feat: Phase 1 - Discord bridge with unified user identity

Implements unified cross-server memory system for Miku bot:

**Core Changes:**
- discord_bridge plugin with 3 hooks for metadata enrichment
- Unified user identity: discord_user_{id} across servers and DMs
- Minimal filtering: skip only trivial messages (lol, k, 1-2 chars)
- Marks all memories as consolidated=False for Phase 2 processing

**Testing:**
- test_phase1.py validates cross-server memory recall
- PHASE1_TEST_RESULTS.md documents successful validation
- Cross-server test: User says 'blue' in Server A, Miku remembers in Server B ✅

**Documentation:**
- IMPLEMENTATION_PLAN.md - Complete architecture and roadmap
- Phase 2 (sleep consolidation) ready for implementation

This lays the foundation for human-like memory consolidation.

cheshire-cat/cat/plugins/discord_bridge/discord_bridge.py

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+"""
+Discord Bridge Plugin for Cheshire Cat
+
+This plugin enriches Cat's memory system with Discord context:
+- Unified user identity across all servers and DMs
+- Guild/channel metadata for context tracking
+- Minimal filtering before storage (only skip obvious junk)
+- Marks memories as unconsolidated for nightly processing
+
+Phase 1 Implementation
+"""
+
+from cat.mad_hatter.decorators import hook
+from datetime import datetime
+import re
+
+
+@hook(priority=100)
+def before_cat_reads_message(user_message_json: dict, cat) -> dict:
+    """
+    Enrich incoming message with Discord metadata.
+    This runs BEFORE the message is processed.
+    """
+    # Extract Discord context from working memory or metadata
+    # These will be set by the Discord bot when calling the Cat API
+    guild_id = cat.working_memory.get('guild_id')
+    channel_id = cat.working_memory.get('channel_id')
+    
+    # Add to message metadata for later use
+    if 'metadata' not in user_message_json:
+        user_message_json['metadata'] = {}
+    
+    user_message_json['metadata']['guild_id'] = guild_id or 'dm'
+    user_message_json['metadata']['channel_id'] = channel_id
+    user_message_json['metadata']['timestamp'] = datetime.now().isoformat()
+    
+    return user_message_json
+
+
+@hook(priority=100)
+def before_cat_stores_episodic_memory(doc, cat):
+    """
+    Filter and enrich memories before storage.
+    
+    Phase 1: Minimal filtering
+    - Skip only obvious junk (1-2 char messages, pure reactions)
+    - Store everything else temporarily
+    - Mark as unconsolidated for nightly processing
+    """
+    message = doc.page_content.strip()
+    
+    # Skip only the most trivial messages
+    skip_patterns = [
+        r'^\w{1,2}$',  # 1-2 character messages: "k", "ok"
+        r'^(lol|lmao|haha|hehe|xd|rofl)$',  # Pure reactions
+        r'^:[\w_]+:$',  # Discord emoji only: ":smile:"
+    ]
+    
+    for pattern in skip_patterns:
+        if re.match(pattern, message.lower()):
+            print(f"🗑️  [Discord Bridge] Skipping trivial message: {message}")
+            return None  # Don't store at all
+    
+    # Add Discord metadata to memory
+    doc.metadata['consolidated'] = False  # Needs nightly processing
+    doc.metadata['stored_at'] = datetime.now().isoformat()
+    
+    # Get Discord context from working memory
+    guild_id = cat.working_memory.get('guild_id')
+    channel_id = cat.working_memory.get('channel_id')
+    
+    doc.metadata['guild_id'] = guild_id or 'dm'
+    doc.metadata['channel_id'] = channel_id
+    doc.metadata['source'] = 'discord'
+    
+    print(f"💾 [Discord Bridge] Storing memory (unconsolidated): {message[:50]}...")
+    print(f"   User: {cat.user_id}, Guild: {doc.metadata['guild_id']}, Channel: {channel_id}")
+    
+    return doc
+
+
+@hook(priority=50)
+def after_cat_recalls_memories(memory_docs, cat):
+    """
+    Log memory recall for debugging.
+    Can be used to filter by guild_id if needed in the future.
+    """
+    if memory_docs:
+        print(f"🧠 [Discord Bridge] Recalled {len(memory_docs)} memories for user {cat.user_id}")
+        # Show which guilds the memories are from
+        guilds = set(doc.metadata.get('guild_id', 'unknown') for doc in memory_docs)
+        print(f"   From guilds: {', '.join(guilds)}")
+    
+    return memory_docs
+
+
+# Plugin metadata
+__version__ = "1.0.0"
+__description__ = "Discord bridge with unified user identity and sleep consolidation support"

cheshire-cat/cat/plugins/discord_bridge/plugin.json

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+{
+  "name": "Discord Bridge",
+  "description": "Discord integration with unified user identity and sleep consolidation support",
+  "author_name": "Miku Bot Team",
+  "author_url": "",
+  "plugin_url": "",
+  "tags": "discord, memory, consolidation",
+  "thumb": "",
+  "version": "1.0.0"
+}

cheshire-cat/cat/plugins/discord_bridge/settings.json

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+{}