Cover Context.headers and resolver schema-only paths

The headers property's request-present branch and the schema-inspection
helpers in the resolver tests were not exercised, breaking the 100% coverage
gate. Add direct Context.headers tests and mark the never-run helper bodies.

Author: Kludex

tests/server/mcpserver/test_resolve.py

@@ -222,13 +222,13 @@ async def never(context: ClientRequestContext, params: ElicitRequestParams) -> E
 
 def test_resolved_params_absent_from_input_schema():
     async def login(ctx: Context) -> Login:
-        return Login(username="x")
+        return Login(username="x")  # pragma: no cover - only the schema is inspected
 
     async def tool(
         repo: Annotated[str, Field(description="repo name")],
         login: Annotated[Login, Resolve(login)],
     ) -> str:
-        return repo
+        return repo  # pragma: no cover - only the schema is inspected
 
     built = Tool.from_function(tool)
     properties = built.parameters["properties"]

tests/server/mcpserver/test_server.py

@@ -1,5 +1,6 @@
 import base64
 from pathlib import Path
+from types import SimpleNamespace
 from typing import Any
 from unittest.mock import AsyncMock, MagicMock, patch
 
@@ -1547,6 +1548,27 @@ async def test_report_progress_passes_related_request_id():
     )
 
 
+def _request_context(request: object | None) -> ServerRequestContext[None, object]:
+    return ServerRequestContext(
+        session=AsyncMock(),
+        method="tools/call",
+        lifespan_context=None,
+        protocol_version="2025-11-25",
+        request=request,
+    )
+
+
+def test_context_headers_returns_request_headers():
+    request = SimpleNamespace(headers={"x-github-user": "octocat"})
+    ctx = Context(request_context=_request_context(request), mcp_server=MagicMock())
+    assert ctx.headers == {"x-github-user": "octocat"}
+
+
+def test_context_headers_is_none_without_request():
+    ctx = Context(request_context=_request_context(None), mcp_server=MagicMock())
+    assert ctx.headers is None
+
+
 async def test_read_resource_template_error():
     """Template-creation failure must surface as INTERNAL_ERROR, not INVALID_PARAMS (not-found)."""
     mcp = MCPServer()