feat(grid-agent): add generic LLM tool loop (#119)

crates/metacrate-grid-agent/src/lib.rs

@@ -6,7 +6,9 @@
 
 pub mod backend;
 pub mod config;
+pub mod llm;
 pub mod service;
+pub mod tool_loop;
 pub mod types;
 
 #[cfg(feature = "live-grid")]
@@ -17,7 +19,15 @@ pub use config::{
     GridConnection, Limits, LlmConnection, MapEnvironment, OperatingMode, SecretString,
     StdEnvironment, Timeouts,
 };
+pub use llm::{
+    Completion, CompletionMessage, ContentPart, ImageDetail, LlmClient, LlmError,
+    LlmTransportLimits, ToolDefinition, ToolSchema, Usage,
+};
 pub use service::{AgentService, ServiceError, ServiceHandle, ServiceState};
+pub use tool_loop::{
+    HistorySummarizer, SessionGeneration, ToolExecution, ToolExecutor, ToolFuture, ToolLoop,
+    ToolLoopError, ToolLoopLimits, ToolLoopOutcome,
+};
 pub use types::{
     BoundaryError, BoundedText, BoundedVec, ControlCommand, Conversation, ConversationMessage,
     GridEvent, GridEventKind, LlmRequest, LlmResult, MessageRole, ObservableEvent, PolicyDecision,