fix(mobile): allow starting a task with only an image

apps/mobile/src/features/threads/NewTaskDraftScreen.tsx

@@ -1244,7 +1244,7 @@ export function NewTaskDraftScreen(props: {
     if (
       attachmentBlockReason !== null ||
       !modelSelection ||
-      initialMessageText.length === 0 ||
+      (initialMessageText.length === 0 && draft.attachments.length === 0) ||
       flow.submitting ||
       (workspaceMode === "worktree" && !selectedBranchName)
     ) {
@@ -1397,7 +1397,7 @@ export function NewTaskDraftScreen(props: {
     !modelUnavailable &&
     Boolean(flow.selectedProject) &&
     Boolean(flow.selectedModel) &&
-    flow.prompt.trim().length > 0 &&
+    (flow.prompt.trim().length > 0 || flow.attachments.length > 0) &&
     isIncomingShareReady &&
     !isImportingShare &&
     !flow.submitting &&

apps/mobile/src/features/threads/new-task-flow-provider.tsx

@@ -1105,7 +1105,8 @@ export function NewTaskFlowProvider(props: React.PropsWithChildren) {
           selectedEnvironmentServerConfig,
           draft.modelSelection ?? null,
         ) ?? selectedModel;
-      if (text.length === 0 || !draftModelSelection) {
+      // A shared image or file is a task on its own; text is optional.
+      if ((text.length === 0 && draft.attachments.length === 0) || !draftModelSelection) {
         return null;
       }
       // A saved choice from before the project went no-project must not

apps/mobile/src/state/thread-outbox-model.ts

@@ -247,7 +247,8 @@ export function isQueuedThreadCreationSendable(message: QueuedThreadMessage): bo
   if (!message.creation) {
     return false;
   }
-  if (message.text.trim().length === 0 || message.modelSelection === undefined) {
+  const hasContent = message.text.trim().length > 0 || message.attachments.length > 0;
+  if (!hasContent || message.modelSelection === undefined) {
     return false;
   }
   return message.creation.workspaceMode !== "worktree" || Boolean(message.creation.branch);

apps/mobile/src/state/thread-outbox.test.ts

@@ -1430,6 +1430,26 @@ describe("thread outbox", () => {
       false,
     );
     expect(isQueuedThreadCreationSendable(base)).toBe(false);
+    expect(isQueuedThreadCreationSendable({ ...creationMessage, text: "  " })).toBe(false);
+    expect(
+      isQueuedThreadCreationSendable({
+        ...creationMessage,
+        text: "",
+        attachments: [
+          {
+            id: "image-1",
+            type: "image",
+            name: "photo.png",
+            mimeType: "image/png",
+            sizeBytes: 3,
+            fileUri: "file:///documents/t3-composer-attachments/photo.png",
+            previewUri: "file:///documents/t3-composer-attachments/photo.png",
+            uploadedAttachmentId: "pending-photo-png",
+            uploadEnvironmentId: EnvironmentId.make("environment-1"),
+          },
+        ],
+      }),
+    ).toBe(true);
   });
 
   it("retries transport failures but drops deterministic command failures", () => {