feat: give the TUI model a revision signal and picker state

The app layer repaints on state change, so the store has to be able to
say that something changed: `revision` is bumped by every mutating
method, and the repaint test compares it against the last painted frame.
Without it an idle dashboard would either redraw on a timer or go stale.

Three additions come with it, all optional so nothing existing changes
shape: `TuiSessionRow.muxName` (the unified list carries no mux name, so
the app fills it in from the local tmux enumeration and a row without one
cannot be attached), a `new-session` UI mode, and `TuiPickerState`, the
one-column chooser behind `n`.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/tui/tui-model.ts

@@ -26,6 +26,7 @@ import type {
   TuiGroupKey,
   TuiHeaderInfo,
   TuiMessage,
+  TuiPickerState,
   TuiPreview,
   TuiRenderModel,
   TuiRow,
@@ -200,6 +201,7 @@ export function mergeSessionRow(existing: TuiSessionRow, incoming: TuiSessionRow
 export class TuiModelStore implements TuiRenderModel {
   private sessionsById = new Map<string, TuiSessionRow>();
   private approvalsBySession = new Map<string, ApprovalItem>();
+  private _revision = 0;
 
   selectedId: string | null = null;
   connection: TuiConnectionStatus = 'connected';
@@ -208,12 +210,27 @@ export class TuiModelStore implements TuiRenderModel {
   preview: TuiPreview | null = null;
   message: TuiMessage | null = null;
   confirm: TuiConfirmState | null = null;
+  picker: TuiPickerState | null = null;
   recentLimit: number;
 
   constructor(options: GroupOptions = {}) {
     this.recentLimit = Math.max(0, Math.floor(options.recentLimit ?? DEFAULT_RECENT_LIMIT));
   }
 
+  /**
+   * Bumped by every mutating method. The app layer repaints when this changed
+   * (plus on resize and on the animation tick), which is what keeps an idle
+   * dashboard from redrawing itself. Writing a public field directly bypasses
+   * it, so state changes go through the methods below.
+   */
+  get revision(): number {
+    return this._revision;
+  }
+
+  private touch(): void {
+    this._revision++;
+  }
+
   // ── Data ───────────────────────────────────────────────────────────────────
 
   upsertSession(session: TuiSessionRow): void {
@@ -258,24 +275,38 @@ export class TuiModelStore implements TuiRenderModel {
   // ── Chrome ─────────────────────────────────────────────────────────────────
 
   setConnection(status: TuiConnectionStatus): void {
+    if (this.connection === status) return;
     this.connection = status;
+    this.touch();
   }
 
   setHeader(header: TuiHeaderInfo): void {
     this.header = { ...this.header, ...header };
+    this.touch();
   }
 
   setPreview(preview: TuiPreview | null): void {
     this.preview = preview;
+    this.touch();
   }
 
   setMode(mode: TuiUiMode): void {
+    if (this.mode === mode) return;
     this.mode = mode;
+    this.touch();
   }
 
   setMessage(message: TuiMessage | null): void {
     this.message = message;
     this.mode = message ? 'message' : 'list';
+    this.touch();
+  }
+
+  /** Show (or clear) the overlay chooser. Setting one takes the keyboard. */
+  setPicker(picker: TuiPickerState | null): void {
+    this.picker = picker;
+    this.mode = picker ? 'new-session' : 'list';
+    this.touch();
   }
 
   /** Arm the typed-name confirmation for `x` (kill). */
@@ -286,10 +317,13 @@ export class TuiModelStore implements TuiRenderModel {
       typed: '',
     };
     this.mode = 'confirm-kill';
+    this.touch();
   }
 
   setConfirmInput(typed: string): void {
-    if (this.confirm) this.confirm = { ...this.confirm, typed };
+    if (!this.confirm) return;
+    this.confirm = { ...this.confirm, typed };
+    this.touch();
   }
 
   /** Does the typed text authorize the kill? Exact match on the name shown. */
@@ -301,7 +335,9 @@ export class TuiModelStore implements TuiRenderModel {
   closeOverlay(): void {
     this.confirm = null;
     this.message = null;
+    this.picker = null;
     this.mode = 'list';
+    this.touch();
   }
 
   // ── Derived views ──────────────────────────────────────────────────────────
@@ -330,7 +366,7 @@ export class TuiModelStore implements TuiRenderModel {
   /** Select a session by id. Returns false when it is not on screen. */
   select(sessionId: string): boolean {
     if (!this.rows().some((row) => row.session.sessionId === sessionId)) return false;
-    this.selectedId = sessionId;
+    this.moveTo(sessionId);
     return true;
   }
 
@@ -338,17 +374,17 @@ export class TuiModelStore implements TuiRenderModel {
   moveCursor(delta: number): void {
     const rows = this.rows();
     if (rows.length === 0) {
-      this.selectedId = null;
+      this.moveTo(null);
       return;
     }
     const current = this.indexOfSelected(rows);
     if (current < 0) {
-      this.selectedId = rows[delta >= 0 ? 0 : rows.length - 1].session.sessionId;
+      this.moveTo(rows[delta >= 0 ? 0 : rows.length - 1].session.sessionId);
       return;
     }
     const step = Math.trunc(delta);
     const next = (((current + step) % rows.length) + rows.length) % rows.length;
-    this.selectedId = rows[next].session.sessionId;
+    this.moveTo(rows[next].session.sessionId);
   }
 
   /** The 1-9 jump: `n` is the 1-based position in the flattened list. */
@@ -356,10 +392,16 @@ export class TuiModelStore implements TuiRenderModel {
     const rows = this.rows();
     const index = Math.trunc(n) - 1;
     if (index < 0 || index >= rows.length) return false;
-    this.selectedId = rows[index].session.sessionId;
+    this.moveTo(rows[index].session.sessionId);
     return true;
   }
 
+  private moveTo(sessionId: string | null): void {
+    if (this.selectedId === sessionId) return;
+    this.selectedId = sessionId;
+    this.touch();
+  }
+
   private indexOfSelected(rows: readonly TuiRow[] = this.rows()): number {
     if (!this.selectedId) return -1;
     return rows.findIndex((row) => row.session.sessionId === this.selectedId);
@@ -373,14 +415,15 @@ export class TuiModelStore implements TuiRenderModel {
   private mutate(apply: () => void): void {
     const previousIndex = this.indexOfSelected();
     apply();
+    this.touch();
     const rows = this.rows();
     if (rows.length === 0) {
-      this.selectedId = null;
+      this.moveTo(null);
       return;
     }
     if (this.selectedId !== null && rows.some((row) => row.session.sessionId === this.selectedId)) return;
     const index = Math.min(Math.max(previousIndex, 0), rows.length - 1);
-    this.selectedId = rows[index].session.sessionId;
+    this.moveTo(rows[index].session.sessionId);
   }
 }
 

src/tui/tui-types.ts

@@ -33,6 +33,15 @@ export interface TuiSessionRow extends UnifiedSessionItem {
   lastSubmitAt?: number;
   inputTokens?: number;
   outputTokens?: number;
+  /**
+   * tmux session name to attach to (`codeman-<first 8 of the id>`).
+   *
+   * The unified list does not carry it (no server view merges the mux name into
+   * a row), so the app layer fills it in from the local tmux enumeration, which
+   * is also the only thing that proves the pane really exists. A row without one
+   * cannot be attached: it is either history or a direct-PTY session.
+   */
+  muxName?: string;
 }
 
 /**
@@ -68,7 +77,7 @@ export interface TuiGroup {
 export type TuiConnectionStatus = 'connected' | 'reconnecting' | 'degraded' | 'down';
 
 /** Which overlay (if any) owns the keyboard. */
-export type TuiUiMode = 'list' | 'help' | 'confirm-kill' | 'prompt' | 'search' | 'message';
+export type TuiUiMode = 'list' | 'help' | 'confirm-kill' | 'prompt' | 'search' | 'message' | 'new-session';
 
 /**
  * Glyph capability tier. Detection is env-driven and therefore lives in a tiny
@@ -107,6 +116,30 @@ export interface TuiConfirmState {
   typed: string;
 }
 
+export interface TuiPickerItem {
+  /** What choosing this item means to the caller; never shown. */
+  id: string;
+  label: string;
+  /** Second column, dimmed (a case path, a mode description). */
+  detail?: string;
+}
+
+/**
+ * A one-column chooser drawn as an overlay (the case and mode pickers behind
+ * `n`). Items are already filtered: the app owns the unfiltered list, the
+ * renderer only paints what it is given.
+ */
+export interface TuiPickerState {
+  title: string;
+  items: TuiPickerItem[];
+  /** Index into `items`; -1 when the list is empty. */
+  index: number;
+  /** Current filter text, when the picker filters as you type. */
+  filter?: string;
+  /** One line above the list: what is being chosen, or why the list is empty. */
+  hint?: string;
+}
+
 /**
  * What `renderFrame()` reads. The store implements it; a test can hand-build
  * one, which is what keeps the renderer testable without the model.
@@ -120,6 +153,8 @@ export interface TuiRenderModel {
   readonly preview: TuiPreview | null;
   readonly message: TuiMessage | null;
   readonly confirm: TuiConfirmState | null;
+  /** Optional so a test can hand-build a model without one. */
+  readonly picker?: TuiPickerState | null;
   /** Live sessions only (RECENT rows are history, not sessions you have open). */
   readonly sessionCount: number;
 }