feat: add layered render recovery boundaries

src/application/use-cases/decide-chunk-recovery.js

@@ -0,0 +1,34 @@
+const RECOVERABLE_KINDS = new Set(["CHUNK_LOAD_FAILURE", "DEPLOY_MISMATCH"]);
+
+/**
+ * @param {{
+ *   failureKind: string,
+ *   manifestLoaded: boolean,
+ *   currentBuildId: string,
+ *   activeReleaseId: string,
+ *   storage: import("../ports/storage-port.js").StoragePort
+ * }} input
+ */
+export function decideChunkRecovery(input) {
+  if (!RECOVERABLE_KINDS.has(input.failureKind)) {
+    return { action: "support", reason: "not-recoverable" };
+  }
+  if (!input.manifestLoaded) {
+    return { action: "support", reason: "manifest-unavailable" };
+  }
+  if (input.activeReleaseId === input.currentBuildId) {
+    return { action: "support", reason: "same-release" };
+  }
+
+  const releasePair = `${input.currentBuildId}->${input.activeReleaseId}`;
+  const guard = input.storage.read("CHUNK_RELOAD_GUARD");
+  if (!guard.ok || guard.value === releasePair) {
+    return { action: "support", reason: "reload-already-attempted" };
+  }
+
+  const recorded = input.storage.write("CHUNK_RELOAD_GUARD", releasePair);
+  if (!recorded.ok) {
+    return { action: "support", reason: "guard-write-failed" };
+  }
+  return { action: "reload-once", releasePair };
+}