shell-redesign V1 polish slice Phase 5.1 P5.1-6: rig overview tab → RigSpecDisplay

V1 founder-walk surfaced ambiguity on the topology rig overview tab:
the tab rendered placeholder text ("Existing rig spec detail page
mounted here in phase five polish") which made it unclear whether
the rig spec surface was intended to mount or whether the tab was
not yet implemented at all.

NEW RigOverviewTab inline component in ScopePages.tsx:
- Mounts existing canonical RigSpecDisplay (the same component that
  renders /specs/rig/$id detail).
- Sources data via useSpecLibrary("rig") + useLibraryReview, matching
  by rig name (per LibraryReview.tsx pattern).
- Loading state: font-mono "Loading rig spec…".
- No-match: EmptyState with hint to author at /specs.
- Multiple-match: EmptyState with disambiguation hint.
- Review-failed: EmptyState graceful degrade.
- Wrapped in 'topology-rig-overview' testid + 'topology-rig-overview-'
  prefix for consistent test selectors.

REMOVED placeholder block ("Existing rig spec detail page mounted
here in phase five polish") and its 'topology-rig-overview-placeholder'
testid — replaced by the live mount.

Verification:
- pnpm -F @openrig/ui exec tsc --noEmit: clean
- (visual walk needed at VM)

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

packages/ui/src/components/topology/ScopePages.tsx

@@ -21,7 +21,9 @@ import { TopologyTerminalView } from "./TopologyTerminalView.js";
 import { SectionHeader } from "../ui/section-header.js";
 import { EmptyState } from "../ui/empty-state.js";
 import { RigGraph } from "../RigGraph.js";
+import { RigSpecDisplay } from "../RigSpecDisplay.js";
 import { useRigSummary } from "../../hooks/useRigSummary.js";
+import { useSpecLibrary, useLibraryReview, type LibraryRigReview } from "../../hooks/useSpecLibrary.js";
 import { LiveNodeDetails } from "../LiveNodeDetails.js";
 import { useTopologyOverlay } from "./topology-overlay-context.js";
 // V1 attempt-3 Phase 5 P5-9: graph view-mode degrades to table on
@@ -173,20 +175,83 @@ export function RigScopePage() {
         </div>
       ) : null}
       {effectiveActive === "terminal" ? <TopologyTerminalView scope="rig" rigId={rigId} /> : null}
-      {active === "overview" ? (
-        <div className="p-6">
-          <EmptyState
-            label="RIG OVERVIEW"
-            description="Existing rig spec / detail page mounted here in Phase 5 polish."
-            variant="card"
-            testId="topology-rig-overview-placeholder"
-          />
-        </div>
-      ) : null}
+      {active === "overview" ? <RigOverviewTab rigId={rigId} rigName={rig?.name ?? null} /> : null}
     </ScopeShell>
   );
 }
 
+/** V1 polish slice Phase 5.1 P5.1-6 — Rig overview tab.
+ *
+ *  Founder direction at V1 founder-walk:
+ *  > "Topology page, there's an overview tab that says 'rig overview
+ *  > existing rig spec detail page mounted here in phase five polish.'"
+ *
+ *  Mounts the existing canonical RigSpecDisplay component (from
+ *  /specs/rig/$id) sourced via useSpecLibrary("rig") + useLibraryReview.
+ *  Matches the rig name against the library entries (per
+ *  LibraryReview.tsx pattern) and renders the spec detail.
+ */
+function RigOverviewTab({ rigId, rigName }: { rigId: string; rigName: string | null }) {
+  const { data: entries = [], isLoading: entriesLoading } = useSpecLibrary("rig");
+  // Match by rig name when available; some rigs may have one library
+  // entry per name (operator-authored rig spec).
+  const matches = rigName ? entries.filter((e) => e.name === rigName) : [];
+  const entryId = matches.length === 1 ? matches[0]!.id : null;
+  const { data: review, isLoading: reviewLoading } = useLibraryReview(entryId);
+
+  if (entriesLoading || reviewLoading) {
+    return (
+      <div className="p-6">
+        <div className="font-mono text-[10px] text-stone-400">Loading rig spec…</div>
+      </div>
+    );
+  }
+  if (matches.length === 0) {
+    return (
+      <div className="p-6">
+        <EmptyState
+          label="NO RIG SPEC"
+          description={`No rig spec entry found for "${rigName ?? rigId}". Author one via /specs.`}
+          variant="card"
+          testId="topology-rig-overview-no-spec"
+        />
+      </div>
+    );
+  }
+  if (matches.length > 1) {
+    return (
+      <div className="p-6">
+        <EmptyState
+          label="AMBIGUOUS RIG SPEC"
+          description={`${matches.length} rig spec entries match "${rigName ?? rigId}". Disambiguate at /specs.`}
+          variant="card"
+        />
+      </div>
+    );
+  }
+  if (!review || review.kind !== "rig") {
+    return (
+      <div className="p-6">
+        <EmptyState
+          label="RIG SPEC UNAVAILABLE"
+          description="Rig spec failed to load."
+          variant="card"
+        />
+      </div>
+    );
+  }
+  const rigReview = review as LibraryRigReview;
+  return (
+    <div className="px-6 pb-6" data-testid="topology-rig-overview">
+      <RigSpecDisplay
+        review={rigReview}
+        yaml={rigReview.raw}
+        testIdPrefix="topology-rig-overview-"
+      />
+    </div>
+  );
+}
+
 export function PodScopePage() {
   const { rigId, podName } = useParams({ from: "/topology/pod/$rigId/$podName" });
   const [active, setActive] = useState<TopologyRigPodScopeTab>("table");