Fix memory dedup to use exact entry matching

anton/memory/hippocampus.py

@@ -233,8 +233,8 @@ def encode_rule(
         else:
             content = "# Rules\n\n## Always\n\n## Never\n\n## When\n"
 
-        # Check for duplicate (same text, ignoring metadata)
-        if text in content:
+        # Check for duplicate (exact entry match, ignoring metadata)
+        if text in self._extract_entry_texts(content):
             return
 
         # Find the section and append
@@ -296,9 +296,9 @@ def encode_lesson(
                 mode="write",
             )
         else:
-            # Check for duplicate
+            # Check for duplicate (exact entry match, ignoring metadata)
             existing = self._lessons_path.read_text(encoding="utf-8")
-            if text in existing:
+            if text in self._extract_entry_texts(existing):
                 return
             self._encode_with_lock(self._lessons_path, entry, mode="append")
 
@@ -315,7 +315,7 @@ def encode_lesson(
                 )
             else:
                 existing = topic_path.read_text(encoding="utf-8")
-                if text not in existing:
+                if text not in self._extract_entry_texts(existing):
                     self._encode_with_lock(topic_path, entry, mode="append")
 
     def rewrite_identity(self, entries: list[str]) -> None:
@@ -381,6 +381,27 @@ def _encode_with_lock(self, path: Path, text: str, mode: str = "append") -> None
                         import fcntl
                         fcntl.flock(f.fileno(), fcntl.LOCK_UN)
 
+    @staticmethod
+    def _extract_entry_texts(content: str) -> set[str]:
+        """Extract the set of normalized entry texts from a markdown memory file.
+
+        Strips the leading ``- ``, trailing metadata comments, and whitespace
+        so that dedup comparisons are exact-match on the *meaning* line only.
+        """
+        texts: set[str] = set()
+        for line in content.splitlines():
+            stripped = line.strip()
+            if not stripped.startswith("- "):
+                continue
+            # Remove leading "- "
+            entry = stripped[2:]
+            # Remove trailing <!-- ... --> metadata
+            entry = re.sub(r"\s*<!--[\s\S]*?-->\s*$", "", entry)
+            entry = entry.strip()
+            if entry:
+                texts.add(entry)
+        return texts
+
     @staticmethod
     def _sanitize_slug(name: str) -> str:
         """Sanitize a topic name into a safe file slug."""

tests/test_hippocampus.py

@@ -134,6 +134,20 @@ def test_includes_metadata(self, hc, mem_dir):
         assert "confidence:high" in content
         assert "source:user" in content
 
+    def test_allows_superstring_of_existing(self, hc, mem_dir):
+        """A longer, more specific rule should NOT be blocked by a shorter one."""
+        hc.encode_rule("Use httpx", kind="always")
+        hc.encode_rule("Use httpx with timeout=15", kind="always")
+        content = (mem_dir / "rules.md").read_text()
+        assert "Use httpx with timeout=15" in content
+
+    def test_allows_substring_of_existing(self, hc, mem_dir):
+        """A shorter rule should NOT be blocked by a longer one containing it."""
+        hc.encode_rule("Use httpx with timeout=15", kind="always")
+        hc.encode_rule("Use httpx", kind="always")
+        content = (mem_dir / "rules.md").read_text()
+        assert content.count("Use httpx") == 2  # both present
+
 
 class TestEncodeLesson:
     def test_creates_lessons_file(self, hc, mem_dir):
@@ -158,6 +172,20 @@ def test_no_topic_no_topic_file(self, hc, mem_dir):
         hc.encode_lesson("Simple fact")
         assert not (mem_dir / "topics").exists() or not any((mem_dir / "topics").iterdir())
 
+    def test_allows_superstring_of_existing_lesson(self, hc, mem_dir):
+        """A more detailed lesson should NOT be blocked by a shorter one."""
+        hc.encode_lesson("CoinGecko limits at 50/min")
+        hc.encode_lesson("CoinGecko limits at 50/min for free tier accounts")
+        content = (mem_dir / "lessons.md").read_text()
+        assert "for free tier accounts" in content
+
+    def test_skips_exact_duplicate_with_metadata(self, hc, mem_dir):
+        """Exact same text should be blocked even when metadata differs."""
+        hc.encode_lesson("Fact one", topic="api")
+        hc.encode_lesson("Fact one", topic="other")
+        content = (mem_dir / "lessons.md").read_text()
+        assert content.count("Fact one") == 1
+
 
 class TestRewriteIdentity:
     def test_creates_profile(self, hc, mem_dir):