test: add auth gating unit tests

Tests for GITHUB_TOKEN, GH_TOKEN fallback, and missing-token error shape.
Also fixes pre-push hook failure when no test files existed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: AlbinoGeek

src/server/github-auth.test.ts

@@ -0,0 +1,72 @@
+import { describe, expect, test } from "bun:test";
+
+import { gateAuth, resetAuthCache } from "./github-auth.js";
+
+describe("gateAuth", () => {
+  test("returns github_auth_missing when no token is available", () => {
+    const origGH = process.env.GITHUB_TOKEN;
+    const origGHT = process.env.GH_TOKEN;
+    delete process.env.GITHUB_TOKEN;
+    delete process.env.GH_TOKEN;
+    resetAuthCache();
+
+    const result = gateAuth();
+    // If gh CLI is installed and authed, this will succeed — that's fine.
+    // We only assert the shape is correct either way.
+    expect(result).toHaveProperty("ok");
+    if (!result.ok) {
+      expect(result.body).toHaveProperty("error", "github_auth_missing");
+    }
+
+    // Restore
+    if (origGH !== undefined) process.env.GITHUB_TOKEN = origGH;
+    if (origGHT !== undefined) process.env.GH_TOKEN = origGHT;
+    resetAuthCache();
+  });
+
+  test("returns ok when GITHUB_TOKEN is set", () => {
+    const origGH = process.env.GITHUB_TOKEN;
+    const origGHT = process.env.GH_TOKEN;
+    process.env.GITHUB_TOKEN = "test-token-123";
+    delete process.env.GH_TOKEN;
+    resetAuthCache();
+
+    const result = gateAuth();
+    expect(result.ok).toBe(true);
+    if (result.ok) {
+      expect(result.token).toBe("test-token-123");
+    }
+
+    // Restore
+    if (origGH !== undefined) {
+      process.env.GITHUB_TOKEN = origGH;
+    } else {
+      delete process.env.GITHUB_TOKEN;
+    }
+    if (origGHT !== undefined) process.env.GH_TOKEN = origGHT;
+    resetAuthCache();
+  });
+
+  test("falls back to GH_TOKEN", () => {
+    const origGH = process.env.GITHUB_TOKEN;
+    const origGHT = process.env.GH_TOKEN;
+    delete process.env.GITHUB_TOKEN;
+    process.env.GH_TOKEN = "gh-token-456";
+    resetAuthCache();
+
+    const result = gateAuth();
+    expect(result.ok).toBe(true);
+    if (result.ok) {
+      expect(result.token).toBe("gh-token-456");
+    }
+
+    // Restore
+    if (origGH !== undefined) process.env.GITHUB_TOKEN = origGH;
+    if (origGHT !== undefined) {
+      process.env.GH_TOKEN = origGHT;
+    } else {
+      delete process.env.GH_TOKEN;
+    }
+    resetAuthCache();
+  });
+});