Fix static analysis with latest ty (#4739)

* Fix upgrade static analysis

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* Preserve concrete transport return types

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* Avoid widening transport return types

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* Model transforming transport return types

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* Exclude standalone screenshot examples from ty

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fastmcp_slim/fastmcp/mcp_config.py

@@ -45,6 +45,7 @@ from fastmcp import _install_hints
 if TYPE_CHECKING:
     from fastmcp.client.transports import (
         ClientTransport,
+        FastMCPTransport,
         SSETransport,
         StdioTransport,
         StreamableHttpTransport,
@@ -153,7 +154,7 @@ class _TransformingMCPServerMixin(BaseModel):
 
         return wrapped_mcp_server, transport
 
-    def to_transport(self) -> ClientTransport:
+    def to_transport(self) -> FastMCPTransport:
         """Get the transport for the transforming MCP server."""
         try:
             from fastmcp.client.transports import FastMCPTransport
@@ -209,7 +210,7 @@ class StdioMCPServer(BaseModel):
 
     model_config = ConfigDict(extra="allow")  # Preserve unknown fields
 
-    def to_transport(self) -> StdioTransport:
+    def to_transport(self) -> StdioTransport | FastMCPTransport:
         from fastmcp.client.transports import StdioTransport
 
         return StdioTransport(
@@ -261,7 +262,9 @@ class RemoteMCPServer(BaseModel):
         extra="allow", arbitrary_types_allowed=True
     )  # Preserve unknown fields
 
-    def to_transport(self) -> StreamableHttpTransport | SSETransport:
+    def to_transport(
+        self,
+    ) -> StreamableHttpTransport | SSETransport | FastMCPTransport:
         from fastmcp.client.transports import (
             SSETransport,
             StreamableHttpTransport,

pyproject.toml

@@ -157,6 +157,8 @@ exclude = [
     "examples/smart_home",              # needs phue
     "examples/apps/qr_server",          # needs qrcode
     "examples/providers/sqlite",        # needs aiosqlite
+    "examples/fastmcp_config_demo",     # needs pyautogui, Pillow
+    "examples/screenshot.py",           # needs pyautogui, Pillow
     "examples/memory.py",               # needs asyncpg, numpy, pydantic_ai, pgvector
     "examples/get_file.py",             # needs aiohttp
 ]
@@ -165,9 +167,8 @@ exclude = [
 python-version = "3.10"
 
 [tool.ty.analysis]
-# prefab_ui is the apps SDK; pyautogui/PIL are optional runtime deps used only
+# prefab_ui is the apps SDK and is not installed here.
-# inside example tool bodies (screenshot demos) and are not installed here.
+replace-imports-with-any = ["prefab_ui.**"]
-replace-imports-with-any = ["prefab_ui.**", "pyautogui", "PIL", "PIL.**"]
 
 [tool.ty.rules]
 division-by-zero = "warn"

tests/test_mcp_config.py

@@ -96,7 +96,7 @@ class InMemoryStdioMCPServer(StdioMCPServer):
     mcp: FastMCP
     command: str = "in-memory"
 
-    def to_transport(self) -> FastMCPTransport:  # ty: ignore[invalid-method-override]
+    def to_transport(self) -> FastMCPTransport:
         return FastMCPTransport(mcp=self.mcp)