[eslint-miner] eslint-factory: add no-unhandled-async-timer-callback rule - #65292

New rule: no-unhandled-async-timer-callback

Flags await outside a try/catch inside async setTimeout/setInterval/setImmediate callbacks (including globalThis./global. forms). Timers discard the returned promise, so a rejection becomes an unhandled rejection that can crash the Node process.

Evidence

• actions/setup/js/process_runner.cjs (~L430) uses setInterval(async () => ...) with the await correctly wrapped in try/catch/finally. The rule enforces that pattern for future timer callbacks.
• Other timer sites in actions/setup/js are synchronous, so there are no false positives today (npm run lint:setup-js reports 0 hits).
• Complements no-async-foreach-callback (same discarded-promise class of bug).
• Note: no strong recurring issue/discussion was found for this specific pattern in the last 14 days; the rule is preventive, based on the code scan.

Design

Only async function callbacks passed directly as the first timer argument; awaits in nested functions are not attributed to the timer callback; awaits in catch/finally are still reported.

Validation

npm install, npm run build, rule unit tests, and npm run lint:setup-js all pass. Registered in src/index.ts, enabled as warn in eslint.config.cjs.

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• expires on Oct 10, 2026, 12:56 AM UTC-08:00