fix(job-key): fold Latin letters without an NFKD decomposition and add --audit --migrate (#637)

* fix(job-key): fold Latin letters without an NFKD decomposition and add --audit --migrate

Closes #537

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

* refactor(job-key): drop the redundant NFC before NFKD

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

* fix(job-key): extend the fold to ı ħ ĸ ŋ ŧ, ignore migrate backups, correct NFC wording

Fold the remaining Latin Extended-A letters without an NFKD decomposition
(ı→i, ħ/Ħ→h, ĸ→k, ŋ/Ŋ→ng, ŧ/Ŧ→t, per Unidecode 1.4.0), so "Kılıç" keys
as "kilic" instead of "klc". Gitignore the seen_jobs.json.bak-* backups
written by --audit --migrate and require the rule in security_guards.
The CHANGELOG and a test comment still described an NFC pass; the fold
runs after NFKD and there is no NFC.

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

* chore: drop the CHANGELOG hunk, frozen by #800 (release notes come from the PR title)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>
Co-authored-by: Mads Lorentzen <madslorentzen_17@hotmail.com>

.claude/skills/job-scraper/SKILL.md

@@ -157,7 +157,7 @@ For each new job, do a rapid fit check (NOT the full evaluation from `04-job-eva
 python3 tools/job_key.py --company "<company>" --title "<title>" --url "<url>"
 ```
 
-It prints one line: the canonical key for that posting. The key must be a pure function of the posting, because two runs that slugify differently store the same job twice and defeat the dedup this step exists to provide. The helper also length-caps long titles and disambiguates the cap with a hash of the full slug, so a truncated title is stable across runs and two different long titles never collide. `python3 tools/job_key.py --audit` reports entries in an existing state file that predate this rule; it only reports, and never rewrites keys, since a rewritten key breaks the tracker's own company+role matching.
+It prints one line: the canonical key for that posting. The key must be a pure function of the posting, because two runs that slugify differently store the same job twice and defeat the dedup this step exists to provide. The helper also length-caps long titles and disambiguates the cap with a hash of the full slug, so a truncated title is stable across runs and two different long titles never collide. `python3 tools/job_key.py --audit` reports entries in an existing state file that predate this rule; it only reports. `python3 tools/job_key.py --audit --migrate` rewrites the keys that no longer match the rule (backup first, old->new reported, an existing key is never overwritten, a second run changes nothing).
 
 2. Add ALL fetched jobs (new and skipped) to `job_scraper/seen_jobs.json` through the tool below. Each stored entry has this structure:
 ```json

.gitignore

@@ -25,6 +25,8 @@ salary_data.json
 # its own directory, so these land at .claude/skills/job-scraper/job_scraper/*.
 # A rooted `job_scraper/...` pattern silently fails to match them.
 **/job_scraper/seen_jobs.json
+# Backups written by `tools/job_key.py --audit --migrate` hold the same history.
+**/job_scraper/seen_jobs.json.bak-*
 **/job_scraper/notion_sync.json
 **/job_scraper/*.md
 *_BehavioralReport.pdf

tests/test_job_key.py

@@ -14,7 +14,7 @@ import unittest
 from pathlib import Path
 
 sys.path.insert(0, str(Path(__file__).resolve().parent.parent / "tools"))
-from job_key import is_canonical, is_legacy_shape, make_key, slugify  # noqa: E402
+from job_key import _LATIN_FOLD, is_canonical, is_legacy_shape, make_key, slugify  # noqa: E402
 
 REPO = Path(__file__).resolve().parent.parent
 TOOL = REPO / "tools" / "job_key.py"
@@ -159,12 +159,49 @@ class MixedScriptNamesKeepTheirIdentity(unittest.TestCase):
         # NFKD folds these without dropping a letter, so existing keys stay put.
         self.assertEqual(make_key("Zürich Versicherung", "Ingénieur finance"), "zurich-versicherung_ingenieur-finance")
 
-    def test_latin_letters_without_a_decomposition_do_not_re_key(self):
-        # "ø" and "æ" have no NFKD decomposition and are dropped by the fold,
-        # but they are Latin letters: "Ørsted" has keyed as "rsted" since the
-        # rule existed, and a live Danish seen_jobs.json must not re-key.
-        self.assertEqual(make_key("Ørsted A/S", "Senior Engineer"), "rsted-a-s_senior-engineer")
-        self.assertEqual(make_key("Mærsk", "Søfarende"), "mrsk_sfarende")
+    def test_latin_letters_without_a_decomposition_are_folded(self):
+        # "ø" and "æ" have no NFKD decomposition, so the ASCII fold used to drop
+        # them ("Mærsk" -> "mrsk"). #537 folds them through a table instead; a
+        # live seen_jobs.json is moved by `--audit --migrate`.
+        self.assertEqual(make_key("Ørsted A/S", "Senior Engineer"), "orsted-a-s_senior-engineer")
+        self.assertEqual(make_key("Mærsk", "Søfarende"), "maersk_sofarende")  # was mrsk_sfarende before #537
+
+    def test_ao_and_ro_no_longer_collide(self):
+        self.assertNotEqual(make_key("Ærø", "Pilot"), make_key("Rø", "Pilot"))
+        self.assertEqual(slugify("Ærø"), "aero")
+
+    def test_unchanged_letters_keep_their_keys(self):
+        self.assertEqual(slugify("Århus"), "arhus")  # å stays a, not aa
+        self.assertEqual(slugify("é"), "e")
+
+    def test_every_table_character_folds_including_capitals(self):
+        for ch, folded in _LATIN_FOLD.items():
+            with self.subTest(ch=ch):
+                self.assertEqual(slugify(f"x{ch}y"), f"x{folded.lower()}y")
+
+    def test_latin_extended_a_letters_fold_including_capitals(self):
+        cases = {
+            "ı": "i",
+            "ħ": "h", "Ħ": "h",
+            "ĸ": "k",
+            "ŋ": "ng", "Ŋ": "ng",
+            "ŧ": "t", "Ŧ": "t",
+        }
+        for ch, folded in cases.items():
+            with self.subTest(ch=ch):
+                self.assertEqual(slugify(f"x{ch}y"), f"x{folded}y")
+
+    def test_turkish_dotless_i_keeps_its_letters(self):
+        self.assertEqual(slugify("Kılıç"), "kilic")
+
+    def test_fold_applies_to_decomposed_input_too(self):
+        # "Å" typed as A + combining ring: NFKD keeps the A and the mark is dropped.
+        self.assertEqual(slugify("Århus"), "arhus")
+
+    def test_letter_that_decomposes_into_a_table_letter_is_folded(self):
+        # "ǿ" (U+01FF) is NFKD "ø" + acute, so the fold must run after NFKD.
+        self.assertEqual(slugify("ǿ"), "o")
+        self.assertEqual(slugify("Ǿ"), "o")
 
 
 class CompanyFallbackCLI(unittest.TestCase):
@@ -287,5 +324,128 @@ class AuditCLI(unittest.TestCase):
                 self.assertNotIn("Traceback", proc.stderr)
 
 
+class MigrateCLI(unittest.TestCase):
+    """`--audit --migrate` rewrites drifted keys in place, safely."""
+
+    OLD = "mrsk_sfarende"
+    NEW = "maersk_sofarende"
+
+    def setUp(self):
+        import tempfile
+
+        self._tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self._tmp.cleanup)
+        self.path = Path(self._tmp.name) / "seen_jobs.json"
+
+    def write(self, seen):
+        self.path.write_text(json.dumps({"seen": seen}, ensure_ascii=False), encoding="utf-8")
+
+    def migrate(self):
+        proc = subprocess.run(
+            [sys.executable, str(TOOL), "--audit", str(self.path), "--migrate"],
+            capture_output=True, text=True, encoding="utf-8",
+        )
+        return json.loads(proc.stdout), proc
+
+    def seen(self):
+        return json.loads(self.path.read_text(encoding="utf-8"))["seen"]
+
+    def backups(self):
+        return list(self.path.parent.glob("seen_jobs.json.bak-*"))
+
+    def test_rewrites_the_key_and_keeps_the_entry(self):
+        entry = {"company": "Mærsk", "title": "Søfarende", "status": "ranked"}
+        self.write({self.OLD: entry})
+        report, proc = self.migrate()
+        self.assertEqual(proc.returncode, 0)
+        self.assertEqual(self.seen(), {self.NEW: entry})
+        self.assertEqual(report["migrated"], [{"old": self.OLD, "new": self.NEW}])
+        self.assertEqual(report["keys_not_matching_current_rule"], 0)
+
+    def test_backup_holds_the_original_bytes(self):
+        self.write({self.OLD: {"company": "Mærsk", "title": "Søfarende"}})
+        original = self.path.read_bytes()
+        report, _ = self.migrate()
+        backups = self.backups()
+        self.assertEqual(len(backups), 1)
+        self.assertEqual(backups[0].read_bytes(), original)
+        self.assertEqual(report["backup"], str(backups[0]))
+
+    def test_existing_new_key_is_reported_not_overwritten(self):
+        existing = {"company": "Mærsk", "title": "Søfarende", "status": "applied"}
+        stale = {"company": "Mærsk", "title": "Søfarende", "status": "new"}
+        self.write({self.NEW: existing, self.OLD: stale})
+        report, _ = self.migrate()
+        self.assertEqual(self.seen(), {self.NEW: existing, self.OLD: stale})
+        self.assertEqual(report["migrate_collisions"], [{"old": self.OLD, "new": self.NEW}])
+        self.assertEqual(report["migrated"], [])
+        self.assertEqual(self.backups(), [])
+
+    def test_chain_moves_in_one_run_and_the_second_run_is_byte_identical(self):
+        # A is keyed "wrong", and today's key for A is x. B sits on x and today
+        # belongs on y. Moving B first frees x for A.
+        a = {"company": "Mærsk", "title": "Søfarende", "status": "new"}
+        b = {"company": "Ørsted", "title": "Engineer", "status": "applied"}
+        x = self.NEW
+        y = make_key("Ørsted", "Engineer")
+        self.write({"stale-a_x": a, x: b})  # file order: A first, so B must not block it
+        self.assertEqual(make_key("Mærsk", "Søfarende"), x)
+        report, _ = self.migrate()
+        self.assertEqual(self.seen(), {x: a, y: b})
+        self.assertEqual({m["old"]: m["new"] for m in report["migrated"]}, {"stale-a_x": x, x: y})
+        self.assertEqual(report["migrate_collisions"], [])
+        after = self.path.read_bytes()
+        again, _ = self.migrate()
+        self.assertEqual(again["migrated"], [])
+        self.assertEqual(self.path.read_bytes(), after)
+        self.assertEqual(len(self.backups()), 1)
+
+    def test_migrating_one_key_changes_only_the_lines_that_carry_it(self):
+        # Written the way tools/rank_state.save_state writes it.
+        seen = {
+            self.OLD: {"company": "Mærsk", "title": "Søfarende", "tags": ["a", "b"]},
+            "acme_soc": {"company": "Acme", "title": "SOC", "url": "https://x/1"},
+        }
+        text = json.dumps({"seen": seen}, indent=2, ensure_ascii=False) + chr(10)
+        self.path.write_text(text, encoding="utf-8")
+        self.migrate()
+        before, after = text.splitlines(), self.path.read_text(encoding="utf-8").splitlines()
+        self.assertEqual(len(before), len(after))
+        changed = [(o, n) for o, n in zip(before, after) if o != n]
+        self.assertEqual(len(changed), 1)
+        self.assertIn(self.OLD, changed[0][0])
+        self.assertIn(self.NEW, changed[0][1])
+
+    def test_second_run_changes_nothing(self):
+        self.write({self.OLD: {"company": "Mærsk", "title": "Søfarende"}, "acme_soc": {"company": "Acme", "title": "SOC"}})
+        self.migrate()
+        after_first = self.path.read_bytes()
+        report, _ = self.migrate()
+        self.assertEqual(report["migrated"], [])
+        self.assertEqual(self.path.read_bytes(), after_first)
+        self.assertEqual(len(self.backups()), 1)
+
+    def test_no_drift_writes_no_backup(self):
+        self.write({"acme_soc": {"company": "Acme", "title": "SOC"}})
+        before = self.path.read_bytes()
+        report, _ = self.migrate()
+        self.assertEqual(report["migrated"], [])
+        self.assertEqual(self.path.read_bytes(), before)
+        self.assertEqual(self.backups(), [])
+
+    def test_audit_alone_never_rewrites(self):
+        self.write({self.OLD: {"company": "Mærsk", "title": "Søfarende"}})
+        before = self.path.read_bytes()
+        proc = subprocess.run(
+            [sys.executable, str(TOOL), "--audit", str(self.path)], capture_output=True, text=True, encoding="utf-8"
+        )
+        self.assertEqual(json.loads(proc.stdout)["keys_not_matching_current_rule"], 1)
+        self.assertEqual(self.path.read_bytes(), before)
+
+    def test_migrate_without_audit_is_a_usage_error(self):
+        proc = subprocess.run([sys.executable, str(TOOL), "--migrate"], capture_output=True, text=True, encoding="utf-8")
+        self.assertEqual(proc.returncode, 2)
+
+
 if __name__ == "__main__":
     unittest.main()

tools/job_key.py

@@ -36,6 +36,11 @@ readable prefix and the identity comes from the same fallback.
 Usage:
   python3 tools/job_key.py --company "Acme Corp" --title "SOC Analyst (L2)"
   python3 tools/job_key.py --audit job_scraper/seen_jobs.json
+  python3 tools/job_key.py --audit --migrate
+
+`--audit --migrate` rewrites keys that no longer match the current rule, in
+place: backup first, old->new reported, a new key that already exists is
+reported and left alone, and a second run changes nothing.
 
 Exit 0 when a key is produced, or when an audit finds nothing. Exit 1 when an
 audit finds violations.
@@ -44,9 +49,13 @@ audit finds violations.
 import argparse
 import hashlib
 import json
+import os
 import re
+import shutil
 import sys
+import tempfile
 import unicodedata
+from datetime import datetime
 from pathlib import Path
 
 ROOT = Path(__file__).resolve().parent.parent
@@ -63,12 +72,39 @@ _NON_SLUG = re.compile(r"[^a-z0-9]+")
 _JOB_ID = re.compile(r"(\d{6,})")
 
 
+# Latin letters with no NFKD decomposition, which the ASCII fold would otherwise
+# drop ("Ørsted" keyed as "rsted", "Mærsk" as "mrsk", "Kılıç" as "klc"). Values
+# follow Unidecode 1.4.0; ICU's Latin-ASCII differs only on "ĸ" (q) and "ŋ" (n).
+# "ĸ" and "ı" have no table capital: "ĸ" has none and "ı"'s is plain "I".
+# "å" is deliberately absent: it decomposes to "a" plus a ring without losing a
+# letter, and "å"->"aa" would move keys that work today for no gain (#537).
+_LATIN_FOLD = {
+    "ø": "o", "Ø": "O",
+    "æ": "ae", "Æ": "AE",
+    "œ": "oe", "Œ": "OE",
+    "ß": "ss", "ẞ": "SS",
+    "þ": "th", "Þ": "TH",
+    "ð": "d", "Ð": "D",
+    "đ": "d", "Đ": "D",
+    "ł": "l", "Ł": "L",
+    "ı": "i",
+    "ħ": "h", "Ħ": "H",
+    "ĸ": "k",
+    "ŋ": "ng", "Ŋ": "NG",
+    "ŧ": "t", "Ŧ": "T",
+}
+_LATIN_FOLD_TABLE = str.maketrans(_LATIN_FOLD)
+
+
 def slugify(text: str) -> str:
     """Lowercase ASCII slug. Non-Latin scripts legitimately reduce to ''."""
     if not text:
         return ""
+    # Fold after NFKD so a letter that decomposes into a fold-table letter plus
+    # a mark ("ǿ" -> "ø" + acute) is folded too.
     decomposed = unicodedata.normalize("NFKD", str(text))
-    ascii_only = decomposed.encode("ascii", "ignore").decode("ascii")
+    folded = decomposed.translate(_LATIN_FOLD_TABLE)
+    ascii_only = folded.encode("ascii", "ignore").decode("ascii")
     return _NON_SLUG.sub("-", ascii_only.lower()).strip("-")
 
 
@@ -81,9 +117,8 @@ def _lost_letters(text: str) -> bool:
     its Latin or digit fragment, and two different names can share it.
 
     Latin letters that also lack a decomposition ("ø", "æ", "ß", "ł") are
-    deliberately NOT counted: "Ørsted" has keyed as "rsted" since the rule
-    existed, and treating it as lossy would re-key every Danish company in a
-    live seen_jobs.json for a collision that does not happen in practice.
+    not counted: slugify folds them through _LATIN_FOLD ("ø" -> "o"), so they
+    keep their letter and are not lossy.
     """
     if not text:
         return False
@@ -177,24 +212,125 @@ def is_legacy_shape(key: str) -> bool:
     )
 
 
-def audit(path: Path) -> int:
+def _load_seen(path: Path):
+    """Return (document, seen) or print the reason and return None."""
     try:
         doc = json.loads(path.read_text(encoding="utf-8"))
     except (OSError, json.JSONDecodeError) as exc:
         print(f"cannot read {path}: {exc}", file=sys.stderr)
-        return 1
+        return None
     seen = doc.get("seen", doc) if isinstance(doc, dict) else doc
     if not isinstance(seen, dict):
         print(f"{path}: expected an object of job entries", file=sys.stderr)
-        return 1
+        return None
     not_objects = [k for k, v in seen.items() if not isinstance(v, dict)]
     if not_objects:
         print(f"{path}: entry is not an object: {not_objects[0]}", file=sys.stderr)
-        return 1
+        return None
     bad_url = [k for k, v in seen.items() if v.get("url") is not None and not isinstance(v["url"], str)]
     if bad_url:
         print(f"{path}: entry url is not a string: {bad_url[0]}", file=sys.stderr)
+        return None
+    return doc, seen
+
+
+def _drifted(seen: dict) -> list[str]:
+    """Canonical keys that differ from what make_key would produce today."""
+    return [
+        k for k, v in seen.items()
+        if is_canonical(k) and k != make_key(v.get("company", ""), v.get("title", ""), v.get("url", ""))
+    ]
+
+
+def _rename_pass(seen: dict) -> tuple[dict[str, str], list[dict]]:
+    """One pass: which drifted keys can move, and which are blocked.
+
+    A key is blocked when its new key is held by an entry that does not itself
+    move in this pass, or when an earlier entry (file order) claims the same
+    new key. A blocked entry stays put, which can in turn block another, so
+    the movers are narrowed until the set is stable. An entry whose new key is
+    held by a mover is fine: the chain A -> x, B(on x) -> y moves together.
+    """
+    target = {
+        k: make_key(seen[k].get("company", ""), seen[k].get("title", ""), seen[k].get("url", ""))
+        for k in _drifted(seen)
+    }
+    movers = dict(target)
+    blocked: dict[str, str] = {}
+    changed = True
+    while changed:
+        changed = False
+        claimed: set[str] = set()
+        for old, new in list(movers.items()):
+            if (new in seen and new not in movers) or new in claimed:
+                blocked[old] = new
+                del movers[old]
+                changed = True
+            else:
+                claimed.add(new)
+    return movers, [{"old": o, "new": n} for o, n in blocked.items()]
+
+
+def migrate(path: Path, doc, seen: dict) -> dict:
+    """Rewrite drifted keys in place; return the report.
+
+    Runs passes until nothing renames. Deterministic (file order decides which
+    of two entries claims a new key), never overwrites an existing key, and
+    idempotent: once every rewritable key is current, a second run finds
+    nothing to change and writes nothing. Collisions in the report are the
+    final ones only.
+    """
+    current = dict(seen)
+    migrated: list[dict] = []
+    collisions: list[dict] = []
+    for _ in range(len(seen) + 1):
+        renames, collisions = _rename_pass(current)
+        if not renames:
+            break
+        migrated.extend({"old": o, "new": n} for o, n in renames.items())
+        current = {renames.get(k, k): v for k, v in current.items()}
+    report = {
+        "migrated": migrated,
+        "migrate_collisions": collisions,
+        "backup": None,
+    }
+    if not migrated:
+        return report
+
+    backup = path.with_name(f"{path.name}.bak-{datetime.now():%Y%m%d-%H%M%S}")
+    shutil.copy2(path, backup)
+    report["backup"] = str(backup)
+
+    out = dict(doc, seen=current) if isinstance(doc, dict) and "seen" in doc else current
+    # Same dump settings as tools/rank_state.save_state, so a migration changes
+    # only the lines that carry a renamed key. Atomic replace: a half-written
+    # seen_jobs.json loses the scrape history.
+    fd, tmp = tempfile.mkstemp(dir=str(path.parent), prefix=f".{path.name}.", suffix=".tmp")
+    try:
+        with os.fdopen(fd, "w", encoding="utf-8") as fh:
+            json.dump(out, fh, indent=2, ensure_ascii=False)
+            fh.write("\n")
+        os.replace(tmp, path)
+    except BaseException:
+        Path(tmp).unlink(missing_ok=True)
+        raise
+    return report
+
+
+def audit(path: Path, do_migrate: bool = False) -> int:
+    loaded = _load_seen(path)
+    if loaded is None:
         return 1
+    doc, seen = loaded
+
+    migration = {}
+    if do_migrate:
+        migration = migrate(path, doc, seen)
+        if migration["migrated"]:
+            loaded = _load_seen(path)
+            if loaded is None:
+                return 1
+            doc, seen = loaded
 
     malformed = [k for k in seen if not is_canonical(k) and not is_legacy_shape(k)]
     legacy = [k for k in seen if is_legacy_shape(k)]
@@ -205,11 +341,8 @@ def audit(path: Path) -> int:
             by_url.setdefault(url, []).append(key)
     duplicates = {u: ks for u, ks in by_url.items() if len(ks) > 1}
     # A key that does not match what make_key would produce today is drift, not
-    # damage: reported separately so a rename is a choice, never automatic.
-    drift = [
-        k for k, v in seen.items()
-        if is_canonical(k) and k != make_key(v.get("company", ""), v.get("title", ""), v.get("url", ""))
-    ]
+    # damage: reported separately so a rename is a choice (--migrate), never automatic.
+    drift = _drifted(seen)
 
     print(json.dumps({
         "entries": len(seen),
@@ -217,6 +350,7 @@ def audit(path: Path) -> int:
         "legacy_three_part_keys": legacy,
         "duplicate_urls": duplicates,
         "keys_not_matching_current_rule": len(drift),
+        **migration,
     }, indent=2, ensure_ascii=False))
     return 1 if (malformed or duplicates) else 0
 
@@ -241,10 +375,13 @@ def main() -> int:
     ap.add_argument("--title")
     ap.add_argument("--url", default="")
     ap.add_argument("--audit", nargs="?", const=str(STATE), metavar="STATE_JSON")
+    ap.add_argument("--migrate", action="store_true", help="with --audit: rewrite drifted keys in place (backup first)")
     args = ap.parse_args()
 
+    if args.migrate and not args.audit:
+        ap.error("--migrate needs --audit")
     if args.audit:
-        return audit(Path(args.audit))
+        return audit(Path(args.audit), args.migrate)
     if args.company is None or args.title is None:
         ap.error("give --company and --title, or --audit")
     print(make_key(args.company, args.title, args.url))

tools/security_guards.py

@@ -168,6 +168,7 @@ REQUIRED_IGNORE_RULES = [
     # to its own directory, so the state file lands under .claude/skills/... and
     # a repo-rooted rule silently fails to match it.
     "**/job_scraper/seen_jobs.json",
+    "**/job_scraper/seen_jobs.json.bak-*",
     "**/job_scraper/notion_sync.json",
     "**/job_scraper/*.md",
     "*_BehavioralReport.pdf",