fix(memory): case-insensitive fact deduplication and positive reinforcement detection (#1804)

* fix(memory): case-insensitive fact deduplication and positive reinforcement detection

Two fixes to the memory system:

1. _fact_content_key() now lowercases content before comparison, preventing
   semantically duplicate facts like "User prefers Python" and "user prefers
   python" from being stored separately.

2. Adds detect_reinforcement() to MemoryMiddleware (closes #1719), mirroring
   detect_correction(). When users signal approval ("yes exactly", "perfect",
   "完全正确", etc.), the memory updater now receives reinforcement_detected=True
   and injects a hint prompting the LLM to record confirmed preferences and
   behaviors with high confidence.

   Changes across the full signal path:
   - memory_middleware.py: _REINFORCEMENT_PATTERNS + detect_reinforcement()
   - queue.py: reinforcement_detected field in ConversationContext and add()
   - updater.py: reinforcement_detected param in update_memory() and
     update_memory_from_conversation(); builds reinforcement_hint alongside
     the existing correction_hint

Tests: 11 new tests covering deduplication, hint injection, and signal
detection (Chinese + English patterns, window boundary, conflict with correction).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(memory): address Copilot review comments on reinforcement detection

- Tighten _REINFORCEMENT_PATTERNS: remove 很好, require punctuation/end-of-string boundaries on remaining patterns, split this-is-good into stricter variants
- Suppress reinforcement_detected when correction_detected is true to avoid mixed-signal noise
- Use casefold() instead of lower() for Unicode-aware fact deduplication
- Add missing test coverage for reinforcement_detected OR merge and forwarding in queue

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/packages/harness/deerflow/agents/memory/updater.py

@@ -246,7 +246,7 @@ def _fact_content_key(content: Any) -> str | None:
     stripped = content.strip()
     if not stripped:
         return None
-    return stripped
+    return stripped.casefold()
 
 
 class MemoryUpdater:
@@ -272,6 +272,7 @@ class MemoryUpdater:
         thread_id: str | None = None,
         agent_name: str | None = None,
         correction_detected: bool = False,
+        reinforcement_detected: bool = False,
     ) -> bool:
         """Update memory based on conversation messages.
 
@@ -280,6 +281,7 @@ class MemoryUpdater:
             thread_id: Optional thread ID for tracking source.
             agent_name: If provided, updates per-agent memory. If None, updates global memory.
             correction_detected: Whether recent turns include an explicit correction signal.
+            reinforcement_detected: Whether recent turns include a positive reinforcement signal.
 
         Returns:
             True if update was successful, False otherwise.
@@ -310,6 +312,14 @@ class MemoryUpdater:
                     "and record the correct approach as a fact with category "
                     '"correction" and confidence >= 0.95 when appropriate.'
                 )
+            if reinforcement_detected:
+                reinforcement_hint = (
+                    "IMPORTANT: Positive reinforcement signals were detected in this conversation. "
+                    "The user explicitly confirmed the agent's approach was correct or helpful. "
+                    "Record the confirmed approach, style, or preference as a fact with category "
+                    '"preference" or "behavior" and confidence >= 0.9 when appropriate.'
+                )
+                correction_hint = (correction_hint + "\n" + reinforcement_hint).strip() if correction_hint else reinforcement_hint
 
             prompt = MEMORY_UPDATE_PROMPT.format(
                 current_memory=json.dumps(current_memory, indent=2),
@@ -441,6 +451,7 @@ def update_memory_from_conversation(
     thread_id: str | None = None,
     agent_name: str | None = None,
     correction_detected: bool = False,
+    reinforcement_detected: bool = False,
 ) -> bool:
     """Convenience function to update memory from a conversation.
 
@@ -449,9 +460,10 @@ def update_memory_from_conversation(
         thread_id: Optional thread ID.
         agent_name: If provided, updates per-agent memory. If None, updates global memory.
         correction_detected: Whether recent turns include an explicit correction signal.
+        reinforcement_detected: Whether recent turns include a positive reinforcement signal.
 
     Returns:
         True if successful, False otherwise.
     """
     updater = MemoryUpdater()
-    return updater.update_memory(messages, thread_id, agent_name, correction_detected)
+    return updater.update_memory(messages, thread_id, agent_name, correction_detected, reinforcement_detected)