can1357/oh-my-pi · error · ToolError

${label} failed fast after ${afterMs}ms${formatSelectorMatch

Error message

${label} failed fast after ${afterMs}ms${formatSelectorMatchHint(0)}

What it means

A wait-for-disappearance style poll confirmed the selector matches exactly 0 elements and, after reaching the deadline with zero matches still true, fails fast with this ToolError including elapsed ms and a selector match hint. It distinguishes 'element never appeared' from 'element did not disappear in time'.

Source

Thrown at packages/coding-agent/src/tools/browser/tab-worker.ts:1523

	 * matches; an inconclusive probe (mid-navigation, detached frame) never counts
	 * toward the zero-match window.
	 */
	async #zeroMatchWatchdog(selector: string, label: string, afterMs: number, signal: AbortSignal): Promise<never> {
		const page = this.#requirePage();
		const resolved = normalizeSelector(selector);
		const deadline = Date.now() + afterMs;
		while (!signal.aborted) {
			let count: number | null = null;
			try {
				const handles = await page.$$(resolved);
				count = handles.length;
				for (const handle of handles) void handle.dispose().catch(() => undefined);
			} catch {
				// Inconclusive probe — keep polling without advancing toward failure.
			}
			if (count !== null && count > 0) break;
			if (count === 0 && Date.now() >= deadline) {
				throw new ToolError(`${label} failed fast after ${afterMs}ms${formatSelectorMatchHint(0)}`);
			}
			try {
				await untilAborted(signal, () => Bun.sleep(ZERO_MATCH_POLL_MS));
			} catch {
				break;
			}
		}
		return await new Promise<never>(() => {});
	}

	/**
	 * Best-effort match-count probe for a timed-out selector op. Never throws;
	 * empty string when the probe fails, stalls, or the selector is an aria-ref.
	 */
	async #selectorTimeoutHint(selector: string): Promise<string> {
		if (parseAriaRefSelector(selector) !== null) return "";
		try {
			const handles = await Promise.race([

View on GitHub (pinned to 9690622007)

Solutions

Verify the selector actually matches elements in the intended frame (query it directly with page.$)
Check whether the element ever existed — if it should appear first, wait for appearance before waiting for disappearance
Use ariaSnapshot to inspect the current DOM and correct the selector
Increase the timeout only after confirming the element is present and the disappearance is genuinely pending

Example fix

// before
await tab.waitForSelectorGone('.spinner', { timeout: 3000 });
// after
if (await tab.$('.spinner')) {
  await tab.waitForSelectorGone('.spinner', { timeout: 10000 });
}

Defensive patterns

Strategy: validation

Validate before calling

const present = await tab.$(selector);
if (!present) throw new Error(`selector ${selector} never matched — fix it before waiting for disappearance`);

Try / catch

try {
  await waitForGone(selector, { timeout: ms });
} catch (err) {
  if (err instanceof ToolError && /failed fast/.test(err.message)) {
    // selector matched nothing from the start: treat as selector bug
    const snap = await tab.ariaSnapshot();
    logger.warn('selector never matched', { selector, snap });
  } else throw err;
}

Prevention

Confirm the element exists before waiting for it to disappear
Test selectors with page.$ or a full ariaSnapshot first
Scope selectors to the correct frame/shadow root
Distinguish 'never matched' from 'timed out waiting' when choosing timeouts

When it happens

Trigger: Waiting for an element/selector to disappear (count must reach 0) where the first probe already returned count === 0 and the fast-fail deadline (afterMs) elapsed, so the condition was satisfied-but-never-pending — typically a wrong selector that never matched anything.

Common situations: Selector typo or wrong frame/shadow-root scope so it never matches; asserting a spinner disappears when the page never rendered it; CSS/XPath mismatch after a DOM redesign.

Related errors

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/3b6a24185abaf0c8. Report an issue: GitHub.