Merge branch 'main' into fix/prevent-session-hang

Author: newbiehwang

.github/workflows/shared.yml

@@ -70,6 +70,7 @@ jobs:
       - name: Run pytest with coverage
         shell: bash
         run: |
+          uv run --frozen --no-sync coverage erase
           uv run --frozen --no-sync coverage run -m pytest -n auto
           uv run --frozen --no-sync coverage combine
           uv run --frozen --no-sync coverage report

CLAUDE.md

@@ -28,9 +28,19 @@ This document contains critical information about working with this codebase. Fo
    - Bug fixes require regression tests
    - IMPORTANT: The `tests/client/test_client.py` is the most well designed test file. Follow its patterns.
    - IMPORTANT: Be minimal, and focus on E2E tests: Use the `mcp.client.Client` whenever possible.
-   - IMPORTANT: Before pushing, verify 100% branch coverage on changed files by running
-     `uv run --frozen pytest -x` (coverage is configured in `pyproject.toml` with `fail_under = 100`
-     and `branch = true`). If any branch is uncovered, add a test for it before pushing.
+   - Coverage: CI requires 100% (`fail_under = 100`, `branch = true`).
+     - Full check: `./scripts/test` (~20s, matches CI exactly)
+     - Targeted check while iterating:
+
+       ```bash
+       uv run --frozen coverage erase
+       uv run --frozen coverage run -m pytest tests/path/test_foo.py
+       uv run --frozen coverage combine
+       uv run --frozen coverage report --include='src/mcp/path/foo.py' --fail-under=0
+       ```
+
+       Partial runs can't hit 100% (coverage tracks `tests/` too), so `--fail-under=0`
+       and `--include` scope the report to what you actually changed.
    - Avoid `anyio.sleep()` with a fixed duration to wait for async operations. Instead:
      - Use `anyio.Event` — set it in the callback/handler, `await event.wait()` in the test
      - For stream messages, use `await stream.receive()` instead of `sleep()` + `receive_nowait()`

README.v2.md

@@ -346,13 +346,12 @@ Tools can optionally receive a Context object by including a parameter with the
 <!-- snippet-source examples/snippets/servers/tool_progress.py -->
 ```python
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 
 mcp = MCPServer(name="Progress Example")
 
 
 @mcp.tool()
-async def long_running_task(task_name: str, ctx: Context[ServerSession, None], steps: int = 5) -> str:
+async def long_running_task(task_name: str, ctx: Context, steps: int = 5) -> str:
     """Execute a task with progress updates."""
     await ctx.info(f"Starting: {task_name}")
 
@@ -694,13 +693,12 @@ The Context object provides the following capabilities:
 <!-- snippet-source examples/snippets/servers/tool_progress.py -->
 ```python
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 
 mcp = MCPServer(name="Progress Example")
 
 
 @mcp.tool()
-async def long_running_task(task_name: str, ctx: Context[ServerSession, None], steps: int = 5) -> str:
+async def long_running_task(task_name: str, ctx: Context, steps: int = 5) -> str:
     """Execute a task with progress updates."""
     await ctx.info(f"Starting: {task_name}")
 
@@ -826,7 +824,6 @@ import uuid
 from pydantic import BaseModel, Field
 
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 from mcp.shared.exceptions import UrlElicitationRequiredError
 from mcp.types import ElicitRequestURLParams
 
@@ -844,7 +841,7 @@ class BookingPreferences(BaseModel):
 
 
 @mcp.tool()
-async def book_table(date: str, time: str, party_size: int, ctx: Context[ServerSession, None]) -> str:
+async def book_table(date: str, time: str, party_size: int, ctx: Context) -> str:
     """Book a table with date availability check.
 
     This demonstrates form mode elicitation for collecting non-sensitive user input.
@@ -868,7 +865,7 @@ async def book_table(date: str, time: str, party_size: int, ctx: Context[ServerS
 
 
 @mcp.tool()
-async def secure_payment(amount: float, ctx: Context[ServerSession, None]) -> str:
+async def secure_payment(amount: float, ctx: Context) -> str:
     """Process a secure payment requiring URL confirmation.
 
     This demonstrates URL mode elicitation using ctx.elicit_url() for
@@ -892,7 +889,7 @@ async def secure_payment(amount: float, ctx: Context[ServerSession, None]) -> st
 
 
 @mcp.tool()
-async def connect_service(service_name: str, ctx: Context[ServerSession, None]) -> str:
+async def connect_service(service_name: str, ctx: Context) -> str:
     """Connect to a third-party service requiring OAuth authorization.
 
     This demonstrates the "throw error" pattern using UrlElicitationRequiredError.
@@ -933,14 +930,13 @@ Tools can interact with LLMs through sampling (generating text):
 <!-- snippet-source examples/snippets/servers/sampling.py -->
 ```python
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 from mcp.types import SamplingMessage, TextContent
 
 mcp = MCPServer(name="Sampling Example")
 
 
 @mcp.tool()
-async def generate_poem(topic: str, ctx: Context[ServerSession, None]) -> str:
+async def generate_poem(topic: str, ctx: Context) -> str:
     """Generate a poem using LLM sampling."""
     prompt = f"Write a short poem about {topic}"
 
@@ -970,13 +966,12 @@ Tools can send logs and notifications through the context:
 <!-- snippet-source examples/snippets/servers/notifications.py -->
 ```python
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 
 mcp = MCPServer(name="Notifications Example")
 
 
 @mcp.tool()
-async def process_data(data: str, ctx: Context[ServerSession, None]) -> str:
+async def process_data(data: str, ctx: Context) -> str:
     """Process data with logging."""
     # Different log levels
     await ctx.debug(f"Debug: Processing '{data}'")

examples/servers/everything-server/mcp_everything_server/server.py

@@ -13,7 +13,6 @@
 from mcp.server import ServerRequestContext
 from mcp.server.mcpserver import Context, MCPServer
 from mcp.server.mcpserver.prompts.base import UserMessage
-from mcp.server.session import ServerSession
 from mcp.server.streamable_http import EventCallback, EventMessage, EventStore
 from mcp.types import (
     AudioContent,
@@ -142,7 +141,7 @@ def test_multiple_content_types() -> list[TextContent | ImageContent | EmbeddedR
 
 
 @mcp.tool()
-async def test_tool_with_logging(ctx: Context[ServerSession, None]) -> str:
+async def test_tool_with_logging(ctx: Context) -> str:
     """Tests tool that emits log messages during execution"""
     await ctx.info("Tool execution started")
     await asyncio.sleep(0.05)
@@ -155,7 +154,7 @@ async def test_tool_with_logging(ctx: Context[ServerSession, None]) -> str:
 
 
 @mcp.tool()
-async def test_tool_with_progress(ctx: Context[ServerSession, None]) -> str:
+async def test_tool_with_progress(ctx: Context) -> str:
     """Tests tool that reports progress notifications"""
     await ctx.report_progress(progress=0, total=100, message="Completed step 0 of 100")
     await asyncio.sleep(0.05)
@@ -173,7 +172,7 @@ async def test_tool_with_progress(ctx: Context[ServerSession, None]) -> str:
 
 
 @mcp.tool()
-async def test_sampling(prompt: str, ctx: Context[ServerSession, None]) -> str:
+async def test_sampling(prompt: str, ctx: Context) -> str:
     """Tests server-initiated sampling (LLM completion request)"""
     try:
         # Request sampling from client
@@ -198,7 +197,7 @@ class UserResponse(BaseModel):
 
 
 @mcp.tool()
-async def test_elicitation(message: str, ctx: Context[ServerSession, None]) -> str:
+async def test_elicitation(message: str, ctx: Context) -> str:
     """Tests server-initiated elicitation (user input request)"""
     try:
         # Request user input from client
@@ -230,7 +229,7 @@ class SEP1034DefaultsSchema(BaseModel):
 
 
 @mcp.tool()
-async def test_elicitation_sep1034_defaults(ctx: Context[ServerSession, None]) -> str:
+async def test_elicitation_sep1034_defaults(ctx: Context) -> str:
     """Tests elicitation with default values for all primitive types (SEP-1034)"""
     try:
         # Request user input with defaults for all primitive types
@@ -289,7 +288,7 @@ class EnumSchemasTestSchema(BaseModel):
 
 
 @mcp.tool()
-async def test_elicitation_sep1330_enums(ctx: Context[ServerSession, None]) -> str:
+async def test_elicitation_sep1330_enums(ctx: Context) -> str:
     """Tests elicitation with enum schema variations per SEP-1330"""
     try:
         result = await ctx.elicit(
@@ -313,7 +312,7 @@ def test_error_handling() -> str:
 
 
 @mcp.tool()
-async def test_reconnection(ctx: Context[ServerSession, None]) -> str:
+async def test_reconnection(ctx: Context) -> str:
     """Tests SSE polling by closing stream mid-call (SEP-1699)"""
     await ctx.info("Before disconnect")
 

examples/snippets/servers/elicitation.py

@@ -10,7 +10,6 @@
 from pydantic import BaseModel, Field
 
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 from mcp.shared.exceptions import UrlElicitationRequiredError
 from mcp.types import ElicitRequestURLParams
 
@@ -28,7 +27,7 @@ class BookingPreferences(BaseModel):
 
 
 @mcp.tool()
-async def book_table(date: str, time: str, party_size: int, ctx: Context[ServerSession, None]) -> str:
+async def book_table(date: str, time: str, party_size: int, ctx: Context) -> str:
     """Book a table with date availability check.
 
     This demonstrates form mode elicitation for collecting non-sensitive user input.
@@ -52,7 +51,7 @@ async def book_table(date: str, time: str, party_size: int, ctx: Context[ServerS
 
 
 @mcp.tool()
-async def secure_payment(amount: float, ctx: Context[ServerSession, None]) -> str:
+async def secure_payment(amount: float, ctx: Context) -> str:
     """Process a secure payment requiring URL confirmation.
 
     This demonstrates URL mode elicitation using ctx.elicit_url() for
@@ -76,7 +75,7 @@ async def secure_payment(amount: float, ctx: Context[ServerSession, None]) -> st
 
 
 @mcp.tool()
-async def connect_service(service_name: str, ctx: Context[ServerSession, None]) -> str:
+async def connect_service(service_name: str, ctx: Context) -> str:
     """Connect to a third-party service requiring OAuth authorization.
 
     This demonstrates the "throw error" pattern using UrlElicitationRequiredError.

examples/snippets/servers/notifications.py

@@ -1,11 +1,10 @@
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 
 mcp = MCPServer(name="Notifications Example")
 
 
 @mcp.tool()
-async def process_data(data: str, ctx: Context[ServerSession, None]) -> str:
+async def process_data(data: str, ctx: Context) -> str:
     """Process data with logging."""
     # Different log levels
     await ctx.debug(f"Debug: Processing '{data}'")

examples/snippets/servers/sampling.py

@@ -1,12 +1,11 @@
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 from mcp.types import SamplingMessage, TextContent
 
 mcp = MCPServer(name="Sampling Example")
 
 
 @mcp.tool()
-async def generate_poem(topic: str, ctx: Context[ServerSession, None]) -> str:
+async def generate_poem(topic: str, ctx: Context) -> str:
     """Generate a poem using LLM sampling."""
     prompt = f"Write a short poem about {topic}"
 

examples/snippets/servers/tool_progress.py

@@ -1,11 +1,10 @@
 from mcp.server.mcpserver import Context, MCPServer
-from mcp.server.session import ServerSession
 
 mcp = MCPServer(name="Progress Example")
 
 
 @mcp.tool()
-async def long_running_task(task_name: str, ctx: Context[ServerSession, None], steps: int = 5) -> str:
+async def long_running_task(task_name: str, ctx: Context, steps: int = 5) -> str:
     """Execute a task with progress updates."""
     await ctx.info(f"Starting: {task_name}")
 

scripts/test

@@ -2,6 +2,7 @@
 
 set -ex
 
+uv run --frozen coverage erase
 uv run --frozen coverage run -m pytest -n auto $@
 uv run --frozen coverage combine
 uv run --frozen coverage report

src/mcp/server/lowlevel/server.py

@@ -414,11 +414,6 @@ async def _handle_message(
                         )
                 case Exception():
                     logger.error(f"Received exception from stream: {message}")
-                    await session.send_log_message(
-                        level="error",
-                        data="Internal Server Error",
-                        logger="mcp.server.exception_handler",
-                    )
                     if raise_exceptions:
                         raise message
                 case _: