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diff --git a/webui/backend/app/api/__pycache__/routes_duplicate.cpython-313.pyc b/webui/backend/app/api/__pycache__/routes_duplicate.cpython-313.pyc
new file mode 100644
index 0000000..0731e7b
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diff --git a/webui/backend/app/api/__pycache__/schemas.cpython-313.pyc b/webui/backend/app/api/__pycache__/schemas.cpython-313.pyc
index abc3728..f326901 100644
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diff --git a/webui/backend/app/api/routes_duplicate.py b/webui/backend/app/api/routes_duplicate.py
new file mode 100644
index 0000000..72e680b
--- /dev/null
+++ b/webui/backend/app/api/routes_duplicate.py
@@ -0,0 +1,17 @@
+from __future__ import annotations
+
+from fastapi import APIRouter, Depends
+
+from backend.app.api.schemas import DuplicateRequest, TaskCreateResponse
+from backend.app.dependencies import get_duplicate_task_service
+from backend.app.services.duplicate_task_service import DuplicateTaskService
+
+router = APIRouter(prefix="/files")
+
+
+@router.post("/duplicate", response_model=TaskCreateResponse, status_code=202)
+async def duplicate_paths(
+    request: DuplicateRequest,
+    service: DuplicateTaskService = Depends(get_duplicate_task_service),
+) -> TaskCreateResponse:
+    return service.create_duplicate_task(paths=request.paths)
diff --git a/webui/backend/app/api/schemas.py b/webui/backend/app/api/schemas.py
index 6db03cd..afb46c4 100644
--- a/webui/backend/app/api/schemas.py
+++ b/webui/backend/app/api/schemas.py
@@ -172,6 +172,10 @@ class CopyRequest(BaseModel):
     destination_base: str | None = None
 
 
+class DuplicateRequest(BaseModel):
+    paths: list[str]
+
+
 class TaskCreateResponse(BaseModel):
     task_id: str
     status: str
diff --git a/webui/backend/app/db/__pycache__/history_repository.cpython-313.pyc b/webui/backend/app/db/__pycache__/history_repository.cpython-313.pyc
index c232b76..581c374 100644
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diff --git a/webui/backend/app/db/__pycache__/task_repository.cpython-313.pyc b/webui/backend/app/db/__pycache__/task_repository.cpython-313.pyc
index da7a6d7..11d23ee 100644
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diff --git a/webui/backend/app/db/history_repository.py b/webui/backend/app/db/history_repository.py
index 209ef8f..1e0acd4 100644
--- a/webui/backend/app/db/history_repository.py
+++ b/webui/backend/app/db/history_repository.py
@@ -7,7 +7,7 @@ from datetime import datetime, timezone
 from pathlib import Path
 
 VALID_HISTORY_STATUSES = {"queued", "completed", "failed", "requested", "ready", "preflight_failed", "cancelled"}
-VALID_HISTORY_OPERATIONS = {"mkdir", "rename", "delete", "copy", "move", "upload", "download"}
+VALID_HISTORY_OPERATIONS = {"mkdir", "rename", "delete", "copy", "move", "upload", "download", "duplicate"}
 
 
 class HistoryRepository:
diff --git a/webui/backend/app/db/task_repository.py b/webui/backend/app/db/task_repository.py
index 65c5372..27a8b6e 100644
--- a/webui/backend/app/db/task_repository.py
+++ b/webui/backend/app/db/task_repository.py
@@ -7,7 +7,7 @@ from datetime import datetime, timezone
 from pathlib import Path
 
 VALID_STATUSES = {"queued", "running", "completed", "failed", "requested", "preparing", "ready", "cancelled"}
-VALID_OPERATIONS = {"copy", "move", "download"}
+VALID_OPERATIONS = {"copy", "move", "download", "duplicate"}
 TASK_MIGRATION_COLUMNS: dict[str, str] = {
     "operation": "TEXT NOT NULL DEFAULT 'copy'",
     "status": "TEXT NOT NULL DEFAULT 'queued'",
diff --git a/webui/backend/app/dependencies.py b/webui/backend/app/dependencies.py
index c0a8ac6..061b3d6 100644
--- a/webui/backend/app/dependencies.py
+++ b/webui/backend/app/dependencies.py
@@ -14,6 +14,7 @@ from backend.app.services.bookmark_service import BookmarkService
 from backend.app.services.browse_service import BrowseService
 from backend.app.services.copy_task_service import CopyTaskService
 from backend.app.services.archive_download_task_service import ArchiveDownloadTaskService
+from backend.app.services.duplicate_task_service import DuplicateTaskService
 from backend.app.services.file_ops_service import FileOpsService
 from backend.app.services.history_service import HistoryService
 from backend.app.services.move_task_service import MoveTaskService
@@ -112,6 +113,15 @@ async def get_copy_task_service() -> CopyTaskService:
     )
 
 
+async def get_duplicate_task_service() -> DuplicateTaskService:
+    return DuplicateTaskService(
+        path_guard=get_path_guard(),
+        repository=get_task_repository(),
+        runner=get_task_runner(),
+        history_repository=get_history_repository(),
+    )
+
+
 async def get_move_task_service() -> MoveTaskService:
     return MoveTaskService(
         path_guard=get_path_guard(),
diff --git a/webui/backend/app/main.py b/webui/backend/app/main.py
index e07a32e..182bb10 100644
--- a/webui/backend/app/main.py
+++ b/webui/backend/app/main.py
@@ -10,6 +10,7 @@ from backend.app.api.errors import AppError
 from backend.app.api.routes_bookmarks import router as bookmarks_router
 from backend.app.api.routes_browse import router as browse_router
 from backend.app.api.routes_copy import router as copy_router
+from backend.app.api.routes_duplicate import router as duplicate_router
 from backend.app.api.routes_files import router as files_router
 from backend.app.api.routes_history import router as history_router
 from backend.app.api.routes_move import router as move_router
@@ -30,6 +31,7 @@ app.mount("/ui", StaticFiles(directory=str(UI_DIR), html=True), name="ui")
 app.include_router(browse_router, prefix="/api")
 app.include_router(files_router, prefix="/api")
 app.include_router(copy_router, prefix="/api")
+app.include_router(duplicate_router, prefix="/api")
 app.include_router(move_router, prefix="/api")
 app.include_router(search_router, prefix="/api")
 app.include_router(settings_router, prefix="/api")
diff --git a/webui/backend/app/services/__pycache__/duplicate_task_service.cpython-313.pyc b/webui/backend/app/services/__pycache__/duplicate_task_service.cpython-313.pyc
new file mode 100644
index 0000000..33bfdba
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diff --git a/webui/backend/app/services/duplicate_task_service.py b/webui/backend/app/services/duplicate_task_service.py
new file mode 100644
index 0000000..2442e1e
--- /dev/null
+++ b/webui/backend/app/services/duplicate_task_service.py
@@ -0,0 +1,188 @@
+from __future__ import annotations
+
+import os
+import uuid
+from datetime import datetime, timezone
+from pathlib import Path
+
+from backend.app.api.errors import AppError
+from backend.app.api.schemas import TaskCreateResponse
+from backend.app.db.history_repository import HistoryRepository
+from backend.app.db.task_repository import TaskRepository
+from backend.app.security.path_guard import PathGuard, ResolvedPath
+from backend.app.tasks_runner import TaskRunner
+
+
+class DuplicateTaskService:
+    def __init__(self, path_guard: PathGuard, repository: TaskRepository, runner: TaskRunner, history_repository: HistoryRepository | None = None):
+        self._path_guard = path_guard
+        self._repository = repository
+        self._runner = runner
+        self._history_repository = history_repository
+
+    def create_duplicate_task(self, paths: list[str] | None) -> TaskCreateResponse:
+        if not paths:
+            raise AppError(
+                code="invalid_request",
+                message="At least 1 path is required",
+                status_code=400,
+            )
+        try:
+            items: list[dict[str, str]] = []
+            reserved_destinations: set[str] = set()
+            for input_path in paths:
+                item = self._build_duplicate_item(input_path, reserved_destinations)
+                if item is None:
+                    continue
+                reserved_destinations.add(item["destination_absolute"])
+                items.append(item)
+
+            source_summary = self._source_summary(paths, items)
+            destination_summary = self._destination_summary(items)
+            task_id = str(uuid.uuid4())
+            task = self._repository.create_task(
+                operation="duplicate",
+                source=source_summary,
+                destination=destination_summary,
+                task_id=task_id,
+            )
+            self._record_history(
+                entry_id=task_id,
+                operation="duplicate",
+                status="queued",
+                source=source_summary,
+                destination=destination_summary,
+            )
+            self._runner.enqueue_duplicate_batch(
+                task_id=task["id"],
+                items=[
+                    {
+                        "source": item["source_absolute"],
+                        "destination": item["destination_absolute"],
+                        "kind": item["kind"],
+                    }
+                    for item in items
+                ],
+            )
+            return TaskCreateResponse(task_id=task["id"], status=task["status"])
+        except AppError as exc:
+            self._record_history(
+                operation="duplicate",
+                status="failed",
+                source=paths[0] if len(paths) == 1 else f"{len(paths)} items",
+                destination="same directory",
+                error_code=exc.code,
+                error_message=exc.message,
+                finished_at=self._now_iso(),
+            )
+            raise
+
+    def _build_duplicate_item(self, source: str, reserved_destinations: set[str]) -> dict[str, str] | None:
+        resolved_source = self._path_guard.resolve_existing_path(source)
+        _, _, lexical_source, _ = self._path_guard.resolve_lexical_path(source)
+        if self._should_skip_name(lexical_source.name):
+            return None
+        if lexical_source.is_symlink():
+            raise AppError(
+                code="type_conflict",
+                message="Source must not be a symlink",
+                status_code=409,
+                details={"path": source},
+            )
+
+        source_is_file = resolved_source.absolute.is_file()
+        source_is_directory = resolved_source.absolute.is_dir()
+        if not source_is_file and not source_is_directory:
+            raise AppError(
+                code="type_conflict",
+                message="Unsupported source path type",
+                status_code=409,
+                details={"path": source},
+            )
+
+        if source_is_directory:
+            self._validate_directory_tree(resolved_source)
+
+        destination_absolute = self._next_duplicate_destination(resolved_source.absolute, reserved_destinations)
+        destination_relative = self._path_guard.entry_relative_path(
+            resolved_source.alias,
+            destination_absolute,
+            display_style=resolved_source.display_style,
+        )
+
+        return {
+            "source_relative": resolved_source.relative,
+            "destination_relative": destination_relative,
+            "source_absolute": str(resolved_source.absolute),
+            "destination_absolute": str(destination_absolute),
+            "kind": "directory" if source_is_directory else "file",
+        }
+
+    def _validate_directory_tree(self, resolved_source: ResolvedPath) -> None:
+        for root, dirnames, filenames in os.walk(resolved_source.absolute, followlinks=False):
+            dirnames[:] = [name for name in dirnames if not self._should_skip_name(name)]
+            root_path = Path(root)
+            for name in [*dirnames, *filenames]:
+                if self._should_skip_name(name):
+                    continue
+                entry = root_path / name
+                if entry.is_symlink():
+                    raise AppError(
+                        code="type_conflict",
+                        message="Source directory must not contain symlinks",
+                        status_code=409,
+                        details={"path": resolved_source.relative},
+                    )
+
+    @classmethod
+    def _next_duplicate_destination(cls, source: Path, reserved_destinations: set[str]) -> Path:
+        parent = source.parent
+        candidate_index = 1
+        while True:
+            candidate_name = cls._duplicate_name(source.name, source.is_file(), candidate_index)
+            candidate = parent / candidate_name
+            if not candidate.exists() and str(candidate) not in reserved_destinations:
+                return candidate
+            candidate_index += 1
+
+    @classmethod
+    def _duplicate_name(cls, original_name: str, is_file: bool, index: int) -> str:
+        if not is_file:
+            suffix = ""
+            base_name = original_name
+        else:
+            suffixes = Path(original_name).suffixes
+            suffix = "".join(suffixes)
+            base_name = original_name[: -len(suffix)] if suffix else original_name
+        copy_suffix = " copy" if index == 1 else f" copy {index}"
+        return f"{base_name}{copy_suffix}{suffix}"
+
+    @staticmethod
+    def _should_skip_name(name: str) -> bool:
+        return name.startswith("._")
+
+    @staticmethod
+    def _source_summary(paths: list[str], items: list[dict[str, str]]) -> str:
+        if len(paths) == 1:
+            return paths[0]
+        if not items:
+            return "0 items"
+        return DuplicateTaskService._items_label(len(items))
+
+    @staticmethod
+    def _destination_summary(items: list[dict[str, str]]) -> str:
+        if len(items) == 1:
+            return items[0]["destination_relative"]
+        return "same directory"
+
+    @staticmethod
+    def _items_label(count: int) -> str:
+        return "1 item" if count == 1 else f"{count} items"
+
+    def _record_history(self, **kwargs) -> None:
+        if self._history_repository:
+            self._history_repository.create_entry(**kwargs)
+
+    @staticmethod
+    def _now_iso() -> str:
+        return datetime.now(timezone.utc).replace(microsecond=0).isoformat().replace("+00:00", "Z")
diff --git a/webui/backend/app/tasks_runner.py b/webui/backend/app/tasks_runner.py
index e536593..f124391 100644
--- a/webui/backend/app/tasks_runner.py
+++ b/webui/backend/app/tasks_runner.py
@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import os
+import shutil
 import threading
 from pathlib import Path
 
@@ -69,6 +71,14 @@ class TaskRunner:
         )
         thread.start()
 
+    def enqueue_duplicate_batch(self, task_id: str, items: list[dict[str, str]]) -> None:
+        thread = threading.Thread(
+            target=self._run_duplicate_batch,
+            args=(task_id, items),
+            daemon=True,
+        )
+        thread.start()
+
     def enqueue_archive_prepare(self, worker) -> None:
         thread = threading.Thread(
             target=worker,
@@ -322,6 +332,97 @@ class TaskRunner:
         )
         self._update_history_completed(task_id)
 
+    def _run_duplicate_batch(self, task_id: str, items: list[dict[str, str]]) -> None:
+        total_items = len(items)
+        current_item = items[0]["source"] if items else None
+        self._repository.mark_running(
+            task_id=task_id,
+            done_items=0,
+            total_items=total_items,
+            current_item=current_item,
+        )
+
+        completed_items = 0
+        for index, item in enumerate(items):
+            source = item["source"]
+            destination = item["destination"]
+            try:
+                if item["kind"] == "directory":
+                    self._duplicate_directory(source=Path(source), destination=Path(destination))
+                else:
+                    self._filesystem.copy_file(source=source, destination=destination)
+                completed_items = index + 1
+                next_item = items[index + 1]["source"] if index + 1 < total_items else source
+                self._repository.update_progress(
+                    task_id=task_id,
+                    done_items=completed_items,
+                    total_items=total_items,
+                    current_item=next_item,
+                )
+            except OSError as exc:
+                self._cleanup_partial_duplicate(Path(destination))
+                self._repository.mark_failed(
+                    task_id=task_id,
+                    error_code="io_error",
+                    error_message=str(exc),
+                    failed_item=source,
+                    done_bytes=None,
+                    total_bytes=None,
+                    done_items=completed_items,
+                    total_items=total_items,
+                )
+                self._update_history_failed(task_id, str(exc))
+                return
+
+        self._repository.mark_completed(
+            task_id=task_id,
+            done_items=total_items,
+            total_items=total_items,
+        )
+        self._update_history_completed(task_id)
+
+    def _duplicate_directory(self, source: Path, destination: Path) -> None:
+        destination.mkdir()
+        copied_directories: list[tuple[Path, Path]] = [(source, destination)]
+        try:
+            for root, dirnames, filenames in os.walk(source, topdown=True, followlinks=False):
+                root_path = Path(root)
+                target_root = destination / root_path.relative_to(source)
+                dirnames[:] = [name for name in dirnames if not name.startswith("._")]
+
+                for name in dirnames:
+                    source_dir = root_path / name
+                    if source_dir.is_symlink():
+                        raise OSError("Source directory must not contain symlinks")
+                    target_dir = target_root / name
+                    target_dir.mkdir()
+                    copied_directories.append((source_dir, target_dir))
+
+                for name in filenames:
+                    if name.startswith("._"):
+                        continue
+                    source_file = root_path / name
+                    if source_file.is_symlink():
+                        raise OSError("Source directory must not contain symlinks")
+                    self._filesystem.copy_file(
+                        source=str(source_file),
+                        destination=str(target_root / name),
+                    )
+
+            for source_dir, target_dir in reversed(copied_directories):
+                shutil.copystat(source_dir, target_dir, follow_symlinks=False)
+        except Exception:
+            self._cleanup_partial_duplicate(destination)
+            raise
+
+    def _cleanup_partial_duplicate(self, path: Path) -> None:
+        if not path.exists():
+            return
+        if path.is_dir():
+            shutil.rmtree(path)
+            return
+        path.unlink()
+
     def _update_history_completed(self, task_id: str) -> None:
         if self._history_repository:
             self._history_repository.update_entry(entry_id=task_id, status="completed")
diff --git a/webui/backend/data/archive_tmp/ae8c717c-02a9-4179-b7f1-307675d64ee3.zip b/webui/backend/data/archive_tmp/b00fba24-e752-405f-98a7-6f2c21fa3a1c.zip
similarity index 61%
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deleted file mode 100644
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diff --git a/webui/backend/tests/golden/__pycache__/test_api_tasks_golden.cpython-313.pyc b/webui/backend/tests/golden/__pycache__/test_api_tasks_golden.cpython-313.pyc
index c7c1256..f599807 100644
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diff --git a/webui/backend/tests/golden/test_api_duplicate_golden.py b/webui/backend/tests/golden/test_api_duplicate_golden.py
new file mode 100644
index 0000000..4c0feb2
--- /dev/null
+++ b/webui/backend/tests/golden/test_api_duplicate_golden.py
@@ -0,0 +1,202 @@
+from __future__ import annotations
+
+import asyncio
+import sys
+import tempfile
+import time
+import unittest
+from pathlib import Path
+
+import httpx
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[3]))
+
+from backend.app.dependencies import get_duplicate_task_service, get_task_service
+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.duplicate_task_service import DuplicateTaskService
+from backend.app.services.task_service import TaskService
+from backend.app.tasks_runner import TaskRunner
+
+
+class FailOnSecondCopyFilesystemAdapter(FilesystemAdapter):
+    def __init__(self) -> None:
+        super().__init__()
+        self._copy_calls = 0
+
+    def copy_file(self, source: str, destination: str, on_progress: callable | None = None) -> None:
+        self._copy_calls += 1
+        if self._copy_calls == 2:
+            raise OSError("forced duplicate failure")
+        super().copy_file(source=source, destination=destination, on_progress=on_progress)
+
+
+class DuplicateApiGoldenTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self.temp_dir = tempfile.TemporaryDirectory()
+        self.root = Path(self.temp_dir.name) / "root"
+        self.root.mkdir(parents=True, exist_ok=True)
+        self.repo = TaskRepository(str(Path(self.temp_dir.name) / "tasks.db"))
+        path_guard = PathGuard({"storage1": str(self.root), "storage2": str(self.root)})
+        self._set_services(path_guard=path_guard, filesystem=FilesystemAdapter())
+
+    def tearDown(self) -> None:
+        app.dependency_overrides.clear()
+        self.temp_dir.cleanup()
+
+    def _set_services(self, path_guard: PathGuard, filesystem: FilesystemAdapter) -> None:
+        runner = TaskRunner(repository=self.repo, filesystem=filesystem)
+        duplicate_service = DuplicateTaskService(path_guard=path_guard, repository=self.repo, runner=runner)
+        task_service = TaskService(repository=self.repo)
+
+        async def _override_duplicate_service() -> DuplicateTaskService:
+            return duplicate_service
+
+        async def _override_task_service() -> TaskService:
+            return task_service
+
+        app.dependency_overrides[get_duplicate_task_service] = _override_duplicate_service
+        app.dependency_overrides[get_task_service] = _override_task_service
+
+    def _request(self, method: str, url: str, payload: dict | None = None) -> httpx.Response:
+        async def _run() -> httpx.Response:
+            transport = httpx.ASGITransport(app=app)
+            async with httpx.AsyncClient(transport=transport, base_url="http://testserver") as client:
+                if method == "POST":
+                    return await client.post(url, json=payload)
+                return await client.get(url)
+
+        return asyncio.run(_run())
+
+    def _wait_task(self, task_id: str, timeout_s: float = 2.0) -> dict:
+        deadline = time.time() + timeout_s
+        while time.time() < deadline:
+            response = self._request("GET", f"/api/tasks/{task_id}")
+            body = response.json()
+            if body["status"] in {"completed", "failed"}:
+                return body
+            time.sleep(0.02)
+        self.fail("task did not reach terminal state in time")
+
+    def test_duplicate_single_file_success(self) -> None:
+        (self.root / "note.txt").write_text("hello", encoding="utf-8")
+
+        response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/note.txt"]})
+
+        self.assertEqual(response.status_code, 202)
+        detail = self._wait_task(response.json()["task_id"])
+        self.assertEqual(detail["operation"], "duplicate")
+        self.assertEqual(detail["status"], "completed")
+        self.assertEqual(detail["done_items"], 1)
+        self.assertEqual(detail["total_items"], 1)
+        self.assertEqual(detail["source"], "storage1/note.txt")
+        self.assertEqual(detail["destination"], "storage1/note copy.txt")
+        self.assertEqual((self.root / "note copy.txt").read_text(encoding="utf-8"), "hello")
+
+    def test_duplicate_single_directory_success(self) -> None:
+        (self.root / "Folder" / "nested").mkdir(parents=True)
+        (self.root / "Folder" / "alpha.txt").write_text("A", encoding="utf-8")
+        (self.root / "Folder" / "nested" / "beta.txt").write_text("B", encoding="utf-8")
+
+        response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/Folder"]})
+
+        self.assertEqual(response.status_code, 202)
+        detail = self._wait_task(response.json()["task_id"])
+        self.assertEqual(detail["status"], "completed")
+        self.assertEqual(detail["done_items"], 1)
+        self.assertEqual(detail["total_items"], 1)
+        self.assertTrue((self.root / "Folder copy").is_dir())
+        self.assertEqual((self.root / "Folder copy" / "alpha.txt").read_text(encoding="utf-8"), "A")
+        self.assertEqual((self.root / "Folder copy" / "nested" / "beta.txt").read_text(encoding="utf-8"), "B")
+
+    def test_duplicate_multi_select_success(self) -> None:
+        (self.root / "a.txt").write_text("A", encoding="utf-8")
+        (self.root / "docs" / "nested").mkdir(parents=True)
+        (self.root / "docs" / "nested" / "b.txt").write_text("B", encoding="utf-8")
+
+        response = self._request(
+            "POST",
+            "/api/files/duplicate",
+            {"paths": ["storage1/a.txt", "storage1/docs"]},
+        )
+
+        self.assertEqual(response.status_code, 202)
+        detail = self._wait_task(response.json()["task_id"])
+        self.assertEqual(detail["status"], "completed")
+        self.assertEqual(detail["done_items"], 2)
+        self.assertEqual(detail["total_items"], 2)
+        self.assertEqual(detail["source"], "2 items")
+        self.assertEqual(detail["destination"], "same directory")
+        self.assertEqual((self.root / "a copy.txt").read_text(encoding="utf-8"), "A")
+        self.assertEqual((self.root / "docs copy" / "nested" / "b.txt").read_text(encoding="utf-8"), "B")
+
+    def test_duplicate_collision_resolution_for_files_and_directories(self) -> None:
+        (self.root / "report.txt").write_text("R", encoding="utf-8")
+        (self.root / "report copy.txt").write_text("existing", encoding="utf-8")
+        (self.root / "report copy 2.txt").write_text("existing", encoding="utf-8")
+        (self.root / "Album").mkdir()
+        (self.root / "Album copy").mkdir()
+        (self.root / "Album copy 2").mkdir()
+
+        file_response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/report.txt"]})
+        dir_response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/Album"]})
+
+        self.assertEqual(self._wait_task(file_response.json()["task_id"])["destination"], "storage1/report copy 3.txt")
+        self.assertEqual(self._wait_task(dir_response.json()["task_id"])["destination"], "storage1/Album copy 3")
+        self.assertTrue((self.root / "report copy 3.txt").exists())
+        self.assertTrue((self.root / "Album copy 3").is_dir())
+
+    def test_duplicate_skips_top_level_macos_sidecar(self) -> None:
+        (self.root / "._note.txt").write_text("sidecar", encoding="utf-8")
+
+        response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/._note.txt"]})
+
+        self.assertEqual(response.status_code, 202)
+        detail = self._wait_task(response.json()["task_id"])
+        self.assertEqual(detail["status"], "completed")
+        self.assertEqual(detail["done_items"], 0)
+        self.assertEqual(detail["total_items"], 0)
+        self.assertFalse((self.root / "._note copy.txt").exists())
+
+    def test_duplicate_skips_macos_sidecars_inside_directory_tree(self) -> None:
+        (self.root / "docs" / "nested").mkdir(parents=True)
+        (self.root / "docs" / "keep.txt").write_text("keep", encoding="utf-8")
+        (self.root / "docs" / "._skip.txt").write_text("skip", encoding="utf-8")
+        (self.root / "docs" / "nested" / "._nested.txt").write_text("skip", encoding="utf-8")
+        (self.root / "docs" / "nested" / "real.txt").write_text("real", encoding="utf-8")
+
+        response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/docs"]})
+
+        self.assertEqual(response.status_code, 202)
+        self._wait_task(response.json()["task_id"])
+        self.assertTrue((self.root / "docs copy" / "keep.txt").exists())
+        self.assertTrue((self.root / "docs copy" / "nested" / "real.txt").exists())
+        self.assertFalse((self.root / "docs copy" / "._skip.txt").exists())
+        self.assertFalse((self.root / "docs copy" / "nested" / "._nested.txt").exists())
+
+    def test_duplicate_failure_removes_partial_directory_artifact(self) -> None:
+        (self.root / "docs").mkdir()
+        (self.root / "docs" / "a.txt").write_text("A", encoding="utf-8")
+        (self.root / "docs" / "b.txt").write_text("B", encoding="utf-8")
+        path_guard = PathGuard({"storage1": str(self.root), "storage2": str(self.root)})
+        self._set_services(path_guard=path_guard, filesystem=FailOnSecondCopyFilesystemAdapter())
+
+        response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/docs"]})
+
+        self.assertEqual(response.status_code, 202)
+        detail = self._wait_task(response.json()["task_id"])
+        self.assertEqual(detail["status"], "failed")
+        self.assertEqual(detail["error_code"], "io_error")
+        self.assertFalse((self.root / "docs copy").exists())
+
+    def test_duplicate_path_safety_stays_intact(self) -> None:
+        response = self._request("POST", "/api/files/duplicate", {"paths": ["storage1/../escape.txt"]})
+
+        self.assertEqual(response.status_code, 403)
+        self.assertEqual(response.json()["error"]["code"], "path_traversal_detected")
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/webui/backend/tests/golden/test_api_history_golden.py b/webui/backend/tests/golden/test_api_history_golden.py
index 899bb98..0c28869 100644
--- a/webui/backend/tests/golden/test_api_history_golden.py
+++ b/webui/backend/tests/golden/test_api_history_golden.py
@@ -12,7 +12,7 @@ import httpx
 
 sys.path.insert(0, str(Path(__file__).resolve().parents[3]))
 
-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.dependencies import get_archive_download_task_service, get_copy_task_service, get_duplicate_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
@@ -20,6 +20,7 @@ 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.duplicate_task_service import DuplicateTaskService
 from backend.app.services.file_ops_service import FileOpsService
 from backend.app.services.history_service import HistoryService
 from backend.app.services.move_task_service import MoveTaskService
@@ -77,6 +78,7 @@ class HistoryApiGoldenTest(unittest.TestCase):
             artifact_root=self.artifact_root,
         )
         copy_service = CopyTaskService(path_guard=self.path_guard, repository=self.task_repo, runner=runner, history_repository=self.history_repo)
+        duplicate_service = DuplicateTaskService(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)
         history_service = HistoryService(repository=self.history_repo)
@@ -90,6 +92,9 @@ class HistoryApiGoldenTest(unittest.TestCase):
         async def _override_copy_service() -> CopyTaskService:
             return copy_service
 
+        async def _override_duplicate_service() -> DuplicateTaskService:
+            return duplicate_service
+
         async def _override_move_service() -> MoveTaskService:
             return move_service
 
@@ -102,6 +107,7 @@ class HistoryApiGoldenTest(unittest.TestCase):
         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_duplicate_task_service] = _override_duplicate_service
         app.dependency_overrides[get_move_task_service] = _override_move_service
         app.dependency_overrides[get_task_service] = _override_task_service
         app.dependency_overrides[get_history_service] = _override_history_service
@@ -209,6 +215,20 @@ class HistoryApiGoldenTest(unittest.TestCase):
         self.assertEqual(history[0]['status'], 'failed')
         self.assertEqual(history[0]['error_code'], 'io_error')
 
+    def test_duplicate_completed_history_item(self) -> None:
+        (self.root1 / 'report.txt').write_text('hello', encoding='utf-8')
+
+        response = self._request('POST', '/api/files/duplicate', {'paths': ['storage1/report.txt']})
+
+        self.assertEqual(response.status_code, 202)
+        self._wait_task(response.json()['task_id'])
+
+        history = self._request('GET', '/api/history').json()['items']
+        self.assertEqual(history[0]['operation'], 'duplicate')
+        self.assertEqual(history[0]['status'], 'completed')
+        self.assertEqual(history[0]['source'], 'storage1/report.txt')
+        self.assertEqual(history[0]['destination'], 'storage1/report copy.txt')
+
     def test_single_file_download_writes_ready_history_item(self) -> None:
         (self.root1 / 'report.txt').write_text('hello download', encoding='utf-8')
 
diff --git a/webui/backend/tests/golden/test_api_tasks_golden.py b/webui/backend/tests/golden/test_api_tasks_golden.py
index ccaa171..180245a 100644
--- a/webui/backend/tests/golden/test_api_tasks_golden.py
+++ b/webui/backend/tests/golden/test_api_tasks_golden.py
@@ -263,6 +263,30 @@ class TasksApiGoldenTest(unittest.TestCase):
         self.assertEqual(body["status"], "ready")
         self.assertEqual(body["destination"], "docs.zip")
 
+    def test_get_task_detail_duplicate_completed(self) -> None:
+        self._insert_task(
+            task_id="task-duplicate",
+            operation="duplicate",
+            status="completed",
+            source="storage1/report.txt",
+            destination="storage1/report copy.txt",
+            created_at="2026-03-10T10:00:00Z",
+            started_at="2026-03-10T10:00:01Z",
+            finished_at="2026-03-10T10:00:03Z",
+            done_items=1,
+            total_items=1,
+            current_item="storage1/report.txt",
+        )
+
+        response = self._get("/api/tasks/task-duplicate")
+
+        self.assertEqual(response.status_code, 200)
+        body = response.json()
+        self.assertEqual(body["operation"], "duplicate")
+        self.assertEqual(body["status"], "completed")
+        self.assertEqual(body["done_items"], 1)
+        self.assertEqual(body["total_items"], 1)
+
     def test_get_task_detail_requested_archive_download(self) -> None:
         self._insert_task(
             task_id="task-download-requested",
diff --git a/webui/backend/tests/unit/__pycache__/test_task_repository.cpython-313.pyc b/webui/backend/tests/unit/__pycache__/test_task_repository.cpython-313.pyc
index 8de61b3..433237f 100644
Binary files a/webui/backend/tests/unit/__pycache__/test_task_repository.cpython-313.pyc and b/webui/backend/tests/unit/__pycache__/test_task_repository.cpython-313.pyc differ
diff --git a/webui/backend/tests/unit/test_task_repository.py b/webui/backend/tests/unit/test_task_repository.py
index 4abf635..ddd6a15 100644
--- a/webui/backend/tests/unit/test_task_repository.py
+++ b/webui/backend/tests/unit/test_task_repository.py
@@ -80,6 +80,18 @@ class TaskRepositoryTest(unittest.TestCase):
         self.assertEqual(task["status"], "requested")
         self.assertEqual(artifact["file_name"], "docs.zip")
 
+    def test_create_duplicate_task_is_allowed(self) -> None:
+        created = self.repo.create_task(
+            operation="duplicate",
+            source="storage1/report.txt",
+            destination="storage1/report copy.txt",
+        )
+
+        task = self.repo.get_task(created["id"])
+
+        self.assertEqual(task["operation"], "duplicate")
+        self.assertEqual(task["status"], "queued")
+
     def test_mark_cancelled_transitions_requested_download_task(self) -> None:
         created = self.repo.create_task(
             operation="download",