feat(cli): implement dynamic terminal tab titles for CLI status (#16378)

packages/cli/src/utils/windowTitle.ts

@@ -4,19 +4,104 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { StreamingState } from '../ui/types.js';
+
+export interface TerminalTitleOptions {
+  streamingState: StreamingState;
+  thoughtSubject?: string;
+  isConfirming: boolean;
+  folderName: string;
+  showThoughts: boolean;
+  useDynamicTitle: boolean;
+}
+
+function truncate(text: string, maxLen: number): string {
+  if (text.length <= maxLen) {
+    return text;
+  }
+  return text.substring(0, maxLen - 1) + '…';
+}
+
 /**
- * Computes the window title for the Gemini CLI application.
+ * Computes the dynamic terminal window title based on the current CLI state.
  *
- * @param folderName - The name of the current folder/workspace to display in the title
- * @returns The computed window title, either from CLI_TITLE environment variable or the default Gemini title
+ * @param options - The current state of the CLI and environment context
+ * @returns A formatted string padded to 80 characters for the terminal title
  */
-export function computeWindowTitle(folderName: string): string {
-  const title = process.env['CLI_TITLE'] || `Gemini - ${folderName}`;
+export function computeTerminalTitle({
+  streamingState,
+  thoughtSubject,
+  isConfirming,
+  folderName,
+  showThoughts,
+  useDynamicTitle,
+}: TerminalTitleOptions): string {
+  const MAX_LEN = 80;
+
+  // Use CLI_TITLE env var if available, otherwise use the provided folder name
+  let displayContext = process.env['CLI_TITLE'] || folderName;
+
+  if (!useDynamicTitle) {
+    const base = 'Gemini CLI ';
+    // Max context length is 80 - base.length - 2 (for brackets)
+    const maxContextLen = MAX_LEN - base.length - 2;
+    displayContext = truncate(displayContext, maxContextLen);
+    return `${base}(${displayContext})`.padEnd(MAX_LEN, ' ');
+  }
+
+  // Pre-calculate suffix but keep it flexible
+  const getSuffix = (context: string) => ` (${context})`;
+
+  let title;
+  if (
+    isConfirming ||
+    streamingState === StreamingState.WaitingForConfirmation
+  ) {
+    const base = '✋  Action Required';
+    // Max context length is 80 - base.length - 3 (for ' (' and ')')
+    const maxContextLen = MAX_LEN - base.length - 3;
+    const context = truncate(displayContext, maxContextLen);
+    title = `${base}${getSuffix(context)}`;
+  } else if (streamingState === StreamingState.Idle) {
+    const base = '◇  Ready';
+    // Max context length is 80 - base.length - 3 (for ' (' and ')')
+    const maxContextLen = MAX_LEN - base.length - 3;
+    const context = truncate(displayContext, maxContextLen);
+    title = `${base}${getSuffix(context)}`;
+  } else {
+    // Active/Working state
+    const cleanSubject =
+      showThoughts && thoughtSubject?.replace(/[\r\n]+/g, ' ').trim();
+
+    // If we have a thought subject and it's too long to fit with the suffix,
+    // we drop the suffix to maximize space for the thought.
+    // Otherwise, we keep the suffix.
+    const suffix = getSuffix(displayContext);
+    const suffixLen = suffix.length;
+    const canFitThoughtWithSuffix = cleanSubject
+      ? cleanSubject.length + suffixLen + 3 <= MAX_LEN
+      : true;
+
+    let activeSuffix = '';
+    let maxStatusLen = MAX_LEN - 3; // Subtract icon prefix "✦  " (3 chars)
+
+    if (!cleanSubject || canFitThoughtWithSuffix) {
+      activeSuffix = suffix;
+      maxStatusLen -= activeSuffix.length;
+    }
+
+    const displayStatus = cleanSubject
+      ? truncate(cleanSubject, maxStatusLen)
+      : 'Working…';
+
+    title = `✦  ${displayStatus}${activeSuffix}`;
+  }
 
   // Remove control characters that could cause issues in terminal titles
-  return title.replace(
-    // eslint-disable-next-line no-control-regex
-    /[\x00-\x1F\x7F]/g,
-    '',
-  );
+  // eslint-disable-next-line no-control-regex
+  const safeTitle = title.replace(/[\x00-\x1F\x7F]/g, '');
+
+  // Pad the title to a fixed width to prevent taskbar icon resizing/jitter.
+  // We also slice it to ensure it NEVER exceeds MAX_LEN.
+  return safeTitle.padEnd(MAX_LEN, ' ').substring(0, MAX_LEN);
 }