iOS smoke lane: webview cold-start exceeds the 20s first-page budget; wait_deadline_exceeded with content present in the post-failure snapshot #3343

Why

smoke:webview-remote-content fails the iOS Smoke lane at step "wait for the WebView page to expose its link" (wait text "Jump to form" 20000) with typed reason: wait_deadline_exceeded — all 25 polls outcome: readable, i.e. the route was healthy and answering the whole budget; the page content simply did not appear inside the 20 s the scenario budgets for the run's first WebContent process spawn.

The failure is self-refuting as a "content never arrives" defect: the post-failure snapshot taken seconds later already contains the page — failed-step-102-snapshot.json carries two Jump to form links, Account form, and Email address under a healthy/tree verdict with the expected circuit-disabled fallback warning. The page finished loading just past the deadline.

This is exactly the lane condition the scenario's own comment anticipates (live-webview-remote-content.ts: "a cold CI simulator needs more than the shared 10 s wait budget" — raised to 20 s), so the open question is who owns the tail: a longer/compensated budget, a load-completion signal instead of a wall-clock guess, or classifying the overrun as a lane condition under #2491. #2492 task 1 (content-class gate with fresh generations per row) would make this cheaper to pin down but does not own it.

Evidence

• Run 37843633972 (PR fix(test): make the iOS simulator smoke lane's red/green signal meaningful (#2491) #3336 lane, 98321a279, 2026-10-08T21:16:46Z). The diff is test-only and does not touch the webview scenario; wait_deadline_exceeded is deliberately non-retriable under the lane policy added in that PR, so this class stays red by design until owned here.
• Not present in the four recent main failure logs checked (37459193672, 37419258095, 37356199982, 36454269522 grep zero for Jump to form), and no ci(ios): the iOS simulator smoke lane is failing on main across several rotating signatures #2491 comment mentions web content — genuinely new signature.
• Payload: gh run download 37843633972 --repo callstack/agent-device -n ios-artifacts → test/artifacts/ios-simulator/smoke/1791493983644-15998/failed-step.txt (poll table) and failed-step-102-snapshot.json (content present post-deadline).

Scope

Decide the owner of the WebContent cold-start tail for the first page of an app generation (budget, load signal, or explicit lane classification per #2491), then make the step's red/green signal match that decision. Do not just raise the constant without saying why the tail is what it is.

Related: #2491, #2492, #2484, #3336 (lane policy that leaves this red), #3342 (other untracked PR-lane class).