feat(claude): merge client anthropic-beta flags and forward rate-limit headers

tests/unit/anthropic-gateway-passthrough.test.js

@@ -0,0 +1,80 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { mergeAnthropicBeta } from "open-sse/providers/shared.js";
+import { upstreamResponseHeaders } from "open-sse/utils/upstreamHeaders.js";
+import { createErrorResult, unavailableResponse } from "open-sse/utils/error.js";
+
+const betaFlags = (headers) => (headers["Anthropic-Beta"] || "").split(",").map((s) => s.trim()).filter(Boolean);
+
+describe("mergeAnthropicBeta", () => {
+  it("unions and dedupes comma lists, ignoring blanks", () => {
+    expect(mergeAnthropicBeta("a,b", " b , c ,", undefined, "")).toBe("a,b,c");
+  });
+});
+
+describe("DefaultExecutor.buildHeaders() forwards client anthropic-beta", () => {
+  let DefaultExecutor;
+
+  beforeEach(async () => {
+    vi.resetModules();
+    ({ DefaultExecutor } = await import("open-sse/executors/default.js"));
+  });
+
+  it("keeps unknown client flags alongside the pinned set on claude", () => {
+    const executor = new DefaultExecutor("claude");
+    const rawHeaders = { "anthropic-beta": "safeguards-2026-09-01,context-1m-2025-08-07" };
+    const flags = betaFlags(executor.buildHeaders({ apiKey: "k", rawHeaders }, true, undefined, "claude-opus-5"));
+    expect(flags).toContain("safeguards-2026-09-01");
+    expect(flags).toContain("context-1m-2025-08-07");
+    expect(flags).toContain("context-management-2025-06-27");
+    expect(new Set(flags).size).toBe(flags.length);
+  });
+
+  it("forwards client flags on anthropic-compatible Claude models", () => {
+    const executor = new DefaultExecutor("anthropic-compatible-custom");
+    const creds = { apiKey: "k", rawHeaders: { "anthropic-beta": "safeguards-2026-09-01" }, providerSpecificData: { baseUrl: "https://gw.example.com/v1" } };
+    const flags = betaFlags(executor.buildHeaders(creds, true, undefined, "claude-sonnet-5"));
+    expect(flags).toContain("safeguards-2026-09-01");
+    expect(flags).not.toContain("claude-code-20250219");
+  });
+
+  it("forwards client flags on the anthropic provider", () => {
+    const executor = new DefaultExecutor("anthropic");
+    const flags = betaFlags(executor.buildHeaders({ apiKey: "k", rawHeaders: { "anthropic-beta": "safeguards-2026-09-01" } }, true, undefined, "claude-sonnet-5"));
+    expect(flags).toContain("safeguards-2026-09-01");
+  });
+});
+
+describe("upstream response header forwarding", () => {
+  const upstream = new Headers({
+    "retry-after": "12",
+    "x-should-retry": "false",
+    "anthropic-ratelimit-unified-status": "rejected",
+    "anthropic-ratelimit-unified-reset": "1790000000",
+    "set-cookie": "secret=1",
+    "content-length": "99",
+  });
+
+  it("picks only retry and ratelimit headers", () => {
+    expect(upstreamResponseHeaders(upstream)).toEqual({
+      "retry-after": "12",
+      "x-should-retry": "false",
+      "anthropic-ratelimit-unified-status": "rejected",
+      "anthropic-ratelimit-unified-reset": "1790000000",
+    });
+    expect(upstreamResponseHeaders(undefined)).toEqual({});
+  });
+
+  it("attaches them to error results", () => {
+    const { response } = createErrorResult(429, "limited", undefined, upstreamResponseHeaders(upstream));
+    expect(response.headers.get("x-should-retry")).toBe("false");
+    expect(response.headers.get("anthropic-ratelimit-unified-status")).toBe("rejected");
+    expect(response.headers.get("set-cookie")).toBeNull();
+  });
+
+  it("keeps the gateway retry-after on all-accounts-limited responses", () => {
+    const retryAt = new Date(Date.now() + 30000).toISOString();
+    const res = unavailableResponse(503, "busy", retryAt, "30s", upstreamResponseHeaders(upstream));
+    expect(Number(res.headers.get("retry-after"))).toBeGreaterThan(20);
+    expect(res.headers.get("anthropic-ratelimit-unified-reset")).toBe("1790000000");
+  });
+});