perf: smart-wait — waitForCapture, wait({ selector }), daemon backoff

[jackwener]

Summary

Three-layer performance optimization eliminating unnecessary fixed sleeps:

• Layer 1 – waitForCapture(): New IPage method that polls window.__opencli_xhr every 100ms and resolves as soon as the first network capture arrives (instead of blind wait(N)). Fixes a correctness bug where DOM-stable detection would resolve before the API response arrived. Replaces wait(N) in 7 INTERCEPT adapters (36kr, twitter/followers, twitter/following, twitter/notifications, producthunt) and in stepIntercept pipeline step.

• Layer 2 – wait({ selector }): Extends WaitOptions with selector?: string and adds waitForSelectorJs() (polls querySelector every 100ms). Replaces blind wait(5) React hydration waits in 15 Twitter UI adapters and 8 calls across medium/substack/bloomberg/sinablog.

• Layer 3 – daemon exponential backoff: Replaces fixed 300ms poll in _ensureDaemon() with [50, 100, 200, 400, 800, 1500, 3000] backoff — a connected extension is detected ~250ms faster on average.

Changes

File	Change
src/browser/dom-helpers.ts	Add waitForCaptureJs(), waitForSelectorJs()
src/types.ts	Add selector? to WaitOptions, waitForCapture() to IPage
src/browser/page.ts	Implement waitForCapture(), wait({ selector })
src/browser/cdp.ts	Same as page.ts
src/pipeline/steps/intercept.ts	Use installInterceptor + waitForCapture + getInterceptedRequests
7 INTERCEPT adapters	wait(N) → waitForCapture(N)
15 Twitter UI adapters	wait(5) → wait({ selector: '[data-testid="primaryColumn"]' })
medium/substack/bloomberg/sinablog	wait(N) → wait({ selector, timeout: N })
src/browser/mcp.ts	Exponential backoff for daemon cold-start

Test plan

• npx vitest run --project unit --project adapter — 91 files, 707 tests, all pass
• npx tsc --noEmit — zero type errors
• 7 new unit tests for waitForCaptureJs and waitForSelectorJs in dom-helpers.test.ts