fix: change thinking level cycling from Tab to Ctrl+T

Tab key was preventing file path autocomplete from working.
Changed to Ctrl+T to avoid conflict with Tab completion.

- Tab now works normally for file/path autocomplete
- Ctrl+T cycles through thinking levels
- Shows message if model doesn't support thinking

packages/coding-agent/src/tui/custom-editor.ts

@@ -6,15 +6,13 @@ import { Editor } from "@mariozechner/pi-tui";
 export class CustomEditor extends Editor {
 	public onEscape?: () => void;
 	public onCtrlC?: () => void;
-	public onTab?: () => boolean;
+	public onCtrlT?: () => void;
 
 	handleInput(data: string): void {
-		// Intercept Tab key when autocomplete is not showing
-		if (data === "\t" && !this.isShowingAutocomplete() && this.onTab) {
-			const handled = this.onTab();
-			if (handled) {
-				return;
-			}
+		// Intercept Ctrl+T for thinking level cycling
+		if (data === "\x14" && this.onCtrlT) {
+			this.onCtrlT();
+			return;
 		}
 
 		// Intercept Escape key - but only if autocomplete is NOT active

packages/coding-agent/src/tui/tui-renderer.ts

@@ -169,7 +169,7 @@ export class TuiRenderer {
 			chalk.dim("ctrl+k") +
 			chalk.gray(" to delete line") +
 			"\n" +
-			chalk.dim("tab") +
+			chalk.dim("ctrl+t") +
 			chalk.gray(" to cycle thinking") +
 			"\n" +
 			chalk.dim("/") +
@@ -213,8 +213,8 @@ export class TuiRenderer {
 			this.handleCtrlC();
 		};
 
-		this.editor.onTab = () => {
-			return this.cycleThinkingLevel();
+		this.editor.onCtrlT = () => {
+			this.cycleThinkingLevel();
 		};
 
 		// Handle editor submission
@@ -607,10 +607,13 @@ export class TuiRenderer {
 		this.ui.requestRender();
 	}
 
-	private cycleThinkingLevel(): boolean {
+	private cycleThinkingLevel(): void {
 		// Only cycle if model supports thinking
 		if (!this.agent.state.model?.reasoning) {
-			return false; // Not handled, let default Tab behavior continue
+			this.chatContainer.addChild(new Spacer(1));
+			this.chatContainer.addChild(new Text(chalk.dim("Current model does not support thinking"), 1, 0));
+			this.ui.requestRender();
+			return;
 		}
 
 		const levels: ThinkingLevel[] = ["off", "minimal", "low", "medium", "high"];
@@ -632,8 +635,6 @@ export class TuiRenderer {
 		this.chatContainer.addChild(new Spacer(1));
 		this.chatContainer.addChild(new Text(chalk.dim(`Thinking level: ${nextLevel}`), 1, 0));
 		this.ui.requestRender();
-
-		return true; // Handled
 	}
 
 	clearEditor(): void {