feat(workout): recover common session failures

Make the workout exemplar recover cleanly from invalid edits, accidental double-advance, replay parse failures, and denied or timed-out host export results while keeping local events as truth.

req: examples/001

req: local/001

req: local/003

req: local/004

req: host/002

req: host/005

examples/workout/src/lib.rs

@@ -388,12 +388,23 @@ impl WorkoutState {
             .join("\n")
     }
 
-    fn replay_export(&mut self, export: &str) -> usize {
+    fn replay_export(&mut self, export: &str) -> Result<usize, String> {
         // req: local/001 req: local/003 req: local/004
-        let events = export
+        let lines = export
             .lines()
-            .filter_map(WorkoutEvent::from_export_line)
+            .filter(|line| !line.trim().is_empty())
             .collect::<Vec<_>>();
+        if lines.is_empty() {
+            return Err("nothing to replay yet; complete a set first".into());
+        }
+
+        let mut events = Vec::with_capacity(lines.len());
+        for (index, line) in lines.iter().enumerate() {
+            let event = WorkoutEvent::from_export_line(line)
+                .ok_or_else(|| format!("line {} is not a workout event", index + 1))?;
+            events.push(event);
+        }
+
         let mut replayed = WorkoutState::demo();
         for event in &events {
             replayed.events.push(event.clone());
@@ -404,7 +415,26 @@ impl WorkoutState {
             events.len()
         );
         *self = replayed;
-        events.len()
+        Ok(events.len())
+    }
+
+    fn recovery_text(&self) -> String {
+        match self.activity.front() {
+            Some(last) if last.starts_with("started ") => {
+                format!("Last action: {last}. If that was a double tap, Undo returns to rest.")
+            }
+            Some(last) if last.starts_with("changed ") => {
+                format!("Last action: {last}. Undo restores the previous plan.")
+            }
+            Some(last) if last.starts_with("skipped ") => {
+                format!("Last action: {last}. Undo restores the skipped exercise.")
+            }
+            Some(last) if last.starts_with("undid ") => {
+                format!("Recovery complete: {last}. Continue from the restored next action.")
+            }
+            Some(last) => format!("Last action: {last}. Undo is available."),
+            None => "Undo appears here after your first session event.".into(),
+        }
     }
 }
 
@@ -575,11 +605,7 @@ pub fn view(state: &WorkoutState) -> Workout {
         primary_action: state.projection.primary_action.clone(),
         status: state.projection.progress.clone(),
         progress: state.projection.progress.clone(),
-        recovery_status: state
-            .activity
-            .front()
-            .map(|last| format!("Last action: {last}. Undo is available."))
-            .unwrap_or_else(|| "Undo appears here after your first session event.".into()),
+        recovery_status: state.recovery_text(),
         event_log: state.event_log_text(),
         export_payload: if export.is_empty() {
             "Complete a set to create a replayable export.".into()
@@ -597,7 +623,7 @@ pub fn render(state: &WorkoutState) -> Html {
 #[derive(Clone, Debug)]
 #[hemx::form("change_weight")]
 pub struct ChangeWeightInput {
-    kg: f32,
+    kg: String,
 }
 
 #[derive(Clone, Debug)]
@@ -617,6 +643,9 @@ pub fn interactions(state: AppState) -> impl hemx_axum::DispatchRegistry {
         .on_state(ui::workout::replay_export, replay_export)
         .on_state(ui::workout::export_log, export_log)
         .on_state(ui::workout::record_share_result, record_share_result)
+        .on_state(ui::workout::record_share_denied, record_share_denied)
+        .on_state(ui::workout::record_host_timeout, record_host_timeout)
+        .on_state(ui::workout::replay_broken_export, replay_broken_export)
         .on_state(ui::workout::request_native_haptic, request_native_haptic)
         .on_state(
             ui::workout::record_native_haptic_ack,
@@ -698,7 +727,22 @@ pub fn undo_last_action(app: AppState) -> impl IntoEffect {
 }
 
 pub fn change_weight_form(app: AppState, Form(input): Form<ChangeWeightInput>) -> impl IntoEffect {
-    change_weight(app, input.kg)
+    app.update(|state| match input.kg.trim().parse::<f32>() {
+        Ok(kg) if kg.is_finite() && kg >= 0.0 => {
+            let event = state.accept(WorkoutCommand::ChangeWeight { kg });
+            effects(
+                state,
+                event.map_or_else(
+                    || "Enter a valid weight for the current or next exercise.".into(),
+                    |event| event.summary(),
+                ),
+            )
+        }
+        _ => effects(
+            state,
+            String::from("Enter a valid non-negative weight; your session is unchanged."),
+        ),
+    })
 }
 
 pub fn record_note_form(app: AppState, Form(input): Form<RecordNoteInput>) -> impl IntoEffect {
@@ -722,8 +766,26 @@ pub fn replay_export(app: AppState) -> impl IntoEffect {
     app.update(|state| {
         // req: local/001 req: local/003 req: local/004
         let export = state.export_event_log();
-        let count = state.replay_export(&export);
-        effects(state, format!("Replayed {count} exported workout events"))
+        match state.replay_export(&export) {
+            Ok(count) => effects(state, format!("Replayed {count} exported workout events")),
+            Err(error) => effects(
+                state,
+                format!("Replay failed: {error}. Current session is unchanged."),
+            ),
+        }
+    })
+}
+
+pub fn replay_broken_export(app: AppState) -> impl IntoEffect {
+    app.update(|state| {
+        // req: local/001 req: local/003 req: local/004
+        match state.replay_export("not-a-workout-export") {
+            Ok(count) => effects(state, format!("Replayed {count} exported workout events")),
+            Err(error) => effects(
+                state,
+                format!("Replay failed: {error}. Current session is unchanged."),
+            ),
+        }
     })
 }
 
@@ -764,6 +826,33 @@ pub fn record_share_result(app: AppState) -> impl IntoEffect {
     })
 }
 
+pub fn record_share_denied(app: AppState) -> impl IntoEffect {
+    app.update(|state| {
+        // req: host/002 req: host/005 req: local/003
+        apply_host_event(
+            state,
+            HostEvent::PermissionDenied {
+                capability: Capability::Share,
+            },
+        );
+        effects(state, "Share permission denial returned through app code")
+    })
+}
+
+pub fn record_host_timeout(app: AppState) -> impl IntoEffect {
+    app.update(|state| {
+        // req: host/002 req: host/005 req: local/003
+        apply_host_event(
+            state,
+            HostEvent::Failed {
+                id: Some(HostCallId::new("workout-export")),
+                message: "share timed out".into(),
+            },
+        );
+        effects(state, "Host timeout returned through app code")
+    })
+}
+
 pub fn request_native_haptic(app: AppState) -> impl IntoEffect {
     app.update(|state| {
         // req: host/001 req: host/004
@@ -810,7 +899,18 @@ fn apply_host_event(state: &mut WorkoutState, event: HostEvent) {
         HostEvent::ShareCompleted {
             completed: false, ..
         } => {
-            state.host_status = "Share cancelled; local event log unchanged.".into();
+            state.host_status =
+                "Share cancelled; local event log unchanged. Try Share export when ready.".into();
+        }
+        HostEvent::PermissionDenied { capability } if capability == Capability::Share => {
+            state.host_status =
+                "Share permission denied. Local export text is still ready; try again or copy it."
+                    .into();
+        }
+        HostEvent::Failed { message, .. } => {
+            state.host_status = format!(
+                "Host unavailable: {message}. Keep the local export below and try Share export again."
+            );
         }
         HostEvent::Acknowledged { id } if id.0 == "workout-set-haptic" => {
             state.host_status =
@@ -912,6 +1012,31 @@ mod tests {
         );
     }
 
+    #[test]
+    fn invalid_weight_and_replay_failure_keep_session_recoverable() {
+        // req: examples/001 req: local/001 req: local/003 req: local/004
+        let app = AppState::demo();
+        run(|()| complete_set(app.clone()), ());
+
+        let invalid = run(
+            |input| change_weight_form(app.clone(), Form(input)),
+            ChangeWeightInput { kg: "oops".into() },
+        );
+        assert!(contains_payload_text(&invalid, "valid non-negative weight"));
+        assert_eq!(
+            app.with_workout(|state| (state.events.len(), state.projection.phase.clone())),
+            (1, WorkoutPhase::Resting)
+        );
+
+        let replay = run(|()| replay_broken_export(app.clone()), ());
+        assert!(contains_payload_text(&replay, "Replay failed: line 1"));
+        assert!(contains_payload_text(
+            &replay,
+            "Current session is unchanged"
+        ));
+        assert_eq!(app.with_workout(|state| state.events.len()), 1);
+    }
+
     #[test]
     fn export_payload_replays_into_projection_before_ui_effects() {
         // req: local/001 req: local/003 req: local/004
@@ -964,6 +1089,29 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn host_failure_results_keep_local_export_recoverable() {
+        // req: host/002 req: host/005 req: local/003
+        let app = AppState::demo();
+        run(|()| complete_set(app.clone()), ());
+
+        let denied = run(|()| record_share_denied(app.clone()), ());
+        assert!(contains_payload_text(&denied, "Share permission denial"));
+        assert!(contains_payload_text(
+            &denied,
+            "Local export text is still ready"
+        ));
+        assert!(!app.with_workout(|state| state.projection.exported));
+
+        let timeout = run(|()| record_host_timeout(app.clone()), ());
+        assert!(contains_payload_text(&timeout, "Host timeout"));
+        assert!(contains_payload_text(
+            &timeout,
+            "Keep the local export below"
+        ));
+        assert_eq!(app.with_workout(|state| state.events.len()), 1);
+    }
+
     #[test]
     fn native_shell_haptic_result_returns_through_app_code() {
         // req: host/001 req: host/002 req: host/005
@@ -999,6 +1147,8 @@ mod tests {
         assert!(html.contains("Undo last action"));
         assert!(html.contains("Share export"));
         assert!(html.contains("Host proof panel"));
+        assert!(html.contains("Simulate share denied"));
+        assert!(html.contains("Simulate replay failure"));
         assert!(!html.contains(&format!("<{}", "script")));
         assert!(!html.contains("querySelector"));
     }