feat: B3 uit voor veilige archive-downloads - cancel knop toegevoegd

webui/backend/app/api/routes_files.py

@@ -4,7 +4,7 @@ from fastapi import APIRouter, Depends, File, Form, Query, Request, UploadFile
 from fastapi.responses import StreamingResponse
 from starlette.background import BackgroundTask
 
-from backend.app.api.schemas import ArchivePrepareRequest, DeleteRequest, DeleteResponse, FileInfoResponse, MkdirRequest, MkdirResponse, RenameRequest, RenameResponse, SaveRequest, SaveResponse, TaskCreateResponse, UploadResponse, ViewResponse
+from backend.app.api.schemas import ArchivePrepareRequest, DeleteRequest, DeleteResponse, FileInfoResponse, MkdirRequest, MkdirResponse, RenameRequest, RenameResponse, SaveRequest, SaveResponse, TaskCreateResponse, TaskDetailResponse, UploadResponse, ViewResponse
 from backend.app.dependencies import get_archive_download_task_service, get_file_ops_service
 from backend.app.services.archive_download_task_service import ArchiveDownloadTaskService
 from backend.app.services.file_ops_service import FileOpsService
@@ -100,6 +100,14 @@ async def archive_download(
     )
 
 
+@router.post("/download/archive/{task_id}/cancel", response_model=TaskDetailResponse)
+async def archive_cancel(
+    task_id: str,
+    service: ArchiveDownloadTaskService = Depends(get_archive_download_task_service),
+) -> TaskDetailResponse:
+    return TaskDetailResponse(**service.cancel_archive_prepare_task(task_id=task_id))
+
+
 @router.get("/video")
 async def video(
     path: str,

webui/backend/app/db/history_repository.py

@@ -6,7 +6,7 @@ from contextlib import contextmanager
 from datetime import datetime, timezone
 from pathlib import Path
 
-VALID_HISTORY_STATUSES = {"queued", "completed", "failed", "requested", "ready", "preflight_failed"}
+VALID_HISTORY_STATUSES = {"queued", "completed", "failed", "requested", "ready", "preflight_failed", "cancelled"}
 VALID_HISTORY_OPERATIONS = {"mkdir", "rename", "delete", "copy", "move", "upload", "download"}
 
 

webui/backend/app/db/task_repository.py

@@ -6,7 +6,7 @@ from contextlib import contextmanager
 from datetime import datetime, timezone
 from pathlib import Path
 
-VALID_STATUSES = {"queued", "running", "completed", "failed", "requested", "preparing", "ready"}
+VALID_STATUSES = {"queued", "running", "completed", "failed", "requested", "preparing", "ready", "cancelled"}
 VALID_OPERATIONS = {"copy", "move", "download"}
 TASK_MIGRATION_COLUMNS: dict[str, str] = {
     "operation": "TEXT NOT NULL DEFAULT 'copy'",
@@ -160,17 +160,18 @@ class TaskRepository:
         done_items: int | None = None,
         total_items: int | None = None,
         current_item: str | None = None,
-    ) -> None:
+    ) -> bool:
         started_at = self._now_iso()
         with self._connection() as conn:
-            conn.execute(
+            cursor = conn.execute(
                 """
                 UPDATE tasks
                 SET status = ?, started_at = COALESCE(started_at, ?), done_items = ?, total_items = ?, current_item = ?
-                WHERE id = ?
+                WHERE id = ? AND status = ?
                 """,
-                ("preparing", started_at, done_items, total_items, current_item, task_id),
+                ("preparing", started_at, done_items, total_items, current_item, task_id, "requested"),
             )
+        return cursor.rowcount > 0
 
     def update_progress(
         self,
@@ -215,17 +216,18 @@ class TaskRepository:
         task_id: str,
         done_items: int | None = None,
         total_items: int | None = None,
-    ) -> None:
+    ) -> bool:
         finished_at = self._now_iso()
         with self._connection() as conn:
-            conn.execute(
+            cursor = conn.execute(
                 """
                 UPDATE tasks
                 SET status = ?, finished_at = ?, done_items = ?, total_items = ?, current_item = NULL
-                WHERE id = ?
+                WHERE id = ? AND status = ?
                 """,
-                ("ready", finished_at, done_items, total_items, task_id),
+                ("ready", finished_at, done_items, total_items, task_id, "preparing"),
             )
+        return cursor.rowcount > 0
 
     def mark_failed(
         self,
@@ -260,6 +262,54 @@ class TaskRepository:
                 ),
             )
 
+    def mark_failed_if_not_cancelled(
+        self,
+        task_id: str,
+        error_code: str,
+        error_message: str,
+        failed_item: str | None,
+        done_bytes: int | None,
+        total_bytes: int | None,
+        done_items: int | None = None,
+        total_items: int | None = None,
+    ) -> bool:
+        finished_at = self._now_iso()
+        with self._connection() as conn:
+            cursor = conn.execute(
+                """
+                UPDATE tasks
+                SET status = ?, finished_at = ?, error_code = ?, error_message = ?, failed_item = ?, done_bytes = ?, total_bytes = ?, done_items = ?, total_items = ?, current_item = NULL
+                WHERE id = ? AND status != ?
+                """,
+                (
+                    "failed",
+                    finished_at,
+                    error_code,
+                    error_message,
+                    failed_item,
+                    done_bytes,
+                    total_bytes,
+                    done_items,
+                    total_items,
+                    task_id,
+                    "cancelled",
+                ),
+            )
+        return cursor.rowcount > 0
+
+    def mark_cancelled(self, task_id: str) -> bool:
+        finished_at = self._now_iso()
+        with self._connection() as conn:
+            cursor = conn.execute(
+                """
+                UPDATE tasks
+                SET status = ?, finished_at = ?, current_item = NULL
+                WHERE id = ? AND status IN (?, ?)
+                """,
+                ("cancelled", finished_at, task_id, "requested", "preparing"),
+            )
+        return cursor.rowcount > 0
+
     def _ensure_schema(self) -> None:
         db_path = Path(self._db_path)
         if db_path.parent and str(db_path.parent) not in {"", "."}:

webui/backend/app/services/archive_download_task_service.py

@@ -17,6 +17,10 @@ from backend.app.tasks_runner import TaskRunner
 ARCHIVE_DOWNLOAD_TTL_SECONDS = 30 * 60
 
 
+class ArchivePrepareCancelled(Exception):
+    pass
+
+
 class ArchiveDownloadTaskService:
     def __init__(
         self,
@@ -103,6 +107,13 @@ class ArchiveDownloadTaskService:
                 status_code=400,
                 details={"task_id": task_id},
             )
+        if task["status"] == "cancelled":
+            raise AppError(
+                code="download_cancelled",
+                message="Archive download was cancelled",
+                status_code=409,
+                details={"task_id": task_id},
+            )
         if task["status"] != "ready":
             raise AppError(
                 code="download_not_ready",
@@ -147,6 +158,58 @@ class ArchiveDownloadTaskService:
             "content_type": "application/zip",
         }
 
+    def cancel_archive_prepare_task(self, task_id: str) -> dict:
+        self.sweep_artifacts()
+        task = self._repository.get_task(task_id)
+        if not task:
+            raise AppError(
+                code="task_not_found",
+                message="Task was not found",
+                status_code=404,
+                details={"task_id": task_id},
+            )
+        if task["operation"] != "download":
+            raise AppError(
+                code="invalid_request",
+                message="Task is not an archive download",
+                status_code=400,
+                details={"task_id": task_id},
+            )
+        if task["status"] == "ready":
+            raise AppError(
+                code="download_not_cancellable",
+                message="Archive download is already ready",
+                status_code=409,
+                details={"task_id": task_id, "status": task["status"]},
+            )
+        if task["status"] in {"failed", "cancelled"}:
+            raise AppError(
+                code="download_not_cancellable",
+                message="Archive download cannot be cancelled",
+                status_code=409,
+                details={"task_id": task_id, "status": task["status"]},
+            )
+        if not self._repository.mark_cancelled(task_id):
+            current = self._repository.get_task(task_id)
+            current_status = current["status"] if current else task["status"]
+            raise AppError(
+                code="download_not_cancellable",
+                message="Archive download cannot be cancelled",
+                status_code=409,
+                details={"task_id": task_id, "status": current_status},
+            )
+        self._cleanup_task_artifacts(task_id)
+        self._update_history_cancelled(task_id)
+        cancelled_task = self._repository.get_task(task_id)
+        if not cancelled_task:
+            raise AppError(
+                code="task_not_found",
+                message="Task was not found",
+                status_code=404,
+                details={"task_id": task_id},
+            )
+        return cancelled_task
+
     def sweep_artifacts(self) -> None:
         self._artifact_root.mkdir(parents=True, exist_ok=True)
         referenced_paths: set[Path] = set()
@@ -177,37 +240,59 @@ class ArchiveDownloadTaskService:
         total_items = len(target_paths)
 
         try:
-            self._repository.mark_preparing(
+            self._raise_if_cancelled(task_id)
+            if not self._repository.mark_preparing(
                 task_id=task_id,
                 done_items=0,
                 total_items=total_items,
                 current_item=target_paths[0] if target_paths else None,
-            )
+            ):
+                self._raise_if_cancelled(task_id)
+                return
             resolved_targets = [self._path_guard.resolve_existing_path(path) for path in target_paths]
+            self._raise_if_cancelled(task_id)
             self._file_ops_service._validate_zip_download_archive_names(resolved_targets)
             self._file_ops_service._run_zip_download_preflight(resolved_targets)
+            self._raise_if_cancelled(task_id)
 
             with zipfile.ZipFile(partial_path, "w", compression=zipfile.ZIP_DEFLATED) as archive:
-                for resolved_target in resolved_targets:
+                for index, resolved_target in enumerate(resolved_targets):
-                    self._file_ops_service._write_download_target_to_zip(archive, resolved_target)
+                    self._raise_if_cancelled(task_id)
+                    self._repository.update_progress(
+                        task_id=task_id,
+                        done_items=index,
+                        total_items=total_items,
+                        current_item=resolved_target.relative,
+                    )
+                    self._file_ops_service._write_download_target_to_zip(
+                        archive,
+                        resolved_target,
+                        on_each_item=lambda: self._raise_if_cancelled(task_id),
+                    )
 
+            self._raise_if_cancelled(task_id)
             os.replace(partial_path, final_path)
+            self._raise_if_cancelled(task_id)
             self._repository.upsert_artifact(
                 task_id=task_id,
                 file_path=str(final_path),
                 file_name=archive_name,
                 expires_at=self._expires_at_iso(),
             )
-            self._repository.mark_ready(
+            if not self._repository.mark_ready(
                 task_id=task_id,
                 done_items=total_items,
                 total_items=total_items,
-            )
+            ):
+                self._cleanup_task_artifacts(task_id)
+                self._raise_if_cancelled(task_id)
+                return
             self._update_history_ready(task_id)
+        except ArchivePrepareCancelled:
+            self._cleanup_task_artifacts(task_id)
         except AppError as exc:
-            self._delete_artifact_record_and_file(task_id, str(partial_path))
+            self._cleanup_task_artifacts(task_id)
-            self._delete_artifact_record_and_file(task_id, str(final_path))
+            if self._repository.mark_failed_if_not_cancelled(
-            self._repository.mark_failed(
                 task_id=task_id,
                 error_code=exc.code,
                 error_message=exc.message,
@@ -216,12 +301,11 @@ class ArchiveDownloadTaskService:
                 total_bytes=None,
                 done_items=0,
                 total_items=total_items,
-            )
+            ):
                 self._update_history_failed(task_id, exc.code, exc.message)
         except OSError as exc:
-            self._delete_artifact_record_and_file(task_id, str(partial_path))
+            self._cleanup_task_artifacts(task_id)
-            self._delete_artifact_record_and_file(task_id, str(final_path))
+            if self._repository.mark_failed_if_not_cancelled(
-            self._repository.mark_failed(
                 task_id=task_id,
                 error_code="io_error",
                 error_message=str(exc),
@@ -230,9 +314,13 @@ class ArchiveDownloadTaskService:
                 total_bytes=None,
                 done_items=0,
                 total_items=total_items,
-            )
+            ):
                 self._update_history_failed(task_id, "io_error", str(exc))
 
+    def _cleanup_task_artifacts(self, task_id: str) -> None:
+        self._delete_artifact_record_and_file(task_id, str(self._artifact_root / f"{task_id}.partial.zip"))
+        self._delete_artifact_record_and_file(task_id, str(self._artifact_root / f"{task_id}.zip"))
+
     def _delete_artifact_record_and_file(self, task_id: str, file_path: str) -> None:
         self._repository.delete_artifact(task_id)
         path = Path(file_path)
@@ -254,6 +342,10 @@ class ArchiveDownloadTaskService:
                 error_message=error_message,
             )
 
+    def _update_history_cancelled(self, task_id: str) -> None:
+        if self._history_repository:
+            self._history_repository.update_entry(entry_id=task_id, status="cancelled")
+
     def _record_history(self, **kwargs) -> None:
         if self._history_repository:
             self._history_repository.create_entry(**kwargs)
@@ -264,3 +356,8 @@ class ArchiveDownloadTaskService:
     @staticmethod
     def _is_expired(expires_at: str) -> bool:
         return datetime.now(timezone.utc) >= datetime.fromisoformat(expires_at.replace("Z", "+00:00"))
+
+    def _raise_if_cancelled(self, task_id: str) -> None:
+        task = self._repository.get_task(task_id)
+        if task and task["status"] == "cancelled":
+            raise ArchivePrepareCancelled()

webui/backend/app/services/file_ops_service.py

@@ -1005,14 +1005,18 @@ class FileOpsService:
             details={"reason": reason, **details},
         )
 
-    def _write_download_target_to_zip(self, archive: zipfile.ZipFile, resolved_target) -> None:
+    def _write_download_target_to_zip(self, archive: zipfile.ZipFile, resolved_target, on_each_item=None) -> None:
         root_name = resolved_target.absolute.name
         if resolved_target.absolute.is_file():
+            if on_each_item:
+                on_each_item()
             archive.write(resolved_target.absolute, arcname=root_name)
             return
 
         archive.writestr(f"{root_name}/", b"")
         for child in sorted(resolved_target.absolute.rglob("*")):
+            if on_each_item:
+                on_each_item()
             arcname = f"{root_name}/{child.relative_to(resolved_target.absolute).as_posix()}"
             if child.is_dir():
                 archive.writestr(f"{arcname}/", b"")

webui/backend/tests/golden/test_api_download_golden.py

@@ -37,11 +37,26 @@ class BlockingArchiveFileOpsService(FileOpsService):
 
 
 class FailingArchiveFileOpsService(FileOpsService):
-    def _write_download_target_to_zip(self, archive: zipfile.ZipFile, resolved_target) -> None:
+    def _write_download_target_to_zip(self, archive: zipfile.ZipFile, resolved_target, on_each_item=None) -> None:
         archive.writestr("partial.txt", b"partial")
         raise OSError("forced archive failure")
 
 
+class BlockingArchiveBuildFileOpsService(FileOpsService):
+    def __init__(self, *args, entered: threading.Event, release: threading.Event, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._entered = entered
+        self._release = release
+
+    def _write_download_target_to_zip(self, archive: zipfile.ZipFile, resolved_target, on_each_item=None) -> None:
+        archive.writestr("partial.txt", b"partial")
+        self._entered.set()
+        self._release.wait(timeout=2.0)
+        if on_each_item:
+            on_each_item()
+        super()._write_download_target_to_zip(archive, resolved_target, on_each_item=on_each_item)
+
+
 class DownloadApiGoldenTest(unittest.TestCase):
     def setUp(self) -> None:
         self.temp_dir = tempfile.TemporaryDirectory()
@@ -221,6 +236,71 @@ class DownloadApiGoldenTest(unittest.TestCase):
         self.assertEqual(task["error_code"], "io_error")
         self.assertEqual(list(self.artifact_root.glob("*")), [])
 
+    def test_archive_cancel_during_preparing_sets_cancelled_and_removes_partial_artifact(self) -> None:
+        entered = threading.Event()
+        release = threading.Event()
+        file_ops_service = BlockingArchiveBuildFileOpsService(
+            path_guard=self.path_guard,
+            filesystem=self.filesystem,
+            history_repository=self.history_repo,
+            zip_download_preflight_limits=ZipDownloadPreflightLimits(),
+            entered=entered,
+            release=release,
+        )
+        self._override_services(file_ops_service=file_ops_service)
+        (self.root / "docs").mkdir()
+        (self.root / "docs" / "a.txt").write_text("a", encoding="utf-8")
+
+        created = self._request("POST", "/api/files/download/archive-prepare", {"paths": ["storage1/docs"]})
+
+        self.assertEqual(created.status_code, 202)
+        self.assertTrue(entered.wait(timeout=2.0))
+        response = self._request("POST", f"/api/files/download/archive/{created.json()['task_id']}/cancel")
+        release.set()
+        task = self._wait_for_task_status(created.json()["task_id"], {"cancelled"})
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json()["status"], "cancelled")
+        self.assertEqual(task["status"], "cancelled")
+        self.assertEqual(list(self.artifact_root.glob("*")), [])
+
+    def test_archive_retrieval_for_cancelled_task_rejected(self) -> None:
+        entered = threading.Event()
+        release = threading.Event()
+        file_ops_service = BlockingArchiveBuildFileOpsService(
+            path_guard=self.path_guard,
+            filesystem=self.filesystem,
+            history_repository=self.history_repo,
+            zip_download_preflight_limits=ZipDownloadPreflightLimits(),
+            entered=entered,
+            release=release,
+        )
+        self._override_services(file_ops_service=file_ops_service)
+        (self.root / "docs").mkdir()
+        (self.root / "docs" / "a.txt").write_text("a", encoding="utf-8")
+
+        created = self._request("POST", "/api/files/download/archive-prepare", {"paths": ["storage1/docs"]})
+
+        self.assertTrue(entered.wait(timeout=2.0))
+        cancel_response = self._request("POST", f"/api/files/download/archive/{created.json()['task_id']}/cancel")
+        release.set()
+        response = self._request("GET", f"/api/files/download/archive/{created.json()['task_id']}")
+
+        self.assertEqual(cancel_response.status_code, 200)
+        self.assertEqual(response.status_code, 409)
+        self.assertEqual(response.json()["error"]["code"], "download_cancelled")
+
+    def test_archive_cancel_after_ready_rejected(self) -> None:
+        (self.root / "docs").mkdir()
+        (self.root / "docs" / "a.txt").write_text("a", encoding="utf-8")
+        created = self._request("POST", "/api/files/download/archive-prepare", {"paths": ["storage1/docs"]})
+        task = self._wait_for_task_status(created.json()["task_id"], {"ready"})
+
+        response = self._request("POST", f"/api/files/download/archive/{task['id']}/cancel")
+
+        self.assertEqual(response.status_code, 409)
+        self.assertEqual(response.json()["error"]["code"], "download_not_cancellable")
+
     def test_expired_artifact_rejected_and_removed(self) -> None:
         (self.root / "docs").mkdir()
         (self.root / "docs" / "a.txt").write_text("a", encoding="utf-8")

webui/backend/tests/golden/test_api_history_golden.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 import asyncio
 import sys
 import tempfile
+import threading
 import time
 import unittest
 from pathlib import Path
@@ -11,12 +12,13 @@ import httpx
 
 sys.path.insert(0, str(Path(__file__).resolve().parents[3]))
 
-from backend.app.dependencies import get_copy_task_service, get_file_ops_service, get_history_service, get_move_task_service, get_task_service
+from backend.app.dependencies import get_archive_download_task_service, get_copy_task_service, get_file_ops_service, get_history_service, get_move_task_service, get_task_service
 from backend.app.db.history_repository import HistoryRepository
 from backend.app.db.task_repository import TaskRepository
 from backend.app.fs.filesystem_adapter import FilesystemAdapter
 from backend.app.main import app
 from backend.app.security.path_guard import PathGuard
+from backend.app.services.archive_download_task_service import ArchiveDownloadTaskService
 from backend.app.services.copy_task_service import CopyTaskService
 from backend.app.services.file_ops_service import FileOpsService
 from backend.app.services.history_service import HistoryService
@@ -30,6 +32,21 @@ class FailingCopyFilesystemAdapter(FilesystemAdapter):
         raise OSError('forced copy failure')
 
 
+class BlockingArchiveBuildFileOpsService(FileOpsService):
+    def __init__(self, *args, entered: threading.Event, release: threading.Event, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._entered = entered
+        self._release = release
+
+    def _write_download_target_to_zip(self, archive, resolved_target, on_each_item=None) -> None:
+        archive.writestr("partial.txt", b"partial")
+        self._entered.set()
+        self._release.wait(timeout=2.0)
+        if on_each_item:
+            on_each_item()
+        super()._write_download_target_to_zip(archive, resolved_target, on_each_item=on_each_item)
+
+
 class HistoryApiGoldenTest(unittest.TestCase):
     def setUp(self) -> None:
         self.temp_dir = tempfile.TemporaryDirectory()
@@ -38,6 +55,7 @@ class HistoryApiGoldenTest(unittest.TestCase):
         self.root1.mkdir(parents=True, exist_ok=True)
         self.root2.mkdir(parents=True, exist_ok=True)
         db_path = str(Path(self.temp_dir.name) / 'tasks.db')
+        self.artifact_root = Path(self.temp_dir.name) / "archive_tmp"
         self.task_repo = TaskRepository(db_path)
         self.history_repo = HistoryRepository(db_path)
         self.path_guard = PathGuard({'storage1': str(self.root1), 'storage2': str(self.root2)})
@@ -47,9 +65,17 @@ class HistoryApiGoldenTest(unittest.TestCase):
         app.dependency_overrides.clear()
         self.temp_dir.cleanup()
 
-    def _set_services(self, filesystem: FilesystemAdapter) -> None:
+    def _set_services(self, filesystem: FilesystemAdapter, file_ops_service: FileOpsService | None = None) -> None:
         runner = TaskRunner(repository=self.task_repo, filesystem=filesystem, history_repository=self.history_repo)
-        file_ops_service = FileOpsService(path_guard=self.path_guard, filesystem=filesystem, history_repository=self.history_repo)
+        file_ops_service = file_ops_service or FileOpsService(path_guard=self.path_guard, filesystem=filesystem, history_repository=self.history_repo)
+        archive_service = ArchiveDownloadTaskService(
+            path_guard=self.path_guard,
+            repository=self.task_repo,
+            runner=runner,
+            history_repository=self.history_repo,
+            file_ops_service=file_ops_service,
+            artifact_root=self.artifact_root,
+        )
         copy_service = CopyTaskService(path_guard=self.path_guard, repository=self.task_repo, runner=runner, history_repository=self.history_repo)
         move_service = MoveTaskService(path_guard=self.path_guard, repository=self.task_repo, runner=runner, history_repository=self.history_repo)
         task_service = TaskService(repository=self.task_repo)
@@ -58,6 +84,9 @@ class HistoryApiGoldenTest(unittest.TestCase):
         async def _override_file_ops_service() -> FileOpsService:
             return file_ops_service
 
+        async def _override_archive_service() -> ArchiveDownloadTaskService:
+            return archive_service
+
         async def _override_copy_service() -> CopyTaskService:
             return copy_service
 
@@ -71,6 +100,7 @@ class HistoryApiGoldenTest(unittest.TestCase):
             return history_service
 
         app.dependency_overrides[get_file_ops_service] = _override_file_ops_service
+        app.dependency_overrides[get_archive_download_task_service] = _override_archive_service
         app.dependency_overrides[get_copy_task_service] = _override_copy_service
         app.dependency_overrides[get_move_task_service] = _override_move_service
         app.dependency_overrides[get_task_service] = _override_task_service
@@ -91,7 +121,7 @@ class HistoryApiGoldenTest(unittest.TestCase):
         while time.time() < deadline:
             response = self._request('GET', f'/api/tasks/{task_id}')
             body = response.json()
-            if body['status'] in {'completed', 'failed', 'ready'}:
+            if body['status'] in {'completed', 'failed', 'ready', 'cancelled'}:
                 return body
             time.sleep(0.02)
         self.fail('task did not reach terminal state in time')
@@ -244,6 +274,38 @@ class HistoryApiGoldenTest(unittest.TestCase):
         self.assertEqual(history[0]['error_code'], 'download_preflight_failed')
         self.assertEqual(history[0]['error_message'], 'Zip download preflight failed')
 
+    def test_download_cancellation_writes_cancelled_history_item(self) -> None:
+        entered = threading.Event()
+        release = threading.Event()
+        file_ops_service = BlockingArchiveBuildFileOpsService(
+            path_guard=self.path_guard,
+            filesystem=FilesystemAdapter(),
+            history_repository=self.history_repo,
+            entered=entered,
+            release=release,
+        )
+        self._set_services(FilesystemAdapter(), file_ops_service=file_ops_service)
+        (self.root1 / 'docs').mkdir()
+        (self.root1 / 'docs' / 'a.txt').write_text('A', encoding='utf-8')
+
+        response = self._request('POST', '/api/files/download/archive-prepare', {'paths': ['storage1/docs']})
+
+        self.assertEqual(response.status_code, 202)
+        self.assertTrue(entered.wait(timeout=2.0))
+        cancel = self._request('POST', f"/api/files/download/archive/{response.json()['task_id']}/cancel")
+        release.set()
+        self._wait_task(response.json()['task_id'])
+        history = self._request('GET', '/api/history').json()['items']
+
+        self.assertEqual(cancel.status_code, 200)
+        self.assertEqual(history[0]['operation'], 'download')
+        self.assertEqual(history[0]['status'], 'cancelled')
+        self.assertEqual(history[0]['source'], 'single_directory_zip')
+        self.assertEqual(history[0]['path'], 'storage1/docs')
+        self.assertEqual(history[0]['destination'], 'docs.zip')
+        self.assertEqual(history[0]['error_code'], None)
+        self.assertEqual(history[0]['error_message'], None)
+
     def test_download_history_uses_server_certain_statuses_only(self) -> None:
         (self.root1 / 'report.txt').write_text('hello download', encoding='utf-8')
 
@@ -251,5 +313,5 @@ class HistoryApiGoldenTest(unittest.TestCase):
 
         self.assertEqual(response.status_code, 200)
         history = self._request('GET', '/api/history').json()['items']
-        self.assertIn(history[0]['status'], {'requested', 'ready', 'preflight_failed', 'failed'})
+        self.assertIn(history[0]['status'], {'requested', 'ready', 'preflight_failed', 'failed', 'cancelled'})
         self.assertNotIn(history[0]['status'], {'completed', 'downloaded', 'saved'})

webui/backend/tests/golden/test_api_tasks_golden.py

@@ -263,6 +263,28 @@ class TasksApiGoldenTest(unittest.TestCase):
         self.assertEqual(body["status"], "ready")
         self.assertEqual(body["destination"], "docs.zip")
 
+    def test_get_task_detail_cancelled_archive_download(self) -> None:
+        self._insert_task(
+            task_id="task-download-cancelled",
+            operation="download",
+            status="cancelled",
+            source="storage1/docs",
+            destination="docs.zip",
+            created_at="2026-03-10T10:00:00Z",
+            started_at="2026-03-10T10:00:01Z",
+            finished_at="2026-03-10T10:00:03Z",
+            done_items=0,
+            total_items=1,
+        )
+
+        response = self._get("/api/tasks/task-download-cancelled")
+
+        self.assertEqual(response.status_code, 200)
+        body = response.json()
+        self.assertEqual(body["operation"], "download")
+        self.assertEqual(body["status"], "cancelled")
+        self.assertEqual(body["destination"], "docs.zip")
+
     def test_get_task_not_found(self) -> None:
         response = self._get("/api/tasks/task-missing")
 

webui/backend/tests/golden/test_ui_smoke_golden.py

@@ -74,6 +74,7 @@ class UiSmokeGoldenTest(unittest.TestCase):
         self.assertIn('id="download-modal-progress-bar"', body)
         self.assertIn('id="download-modal-count"', body)
         self.assertIn('id="download-modal-status"', body)
+        self.assertIn('id="download-modal-cancel-btn"', body)
         self.assertIn('id="download-modal-close-btn"', body)
         self.assertIn('id="context-menu"', body)
         self.assertIn('id="context-menu-scope"', body)
@@ -231,11 +232,14 @@ class UiSmokeGoldenTest(unittest.TestCase):
         self.assertIn('function openZipDownloadModal(selectedItems)', app_js)
         self.assertIn('function markZipDownloadReady(fileName)', app_js)
         self.assertIn('function markZipDownloadFailed(err)', app_js)
+        self.assertIn('function markZipDownloadCancelled()', app_js)
         self.assertIn('function closeDownloadModal()', app_js)
         self.assertIn('function zipDownloadRequestKey(paths)', app_js)
         self.assertIn('async function createArchiveDownloadTask(paths)', app_js)
         self.assertIn('async function getTaskRequest(taskId)', app_js)
+        self.assertIn('async function cancelArchiveDownloadTask(taskId)', app_js)
         self.assertIn('function startArchiveDownload(taskId, fileName)', app_js)
+        self.assertIn('async function requestArchiveDownloadCancel()', app_js)
         self.assertIn('async function waitForArchiveDownloadReady(taskId)', app_js)
         self.assertIn('function contextMenuElements()', app_js)
         self.assertIn('function openContextMenu(pane, entry, event)', app_js)
@@ -251,12 +255,15 @@ class UiSmokeGoldenTest(unittest.TestCase):
         self.assertIn('statusText: "Download started"', app_js)
         self.assertIn('countText: "Browser download started"', app_js)
         self.assertIn('countText: "Zip download failed"', app_js)
+        self.assertIn('countText: "Zip download cancelled"', app_js)
+        self.assertIn('statusText: "Cancelling download..."', app_js)
         self.assertIn('statusText: err.message || "Download failed"', app_js)
         self.assertIn('downloadProgressState.requestKey === requestKey', app_js)
         self.assertIn('setStatus("Preparing download...");', app_js)
         self.assertIn('"/api/files/download/archive-prepare"', app_js)
         self.assertIn('`/api/tasks/${encodeURIComponent(taskId)}`', app_js)
         self.assertIn('`/api/files/download/archive/${encodeURIComponent(taskId)}`', app_js)
+        self.assertIn('`/api/files/download/archive/${encodeURIComponent(taskId)}/cancel`', app_js)
         self.assertIn('function applyContextMenuSelection()', app_js)
         self.assertIn('function startContextMenuOpen()', app_js)
         self.assertIn('function startContextMenuEdit()', app_js)

webui/backend/tests/unit/test_task_repository.py

@@ -80,6 +80,21 @@ class TaskRepositoryTest(unittest.TestCase):
         self.assertEqual(task["status"], "requested")
         self.assertEqual(artifact["file_name"], "docs.zip")
 
+    def test_mark_cancelled_transitions_requested_download_task(self) -> None:
+        created = self.repo.create_task(
+            operation="download",
+            source="storage1/docs",
+            destination="docs.zip",
+            status="requested",
+        )
+
+        changed = self.repo.mark_cancelled(created["id"])
+        task = self.repo.get_task(created["id"])
+
+        self.assertTrue(changed)
+        self.assertEqual(task["status"], "cancelled")
+        self.assertIsNotNone(task["finished_at"])
+
     def test_migrates_legacy_tasks_schema_missing_source_destination(self) -> None:
         legacy_db_path = Path(self.temp_dir.name) / "legacy.db"
         conn = sqlite3.connect(legacy_db_path)

webui/html/app.js

@@ -86,6 +86,8 @@ let downloadProgressState = {
   archiveLabel: "",
   totalItems: 0,
   requestKey: null,
+  taskId: null,
+  cancelRequested: false,
 };
 let folderUploadPlanState = {
   targetPane: "left",
@@ -336,6 +338,7 @@ function downloadModalElements() {
     count: document.getElementById("download-modal-count"),
     progressBar: document.getElementById("download-modal-progress-bar"),
     status: document.getElementById("download-modal-status"),
+    cancelButton: document.getElementById("download-modal-cancel-btn"),
     closeButton: document.getElementById("download-modal-close-btn"),
   };
 }
@@ -400,6 +403,8 @@ function updateDownloadModalDisplay(info) {
   elements.count.textContent = info.countText || "";
   elements.status.textContent = info.statusText || "";
   elements.progressBar.style.width = `${Math.max(0, Math.min(100, info.percent || 0))}%`;
+  elements.cancelButton.disabled = !!info.cancelDisabled;
+  elements.cancelButton.classList.toggle("hidden", !info.cancelVisible);
   elements.closeButton.disabled = !!info.active;
   elements.closeButton.classList.toggle("hidden", !!info.active);
 }
@@ -410,6 +415,8 @@ function openZipDownloadModal(selectedItems) {
   downloadProgressState.archiveLabel = "ZIP archive";
   downloadProgressState.totalItems = selectedItems.length;
   downloadProgressState.requestKey = zipDownloadRequestKey(requestPaths);
+  downloadProgressState.taskId = null;
+  downloadProgressState.cancelRequested = false;
   setDownloadModalVisible(true);
   updateDownloadModalDisplay({
     active: true,
@@ -418,6 +425,8 @@ function openZipDownloadModal(selectedItems) {
     countText: "Preparing zip download",
     statusText: "Preparing download...",
     percent: 20,
+    cancelVisible: true,
+    cancelDisabled: true,
   });
   requestAnimationFrame(() => {
     if (!downloadProgressState.active) {
@@ -430,12 +439,15 @@ function openZipDownloadModal(selectedItems) {
       countText: "Zip preflight and packaging",
       statusText: "Preparing download...",
       percent: 55,
+      cancelVisible: true,
+      cancelDisabled: !downloadProgressState.taskId || downloadProgressState.cancelRequested,
     });
   });
 }
 
 function markZipDownloadReady(fileName) {
   downloadProgressState.active = false;
+  downloadProgressState.cancelRequested = false;
   downloadProgressState.archiveLabel = fileName || "ZIP archive";
   updateDownloadModalDisplay({
     active: false,
@@ -444,12 +456,14 @@ function markZipDownloadReady(fileName) {
     countText: "Browser download started",
     statusText: "Download started",
     percent: 100,
+    cancelVisible: false,
   });
   window.setTimeout(closeDownloadModal, 480);
 }
 
 function markZipDownloadFailed(err) {
   downloadProgressState.active = false;
+  downloadProgressState.cancelRequested = false;
   updateDownloadModalDisplay({
     active: false,
     targetText: "Preparing download...",
@@ -457,6 +471,21 @@ function markZipDownloadFailed(err) {
     countText: "Zip download failed",
     statusText: err.message || "Download failed",
     percent: 0,
+    cancelVisible: false,
+  });
+}
+
+function markZipDownloadCancelled() {
+  downloadProgressState.active = false;
+  downloadProgressState.cancelRequested = false;
+  updateDownloadModalDisplay({
+    active: false,
+    targetText: "Download cancelled",
+    currentFileText: `Selection: ${selectedItemCountLabel(downloadProgressState.totalItems)}`,
+    countText: "Zip download cancelled",
+    statusText: "Download cancelled",
+    percent: 0,
+    cancelVisible: false,
   });
 }
 
@@ -469,8 +498,10 @@ function updateZipDownloadTaskProgress(task) {
     targetText: "Preparing download...",
     currentFileText: task.current_item ? `Current: ${task.current_item}` : `Selection: ${selectedItemCountLabel(downloadProgressState.totalItems)}`,
     countText: task.total_items ? `${task.done_items || 0}/${task.total_items} top-level items` : "Preparing zip download",
-    statusText: task.status === "ready" ? "Download started" : "Preparing download...",
+    statusText: downloadProgressState.cancelRequested ? "Cancelling download..." : task.status === "ready" ? "Download started" : "Preparing download...",
     percent: task.status === "ready" ? 100 : 55,
+    cancelVisible: true,
+    cancelDisabled: !downloadProgressState.taskId || downloadProgressState.cancelRequested,
   });
 }
 
@@ -484,6 +515,11 @@ async function waitForArchiveDownloadReady(taskId) {
     if (task.status === "ready") {
       return task;
     }
+    if (task.status === "cancelled") {
+      const err = new Error("Archive download was cancelled");
+      err.code = "download_cancelled";
+      throw err;
+    }
     if (task.status === "failed") {
       const err = new Error(task.error_message || "Archive download failed");
       err.code = task.error_code || null;
@@ -501,6 +537,8 @@ function closeDownloadModal() {
   downloadProgressState.archiveLabel = "";
   downloadProgressState.totalItems = 0;
   downloadProgressState.requestKey = null;
+  downloadProgressState.taskId = null;
+  downloadProgressState.cancelRequested = false;
   updateDownloadModalDisplay({
     active: false,
     targetText: "",
@@ -508,6 +546,7 @@ function closeDownloadModal() {
     countText: "",
     statusText: "",
     percent: 0,
+    cancelVisible: false,
   });
   setDownloadModalVisible(false);
 }
@@ -679,6 +718,13 @@ async function startDownloadSelected() {
     const selected = selectedItems[0];
     if (zipDownload) {
       const created = await createArchiveDownloadTask(selectedPaths);
+      downloadProgressState.taskId = created.task_id;
+      updateZipDownloadTaskProgress({
+        status: "preparing",
+        current_item: null,
+        done_items: 0,
+        total_items: selectedItems.length,
+      });
       const task = await waitForArchiveDownloadReady(created.task_id);
       startArchiveDownload(task.id, task.destination);
       markZipDownloadReady(task.destination);
@@ -697,8 +743,13 @@ async function startDownloadSelected() {
     setStatus(`Download started: ${anchor.download}`);
   } catch (err) {
     if (zipDownload) {
+      if (err.code === "download_cancelled") {
+        markZipDownloadCancelled();
+        setStatus("Download cancelled");
+      } else {
         markZipDownloadFailed(err);
         setStatus("Download failed");
+      }
     } else {
       setActionError("Download", err);
     }
@@ -1004,6 +1055,10 @@ async function getTaskRequest(taskId) {
   return apiRequest("GET", `/api/tasks/${encodeURIComponent(taskId)}`);
 }
 
+async function cancelArchiveDownloadTask(taskId) {
+  return apiRequest("POST", `/api/files/download/archive/${encodeURIComponent(taskId)}/cancel`);
+}
+
 function startArchiveDownload(taskId, fileName) {
   const anchor = document.createElement("a");
   anchor.href = `/api/files/download/archive/${encodeURIComponent(taskId)}`;
@@ -1013,6 +1068,31 @@ function startArchiveDownload(taskId, fileName) {
   anchor.remove();
 }
 
+async function requestArchiveDownloadCancel() {
+  if (!downloadProgressState.active || !downloadProgressState.taskId || downloadProgressState.cancelRequested) {
+    return;
+  }
+  downloadProgressState.cancelRequested = true;
+  updateDownloadModalDisplay({
+    active: true,
+    targetText: "Preparing download...",
+    currentFileText: `Selection: ${selectedItemCountLabel(downloadProgressState.totalItems)}`,
+    countText: "Zip download cancellation requested",
+    statusText: "Cancelling download...",
+    percent: 55,
+    cancelVisible: true,
+    cancelDisabled: true,
+  });
+  try {
+    await cancelArchiveDownloadTask(downloadProgressState.taskId);
+  } catch (err) {
+    if (err.code !== "download_not_cancellable") {
+      downloadProgressState.cancelRequested = false;
+      throw err;
+    }
+  }
+}
+
 async function uploadFileRequest(targetPath, file, overwrite = false) {
   const formData = new FormData();
   formData.append("target_path", targetPath);
@@ -4164,6 +4244,14 @@ function setupEvents() {
     };
   }
   const downloadModal = downloadModalElements();
+  if (downloadModal.cancelButton) {
+    downloadModal.cancelButton.onclick = () => {
+      requestArchiveDownloadCancel().catch((err) => {
+        markZipDownloadFailed(err);
+        setStatus("Download failed");
+      });
+    };
+  }
   if (downloadModal.closeButton) {
     downloadModal.closeButton.onclick = closeDownloadModal;
   }

webui/html/index.html

@@ -129,6 +129,7 @@
       <div id="download-modal-count" class="download-modal-count"></div>
       <div id="download-modal-status" class="popup-meta"></div>
       <div class="popup-actions">
+        <button id="download-modal-cancel-btn" type="button" class="hidden">Cancel</button>
         <button id="download-modal-close-btn" type="button">Close</button>
       </div>
     </div>