a Cardio flow run driven from a locked phone
durably completed the 30-min Main Circuit ~5 minutes in, then fought the
watch until manual swipes forced agreement. Second bulletproofing pass
(BULLETPROOFING.md, "2026-07-18 — Live-run mirror & flow hand-off"):

- H4: RunFlowView (both platforms) follows the driver's cross-log
  hand-off frame (forward-only by plan order, runnable target only), and
  a remote completion mid-flow hands off via onAdvance instead of
  dismissing the run (which tore down the Live Activity and stranded the
  flow in the mirror cover).
- H5: wall-clock plausibility gate — a duration exercise never
  auto-completes before startedAt + sets × duration; the flow-terminal
  rest self-repairs to computeResume() and the Finish auto-Done holds
  for a human tap. Human Done taps stay ungated.
- M6: both bridges persist liveVersion as a UserDefaults high-water mark
  so an app relaunch can't get every subsequent frame dropped as stale.
- M7: phone list + mirror cover absorbs gain the watch's strictly-newer
  guard, so a stale cache echo can't regress the working doc.
- Diagnostics: run-flow os_log breadcrumbs (page transitions, applied
  frames, repairs, hand-offs, gate trips) on both drivers.

Open, documented: M5 (no reconciliation signal across a single-set
duration phase), M8 (watch context apply lacks per-log staleness guard),
L5 (spurious pager write-backs read as human swipes).

Workouts/Views/WorkoutLogs/ExerciseProgressView.swift

@@ -5,6 +5,7 @@
 // Copyright 2025 Rouslan Zenetl. All Rights Reserved.
 //
 
+import os
 import SwiftUI
 import UIKit
 
@@ -29,6 +30,10 @@ import UIKit
 /// workout stopwatch in big glanceable digits. A row of phase dots tracks progress:
 /// purple for work, teal for rest, with the current phase drawn as a wider dash.
 struct ExerciseProgressView: View {
+    /// Run-flow breadcrumbs (page transitions, applied frames, repairs) — the mirror's
+    /// failure modes are cross-device timing races, unattributable without a trail.
+    private static let log = Logger(subsystem: "dev.rzen.indie.Workouts", category: "run-flow")
+
     @Environment(\.dismiss) private var dismiss
     @Environment(\.verticalSizeClass) private var verticalSizeClass
     @Environment(\.modelContext) private var modelContext
@@ -486,6 +491,7 @@ struct ExerciseProgressView: View {
             guard didRestorePage else { return }
             let cause = pageChangeCause
             pageChangeCause = nil
+            Self.log.info("page \(oldPage) → \(newPage) cause=\(cause.map { "\($0)" } ?? "human", privacy: .public) log=\(logID, privacy: .public)")
             switch cause {
             case .remote:
                 // The watch already recorded and owns this transition — just follow it.
@@ -519,13 +525,24 @@ struct ExerciseProgressView: View {
         }
         .onChange(of: log?.status) { _, raw in
             // The log resolved out from under us (the run was completed or ended early on
-            // another device). Leave the live flow — staying would let the next recorded
-            // set write a resolved log back to in-progress, resurrecting it through the
-            // merge. `locallyResolved` keeps our own Done / flow hand-off from re-dismissing.
+            // another device). Staying would let the next recorded set write a resolved log
+            // back to in-progress, resurrecting it through the merge. In flow mode a remote
+            // *completion* means the driver has already handed off — follow it to the next
+            // unfinished exercise instead of falling out of the run (which would tear down
+            // the Live Activity and strand the flow in the mirror cover). Everything else
+            // (skipped, last exercise, non-flow) leaves the flow as before.
+            // `locallyResolved` keeps our own Done / flow hand-off from re-triggering this.
             guard didRestorePage, !locallyResolved,
                   let status = raw.flatMap(WorkoutStatus.init(rawValue:)),
                   status == .completed || status == .skipped else { return }
-            dismiss()
+            locallyResolved = true
+            if autoAdvance, status == .completed, let next = nextUnfinishedLogID, let onAdvance {
+                Self.log.info("remote completion of \(logID, privacy: .public) → flow hand-off to \(next, privacy: .public)")
+                onAdvance(next)
+            } else {
+                Self.log.info("remote resolve of \(logID, privacy: .public) (\(status.rawValue, privacy: .public)) → dismiss")
+                dismiss()
+            }
         }
         .onAppear {
             guard !didRestorePage else { return }
@@ -666,6 +683,7 @@ struct ExerciseProgressView: View {
         lastAppliedStart = frame.phaseStart
         if frame.setCount != setCount { setCount = frame.setCount }
         let target = page(forPhase: frame.phase, setIndex: frame.setIndex)
+        Self.log.info("apply frame v\(frame.version) \(frame.phase.rawValue, privacy: .public)/\(frame.setIndex) → page \(target) log=\(logID, privacy: .public)")
         // A followed frame is progress this screen now *knows*, so a durable echo of the
         // same transition can't re-trigger the repair jump (a remote reset re-baselines).
         knownStateIndex = frame.phase == .ready ? 0 : max(knownStateIndex, completedSets(for: target))
@@ -693,6 +711,7 @@ struct ExerciseProgressView: View {
         if log.sets > setCount { setCount = log.sets }
         let target = base + min(max(0, completed), setCount - 1) * 2
         guard target > currentPage else { return }
+        Self.log.info("durable repair: completed=\(completed) → page \(target) log=\(logID, privacy: .public)")
         clearAnchor()
         pageChangeCause = .remote
         withAnimation { currentPage = target }
@@ -704,6 +723,33 @@ struct ExerciseProgressView: View {
         pageAnchor = nil
     }
 
+    /// Wall-clock plausibility gate for *automatic* completion of a duration exercise: its
+    /// work windows alone take `sets × duration`, so an auto-fire earlier than that (minus
+    /// slack) proves the terminal page was reached erroneously — a spurious pager
+    /// write-back or a stale anchor, not a run that actually happened. Human Done taps are
+    /// never gated; rep-based exercises have no wall-clock expectation and always pass, as
+    /// does a log missing its `startedAt` stamp (nothing to judge against).
+    private var autoCompletionPlausible: Bool {
+        guard isDuration, let log, let started = log.startedAt else { return true }
+        let minimum = Double(workDurationSeconds * setCount) - 2
+        return Date().timeIntervalSince(started) >= minimum
+    }
+
+    /// The flow-terminal rest fired before the exercise could have run (see
+    /// `autoCompletionPlausible`) — jump back to where the durable timestamps say the run
+    /// actually is instead of durably completing a phase that never happened.
+    private func repairEarlyTerminal() {
+        let resume = computeResume()
+        Self.log.warning("early terminal auto-fire blocked for \(logID, privacy: .public); repairing to page \(resume.page)")
+        guard currentPage != resume.page else {
+            pageAnchor = resume.anchor
+            return
+        }
+        pageAnchor = resume.anchor
+        pageChangeCause = .remote
+        withAnimation { currentPage = resume.page }
+    }
+
     /// Inverse of `liveSnapshot`'s page→frame mapping: a frame's phase/set → page index.
     private func page(forPhase phase: LiveRunPhase, setIndex: Int) -> Int {
         let set = min(max(0, setIndex), max(0, setCount - 1))
@@ -786,6 +832,9 @@ struct ExerciseProgressView: View {
                         onActivate: announceComingUp,
                         onCountdownBeat: announceCountdownBeat
                     ) { _ in
+                        // An auto-fire before the exercise could possibly have run proves
+                        // this page was reached erroneously — repair, don't complete.
+                        guard autoCompletionPlausible else { repairEarlyTerminal(); return }
                         completeExercise()
                         // Re-resolve at fire time — the next exercise may have been
                         // finished elsewhere while we rested. None left ⇒ end the run.
@@ -805,7 +854,8 @@ struct ExerciseProgressView: View {
                         isActive: isActive,
                         onDone: { completeExercise(); dismiss() },
                         onOneMore: addSet,
-                        anchorEnd: anchorEnd
+                        anchorEnd: anchorEnd,
+                        autoFireAllowed: { autoCompletionPlausible }
                     )
                     .overlay(alignment: .bottom) { adjustPill }
                 }
@@ -1777,6 +1827,11 @@ private struct FinishPhaseView: View {
     /// sender's wall clock instead of local `now + countdown`, so both devices fire together.
     var anchorEnd: Date? = nil
 
+    /// Gates the *automatic* Done only (the tap always works): when false, the countdown
+    /// holds at zero awaiting a human — the host's wall-clock plausibility check says the
+    /// exercise can't genuinely be finished yet (see `autoCompletionPlausible`).
+    var autoFireAllowed: () -> Bool = { true }
+
     @AppStorage("doneCountdownSeconds") private var doneCountdownSeconds: Int = 5
 
     /// Wall-clock deadline for the auto-Done. `remaining` is what the Done button shows.
@@ -1824,7 +1879,7 @@ private struct FinishPhaseView: View {
         if max(0, r) != remaining {
             withAnimation(.snappy(duration: 0.25)) { remaining = max(0, r) }
         }
-        if r <= 0 { fire() }
+        if r <= 0, autoFireAllowed() { fire() }
     }
 
     private func fire() {