feat: /v1/assets/* CORS release proxy

src/rest.ts

@@ -137,6 +137,31 @@ rest.post("/v1/detect", async (c) => {
   return c.json({ count: results.length, results })
 })
 
+const RELEASE_BASE = "https://github.com/interscript/interscript-ml/releases/download"
+
+/**
+ * CORS-enabled streaming proxy for release assets (TODO.client-work 13):
+ * browsers cannot fetch GH Releases directly — the github.com redirect
+ * hop carries no Access-Control-Allow-Origin. Releases stay the origin
+ * of truth; this is the edge front door on the API's own domain.
+ */
+rest.get("/v1/assets/*", async (c) => {
+  const path = c.req.path.replace(/^\/v1\/assets\//, "")
+  if (!/^[A-Za-z0-9][A-Za-z0-9._-]*\/[A-Za-z0-9][A-Za-z0-9._.-]*$/.test(path)) {
+    return errorResponse(400, "bad_request", "path must be {tag}/{file}")
+  }
+  const upstream = await fetch(`${RELEASE_BASE}/${path}`).catch(() => null)
+  if (!upstream || !upstream.ok) {
+    return errorResponse(404, "asset_not_found", `Couldn't locate ${path}`)
+  }
+  const headers = new Headers()
+  headers.set("access-control-allow-origin", "*")
+  headers.set("content-type", upstream.headers.get("content-type") ?? "application/octet-stream")
+  const length = upstream.headers.get("content-length")
+  if (length) headers.set("content-length", length)
+  return new Response(upstream.body, { status: upstream.status, headers })
+})
+
 rest.get("/v1/models", (c) => c.json({ count: listModels().length, models: listModels() }))
 
 rest.get("/v1/models/:id", (c) => {

test/rest.test.ts

@@ -222,3 +222,31 @@ describe("POST /v1/infer/batch", () => {
     expect(many.status).toBe(400)
   })
 })
+
+describe("GET /v1/assets/* (CORS release proxy)", () => {
+  it("streams release assets with permissive CORS and passthrough status", async () => {
+    const originalFetch = globalThis.fetch
+    globalThis.fetch = (async (url: string | URL | Request) => {
+      if (String(url).includes("releases/download")) {
+        return new Response("asset-bytes", {
+          status: 200,
+          headers: { "content-type": "application/octet-stream" },
+        })
+      }
+      return originalFetch(url as RequestInfo)
+    }) as typeof fetch
+    try {
+      const res = await get("/v1/assets/index-v2/models-index.yaml")
+      expect(res.status).toBe(200)
+      expect(res.headers.get("access-control-allow-origin")).toBe("*")
+      expect(await res.text()).toBe("asset-bytes")
+    } finally {
+      globalThis.fetch = originalFetch
+    }
+  })
+
+  it("rejects encoded traversal within the assets path", async () => {
+    const res = await get("/v1/assets/index-v2/..%2fsecret.yaml")
+    expect([400, 404]).toContain(res.status)
+  })
+})