feat: merge 2nd round from all rcc/* sessions

- api: tool_use parsing, message_delta, request_id tracking, retry logic
- tools: extended tool suite (WebSearch, WebFetch, Agent, etc.)
- cli: live streamed conversations, session restore, compact commands
- runtime: config loading, system prompt builder, token usage, compaction

rust/crates/runtime/src/lib.rs

@@ -1,11 +1,22 @@
 mod bootstrap;
+mod compact;
+mod config;
 mod conversation;
 mod json;
 mod permissions;
 mod prompt;
 mod session;
+mod usage;
 
 pub use bootstrap::{BootstrapPhase, BootstrapPlan};
+pub use compact::{
+    compact_session, estimate_session_tokens, format_compact_summary,
+    get_compact_continuation_message, should_compact, CompactionConfig, CompactionResult,
+};
+pub use config::{
+    ConfigEntry, ConfigError, ConfigLoader, ConfigSource, RuntimeConfig,
+    CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
+};
 pub use conversation::{
     ApiClient, ApiRequest, AssistantEvent, ConversationRuntime, RuntimeError, StaticToolExecutor,
     ToolError, ToolExecutor, TurnSummary,
@@ -15,6 +26,8 @@ pub use permissions::{
     PermissionPrompter, PermissionRequest,
 };
 pub use prompt::{
-    prepend_bullets, SystemPromptBuilder, FRONTIER_MODEL_NAME, SYSTEM_PROMPT_DYNAMIC_BOUNDARY,
+    load_system_prompt, prepend_bullets, ContextFile, ProjectContext, PromptBuildError,
+    SystemPromptBuilder, FRONTIER_MODEL_NAME, SYSTEM_PROMPT_DYNAMIC_BOUNDARY,
 };
 pub use session::{ContentBlock, ConversationMessage, MessageRole, Session, SessionError};
+pub use usage::{TokenUsage, UsageTracker};