fix(engine): warn on out-of-range self-plagiarism similarityThreshold

packages/loopover-engine/src/miner-goal-spec.ts

@@ -255,18 +255,22 @@ function normalizeSelfPlagiarismPolicy(
     warnings.push(`MinerGoalSpec field "${field}" must be a mapping; falling back to defaults.`);
     return fallback;
   }
-  const resolved = resolveSelfPlagiarismConfig(value);
   const record = value as Record<string, unknown>;
-  if (
-    record.similarityThreshold !== undefined &&
-    typeof record.similarityThreshold !== "number"
-  ) {
-    warnings.push(
-      `MinerGoalSpec field "${field}.similarityThreshold" must be a number; falling back to ${fallback.similarityThreshold}.`,
-    );
-    return fallback;
+  if (record.similarityThreshold !== undefined) {
+    if (typeof record.similarityThreshold !== "number" || !Number.isFinite(record.similarityThreshold)) {
+      warnings.push(
+        `MinerGoalSpec field "${field}.similarityThreshold" must be a number; falling back to ${fallback.similarityThreshold}.`,
+      );
+      return fallback;
+    }
+    if (record.similarityThreshold < 0 || record.similarityThreshold > 1) {
+      warnings.push(
+        `MinerGoalSpec field "${field}.similarityThreshold" must be between 0 and 1; falling back to ${fallback.similarityThreshold}.`,
+      );
+      return fallback;
+    }
   }
-  return resolved;
+  return resolveSelfPlagiarismConfig(value);
 }
 
 function normalizeKillSwitchPolicy(

packages/loopover-engine/test/miner-goal-spec-parser.test.ts

@@ -215,6 +215,36 @@ test("parseMinerGoalSpec: malformed fields fall back independently with targeted
   assert.match(warningText, /truncated an over-long entry/i);
 });
 
+test("parseMinerGoalSpec: selfPlagiarism.similarityThreshold out of [0,1] warns and falls back (#8862)", () => {
+  const tooHigh = parseMinerGoalSpec({
+    wantedPaths: ["src/**"],
+    selfPlagiarism: { similarityThreshold: 5 },
+  });
+  assert.deepEqual(tooHigh.spec.selfPlagiarism, { similarityThreshold: 0.85 });
+  assert.match(tooHigh.warnings.join(" "), /selfPlagiarism\.similarityThreshold.*between 0 and 1/i);
+
+  const tooLow = parseMinerGoalSpec({
+    wantedPaths: ["src/**"],
+    selfPlagiarism: { similarityThreshold: -1 },
+  });
+  assert.deepEqual(tooLow.spec.selfPlagiarism, { similarityThreshold: 0.85 });
+  assert.match(tooLow.warnings.join(" "), /selfPlagiarism\.similarityThreshold.*between 0 and 1/i);
+
+  const nonFinite = parseMinerGoalSpec({
+    wantedPaths: ["src/**"],
+    selfPlagiarism: { similarityThreshold: Number.NaN },
+  });
+  assert.deepEqual(nonFinite.spec.selfPlagiarism, { similarityThreshold: 0.85 });
+  assert.match(nonFinite.warnings.join(" "), /selfPlagiarism\.similarityThreshold.*must be a number/i);
+
+  const valid = parseMinerGoalSpec({
+    wantedPaths: ["src/**"],
+    selfPlagiarism: { similarityThreshold: 0.9 },
+  });
+  assert.deepEqual(valid.spec.selfPlagiarism, { similarityThreshold: 0.9 });
+  assert.deepEqual(valid.warnings, []);
+});
+
 test("parseMinerGoalSpec: unknown-only or default-only content stays absent with a fallback warning", () => {
   const unknownOnly = parseMinerGoalSpec({ mystery: true });
   assert.equal(unknownOnly.present, false);