chore: import upstream snapshot with attribution

tests/unit/compression/sessionDedupFuzzy.test.ts

@@ -0,0 +1,54 @@
+// tests/unit/compression/sessionDedupFuzzy.test.ts
+import test from "node:test";
+import assert from "node:assert/strict";
+import { sessionDedupEngine } from "../../../open-sse/services/compression/engines/session-dedup/index.ts";
+import { retrieveBlock, resetCcrStore } from "../../../open-sse/services/compression/engines/ccr/index.ts";
+
+const A = "alpha beta gamma delta epsilon zeta eta theta iota kappa lambda mu nu xi omicron pi rho";
+const Aprime = A + " sigma"; // ≥0.85 similar, not identical
+
+test("fuzzy enabled: a near-duplicate message becomes a recoverable CCR marker", () => {
+  resetCcrStore();
+  const body = { messages: [{ role: "user", content: A }, { role: "user", content: Aprime }] };
+  const res = sessionDedupEngine.apply(body, { stepConfig: { fuzzy: { enabled: true } }, principalId: "p1" });
+  assert.equal(res.compressed, true);
+  const msgs = (res.body.messages as Array<{ content: string }>);
+  assert.equal(msgs[0].content, A); // first occurrence intact
+  assert.match(msgs[1].content, /^\[CCR retrieve hash=[0-9a-f]{24} chars=\d+\]$/);
+  const hash = msgs[1].content.match(/hash=([0-9a-f]{24})/)![1];
+  assert.equal(retrieveBlock(hash, "p1"), Aprime); // recoverable
+});
+
+test("fuzzy ABSENT: byte-identical legacy (near-dup untouched, only exact dedup runs)", () => {
+  resetCcrStore();
+  const body = { messages: [{ role: "user", content: A }, { role: "user", content: Aprime }] };
+  const res = sessionDedupEngine.apply(body, { stepConfig: {}, principalId: "p1" });
+  // no exact-identical blocks here → no-op
+  assert.equal(res.compressed, false);
+});
+
+test("fuzzy enabled but below threshold → untouched", () => {
+  resetCcrStore();
+  const body = { messages: [
+    { role: "user", content: A },
+    { role: "user", content: "completely unrelated content with no shared three word windows whatsoever here ok" },
+  ] };
+  const res = sessionDedupEngine.apply(body, { stepConfig: { fuzzy: { enabled: true, minJaccard: 0.85 } }, principalId: "p1" });
+  assert.equal(res.compressed, false);
+});
+
+test("config schema advertises the fuzzy toggle + validateConfig accepts a fuzzy block", () => {
+  const schema = sessionDedupEngine.getConfigSchema();
+  assert.ok(schema.some((f) => f.key === "fuzzy"));
+  assert.equal(sessionDedupEngine.validateConfig({ fuzzy: { enabled: true } }).valid, true);
+  assert.equal(sessionDedupEngine.validateConfig({ fuzzy: { enabled: "yes" } }).valid, false);
+});
+
+test("fuzzy as a bare boolean true also fires (schema advertises type:boolean)", () => {
+  resetCcrStore();
+  const body = { messages: [{ role: "user", content: A }, { role: "user", content: Aprime }] };
+  const res = sessionDedupEngine.apply(body, { stepConfig: { fuzzy: true }, principalId: "p1" });
+  assert.equal(res.compressed, true);
+  const msgs = res.body.messages as Array<{ content: string }>;
+  assert.match(msgs[1].content, /^\[CCR retrieve hash=[0-9a-f]{24} chars=\d+\]$/);
+});