snap/read returns 0 elements on heavy JS SPAs (YouTube, X, Coupang)

[kiyeonjeon21]

Problem

snact snap captures the DOM at Page.loadEventFired, which fires after the initial HTML loads. On heavy JS SPAs like YouTube, Twitter/X, and Coupang, the actual content is rendered asynchronously after this event — so snap sees an empty or near-empty page.

Tested sites with 0 or minimal elements

Site	Elements	Root cause
YouTube (youtube.com)	3	SPA — content rendered after load event
Twitter/X (x.com/explore)	0	Auth wall + SPA rendering
Coupang (coupang.com)	0	Bot detection + SPA
Amazon (amazon.com/dp/...)	4	Bot detection

Sites like Reddit (SPA but server-rendered), GitHub (SPA with SSR), and Vercel (Next.js) work fine because their initial HTML includes meaningful content.

Proposed solution

Add a --wait strategy option to snap and read:

# Wait for network to be idle (no requests for 500ms)
snact snap https://youtube.com --wait=networkidle

# Wait for a specific selector to appear
snact snap https://youtube.com --wait="#contents"

# Wait N milliseconds after load
snact snap https://youtube.com --wait=3000

Implementation notes

• Network idle: Use CDP Network.requestWillBeSent / Network.loadingFinished events to detect when all network activity settles. Wait until no new requests for 500ms.
• Selector wait: Use DOM.querySelector in a polling loop (already have this pattern in action/wait.rs).
• Timeout wait: Simple tokio::time::sleep.
• The existing snact wait command already handles selector and navigation waits — this would integrate similar logic into snap/read as a pre-step.

What this does NOT solve

• Bot detection (Coupang, Amazon): These sites actively block headless/automated browsers. This is outside snact's scope — users should use a real browser session with snact session load.
• Auth walls (Twitter/X when logged out): Users need to log in via the browser first.

Priority

Medium — most popular sites (GitHub, Reddit, StackOverflow, Wikipedia, Google, news sites) already work. This primarily affects YouTube-class pure SPAs where SSR is minimal.

[kiyeonjeon21]

Partial workaround exists now: snact wait <selector> or snact wait <ms> before snapping works for most SPA cases.

snact wait "#contents" && snact snap https://youtube.com

Action commands (click/fill/etc) also have built-in settle detection — 3s for navigations, 300ms for SPA DOM mutations.

What's still missing: a --wait flag directly on snap/read so you don't need two commands. That's the remaining piece.