fix(salary-tools): decide number locale by last separator, pair compound headers

Review findings F7 and F8 (2026-08-19):

- parse_numeric_cell's both-separators branch always assumed European
  locale, silently turning a US "1,234.56" into 1.23456 - a 1000x
  corruption written to salary_data.json with no warning. The separator
  that appears last is now treated as the decimal separator, which also
  makes multi-group values ("1,234,567.89") parse instead of raising a
  raw float error. Single-separator ambiguity guards are unchanged.

- strip_type_patterns stripped only whole tokens, so the compound header
  "Lønindeks alle" kept its type word and could never pair with "Antal
  alle" - failing exactly for the compound-word locale COMPOUND_PATTERNS
  exists to support. It now also strips compound patterns as substrings,
  mirroring header_matches.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -56,6 +56,16 @@ per-file diff commands.
 
 ### Fixed
 
+- **`convert_salary_excel.py` no longer corrupts US/UK-formatted numbers 1000x** - the
+  both-separators branch always assumed European locale, so a `"1,234.56"` cell was
+  silently converted to `1.23456` and written into `salary_data.json`. The rule is now
+  "the separator that appears last is the decimal separator", which also makes
+  multi-group values (`"1,234,567.89"`, `"1.234.567,89"`) parse instead of raising. And
+  `strip_type_patterns` now strips `COMPOUND_PATTERNS` words as substrings, mirroring
+  `header_matches`, so a Danish compound header pair ("Antal alle" / "Lønindeks alle")
+  pairs into one category instead of two unpaired standalones - the exact locale the
+  compound support was added for. Pinned by six new cases in
+  `tests/test_convert_salary_excel.py`.
 - **`jobdanmark-search` extracts the city when a comma follows the postcode** - the
   `location` regex required whitespace after the 4-digit postcode, but live
   `companyAddress` values frequently read `"2670, Greve"`; those results emitted

tests/test_convert_salary_excel.py

@@ -5,6 +5,7 @@ from tools.convert_salary_excel import (
     INDEX_PATTERNS,
     detect_column_type,
     header_matches,
+    parse_numeric_cell,
     parse_sheet,
 )
 
@@ -288,3 +289,54 @@ class DetectColumnTypeTests(unittest.TestCase):
 
 if __name__ == "__main__":
     unittest.main()
+
+
+class ParseNumericCellLocaleTests(unittest.TestCase):
+    # The separator that appears LAST is the decimal separator. Assuming
+    # European ("." thousands, "," decimal) for every both-separator string
+    # turned a US "1,234.56" into 1.23456 - a silent 1000x corruption that
+    # flowed into salary_data.json and negotiation advice.
+
+    def test_us_thousands_and_decimal_string(self):
+        self.assertEqual(parse_numeric_cell("1,234.56"), 1234.56)
+
+    def test_us_multiple_thousands_groups(self):
+        self.assertEqual(parse_numeric_cell("1,234,567.89"), 1234567.89)
+
+    def test_european_thousands_and_decimal_string(self):
+        self.assertEqual(parse_numeric_cell("1.234,56"), 1234.56)
+
+    def test_european_multiple_thousands_groups(self):
+        self.assertEqual(parse_numeric_cell("1.234.567,89"), 1234567.89)
+
+
+class CompoundCategoryPairingTests(unittest.TestCase):
+    def test_parse_sheet_pairs_danish_compound_index_with_count(self):
+        # "Lønindeks alle" is *detected* as an index column via
+        # COMPOUND_PATTERNS, but the derived category name must also lose the
+        # compound word or it can never pair with "Antal alle" ("alle" vs
+        # "lønindeks alle") - exactly the locale the compound support exists for.
+        ws = FakeWorksheet([
+            ("Firma", "Antal alle", "Lønindeks alle"),
+            ("Example Corp", 12, 118.0),
+        ])
+
+        companies = parse_sheet(ws)
+
+        self.assertEqual(
+            companies[0]["categories"]["alle"],
+            {"count": 12, "index": 118.0},
+        )
+
+    def test_parse_sheet_sheet_level_us_locale_value(self):
+        ws = FakeWorksheet([
+            ("Company", "Salary Index"),
+            ("Example Corp", "1,234.56"),
+        ])
+
+        companies = parse_sheet(ws)
+
+        self.assertEqual(
+            companies[0]["categories"]["salary_index"],
+            {"index": 1234.56},
+        )

tools/convert_salary_excel.py

@@ -65,7 +65,13 @@ def parse_numeric_cell(value):
     if not text:
         raise ValueError("not numeric")
     if "," in text and "." in text:
+        # The separator that appears last is the decimal separator: European
+        # "1.234,56" and US "1,234.56" are both unambiguous here, unlike the
+        # single-separator cases below.
+        if text.rfind(",") > text.rfind("."):
             text = text.replace(".", "").replace(",", ".")
+        else:
+            text = text.replace(",", "")
     elif "," in text:
         if re.fullmatch(r"[+-]?\d+,\d{3}", text):
             raise ValueError("ambiguous comma separator")
@@ -95,10 +101,18 @@ def header_matches(header, patterns):
 
 
 def strip_type_patterns(header, patterns):
-    """Remove count/index words from a header to derive a category name."""
+    """Remove count/index words from a header to derive a category name.
+
+    Mirrors ``header_matches``: patterns strip as whole tokens, and any
+    pattern also listed in ``COMPOUND_PATTERNS`` additionally strips as a
+    substring - otherwise a compound header like "Lønindeks alle" keeps the
+    type word in its category name and can never pair with "Antal alle".
+    """
     name = header.lower()
     for p in patterns:
         name = re.sub(rf"(?<![a-zæøåöäü0-9]){re.escape(p)}(?![a-zæøåöäü0-9])", "", name)
+        if p in COMPOUND_PATTERNS:
+            name = name.replace(p, "")
     return name.strip(" _-")