earendil-works/pi · error

Session id must be non-empty, contain only alphanumeric…

Error message

Session id must be non-empty, contain only alphanumeric characters, '-', '_', and '.', and start and end with an alphanumeric character

What it means

Validation guard in assertValidSessionId: the given session id fails the pattern ^[A-Za-z0-9]([A-Za-z0-9._-]*[A-Za-z0-9])?$ — it is empty, contains characters other than alphanumerics, '-', '_', '.', or starts/ends with a non-alphanumeric. Called on session creation, fork, and id CLI validation, so the offending input is a user-supplied or flag-provided session id.

Solutions

1. Pass a session id matching the allowed pattern (alphanumeric start/end, only '.', '-', '_' inside)
2. Use the generated uuidv7 id from createSessionId instead of a hand-written one
3. For forkFrom, use the id of an existing session

When it happens

Trigger: Thrown at packages/coding-agent/src/core/session-manager.ts:214 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/ea80156e8d60e2d8. Report an issue: GitHub.

Appendix: source

Thrown at packages/coding-agent/src/core/session-manager.ts:214

	| "getLeafId"
	| "getLeafEntry"
	| "getEntry"
	| "getLabel"
	| "getBranch"
	| "buildContextEntries"
	| "getHeader"
	| "getEntries"
	| "getTree"
	| "getSessionName"
>;

function createSessionId(): string {
	return uuidv7();
}

export function assertValidSessionId(id: string): void {
	if (!/^[A-Za-z0-9](?:[A-Za-z0-9._-]*[A-Za-z0-9])?$/.test(id)) {
		throw new Error(
			"Session id must be non-empty, contain only alphanumeric characters, '-', '_', and '.', and start and end with an alphanumeric character",
		);
	}
}

/** Generate a unique short ID (8 hex chars, collision-checked) */
function generateId(byId: { has(id: string): boolean }): string {
	for (let i = 0; i < 100; i++) {
		const id = randomUUID().slice(0, 8);
		if (!byId.has(id)) return id;
	}
	// Fallback to full UUID if somehow we have collisions
	return randomUUID();
}

/** Migrate v1 → v2: add id/parentId tree structure. Mutates in place. */
function migrateV1ToV2(entries: FileEntry[]): void {
	const ids = new Set<string>();

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