chore: import upstream snapshot with attribution

tests/unit/executor-agy.test.ts

@@ -0,0 +1,77 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { getExecutor, AntigravityExecutor } from "../../open-sse/executors/index.ts";
+import { processAntigravitySSEPayload } from "../../open-sse/executors/antigravity.ts";
+
+function emptyCollected(): any {
+  return {
+    textContent: "",
+    finishReason: "",
+    toolCalls: [],
+    usage: null,
+    remainingCredits: null,
+  };
+}
+
+test("getExecutor('agy') returns AntigravityExecutor (not DefaultExecutor)", () => {
+  const executor = getExecutor("agy");
+  assert.ok(executor instanceof AntigravityExecutor, "agy provider should use AntigravityExecutor");
+});
+
+test("getExecutor('antigravity') returns AntigravityExecutor", () => {
+  const executor = getExecutor("antigravity");
+  assert.ok(
+    executor instanceof AntigravityExecutor,
+    "antigravity provider should use AntigravityExecutor"
+  );
+});
+
+test("getExecutor('agy') builds valid streaming URL", () => {
+  const executor = getExecutor("agy");
+  const url = executor.buildUrl("gemini-3.5-flash-high", true);
+  assert.ok(
+    url.includes("streamGenerateContent?alt=sse"),
+    `expected streaming endpoint URL, got: ${url}`
+  );
+});
+
+test("getExecutor('agy') builds valid non-streaming URL", () => {
+  const executor = getExecutor("agy");
+  const url = executor.buildUrl("gemini-3.5-flash-high", false);
+  // Antigravity executor always uses streaming endpoint (buildUrl ignores stream flag)
+  assert.ok(
+    url.includes("streamGenerateContent?alt=sse"),
+    `expected streaming endpoint URL (always), got: ${url}`
+  );
+});
+
+test("getExecutor('agy') buildHeaders returns Bearer auth", () => {
+  const executor = getExecutor("agy");
+  const headers = executor.buildHeaders({ accessToken: "test-token" });
+  assert.equal(headers.Authorization, "Bearer test-token");
+});
+
+// #3821-review LEDGER-9 — the Antigravity SSE `markdown` extraction branch had no test.
+test("processAntigravitySSEPayload accumulates top-level markdown into textContent", () => {
+  const collected = emptyCollected();
+  processAntigravitySSEPayload(JSON.stringify({ markdown: "Hello " }), collected);
+  processAntigravitySSEPayload(JSON.stringify({ response: { markdown: "world" } }), collected);
+  assert.equal(collected.textContent, "Hello world");
+});
+
+test("processAntigravitySSEPayload uses candidate parts text when no markdown is present", () => {
+  const collected = emptyCollected();
+  processAntigravitySSEPayload(
+    JSON.stringify({ response: { candidates: [{ content: { parts: [{ text: "from parts" }] } }] } }),
+    collected
+  );
+  assert.equal(collected.textContent, "from parts");
+});
+
+test("processAntigravitySSEPayload ignores [DONE] and malformed payloads without throwing", () => {
+  const collected = emptyCollected();
+  processAntigravitySSEPayload("[DONE]", collected);
+  processAntigravitySSEPayload("{not json", collected);
+  assert.equal(collected.textContent, "");
+});