Move correction references out of runtime

Keep test and benchmark-only structural helpers under tools/ so they no longer count against the installed review surface. Runtime search behavior is unchanged.\n\nValidation: Ruff, format check, mypy, focused correction tests, and the production-size budget test pass.

Author: Codex Preflight

src/codex32/indel.py

@@ -88,8 +88,6 @@ def _classes(unit: int, depth: int) -> tuple[_StructuralClass, ...]:
 _CHARACTER_CLASSES = _classes(1, 4)
 _GROUP_CLASSES = _classes(4, 2)
 _CLASSES = (_FIXED, *_CHARACTER_CLASSES, *_GROUP_CLASSES)
-# Compatibility for older offline tools; public search uses the full class set.
-_REDUCED_CLASSES = tuple(shape for shape in _CLASSES if shape.unit == 4 or shape.distance <= 3)
 
 
 def _group_boundary(immutable_length: int) -> int:
@@ -161,44 +159,6 @@ def _alignment_counts(
     return counts
 
 
-def _alignment_count(
-    shape: _StructuralClass,
-    observed_length: int,
-    target_length: int,
-    immutable_length: int,
-) -> int:
-    return sum(_alignment_counts(shape, "q" * observed_length, target_length, immutable_length).values())
-
-
-def _reductions(
-    values: tuple[int, ...],
-    characters: str,
-    count: int,
-    offset: int,
-) -> Iterator[tuple[tuple[int, ...], tuple[tuple[int, str], ...]]]:
-    for deleted in combinations(range(len(values)), count):
-        removed = frozenset(deleted)
-        kept = tuple(index for index in range(len(values)) if index not in removed)
-        retained = tuple(values[index] for index in kept)
-        position = 0
-        for kept_index in kept:
-            while values[position] != values[kept_index]:
-                position += 1
-            if position != kept_index:
-                break
-            position += 1
-        else:
-            edits = tuple((offset + index, characters[index]) for index in deleted)
-            yield retained, edits
-
-
-def _variants(
-    text: str, target: int, shape: _StructuralClass, immutable: int, prefix_length: int = 3
-) -> Iterator[_Variant]:
-    for view in _views(text, target, shape, immutable, prefix_length):
-        yield _view_variant(view, text, prefix_length)
-
-
 def _views(text: str, target: int, shape: _StructuralClass, immutable: int, base: int) -> Iterator[_View]:
     source = tuple(CHARSET.find(char.lower()) for char in text[base:])
     initial = _View(source, ((0, len(source)),), len(source))

tests/test_correction_indel.py

@@ -19,21 +19,19 @@
     _CLASSES,
     _FIXED,
     _GROUP_CLASSES,
-    _REDUCED_CLASSES,
-    _alignment_count,
     _alignment_counts,
     _capacities,
     _frontier,
     _keep,
     _prepare,
-    _reductions,
     _required_header_substitutions,
     _search_many,
     _search_target,
 )
 from codex32.profiles.ms32 import TEXT_LENGTHS
 from tools._wallet_reference import fingerprint_seed
 from tools.correction_capture import cross_length_classes
+from tools.correction_reference import _REDUCED_CLASSES, _alignment_count, _reductions
 
 SOURCE = VECTOR_1["secret_s"]
 CONTEXT = CorrectionContext(Profile.MS, expected_length=len(SOURCE))

tools/correction_benchmark.py

@@ -15,13 +15,12 @@
 from codex32.correction import CorrectionContext
 from codex32.indel import (
     _CHARACTER_CLASSES,
-    _alignment_count,
     _required_header_substitutions,
     _search_many,
-    _variants,
 )
 from codex32.profiles import Profile
 from codex32.profiles.ms32 import TEXT_LENGTHS
+from tools.correction_reference import _alignment_count, _variants
 
 DELTAS = (-8, -4, -3, -2, -1, 0, 1, 2, 3, 4, 8)
 AUTOMATIC_48_COUNTS = (40, *range(44, 53), 56)

tools/correction_reference.py

@@ -0,0 +1,53 @@
+"""Reference-only structural helpers used by tests and correction benchmarks."""
+
+from collections.abc import Iterator
+from itertools import combinations
+
+from codex32.indel import (
+    _CLASSES,
+    _alignment_counts,
+    _StructuralClass,
+    _Variant,
+    _view_variant,
+    _views,
+)
+
+_REDUCED_CLASSES = tuple(shape for shape in _CLASSES if shape.unit == 4 or shape.distance <= 3)
+
+
+def _alignment_count(
+    shape: _StructuralClass,
+    observed_length: int,
+    target_length: int,
+    immutable_length: int,
+) -> int:
+    return sum(_alignment_counts(shape, "q" * observed_length, target_length, immutable_length).values())
+
+
+def _reductions(
+    values: tuple[int, ...],
+    characters: str,
+    count: int,
+    offset: int,
+) -> Iterator[tuple[tuple[int, ...], tuple[tuple[int, str], ...]]]:
+    for deleted in combinations(range(len(values)), count):
+        removed = frozenset(deleted)
+        kept = tuple(index for index in range(len(values)) if index not in removed)
+        retained = tuple(values[index] for index in kept)
+        position = 0
+        for kept_index in kept:
+            while values[position] != values[kept_index]:
+                position += 1
+            if position != kept_index:
+                break
+            position += 1
+        else:
+            edits = tuple((offset + index, characters[index]) for index in deleted)
+            yield retained, edits
+
+
+def _variants(
+    text: str, target: int, shape: _StructuralClass, immutable: int, prefix_length: int = 3
+) -> Iterator[_Variant]:
+    for view in _views(text, target, shape, immutable, prefix_length):
+        yield _view_variant(view, text, prefix_length)