todo_write: rename the items param to todos

A top-level arguments key named "items" shadows minijinja's .items() in Together's GLM-5.2 chat template — every replayed turn 400s.
Old key still executes; GUI renders both; regression tests added.

surfaces/gui/src/App.tsx

@@ -554,7 +554,8 @@ export function App() {
           setStreaming(""); // finalized into items (or empty tool-only turn)
           break;
         case "tool_proposed":
-          if (d.name === "todo_write" && d.arguments?.items) setTodo(normalizeTodos(d.arguments.items));
+          if (d.name === "todo_write" && (d.arguments?.todos || d.arguments?.items))
+            setTodo(normalizeTodos(d.arguments.todos ?? d.arguments.items));
           setItems((p) => [
             ...p,
             { kind: "tool", id: newId(), name: d.name, args: d.arguments, status: "…" },

surfaces/gui/src/components/Transcript.test.tsx

@@ -195,9 +195,14 @@ describe("humanizeTool", () => {
   });
 
   it("summarizes todo_write by its single item and status", () => {
-    const line = humanizeTool("todo_write", { items: [{ content: "Post the digest", status: "in_progress" }] });
+    const line = humanizeTool("todo_write", { todos: [{ content: "Post the digest", status: "in_progress" }] });
     expect(line.pre).toBe("Updated the plan — ");
     expect(line.obj).toContain("Post the digest");
     expect(line.post).toBe(" → in progress");
   });
+
+  it("still renders pre-rename todo_write histories (legacy `items` key)", () => {
+    const line = humanizeTool("todo_write", { items: [{ content: "Old plan", status: "pending" }] });
+    expect(line.obj).toContain("Old plan");
+  });
 });

surfaces/gui/src/humanize.ts

@@ -56,7 +56,9 @@ export function humanizeTool(name: string, args: any): HumanLine {
     case "git_log":
       return { pre: "Looked through recent git history" };
     case "todo_write": {
-      const items = Array.isArray(a.items) ? a.items : [];
+      // `todos` is current; `items` renders histories from before the rename (the old
+      // key breaks Together's GLM-5.2 chat template — see coworker/tools/todo.py).
+      const items = Array.isArray(a.todos) ? a.todos : Array.isArray(a.items) ? a.items : [];
       if (items.length === 1) {
         const it = items[0] || {};
         const status = String(it.status || "").replace(/_/g, " ");