Label MCP tool calls in tool group summaries

A tool the registry does not hold was counted as a command, so a turn's
MCP calls showed up as "2 commands" in its tool group summary and as
commands started in the status line.

Every MCP tool name has the mcp_ prefix, so those calls now have their
own activity kind. The summary reads "1 MCP call" or "2 MCP calls", and
the status line counts MCP calls made.

src/core/app/app_worker_runtime.zig

@@ -1338,6 +1338,7 @@ pub fn Runtime(comptime App: type) type {
                 .open => stream.open_count += 1,
                 .command => stream.command_count += 1,
                 .subagent => stream.subagent_count += 1,
+                .mcp => stream.mcp_count += 1,
                 .ask => {},
             }
         }

src/core/output/activity_status.zig

@@ -99,6 +99,7 @@ fn streamStatusVerb(stream: StreamState) []const u8 {
         .subagent => "delegating",
         .open => "opening",
         .ask => "asking",
+        .mcp => "calling",
     };
 }
 
@@ -231,7 +232,7 @@ fn buildThinkingLabelFull(buf: []u8, stream: StreamState) []const u8 {
     return out.buffered();
 }
 
-fn activityParts(stream: StreamState) [7]ActivityPart {
+fn activityParts(stream: StreamState) [8]ActivityPart {
     return .{
         .{ .count = stream.read_count, .singular = "file", .plural = "files", .verb = "read" },
         .{ .count = stream.list_count, .singular = "directory", .plural = "directories", .verb = "listed" },
@@ -240,6 +241,7 @@ fn activityParts(stream: StreamState) [7]ActivityPart {
         .{ .count = stream.command_count, .singular = "command", .plural = "commands", .verb = "started" },
         .{ .count = stream.subagent_count, .singular = "subagent", .plural = "subagents", .verb = "created" },
         .{ .count = stream.open_count, .singular = "file", .plural = "files", .verb = "opened" },
+        .{ .count = stream.mcp_count, .singular = "MCP call", .plural = "MCP calls", .verb = "made" },
     };
 }
 

src/core/shared/types.zig

@@ -290,6 +290,7 @@ pub const StreamState = struct {
     open_count: usize = 0,
     command_count: usize = 0,
     subagent_count: usize = 0,
+    mcp_count: usize = 0,
     token_progress: TurnTokenProgress = .{},
     last_activity_kind: ?ToolActivityKind = null,
     /// When the turn started; 0 hides the elapsed counter and activity blink.
@@ -2476,6 +2477,8 @@ pub const ToolActivityKind = enum {
     command,
     subagent,
     ask,
+    /// A call to an MCP server's tool.
+    mcp,
 };
 
 pub const QuestionOption = struct {

src/core/tooling/tool_dispatch.zig

@@ -568,7 +568,13 @@ pub fn dispatchRunCommandCompatibility(
 }
 
 pub fn toolActivityKind(registry: Registry, tool_name: []const u8) core_types.ToolActivityKind {
-    return if (registry.lookup(tool_name)) |tool| tool.activity_kind else .command;
+    return if (registry.lookup(tool_name)) |tool| tool.activity_kind else unregisteredActivityKind(tool_name);
+}
+
+/// A name the registry does not hold is an MCP server's tool when it has the
+/// `mcp_` prefix every MCP tool name gets, and is otherwise treated as a command.
+fn unregisteredActivityKind(tool_name: []const u8) core_types.ToolActivityKind {
+    return if (std.mem.startsWith(u8, tool_name, "mcp_")) .mcp else .command;
 }
 
 pub fn staticPresentation(tool: Tool) CallPresentation {
@@ -609,7 +615,7 @@ pub fn toolActivityKindForCall(
     call: core_types.ToolCall,
 ) core_types.ToolActivityKind {
     const presentation = toolCallPresentation(alloc, registry, call) orelse
-        return .command;
+        return unregisteredActivityKind(call.name);
     return presentation.activity_kind;
 }
 

src/ui/transcript/tool_group_projection.zig

@@ -149,8 +149,10 @@ const category_labels = [_][]const u8{
     "command",
     "subagent",
     "browser",
+    "MCP call",
 };
 const command_category_index = 5;
+const mcp_category_index = 8;
 
 const Summary = struct {
     total: usize = 0,
@@ -184,6 +186,7 @@ fn categoryIndex(kind: types.ToolActivityKind) ?usize {
         .command => command_category_index,
         .subagent => 6,
         .ask => null,
+        .mcp => mcp_category_index,
     };
 }
 
@@ -531,10 +534,13 @@ fn formatGroupSummary(alloc: std.mem.Allocator, summary: Summary) ![]u8 {
         const index = next_index orelse break;
         emitted[index] = true;
         const count = summary.categories[index];
-        const label = if (index == command_category_index and count != 1)
-            "commands"
-        else
-            category_labels[index];
+        const label = if (count == 1)
+            category_labels[index]
+        else switch (index) {
+            command_category_index => "commands",
+            mcp_category_index => "MCP calls",
+            else => category_labels[index],
+        };
         try appendSegment(&out.writer, count, label);
     }
     try appendSegment(&out.writer, summary.completion_unreported, "unreported");