feat: file viewer added

webui/backend/app/api/routes_files.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 from fastapi import APIRouter, Depends
 
-from backend.app.api.schemas import DeleteRequest, DeleteResponse, MkdirRequest, MkdirResponse, RenameRequest, RenameResponse
+from backend.app.api.schemas import DeleteRequest, DeleteResponse, MkdirRequest, MkdirResponse, RenameRequest, RenameResponse, ViewResponse
 from backend.app.dependencies import get_file_ops_service
 from backend.app.services.file_ops_service import FileOpsService
 
@@ -31,3 +31,11 @@ async def delete(
     service: FileOpsService = Depends(get_file_ops_service),
 ) -> DeleteResponse:
     return service.delete(path=request.path)
+
+
+@router.get("/view", response_model=ViewResponse)
+async def view(
+    path: str,
+    service: FileOpsService = Depends(get_file_ops_service),
+) -> ViewResponse:
+    return service.view(path=path)

webui/backend/app/api/schemas.py

@@ -58,6 +58,16 @@ class DeleteResponse(BaseModel):
     path: str
 
 
+class ViewResponse(BaseModel):
+    path: str
+    name: str
+    content_type: str
+    encoding: str
+    truncated: bool
+    size: int
+    content: str
+
+
 class TaskListItem(BaseModel):
     id: str
     operation: str

webui/backend/app/fs/filesystem_adapter.py

@@ -59,3 +59,17 @@ class FilesystemAdapter:
                 if on_progress:
                     on_progress(out_f.tell())
         shutil.copystat(src, dst, follow_symlinks=False)
+
+    def read_text_preview(self, path: Path, max_bytes: int, encoding: str = "utf-8") -> dict:
+        size = int(path.stat().st_size)
+        limit = max_bytes + 1
+        with path.open("rb") as in_f:
+            raw = in_f.read(limit)
+        truncated = size > max_bytes or len(raw) > max_bytes
+        if truncated:
+            raw = raw[:max_bytes]
+        return {
+            "size": size,
+            "truncated": truncated,
+            "content": raw.decode(encoding, errors="replace"),
+        }

webui/backend/app/services/file_ops_service.py

@@ -3,10 +3,27 @@ from __future__ import annotations
 from pathlib import Path
 
 from backend.app.api.errors import AppError
-from backend.app.api.schemas import DeleteResponse, MkdirResponse, RenameResponse
+from backend.app.api.schemas import DeleteResponse, MkdirResponse, RenameResponse, ViewResponse
 from backend.app.fs.filesystem_adapter import FilesystemAdapter
 from backend.app.security.path_guard import PathGuard
 
+TEXT_PREVIEW_MAX_BYTES = 256 * 1024
+TEXT_CONTENT_TYPES = {
+    ".txt": "text/plain",
+    ".log": "text/plain",
+    ".md": "text/markdown",
+    ".yml": "text/yaml",
+    ".yaml": "text/yaml",
+    ".json": "application/json",
+    ".js": "text/javascript",
+    ".css": "text/css",
+    ".html": "text/html",
+}
+SPECIAL_TEXT_FILENAMES = {
+    "dockerfile": "text/plain",
+    "containerfile": "text/plain",
+}
+
 
 class FileOpsService:
     def __init__(self, path_guard: PathGuard, filesystem: FilesystemAdapter):
@@ -129,6 +146,64 @@ class FileOpsService:
 
         return DeleteResponse(path=resolved_target.relative)
 
+    def view(self, path: str) -> ViewResponse:
+        resolved_target = self._path_guard.resolve_existing_path(path)
+
+        if resolved_target.absolute.is_dir():
+            raise AppError(
+                code="type_conflict",
+                message="Source must be a file",
+                status_code=409,
+                details={"path": resolved_target.relative},
+            )
+        if not resolved_target.absolute.is_file():
+            raise AppError(
+                code="type_conflict",
+                message="Unsupported path type for view",
+                status_code=409,
+                details={"path": resolved_target.relative},
+            )
+
+        content_type = self._content_type_for(resolved_target.absolute)
+        if content_type is None:
+            raise AppError(
+                code="unsupported_type",
+                message="File type is not supported for preview",
+                status_code=409,
+                details={"path": resolved_target.relative},
+            )
+
+        try:
+            preview = self._filesystem.read_text_preview(
+                resolved_target.absolute,
+                max_bytes=TEXT_PREVIEW_MAX_BYTES,
+                encoding="utf-8",
+            )
+        except OSError as exc:
+            raise AppError(
+                code="io_error",
+                message="Filesystem operation failed",
+                status_code=500,
+                details={"reason": str(exc)},
+            )
+
+        return ViewResponse(
+            path=resolved_target.relative,
+            name=resolved_target.absolute.name,
+            content_type=content_type,
+            encoding="utf-8",
+            truncated=preview["truncated"],
+            size=preview["size"],
+            content=preview["content"],
+        )
+
     @staticmethod
     def _join_relative(base: str, name: str) -> str:
         return f"{base}/{name}" if base else name
+
+    @staticmethod
+    def _content_type_for(path: Path) -> str | None:
+        special_name = SPECIAL_TEXT_FILENAMES.get(path.name.lower())
+        if special_name:
+            return special_name
+        return TEXT_CONTENT_TYPES.get(path.suffix.lower())