feat(tui): enhance model selection and improve UI components

- Added tests for handling key events in model selector, including Enter and ArrowDown functionality.
- Updated TUI layout to include a new header, activity bar, and improved status bar with spinner and uptime.
- Refactored transcript rendering to support markdown and improved message display.
- Introduced overlays for model selection, help, and editor with appropriate rendering logic.
- Implemented smoke tests for various TUI states to ensure UI integrity and functionality.

src/interfaces/tui/state.ts

@@ -43,6 +43,8 @@ export const COMMANDS: string[] = [
   "/todo",
   "/usage",
   "/compact",
+  "/diff",
+  "/plan",
 ];
 
 /** The user's input buffer, cursor, history, and autocomplete state. */
@@ -194,6 +196,12 @@ export class InputState {
     return result;
   }
 
+  /** Clear the input buffer and reset the cursor. */
+  clear(): void {
+    this.buffer = "";
+    this.cursor = 0;
+  }
+
   /** Navigate backward through input history. */
   historyUp(): void {
     if (this.history.length === 0) return;
@@ -277,6 +285,20 @@ export class EditorState {
   }
 }
 
+/* ── Turn activity ────────────────────────────────────────────────── */
+
+/** A compact, bounded breadcrumb of agent activity during a turn. */
+export interface ActivityEntry {
+  /** Short label, e.g. a tool name or agent name. */
+  label: string;
+  /** Optional detail (current tool, error). */
+  detail?: string;
+  /** Dramatic colouring: "tool" | "agent" | "error". */
+  kind: "tool" | "agent" | "error";
+  /** Number of consecutive repeats (collapsed into one chip). */
+  count?: number;
+}
+
 /* ── Misc state ───────────────────────────────────────────────────── */
 
 /** The "miscellaneous" slice of app state. */
@@ -296,6 +318,8 @@ export class MiscState {
   pendingClipboardCopy: string | null = null;
   diffContent = "";
   diffScroll = 0;
+  /** Breadcrumb of the current turn's activity (tools / sub-agents). */
+  activity: ActivityEntry[] = [];
 
   pushToast(toast: { kind: string; message: string; createdMs: number; ttlMs: number }): void {
     this.toasts.push(toast);
@@ -477,6 +501,8 @@ export interface AppStateRest {
   turnAbort: AbortController | null;
   /** Token usage from the most recent turn (surfaced in the status bar). */
   lastUsage: { tokensIn: number; tokensOut: number } | null;
+  /** Monotonic boot time (ms) used for the status-bar uptime + spinner. */
+  bootedAt: number;
 }
 
 export const DEFAULT_HELP_TEXT = ` Zesdex TUI — Keyboard Shortcuts
@@ -487,6 +513,7 @@ export const DEFAULT_HELP_TEXT = ` Zesdex TUI — Keyboard Shortcuts
   Ctrl+Y        Copy last assistant message
   Esc           Abort turn / Close overlay
   Tab           Autocomplete
+  Alt+D         Show git diff
 
  ─── Navigation ───
   ↑ / ↓         History browse / Overlay navigate
@@ -496,20 +523,24 @@ export const DEFAULT_HELP_TEXT = ` Zesdex TUI — Keyboard Shortcuts
 
  ─── Overlays ───
   /help         Show this help
-  /settings     Open settings overlay
   /todo         Open tasks (todo) overlay
   /usage        Open usage statistics
-  /bash         Open bash jobs overlay
+  /diff         Open git diff overlay
+  /plan         Open plan overlay
   /mcp          Open MCP server management
   /model        Open model selector
   /compact      Compact conversation
   /clear        Clear transcript
-  /rewind       Rewind conversation history
 
  ─── Editor Mode ───
   /edit <path>  Open file for inline editing
-  Ctrl+S        Save changes
-  Esc           Dismiss editor`;
+  Ctrl+S        Save changes (not yet wired)
+  Esc           Dismiss editor
+
+ ─── Legend ───
+  ● running    turn is being executed
+  ● idle       waiting for input
+  in:/out:     token usage of the latest turn`;
 
 /** Construct fresh TUI state. */
 export function createTuiState(
@@ -549,6 +580,7 @@ export function createTuiState(
     turnRunner: null,
     turnAbort: null,
     lastUsage: null,
+    bootedAt: Date.now(),
   };
 }