fix(compact): time-stamp the Memory Compact heading (#768)

src/memsearch/core.py

@@ -5,7 +5,7 @@
 import asyncio
 import logging
 from collections.abc import Callable, Iterator
-from datetime import date
+from datetime import datetime
 from pathlib import Path
 from typing import TYPE_CHECKING, Any
 
@@ -331,11 +331,14 @@ async def compact(
         base = Path(output_dir) if output_dir else Path(self._paths[0]) if self._paths else Path.cwd()
         memory_dir = base / "memory"
         memory_dir.mkdir(parents=True, exist_ok=True)
-        compact_file = memory_dir / f"{date.today()}.md"
-        compact_heading = "\n\n## Memory Compact\n\n"
+        # Time-stamp the heading (like the plugins' ``## Session HH:MM``) so two
+        # compactions on the same day stay distinguishable in the daily file.
+        now = datetime.now()
+        compact_file = memory_dir / f"{now.date()}.md"
+        compact_heading = f"\n\n## Memory Compact {now:%H:%M}\n\n"
         with open(compact_file, "a", encoding="utf-8") as f:
             if compact_file.stat().st_size == 0:
-                f.write(f"# {date.today()}\n")
+                f.write(f"# {now.date()}\n")
             f.write(compact_heading)
             f.write(summary)
             f.write("\n")

tests/test_compact_heading_time.py

@@ -0,0 +1,68 @@
+"""`compact` must time-stamp its heading so same-day compactions can be told apart (#768).
+
+Before the fix every compaction wrote the fixed heading ``## Memory Compact``, so two
+compactions on the same day left two identical headings in the daily file.
+"""
+
+from __future__ import annotations
+
+import re
+from datetime import datetime
+from pathlib import Path
+from typing import Any
+
+import pytest
+
+from memsearch.core import MemSearch
+
+
+class FakeStore:
+    def query(self, filter_expr: str = "", **_: Any) -> list[dict[str, Any]]:
+        return [{"content": "a stored chunk"}]
+
+
+def make_memsearch(monkeypatch: pytest.MonkeyPatch, tmp_path: Path, clock: list[datetime]) -> MemSearch:
+    """A MemSearch with no Milvus and no LLM; ``datetime.now()`` pops from *clock*."""
+    monkeypatch.chdir(tmp_path)
+    ms = MemSearch.__new__(MemSearch)
+    ms._paths = [str(tmp_path)]
+    ms._store = FakeStore()
+
+    async def fake_compact_chunks(*_args: Any, **_kwargs: Any) -> str:
+        return "- a summary line"
+
+    async def fake_index_file(_path: str | Path) -> int:
+        return 1
+
+    class FakeDatetime:
+        @staticmethod
+        def now() -> datetime:
+            return clock.pop(0)
+
+    monkeypatch.setattr("memsearch.core.compact_chunks", fake_compact_chunks)
+    monkeypatch.setattr("memsearch.core.datetime", FakeDatetime)
+    monkeypatch.setattr(ms, "index_file", fake_index_file)
+    return ms
+
+
+async def test_same_day_compactions_get_distinct_time_headings(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
+    clock = [datetime(2026, 10, 13, 14, 30), datetime(2026, 10, 13, 16, 5)]
+    ms = make_memsearch(monkeypatch, tmp_path, clock)
+
+    await ms.compact()
+    await ms.compact()
+
+    text = (tmp_path / "memory" / "2026-10-13.md").read_text(encoding="utf-8")
+    headings = re.findall(r"^## Memory Compact.*$", text, flags=re.MULTILINE)
+    assert headings == ["## Memory Compact 14:30", "## Memory Compact 16:05"]
+    assert text.startswith("# 2026-10-13\n")
+
+
+async def test_heading_keeps_the_memory_compact_prefix(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
+    """Readers that match the old ``## Memory Compact`` prefix keep working."""
+    ms = make_memsearch(monkeypatch, tmp_path, [datetime(2026, 1, 2, 3, 4)])
+
+    await ms.compact()
+
+    text = (tmp_path / "memory" / "2026-01-02.md").read_text(encoding="utf-8")
+    assert "\n\n## Memory Compact 03:04\n\n- a summary line\n" in text