correct: Poll the deadline inside structural traversals

src/codex32/indel.py

@@ -159,15 +159,23 @@ def _alignment_counts(
     return counts
 
 
-def _views(text: str, target: int, shape: _StructuralClass, immutable: int, base: int) -> Iterator[_View]:
+def _views(
+    text: str, target: int, shape: _StructuralClass, immutable: int, base: int, deadline: float | None = None
+) -> Iterator[_View]:
+    # Skipped repeated-symbol scripts can run for minutes between yields; poll here.
+    def expired() -> bool:
+        return deadline is not None and monotonic() >= deadline
+
     source = tuple(CHARSET.find(char.lower()) for char in text[base:])
     initial = _View(source, ((0, len(source)),), len(source))
     boundary = (immutable if shape.unit == 1 else _group_boundary(immutable)) - base
     width = shape.unit
     if not (shape.adjacent or shape.distant or shape.corrupted):
         observed_units = (len(source) - boundary) // width
         target_units = (target - base - boundary) // width
-        for deleted in combinations(range(observed_units), shape.inserted):
+        for number, deleted in enumerate(combinations(range(observed_units), shape.inserted)):
+            if number % 1024 == 0 and expired():
+                return
             # Canonical deletion within a run of equal units; no retained-body allocation.
             if any(
                 i
@@ -197,6 +205,8 @@ def walk(view: _View, operations: tuple[str, ...]) -> Iterator[_View]:
             rest = operations[:index] + operations[index + 1 :]
             if operation in ("I", "O", "GS"):
                 for unit in range(units + (operation == "O")):
+                    if expired():
+                        return
                     position = boundary + width * unit
                     yield from walk(
                         view.mask(position, width)
@@ -212,6 +222,8 @@ def walk(view: _View, operations: tuple[str, ...]) -> Iterator[_View]:
                         range(left + 1, min(left + 2, units)) if operation == "AT" else range(left + 2, units)
                     )
                     for right in rights:
+                        if expired():
+                            return
                         p, q = boundary + width * left, boundary + width * right
                         if all(view[p + i] == view[q + i] for i in range(width)):
                             continue
@@ -489,7 +501,9 @@ def _search_target(
         if incremental is None:
             incremental = _IncrementalSyndromes(solver.alignment, source)
         alignments = (
-            _views(text, state.target, shape, state.immutable, state.base) if views is None else views
+            _views(text, state.target, shape, state.immutable, state.base, deadline)
+            if views is None
+            else views
         )
         for number, view in enumerate(alignments):
             if number % 32 == 0 and deadline is not None and monotonic() >= deadline:
@@ -544,7 +558,7 @@ def _search_target(
                 candidate = replace(candidate, edits=candidate.edits + tuple(moved))
             if candidate.capture_volume == frontier[key]:
                 _keep(results, candidate)
-    return True
+    return deadline is None or monotonic() < deadline
 
 
 def _search_many(

tests/test_competitors.py

@@ -40,10 +40,10 @@ def test_reported_substitutions_exhaust_competitors_without_redundant_enumeratio
     original = indel._views
     searched = []
 
-    def views(text, target, shape, immutable, base):
+    def views(text, target, shape, immutable, base, deadline):
         searched.append((target, shape.operations, shape.unit))
         assert not (shape.unit == 1 and (shape.adjacent or shape.distant))
-        yield from original(text, target, shape, immutable, base)
+        yield from original(text, target, shape, immutable, base, deadline)
 
     with patch.object(indel, "_views", side_effect=views):
         candidates, complete = _run(REPORTED)

tests/test_correction_indel.py

@@ -1,7 +1,7 @@
 """Structural-family, immutable-prefix, ranking, and completion evidence."""
 
 from dataclasses import replace
-from itertools import combinations
+from itertools import combinations, count
 from math import comb
 from unittest.mock import patch
 
@@ -26,6 +26,8 @@
     _required_header_substitutions,
     _search_many,
     _search_target,
+    _StructuralClass,
+    _views,
 )
 from codex32.profiles.ms32 import TEXT_LENGTHS
 from tools._wallet_test_vectors import FIXTURE_SEED, core_fingerprint
@@ -557,6 +559,30 @@ def test_structural_input_and_deadline_are_bounded() -> None:
     assert candidates == () and not complete
 
 
+@pytest.mark.parametrize(
+    "shape", [_StructuralClass(3, 0, adjacent=1), _StructuralClass(4, 0), _StructuralClass(0, 0, distant=1)]
+)
+def test_structural_views_poll_the_deadline_between_yields(shape: _StructuralClass) -> None:
+    # Edits within one repeated-symbol run are skipped as duplicates, so these
+    # traversals can run long without yielding; one clock tick per poll.
+    text = "ms10tests" + "q" * 117
+    clock = count()
+    with patch("codex32.indel.monotonic", side_effect=lambda: next(clock)):
+        assert len(tuple(_views(text, len(text) - shape.delta, shape, 9, 3, deadline=100))) <= 1
+    assert 100 < next(clock) < 200
+
+
+def test_expired_final_traversal_reports_an_incomplete_search() -> None:
+    text = "ms10tests" + "q" * 122
+    state = _prepare(CorrectionContext(Profile.MS, 127), text, _CLASSES, None)
+    assert state is not None
+    shape = _StructuralClass(4, 0)
+    key = next(key for key in _frontier((state,), frozenset((127,))) if key[1] == shape)
+    clock = count()
+    with patch("codex32.indel.monotonic", side_effect=lambda: next(clock)):
+        assert not _search_target(replace(state, counts={shape: state.counts[shape]}), {key: 1}, {}, 5)
+
+
 def test_full_checksum_burst_is_admitted_at_the_shared_mass_ceiling():
     from codex32.correction import _correct_fixed