fix(features): defer unknown client availability

Apply pre-feature protocol and elicitation filtering only when stateless request metadata is known, leaving existing middleware to enforce unknown contexts.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 1e4a1ca6-53f7-4158-af22-35d2448d0b13

Author: SamMorrowDrums

pkg/inventory/filters.go

@@ -61,10 +61,12 @@ func (r *Inventory) isToolEnabled(ctx context.Context, tool *ServerTool, feature
 		return false
 	}
 	if availability := tool.availability(); !availability.unrestricted() {
-		if info, ok := ghcontext.MCPMethod(ctx); ok &&
-			(info.Method == MCPMethodToolsList || info.Method == MCPMethodToolsCall) &&
-			!toolAvailable(info.ProtocolVersion, info.ClientCapabilities, availability) {
-			return false
+		if info, ok := ghcontext.MCPMethod(ctx); ok && (info.Method == MCPMethodToolsList || info.Method == MCPMethodToolsCall) {
+			known := (availability.minimumProtocolVersion == "" || info.ProtocolVersion != "") &&
+				(availability.requiredElicitationMode == "" || info.ClientCapabilities != nil)
+			if known && !toolAvailable(info.ProtocolVersion, info.ClientCapabilities, availability) {
+				return false
+			}
 		}
 	}
 	// 4. Check feature availability.

pkg/inventory/registry_test.go

@@ -1959,6 +1959,11 @@ func TestMCPAvailabilityRunsBeforeFeatureChecks(t *testing.T) {
 			})
 			require.Len(t, inv.AvailableTools(ctx), 2)
 			require.Equal(t, 1, calls)
+
+			calls = 0
+			ctx = ghcontext.WithMCPMethodInfo(context.Background(), &ghcontext.MCPMethodInfo{Method: method})
+			require.Len(t, inv.AvailableTools(ctx), 2)
+			require.Equal(t, 1, calls)
 		})
 	}
 }