earendil-works/pi · error

Cannot fork: source session has no header: ${resolvedSourceP

Error message

Cannot fork: source session has no header: ${resolvedSourcePath}

What it means

Error "Cannot fork: source session has no header: ${resolvedSourcePath}" thrown in earendil-works/pi.

Source

Thrown at packages/coding-agent/src/core/session-manager.ts:1595

	 * @param targetCwd Target working directory (where the new session will be stored)
	 * @param sessionDir Optional session directory. If omitted, uses default for targetCwd.
	 */
	static forkFrom(
		sourcePath: string,
		targetCwd: string,
		sessionDir?: string,
		options?: NewSessionOptions,
	): SessionManager {
		const resolvedSourcePath = resolvePath(sourcePath);
		const resolvedTargetCwd = resolvePath(targetCwd);
		const sourceEntries = loadEntriesFromFile(resolvedSourcePath);
		if (sourceEntries.length === 0) {
			throw new Error(`Cannot fork: source session file is empty or invalid: ${resolvedSourcePath}`);
		}

		const sourceHeader = sourceEntries.find((e) => e.type === "session") as SessionHeader | undefined;
		if (!sourceHeader) {
			throw new Error(`Cannot fork: source session has no header: ${resolvedSourcePath}`);
		}

		const dir = sessionDir ? normalizePath(sessionDir) : getDefaultSessionDir(resolvedTargetCwd);
		if (!existsSync(dir)) {
			mkdirSync(dir, { recursive: true });
		}

		// Create new session file with new ID but forked content
		if (options?.id !== undefined) {
			assertValidSessionId(options.id);
		}
		const newSessionId = options?.id ?? createSessionId();
		const timestamp = new Date().toISOString();
		const fileTimestamp = timestamp.replace(/[:.]/g, "-");
		const newSessionFile = join(dir, `${fileTimestamp}_${newSessionId}.jsonl`);

		// Write new header pointing to source as parent, with updated cwd
		const newHeader: SessionHeader = {

View on GitHub (pinned to 4af9d21d3b)

When it happens

Trigger: Thrown at packages/coding-agent/src/core/session-manager.ts:1595 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of earendil-works/pi@4af9d21d3b (2026-08-24). Data as JSON: /api/errors/e216e68029103117. Report an issue: GitHub.