feat: Download the uploaded files (#31068)

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api/agent-notes/tests/unit_tests/controllers/console/datasets/test_datasets_document_download.py.md

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+## Purpose
+
+Unit tests for the console dataset document download endpoint:
+
+- `GET /datasets/<dataset_id>/documents/<document_id>/download`
+
+## Testing approach
+
+- Uses `Flask.test_request_context()` and calls the `Resource.get(...)` method directly.
+- Monkeypatches console decorators (`login_required`, `setup_required`, rate limit) to no-ops to keep the test focused.
+- Mocks:
+  - `DatasetService.get_dataset` / `check_dataset_permission`
+  - `DocumentService.get_document` for single-file download tests
+  - `DocumentService.get_documents_by_ids` + `FileService.get_upload_files_by_ids` for ZIP download tests
+  - `FileService.get_upload_files_by_ids` for `UploadFile` lookups in single-file tests
+  - `services.dataset_service.file_helpers.get_signed_file_url` to return a deterministic URL
+- Document mocks include `id` fields so batch lookups can map documents by id.
+
+## Covered cases
+
+- Success returns `{ "url": "<signed>" }` for upload-file documents.
+- 404 when document is not `upload_file`.
+- 404 when `upload_file_id` is missing.
+- 404 when referenced `UploadFile` row does not exist.
+- 403 when document tenant does not match current tenant.
+- Batch ZIP download returns `application/zip` for upload-file documents.
+- Batch ZIP download rejects non-upload-file documents.
+- Batch ZIP download uses a random `.zip` attachment name (`download_name`), so tests only assert the suffix.

api/agent-notes/tests/unit_tests/services/test_file_service_zip_and_lookup.py.md

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+## Purpose
+
+Unit tests for `api/services/file_service.py` helper methods that are not covered by higher-level controller tests.
+
+## What’s covered
+
+- `FileService.build_upload_files_zip_tempfile(...)`
+  - ZIP entry name sanitization (no directory components / traversal)
+  - name deduplication while preserving extensions
+  - writing streamed bytes from `storage.load(...)` into ZIP entries
+  - yields a tempfile path so callers can open/stream the ZIP without holding a live file handle
+- `FileService.get_upload_files_by_ids(...)`
+  - returns `{}` for empty id lists
+  - returns an id-keyed mapping for non-empty lists
+
+## Notes
+
+- These tests intentionally stub `storage.load` and `db.session.scalars(...).all()` to avoid needing a real DB/storage.