refactor: organize agent harness courses

learn-pi-agent/s08_context_resources/code.ts

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+// s08: Context Resources — mini Pi 的第 8 版
+//
+// 把项目资料组装进 systemPrompt（对齐 Pi buildSystemPrompt），不再是独立 context 字段。
+// 词汇边界：本章新增 ContextResource / ResourceLoader / buildSystemPrompt / systemPrompt。
+// 关键（对齐 Pi Context）：ProviderInput 加 systemPrompt（资料进去）；tools 保留（R1）。
+
+declare const process: {
+  exitCode?: number;
+};
+
+// —— 停止原因（s04 起）——
+export type StopReason = "stop" | "toolUse" | "error";
+
+// —— 消息 ——
+export type UserMessage = { role: "user"; content: string };
+export type AssistantMessage = { role: "assistant"; content: string; stopReason: StopReason };
+export type ToolResultMessage = { role: "toolResult"; toolCallId: string; content: string };
+export type AgentMessage = UserMessage | AssistantMessage | ToolResultMessage;
+
+// —— 会话历史（s07 起）——
+export type SessionEntry = { id: string; parentId: string | null; message: AgentMessage };
+export class SessionTree {
+  private entries = new Map<string, SessionEntry>();
+  private activeLeafId: string | null = null;
+  private counter = 0;
+  append(message: AgentMessage): SessionEntry {
+    const entry = { id: `e${++this.counter}`, parentId: this.activeLeafId, message };
+    this.entries.set(entry.id, entry);
+    this.activeLeafId = entry.id;
+    return entry;
+  }
+  moveTo(entryId: string): void {
+    if (!this.entries.has(entryId)) throw new Error(`unknown entry: ${entryId}`);
+    this.activeLeafId = entryId;
+  }
+  currentPath(): AgentMessage[] {
+    const path: AgentMessage[] = [];
+    let cursor = this.activeLeafId;
+    while (cursor) {
+      const entry = this.entries.get(cursor);
+      if (!entry) break;
+      path.push(entry.message);
+      cursor = entry.parentId;
+    }
+    return path.reverse();
+  }
+  allEntries(): SessionEntry[] { return [...this.entries.values()]; }
+}
+
+// —— core 状态（s06 起：model 跨轮配置）——
+export type AgentState = { session: SessionTree; model: string };
+
+// —— 工具契约 ——
+export type ToolSpec = { name: string; description: string; input: Record<string, string> };
+export type ToolHandler = (input: Record<string, string>) => string;
+export type ToolCall = { id: string; name: string; input: Record<string, string> };
+export type Tool = { spec: ToolSpec; handler: ToolHandler };
+export class ToolRegistry {
+  private tools = new Map<string, Tool>();
+  register(tool: Tool): void { this.tools.set(tool.spec.name, tool); }
+  getSpecs(): ToolSpec[] { return [...this.tools.values()].map((tool) => tool.spec); }
+  count(): number { return this.tools.size; }
+  run(call: ToolCall): string {
+    const tool = this.tools.get(call.name);
+    if (!tool) return `unknown tool: ${call.name}`;
+    return tool.handler(call.input);
+  }
+}
+
+// ============ s08 新增：项目资料（组装进 systemPrompt）============
+
+export type ContextResource = { kind: "agents" | "skill" | "prompt"; name: string; content: string };
+
+// U2 全局唯一：s08 定义，s11 会给 load 加 trust 参数（U1）。
+export class ResourceLoader {
+  constructor(private resources: ContextResource[]) {}
+  load(): ContextResource[] {
+    return this.resources.map((resource) => ({ ...resource }));
+  }
+}
+
+// 把资源组装进 systemPrompt（对齐 Pi buildSystemPrompt），每份带上来源标记。
+export function buildSystemPrompt(resources: ContextResource[]): string {
+  return resources
+    .map((resource) => `[${resource.kind}:${resource.name}]\n${resource.content}`)
+    .join("\n\n");
+}
+
+// —— provider 对外（对齐 Pi Context：systemPrompt + messages + tools）——
+export type ProviderMessage =
+  | { role: "user" | "assistant"; content: string }
+  | { role: "toolResult"; toolCallId: string; content: string };
+
+export type ProviderInput = {
+  systemPrompt: string;   // s08 新增：项目资料组装进去（对齐 Pi Context.systemPrompt）
+  messages: ProviderMessage[];
+  tools: ToolSpec[];      // s02 起，保留（R1）
+};
+
+export type ProviderEvent =
+  | { type: "message_start" }
+  | { type: "text_delta"; text: string }
+  | { type: "tool_call"; call: ToolCall }
+  | { type: "message_end"; stopReason: StopReason };
+
+export interface Provider {
+  stream(input: ProviderInput): AsyncGenerator<ProviderEvent>;
+}
+
+export type Output = { log(line: string): void };
+export function createConsoleOutput(): Output { return { log: (line) => console.log(line) }; }
+
+// —— s05 起：执行插口 ——
+export type BeforeToolCallResult = { type: "allow" } | { type: "block"; reason: string };
+export type ToolHooks = {
+  beforeToolCall?: (call: ToolCall) => BeforeToolCallResult;
+  afterToolCall?: (call: ToolCall, result: string) => string;
+};
+export function executeToolCall(registry: ToolRegistry, hooks: ToolHooks, call: ToolCall): ToolResultMessage {
+  const before = hooks.beforeToolCall?.(call) ?? { type: "allow" };
+  if (before.type === "block") {
+    return { role: "toolResult", toolCallId: call.id, content: `blocked: ${before.reason}` };
+  }
+  let result: string;
+  try { result = registry.run(call); }
+  catch (error) { result = `error: ${error instanceof Error ? error.message : String(error)}`; }
+  const finalResult = hooks.afterToolCall?.(call, result) ?? result;
+  return { role: "toolResult", toolCallId: call.id, content: finalResult };
+}
+
+// —— s06 起快照（s08：加 systemPrompt）——
+export type TurnSnapshot = {
+  systemPrompt: string;
+  messages: ProviderMessage[];
+  tools: ToolSpec[];
+};
+
+function toProviderMessages(messages: AgentMessage[]): ProviderMessage[] {
+  return messages.map((message) => {
+    if (message.role === "toolResult") {
+      return { role: "toolResult", toolCallId: message.toolCallId, content: message.content };
+    }
+    return { role: message.role, content: message.content };
+  });
+}
+
+// s08：createTurnSnapshot 多接收 loader，把 systemPrompt 一起拍进快照。
+export function createTurnSnapshot(
+  state: AgentState,
+  registry: ToolRegistry,
+  loader: ResourceLoader,
+): TurnSnapshot {
+  return {
+    systemPrompt: buildSystemPrompt(loader.load()),
+    messages: toProviderMessages(state.session.currentPath()),
+    tools: registry.getSpecs(),
+  };
+}
+
+export function buildProviderInputFromSnapshot(
+  snapshot: TurnSnapshot,
+  state: AgentState,
+): ProviderInput {
+  return {
+    systemPrompt: snapshot.systemPrompt,
+    messages: toProviderMessages(state.session.currentPath()),
+    tools: snapshot.tools,
+  };
+}
+
+// ============ 构造函数 ============
+export function createInitialState(model = "demo-small"): AgentState {
+  return { session: new SessionTree(), model };
+}
+export function createUserMessage(content: string): UserMessage { return { role: "user", content }; }
+
+// ============ 工具循环（不变，用 snapshot）============
+const MAX_TURNS = 8;
+export async function runEventedToolLoop(
+  state: AgentState, provider: Provider, registry: ToolRegistry,
+  hooks: ToolHooks, snapshot: TurnSnapshot, output: Output,
+): Promise<AssistantMessage> {
+  let turns = 0;
+  while (true) {
+    turns += 1;
+    if (turns > MAX_TURNS) {
+      const stopped: AssistantMessage = { role: "assistant", content: "(达到最大轮次，停止)", stopReason: "stop" };
+      state.session.append(stopped);
+      return stopped;
+    }
+    const providerInput = buildProviderInputFromSnapshot(snapshot, state);
+    let content = "";
+    let stopReason: StopReason = "stop";
+    let sawToolCall = false;
+    for await (const event of provider.stream(providerInput)) {
+      if (event.type === "message_start") output.log("message_start");
+      else if (event.type === "text_delta") { output.log(`text_delta: ${event.text}`); content += event.text; }
+      else if (event.type === "tool_call") {
+        sawToolCall = true;
+        output.log(`tool_call: ${event.call.name}`);
+        const resultMessage = executeToolCall(registry, hooks, event.call);
+        state.session.append(resultMessage);
+        output.log(`tool_result: ${resultMessage.content}`);
+      } else if (event.type === "message_end") { stopReason = event.stopReason; output.log(`message_end: ${stopReason}`); }
+    }
+    if (!sawToolCall || stopReason !== "toolUse") {
+      const assistant: AssistantMessage = { role: "assistant", content, stopReason };
+      state.session.append(assistant);
+      return assistant;
+    }
+  }
+}
+
+// ============ Demo Provider（保留，累积）============
+export class DemoProvider implements Provider {
+  public lastInput: ProviderInput | undefined;
+  async *stream(input: ProviderInput): AsyncGenerator<ProviderEvent> {
+    this.lastInput = input;
+    const last = input.messages[input.messages.length - 1];
+    yield { type: "message_start" };
+    if (last?.role === "toolResult") {
+      yield { type: "text_delta", text: `工具结果是：${last.content}` };
+      yield { type: "message_end", stopReason: "stop" };
+      return;
+    }
+    yield { type: "tool_call", call: { id: "call_1", name: "current_time", input: {} } };
+    yield { type: "message_end", stopReason: "toolUse" };
+  }
+}
+
+// ============ 演示脚手架 ============
+
+function createRegistry(): ToolRegistry {
+  const registry = new ToolRegistry();
+  registry.register({
+    spec: { name: "current_time", description: "返回一个固定的演示时间", input: {} },
+    handler: () => "2026-01-01T00:00:00Z",
+  });
+  return registry;
+}
+
+function createLoader(): ResourceLoader {
+  return new ResourceLoader([
+    { kind: "agents", name: "AGENTS.md", content: "Use concise engineering explanations." },
+    { kind: "skill", name: "repo-review", content: "Inspect package.json first. Then summarize risks." },
+    { kind: "prompt", name: "summarize", content: "Return three bullets and one next step." },
+  ]);
+}
+
+async function main(): Promise<void> {
+  const output = createConsoleOutput();
+  const state = createInitialState("demo-small");
+  const registry = createRegistry();
+  const loader = createLoader();
+
+  output.log("s08: Context Resources");
+  output.log("");
+
+  const resources = loader.load();
+  output.log("[resources]");
+  for (const resource of resources) {
+    output.log(`${resource.kind}: ${resource.name}`);
+  }
+  output.log("");
+
+  // 一轮开始：push 用户消息，拍快照（含 systemPrompt）。
+  state.session.append(createUserMessage("请总结这个项目"));
+  const snapshot = createTurnSnapshot(state, registry, loader);
+  const input = buildProviderInputFromSnapshot(snapshot, state);
+
+  output.log("[provider input]");
+  output.log(`systemPrompt blocks: ${resources.length}`);
+  output.log(`messages: ${input.messages.length}`);
+  output.log(`tools: ${input.tools.length}`);
+  output.log("");
+
+  output.log("[systemPrompt]");
+  output.log(input.systemPrompt);
+  output.log("");
+}
+
+main().catch((error: unknown) => {
+  console.error(error);
+  process.exitCode = 1;
+});