feat: mdgrep 0.1.0 – boolean full-text search for Markdown

- query language: substrings, phrases, /regex/, AND/OR/NOT (+ UND/ODER/NICHT),
  parentheses; case-insensitive; ReDoS protection via regex timeouts;
  syntax errors with stable code and position
- SearchEngine over in-memory blocks: filters, predicate, grouping, sorting,
  paging, time budget, automatic reload, highlighted snippets
- Markdown loader with split modes file/heading/list/paragraph
- grep-like CLI (mdgrep), JSON output, grep exit codes
- Flask blueprint/app with JSON API and widget assets, dev server
- framework-free JS widget: live search, URL state, filters, paging,
  syntax help, en/de labels, CSS custom properties for theming

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

tests/test_engine.py

@@ -0,0 +1,116 @@
+import pytest
+
+from mdgrep import Block, QuerySyntaxError, SearchEngine
+
+
+def blk(i, text, **meta):
+    return Block(id=str(i), text=text, title=f"T{i} {text.split()[0]}", meta=meta)
+
+
+BLOCKS = [
+    blk(1, "rust compiler news", lang="en", date="2026-01-01", url="u1"),
+    blk(2, "rust compiler news again", lang="en", date="2026-02-01", url="u1"),
+    blk(3, "Rust Übersetzer", lang="de", date="2026-01-15", url="u1"),
+    blk(4, "go generics", lang="en", date="2026-03-01", url="u2"),
+    blk(5, "python typing and rust bindings", lang="en", date="2025-12-01", url="u3"),
+]
+
+
+def ids(result):
+    return [g.block.id for g in result.groups]
+
+
+def test_basic_search_original_order():
+    res = SearchEngine(BLOCKS).search("rust")
+    assert ids(res) == ["1", "2", "3", "5"]
+    assert res.total_blocks == 4 and res.total_groups == 4
+
+
+def test_filters_single_and_multiple_values():
+    eng = SearchEngine(BLOCKS)
+    assert ids(eng.search("rust", filters={"lang": "de"})) == ["3"]
+    assert ids(eng.search("rust", filters={"lang": ["de", "en"]})) == ["1", "2", "3", "5"]
+    assert ids(eng.search("rust", filters={"lang": ""})) == ["1", "2", "3", "5"]
+
+
+def test_predicate():
+    res = SearchEngine(BLOCKS).search("rust", predicate=lambda b: b.id != "1")
+    assert ids(res) == ["2", "3", "5"]
+
+
+def test_sort_newest_first():
+    res = SearchEngine(BLOCKS).search("rust", sort_key=lambda b: b.meta["date"], reverse=True)
+    assert ids(res) == ["2", "3", "1", "5"]
+
+
+def test_grouping_uses_first_block_after_sorting():
+    res = SearchEngine(BLOCKS).search(
+        "rust", sort_key=lambda b: b.meta["date"], reverse=True,
+        group_by=lambda b: (b.meta["lang"], b.meta["url"]))
+    assert ids(res) == ["2", "3", "5"]
+    assert [b.id for b in res.groups[0].also] == ["1"]
+    assert res.total_groups == 3 and res.total_blocks == 4
+
+
+def test_title_is_searched():
+    eng = SearchEngine([Block("t", "body text", title="Special Title")])
+    res = eng.search("special")
+    assert ids(res) == ["t"]
+    assert res.groups[0].title_segments == [{"t": "Special", "hit": True}, {"t": " Title", "hit": False}]
+    assert res.groups[0].hits == 0     # hits counts snippet matches
+
+
+def test_paging():
+    eng = SearchEngine(BLOCKS)
+    first = eng.search("rust", limit=2)
+    assert ids(first) == ["1", "2"] and first.next_offset == 2
+    second = eng.search("rust", limit=2, offset=first.next_offset)
+    assert ids(second) == ["3", "5"] and second.next_offset is None
+
+
+def test_segments_and_title_segments():
+    res = SearchEngine(BLOCKS).search("compiler")
+    d = res.to_dict()["results"][0]["block"]
+    assert {"t": "compiler", "hit": True} in d["segments"]
+    assert d["hits"] == 1
+    assert d["title_segments"] == [{"t": "T1 rust", "hit": False}]
+
+
+def test_to_dict_contract():
+    d = SearchEngine(BLOCKS).search("go", limit=10).to_dict()
+    assert set(d) == {"query", "total_groups", "total_blocks", "offset", "limit",
+                      "next_offset", "truncated", "elapsed_ms", "results"}
+    r = d["results"][0]
+    assert set(r) == {"block", "also"}
+    assert r["block"]["meta"] == {"lang": "en", "date": "2026-03-01", "url": "u2"}
+
+
+def test_syntax_error_propagates():
+    with pytest.raises(QuerySyntaxError):
+        SearchEngine(BLOCKS).search("(rust")
+
+
+def test_time_budget_truncates():
+    blocks = [Block(id=str(i), text="a" * 30 + "!") for i in range(50)]
+    res = SearchEngine(blocks).search("/(a|aa)+$/", time_budget=0.3)
+    assert res.truncated
+    assert res.elapsed_ms < 3000
+
+
+def test_reload_on_token_change():
+    state = {"token": 1, "blocks": [Block("a", "first")]}
+    eng = SearchEngine(lambda: list(state["blocks"]), reload_check=lambda: state["token"],
+                       reload_interval=0)
+    assert ids(eng.search("first")) == ["a"]
+    state["blocks"] = [Block("b", "second")]
+    assert ids(eng.search("second")) == []          # token unchanged → no reload
+    state["token"] = 2
+    assert ids(eng.search("second")) == ["b"]
+
+
+def test_reload_interval_respected():
+    calls = []
+    eng = SearchEngine(lambda: [], reload_check=lambda: calls.append(1) or 1, reload_interval=3600)
+    eng.search("x")
+    eng.search("x")
+    assert len(calls) == 1     # only the initial check