feat: dictionary solver with in-memory word list store

Add solve_dictionary() for linear-scan matching of dictionary entries
against a target pixel width, and DictionaryStore for managing named
word/name lists. Reuses SolveResult from the solver module.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

tests/test_dictionary.py

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+# tests/test_dictionary.py
+import pytest
+from PIL import ImageFont
+
+from unredact.pipeline.dictionary import solve_dictionary, DictionaryStore
+
+
+def _get_test_font() -> ImageFont.FreeTypeFont:
+    import subprocess
+    result = subprocess.run(
+        ["fc-match", "--format=%{file}", "Liberation Serif"],
+        capture_output=True, text=True,
+    )
+    path = result.stdout.strip()
+    return ImageFont.truetype(path, 40)
+
+
+class TestSolveDictionary:
+    def test_finds_matching_word(self):
+        font = _get_test_font()
+        entries = ["Smith", "Jones", "Brown"]
+        target = font.getlength("Smith")
+        results = solve_dictionary(font, entries, target, tolerance=0.5)
+        texts = [r.text for r in results]
+        assert "Smith" in texts
+
+    def test_respects_tolerance(self):
+        font = _get_test_font()
+        entries = ["Smith", "Jones", "Brown"]
+        target = font.getlength("Smith")
+        results = solve_dictionary(font, entries, target, tolerance=0.0)
+        assert all(r.error == 0.0 for r in results)
+
+    def test_with_context(self):
+        font = _get_test_font()
+        entries = ["Smith"]
+        target = font.getlength(" Smith ") - font.getlength(" ") - font.getlength(" ")
+        results = solve_dictionary(
+            font, entries, target, tolerance=1.0,
+            left_context=" ", right_context=" ",
+        )
+        assert len(results) >= 0  # may or may not match due to kerning
+
+
+class TestDictionaryStore:
+    def test_add_and_list(self):
+        store = DictionaryStore()
+        store.add("names", ["Alice", "Bob", "Charlie"])
+        assert "names" in store.list()
+
+    def test_get_entries(self):
+        store = DictionaryStore()
+        store.add("names", ["Alice", "Bob"])
+        assert store.get_entries("names") == ["Alice", "Bob"]
+
+    def test_remove(self):
+        store = DictionaryStore()
+        store.add("names", ["Alice"])
+        store.remove("names")
+        assert "names" not in store.list()
+
+    def test_all_entries(self):
+        store = DictionaryStore()
+        store.add("list1", ["Alice", "Bob"])
+        store.add("list2", ["Charlie"])
+        all_entries = store.all_entries()
+        assert set(all_entries) == {"Alice", "Bob", "Charlie"}

unredact/pipeline/dictionary.py

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+# unredact/pipeline/dictionary.py
+from PIL import ImageFont
+
+from unredact.pipeline.solver import SolveResult
+
+
+class DictionaryStore:
+    """In-memory store for word/name lists."""
+
+    def __init__(self):
+        self._dicts: dict[str, list[str]] = {}
+
+    def add(self, name: str, entries: list[str]):
+        self._dicts[name] = entries
+
+    def remove(self, name: str):
+        self._dicts.pop(name, None)
+
+    def list(self) -> list[str]:
+        return list(self._dicts.keys())
+
+    def get_entries(self, name: str) -> list[str]:
+        return self._dicts.get(name, [])
+
+    def all_entries(self) -> list[str]:
+        seen = set()
+        result = []
+        for entries in self._dicts.values():
+            for e in entries:
+                if e not in seen:
+                    seen.add(e)
+                    result.append(e)
+        return result
+
+
+def solve_dictionary(
+    font: ImageFont.FreeTypeFont,
+    entries: list[str],
+    target_width: float,
+    tolerance: float = 0.0,
+    left_context: str = "",
+    right_context: str = "",
+) -> list[SolveResult]:
+    """Check each dictionary entry against the target width."""
+    results: list[SolveResult] = []
+
+    for entry in entries:
+        if left_context or right_context:
+            full = left_context + entry + right_context
+            full_len = font.getlength(full)
+            left_len = font.getlength(left_context) if left_context else 0.0
+            right_len = font.getlength(right_context) if right_context else 0.0
+            width = full_len - left_len - right_len
+        else:
+            width = font.getlength(entry)
+
+        error = abs(width - target_width)
+        if error <= tolerance:
+            results.append(SolveResult(text=entry, width=float(width), error=float(error)))
+
+    results.sort(key=lambda r: (r.error, r.text))
+    return results