feat(auth): add csrfOriginCheck middleware

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/web/middleware/csrf.test.ts

@@ -0,0 +1,58 @@
+import { describe, it, expect, beforeEach } from "vitest";
+import express from "express";
+import request from "supertest";
+import { csrfOriginCheck } from "./csrf.js";
+
+describe("csrfOriginCheck middleware", () => {
+  let app: express.Express;
+
+  beforeEach(() => {
+    app = express();
+    app.use(csrfOriginCheck);
+    app.get("/", (_req, res) => res.json({ ok: true }));
+    app.post("/", (_req, res) => res.json({ ok: true }));
+  });
+
+  it("allows safe methods (GET/HEAD/OPTIONS) without Origin", async () => {
+    const res = await request(app).get("/");
+    expect(res.status).toBe(200);
+  });
+
+  it("rejects POST without Origin or Referer", async () => {
+    const res = await request(app).post("/");
+    expect(res.status).toBe(403);
+    expect(res.body).toEqual({ error: "bad origin" });
+  });
+
+  it("accepts POST when Origin host matches request host", async () => {
+    const res = await request(app)
+      .post("/")
+      .set("Host", "example.com")
+      .set("Origin", "https://example.com");
+    expect(res.status).toBe(200);
+  });
+
+  it("rejects POST when Origin host does not match request host", async () => {
+    const res = await request(app)
+      .post("/")
+      .set("Host", "example.com")
+      .set("Origin", "https://evil.com");
+    expect(res.status).toBe(403);
+  });
+
+  it("accepts POST when Referer host matches and Origin is absent", async () => {
+    const res = await request(app)
+      .post("/")
+      .set("Host", "example.com")
+      .set("Referer", "https://example.com/some/path");
+    expect(res.status).toBe(200);
+  });
+
+  it("rejects POST when Referer host does not match", async () => {
+    const res = await request(app)
+      .post("/")
+      .set("Host", "example.com")
+      .set("Referer", "https://evil.com/some/path");
+    expect(res.status).toBe(403);
+  });
+});