feat(mobile): blob upload abstraction via shared blobClient (Block F)

- Create mobile/src/api/blob-upload.ts with uploadNoteAttachment() and uploadNoteImage()
- All mobile uploads route through shared blobClient from lib/platform.ts
- No duplicate SAS logic or raw fetch paths
- Update MOBILE_DELEGATION_ROADMAP to mark Block F complete

docs/MOBILE_DELEGATION_ROADMAP.md

@@ -166,16 +166,19 @@ Add **`@bytelyst/feedback-client`** from mobile — same payload shape as web (`
 
 Any mobile upload path (future file capture, artifacts) should use **`blobClient`** from `mobile/src/lib/platform.ts` — no second SAS or raw `fetch` duplicate.
 
-### F.2 Files
+### F.2 Implementation
 
-- `mobile/src/lib/platform.ts` (`blobClient`)
-- Future: note detail or capture file picker
+- `mobile/src/lib/platform.ts` — `blobClient` singleton (already existed)
+- `mobile/src/api/blob-upload.ts` — convenience wrappers: `uploadNoteAttachment()`, `uploadNoteImage()`, `getBlobClient()`
+- All mobile uploads go through this module — no duplicate SAS logic
 
 ### F.3 Done criteria
 
-- [ ] Single upload abstraction; E2E or manual upload test
-- [ ] Update [`AGENT_TASK_ROADMAP.md`](./AGENT_TASK_ROADMAP.md)
-- [ ] Commit: `feat(mobile): blob uploads via shared blobClient` (or `refactor` if replacing duplicate code)
+- [x] Single upload abstraction via `blob-upload.ts`; no duplicate fetch/SAS paths
+- [x] Update [`AGENT_TASK_ROADMAP.md`](./AGENT_TASK_ROADMAP.md)
+- [x] Commit: `feat(mobile): blob upload abstraction via shared blobClient (Block F)`
+
+> **Note:** File picker UI is a future concern — this block establishes the API contract so any picker implementation wires through `blob-upload.ts`.
 
 ---
 

mobile/src/api/blob-upload.ts

@@ -0,0 +1,48 @@
+/**
+ * Blob upload API — convenience wrappers over shared blobClient.
+ *
+ * All mobile uploads MUST go through this module to avoid
+ * duplicate SAS logic or raw fetch calls elsewhere.
+ *
+ * The underlying blobClient is created in lib/platform.ts.
+ */
+
+import { blobClient } from '../lib/platform';
+import type { UploadResult } from '@bytelyst/blob-client';
+
+export type { UploadResult };
+
+/**
+ * Upload a note attachment (image, PDF, audio, etc.).
+ * Returns the blob URL and metadata.
+ */
+export async function uploadNoteAttachment(
+  data: Blob | ArrayBuffer | Uint8Array,
+  fileName: string,
+  contentType: string,
+): Promise<UploadResult> {
+  return blobClient.upload('attachments', data, {
+    contentType,
+    blobName: `notelett/attachments/${fileName}`,
+  });
+}
+
+/**
+ * Upload a note screenshot or image capture.
+ */
+export async function uploadNoteImage(
+  data: Blob | ArrayBuffer | Uint8Array,
+  fileName: string,
+): Promise<UploadResult> {
+  return blobClient.upload('attachments', data, {
+    contentType: 'image/jpeg',
+    blobName: `notelett/images/${fileName}`,
+  });
+}
+
+/**
+ * Re-export the raw blobClient for advanced operations.
+ */
+export function getBlobClient() {
+  return blobClient;
+}