fix(claude-code): use native Windows claude lookup

src/resources/extensions/claude-code-cli/stream-adapter.ts

@@ -50,6 +50,17 @@ function createAssistantStream(): AssistantMessageEventStream {
 
 let cachedClaudePath: string | null = null;
 
+export function getClaudeLookupCommand(platform: NodeJS.Platform = process.platform): string {
+	return platform === "win32" ? "where claude" : "which claude";
+}
+
+export function parseClaudeLookupOutput(output: Buffer | string): string {
+	return output
+		.toString()
+		.trim()
+		.split(/\r?\n/)[0] ?? "";
+}
+
 /**
  * Resolve the path to the system-installed `claude` binary.
  * The SDK defaults to a bundled cli.js which doesn't exist when
@@ -58,9 +69,7 @@ let cachedClaudePath: string | null = null;
 function getClaudePath(): string {
 	if (cachedClaudePath) return cachedClaudePath;
 	try {
-		cachedClaudePath = execSync("which claude", { timeout: 5_000, stdio: "pipe" })
-			.toString()
-			.trim();
+		cachedClaudePath = parseClaudeLookupOutput(execSync(getClaudeLookupCommand(), { timeout: 5_000, stdio: "pipe" }));
 	} catch {
 		cachedClaudePath = "claude"; // fall back to PATH resolution
 	}

src/resources/extensions/claude-code-cli/tests/stream-adapter.test.ts

@@ -4,6 +4,8 @@ import {
 	makeStreamExhaustedErrorMessage,
 	buildPromptFromContext,
 	buildSdkOptions,
+	getClaudeLookupCommand,
+	parseClaudeLookupOutput,
 } from "../stream-adapter.ts";
 import type { Context, Message } from "@gsd/pi-ai";
 
@@ -126,3 +128,19 @@ describe("stream-adapter — session persistence (#2859)", () => {
 		);
 	});
 });
+
+describe("stream-adapter — Windows Claude path lookup (#3770)", () => {
+	test("getClaudeLookupCommand uses where on Windows", () => {
+		assert.equal(getClaudeLookupCommand("win32"), "where claude");
+	});
+
+	test("getClaudeLookupCommand uses which on non-Windows platforms", () => {
+		assert.equal(getClaudeLookupCommand("darwin"), "which claude");
+		assert.equal(getClaudeLookupCommand("linux"), "which claude");
+	});
+
+	test("parseClaudeLookupOutput keeps the first native path from multi-line lookup output", () => {
+		const output = "C:\\Users\\Binoy\\.local\\bin\\claude.exe\r\nC:\\Program Files\\Claude\\claude.exe\r\n";
+		assert.equal(parseClaudeLookupOutput(output), "C:\\Users\\Binoy\\.local\\bin\\claude.exe");
+	});
+});