fix(dashboard): clean up upload temp file on client disconnect + pin python-multipart (NS-501)

Follow-up to #47663 (streaming multipart upload), fixing two issues that
landed with it.

1. Temp file leaked on client disconnect. The streaming upload endpoint's
   except chain caught only HTTPException / PermissionError / OSError — all
   Exception subclasses. asyncio.CancelledError, raised when a browser aborts
   a large upload mid-stream (the exact NS-501 scenario), is a BaseException,
   so it bypassed every except clause and reached a finally that only closed
   the file handle and never unlinked the temp file. Every aborted large
   upload orphaned a partial `.{name}.*.upload` file (up to ~100 MB) in the
   target directory. Cleanup now lives in finally, keyed on a `renamed`
   success flag, so the temp file is removed on every non-success exit
   including BaseException paths. Added test_stream_upload_cleans_temp_on_cancellation,
   which fails on the pre-fix code (leaks the temp file) and passes with the fix.

2. python-multipart pinned to ==0.0.27 instead of ==0.0.20. The package was
   already resolved at 0.0.27 transitively (via daytona) before #47663; the
   explicit ==0.0.20 pin in the [web] extra and the tool.dashboard lazy-install
   set downgraded it. Bumped both to ==0.0.27 and regenerated with `uv lock`,
   keeping the lockfile coherent. The base dependency stays >=0.0.9,<1.

hermes_cli/web_server.py

@@ -1529,6 +1529,7 @@ async def upload_managed_file_stream(
     )
     tmp_path = Path(tmp_name)
     total = 0
+    renamed = False
     try:
         with os.fdopen(tmp_fd, "wb") as out:
             while True:
@@ -1540,16 +1541,21 @@ async def upload_managed_file_stream(
                     raise HTTPException(status_code=413, detail="File is too large")
                 out.write(chunk)
         os.replace(tmp_path, target)
+        renamed = True
     except HTTPException:
-        tmp_path.unlink(missing_ok=True)
         raise
     except PermissionError:
-        tmp_path.unlink(missing_ok=True)
         raise HTTPException(status_code=403, detail="File is not writable")
     except OSError as exc:
-        tmp_path.unlink(missing_ok=True)
         raise HTTPException(status_code=500, detail=f"Could not write file: {exc}")
     finally:
+        # Clean up the temp file on every non-success exit, including
+        # BaseException paths the `except` clauses above don't catch — most
+        # importantly asyncio.CancelledError when a browser aborts a large
+        # upload mid-stream (the exact NS-501 scenario). os.replace clears
+        # tmp_path on success, so only unlink when the rename didn't happen.
+        if not renamed:
+            tmp_path.unlink(missing_ok=True)
         await file.close()
 
     return {

pyproject.toml

@@ -258,7 +258,7 @@ youtube = [
 # `hermes dashboard` (localhost SPA + API).  Not in core to keep the default install lean.
 # starlette==1.0.1 pinned for CVE-2026-48710 (BadHost) — fastapi pulls Starlette
 # transitively and pre-1.0.1 is the vulnerable range. See the mcp extra above.
-web = ["fastapi==0.133.1", "uvicorn[standard]==0.41.0", "starlette==1.0.1", "python-multipart==0.0.20"]
+web = ["fastapi==0.133.1", "uvicorn[standard]==0.41.0", "starlette==1.0.1", "python-multipart==0.0.27"]
 all = [
   # Policy (2026-05-12): `[all]` includes only extras that genuinely
   # CAN'T be lazy-installed via `tools/lazy_deps.py` — i.e. things every

tests/hermes_cli/test_web_server_files.py

@@ -436,3 +436,55 @@ def test_stream_upload_large_file_under_cap_succeeds(forced_files_client, monkey
     assert created.status_code == 200
     assert file_path.stat().st_size == len(payload)
     assert file_path.read_bytes() == payload
+
+
+def test_stream_upload_cleans_temp_on_cancellation(forced_files_client):
+    """A client disconnect mid-stream (asyncio.CancelledError) must not leak a temp file.
+
+    CancelledError is a BaseException, not an Exception, so it bypasses the
+    endpoint's ``except`` clauses entirely. The cleanup therefore lives in a
+    ``finally`` keyed on a success flag — without it, every aborted large
+    upload (the exact NS-501 scenario) would orphan a partial ``.upload`` temp
+    file in the target directory. We invoke the endpoint coroutine directly so
+    the BaseException propagates instead of being swallowed by the test client.
+    """
+    import asyncio
+
+    _client, root = forced_files_client
+    target = root / "out" / "aborted.bin"
+    target.parent.mkdir(parents=True, exist_ok=True)
+
+    class _AbortingUpload:
+        """UploadFile stand-in that yields one chunk then aborts like a dropped client."""
+
+        filename = "aborted.bin"
+
+        def __init__(self):
+            self._calls = 0
+
+        async def read(self, _size):
+            self._calls += 1
+            if self._calls == 1:
+                return b"partial chunk before the client vanished"
+            raise asyncio.CancelledError()
+
+        async def close(self):
+            return None
+
+    request = SimpleNamespace()
+
+    with pytest.raises(asyncio.CancelledError):
+        asyncio.run(
+            web_server.upload_managed_file_stream(
+                request=request,
+                file=_AbortingUpload(),
+                path=str(target),
+                overwrite=True,
+            )
+        )
+
+    # No partial data was promoted into place ...
+    assert not target.exists()
+    # ... and no .upload temp file was left behind.
+    leftovers = [p.name for p in target.parent.iterdir() if ".upload" in p.name]
+    assert leftovers == [], f"temp upload files leaked on cancellation: {leftovers}"

tools/lazy_deps.py

@@ -178,7 +178,7 @@ LAZY_DEPS: dict[str, tuple[str, ...]] = {
         "fastapi==0.133.1",
         "uvicorn[standard]==0.41.0",
         "starlette==1.0.1",  # CVE-2026-48710 (BadHost) — keep lazy-install in sync with pyproject [web]
-        "python-multipart==0.0.20",  # FastAPI UploadFile/Form for streaming uploads (NS-501)
+        "python-multipart==0.0.27",  # FastAPI UploadFile/Form for streaming uploads (NS-501)
     ),
     # Vision image-resize recovery (Pillow). Pillow is now a CORE dependency
     # (pyproject `dependencies`), so this entry is a belt-and-suspenders fallback

uv.lock

@@ -1713,7 +1713,7 @@ requires-dist = [
     { name = "pytest-asyncio", marker = "extra == 'dev'", specifier = "==1.3.0" },
     { name = "python-dotenv", specifier = "==1.2.2" },
     { name = "python-multipart", specifier = ">=0.0.9,<1" },
-    { name = "python-multipart", marker = "extra == 'web'", specifier = "==0.0.20" },
+    { name = "python-multipart", marker = "extra == 'web'", specifier = "==0.0.27" },
     { name = "python-telegram-bot", extras = ["webhooks"], marker = "extra == 'messaging'", specifier = "==22.6" },
     { name = "python-telegram-bot", extras = ["webhooks"], marker = "extra == 'termux'", specifier = "==22.6" },
     { name = "pywinpty", marker = "sys_platform == 'win32'", specifier = ">=2.0.0,<3" },
@@ -3317,11 +3317,11 @@ wheels = [
 
 [[package]]
 name = "python-multipart"
-version = "0.0.20"
+version = "0.0.27"
 source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/f3/87/f44d7c9f274c7ee665a29b885ec97089ec5dc034c7f3fafa03da9e39a09e/python_multipart-0.0.20.tar.gz", hash = "sha256:8dd0cab45b8e23064ae09147625994d090fa46f5b0d1e13af944c331a7fa9d13", size = 37158, upload-time = "2024-12-16T19:45:46.972Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/69/9b/f23807317a113dc36e74e75eb265a02dd1a4d9082abc3c1064acd22997c4/python_multipart-0.0.27.tar.gz", hash = "sha256:9870a6a8c5a20a5bf4f07c017bd1489006ff8836cff097b6933355ee2b49b602", size = 44043, upload-time = "2026-04-27T10:51:26.649Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/45/58/38b5afbc1a800eeea951b9285d3912613f2603bdf897a4ab0f4bd7f405fc/python_multipart-0.0.20-py3-none-any.whl", hash = "sha256:8a62d3a8335e06589fe01f2a3e178cdcc632f3fbe0d492ad9ee0ec35aab1f104", size = 24546, upload-time = "2024-12-16T19:45:44.423Z" },
+    { url = "https://files.pythonhosted.org/packages/99/78/4126abcbdbd3c559d43e0db7f7b9173fc6befe45d39a2856cc0b8ec2a5a6/python_multipart-0.0.27-py3-none-any.whl", hash = "sha256:6fccfad17a27334bd0193681b369f476eda3409f17381a2d65aa7df3f7275645", size = 29254, upload-time = "2026-04-27T10:51:24.997Z" },
 ]
 
 [[package]]