feat: add Tab key to cycle through thinking levels

- Add onTab callback to CustomEditor
- Implement cycleThinkingLevel() in TuiRenderer
- Only works when model supports reasoning
- Cycles through: off → minimal → low → medium → high → off
- Update footer to show current thinking level with '(tab to cycle)' hint
- Update header instructions to mention tab for thinking
- Show notification when thinking level changes

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

@@ -6,8 +6,17 @@ import { Editor } from "@mariozechner/pi-tui";
 export class CustomEditor extends Editor {
 	public onEscape?: () => void;
 	public onCtrlC?: () => void;
+	public onTab?: () => boolean;
 
 	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 Escape key - but only if autocomplete is NOT active
 		// (let parent handle escape for autocomplete cancellation)
 		if (data === "\x1b" && this.onEscape && !this.isShowingAutocomplete()) {

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

@@ -85,30 +85,41 @@ export class FooterComponent {
 
 		const statsLeft = statsParts.join(" ");
 
-		// Add model name on the right side
-		let modelName = this.state.model?.id || "no-model";
+		// Add model name on the right side, plus thinking level if model supports it
+		const modelName = this.state.model?.id || "no-model";
+
+		// Add thinking level hint if model supports reasoning
+		let rightSide = modelName;
+		if (this.state.model?.reasoning) {
+			const thinkingLevel = this.state.thinkingLevel || "off";
+			const thinkingHint = chalk.dim(" (tab to cycle)");
+			rightSide = `${modelName} • ${thinkingLevel}${thinkingHint}`;
+		}
+
 		const statsLeftWidth = visibleWidth(statsLeft);
-		const modelWidth = visibleWidth(modelName);
+		const rightSideWidth = visibleWidth(rightSide);
 
 		// Calculate available space for padding (minimum 2 spaces between stats and model)
 		const minPadding = 2;
-		const totalNeeded = statsLeftWidth + minPadding + modelWidth;
+		const totalNeeded = statsLeftWidth + minPadding + rightSideWidth;
 
 		let statsLine: string;
 		if (totalNeeded <= width) {
 			// Both fit - add padding to right-align model
-			const padding = " ".repeat(width - statsLeftWidth - modelWidth);
-			statsLine = statsLeft + padding + modelName;
+			const padding = " ".repeat(width - statsLeftWidth - rightSideWidth);
+			statsLine = statsLeft + padding + rightSide;
 		} else {
-			// Need to truncate model name
-			const availableForModel = width - statsLeftWidth - minPadding;
-			if (availableForModel > 3) {
-				// Truncate model name to fit
-				modelName = modelName.substring(0, availableForModel);
-				const padding = " ".repeat(width - statsLeftWidth - visibleWidth(modelName));
-				statsLine = statsLeft + padding + modelName;
+			// Need to truncate right side
+			const availableForRight = width - statsLeftWidth - minPadding;
+			if (availableForRight > 3) {
+				// Truncate to fit (strip ANSI codes for length calculation, then truncate raw string)
+				const plainRightSide = rightSide.replace(/\x1b\[[0-9;]*m/g, "");
+				const truncatedPlain = plainRightSide.substring(0, availableForRight);
+				// For simplicity, just use plain truncated version (loses color, but fits)
+				const padding = " ".repeat(width - statsLeftWidth - truncatedPlain.length);
+				statsLine = statsLeft + padding + truncatedPlain;
 			} else {
-				// Not enough space for model name at all
+				// Not enough space for right side at all
 				statsLine = statsLeft;
 			}
 		}

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

@@ -1,4 +1,4 @@
-import type { Agent, AgentEvent, AgentState } from "@mariozechner/pi-agent";
+import type { Agent, AgentEvent, AgentState, ThinkingLevel } from "@mariozechner/pi-agent";
 import type { AssistantMessage, Message } from "@mariozechner/pi-ai";
 import type { SlashCommand } from "@mariozechner/pi-tui";
 import {
@@ -169,6 +169,9 @@ export class TuiRenderer {
 			chalk.dim("ctrl+k") +
 			chalk.gray(" to delete line") +
 			"\n" +
+			chalk.dim("tab") +
+			chalk.gray(" to cycle thinking") +
+			"\n" +
 			chalk.dim("/") +
 			chalk.gray(" for commands") +
 			"\n" +
@@ -210,6 +213,10 @@ export class TuiRenderer {
 			this.handleCtrlC();
 		};
 
+		this.editor.onTab = () => {
+			return this.cycleThinkingLevel();
+		};
+
 		// Handle editor submission
 		this.editor.onSubmit = async (text: string) => {
 			text = text.trim();
@@ -572,6 +579,32 @@ export class TuiRenderer {
 		}
 	}
 
+	private cycleThinkingLevel(): boolean {
+		// Only cycle if model supports thinking
+		if (!this.agent.state.model?.reasoning) {
+			return false; // Not handled, let default Tab behavior continue
+		}
+
+		const levels: ThinkingLevel[] = ["off", "minimal", "low", "medium", "high"];
+		const currentLevel = this.agent.state.thinkingLevel || "off";
+		const currentIndex = levels.indexOf(currentLevel);
+		const nextIndex = (currentIndex + 1) % levels.length;
+		const nextLevel = levels[nextIndex];
+
+		// Apply the new thinking level
+		this.agent.setThinkingLevel(nextLevel);
+
+		// Save thinking level change to session
+		this.sessionManager.saveThinkingLevelChange(nextLevel);
+
+		// Show brief notification
+		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 {
 		this.editor.setText("");
 		this.ui.requestRender();