fix(memory): avoid duplicate summary injection

nanobot/agent/context.py

@@ -58,6 +58,7 @@ class ContextBuilder:
     _MAX_RECENT_HISTORY = 50
     _MAX_HISTORY_TOKENS = 8_000  # hard cap on recent history section size (tokens)
     _RUNTIME_CONTEXT_END = RUNTIME_CONTEXT_END
+    _SESSION_SUMMARY_HEADER_PREFIX = "Previous conversation summary (last active "
 
     def __init__(self, workspace: Path, timezone: str | None = None, disabled_skills: list[str] | None = None):
         self.workspace = workspace
@@ -115,17 +116,51 @@ class ContextBuilder:
             )
             if entries:
                 capped = entries[-self._MAX_RECENT_HISTORY:]
-                history_text = "\n".join(
-                    f"- [{e['timestamp']}] {e['content']}" for e in capped
+                capped = self._without_duplicate_session_summary(
+                    capped,
+                    session_key=session_key,
+                    session_summary=session_summary,
                 )
-                history_text = truncate_text_to_tokens(history_text, self._MAX_HISTORY_TOKENS)
-                parts.append("# Recent History\n\n" + history_text)
+                if capped:
+                    history_text = "\n".join(
+                        f"- [{e['timestamp']}] {e['content']}" for e in capped
+                    )
+                    history_text = truncate_text_to_tokens(
+                        history_text,
+                        self._MAX_HISTORY_TOKENS,
+                    )
+                    parts.append("# Recent History\n\n" + history_text)
 
         if session_summary:
             parts.append(f"[Archived Context Summary]\n\n{session_summary}")
 
         return "\n\n---\n\n".join(parts)
 
+    @classmethod
+    def _without_duplicate_session_summary(
+        cls,
+        entries: list[dict[str, Any]],
+        *,
+        session_key: str | None,
+        session_summary: str | None,
+    ) -> list[dict[str, Any]]:
+        """Drop the history entry already represented by the session summary."""
+        if not session_summary:
+            return entries
+        summary_content = session_summary
+        if session_summary.startswith(cls._SESSION_SUMMARY_HEADER_PREFIX):
+            _header, separator, content = session_summary.partition("):\n")
+            if separator and content:
+                summary_content = content
+        for index in range(len(entries) - 1, -1, -1):
+            entry = entries[index]
+            if (
+                entry.get("session_key") == session_key
+                and entry.get("content") == summary_content
+            ):
+                return [*entries[:index], *entries[index + 1:]]
+        return entries
+
     def _get_identity(self, channel: str | None = None, workspace: Path | None = None) -> str:
         """Get the core identity section."""
         root = workspace or self.workspace

tests/agent/test_auto_compact.py

@@ -724,6 +724,10 @@ class TestAutoCompactIntegration:
     async def test_full_lifecycle(self, tmp_path):
         loop = _make_loop(tmp_path, session_ttl_minutes=15)
         session = loop.sessions.get_or_create("cli:test")
+        overview = (
+            "IDLE_OVERVIEW_MARKER: User is learning English past tense. "
+            "Example: 'I walked to the store yesterday.'"
+        )
 
         # Phase 1: User has a conversation longer than the retained recent suffix
         session.add_message("user", "I'm learning English, teach me past tense")
@@ -745,7 +749,7 @@ class TestAutoCompactIntegration:
         # Phase 3: User returns with a new message
         loop.provider.chat_with_retry = AsyncMock(
             return_value=LLMResponse(
-                content="User is learning English past tense. Example: 'I walked to the store yesterday.'",
+                content=overview,
                 tool_calls=[],
             )
         )
@@ -759,6 +763,9 @@ class TestAutoCompactIntegration:
 
         # Phase 4: Verify
         session_after = loop.sessions.get_or_create("cli:test")
+        resumed_system_prompt = loop.provider.chat_with_retry.await_args_list[-1].kwargs[
+            "messages"
+        ][0]["content"]
 
         assert any(
             "past tense is used" in str(m.get("content", "")).lower()
@@ -773,6 +780,7 @@ class TestAutoCompactIntegration:
         assert not any(
             "[Resumed Session]" in str(m.get("content", "")) for m in session_after.messages
         )
+        assert resumed_system_prompt.count(overview) == 1
         # Runtime context end marker should NOT be persisted
         assert not any(
             "[/Runtime Context]" in str(m.get("content", "")) for m in session_after.messages

tests/agent/test_context_prompt_cache.py

@@ -112,6 +112,35 @@ def test_recent_history_injection_is_session_scoped(tmp_path) -> None:
     assert "legacy entry without session" not in prompt
 
 
+def test_session_summary_replaces_matching_recent_history_entry(tmp_path) -> None:
+    workspace = _make_workspace(tmp_path)
+    builder = ContextBuilder(workspace)
+    session_key = "telegram:chat-1"
+    overview = "CURRENT_SESSION_OVERVIEW_MARKER"
+
+    builder.memory.append_history("another session event", session_key=session_key)
+    summary_cursor = builder.memory.append_history(overview, session_key=session_key)
+    summary = f"Previous conversation summary (last active 2026-08-19T10:00:00):\n{overview}"
+
+    prompt = builder.build_system_prompt(
+        session_key=session_key,
+        session_summary=summary,
+    )
+
+    assert "# Recent History" in prompt
+    assert "another session event" in prompt
+    assert "[Archived Context Summary]" in prompt
+    assert prompt.count(overview) == 1
+
+    builder.memory.set_last_dream_cursor(summary_cursor)
+    processed_prompt = builder.build_system_prompt(
+        session_key=session_key,
+        session_summary=summary,
+    )
+    assert "# Recent History" not in processed_prompt
+    assert processed_prompt.count(overview) == 1
+
+
 def test_recent_history_injection_unified_excludes_cron_internals(tmp_path) -> None:
     workspace = _make_workspace(tmp_path)
     builder = ContextBuilder(workspace)