refactor: dedup, consolidate, harden public APIs across core modules

Closes 16 high-value findings from a parallel cross-module review.

Refactors:
- New src/core/_constants.py centralizes USPS street-suffix
  abbreviations, US state names, and 2-letter postal codes — one source
  of truth for both normalize_address (matching keys) and
  standardize_address (display formatting). Eliminates ~80 lines of
  duplicated dicts across normalizers.py and format_standardize.py.
- format_standardize.py: collapse 4 identical nested _err() helpers
  into one shared _err_or_passthrough() module function; drop a dead
  duplicate `return _err("not a phone number")` branch in
  standardize_phone.
- format_standardize.py: precompile per-locale month-name regexes
  (_MONTH_LOCALE_PATTERNS) and per-state-name regexes
  (_STATE_NAME_PATTERNS) at import time — they were rebuilt on every
  cell, a measurable hot path on million-row inputs.
- dedup.py: extract _is_missing(value) helper; one definition of
  "this cell is None / NaN / pd.NA" instead of two.
- fixes.py: extract _is_string_column(ser) helper; one dtype check
  instead of three duplicates across _apply_to_strings,
  _vectorized_translate, _vectorized_regex_sub.

Production-readiness:
- format_standardize.standardize_dataframe now logs a warning when
  more than 10% of typed cells are unparseable — surfaces the
  silently-broken-pipeline failure mode.
- StandardizeOptions.from_dict validates date_order / phone_format /
  currency_decimal / name_case / boolean_style / *_error_policy
  enum values up front, with a clear error message instead of a deep
  crash inside the per-cell function.
- StandardizeOptions.from_file and DeduplicationConfig.from_file wrap
  read + json.loads with descriptive OSError / ValueError messages
  including the file path.
- standardize_date(month_locales=...) validates locale codes against
  the available set instead of silently passing through unknown ones.
- io.read_file rejects chunk_size <= 0 (was silently failing inside
  pandas) and logs the resolved suffix + chunk_size at info level so
  data-pipeline runs are debuggable.
- io.read_file's FileNotFoundError gains explanatory context.
- io.write_file, text_clean.clean_dataframe, and dedup.deduplicate
  now reject non-DataFrame inputs with clear TypeError instead of
  cryptic pandas tracebacks downstream.
- dedup.deduplicate validates that survivor_rule=KEEP_MOST_RECENT has
  a usable date_column up front; the helper _select_survivor now
  raises (instead of silently falling back to keep_first) when called
  directly with bad arguments.
- dedup.deduplicate gains a structured no-op return when strategies
  is empty after auto-detection — preserves schema instead of crashing.
- analyze._detect_inconsistent_date_format narrows its bare except to
  (TypeError, ValueError) and logs a debug line so genuine bugs don't
  hide behind silent skip.

Tests:
- tests/test_audit_fixes.py grows by 11 cases covering the new
  validation paths (chunk_size, DataFrame guards, KEEP_MOST_RECENT
  date_column, enum validation, locale validation, JSON error wrapping).

Full project suite: 1208 passed, 4 skipped, 17 xfailed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/core/_constants.py

@@ -0,0 +1,103 @@
+"""Shared lookup tables used by both the dedup-side normalizers and the
+display-side format standardizer.
+
+Both modules need the same authoritative mapping of US state names →
+2-letter postal codes and USPS street-suffix abbreviations. Keeping a
+single source of truth avoids the bug-class where the two layers drift
+("Drive" → "Dr" in one but "Drv" in the other).
+
+Per-module aliases (``_US_STATE_NAMES_NORM`` lowercase-only for matching
+keys vs. ``_US_STATE_NAMES`` casefold-on-lookup for display) are still
+defined locally to preserve historical behavior; both derive from the
+canonical maps below.
+"""
+
+from __future__ import annotations
+
+# US state name (lowercase) → 2-letter postal code.
+US_STATE_NAMES: dict[str, str] = {
+    "alabama": "AL", "alaska": "AK", "arizona": "AZ", "arkansas": "AR",
+    "california": "CA", "colorado": "CO", "connecticut": "CT",
+    "delaware": "DE", "florida": "FL", "georgia": "GA", "hawaii": "HI",
+    "idaho": "ID", "illinois": "IL", "indiana": "IN", "iowa": "IA",
+    "kansas": "KS", "kentucky": "KY", "louisiana": "LA", "maine": "ME",
+    "maryland": "MD", "massachusetts": "MA", "michigan": "MI",
+    "minnesota": "MN", "mississippi": "MS", "missouri": "MO",
+    "montana": "MT", "nebraska": "NE", "nevada": "NV",
+    "new hampshire": "NH", "new jersey": "NJ", "new mexico": "NM",
+    "new york": "NY", "north carolina": "NC", "north dakota": "ND",
+    "ohio": "OH", "oklahoma": "OK", "oregon": "OR", "pennsylvania": "PA",
+    "rhode island": "RI", "south carolina": "SC", "south dakota": "SD",
+    "tennessee": "TN", "texas": "TX", "utah": "UT", "vermont": "VT",
+    "virginia": "VA", "washington": "WA", "west virginia": "WV",
+    "wisconsin": "WI", "wyoming": "WY",
+    "district of columbia": "DC",
+}
+
+# 2-letter US state postal codes (incl. territories). The placeholder
+# code "ST" appears in the corpus fixtures; preserved here so the
+# standardizer doesn't expand it as a Street abbreviation.
+US_STATE_CODES: frozenset[str] = frozenset({
+    "AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "FL", "GA",
+    "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD",
+    "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ",
+    "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC",
+    "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY",
+    "DC", "PR", "VI", "GU", "AS", "MP",
+    "ST",
+})
+
+# Long-form → USPS-canonical short form (compression). Used by the
+# format standardizer when ``expand=False`` and by normalize_address
+# when reducing to a matching key.
+USPS_COMPRESSIONS: dict[str, str] = {
+    "street": "St", "avenue": "Ave", "boulevard": "Blvd",
+    "drive": "Dr", "lane": "Ln", "road": "Rd", "court": "Ct",
+    "place": "Pl", "circle": "Cir", "trail": "Trl", "terrace": "Ter",
+    "parkway": "Pkwy", "highway": "Hwy", "expressway": "Expy",
+    "freeway": "Fwy", "square": "Sq", "alley": "Aly",
+    "crossing": "Xing", "point": "Pt",
+    "north": "N", "south": "S", "east": "E", "west": "W",
+    "northeast": "NE", "northwest": "NW", "southeast": "SE",
+    "southwest": "SW",
+    "apartment": "Apt", "suite": "Ste", "building": "Bldg",
+    "floor": "Fl", "room": "Rm", "fort": "Ft", "mount": "Mt",
+    "heights": "Hts", "springs": "Spgs",
+}
+
+# Abbreviation → expansion (the inverse of USPS_COMPRESSIONS, plus a
+# handful of legacy aliases like ``av`` → ``Avenue``). Used by the
+# format standardizer when ``expand=True`` (default).
+USPS_EXPANSIONS: dict[str, str] = {
+    "st": "Street",
+    "ave": "Avenue", "av": "Avenue",
+    "blvd": "Boulevard", "blv": "Boulevard",
+    "dr": "Drive",
+    "ln": "Lane",
+    "rd": "Road",
+    "ct": "Court",
+    "pl": "Place",
+    "cir": "Circle",
+    "trl": "Trail", "tr": "Trail",
+    "ter": "Terrace",
+    "pkwy": "Parkway",
+    "hwy": "Highway",
+    "expy": "Expressway",
+    "fwy": "Freeway",
+    "sq": "Square",
+    "aly": "Alley",
+    "xing": "Crossing",
+    "pt": "Point",
+    "n": "North", "s": "South", "e": "East", "w": "West",
+    "ne": "Northeast", "nw": "Northwest",
+    "se": "Southeast", "sw": "Southwest",
+    "apt": "Apartment",
+    "ste": "Suite",
+    "bldg": "Building",
+    "fl": "Floor",
+    "rm": "Room",
+    "ft": "Fort",
+    "mt": "Mount",
+    "hts": "Heights",
+    "spgs": "Springs",
+}

src/core/analyze.py

@@ -20,6 +20,7 @@ from pathlib import Path
 from typing import Any, Iterable, Literal, Optional
 
 import pandas as pd
+from loguru import logger
 from pandas.api import types as pdtypes
 
 from .io import RepairResult, repair_bytes, detect_encoding, detect_delimiter
@@ -384,7 +385,14 @@ def _detect_inconsistent_date_format(df: pd.DataFrame) -> list[Finding]:
     for col in df.columns:
         try:
             ser = df[col].dropna().astype(str)
-        except Exception:
+        except (TypeError, ValueError) as e:
+            # Some pandas extension dtypes (e.g., custom Decimal arrays)
+            # can refuse string coercion. Skip those columns but log the
+            # reason so a real bug doesn't hide behind silent skip.
+            logger.debug(
+                "date-format detector: skipping {!r} ({}): {}",
+                col, type(e).__name__, e,
+            )
             continue
         nonempty = ser[ser.str.strip().astype(bool)]
         if len(nonempty) < 4:

src/core/config.py

@@ -86,7 +86,19 @@ class DeduplicationConfig:
     @classmethod
     def from_file(cls, path: str | Path) -> DeduplicationConfig:
         """Load configuration from a JSON file."""
-        data = json.loads(Path(path).read_text())
+        path = Path(path)
+        try:
+            text = path.read_text()
+        except OSError as e:
+            raise OSError(
+                f"Could not read DeduplicationConfig from {path}: {e}"
+            ) from e
+        try:
+            data = json.loads(text)
+        except json.JSONDecodeError as e:
+            raise ValueError(
+                f"Invalid JSON in DeduplicationConfig file {path}: {e}"
+            ) from e
         return cls.from_dict(data)
 
     @classmethod

src/core/dedup.py

@@ -13,7 +13,7 @@ from __future__ import annotations
 import re
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import Callable, Optional
+from typing import Any, Callable, Optional
 
 import pandas as pd
 from loguru import logger
@@ -162,6 +162,23 @@ def _compute_similarity(val_a: str, val_b: str, algorithm: Algorithm) -> float:
 # Pair comparison
 # ---------------------------------------------------------------------------
 
+def _is_missing(value: Any) -> bool:
+    """True for None, NaN, or pd.NA — used everywhere we need to treat
+    a cell as "absent" rather than as the string ``"None"`` or ``"nan"``.
+
+    Centralizing the check avoids the silent-merge bug where
+    ``str(None)`` and ``str(nan)`` would both compare equal to themselves
+    and produce a false 100% match in the deduplicator.
+    """
+    if value is None:
+        return True
+    if value is pd.NA:
+        return True
+    if isinstance(value, float) and pd.isna(value):
+        return True
+    return False
+
+
 def _compare_pair(
     row_a: pd.Series,
     row_b: pd.Series,
@@ -180,18 +197,8 @@ def _compare_pair(
         raw_a = row_a.get(col, "")
         raw_b = row_b.get(col, "")
 
-        # NaN / None always count as "empty" — never as the literal
+        va = "" if _is_missing(raw_a) else str(raw_a)
-        # string "None" or "nan", which would otherwise let two rows
+        vb = "" if _is_missing(raw_b) else str(raw_b)
-        # with missing data in this column match at 100% similarity.
-        a_missing = raw_a is None or (
-            isinstance(raw_a, float) and pd.isna(raw_a)
-        ) or raw_a is pd.NA
-        b_missing = raw_b is None or (
-            isinstance(raw_b, float) and pd.isna(raw_b)
-        ) or raw_b is pd.NA
-
-        va = "" if a_missing else str(raw_a)
-        vb = "" if b_missing else str(raw_b)
 
         # Skip if both empty
         if not va and not vb:
@@ -324,8 +331,14 @@ def _select_survivor(
 
     if rule == SurvivorRule.KEEP_MOST_RECENT:
         if not date_column or date_column not in df.columns:
-            logger.warning("date_column '{}' not found; falling back to keep_first", date_column)
+            # The public ``deduplicate()`` validates this earlier, so
-            return indices[0]
+            # reaching here means a caller invoked the helper directly
+            # with bad arguments — surface a clear error instead of a
+            # silent fallback that produces wrong-but-plausible output.
+            raise ValueError(
+                f"KEEP_MOST_RECENT requires date_column to be a column in df; "
+                f"got {date_column!r} (available: {list(df.columns)})"
+            )
         best_idx = indices[0]
         best_date = _parse_date(df.iloc[indices[0]].get(date_column, ""))
         for idx in indices[1:]:
@@ -504,6 +517,24 @@ def deduplicate(
 
     Returns a ``DeduplicationResult``.
     """
+    if not isinstance(df, pd.DataFrame):
+        raise TypeError(
+            f"deduplicate() requires a pandas DataFrame; got {type(df).__name__}"
+        )
+    if survivor_rule == SurvivorRule.KEEP_MOST_RECENT and not date_column:
+        raise ValueError(
+            "survivor_rule=KEEP_MOST_RECENT requires date_column to be set"
+        )
+    if (
+        survivor_rule == SurvivorRule.KEEP_MOST_RECENT
+        and date_column
+        and date_column not in df.columns
+    ):
+        raise ValueError(
+            f"date_column={date_column!r} not found in input. "
+            f"Available columns: {list(df.columns)}"
+        )
+
     log_entries: list[str] = []
     original_count = len(df)
 
@@ -511,6 +542,19 @@ def deduplicate(
         strategies = build_default_strategies(df)
         log_entries.append(f"Auto-detected {len(strategies)} match strategies")
 
+    if not strategies:
+        # Empty input or no detectable strategies — return the input
+        # unchanged with an empty match result, structurally consistent.
+        logger.info("deduplicate: no strategies, returning input unchanged")
+        return DeduplicationResult(
+            original_row_count=original_count,
+            deduplicated_df=df.reset_index(drop=True),
+            removed_df=df.iloc[0:0].copy().reset_index(drop=True),
+            match_groups=[],
+            log_entries=log_entries + ["No strategies → no-op"],
+            is_preview=preview,
+        )
+
     # Validate every strategy references real columns — silent skip
     # would let a typo (``e_mail`` instead of ``email``) produce a
     # confidently-empty result.

src/core/fixes.py

@@ -78,6 +78,19 @@ def available_actions() -> list[str]:
 # Helpers
 # ---------------------------------------------------------------------------
 
+def _is_string_column(ser: pd.Series) -> bool:
+    """Return True for object- or pandas-string-typed Series.
+
+    Centralizes the dtype check so the three column-mutating helpers
+    (``_apply_to_strings``, ``_vectorized_translate``,
+    ``_vectorized_regex_sub``) stay in sync if the rule changes.
+    """
+    return (
+        pd.api.types.is_object_dtype(ser)
+        or pd.api.types.is_string_dtype(ser)
+    )
+
+
 def _apply_to_strings(
     df: pd.DataFrame, fn: Callable[[str], str], *, include_headers: bool = False,
     inplace: bool = False,
@@ -101,7 +114,7 @@ def _apply_to_strings(
     changed = 0
     for col in out.columns:
         ser = out[col]
-        if not (pd.api.types.is_object_dtype(ser) or pd.api.types.is_string_dtype(ser)):
+        if not _is_string_column(ser):
             continue
         # ``map`` skips non-string cells via the lambda guard. We compare
         # the original column to the transformed one for a single mask
@@ -139,7 +152,7 @@ def _vectorized_translate(
     changed = 0
     for col in out.columns:
         ser = out[col]
-        if not (pd.api.types.is_object_dtype(ser) or pd.api.types.is_string_dtype(ser)):
+        if not _is_string_column(ser):
             continue
         new_col = ser.where(~ser.map(lambda v: isinstance(v, str)), ser.str.translate(trans))
         delta = int((new_col != ser).sum())
@@ -167,7 +180,7 @@ def _vectorized_regex_sub(
     changed = 0
     for col in out.columns:
         ser = out[col]
-        if not (pd.api.types.is_object_dtype(ser) or pd.api.types.is_string_dtype(ser)):
+        if not _is_string_column(ser):
             continue
         new_col = ser.astype("string").str.replace(pattern, repl, regex=True).astype(object).fillna(ser)
         delta = int((new_col != ser).sum())
@@ -307,7 +320,7 @@ def lowercase_email(df: pd.DataFrame, payload: Optional[dict] = None) -> tuple[p
         if col not in out.columns:
             continue
         ser = out[col]
-        if not (pd.api.types.is_object_dtype(ser) or pd.api.types.is_string_dtype(ser)):
+        if not _is_string_column(ser):
             continue
         new_col = ser.map(lambda v: v.lower() if isinstance(v, str) else v)
         delta = int((new_col != ser).sum())

src/core/format_standardize.py

@@ -23,6 +23,8 @@ from __future__ import annotations
 
 import json
 import re
+
+from loguru import logger
 from dataclasses import asdict, dataclass, field
 from datetime import datetime, timedelta
 from enum import Enum
@@ -51,6 +53,19 @@ class FieldType(str, Enum):
     EMAIL = "email"
 
 
+# Shared error-policy helper used by every per-domain standardizer.
+# Returns ``(<error: reason>, changed)`` under the ``"sentinel"`` policy
+# and ``(value, False)`` under ``"passthrough"`` so unparseable input
+# survives unchanged.
+def _err_or_passthrough(
+    reason: str, value: str, policy: str,
+) -> tuple[str, bool]:
+    if policy == "sentinel":
+        sentinel = f"<error: {reason}>"
+        return sentinel, sentinel != value
+    return value, False
+
+
 # ---------------------------------------------------------------------------
 # Date
 # ---------------------------------------------------------------------------
@@ -153,24 +168,49 @@ _MONTH_LOCALES: dict[str, dict[str, str]] = {
 }
 
 
+def _build_month_locale_patterns() -> dict[str, list[tuple["re.Pattern[str]", str]]]:
+    """Precompile per-locale (pattern, replacement) lists once at import.
+
+    The previous loop compiled every pattern for every input cell — at
+    millions of rows that's a measurable hot spot.
+    """
+    out: dict[str, list[tuple[re.Pattern[str], str]]] = {}
+    for loc, table in _MONTH_LOCALES.items():
+        out[loc] = [
+            (
+                re.compile(
+                    rf"(?<![A-Za-z]){re.escape(foreign)}(?![A-Za-z])",
+                    re.IGNORECASE,
+                ),
+                english,
+            )
+            for foreign, english in table.items()
+        ]
+    return out
+
+
+_MONTH_LOCALE_PATTERNS = _build_month_locale_patterns()
+
+
 def _apply_month_locale(s: str, locales: list[str]) -> str:
-    """Replace localized month names with English equivalents."""
+    """Replace localized month names with English equivalents.
+
+    Raises ``ValueError`` if any locale is unrecognized — silent skip
+    would mask typos like ``"FR"`` (uppercase) or ``"french"``.
+    """
+    unknown = [
+        loc for loc in locales if loc != "en" and loc not in _MONTH_LOCALES
+    ]
+    if unknown:
+        raise ValueError(
+            f"Unknown month locale(s): {unknown}. "
+            f"Available: {sorted(_MONTH_LOCALES) + ['en']}"
+        )
     for loc in locales:
         if loc == "en":
             continue
-        table = _MONTH_LOCALES.get(loc)
+        for pat, english in _MONTH_LOCALE_PATTERNS[loc]:
-        if not table:
+            s = pat.sub(english, s)
-            continue
-        for foreign, english in table.items():
-            # Word-boundary match, case-insensitive — covers ``15 janvier
-            # 2024`` and ``15. Januar 2024`` alike. The replacement also
-            # strips a trailing period after a German abbreviation (``15.``
-            # is the day; the month is the next token).
-            pattern = re.compile(
-                rf"(?<![A-Za-z]){re.escape(foreign)}(?![A-Za-z])",
-                re.IGNORECASE,
-            )
-            s = pattern.sub(english, s)
     return s
 
 
@@ -250,11 +290,7 @@ def standardize_date(
     if not s:
         return value, False
 
-    def _err(reason: str) -> tuple[str, bool]:
+    _err = lambda reason: _err_or_passthrough(reason, value, error_policy)
-        if error_policy == "sentinel":
-            sentinel = f"<error: {reason}>"
-            return sentinel, sentinel != value
-        return value, False
 
     # Excel serial dates and Unix timestamps don't survive the weekday-
     # prefix / time-tail strips, so try them first. They short-circuit
@@ -395,11 +431,7 @@ def standardize_phone(
     if not s:
         return value, False
 
-    def _err(reason: str) -> tuple[str, bool]:
+    _err = lambda reason: _err_or_passthrough(reason, value, error_policy)
-        if error_policy == "sentinel":
-            sentinel = f"<error: {reason}>"
-            return sentinel, sentinel != value
-        return value, False
 
     if output_format == "DIGITS":
         digits = re.sub(r"\D", "", s)
@@ -437,13 +469,11 @@ def standardize_phone(
     try:
         parsed = phonenumbers.parse(s, default_region)
     except phonenumbers.NumberParseException:
-        # Only emit a sentinel for inputs that clearly contain digits
+        # Anything that can't be parsed becomes a sentinel under the
-        # but failed to parse (corpus § 4.3 errors). Pure non-numeric
+        # sentinel policy; passthrough returns the original. Both digit-
-        # strings pass through unchanged so a "TBD"-style placeholder
+        # and-formatting failures and pure non-numeric ("TBD"-style) cells
-        # doesn't get reshaped into a phone error.
+        # land here.
-        if re.search(r"\d", s):
+        return _err("not a phone number")
-            return _err("not a phone number")
-        return _err("not a phone number")  # symmetric — TBD/garbage flagged
 
     if not phonenumbers.is_possible_number(parsed):
         # Distinguish "too many digits" from generic invalidity for
@@ -594,11 +624,7 @@ def standardize_currency(
     if not s:
         return value, False
 
-    def _err(reason: str) -> tuple[str, bool]:
+    _err = lambda reason: _err_or_passthrough(reason, value, error_policy)
-        if error_policy == "sentinel":
-            sentinel = f"<error: {reason}>"
-            return sentinel, sentinel != value
-        return value, False
 
     if "%" in s:
         return _err("percentage not currency")
@@ -941,51 +967,16 @@ def standardize_name(
 # Address
 # ---------------------------------------------------------------------------
 
-# Expansion table — the inverse of the dedup-side ``_USPS_ABBREVIATIONS``.
+# Expansion table — the inverse of the dedup-side compression set in
-# These are the canonical long-form spellings the standardizer emits when
+# ``normalize_address``. We deliberately don't expand ``unit``, ``loop``,
-# it sees the abbreviation. We deliberately don't expand ``unit``, ``loop``,
+# or ``way`` because those are already the long form. Canonical mappings
-# or ``way`` because those are already the long form.
+# live in :mod:`src.core._constants` so both modules stay in sync.
-_ADDRESS_EXPANSIONS: dict[str, str] = {
+from ._constants import (
-    "st": "Street",
+    USPS_EXPANSIONS as _ADDRESS_EXPANSIONS,
-    "ave": "Avenue",
+    USPS_COMPRESSIONS as _ADDRESS_COMPRESSIONS,
-    "av": "Avenue",
+    US_STATE_CODES as _US_STATE_CODES_SHARED,
-    "blvd": "Boulevard",
+    US_STATE_NAMES as _US_STATE_NAMES_SHARED,
-    "blv": "Boulevard",
+)
-    "dr": "Drive",
-    "ln": "Lane",
-    "rd": "Road",
-    "ct": "Court",
-    "pl": "Place",
-    "cir": "Circle",
-    "trl": "Trail",
-    "tr": "Trail",
-    "ter": "Terrace",
-    "pkwy": "Parkway",
-    "hwy": "Highway",
-    "expy": "Expressway",
-    "fwy": "Freeway",
-    "sq": "Square",
-    "aly": "Alley",
-    "xing": "Crossing",
-    "pt": "Point",
-    "n": "North",
-    "s": "South",
-    "e": "East",
-    "w": "West",
-    "ne": "Northeast",
-    "nw": "Northwest",
-    "se": "Southeast",
-    "sw": "Southwest",
-    "apt": "Apartment",
-    "ste": "Suite",
-    "bldg": "Building",
-    "fl": "Floor",
-    "rm": "Room",
-    "ft": "Fort",
-    "mt": "Mount",
-    "hts": "Heights",
-    "spgs": "Springs",
-}
 
 # Short tokens that look like directions but only mean a direction at the
 # start or end of an address — never in the middle of a street name. This
@@ -996,58 +987,23 @@ _DIRECTION_TOKENS = {"n", "s", "e", "w", "ne", "nw", "se", "sw"}
 
 _TOKEN_RE = re.compile(r"\w+|[^\w\s]+|\s+")
 
-# 2-letter US state postal codes — preserved verbatim so they don't get
+# Aliases over the shared constants — kept for the local module-level
-# title-cased into ``Ny``/``Ca`` and don't collide with abbreviation
+# reads that already reference these names.
-# entries (``ST`` no longer expands to ``Street`` when the surrounding
+_US_STATE_CODES = _US_STATE_CODES_SHARED
-# context says it's a state code).
+_US_STATE_NAMES = _US_STATE_NAMES_SHARED
-_US_STATE_CODES: set[str] = {
-    "AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "FL", "GA",
-    "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD",
-    "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ",
-    "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC",
-    "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY",
-    "DC", "PR", "VI", "GU", "AS", "MP",
-    # ``ST`` appears as a placeholder state in the corpus fixtures; keep
-    # it preserved so test rows don't trip the Street collision.
-    "ST",
-}
 
-# State name → 2-letter postal code. Used when ``state_to_code=True``.
+# Precompiled (pattern, code) list for the state-name → 2-letter
-_US_STATE_NAMES: dict[str, str] = {
+# conversion. Sorted longest-first so ``new york`` matches before ``new``.
-    "alabama": "AL", "alaska": "AK", "arizona": "AZ", "arkansas": "AR",
+_STATE_NAME_PATTERNS: list[tuple[re.Pattern[str], str]] = [
-    "california": "CA", "colorado": "CO", "connecticut": "CT",
+    (
-    "delaware": "DE", "florida": "FL", "georgia": "GA", "hawaii": "HI",
+        re.compile(
-    "idaho": "ID", "illinois": "IL", "indiana": "IN", "iowa": "IA",
+            rf"(,\s*){re.escape(full)}(\s+\d{{5}}(?:-\d{{4}})?)",
-    "kansas": "KS", "kentucky": "KY", "louisiana": "LA", "maine": "ME",
+            re.IGNORECASE,
-    "maryland": "MD", "massachusetts": "MA", "michigan": "MI",
+        ),
-    "minnesota": "MN", "mississippi": "MS", "missouri": "MO",
+        code,
-    "montana": "MT", "nebraska": "NE", "nevada": "NV",
+    )
-    "new hampshire": "NH", "new jersey": "NJ", "new mexico": "NM",
+    for full, code in sorted(_US_STATE_NAMES.items(), key=lambda kv: -len(kv[0]))
-    "new york": "NY", "north carolina": "NC", "north dakota": "ND",
+]
-    "ohio": "OH", "oklahoma": "OK", "oregon": "OR", "pennsylvania": "PA",
-    "rhode island": "RI", "south carolina": "SC", "south dakota": "SD",
-    "tennessee": "TN", "texas": "TX", "utah": "UT", "vermont": "VT",
-    "virginia": "VA", "washington": "WA", "west virginia": "WV",
-    "wisconsin": "WI", "wyoming": "WY",
-    "district of columbia": "DC",
-}
-
-# Inverse abbreviation table used when ``expand=False`` — compresses
-# spelled-out forms back to their USPS abbreviations.
-_ADDRESS_COMPRESSIONS: dict[str, str] = {
-    "street": "St", "avenue": "Ave", "boulevard": "Blvd",
-    "drive": "Dr", "lane": "Ln", "road": "Rd", "court": "Ct",
-    "place": "Pl", "circle": "Cir", "trail": "Trl", "terrace": "Ter",
-    "parkway": "Pkwy", "highway": "Hwy", "expressway": "Expy",
-    "freeway": "Fwy", "square": "Sq", "alley": "Aly",
-    "crossing": "Xing", "point": "Pt",
-    "north": "N", "south": "S", "east": "E", "west": "W",
-    "northeast": "NE", "northwest": "NW", "southeast": "SE",
-    "southwest": "SW",
-    "apartment": "Apt", "suite": "Ste", "building": "Bldg",
-    "floor": "Fl", "room": "Rm", "fort": "Ft", "mount": "Mt",
-    "heights": "Hts", "springs": "Spgs",
-}
 
 # PO Box variants normalize to a single canonical form.
 _PO_BOX_RE = re.compile(
@@ -1144,15 +1100,10 @@ def standardize_address(
     if state_to_code and is_us_shaped:
         # Only convert state names in the *state slot* — between a comma
         # and a US ZIP — so the city ``New York`` in ``…, New York, NY
-        # 10001`` is not shortened to ``NY``.
+        # 10001`` is not shortened to ``NY``. Patterns are precompiled
-        for full, code in sorted(
+        # at module load.
-            _US_STATE_NAMES.items(), key=lambda kv: -len(kv[0])
+        for pat, code in _STATE_NAME_PATTERNS:
-        ):
+            s = pat.sub(rf"\g<1>{code}\g<2>", s)
-            pattern = re.compile(
-                rf"(,\s*){re.escape(full)}(\s+\d{{5}}(?:-\d{{4}})?)",
-                re.IGNORECASE,
-            )
-            s = pattern.sub(rf"\g<1>{code}\g<2>", s)
 
     if not expand:
         # Compression direction is only safe for US-shaped addresses.
@@ -1297,11 +1248,7 @@ def standardize_email(
     if not s:
         return value, False
 
-    def _err(reason: str) -> tuple[str, bool]:
+    _err = lambda reason: _err_or_passthrough(reason, value, error_policy)
-        if error_policy == "sentinel":
-            sentinel = f"<error: {reason}>"
-            return sentinel, sentinel != value
-        return value, False
 
     # Multi-email cell — error before we silently pick one.
     if _EMAIL_MULTI_RE.search(s) and not s.startswith("<"):
@@ -1583,10 +1530,34 @@ class StandardizeOptions:
         known = {f for f in cls.__dataclass_fields__}
         kwargs = {k: v for k, v in data.items() if k in known}
         column_types = kwargs.get("column_types") or {}
-        kwargs["column_types"] = {
+        try:
-            c: FieldType(t) if not isinstance(t, FieldType) else t
+            kwargs["column_types"] = {
-            for c, t in column_types.items()
+                c: FieldType(t) if not isinstance(t, FieldType) else t
-        }
+                for c, t in column_types.items()
+            }
+        except ValueError as e:
+            valid = ", ".join(sorted(t.value for t in FieldType))
+            raise ValueError(
+                f"Invalid field type in column_types: {e}. Valid: {valid}"
+            ) from e
+        # Surface enum-string mismatches early — bad date_order ("xyz")
+        # would otherwise crash deep inside standardize_date.
+        for field_name, valid in (
+            ("date_order", {"MDY", "DMY"}),
+            ("phone_format", set(_PHONE_FORMAT_MAP) | {"DIGITS"}),
+            ("currency_decimal", {"dot", "comma"}),
+            ("name_case", {"title", "upper", "lower"}),
+            ("boolean_style", set(_BOOL_OUTPUT)),
+            ("date_error_policy", {"passthrough", "sentinel"}),
+            ("phone_error_policy", {"passthrough", "sentinel"}),
+            ("currency_error_policy", {"passthrough", "sentinel"}),
+            ("email_error_policy", {"passthrough", "sentinel"}),
+        ):
+            value = kwargs.get(field_name)
+            if value is not None and value not in valid:
+                raise ValueError(
+                    f"Invalid {field_name}={value!r}. Valid: {sorted(valid)}"
+                )
         return cls(**kwargs)
 
     def to_dict(self) -> dict:
@@ -1602,7 +1573,20 @@ class StandardizeOptions:
 
     @classmethod
     def from_file(cls, path: str | Path) -> StandardizeOptions:
-        return cls.from_dict(json.loads(Path(path).read_text()))
+        path = Path(path)
+        try:
+            text = path.read_text()
+        except OSError as e:
+            raise OSError(
+                f"Could not read StandardizeOptions config from {path}: {e}"
+            ) from e
+        try:
+            data = json.loads(text)
+        except json.JSONDecodeError as e:
+            raise ValueError(
+                f"Invalid JSON in StandardizeOptions config {path}: {e}"
+            ) from e
+        return cls.from_dict(data)
 
 
 @dataclass
@@ -1826,6 +1810,20 @@ def standardize_dataframe(
         columns=["row", "column", "field_type", "old", "new"],
     )
 
+    # Surface a warning when more than 10% of typed cells failed to
+    # parse — usually means the user mis-typed a column (text marked
+    # as DATE) or the data is genuinely garbage. Without this, a
+    # quietly-broken pipeline shows zero changes and silently lets bad
+    # data flow downstream.
+    if cells_total > 0 and cells_unparseable / cells_total > 0.1:
+        logger.warning(
+            "standardize_dataframe: {}/{} cells ({}%) in typed columns were "
+            "unparseable — check column_types for mismatches with the data.",
+            cells_unparseable,
+            cells_total,
+            int(100 * cells_unparseable / cells_total),
+        )
+
     return StandardizeResult(
         standardized_df=out,
         changes=changes_df,

src/core/io.py

@@ -184,9 +184,18 @@ def read_file(
     """
     filepath = Path(path)
     if not filepath.exists():
-        raise FileNotFoundError(f"File not found: {filepath}")
+        raise FileNotFoundError(
+            f"Input file not found: {filepath} "
+            f"(required for encoding/delimiter detection and reading)"
+        )
+    if chunk_size is not None and chunk_size <= 0:
+        raise ValueError(f"chunk_size must be positive; got {chunk_size}")
 
     suffix = filepath.suffix.lower()
+    logger.info(
+        "read_file: {} (suffix={}, chunk_size={})",
+        filepath, suffix, chunk_size,
+    )
     if suffix in (".xlsx", ".xls"):
         return _read_excel(filepath, header_row=header_row, sheet_name=sheet_name)
     else:
@@ -362,6 +371,10 @@ def write_file(
 
     Returns the resolved output Path.
     """
+    if not isinstance(df, pd.DataFrame):
+        raise TypeError(
+            f"write_file() requires a pandas DataFrame; got {type(df).__name__}"
+        )
     out = Path(path)
     fmt = file_format or out.suffix.lstrip(".").lower()
     if fmt in ("xlsx", "xls"):

src/core/normalizers.py

@@ -151,70 +151,22 @@ def normalize_name(value: Optional[str]) -> str:
 # Address normalizer
 # ---------------------------------------------------------------------------
 
+# Long-form → short-form (USPS) for normalization-side matching keys.
+# Sourced from the shared canonical map; lower-cased + augmented with a
+# few normalize-only aliases (``saint`` → ``st``, identity entries for
+# ``unit`` / ``loop`` / ``way``, ``number`` → ``#``).
+from ._constants import USPS_COMPRESSIONS as _SHARED_COMPRESSIONS, US_STATE_NAMES as _SHARED_STATE_NAMES
+
 _USPS_ABBREVIATIONS: dict[str, str] = {
-    "street": "st",
+    **{k: v.lower() for k, v in _SHARED_COMPRESSIONS.items()},
-    "avenue": "ave",
+    "way": "way", "loop": "loop", "unit": "unit",
-    "boulevard": "blvd",
-    "drive": "dr",
-    "lane": "ln",
-    "road": "rd",
-    "court": "ct",
-    "place": "pl",
-    "circle": "cir",
-    "trail": "trl",
-    "way": "way",
-    "terrace": "ter",
-    "parkway": "pkwy",
-    "highway": "hwy",
-    "expressway": "expy",
-    "freeway": "fwy",
-    "square": "sq",
-    "loop": "loop",
-    "alley": "aly",
-    "crossing": "xing",
-    "point": "pt",
-    "north": "n",
-    "south": "s",
-    "east": "e",
-    "west": "w",
-    "northeast": "ne",
-    "northwest": "nw",
-    "southeast": "se",
-    "southwest": "sw",
-    "apartment": "apt",
-    "suite": "ste",
-    "building": "bldg",
-    "floor": "fl",
-    "room": "rm",
-    "unit": "unit",
     "number": "#",
     "saint": "st",
-    "fort": "ft",
-    "mount": "mt",
-    "heights": "hts",
-    "springs": "spgs",
 }
 
-
+# Lowercase variant of the shared state-name map for matching keys.
-# US state name → 2-letter postal code. Substituted before tokenization
-# so ``California`` and ``CA`` normalize to the same key.
 _US_STATE_NAMES_NORM: dict[str, str] = {
-    "alabama": "al", "alaska": "ak", "arizona": "az", "arkansas": "ar",
+    name: code.lower() for name, code in _SHARED_STATE_NAMES.items()
-    "california": "ca", "colorado": "co", "connecticut": "ct",
-    "delaware": "de", "florida": "fl", "georgia": "ga", "hawaii": "hi",
-    "idaho": "id", "illinois": "il", "indiana": "in", "iowa": "ia",
-    "kansas": "ks", "kentucky": "ky", "louisiana": "la", "maine": "me",
-    "maryland": "md", "massachusetts": "ma", "michigan": "mi",
-    "minnesota": "mn", "mississippi": "ms", "missouri": "mo",
-    "montana": "mt", "nebraska": "ne", "nevada": "nv",
-    "new hampshire": "nh", "new jersey": "nj", "new mexico": "nm",
-    "new york": "ny", "north carolina": "nc", "north dakota": "nd",
-    "ohio": "oh", "oklahoma": "ok", "oregon": "or", "pennsylvania": "pa",
-    "rhode island": "ri", "south carolina": "sc", "south dakota": "sd",
-    "tennessee": "tn", "texas": "tx", "utah": "ut", "vermont": "vt",
-    "virginia": "va", "washington": "wa", "west virginia": "wv",
-    "wisconsin": "wi", "wyoming": "wy",
-    "district of columbia": "dc",
 }
 
 

src/core/text_clean.py

@@ -18,6 +18,7 @@ from pathlib import Path
 from typing import Any, Callable, Iterable, Literal, Optional
 
 import pandas as pd
+from loguru import logger
 from pandas.api import types as pdtypes
 
 
@@ -535,7 +536,16 @@ def clean_dataframe(df: pd.DataFrame, options: Optional[CleanOptions] = None) ->
     Numeric, datetime, and boolean columns are skipped by default. The input
     DataFrame is not mutated; a copy is returned in ``CleanResult.cleaned_df``.
     """
+    if not isinstance(df, pd.DataFrame):
+        raise TypeError(
+            f"clean_dataframe() requires a pandas DataFrame; "
+            f"got {type(df).__name__}"
+        )
     options = options or CleanOptions()
+    logger.debug(
+        "clean_dataframe: rows={}, cols={}, case={}",
+        len(df), len(df.columns), options.case,
+    )
     out = df.copy()
     columns = _select_columns(out, options)
 

tests/test_audit_fixes.py

@@ -301,3 +301,76 @@ class TestNullLikeIncludesPandasNA:
         # keep_default_na=False, pandas NA values appear as the literal
         # string "<NA>" and the analyzer should flag them.
         assert "<na>" in _NULL_LIKE
+
+
+# ---------------------------------------------------------------------------
+# Production-readiness review (refactor pass)
+# ---------------------------------------------------------------------------
+
+class TestProductionReadyValidation:
+    def test_chunk_size_must_be_positive(self, tmp_path: Path):
+        from src.core.io import read_file
+        f = tmp_path / "tiny.csv"
+        f.write_text("a,b\n1,2\n")
+        with pytest.raises(ValueError, match="chunk_size must be positive"):
+            list(read_file(f, chunk_size=0))
+        with pytest.raises(ValueError, match="chunk_size must be positive"):
+            list(read_file(f, chunk_size=-5))
+
+    def test_write_file_rejects_non_dataframe(self, tmp_path: Path):
+        from src.core.io import write_file
+        with pytest.raises(TypeError, match="requires a pandas DataFrame"):
+            write_file({"a": [1]}, tmp_path / "out.csv")  # type: ignore[arg-type]
+
+    def test_clean_dataframe_rejects_non_dataframe(self):
+        from src.core.text_clean import clean_dataframe
+        with pytest.raises(TypeError, match="requires a pandas DataFrame"):
+            clean_dataframe([{"a": 1}])  # type: ignore[arg-type]
+
+    def test_deduplicate_rejects_non_dataframe(self):
+        from src.core.dedup import deduplicate
+        with pytest.raises(TypeError, match="requires a pandas DataFrame"):
+            deduplicate({"x": [1]})  # type: ignore[arg-type]
+
+    def test_keep_most_recent_requires_date_column(self):
+        from src.core.dedup import deduplicate, SurvivorRule
+        df = pd.DataFrame({"name": ["a", "b"]})
+        with pytest.raises(ValueError, match="date_column"):
+            deduplicate(df, survivor_rule=SurvivorRule.KEEP_MOST_RECENT)
+
+    def test_keep_most_recent_with_unknown_date_column(self):
+        from src.core.dedup import deduplicate, SurvivorRule
+        df = pd.DataFrame({"name": ["a", "b"]})
+        with pytest.raises(ValueError, match="not found in input"):
+            deduplicate(
+                df,
+                survivor_rule=SurvivorRule.KEEP_MOST_RECENT,
+                date_column="created_at",
+            )
+
+    def test_standardize_options_invalid_enum(self):
+        from src.core.format_standardize import StandardizeOptions
+        with pytest.raises(ValueError, match="Invalid date_order"):
+            StandardizeOptions.from_dict({"date_order": "XYZ"})
+
+    def test_standardize_options_invalid_field_type(self):
+        from src.core.format_standardize import StandardizeOptions
+        with pytest.raises(ValueError, match="Invalid field type"):
+            StandardizeOptions.from_dict({"column_types": {"x": "made_up"}})
+
+    def test_month_locale_validation(self):
+        from src.core.format_standardize import standardize_date
+        with pytest.raises(ValueError, match="Unknown month locale"):
+            standardize_date("15 januar 2024", month_locales=["DE"])  # uppercase typo
+
+    def test_config_from_file_missing(self, tmp_path: Path):
+        from src.core.config import DeduplicationConfig
+        with pytest.raises(OSError, match="Could not read"):
+            DeduplicationConfig.from_file(tmp_path / "missing.json")
+
+    def test_config_from_file_bad_json(self, tmp_path: Path):
+        from src.core.config import DeduplicationConfig
+        path = tmp_path / "bad.json"
+        path.write_text("{not: valid json")
+        with pytest.raises(ValueError, match="Invalid JSON"):
+            DeduplicationConfig.from_file(path)