Skip to content

Harden MCP tools: batch exceptions, gesture null params, capabilities message #144

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
rmarinho merged 2 commits into from
Apr 24, 2026
Merged

Harden MCP tools: batch exceptions, gesture null params, capabilities message #144

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
5216a5d
Harden MCP tools: batch exception handling, gesture null params, capa…
jfversluis Apr 24, 2026
f338e5b
Address review feedback: ScrollAsync nulls, OperationCanceledExceptio…
jfversluis Apr 24, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion src/Cli/Microsoft.Maui.Cli/DevFlow/Mcp/Tools/AgentTools.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,7 @@ public static async Task<string> Capabilities(
var agent = await session.GetAgentClientAsync(agentPort);
var capabilities = await agent.GetCapabilitiesAsync();
if (capabilities.ValueKind == System.Text.Json.JsonValueKind.Undefined)
return "Agent not responding. Is the app running?";
return "Unable to retrieve capabilities. The agent may not be running, or may not support this feature (older version).";
return CliJson.SerializeUntyped(capabilities, indented: false);
}

Expand Down
13 changes: 10 additions & 3 deletions src/Cli/Microsoft.Maui.Cli/DevFlow/Mcp/Tools/BatchTools.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,8 +66,15 @@ public static async Task<string> Batch(
actions.Add(obj);
}

var agent = await session.GetAgentClientAsync(agentPort);
var result = await agent.BatchAsync(actions, continueOnError);
return CliJson.SerializeUntyped(result, indented: false);
try
{
var agent = await session.GetAgentClientAsync(agentPort);
var result = await agent.BatchAsync(actions, continueOnError);
return CliJson.SerializeUntyped(result, indented: false);
}
catch (Exception ex) when (ex is HttpRequestException or OperationCanceledException or System.Text.Json.JsonException)
{
return $"Batch request failed: {ex.Message}. Verify the app is running and the agent supports the batch endpoint.";
}
}
}
35 changes: 21 additions & 14 deletions src/DevFlow/Microsoft.Maui.DevFlow.Driver/AgentClient.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -169,14 +169,17 @@ public async Task<bool> KeyAsync(string key, string? elementId = null, string? t

public async Task<bool> GestureAsync(string type, string? elementId = null, string? direction = null, double? distance = null, int? durationMs = null)
{
return await PostActionAsync($"{UiApi}/actions/gesture", new JsonObject
var payload = new JsonObject
{
["elementId"] = elementId,
["type"] = type,
["direction"] = direction,
["distance"] = distance,
["durationMs"] = durationMs
});
["type"] = type
};

if (elementId is not null) payload["elementId"] = elementId;
if (direction is not null) payload["direction"] = direction;
if (distance.HasValue) payload["distance"] = distance.Value;
if (durationMs.HasValue) payload["durationMs"] = durationMs.Value;

Comment thread
jfversluis marked this conversation as resolved.
return await PostActionAsync($"{UiApi}/actions/gesture", payload);
Comment on lines 170 to +182
Copy link

Copilot AI Apr 24, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This change fixes a real serialization/deserialization issue (null distance/durationMs breaks the agent’s non-nullable DTO), but it isn’t covered by tests. There are existing AgentClient HTTP-shape tests (e.g., Tap/Fill/Batch) in Microsoft.Maui.DevFlow.Tests; please add a similar test for GestureAsync verifying that when distance/durationMs are null they are omitted from the POST body (and included when provided).

Copilot uses AI. Check for mistakes.
}

public async Task<JsonElement> BatchAsync(IEnumerable<JsonObject> actions, bool continueOnError = false)
Expand Down Expand Up @@ -204,16 +207,20 @@ public async Task<bool> ScrollAsync(string? elementId = null, double deltaX = 0,
{
var url = $"{UiApi}/actions/scroll";
if (window != null) url += $"?window={window}";
return await PostActionAsync(url, new JsonObject

var payload = new JsonObject
{
["elementId"] = elementId,
["deltaX"] = deltaX,
["deltaY"] = deltaY,
["animated"] = animated,
["itemIndex"] = itemIndex,
["groupIndex"] = groupIndex,
["scrollToPosition"] = scrollToPosition
});
["animated"] = animated
};

if (elementId is not null) payload["elementId"] = elementId;
if (itemIndex.HasValue) payload["itemIndex"] = itemIndex.Value;
if (groupIndex.HasValue) payload["groupIndex"] = groupIndex.Value;
if (scrollToPosition is not null) payload["scrollToPosition"] = scrollToPosition;

return await PostActionAsync(url, payload);
}

/// <summary>
Expand Down
Loading