fix: compact plan and todo tool header args (#1031)

src/cli/helpers/formatArgsDisplay.ts

@@ -7,13 +7,19 @@ import {
   isFileReadTool,
   isFileWriteTool,
   isPatchTool,
+  isPlanTool,
   isShellTool,
+  isTodoTool,
 } from "./toolNameMapping.js";
 
 // Small helpers
 const isRecord = (v: unknown): v is Record<string, unknown> =>
   typeof v === "object" && v !== null;
 
+function formatItemCount(count: number): string {
+  return `${String(count)} item${count === 1 ? "" : "s"}`;
+}
+
 /**
  * Formats a file path for display (matches Claude Code style):
  * - Files within cwd: relative path without ./ prefix
@@ -280,6 +286,18 @@ export function formatArgsDisplay(
             return { display, parsed };
           }
 
+          // Plan tools: only show compact plan item count.
+          if (isPlanTool(toolName) && Array.isArray(parsed.plan)) {
+            display = formatItemCount(parsed.plan.length);
+            return { display, parsed };
+          }
+
+          // Todo tools: only show compact todo item count.
+          if (isTodoTool(toolName) && Array.isArray(parsed.todos)) {
+            display = formatItemCount(parsed.todos.length);
+            return { display, parsed };
+          }
+
           // Shell/Bash tools: show just the command
           if (isShellTool(toolName) && parsed.command) {
             // Handle both string and array command formats

src/tests/cli/formatArgsDisplay.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, test } from "bun:test";
+import { formatArgsDisplay } from "../../cli/helpers/formatArgsDisplay";
+
+describe("formatArgsDisplay compact plan/todo headers", () => {
+  test("shows only plan item count for update_plan", () => {
+    const args = JSON.stringify({
+      explanation: "Investigating restart regression",
+      plan: [
+        { step: "Step 1", status: "pending" },
+        { step: "Step 2", status: "pending" },
+        { step: "Step 3", status: "pending" },
+      ],
+    });
+
+    expect(formatArgsDisplay(args, "update_plan").display).toBe("3 items");
+  });
+
+  test("handles singular plan item count for UpdatePlan", () => {
+    const args = JSON.stringify({
+      explanation: "One-step fix",
+      plan: [{ step: "Step 1", status: "pending" }],
+    });
+
+    expect(formatArgsDisplay(args, "UpdatePlan").display).toBe("1 item");
+  });
+
+  test("shows only todo item count for TODO tools", () => {
+    const args = JSON.stringify({
+      todos: [
+        { content: "First", status: "pending" },
+        { content: "Second", status: "in_progress" },
+      ],
+      note: "extra metadata",
+    });
+
+    expect(formatArgsDisplay(args, "TodoWrite").display).toBe("2 items");
+    expect(formatArgsDisplay(args, "write_todos").display).toBe("2 items");
+  });
+});