[olddonkey]

Amex signs an idle tab out after a few minutes, which can cut a long multi-card run short. This adds an opt-in keep-alive, toggled from a header button and off by default (persisted in localStorage).

What it does

While on, it keeps the session warm entirely on the client — it makes no network request of its own — by:

• Swallowing the page's logout signals (visibilitychange / webkitvisibilitychange / blur / pagehide / freeze) in the capture phase on window, so the site keeps believing the tab is visible and focused. Fully reversible when toggled back off.
• Nudging the page's inactivity manager (window.timeout) once a minute, falling back to synthetic focus / mousemove activity when no manager is present.

eslint.config.mjs: allow the globals the feature uses (setInterval, clearInterval, Event, MouseEvent).

⚠️ Reviewer note — this needs the MAIN world in the extension

The nudge reads window.timeout, a page main-world global. That works in the Tampermonkey userscript (@grant none → main world), but the Chrome extension ships as an isolated-world content script by default, where window.timeout is unreachable — so the nudge half degrades to synthetic events there.

If keep-alive should work fully in the extension, build it with the existing escape hatch:

EXT_WORLD=MAIN npm run build

The event-suppression half works in either world (shared DOM dispatch). Decide whether to ship the extension as MAIN-world for this feature, or accept the degraded nudge — no manifest change is made here.

Verification

• npm run lint clean, npm test 77 passing, npm run build → dist/amex-assistant-1.4.0.zip.
• Behavior (event suppression + window.timeout nudge) only fully observable on global.americanexpress.com — worth a real-page check.

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