chore: import upstream snapshot with attribution

tests/unit/compression/riskGateStep.test.ts

@@ -0,0 +1,61 @@
+/**
+ * TDD for risk-gate mask/restore round-trip.
+ * Run: node --import tsx/esm --test tests/unit/compression/riskGateStep.test.ts
+ */
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+import { applyRiskMask, restoreRiskBlocks } from "../../../open-sse/services/compression/riskGate/riskGateStep.ts";
+import {
+  DEFAULT_COMPRESSION_CONFIG,
+  type CompressionConfig,
+} from "../../../open-sse/services/compression/types.ts";
+
+const PEM = "-----BEGIN PRIVATE KEY-----\nMIIBVQbody\n-----END PRIVATE KEY-----";
+
+describe("applyRiskMask / restoreRiskBlocks", () => {
+  it("masks risky spans in message content and round-trips byte-identically", () => {
+    const body = { messages: [{ role: "user", content: `here is a key:\n${PEM}\nthanks` }] };
+    const { maskedBody, blocks, stats } = applyRiskMask(body, { enabled: true });
+    const maskedText = (maskedBody.messages as Array<{ content: string }>)[0].content;
+    assert.ok(!maskedText.includes("BEGIN PRIVATE KEY"), "secret removed from masked body");
+    assert.ok(maskedText.includes("OMNI_CAVEMAN"), "uses SENTINEL placeholder family");
+    assert.equal(stats.spansProtected, 1);
+    assert.equal(stats.categories.private_key, 1);
+
+    const restored = restoreRiskBlocks(maskedBody, blocks);
+    assert.equal((restored.messages as Array<{ content: string }>)[0].content, body.messages[0].content);
+  });
+
+  it("is a no-op when nothing risky is present", () => {
+    const body = { messages: [{ role: "user", content: "just normal prose, nothing to see" }] };
+    const { maskedBody, blocks, stats } = applyRiskMask(body, { enabled: true });
+    assert.equal(blocks.length, 0);
+    assert.equal(stats.spansProtected, 0);
+    assert.deepEqual(maskedBody, body);
+  });
+
+  it("masks text parts inside array (multimodal) content", () => {
+    const body = {
+      messages: [{ role: "user", content: [{ type: "text", text: `key:\n${PEM}` }, { type: "image_url", image_url: { url: "x" } }] }],
+    };
+    const { maskedBody, blocks } = applyRiskMask(body, { enabled: true });
+    const part = (maskedBody.messages as Array<{ content: Array<{ type: string; text?: string }> }>)[0].content[0];
+    assert.ok(!part.text!.includes("BEGIN PRIVATE KEY"));
+    const restored = restoreRiskBlocks(maskedBody, blocks);
+    assert.equal(
+      (restored.messages as Array<{ content: Array<{ text?: string }> }>)[0].content[0].text,
+      `key:\n${PEM}`
+    );
+  });
+});
+
+describe("risk-gate config defaults", () => {
+  it("ships disabled by default", () => {
+    assert.equal(DEFAULT_COMPRESSION_CONFIG.riskGate?.enabled ?? false, false);
+  });
+  it("accepts a riskGate field on CompressionConfig", () => {
+    const cfg: CompressionConfig = { ...DEFAULT_COMPRESSION_CONFIG, riskGate: { enabled: true } };
+    assert.equal(cfg.riskGate?.enabled, true);
+  });
+});