diff --git a/src/projectmem/commands/auto_capture.py b/src/projectmem/commands/auto_capture.py
index 8f3a55a..86851ba 100644
--- a/src/projectmem/commands/auto_capture.py
+++ b/src/projectmem/commands/auto_capture.py
@@ -134,6 +134,10 @@ def _capture_commit(root: Path) -> None:
         return
 
     files = _git_last_changed_files(root)
+    # The location is the code this commit is about. Memory files are skipped:
+    # summary.md is regenerated on every event, so it is in most commits, and
+    # `.projectmem/` sorts ahead of most paths — `files[0]` was usually it (#20).
+    code_files = [f for f in files if not f.startswith(f"{MEM_DIR}/")]
     commit_hash = get_git_commit(root)
 
     # Deduplicate: don't re-log if this commit is already captured
@@ -166,7 +170,7 @@ def _capture_commit(root: Path) -> None:
         outcome=matched["outcome"],
         files=files[:10],  # Cap at 10 files
         git_commit=commit_hash,
-        location=files[0] if files else None,
+        location=code_files[0] if code_files else None,
         auto_captured=True,
         capture_source=matched["capture_source"],
         capture_confidence=matched["confidence"],
diff --git a/tests/test_auto_capture.py b/tests/test_auto_capture.py
new file mode 100644
index 0000000..86bc220
--- /dev/null
+++ b/tests/test_auto_capture.py
@@ -0,0 +1,69 @@
+"""Auto-capture must tag a commit with the code it touched, not with memory.
+
+#20: `location` was `files[0]`. git lists changed paths sorted, `.projectmem/`
+sorts ahead of most paths because of the leading dot, and summary.md is
+regenerated on every event — so most commits were located at
+`.projectmem/summary.md`. The staleness check then counted every later commit
+to summary.md against them and flagged nearly all as possibly stale.
+"""
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+from projectmem.commands.auto_capture import _capture_commit
+from projectmem.storage import initialize, read_events
+
+
+def _git(root: Path, *args: str) -> None:
+    subprocess.run(["git", *args], cwd=root, check=True, capture_output=True)
+
+
+def _repo(tmp_path: Path) -> Path:
+    _git(tmp_path, "init", "-q")
+    _git(tmp_path, "config", "user.email", "test@example.com")
+    _git(tmp_path, "config", "user.name", "Test")
+    initialize(tmp_path)
+    # A first commit, so the commits under test have a parent: `git diff-tree`
+    # lists no files for a root commit.
+    _git(tmp_path, "commit", "-q", "--allow-empty", "-m", "initial")
+    return tmp_path
+
+
+def _commit(root: Path, message: str, files: dict[str, str]) -> None:
+    for rel, text in files.items():
+        path = root / rel
+        path.parent.mkdir(parents=True, exist_ok=True)
+        path.write_text(text, encoding="utf-8")
+        _git(root, "add", rel)
+    _git(root, "commit", "-q", "-m", message)
+
+
+def test_location_skips_projectmem_files(tmp_path):
+    root = _repo(tmp_path)
+    _commit(root, "fix: guard the login submit", {
+        ".projectmem/summary.md": "# regenerated\n",
+        "src/login.py": "print('login')\n",
+    })
+
+    _capture_commit(root)
+
+    event = read_events(root)[-1]
+    assert event.type == "fix"
+    assert event.location == "src/login.py"
+    # Only the location moves; the event still records every file it touched.
+    assert ".projectmem/summary.md" in event.files
+
+
+def test_a_memory_only_commit_has_no_location(tmp_path):
+    """Nothing to point at is better than pointing at summary.md."""
+    root = _repo(tmp_path)
+    _commit(root, "fix: tidy the summary", {
+        ".projectmem/summary.md": "# regenerated\n",
+    })
+
+    _capture_commit(root)
+
+    event = read_events(root)[-1]
+    assert event.type == "fix"
+    assert event.location is None