fix(salary): reject non-finite converter baselines (#665)

* fix(salary): reject non-finite converter baselines

* changelog: place the #665 entry under [Unreleased]

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: GAPIT-KIENTH\kienth <kienth@gapit.com.vn>
Co-authored-by: Mads Lorentzen <madslorentzen_17@hotmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -108,6 +108,13 @@ per-file diff commands.
   in `salary_data.json` and `--list-all`. A fallback-detected header with no salary column beside it
   now skips the sheet with a warning; strictly detected headers are unchanged.
 
+- **`convert_salary_excel.py` rejects a non-finite `--baseline`** (#665,
+  `tools/convert_salary_excel.py`, `tests/test_salary_baseline_cli.py`) - `nan`, `inf`, `-inf` and
+  an overflow such as `1e309` were accepted with exit 0 and written as `index_baseline`,
+  overwriting a good `salary_data.json` with one that `salary_lookup.py --validate` rejects; every
+  lookup then failed and `/apply` quietly dropped the benchmark. The converter now exits 2 before
+  reading the workbook or opening the output, and `0` or a finite custom baseline still converts.
+
 ## [1.7.3] - 2026-10-19
 
 ### Added

tests/test_salary_baseline_cli.py

@@ -0,0 +1,57 @@
+"""The converter must not write baselines rejected by salary_lookup --validate."""
+import json
+import subprocess
+import sys
+import unittest
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+try:
+    import openpyxl
+except ImportError:
+    openpyxl = None
+
+TOOL = Path(__file__).resolve().parents[1] / "tools" / "convert_salary_excel.py"
+
+
+@unittest.skipUnless(openpyxl, "requires optional openpyxl (installed in CI)")
+class BaselineCLI(unittest.TestCase):
+    def setUp(self):
+        directory = TemporaryDirectory()
+        self.addCleanup(directory.cleanup)
+        self.root = Path(directory.name)
+        self.workbook = self.root / "salary.xlsx"
+        self.output = self.root / "salary.json"
+        book = openpyxl.Workbook()
+        try:
+            book.active.append(["Company", "Count", "Index"])
+            book.active.append(["Acme", 12, 108.5])
+            book.save(self.workbook)
+        finally:
+            book.close()
+
+    def convert(self, baseline):
+        return subprocess.run(
+            [sys.executable, str(TOOL), str(self.workbook),
+             "--output", str(self.output), f"--baseline={baseline}"],
+            capture_output=True, text=True, encoding="utf-8",
+        )
+
+    def test_nonfinite_baseline_is_rejected_without_overwriting_output(self):
+        for baseline in ("nan", "inf", "-inf", "1e309"):
+            with self.subTest(baseline=baseline):
+                self.output.write_text("existing salary data\n", encoding="utf-8")
+                result = self.convert(baseline)
+                self.assertNotEqual(result.returncode, 0, result.stdout + result.stderr)
+                self.assertIn("--baseline", result.stderr)
+                self.assertIn("finite", result.stderr)
+                self.assertNotIn("Traceback", result.stderr)
+                self.assertEqual(self.output.read_text(encoding="utf-8"), "existing salary data\n")
+
+    def test_finite_custom_and_zero_baselines_are_preserved(self):
+        for baseline in ("150", "0"):
+            with self.subTest(baseline=baseline):
+                result = self.convert(baseline)
+                self.assertEqual(result.returncode, 0, result.stderr)
+                data = json.loads(self.output.read_text(encoding="utf-8"))
+                self.assertEqual(data["metadata"]["index_baseline"], float(baseline))

tools/convert_salary_excel.py

@@ -398,6 +398,9 @@ def main():
     )
     args = parser.parse_args()
 
+    if not math.isfinite(args.baseline):
+        parser.error("--baseline must be a finite number")
+
     excel_path = Path(args.excel_file)
     if not excel_path.exists():
         print(f"Error: File not found: {excel_path}", file=sys.stderr)