fix(ai): ignore generic GitHub tokens for Copilot auth

closes #4485

packages/ai/test/env-api-keys.test.ts

@@ -0,0 +1,46 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { findEnvKeys, getEnvApiKey } from "../src/env-api-keys.js";
+
+const originalCopilotGitHubToken = process.env.COPILOT_GITHUB_TOKEN;
+const originalGhToken = process.env.GH_TOKEN;
+const originalGitHubToken = process.env.GITHUB_TOKEN;
+
+afterEach(() => {
+	if (originalCopilotGitHubToken === undefined) {
+		delete process.env.COPILOT_GITHUB_TOKEN;
+	} else {
+		process.env.COPILOT_GITHUB_TOKEN = originalCopilotGitHubToken;
+	}
+
+	if (originalGhToken === undefined) {
+		delete process.env.GH_TOKEN;
+	} else {
+		process.env.GH_TOKEN = originalGhToken;
+	}
+
+	if (originalGitHubToken === undefined) {
+		delete process.env.GITHUB_TOKEN;
+	} else {
+		process.env.GITHUB_TOKEN = originalGitHubToken;
+	}
+});
+
+describe("environment API keys", () => {
+	it("does not treat generic GitHub tokens as GitHub Copilot credentials", () => {
+		delete process.env.COPILOT_GITHUB_TOKEN;
+		process.env.GH_TOKEN = "gh-token";
+		process.env.GITHUB_TOKEN = "github-token";
+
+		expect(findEnvKeys("github-copilot")).toBeUndefined();
+		expect(getEnvApiKey("github-copilot")).toBeUndefined();
+	});
+
+	it("resolves GitHub Copilot credentials from COPILOT_GITHUB_TOKEN", () => {
+		process.env.COPILOT_GITHUB_TOKEN = "copilot-token";
+		process.env.GH_TOKEN = "gh-token";
+		process.env.GITHUB_TOKEN = "github-token";
+
+		expect(findEnvKeys("github-copilot")).toEqual(["COPILOT_GITHUB_TOKEN"]);
+		expect(getEnvApiKey("github-copilot")).toBe("copilot-token");
+	});
+});