fix: keep user turn media fields aligned

src/sessions/user-turn-transcript.test.ts

@@ -51,5 +51,19 @@ describe("user turn transcript persistence", () => {
         MediaTypes: ["document", "application/octet-stream"],
       });
     });
+
+    it("keeps media paths and types aligned when incomplete entries are skipped", () => {
+      expect(
+        buildPersistedUserTurnMediaFields([
+          { contentType: "image/png" },
+          { path: "/tmp/b.jpg", contentType: "image/jpeg" },
+        ]),
+      ).toEqual({
+        MediaPath: "/tmp/b.jpg",
+        MediaPaths: ["/tmp/b.jpg"],
+        MediaType: "image/jpeg",
+        MediaTypes: ["image/jpeg"],
+      });
+    });
   });
 });

src/sessions/user-turn-transcript.ts

@@ -25,19 +25,34 @@ function mediaTypeForTranscript(media: PersistedUserTurnMediaInput): string {
   );
 }
 
+function normalizeMediaEntryForTranscript(media: PersistedUserTurnMediaInput):
+  | {
+      path: string;
+      type: string;
+    }
+  | undefined {
+  const path = normalizeOptionalText(media.path) ?? normalizeOptionalText(media.url);
+  if (!path) {
+    return undefined;
+  }
+  return {
+    path,
+    type: mediaTypeForTranscript(media),
+  };
+}
+
 export function buildPersistedUserTurnMediaFields(
   media: readonly PersistedUserTurnMediaInput[] | null | undefined,
 ): PersistedUserTurnMediaFields {
   const entries = Array.isArray(media) ? media : [];
-  const paths = entries
-    .map((entry) => normalizeOptionalText(entry.path) ?? normalizeOptionalText(entry.url))
-    .filter((path): path is string => Boolean(path));
+  const normalized = entries
+    .map(normalizeMediaEntryForTranscript)
+    .filter((entry): entry is { path: string; type: string } => entry !== undefined);
+  const paths = normalized.map((entry) => entry.path);
   if (paths.length === 0) {
     return {};
   }
-  const types = entries
-    .map((entry, index) => (paths[index] ? mediaTypeForTranscript(entry) : undefined))
-    .filter((type): type is string => Boolean(type));
+  const types = normalized.map((entry) => entry.type);
   return {
     MediaPath: paths[0],
     MediaPaths: paths,