3.2: Create AgentRegistry

New file cheddahbot/agent_registry.py. Holds multiple Agent instances
keyed by name with methods: register(), get(), list_agents(), and
default property. First registered agent is the default.

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

cheddahbot/agent_registry.py

@@ -0,0 +1,49 @@
+"""Multi-agent registry.
+
+Holds multiple Agent instances keyed by name. The first registered
+agent is the default (used by scheduler and as fallback).
+"""
+
+from __future__ import annotations
+
+import logging
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from .agent import Agent
+
+log = logging.getLogger(__name__)
+
+
+class AgentRegistry:
+    """Registry of named Agent instances."""
+
+    def __init__(self):
+        self._agents: dict[str, Agent] = {}
+        self._default_name: str | None = None
+
+    def register(self, name: str, agent: Agent, is_default: bool = False):
+        """Register an agent by name."""
+        self._agents[name] = agent
+        if is_default or self._default_name is None:
+            self._default_name = name
+        log.info("Registered agent: %s (default=%s)", name, name == self._default_name)
+
+    def get(self, name: str) -> Agent | None:
+        return self._agents.get(name)
+
+    def list_agents(self) -> list[str]:
+        return list(self._agents.keys())
+
+    @property
+    def default(self) -> Agent | None:
+        if self._default_name:
+            return self._agents.get(self._default_name)
+        return None
+
+    @property
+    def default_name(self) -> str:
+        return self._default_name or "default"
+
+    def __len__(self) -> int:
+        return len(self._agents)