Loop view: unified per-repo surface when AMS + ORB both run on the same repo

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Context

The hosted end vision has two halves — the maintainer chat platform (#9183) and the hosted AMS chat platform (#9184) — but when both products run against the same repo, the combined loop (AMS discovers work and opens PRs → ORB reviews, gates, and merges them → repeat) is the actual product story of this milestone. Neither epic owns a surface that shows the loop as one thing. The 2026-07-28 frontend planning pass (recorded on both epics) proposes an entitlement-driven app shell with two workspaces (Maintain / Build); this issue is the third, additive surface that appears only when a repo carries both entitlements.

Requirements

1. Loop timeline — one chronological per-repo feed interleaving miner events (claim, attempt, PR opened) and ORB events (review, gate verdict, merge/close), each entry linking into its product surface. Rendered from existing per-product event/audit sources — no new event taxonomy, no new SQL surfaces.
2. Loop health tile — funnel throughput: discovered → attempted → PR opened → gated → merged, with the current bottleneck stage highlighted. Figures must equal each product's own surfaces (the one-source-two-renderings rule from orb(dashboard): per-repo trust panel — ledger verify, anchor, decision records, calibration with coverage, attestation states #9193/miner-ui(hosted): per-tenant miner health/status strip and chat-groundable health tools #9199).
3. Cross-grounded chat — on a both-entitled repo the chat may ground over both products' read-tool registries; the active workspace determines default grounding only. Single-product sessions never load the other product's tools.
4. Entitlement-gated existence — the view exists only for repos where the session holds both the ORB maintainer entitlement and the AMS tenant entitlement; with one missing, the view is absent (no upsell surface here — cross-product discovery stays contextual elsewhere).
5. Privacy boundary and tenant isolation unchanged: no cross-tenant data; no wallet/hotkey/reward/trust-score/private-ranking data.

Boundaries

• Do not start before Spec: maintainer/owner conversational surface — grounding catalog, action catalog, authz matrix, placement, transport #9187's spec records the workspace/placement decisions, and both grounding registries exist (orb(chat): read-only grounding tool registry over maintainer surfaces — authz and redaction enforced by tests #9189 ORB-side, miner-ui(hosted): per-tenant chat grounding and action-dispatch authz — server-side, audited #9197 AMS-side).
• Feature-flagged off by default, like every sibling surface in the two epics.

References

Relates to #9183, #9184, #9187, #9189, #9197, #9193, #9199.

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JSO-6608

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Design-pass addendum (2026-07-28): the view's centerpiece should be the Loop Ring from #9568 — six pipeline nodes (discover → attempt → PR → review → gate → merge) on a ring, real events traveling it as accent pulses, the bottleneck stage rendered with emphasis and a count, clicking a node filtering the timeline below. Same component powers the fleet-aggregate marketing/status rendering (privacy-safe) and a micro variant on repo cards, so requirement 2's loop-health funnel and the ring must present identical figures (the one-source-two-renderings rule). Static fallback with event counts under reduced motion.