feat: Introduce event timeline and handler system

worker/examples/timeline_basic.rs

@@ -0,0 +1,132 @@
+//! Timeline使用例
+//!
+//! 設計ドキュメントに基づいたTimelineの使用パターンを示すサンプル
+
+use worker::{
+    Event, Handler, TextBlockEvent, TextBlockKind, Timeline,
+    ToolUseBlockEvent, ToolUseBlockKind, UsageEvent, UsageKind,
+};
+
+fn main() {
+    // シミュレートされたイベントストリーム
+    let events = simulate_llm_response();
+
+    // Timelineを作成し、ハンドラーを登録
+    let mut timeline = Timeline::new();
+
+    // Usage収集ハンドラー
+    timeline.on_usage(UsageAccumulator::new());
+
+    // テキスト収集ハンドラー
+    timeline.on_text_block(TextCollector::new());
+
+    // ツール呼び出し収集ハンドラー
+    timeline.on_tool_use_block(ToolCallCollector::new());
+
+    // イベントをディスパッチ
+    for event in &events {
+        timeline.dispatch(event);
+    }
+
+    println!("Timeline example completed!");
+    println!("Events processed: {}", events.len());
+}
+
+/// LLMレスポンスをシミュレート
+fn simulate_llm_response() -> Vec<Event> {
+    vec![
+        // テキストブロック
+        Event::text_block_start(0),
+        Event::text_delta(0, "Hello, "),
+        Event::text_delta(0, "I can help you with that."),
+        Event::text_block_stop(0, None),
+        // 使用量
+        Event::usage(100, 50),
+        // ツール呼び出し
+        Event::tool_use_start(1, "call_abc123", "get_weather"),
+        Event::tool_input_delta(1, r#"{"city":"#),
+        Event::tool_input_delta(1, r#""Tokyo"}"#),
+        Event::tool_use_stop(1),
+        // 最終的な使用量
+        Event::usage(100, 75),
+    ]
+}
+
+// =============================================================================
+// Example Handlers (defined in example, not in library)
+// =============================================================================
+
+/// 使用量を累積するハンドラー
+struct UsageAccumulator {
+    total_tokens: u64,
+}
+
+impl UsageAccumulator {
+    fn new() -> Self {
+        Self { total_tokens: 0 }
+    }
+}
+
+impl Handler<UsageKind> for UsageAccumulator {
+    type Scope = ();
+    fn on_event(&mut self, _scope: &mut (), usage: &UsageEvent) {
+        self.total_tokens += usage.total_tokens.unwrap_or(0);
+    }
+}
+
+/// テキストを収集するハンドラー
+struct TextCollector {
+    results: Vec<String>,
+}
+
+impl TextCollector {
+    fn new() -> Self {
+        Self { results: Vec::new() }
+    }
+}
+
+impl Handler<TextBlockKind> for TextCollector {
+    type Scope = String;
+    fn on_event(&mut self, buffer: &mut String, event: &TextBlockEvent) {
+        match event {
+            TextBlockEvent::Start(_) => {}
+            TextBlockEvent::Delta(s) => buffer.push_str(s),
+            TextBlockEvent::Stop(_) => {
+                self.results.push(std::mem::take(buffer));
+            }
+        }
+    }
+}
+
+/// ツール呼び出しを収集するハンドラー
+struct ToolCallCollector {
+    calls: Vec<(String, String)>, // (name, args)
+}
+
+impl ToolCallCollector {
+    fn new() -> Self {
+        Self { calls: Vec::new() }
+    }
+}
+
+#[derive(Default)]
+struct ToolCallScope {
+    name: String,
+    args: String,
+}
+
+impl Handler<ToolUseBlockKind> for ToolCallCollector {
+    type Scope = ToolCallScope;
+    fn on_event(&mut self, scope: &mut ToolCallScope, event: &ToolUseBlockEvent) {
+        match event {
+            ToolUseBlockEvent::Start(s) => scope.name = s.name.clone(),
+            ToolUseBlockEvent::InputJsonDelta(json) => scope.args.push_str(json),
+            ToolUseBlockEvent::Stop(_) => {
+                self.calls.push((
+                    std::mem::take(&mut scope.name),
+                    std::mem::take(&mut scope.args),
+                ));
+            }
+        }
+    }
+}