harness-tui + engine: jobs pane, subtask drill-in, reminders (M4)

TUI: Ctrl+J (or /jobs) opens a jobs pane listing the current session's board —
alias, agent, state, objective, files read — populated on load and kept live via
JobUpdated events; Enter drills into a subtask's child session. Snapshot test added.

Engine: optional orchestration reminders (off by default) injected as synthetic,
non-persisted turn-start blocks and, after a file tool runs, an after-file-tool
block on the following turn. Processor reports file-tool usage via StepOutcome.

This completes M4.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/harness-tui/src/input.rs

@@ -23,6 +23,10 @@ pub enum InputAction {
     SessionPickerUp,
     SessionPickerDown,
     SessionPickerSelect,
+    OpenJobs,
+    JobsUp,
+    JobsDown,
+    JobsDrillIn,
 }
 
 /// Translate a crossterm event into an action and/or mutate `state` directly.
@@ -49,10 +53,21 @@ fn handle_key(key: KeyEvent, state: &mut AppState) -> InputAction {
     match &state.modal {
         ModalState::Permission { .. } => handle_permission_key(key, state),
         ModalState::SessionPicker { .. } => handle_session_picker_key(key, state),
+        ModalState::JobsPane { .. } => handle_jobs_pane_key(key, state),
         ModalState::None => handle_normal_key(key, state),
     }
 }
 
+fn handle_jobs_pane_key(key: KeyEvent, _state: &mut AppState) -> InputAction {
+    match key.code {
+        KeyCode::Up => InputAction::JobsUp,
+        KeyCode::Down => InputAction::JobsDown,
+        KeyCode::Enter => InputAction::JobsDrillIn,
+        KeyCode::Esc => InputAction::CloseModal,
+        _ => InputAction::None,
+    }
+}
+
 fn handle_permission_key(key: KeyEvent, _state: &mut AppState) -> InputAction {
     match key.code {
         KeyCode::Char('y') | KeyCode::Char('Y') => {
@@ -119,6 +134,7 @@ fn handle_normal_key(key: KeyEvent, state: &mut AppState) -> InputAction {
             }
         }
         KeyCode::Char('s') if ctrl => InputAction::LoadSessions,
+        KeyCode::Char('j') if ctrl => InputAction::OpenJobs,
         KeyCode::Up => {
             let (row, _) = state.input.cursor();
             if row == 0 {
@@ -158,6 +174,7 @@ fn parse_slash_command(text: &str) -> Option<InputAction> {
         "/model" if !rest.is_empty() => Some(InputAction::SetModel(rest)),
         "/agent" if !rest.is_empty() => Some(InputAction::SetAgent(rest)),
         "/sessions" => Some(InputAction::LoadSessions),
+        "/jobs" => Some(InputAction::OpenJobs),
         "/quit" => Some(InputAction::Quit),
         _ => None,
     }
@@ -235,6 +252,45 @@ pub async fn apply_action(action: InputAction, state: &mut AppState, engine: &En
                 }
             }
         }
+        InputAction::OpenJobs => {
+            if let Some(session_id) = state.session_id.clone() {
+                match engine.jobs(session_id).await {
+                    Ok(jobs) => {
+                        state.set_jobs(jobs);
+                        state.open_jobs_pane();
+                    }
+                    Err(e) => tracing::error!(error = %e, "failed to load jobs"),
+                }
+            }
+        }
+        InputAction::JobsUp => {
+            if let ModalState::JobsPane { selected } = &mut state.modal {
+                *selected = selected.saturating_sub(1);
+            }
+            state.dirty = true;
+        }
+        InputAction::JobsDown => {
+            let job_count = state.jobs.len();
+            if let ModalState::JobsPane { selected } = &mut state.modal {
+                if *selected + 1 < job_count {
+                    *selected += 1;
+                }
+            }
+            state.dirty = true;
+        }
+        InputAction::JobsDrillIn => {
+            if let Some(child) = state.selected_job_child() {
+                match engine.get_session(child).await {
+                    Ok(Some(session)) => {
+                        if let Err(e) = modal::select_session(state, engine, session).await {
+                            tracing::error!(error = %e, "failed to open subtask session");
+                        }
+                    }
+                    Ok(None) => tracing::warn!("subtask session no longer exists"),
+                    Err(e) => tracing::error!(error = %e, "failed to load subtask session"),
+                }
+            }
+        }
         InputAction::None => {}
     }
 }