diff --git a/test/git-auto-init.test.js b/test/git-auto-init.test.js
index db651d91..e22b99c4 100644
--- a/test/git-auto-init.test.js
+++ b/test/git-auto-init.test.js
@@ -141,6 +141,14 @@ describe('Git auto-init on first push', () => {
     await fs.ensureDir(DATA_DIR_AUTH);
     const port = await getAvailablePort();
     const authBaseUrl = `http://${TEST_HOST}:${port}`;
+    // createServer({ root }) mutates process.env.DATA_ROOT globally, and
+    // handleGit resolves the data root PER REQUEST via getDataRoot().
+    // Without restoring the env afterwards, every later test in this
+    // file silently runs against DATA_DIR_AUTH instead of DATA_DIR —
+    // auto-initing repos in the wrong tree and leaving the authcheck
+    // directory behind after the suite's cleanup (which only removes
+    // DATA_DIR). Same pollution class as the #543 review finding.
+    const originalDataRoot = process.env.DATA_ROOT;
     const authServer = createServer({
       logger: false,
       root: DATA_DIR_AUTH,
@@ -162,6 +170,8 @@ describe('Git auto-init on first push', () => {
         'auto-init MUST NOT create a directory for an unauthenticated request');
     } finally {
       await authServer.close();
+      if (originalDataRoot === undefined) delete process.env.DATA_ROOT;
+      else process.env.DATA_ROOT = originalDataRoot;
       await fs.remove(DATA_DIR_AUTH);
     }
   });
diff --git a/test/git-handler.test.js b/test/git-handler.test.js
new file mode 100644
index 00000000..4ecbd430
--- /dev/null
+++ b/test/git-handler.test.js
@@ -0,0 +1,238 @@
+/**
+ * Git handler HTTP contract (#375).
+ *
+ * src/handlers/git.js previously had no automated coverage — the #371
+ * (CORS) and #373 (multi-slash) fixes were verified by hand. These
+ * tests pin the HTTP-level contract:
+ *
+ *   - OPTIONS preflight carries the canonical git CORS headers
+ *   - info/refs advertise works through single/double/triple-slash
+ *     URLs (#373 regression — git http-backend rejects "aliased"
+ *     paths, so JSS collapses multi-slash before forwarding)
+ *   - missing repo → 404 WITH CORS headers (#374 regression — without
+ *     them a browser git client sees a CORS error, not the 404)
+ *   - path traversal attempts are blocked (never 200, never 500)
+ *     with CORS headers
+ *   - unauthenticated push advertise → 401 + WWW-Authenticate
+ *     (NOTE: this 401 is emitted by the server.js WAC preHandler,
+ *     which does NOT currently set the git CORS headers — that gap is
+ *     tracked separately; the test asserts what is true today)
+ *   - a real end-to-end `git push` succeeds and the pushed file is
+ *     served as a static resource (receive-pack POST through
+ *     http-backend + updateInstead extraction)
+ *
+ * Boot pattern mirrors test/git-auto-init.test.js: temp data dir,
+ * `git: true, public: true` so WAC is open and the handler logic is
+ * exercised in isolation. The 401 case boots a second, non-public
+ * server and snapshots/restores process.env.DATA_ROOT around it
+ * (createServer({ root }) mutates it globally).
+ */
+
+import { describe, it, before, after } from 'node:test';
+import assert from 'node:assert';
+import { createServer } from '../src/server.js';
+import { createServer as createNetServer } from 'net';
+import { spawn, spawnSync } from 'child_process';
+import fs from 'fs-extra';
+import path from 'path';
+
+const TEST_HOST = 'localhost';
+const DATA_DIR = './test-data-git-handler';
+const LOCAL_REPO = './test-data-git-handler-local';
+
+function getAvailablePort() {
+  return new Promise((resolve, reject) => {
+    const srv = createNetServer();
+    srv.on('error', reject);
+    srv.listen(0, TEST_HOST, () => {
+      const port = srv.address().port;
+      srv.close(() => resolve(port));
+    });
+  });
+}
+
+// Synchronous git for purely-LOCAL operations (init/add/commit). Fine
+// to block the event loop because no in-process server is involved.
+function git(args, cwd) {
+  const res = spawnSync('git', args, { cwd, stdio: ['ignore', 'pipe', 'pipe'] });
+  return {
+    status: res.status,
+    stdout: res.stdout?.toString() || '',
+    stderr: res.stderr?.toString() || '',
+  };
+}
+
+// Async git for operations that talk to the in-process test server
+// (push). spawnSync would block the event loop, the server could never
+// respond, and the test would deadlock until the runner times out.
+//
+// GIT_TERMINAL_PROMPT=0 makes git fail fast instead of waiting on a
+// credential prompt if the remote unexpectedly challenges (stdin is
+// 'ignore', so a prompt could otherwise wedge the test in CI). The
+// `error` listener covers spawn-level failures (e.g. git missing from
+// PATH), where `close` may never fire and the promise would hang.
+function gitAsync(args, cwd) {
+  return new Promise((resolve) => {
+    const child = spawn('git', args, {
+      cwd,
+      stdio: ['ignore', 'pipe', 'pipe'],
+      env: { ...process.env, GIT_TERMINAL_PROMPT: '0' },
+    });
+    let stdout = '';
+    let stderr = '';
+    child.stdout.on('data', (d) => { stdout += d; });
+    child.stderr.on('data', (d) => { stderr += d; });
+    child.on('error', (err) => resolve({ status: -1, stdout, stderr: `spawn failed: ${err.message}` }));
+    child.on('close', (status) => resolve({ status, stdout, stderr }));
+  });
+}
+
+function assertGitCors(res, label) {
+  assert.strictEqual(res.headers.get('access-control-allow-origin'), '*',
+    `${label}: Access-Control-Allow-Origin must be *`);
+  assert.strictEqual(res.headers.get('access-control-allow-methods'), 'GET, POST, OPTIONS',
+    `${label}: Access-Control-Allow-Methods mismatch`);
+  assert.strictEqual(res.headers.get('access-control-allow-headers'), 'Content-Type, Authorization, Git-Protocol',
+    `${label}: Access-Control-Allow-Headers must include Git-Protocol (#371)`);
+}
+
+describe('git handler HTTP contract (#375)', () => {
+  let server;
+  let baseUrl;
+  // Repo created once in before() via a real receive-pack advertise
+  // (auto-init), then reused by the advertise/slash tests below.
+  const REPO = 'public/site';
+
+  before(async () => {
+    await fs.remove(DATA_DIR);
+    await fs.ensureDir(DATA_DIR);
+
+    const port = await getAvailablePort();
+    baseUrl = `http://${TEST_HOST}:${port}`;
+
+    server = createServer({
+      logger: false,
+      root: DATA_DIR,
+      git: true,
+      public: true,
+    });
+    await server.listen({ port, host: TEST_HOST });
+
+    // Materialize a repo at REPO via the auto-init path so the
+    // upload-pack advertise tests have something real to talk to.
+    const res = await fetch(`${baseUrl}/${REPO}/info/refs?service=git-receive-pack`);
+    assert.strictEqual(res.status, 200, 'prereq: auto-init advertise must succeed');
+  });
+
+  after(async () => {
+    if (server) await server.close();
+    await fs.remove(DATA_DIR);
+    await fs.remove(LOCAL_REPO);
+  });
+
+  it('OPTIONS preflight returns 200 with the canonical git CORS headers', async () => {
+    const res = await fetch(`${baseUrl}/${REPO}/info/refs?service=git-upload-pack`, {
+      method: 'OPTIONS',
+    });
+    assert.strictEqual(res.status, 200, 'preflight must be 200');
+    assertGitCors(res, 'OPTIONS preflight');
+  });
+
+  it('single-slash info/refs advertise returns 200 with the advertisement content type', async () => {
+    const res = await fetch(`${baseUrl}/${REPO}/info/refs?service=git-upload-pack`);
+    assert.strictEqual(res.status, 200);
+    assert.strictEqual(res.headers.get('content-type'),
+      'application/x-git-upload-pack-advertisement');
+  });
+
+  it('double-slash //info/refs returns 200 (#373 regression)', async () => {
+    // git http-backend rejects "aliased" multi-slash paths; JSS must
+    // collapse them before forwarding or the request 500s.
+    const res = await fetch(`${baseUrl}/${REPO}//info/refs?service=git-upload-pack`);
+    assert.strictEqual(res.status, 200,
+      `double slash must not break the advertise; got ${res.status}`);
+  });
+
+  it('triple-slash ///info/refs returns 200 (#373 regression)', async () => {
+    const res = await fetch(`${baseUrl}/${REPO}///info/refs?service=git-upload-pack`);
+    assert.strictEqual(res.status, 200,
+      `triple slash must not break the advertise; got ${res.status}`);
+  });
+
+  it('missing repo returns 404 with CORS headers (#374 regression)', async () => {
+    // upload-pack (fetch) on a non-existent path: no auto-init, plain 404.
+    const res = await fetch(`${baseUrl}/public/no-such-repo/info/refs?service=git-upload-pack`);
+    assert.strictEqual(res.status, 404);
+    assertGitCors(res, 'missing-repo 404');
+  });
+
+  it('path traversal attempt is blocked, never 200/500, with CORS headers', async () => {
+    // Percent-encoded so fetch() doesn't normalize the dots away
+    // client-side. handleGit decodes, strips `..`, and containment-
+    // checks the result — depending on what survives sanitization the
+    // response is 403 (escape detected) or 404 (sanitized path has no
+    // repo). Both are acceptable; 200 (leak) and 500 (crash) are not.
+    const res = await fetch(
+      `${baseUrl}/%2e%2e/%2e%2e/%2e%2e/etc/info/refs?service=git-upload-pack`);
+    assert.ok(res.status === 403 || res.status === 404,
+      `traversal must be blocked with 403/404, got ${res.status}`);
+    assertGitCors(res, 'traversal block');
+  });
+
+  it('unauthenticated push advertise returns 401 with WWW-Authenticate (non-public server)', async () => {
+    // Second server WITHOUT public:true so the WAC preHandler gates
+    // the push. Snapshot/restore DATA_ROOT — createServer({ root })
+    // mutates it process-wide and the main suite's server reads it
+    // per-request.
+    const DATA_DIR_AUTH = './test-data-git-handler-auth';
+    await fs.remove(DATA_DIR_AUTH);
+    await fs.ensureDir(DATA_DIR_AUTH);
+    const port = await getAvailablePort();
+    const originalDataRoot = process.env.DATA_ROOT;
+    const authServer = createServer({ logger: false, root: DATA_DIR_AUTH, git: true });
+    try {
+      await authServer.listen({ port, host: TEST_HOST });
+      const res = await fetch(
+        `http://${TEST_HOST}:${port}/public/x/info/refs?service=git-receive-pack`);
+      assert.strictEqual(res.status, 401,
+        `unauthenticated push advertise must be 401, got ${res.status}`);
+      assert.ok(res.headers.get('www-authenticate'),
+        'WWW-Authenticate must be present so git CLI clients prompt for credentials');
+      // Deliberately NOT asserting CORS here: the WAC preHandler's
+      // 401 path does not currently set the git CORS headers (tracked
+      // as a follow-up). Assert truth, not aspiration.
+    } finally {
+      await authServer.close();
+      if (originalDataRoot === undefined) delete process.env.DATA_ROOT;
+      else process.env.DATA_ROOT = originalDataRoot;
+      await fs.remove(DATA_DIR_AUTH);
+    }
+  });
+
+  it('end-to-end push succeeds and the pushed file is served as a static resource', async () => {
+    // Build a local repo with one file and push it. Auto-init pins the
+    // server-side HEAD to refs/heads/main (#471), so pushing HEAD:main
+    // triggers receive.denyCurrentBranch=updateInstead extraction and
+    // the file becomes a static resource at the pod URL.
+    await fs.remove(LOCAL_REPO);
+    await fs.ensureDir(LOCAL_REPO);
+    assert.strictEqual(git(['init', '--quiet'], LOCAL_REPO).status, 0, 'git init');
+    await fs.writeFile(path.join(LOCAL_REPO, 'index.html'), '<p>pushed-via-test</p>\n');
+    assert.strictEqual(git(['add', 'index.html'], LOCAL_REPO).status, 0, 'git add');
+    const commit = git([
+      '-c', 'user.email=test@example.invalid',
+      '-c', 'user.name=jss-test',
+      'commit', '--quiet', '-m', 'test commit',
+    ], LOCAL_REPO);
+    assert.strictEqual(commit.status, 0, `git commit failed: ${commit.stderr}`);
+
+    const push = await gitAsync(['push', '--quiet', `${baseUrl}/public/pushed-site`, 'HEAD:main'], LOCAL_REPO);
+    assert.strictEqual(push.status, 0, `git push failed: ${push.stderr.slice(0, 400)}`);
+
+    // updateInstead extracted the working tree → file is now served.
+    const res = await fetch(`${baseUrl}/public/pushed-site/index.html`);
+    assert.strictEqual(res.status, 200, 'pushed file must be served over HTTP');
+    const body = await res.text();
+    assert.ok(body.includes('pushed-via-test'), 'served content must match the pushed file');
+  });
+});