fix(mcp): accept signed coordinates on secondary displays

Core/PeekabooCore/Sources/PeekabooAgentRuntime/MCP/Tools/DragTool+Resolution.swift

@@ -72,15 +72,10 @@ extension DragTool {
                 message: "Invalid \(parameterName) coordinates. Both x and y must be valid numbers")
         }
 
-        // Coordinates outside the desktop are nearly always malformed tool input.
-        guard background || (x >= 0 && y >= 0) else {
+        // Displays left of or above the primary display have negative global coordinates.
+        guard background || ((-20000...20000).contains(x) && (-20000...20000).contains(y)) else {
             throw CoordinateParseError(
-                message: "Invalid \(parameterName) coordinates. Both x and y must be non-negative")
-        }
-
-        guard background || (x <= 20000 && y <= 20000) else {
-            throw CoordinateParseError(
-                message: "Invalid \(parameterName) coordinates. Both x and y must be 20000 or less")
+                message: "Invalid \(parameterName) coordinates. Both x and y must be between -20000 and 20000")
         }
 
         return CGPoint(x: x, y: y)

Core/PeekabooCore/Sources/PeekabooAgentRuntime/MCP/Tools/MoveTool+Parsing.swift

@@ -15,12 +15,9 @@ extension MoveTool {
             throw CoordinateParseError(message: "Invalid \(parameterName). Both x and y must be valid numbers")
         }
 
-        guard x >= 0, y >= 0 else {
-            throw CoordinateParseError(message: "Invalid \(parameterName). Both x and y must be non-negative")
-        }
-
-        guard x <= 20000, y <= 20000 else {
-            throw CoordinateParseError(message: "Invalid \(parameterName). Both x and y must be 20000 or less")
+        guard (-20000...20000).contains(x), (-20000...20000).contains(y) else {
+            throw CoordinateParseError(
+                message: "Invalid \(parameterName). Both x and y must be between -20000 and 20000")
         }
 
         return CGPoint(x: x, y: y)

Core/PeekabooCore/Tests/PeekabooTests/MCP/MCPSecondaryDisplayPointerTests.swift

@@ -0,0 +1,49 @@
+import CoreGraphics
+import MCP
+import PeekabooAutomationKit
+import TachikomaMCP
+import Testing
+@testable import PeekabooAgentRuntime
+@testable import PeekabooAutomation
+@testable import PeekabooCore
+
+@MainActor
+struct MCPSecondaryDisplayPointerTests {
+    @Test(arguments: ["-100,200", "100,-200", "-100,-200"])
+    func `move accepts signed global coordinates for secondary displays`(_ coordinates: String) async throws {
+        let automation = MockAutomationService(accessibilityGranted: true)
+        let context = await MCPToolTestHelpers.makeLegacyContext(automation: automation)
+        let response = try await MoveTool(context: context).execute(arguments: ToolArguments(raw: [
+            "to": coordinates, "foreground": true,
+        ]))
+        #expect(!response.isError)
+        #expect(automation.lastMoveTarget != nil)
+        print("MoveTool signed target=\(coordinates); isError=\(response.isError)")
+    }
+
+    @Test
+    func `foreground drag accepts endpoints left of and above the primary display`() async throws {
+        let automation = MockAutomationService(accessibilityGranted: true)
+        let context = await MCPToolTestHelpers.makeLegacyContext(automation: automation)
+        let response = try await DragTool(context: context).execute(arguments: ToolArguments(raw: [
+            "from_coords": "-100,200", "to_coords": "100,-200", "foreground": true,
+        ]))
+        #expect(!response.isError)
+        print("DragTool signed endpoints=-100,200 to100,-200; isError=\(response.isError)")
+    }
+
+    @Test(arguments: ["-20001,1", "1,-20001", "20001,1", "nan,1", "inf,1"])
+    func `malformed or extreme foreground coordinates are refused`(_ coordinates: String) async throws {
+        let automation = MockAutomationService(accessibilityGranted: true)
+        let context = await MCPToolTestHelpers.makeLegacyContext(automation: automation)
+        let move = try await MoveTool(context: context).execute(arguments: ToolArguments(raw: [
+            "to": coordinates, "foreground": true,
+        ]))
+        let drag = try await DragTool(context: context).execute(arguments: ToolArguments(raw: [
+            "from_coords": "0,0", "to_coords": coordinates, "foreground": true,
+        ]))
+        #expect(move.isError)
+        #expect(drag.isError)
+        #expect(automation.lastMoveTarget == nil)
+    }
+}