fix: report EnterPlanMode tool calls with the switch_mode kind (#1467)

Stacked on #1457 (SDK 2.1.0).

EnterPlanMode tool calls now use `kind: "switch_mode"`, like
ExitPlanMode (agentclientprotocol/agent-client-protocol#2543). The title
is unchanged.

src/tests/tools.test.ts

@@ -2448,6 +2448,18 @@ describe("toolInfoFromToolUse - ExitPlanMode", () => {
   });
 });
 
+describe("toolInfoFromToolUse - EnterPlanMode", () => {
+  it("reports a mode switch", () => {
+    const info = toolInfoFromToolUse(
+      { name: "EnterPlanMode", id: "toolu_enter", input: {} },
+      false,
+    );
+
+    expect(info.kind).toBe("switch_mode");
+    expect(info.title).toBe("EnterPlanMode");
+  });
+});
+
 describe("toolInfoFromToolUse - Write input aliases", () => {
   it.each([
     ["path + file_text", { path: "/repo/a.ts", file_text: "x" }],

src/tool-calls/reporters/index.ts

@@ -5,6 +5,7 @@ import { EditReporter, NotebookEditReporter, WriteReporter } from "./file-edit.j
 import {
   AgentControlReporter,
   AskUserQuestionReporter,
+  EnterPlanModeReporter,
   ExitPlanModeReporter,
   GenericReporter,
   PlanToolReporter,
@@ -35,6 +36,7 @@ const reporters: Record<string, ToolReporter> = {
   TaskList: new PlanToolReporter("TaskList"),
   TaskGet: new PlanToolReporter("TaskGet"),
   ReportFindings: new ReportFindingsReporter(),
+  EnterPlanMode: new EnterPlanModeReporter(),
   ExitPlanMode: new ExitPlanModeReporter(),
   AskUserQuestion: new AskUserQuestionReporter(),
   Skill: new SkillReporter(),

src/tool-calls/reporters/interaction.ts

@@ -72,6 +72,13 @@ export class ExitPlanModeReporter implements ToolReporter {
   }
 }
 
+/** EnterPlanMode switches the session to plan mode, so it has the `switch_mode` kind like ExitPlanMode. */
+export class EnterPlanModeReporter implements ToolReporter {
+  toolUse(): ToolUseFacts {
+    return { title: "EnterPlanMode", kind: "switch_mode" };
+  }
+}
+
 /** The plan file of a result: the path of the input, else the `filePath` of the structured result. */
 function resultPlanFile({ toolUse, structured, capabilities }: ToolResultContext) {
   if (!capabilities.air.planFile) return undefined;