fix: only send tools to backends that support them (cloud)

The MI50 llama.cpp server 500s on the `tools` param unless launched with
--jinja, so sending tools to mi50 broke chat on that backend. Gate tools to
TOOL_BACKENDS={"cloud"} for now; mi50 chat works again (just without tools).
Add "mi50" once its server runs with --jinja.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/chat.py

@@ -18,6 +18,10 @@ RECALL_K = 3  # raw cross-session "sharp detail" hits
 RECENT_N = 10  # raw turns of the current session
 SUMMARY_K = 3  # other-session gists
 MAX_TOOL_ROUNDS = 5  # cap tool-call iterations per turn
+# Backends that support function-calling. The MI50's llama.cpp server only does
+# tools when launched with --jinja; until it is, keep tools to cloud so MI50 chat
+# doesn't 500 on the tools param. Add "mi50" here once that flag is set.
+TOOL_BACKENDS = {"cloud"}
 
 
 def _summary_note(summaries: list[memory.Summary]) -> Message:
@@ -126,7 +130,7 @@ def respond(session_id: str, user_msg: str, backend: Backend = "cloud") -> str:
 
     # Tool loop: offer Lyra her tools; if she calls one, run it and feed the
     # result back so she can continue, until she returns a normal text reply.
-    tool_specs = toolkit.specs() if backend in ("cloud", "mi50") else None
+    tool_specs = toolkit.specs() if backend in TOOL_BACKENDS else None
     ctx = {"session_id": session_id, "backend": backend}
     reply = ""
     for _ in range(MAX_TOOL_ROUNDS):