Phase 7: Agent Selector — per-agent soul.md + ChromaDB memory filtering

- Agent dropdown UI (chip button + hidden select) in composer header
- Session.agent field persists agent selection across refresh
- soul.md loaded per-agent via ephemeral_system_prompt injection
- ChromaDB memory filtered by agent topic (lotus/, sunflower/, etc.)
- Fixed streaming.py: agent→_ai_agent variable shadowing (lines 1161, 1163)
- New API endpoints: /api/agents/topology, /api/agents/memory/search
- Agent metadata registry with emoji, name, description per Tier-2 agent

api/agents_memory.py

@@ -3,6 +3,55 @@ Phase 5 — Memory Search (ChromaDB)
 Appended to agents.py functions for Memory Search.
 """
 import chromadb
+import os
+from pathlib import Path
+
+HERMES_HOME = Path(os.environ.get("HERMES_HOME", os.path.expanduser("~/.hermes")))
+
+
+def _get_agent_soul(agent_id: str) -> str | None:
+    """
+    Load soul.md for a specific agent.
+
+    Searches in this order:
+    1. ~/.hermes/agents/{agent_id}/soul.md
+    2. ~/.hermes/agents/{agent_id}/SOUL.md
+
+    Returns None if not found.
+    """
+    if not agent_id or agent_id == "rose":
+        return None  # Rose uses the global HERMES_HOME/SOUL.md
+
+    for fname in ("soul.md", "SOUL.md"):
+        path = HERMES_HOME / "agents" / agent_id / fname
+        if path.exists():
+            try:
+                content = path.read_text(encoding="utf-8").strip()
+                if content:
+                    return content
+            except Exception:
+                pass
+    return None
+
+
+def _get_agent_memory_context(agent_id: str, query: str, limit: int = 5) -> str | None:
+    """
+    Build a memory context string by searching ChromaDB for the agent's memories.
+
+    Searches rose_memory collection filtered by topic matching "{agent_id}/".
+    Returns formatted text block or None if nothing found.
+    """
+    if not agent_id or agent_id == "rose":
+        return None
+
+    matches = _search_agent_memory(agent_id, query, limit=limit)
+    if not matches:
+        return None
+
+    blocks = []
+    for m in matches:
+        blocks.append(f"## {m['topic']}\n{m['content'][:300]}")
+    return "\n\n".join(blocks) if blocks else None
 
 
 def _get_chroma_client():