[PM-22992] Send lastKnownRevisionDate with Attachment API calls (#16862)

* Add lastKnownRevisionDate to Attachment methods.

* Address issues raised by Claude PR

* Fix string errors

* Show error to user in event of attachment upload failure

* Improve error handling for missing cipher

* Add unit tests for attachment lastKnownRevisionDate

* Remove generic title from toast errors

* Move lastKnwonRevisionDate to function input

libs/vault/src/cipher-form/components/attachments/cipher-attachments.component.spec.ts

@@ -240,6 +240,49 @@ describe("CipherAttachmentsComponent", () => {
           message: "maxFileSize",
         });
       });
+
+      it("shows error toast with server message when saveAttachmentWithServer fails", async () => {
+        const file = { size: 100 } as File;
+        component.attachmentForm.controls.file.setValue(file);
+
+        const serverError = new Error("Cipher has been modified by another client");
+        saveAttachmentWithServer.mockRejectedValue(serverError);
+
+        await component.submit();
+
+        expect(showToast).toHaveBeenCalledWith({
+          variant: "error",
+          message: "Cipher has been modified by another client",
+        });
+      });
+
+      it("shows error toast with fallback message when error has no message property", async () => {
+        const file = { size: 100 } as File;
+        component.attachmentForm.controls.file.setValue(file);
+
+        saveAttachmentWithServer.mockRejectedValue({ code: "UNKNOWN_ERROR" });
+
+        await component.submit();
+
+        expect(showToast).toHaveBeenCalledWith({
+          variant: "error",
+          message: "unexpectedError",
+        });
+      });
+
+      it("shows error toast with string error message", async () => {
+        const file = { size: 100 } as File;
+        component.attachmentForm.controls.file.setValue(file);
+
+        saveAttachmentWithServer.mockRejectedValue("Network connection failed");
+
+        await component.submit();
+
+        expect(showToast).toHaveBeenCalledWith({
+          variant: "error",
+          message: "Network connection failed",
+        });
+      });
     });
 
     describe("success", () => {

libs/vault/src/cipher-form/components/attachments/cipher-attachments.component.ts

@@ -222,6 +222,19 @@ export class CipherAttachmentsComponent implements OnInit, AfterViewInit {
       this.onUploadSuccess.emit();
     } catch (e) {
       this.logService.error(e);
+
+      // Extract error message from server response, fallback to generic message
+      let errorMessage = this.i18nService.t("unexpectedError");
+      if (typeof e === "string") {
+        errorMessage = e;
+      } else if (e?.message) {
+        errorMessage = e.message;
+      }
+
+      this.toastService.showToast({
+        variant: "error",
+        message: errorMessage,
+      });
     }
   };