feat(coding-agent): auto-generate session title via /rename

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## [Unreleased]
 
+### Added
+
+- `/rename` without argument auto-generates a session title using the smol model based on recent conversation context
 ## [14.5.3] - 2026-04-27
 
 ### Added

packages/coding-agent/src/modes/controllers/command-controller.ts

@@ -35,7 +35,16 @@ import { replaceTabs } from "../../tools/render-utils";
 import { getChangelogPath, parseChangelog } from "../../utils/changelog";
 import { copyToClipboard } from "../../utils/clipboard";
 import { openPath } from "../../utils/open";
-import { setSessionTerminalTitle } from "../../utils/title-generator";
+import { regenerateSessionTitle, setSessionTerminalTitle } from "../../utils/title-generator";
+
+/** Extract text content from any message type. */
+function extractMessageText(msg: { content: string | { type: string; text?: string }[] }): string {
+	if (typeof msg.content === "string") return msg.content;
+	return msg.content
+		.filter(c => c.type === "text" && c.text)
+		.map(c => c.text!)
+		.join("");
+}
 
 function showMarkdownPanel(ctx: InteractiveModeContext, title: string, markdown: string): void {
 	ctx.chatContainer.addChild(new Spacer(1));
@@ -702,9 +711,117 @@ export class CommandController {
 		}
 	}
 
-	async handleRenameCommand(title: string): Promise<void> {
+	async handleRenameCommand(title?: string): Promise<void> {
+		const wasManual = title !== undefined;
 		try {
-			const stored = await this.ctx.sessionManager.setSessionName(title, "user");
+			if (!title) {
+				// Build compact context summary from recent conversation
+				const messages = this.ctx.session.messages;
+				if (!messages.some(m => m.role === "user")) {
+					this.ctx.showError("No messages yet \u2014 provide a title manually.");
+					return;
+				}
+				const MAX_PAIRS = 5;
+				const lines: string[] = [];
+				const toolNames = new Set<string>();
+
+				// Walk messages: for each user message, grab the next assistant first-line
+				const pairs: { user: string; assistant?: string }[] = [];
+				for (let i = 0; i < messages.length; i++) {
+					const msg = messages[i];
+					if (msg.role === "toolResult") {
+						const toolMsg = msg as { toolName?: string };
+						if (toolMsg.toolName) toolNames.add(toolMsg.toolName);
+						continue;
+					}
+					if (msg.role !== "user") continue;
+					const userText = extractMessageText(msg).trim();
+					if (!userText) continue;
+
+					// Find the next assistant message after this user message
+					let assistantLine: string | undefined;
+					for (let j = i + 1; j < messages.length; j++) {
+						const next = messages[j];
+						if (next.role === "user") break;
+						if (next.role === "toolResult") {
+							const toolMsg = next as { toolName?: string };
+							if (toolMsg.toolName) toolNames.add(toolMsg.toolName);
+							continue;
+						}
+						if (next.role === "assistant") {
+							const fullText = extractMessageText(next).trim();
+							if (fullText) {
+								// First meaningful non-heading line
+								assistantLine = fullText.split("\n").find(l => l.trim() && !l.startsWith("#")) ?? "";
+							}
+							break;
+						}
+					}
+
+					pairs.push({ user: userText, assistant: assistantLine });
+				}
+
+				// Last N pairs for recency
+				const selected = pairs.slice(-MAX_PAIRS);
+				for (const pair of selected) {
+					lines.push(`user: ${pair.user}`);
+					if (pair.assistant) lines.push(`assistant: ${pair.assistant}`);
+				}
+
+				if (toolNames.size > 0) {
+					lines.push(`Tools used: ${[...toolNames].slice(-15).join(", ")}`);
+				}
+
+				// Add compaction summary as context
+				const entries = this.ctx.sessionManager.getEntries();
+				const compactionEntry = entries.findLast(
+					e => e.type === "compaction" && typeof (e as { shortSummary?: string }).shortSummary === "string",
+				);
+				if (compactionEntry) {
+					lines.push(`Summary: ${(compactionEntry as { shortSummary: string }).shortSummary}`);
+				}
+
+				const contextSummary = lines.join("\n");
+				const projectName = path.basename(this.ctx.sessionManager.getCwd());
+				const loader = new Loader(
+					this.ctx.ui,
+					s => theme.fg("accent", s),
+					t => theme.fg("muted", t),
+					"Generating title...",
+				);
+				this.ctx.statusContainer.addChild(loader);
+				this.ctx.ui.requestRender();
+				try {
+					title =
+						(await regenerateSessionTitle(
+							contextSummary,
+							this.ctx.sessionManager.getSessionName(),
+							this.ctx.session.modelRegistry,
+							this.ctx.settings,
+							this.ctx.session.sessionId,
+							this.ctx.session.model,
+							projectName,
+						)) ?? undefined;
+				} finally {
+					loader.stop();
+					this.ctx.statusContainer.clear();
+				}
+
+				if (!title) {
+					this.ctx.showError("Could not generate a title. Try /rename <title> instead.");
+					return;
+				}
+			}
+
+			// Same-title guard: if auto-generated title matches current, skip the update
+			const currentName = this.ctx.sessionManager.getSessionName();
+			if (!wasManual && currentName && title.toLowerCase() === currentName.toLowerCase()) {
+				this.ctx.showStatus("Title unchanged.");
+				return;
+			}
+
+			const source = wasManual ? "user" : "auto";
+			const stored = await this.ctx.sessionManager.setSessionName(title, source);
 			if (!stored) {
 				this.ctx.showError("Session name cannot be empty.");
 				return;
@@ -713,7 +830,8 @@ export class CommandController {
 			setSessionTerminalTitle(name, this.ctx.sessionManager.getCwd(), this.ctx.sessionManager.titleSource);
 			this.ctx.statusLine.invalidate();
 			this.ctx.updateEditorBorderColor();
-			this.ctx.showStatus(`Session renamed to "${name}".`);
+			const verb = source === "auto" ? "Title generated" : "Session renamed to";
+			this.ctx.showStatus(`${verb} "${name}".`);
 		} catch (err) {
 			this.ctx.showError(`Rename failed: ${err instanceof Error ? err.message : String(err)}`);
 		}

packages/coding-agent/src/modes/interactive-mode.ts

@@ -1349,7 +1349,7 @@ export class InteractiveMode implements InteractiveModeContext {
 		return this.#commandController.handleMoveCommand(targetPath);
 	}
 
-	handleRenameCommand(title: string): Promise<void> {
+	handleRenameCommand(title?: string): Promise<void> {
 		return this.#commandController.handleRenameCommand(title);
 	}
 

packages/coding-agent/src/modes/types.ts

@@ -190,7 +190,7 @@ export interface InteractiveModeContext {
 	handleCompactCommand(customInstructions?: string): Promise<void>;
 	handleHandoffCommand(customInstructions?: string): Promise<void>;
 	handleMoveCommand(targetPath: string): Promise<void>;
-	handleRenameCommand(title: string): Promise<void>;
+	handleRenameCommand(title?: string): Promise<void>;
 	handleMemoryCommand(text: string): Promise<void>;
 	handleSTTToggle(): Promise<void>;
 	executeCompaction(customInstructionsOrOptions?: string | CompactOptions, isAuto?: boolean): Promise<void>;

packages/coding-agent/src/prompts/system/title-system.md

@@ -1,2 +1,11 @@
-Generate a very short title (3-6 words) for a coding session based on the user's first message. The title **MUST** capture the main task or topic.
-You **MUST** output ONLY the title, nothing else. You **MUST NOT** include quotes or punctuation at the end.
+Generate a short title (3-6 words) for a coding session. Title case.
+{{#if currentTitle}}
+Current title: "{{currentTitle}}"
+{{/if}}{{#if projectName}}
+Project: {{projectName}}
+{{/if}}
+
+Rules:
+- Output ONLY the title — no quotes, no trailing punctuation
+- Focus on the most recent and important activities; use technical terms
+- If multiple topics: pick the dominant one, or the most recent if equally weighted

packages/coding-agent/src/slash-commands/builtin-registry.ts

@@ -596,16 +596,11 @@ const BUILTIN_SLASH_COMMAND_REGISTRY: ReadonlyArray<BuiltinSlashCommandSpec> = [
 	},
 	{
 		name: "rename",
-		description: "Rename the current session",
-		inlineHint: "<title>",
+		description: "Rename the current session (auto-generates title if omitted)",
+		inlineHint: "[title]",
 		allowArgs: true,
 		handle: async (command, runtime) => {
-			const title = command.args.trim();
-			if (!title) {
-				runtime.ctx.showError("Usage: /rename <title>");
-				runtime.ctx.editor.setText("");
-				return;
-			}
+			const title = command.args.trim() || undefined;
 			runtime.ctx.editor.setText("");
 			await runtime.ctx.handleRenameCommand(title);
 		},

packages/coding-agent/src/utils/title-generator.ts

@@ -12,9 +12,7 @@ import type { Settings } from "../config/settings";
 import titleSystemPrompt from "../prompts/system/title-system.md" with { type: "text" };
 import { toReasoningEffort } from "../thinking";
 
-const TITLE_SYSTEM_PROMPT = prompt.render(titleSystemPrompt);
-
-const DEFAULT_TERMINAL_TITLE = "π";
+const DEFAULT_TERMINAL_TITLE = "\u03C0";
 const TERMINAL_TITLE_CONTROL_CHARS = /[\u0000-\u001f\u007f-\u009f]/g;
 
 const MAX_INPUT_CHARS = 2000;
@@ -39,16 +37,25 @@ function getTitleModel(
 	return undefined;
 }
 
+/** Clean up model-generated title text. */
+function cleanTitle(raw: string): string | null {
+	let title = raw.trim();
+	if (!title) return null;
+	// Strip leading markdown heading markers and common LLM artifacts
+	title = title
+		.replace(/^#+\s*/, "")
+		.replace(/^["']|["']$/g, "")
+		.replace(/[.!?]$/, "");
+	return title || null;
+}
+
 /**
- * Generate a title for a session based on the first user message.
- *
- * @param firstMessage The first user message
- * @param registry Model registry
- * @param settings Settings used to resolve the smol role, including per-role thinking
- * @param sessionId Optional session id for sticky API key selection
+ * Shared LLM call for title generation.
+ * Resolves model, API key, calls completeSimple, and cleans the result.
  */
-export async function generateSessionTitle(
-	firstMessage: string,
+async function callTitleModel(
+	userMessage: string,
+	template: { currentTitle?: string; projectName?: string },
 	registry: ModelRegistry,
 	settings: Settings,
 	sessionId?: string,
@@ -60,36 +67,25 @@ export async function generateSessionTitle(
 		return null;
 	}
 
-	// Truncate message if too long
-	const truncatedMessage =
-		firstMessage.length > MAX_INPUT_CHARS ? `${firstMessage.slice(0, MAX_INPUT_CHARS)}…` : firstMessage;
-	const userMessage = `<user-message>
-${truncatedMessage}
-</user-message>`;
-
 	const apiKey = await registry.getApiKey(candidate.model, sessionId);
 	if (!apiKey) {
-		logger.debug("title-generator: no API key for smol model", {
+		logger.debug("title-generator: no API key", {
 			provider: candidate.model.provider,
 			id: candidate.model.id,
 		});
 		return null;
 	}
 
-	const request = {
-		model: `${candidate.model.provider}/${candidate.model.id}`,
-		systemPrompt: TITLE_SYSTEM_PROMPT,
-		userMessage,
-		maxTokens: 30,
-	};
-	logger.debug("title-generator: request", request);
+	const systemPrompt = prompt.render(titleSystemPrompt, template);
+	const model = `${candidate.model.provider}/${candidate.model.id}`;
+	logger.debug("title-generator: request", { model, userMessage });
 
 	try {
 		const response = await completeSimple(
 			candidate.model,
 			{
-				systemPrompt: request.systemPrompt,
-				messages: [{ role: "user", content: request.userMessage, timestamp: Date.now() }],
+				systemPrompt,
+				messages: [{ role: "user", content: userMessage, timestamp: Date.now() }],
 			},
 			{
 				apiKey,
@@ -99,43 +95,76 @@ ${truncatedMessage}
 		);
 
 		if (response.stopReason === "error") {
-			logger.debug("title-generator: response error", {
-				model: request.model,
-				stopReason: response.stopReason,
-				errorMessage: response.errorMessage,
-			});
+			logger.debug("title-generator: response error", { model, errorMessage: response.errorMessage });
 			return null;
 		}
 
 		let title = "";
 		for (const content of response.content) {
-			if (content.type === "text") {
-				title += content.text;
-			}
+			if (content.type === "text") title += content.text;
 		}
-		title = title.trim();
 
 		logger.debug("title-generator: response", {
-			model: request.model,
+			model,
 			title,
 			usage: response.usage,
 			stopReason: response.stopReason,
 		});
-
-		if (!title) {
-			return null;
-		}
-
-		return title.replace(/^["']|["']$/g, "").replace(/[.!?]$/, "");
+		return cleanTitle(title);
 	} catch (err) {
-		logger.debug("title-generator: error", {
-			model: request.model,
-			error: err instanceof Error ? err.message : String(err),
-		});
+		logger.debug("title-generator: error", { model, error: err instanceof Error ? err.message : String(err) });
 		return null;
 	}
 }
 
+/**
+ * Generate a title for a session based on the first user message.
+ */
+export async function generateSessionTitle(
+	firstMessage: string,
+	registry: ModelRegistry,
+	settings: Settings,
+	sessionId?: string,
+	currentModel?: Model<Api>,
+): Promise<string | null> {
+	const truncated =
+		firstMessage.length > MAX_INPUT_CHARS ? `${firstMessage.slice(0, MAX_INPUT_CHARS)}\u2026` : firstMessage;
+	return callTitleModel(
+		`<user-message>\n${truncated}\n</user-message>`,
+		{},
+		registry,
+		settings,
+		sessionId,
+		currentModel,
+	);
+}
+
+/**
+ * Re-generate a session title from a compact context summary.
+ * Uses the same prompt but passes currentTitle and projectName as template context
+ * so the model can decide whether the title still fits.
+ */
+export async function regenerateSessionTitle(
+	contextSummary: string,
+	currentTitle: string | undefined,
+	registry: ModelRegistry,
+	settings: Settings,
+	sessionId?: string,
+	currentModel?: Model<Api>,
+	projectName?: string,
+): Promise<string | null> {
+	if (!contextSummary.trim()) return null;
+
+	return callTitleModel(
+		`<session-context>\n${contextSummary}\n</session-context>`,
+		{ currentTitle, projectName },
+		registry,
+		settings,
+		sessionId,
+		currentModel,
+	);
+}
+
 /**
  * Remove control characters so model-generated titles cannot inject terminal escapes.
  */