feat: OpenMesh 基础平台与 MD/PDF 转换技能

- 后端: coworker 智能体框架, WS API, 文件上传, 附件处理
- 前端: Open WebUI, 文件全量走 upload API (含 MD/TXT/JSON 等文本类)
- 技能: md-to-office (pandoc + wkhtmltopdf)
- 修复: 上传文件路径丢失, Agent 搜索浪费, 输出文件跑到 uploads/
- 打包: PyInstaller one-dir, 预打包 pandoc/wkhtmltopdf/chromium

coworker/teams/attachments.py

@@ -0,0 +1,114 @@
+"""Content-addressed attachments for board items — screenshots first.
+
+Review artifacts don't belong in the repo (they aren't source, and they die with
+checkouts) and don't belong in the board log (events carry refs, never blobs — no
+megabytes under the hash chain). They live here: files named by their sha256 in the
+state dir, bridged into the board as a normal comment event carrying an
+`attachment://<hash>.<ext>#<name>` ref.
+
+Content addressing buys three things: dedupe for free (the same screenshot attached
+twice stores once), immutability by construction (the ref can never dangle onto
+changed bytes), and location independence — on a hosted board the same ref resolves
+to object storage instead of this directory.
+
+Scope is images-only and ~10MB to start; the allowlist is the policy choke point
+when that widens.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import re
+from pathlib import Path
+from typing import Optional
+
+from .model import BoardError, BoardNotFoundError
+
+ATTACHMENT_SCHEME = "attachment://"
+MAX_ATTACHMENT_BYTES = 10 * 1024 * 1024
+
+# Extension → mime for the types we accept. Sniffed magic must agree with the
+# claimed extension — a .png that isn't a PNG is refused, not renamed.
+_IMAGE_TYPES = {
+    "png": "image/png",
+    "jpg": "image/jpeg",
+    "jpeg": "image/jpeg",
+    "gif": "image/gif",
+    "webp": "image/webp",
+}
+
+_MAGIC = {
+    "png": b"\x89PNG\r\n\x1a\n",
+    "jpg": b"\xff\xd8\xff",
+    "jpeg": b"\xff\xd8\xff",
+    "gif": b"GIF8",
+    "webp": b"RIFF",  # RIFF….WEBP — checked with the fourcc below
+}
+
+_STORED_NAME = re.compile(r"[0-9a-f]{64}\.[a-z0-9]{1,5}")
+
+
+class AttachmentStore:
+    def __init__(self, root: str | Path) -> None:
+        self.root = Path(root).expanduser()
+
+    def put(self, data: bytes, filename: str) -> str:
+        """Store one attachment; returns its `attachment://` ref. Idempotent —
+        identical bytes land on the same file."""
+        ext = _validate(data, filename)
+        stored = f"{hashlib.sha256(data).hexdigest()}.{ext}"
+        self.root.mkdir(parents=True, exist_ok=True)
+        target = self.root / stored
+        if not target.exists():
+            tmp = target.with_suffix(target.suffix + ".tmp")
+            tmp.write_bytes(data)
+            tmp.replace(target)
+        safe_name = Path(filename).name.replace("#", "_")
+        return f"{ATTACHMENT_SCHEME}{stored}#{safe_name}"
+
+    def path_for(self, stored: str) -> Path:
+        """Resolve a stored name (`<sha256>.<ext>`) to its file. The strict name
+        check is the traversal guard — nothing else reaches the filesystem."""
+        stored = validate_stored_name(stored)
+        path = self.root / stored
+        if not path.exists():
+            raise BoardNotFoundError("attachment not found")
+        return path
+
+    def mime_for(self, stored: str) -> str:
+        return _IMAGE_TYPES.get(stored.rsplit(".", 1)[-1], "application/octet-stream")
+
+
+def stored_name(ref: str) -> Optional[str]:
+    """`attachment://<hash>.<ext>#<name>` → `<hash>.<ext>`; None for other refs."""
+    if not ref.startswith(ATTACHMENT_SCHEME):
+        return None
+    return ref[len(ATTACHMENT_SCHEME):].split("#", 1)[0]
+
+
+def validate_stored_name(stored: str) -> str:
+    """Return one normalized stored name, rejecting malformed input."""
+    stored = stored.strip()
+    if not _STORED_NAME.fullmatch(stored):
+        raise BoardError(f"not an attachment name: {stored!r}")
+    return stored
+
+
+def _validate(data: bytes, filename: str) -> str:
+    if not data:
+        raise BoardError("attachment is empty")
+    if len(data) > MAX_ATTACHMENT_BYTES:
+        raise BoardError(
+            f"attachment exceeds {MAX_ATTACHMENT_BYTES // (1024 * 1024)}MB"
+        )
+    ext = Path(filename).suffix.lstrip(".").lower()
+    if ext not in _IMAGE_TYPES:
+        raise BoardError(
+            f"unsupported attachment type .{ext or '?'} — images only for now"
+            f" ({', '.join(sorted(set(_IMAGE_TYPES)))})"
+        )
+    if not data.startswith(_MAGIC[ext]) or (
+        ext == "webp" and data[8:12] != b"WEBP"
+    ):
+        raise BoardError(f"file content does not look like .{ext}")
+    return "jpg" if ext == "jpeg" else ext