Add deps and make linter happy

Author: vladimir-litvinchik

.github/workflows/ci.yml

@@ -66,10 +66,20 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y --no-install-recommends \
               libgdiplus \
+              libc6-dev \
               libfontconfig1 \
               fontconfig \
               fonts-dejavu \
               fonts-liberation
+          # Ubuntu installs libgdiplus as `libgdiplus.so.0` only — .NET's
+          # System.Drawing.Common dlopen()s `libgdiplus` (no version suffix)
+          # and fails with "Type initializer for 'Gdip' threw an exception"
+          # without this alias. Idempotent: the package may install the
+          # symlink directly on some releases.
+          if [ ! -e /usr/lib/x86_64-linux-gnu/libgdiplus.so ]; then
+            sudo ln -s /usr/lib/x86_64-linux-gnu/libgdiplus.so.0 \
+                       /usr/lib/x86_64-linux-gnu/libgdiplus.so
+          fi
 
       - run: pip install -e ".[dev]"
 

pyproject.toml

@@ -79,11 +79,13 @@ select = ["E", "F", "W", "I", "N", "UP", "B", "A", "C4", "SIM", "RUF"]
 ignore = ["E501"]
 
 [tool.ruff.lint.per-file-ignores]
-# Typer's CLI pattern requires `typer.Option(...)` and `Path.cwd()` as
-# argument defaults — that's the canonical usage from the Typer docs.
-# B008 ("function call in default") is incompatible with the framework
-# here, not a real bug.
-"src/groupdocs_viewer_ui/cli.py" = ["B008"]
+# cli.py:
+#   B008 — Typer's canonical pattern uses `typer.Option(...)` and `Path.cwd()`
+#          as argument defaults; the rule is incompatible with the framework.
+#   UP045 — Typer calls `typing.get_type_hints()` to introspect the signature,
+#          which fails on Python 3.9 for PEP-604 `X | None` syntax. Forced to
+#          stay on `Optional[X]` until the 3.9 floor moves.
+"src/groupdocs_viewer_ui/cli.py" = ["B008", "UP045"]
 
 [tool.mypy]
 python_version = "3.9"

src/groupdocs_viewer_ui/cache/redis.py

@@ -37,13 +37,17 @@ def __init__(
                     "RedisCache needs redis-py — install with "
                     "`pip install groupdocs-viewer-net-ui[redis]`."
                 ) from exc
-            client = redis.from_url(url)  # type: ignore[no-untyped-call]
+            # redis-py types vary by version — pair the suppression with
+            # `unused-ignore` so this works whether or not the installed
+            # release exposes a typed `from_url`.
+            client = redis.from_url(url)  # type: ignore[no-untyped-call, unused-ignore]
         self._redis = client
         self._prefix = key_prefix
 
     async def try_get(self, cache_key: str, file_path: str) -> bytes | None:
-        # redis-py is fully untyped at runtime; .get returns Any.
-        return await self._redis.get(self._key(cache_key, file_path))  # type: ignore[no-any-return]
+        # Same cross-version dance as the constructor: .get() may or may
+        # not have a typed return depending on the installed redis-py.
+        return await self._redis.get(self._key(cache_key, file_path))  # type: ignore[no-any-return, unused-ignore]
 
     async def set(self, cache_key: str, file_path: str, data: bytes) -> None:
         await self._redis.set(self._key(cache_key, file_path), data)

src/groupdocs_viewer_ui/cli.py

@@ -3,6 +3,7 @@
 
 import sys
 from pathlib import Path
+from typing import Optional
 
 import typer
 import uvicorn
@@ -29,7 +30,11 @@ def serve(
         "-f",
         help="Directory containing documents to browse and view.",
     ),
-    cache: Path | None = typer.Option(
+    # Optional[Path] (not `Path | None`) because Typer calls
+    # ``typing.get_type_hints()`` to introspect the signature, and PEP-604
+    # union syntax fails to evaluate on Python 3.9. ``eval_type_backport``
+    # only patches pydantic, not typing in general.
+    cache: Optional[Path] = typer.Option(
         None,
         "--cache",
         "-c",