feat(app): store assistant image previews as assets

packages/app/src/desktop/attachments/desktop-attachment-store.test.ts

@@ -86,6 +86,33 @@ describe("desktop attachment store", () => {
     });
   });
 
+  it("saves raw base64 sources via desktop filesystem writes", async () => {
+    const store = createDesktopAttachmentStore();
+    const attachment = await store.save({
+      id: "att_base64",
+      mimeType: "image/png",
+      fileName: "inline.png",
+      source: {
+        kind: "base64",
+        base64: "AAECAw==",
+      },
+    });
+
+    expect(writeDesktopAttachmentBase64Mock).toHaveBeenCalledWith({
+      attachmentId: "att_base64",
+      base64: "AAECAw==",
+      extension: ".png",
+    });
+    expect(attachment).toMatchObject({
+      id: "att_base64",
+      mimeType: "image/png",
+      storageType: "desktop-file",
+      storageKey: "/managed/att_2.png",
+      fileName: "inline.png",
+      byteSize: 4,
+    });
+  });
+
   it("delegates encode/preview/delete/gc to desktop command path", async () => {
     const store = createDesktopAttachmentStore();
     const attachment = {

packages/app/src/desktop/attachments/desktop-attachment-store.ts

@@ -166,6 +166,16 @@ export function createDesktopAttachmentStore(): AttachmentStore {
         });
       }
 
+      if (input.source.kind === "base64") {
+        const mimeType = normalizeMimeType(input.mimeType);
+        return await saveDesktopAttachmentFromBase64({
+          id,
+          base64: input.source.base64,
+          mimeType,
+          fileName,
+        });
+      }
+
       const mimeType = normalizeMimeType(input.mimeType ?? input.source.blob.type);
       const base64 = await blobToBase64(input.source.blob);
       return await saveDesktopAttachmentFromBase64({