Expose per-session settings (a model picker, a mode, a capability-gated boolean) as
session config options, change them with session/set_config_option, and push agent-side
changes with config_option_update. One agent, written twice: builder API and annotations.
No API key required.
Full tutorial: https://lab.pollack.ai/docs/acp-java-sdk/tutorial/33-session-config-options
./mvnw package -pl module-33-session-config-options -q
./mvnw exec:java -pl module-33-session-config-options