fix(show-runtime): own automatic request recovery

[cyhhao]

Summary

• establish the successor for automatic request-level Show Runtime recovery on merged PR fix(show-runtime): bound retries and refresh recovery state #1640
• carry the browser poll loop and its request retry owner as one property
• preserve the fifth-head review constraints before reintroducing any automatic request

Stack

This draft is based on master after PR #1640 merged as 903414cc4. PR #1640 deliberately restores manual recovery and contains no automatic browser poller or request-level retry record. This successor is the only PR that may reintroduce that surface. The current commit records the seam and inherited review scope; implementation has not started.

Contract

1. One exception-closed request owner spans precondition acquisition, transport attempt, and publication, with one publication point. Only a successful request clears request evidence; startup success cannot.
2. The request owner publishes continuous, confirmation_pending, or manual_only. The browser owns pacing only and has no confirmation counter; a rejected fetch cannot consume manager admission.
3. A bound on automatic attempts never gates user-initiated work. Page loads, assets, and an authorized owner Retry-now request always attempt transport. When automatic confirmation stops, public-viewer copy names actions the viewer can take: reload, then contact the owner.
4. Polling state survives document replacement. The implementation must isolate script state or use real navigation, and must cover a non-terminal-to-non-terminal transition.
5. A terminal response renders without another Runtime request. Header absence may reload because it proves the Runtime is serving; a terminal disposition may not manufacture the automatic attempt the owner just refused.

The recovery UI must continue projecting manager-owned reason, class, disposition, and action without a fabricating fallback. Only the authenticated instance owner may authorize explicit Retry-now; public and limited viewers remain automatic and never see an owner-only action.

Inherited Review Scope

• Isolate polling state before rewriting the document
• Do not consume confirmation on a failed poll
• Render terminal state without another automatic request
• request-owner ruling: exception closure, no gating of user-initiated work, identity from preconditions Avibe does not write, and an actionable terminal message for the affected viewer

These threads are resolved on PR #1640 because their code surface moved. Their behavioral discharge and consuming tests belong to this PR's exact-head close-out.

Verification

• git diff --check
• PRD records the full inherited constraints and thread links