feat(coding-agent): add session naming via /name command and extension API

- Add SessionInfoEntry type for session metadata
- Add /name <name> command to set session display name
- Add pi.setSessionName() and pi.getSessionName() extension API
- Session selector shows name (in warning color) instead of first message when set
- Session name included in fuzzy search
- /session command displays name when set

closes #650

packages/coding-agent/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Added
 
+- Session naming: `/name <name>` command sets a display name shown in the session selector instead of the first message. Useful for distinguishing forked sessions. Extensions can use `pi.setSessionName()` and `pi.getSessionName()`. ([#650](https://github.com/badlogic/pi-mono/pull/650) by [@scutifer](https://github.com/scutifer))
 - Extension example: `notify.ts` for desktop notifications via OSC 777 escape sequence ([#658](https://github.com/badlogic/pi-mono/pull/658) by [@ferologics](https://github.com/ferologics))
 - Inline hint for queued messages showing the `Alt+Up` restore shortcut ([#657](https://github.com/badlogic/pi-mono/pull/657) by [@tmustier](https://github.com/tmustier))
 

packages/coding-agent/README.md

@@ -240,6 +240,7 @@ The agent reads, writes, and edits files, and executes commands via bash.
 | `/export [file]` | Export session to self-contained HTML |
 | `/share` | Upload session as secret GitHub gist, get shareable URL (requires `gh` CLI) |
 | `/session` | Show session info: path, message counts, token usage, cost |
+| `/name <name>` | Set session display name (shown in session selector) |
 | `/hotkeys` | Show all keyboard shortcuts |
 | `/changelog` | Display full version history |
 | `/tree` | Navigate session tree in-place (search, filter, label entries) |

packages/coding-agent/docs/extensions.md

@@ -797,6 +797,25 @@ pi.on("session_start", async (_event, ctx) => {
 
 **Examples:** [plan-mode.ts](../examples/extensions/plan-mode.ts), [preset.ts](../examples/extensions/preset.ts), [snake.ts](../examples/extensions/snake.ts), [tools.ts](../examples/extensions/tools.ts)
 
+### pi.setSessionName(name)
+
+Set the session display name (shown in session selector instead of first message).
+
+```typescript
+pi.setSessionName("Refactor auth module");
+```
+
+### pi.getSessionName()
+
+Get the current session name, if set.
+
+```typescript
+const name = pi.getSessionName();
+if (name) {
+  console.log(`Session: ${name}`);
+}
+```
+
 ### pi.registerCommand(name, options)
 
 Register a command.

packages/coding-agent/docs/session.md

@@ -138,6 +138,16 @@ User-defined bookmark/marker on an entry.
 
 Set `label` to `undefined` to clear a label.
 
+### SessionInfoEntry
+
+Session metadata (e.g., user-defined display name). Set via `/name` command or `pi.setSessionName()` in extensions.
+
+```json
+{"type":"session_info","id":"k1l2m3n4","parentId":"j0k1l2m3","timestamp":"2024-12-03T14:35:00.000Z","name":"Refactor auth module"}
+```
+
+The session name is displayed in the session selector (`/resume`) instead of the first message when set.
+
 ## Tree Structure
 
 Entries form a tree:
@@ -222,6 +232,7 @@ Key methods for working with sessions programmatically:
 - `appendModelChange(provider, modelId)` - Record model change
 - `appendCompaction(summary, firstKeptEntryId, tokensBefore, details?, fromHook?)` - Add compaction
 - `appendCustomEntry(customType, data?)` - Extension state (not in context)
+- `appendSessionInfo(name)` - Set session display name
 - `appendCustomMessageEntry(customType, content, display, details?)` - Extension message (in context)
 - `appendLabelChange(targetId, label)` - Set/clear label
 
@@ -241,3 +252,4 @@ Key methods for working with sessions programmatically:
 - `buildSessionContext()` - Get messages for LLM
 - `getEntries()` - All entries (excluding header)
 - `getHeader()` - Session metadata
+- `getSessionName()` - Get display name from latest session_info entry

packages/coding-agent/src/core/extensions/loader.ts

@@ -86,6 +86,8 @@ export function createExtensionRuntime(): ExtensionRuntime {
 		sendMessage: notInitialized,
 		sendUserMessage: notInitialized,
 		appendEntry: notInitialized,
+		setSessionName: notInitialized,
+		getSessionName: notInitialized,
 		getActiveTools: notInitialized,
 		getAllTools: notInitialized,
 		setActiveTools: notInitialized,
@@ -169,6 +171,14 @@ function createExtensionAPI(
 			runtime.appendEntry(customType, data);
 		},
 
+		setSessionName(name: string): void {
+			runtime.setSessionName(name);
+		},
+
+		getSessionName(): string | undefined {
+			return runtime.getSessionName();
+		},
+
 		exec(command: string, args: string[], options?: ExecOptions) {
 			return execCommand(command, args, options?.cwd ?? cwd, options);
 		},

packages/coding-agent/src/core/extensions/runner.ts

@@ -140,6 +140,8 @@ export class ExtensionRunner {
 		this.runtime.sendMessage = actions.sendMessage;
 		this.runtime.sendUserMessage = actions.sendUserMessage;
 		this.runtime.appendEntry = actions.appendEntry;
+		this.runtime.setSessionName = actions.setSessionName;
+		this.runtime.getSessionName = actions.getSessionName;
 		this.runtime.getActiveTools = actions.getActiveTools;
 		this.runtime.getAllTools = actions.getAllTools;
 		this.runtime.setActiveTools = actions.setActiveTools;

packages/coding-agent/src/core/extensions/types.ts

@@ -727,6 +727,16 @@ export interface ExtensionAPI {
 	/** Append a custom entry to the session for state persistence (not sent to LLM). */
 	appendEntry<T = unknown>(customType: string, data?: T): void;
 
+	// =========================================================================
+	// Session Metadata
+	// =========================================================================
+
+	/** Set the session display name (shown in session selector). */
+	setSessionName(name: string): void;
+
+	/** Get the current session name, if set. */
+	getSessionName(): string | undefined;
+
 	/** Execute a shell command. */
 	exec(command: string, args: string[], options?: ExecOptions): Promise<ExecResult>;
 
@@ -797,6 +807,10 @@ export type SendUserMessageHandler = (
 
 export type AppendEntryHandler = <T = unknown>(customType: string, data?: T) => void;
 
+export type SetSessionNameHandler = (name: string) => void;
+
+export type GetSessionNameHandler = () => string | undefined;
+
 export type GetActiveToolsHandler = () => string[];
 
 export type GetAllToolsHandler = () => string[];
@@ -825,6 +839,8 @@ export interface ExtensionActions {
 	sendMessage: SendMessageHandler;
 	sendUserMessage: SendUserMessageHandler;
 	appendEntry: AppendEntryHandler;
+	setSessionName: SetSessionNameHandler;
+	getSessionName: GetSessionNameHandler;
 	getActiveTools: GetActiveToolsHandler;
 	getAllTools: GetAllToolsHandler;
 	setActiveTools: SetActiveToolsHandler;

packages/coding-agent/src/core/session-manager.ts

@@ -106,6 +106,12 @@ export interface LabelEntry extends SessionEntryBase {
 	label: string | undefined;
 }
 
+/** Session metadata entry (e.g., user-defined display name). */
+export interface SessionInfoEntry extends SessionEntryBase {
+	type: "session_info";
+	name?: string;
+}
+
 /**
  * Custom message entry for extensions to inject messages into LLM context.
  * Use customType to identify your extension's entries.
@@ -135,7 +141,8 @@ export type SessionEntry =
 	| BranchSummaryEntry
 	| CustomEntry
 	| CustomMessageEntry
-	| LabelEntry;
+	| LabelEntry
+	| SessionInfoEntry;
 
 /** Raw file entry (includes header) */
 export type FileEntry = SessionHeader | SessionEntry;
@@ -159,6 +166,8 @@ export interface SessionInfo {
 	id: string;
 	/** Working directory where the session was started. Empty string for old sessions. */
 	cwd: string;
+	/** User-defined display name from session_info entries. */
+	name?: string;
 	created: Date;
 	modified: Date;
 	messageCount: number;
@@ -180,6 +189,7 @@ export type ReadonlySessionManager = Pick<
 	| "getHeader"
 	| "getEntries"
 	| "getTree"
+	| "getSessionName"
 >;
 
 /** Generate a unique short ID (8 hex chars, collision-checked) */
@@ -511,8 +521,17 @@ async function buildSessionInfo(filePath: string): Promise<SessionInfo | null> {
 		let messageCount = 0;
 		let firstMessage = "";
 		const allMessages: string[] = [];
+		let name: string | undefined;
 
 		for (const entry of entries) {
+			// Extract session name (use latest)
+			if (entry.type === "session_info") {
+				const infoEntry = entry as SessionInfoEntry;
+				if (infoEntry.name) {
+					name = infoEntry.name.trim();
+				}
+			}
+
 			if (entry.type !== "message") continue;
 			messageCount++;
 
@@ -535,6 +554,7 @@ async function buildSessionInfo(filePath: string): Promise<SessionInfo | null> {
 			path: filePath,
 			id: (header as SessionHeader).id,
 			cwd,
+			name,
 			created: new Date((header as SessionHeader).timestamp),
 			modified: stats.mtime,
 			messageCount,
@@ -815,6 +835,32 @@ export class SessionManager {
 		return entry.id;
 	}
 
+	/** Append a session info entry (e.g., display name). Returns entry id. */
+	appendSessionInfo(name: string): string {
+		const entry: SessionInfoEntry = {
+			type: "session_info",
+			id: generateId(this.byId),
+			parentId: this.leafId,
+			timestamp: new Date().toISOString(),
+			name: name.trim(),
+		};
+		this._appendEntry(entry);
+		return entry.id;
+	}
+
+	/** Get the current session name from the latest session_info entry, if any. */
+	getSessionName(): string | undefined {
+		// Walk entries in reverse to find the latest session_info with a name
+		const entries = this.getEntries();
+		for (let i = entries.length - 1; i >= 0; i--) {
+			const entry = entries[i];
+			if (entry.type === "session_info" && entry.name) {
+				return entry.name;
+			}
+		}
+		return undefined;
+	}
+
 	/**
 	 * Append a custom message entry (for extensions) that participates in LLM context.
 	 * @param customType Extension identifier for filtering on reload

packages/coding-agent/src/index.ts

@@ -155,6 +155,7 @@ export {
 	type SessionEntryBase,
 	type SessionHeader,
 	type SessionInfo,
+	type SessionInfoEntry,
 	SessionManager,
 	type SessionMessageEntry,
 	type ThinkingLevelChangeEntry,

packages/coding-agent/src/modes/interactive/components/session-selector.ts

@@ -130,7 +130,7 @@ class SessionList implements Component {
 		this.filteredSessions = fuzzyFilter(
 			this.allSessions,
 			query,
-			(session) => `${session.id} ${session.allMessagesText} ${session.cwd}`,
+			(session) => `${session.id} ${session.name ?? ""} ${session.allMessagesText} ${session.cwd}`,
 		);
 		this.selectedIndex = Math.min(this.selectedIndex, Math.max(0, this.filteredSessions.length - 1));
 	}
@@ -167,14 +167,24 @@ class SessionList implements Component {
 			const session = this.filteredSessions[i];
 			const isSelected = i === this.selectedIndex;
 
-			// Normalize first message to single line
-			const normalizedMessage = session.firstMessage.replace(/\n/g, " ").trim();
+			// Use session name if set, otherwise first message
+			const hasName = !!session.name;
+			const displayText = session.name ?? session.firstMessage;
+			const normalizedMessage = displayText.replace(/\n/g, " ").trim();
 
 			// First line: cursor + message (truncate to visible width)
+			// Use warning color for custom names to distinguish from first message
 			const cursor = isSelected ? theme.fg("accent", "› ") : "  ";
 			const maxMsgWidth = width - 2; // Account for cursor (2 visible chars)
 			const truncatedMsg = truncateToWidth(normalizedMessage, maxMsgWidth, "...");
-			const messageLine = cursor + (isSelected ? theme.bold(truncatedMsg) : truncatedMsg);
+			let styledMsg = truncatedMsg;
+			if (hasName) {
+				styledMsg = theme.fg("warning", truncatedMsg);
+			}
+			if (isSelected) {
+				styledMsg = theme.bold(styledMsg);
+			}
+			const messageLine = cursor + styledMsg;
 
 			// Second line: metadata (dimmed) - also truncate for safety
 			const modified = formatSessionDate(session.modified);

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

@@ -286,6 +286,7 @@ export class InteractiveMode {
 			{ name: "export", description: "Export session to HTML file" },
 			{ name: "share", description: "Share session as a secret GitHub gist" },
 			{ name: "copy", description: "Copy last agent message to clipboard" },
+			{ name: "name", description: "Set session display name" },
 			{ name: "session", description: "Show session info and stats" },
 			{ name: "changelog", description: "Show changelog entries" },
 			{ name: "hotkeys", description: "Show all keyboard shortcuts" },
@@ -677,6 +678,12 @@ export class InteractiveMode {
 				appendEntry: (customType, data) => {
 					this.sessionManager.appendCustomEntry(customType, data);
 				},
+				setSessionName: (name) => {
+					this.sessionManager.appendSessionInfo(name);
+				},
+				getSessionName: () => {
+					return this.sessionManager.getSessionName();
+				},
 				getActiveTools: () => this.session.getActiveToolNames(),
 				getAllTools: () => this.session.getAllToolNames(),
 				setActiveTools: (toolNames) => this.session.setActiveToolsByName(toolNames),
@@ -1442,6 +1449,11 @@ export class InteractiveMode {
 				this.editor.setText("");
 				return;
 			}
+			if (text === "/name" || text.startsWith("/name ")) {
+				this.handleNameCommand(text);
+				this.editor.setText("");
+				return;
+			}
 			if (text === "/session") {
 				this.handleSessionCommand();
 				this.editor.setText("");
@@ -3258,10 +3270,34 @@ export class InteractiveMode {
 		}
 	}
 
+	private handleNameCommand(text: string): void {
+		const name = text.replace(/^\/name\s*/, "").trim();
+		if (!name) {
+			const currentName = this.sessionManager.getSessionName();
+			if (currentName) {
+				this.chatContainer.addChild(new Spacer(1));
+				this.chatContainer.addChild(new Text(theme.fg("dim", `Session name: ${currentName}`), 1, 0));
+			} else {
+				this.showWarning("Usage: /name <name>");
+			}
+			this.ui.requestRender();
+			return;
+		}
+
+		this.sessionManager.appendSessionInfo(name);
+		this.chatContainer.addChild(new Spacer(1));
+		this.chatContainer.addChild(new Text(theme.fg("dim", `Session name set: ${name}`), 1, 0));
+		this.ui.requestRender();
+	}
+
 	private handleSessionCommand(): void {
 		const stats = this.session.getSessionStats();
+		const sessionName = this.sessionManager.getSessionName();
 
 		let info = `${theme.bold("Session Info")}\n\n`;
+		if (sessionName) {
+			info += `${theme.fg("dim", "Name:")} ${sessionName}\n`;
+		}
 		info += `${theme.fg("dim", "File:")} ${stats.sessionFile ?? "In-memory"}\n`;
 		info += `${theme.fg("dim", "ID:")} ${stats.sessionId}\n\n`;
 		info += `${theme.bold("Messages")}\n`;

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

@@ -48,6 +48,12 @@ export async function runPrintMode(session: AgentSession, options: PrintModeOpti
 				appendEntry: (customType, data) => {
 					session.sessionManager.appendCustomEntry(customType, data);
 				},
+				setSessionName: (name) => {
+					session.sessionManager.appendSessionInfo(name);
+				},
+				getSessionName: () => {
+					return session.sessionManager.getSessionName();
+				},
 				getActiveTools: () => session.getActiveToolNames(),
 				getAllTools: () => session.getAllToolNames(),
 				setActiveTools: (toolNames: string[]) => session.setActiveToolsByName(toolNames),

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

@@ -267,6 +267,12 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 				appendEntry: (customType, data) => {
 					session.sessionManager.appendCustomEntry(customType, data);
 				},
+				setSessionName: (name) => {
+					session.sessionManager.appendSessionInfo(name);
+				},
+				getSessionName: () => {
+					return session.sessionManager.getSessionName();
+				},
 				getActiveTools: () => session.getActiveToolNames(),
 				getAllTools: () => session.getAllToolNames(),
 				setActiveTools: (toolNames: string[]) => session.setActiveToolsByName(toolNames),

packages/coding-agent/test/compaction-extensions.test.ts

@@ -108,6 +108,8 @@ describe.skipIf(!API_KEY)("Compaction extensions", () => {
 				sendMessage: async () => {},
 				sendUserMessage: async () => {},
 				appendEntry: async () => {},
+				setSessionName: () => {},
+				getSessionName: () => undefined,
 				getActiveTools: () => [],
 				getAllTools: () => [],
 				setActiveTools: () => {},