test: cross-product Instant Preview's evidence-key pair with the adapter's

`evidence-key-agreement.test.ts` cross-products 144 adversarial combinations
across the mock adapter's gate and descriptor resolver, `validateWorkingCopy`
and the shared pixel resolver -- but omitted `instant-preview.tsx`'s own gate
and descriptor resolver. That pair is byte-parallel to the adapter's (it
lives in `presentation/`, which may not import `adapters/`, so it carries its
own copy of the legacy-key predicate) and it is exactly the pair three earlier
fix rounds regressed.

`instant-preview.tsx` now exports the two expressions it already used, so the
test drives the production code rather than rebuilding it. Added assertions:
gate agreement in both array orders, descriptor equality with the adapter's,
pixel/descriptor agreement, and order independence. The one sanctioned
divergence -- the legacy static key's `assetId`, a fixed literal here versus a
registry-derived one there -- is pinned to that case rather than ignored.

Mutation-checked: breaking the legacy predicate reports 96 of 144 combinations
disagreeing, breaking the legacy descriptor path reports 64 of 144.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/features/tech-log/presentation/studio/components/instant-preview.tsx

@@ -23,17 +23,29 @@ type PublicRenderModel = components["schemas"]["PublicRenderModel"];
  * catalog carries a fixture `EVIDENCE` row for it, but no `Asset` record
  * backs it, so `assets` never resolves it.
  */
-function isLegacyStaticEvidenceKey(key: string): boolean {
+export function isLegacyStaticEvidenceKey(key: string): boolean {
   return key === "fetch-strategy-boundary";
 }
 
+/**
+ * Instant Preview's evidence-key gate. Exported so
+ * `tests/features/tech-log/evidence-key-agreement.test.ts` cross-products
+ * *this* expression against the mock adapter's byte-parallel pair rather than
+ * rebuilding it -- three earlier fix rounds regressed exactly this pair, each
+ * time by writing a second expression that agreed only on the examples that
+ * round happened to use.
+ */
+export function instantPreviewEvidenceKeyGate(assets: readonly Asset[]) {
+  return supportsResolvableEvidenceKey(assets, isLegacyStaticEvidenceKey);
+}
+
 /**
  * Total -- never throws. Resolves through `findResolvableAsset`, the same
  * function this file's key gate and `createAssetCatalogResolver` (which
  * supplies the pixels) use, so the descriptor attached to a block and the
  * image rendered for it always come from one Asset.
  */
-function resolveAssetDescriptor(assets: readonly Asset[]) {
+export function resolveInstantPreviewAssetDescriptor(assets: readonly Asset[]) {
   return (key: string): ResolvedAsset => {
     const asset = findResolvableAsset(assets, key);
     if (asset) {
@@ -96,9 +108,9 @@ export function InstantPreview({
         // key. A key this rejects fails the projection, and the error panel
         // below names it -- the same key `validateDocument` reports
         // `EVIDENCE_UNSUPPORTED` for.
-        supportsResolvableEvidenceKey(assets, isLegacyStaticEvidenceKey),
+        instantPreviewEvidenceKeyGate(assets),
       ),
-      resolveAssetDescriptor(assets),
+      resolveInstantPreviewAssetDescriptor(assets),
     );
   } catch (error) {
     issues = error instanceof ContentFormatError