feat: 实现 PromptBuilder 段落构建器

src/core/prompt-builder.ts

@@ -0,0 +1,62 @@
+import type { PromptSection, SectionKind } from "./prompt-sections";
+
+export class PromptBuilder {
+  private sections: PromptSection[] = [];
+
+  head(text: string): this {
+    const existing = this.sections.findIndex((s) => s.kind === "head");
+    if (existing !== -1) {
+      this.sections[existing] = { kind: "head", content: text };
+    } else {
+      this.sections.push({ kind: "head", content: text });
+    }
+    return this;
+  }
+
+  context(text: string): this {
+    this.sections.push({ kind: "context", content: text });
+    return this;
+  }
+
+  prompt(text: string): this {
+    const existing = this.sections.findIndex((s) => s.kind === "prompt");
+    if (existing !== -1) {
+      this.sections[existing] = { kind: "prompt", content: text };
+    } else {
+      this.sections.push({ kind: "prompt", content: text });
+    }
+    return this;
+  }
+
+  guide(text: string): this {
+    this.sections.push({ kind: "guide", content: text });
+    return this;
+  }
+
+  warn(text: string): this {
+    this.sections.push({ kind: "warn", content: text });
+    return this;
+  }
+
+  build(): string {
+    const order: SectionKind[] = ["head", "context", "prompt", "guide", "warn"];
+    const groups: string[][] = order.map(() => []);
+
+    for (const section of this.sections) {
+      if (section.content.trim() === "") continue;
+      const idx = order.indexOf(section.kind);
+      if (idx !== -1) {
+        groups[idx].push(section.content);
+      }
+    }
+
+    const rendered: string[] = [];
+    for (const group of groups) {
+      if (group.length > 0) {
+        rendered.push(group.join("\n\n"));
+      }
+    }
+
+    return rendered.join("\n\n");
+  }
+}

tests/core/prompt-builder.test.ts

@@ -0,0 +1,78 @@
+import { describe, it, expect } from "bun:test";
+import { PromptBuilder } from "../../src/core/prompt-builder";
+
+describe("PromptBuilder", () => {
+  it("空 builder build 返回空字符串", () => {
+    const builder = new PromptBuilder();
+    expect(builder.build()).toBe("");
+  });
+
+  it("单段输出", () => {
+    const result = new PromptBuilder().head("# 标题").build();
+    expect(result).toBe("# 标题");
+  });
+
+  it("多段按序渲染", () => {
+    const result = new PromptBuilder()
+      .head("# 阶段")
+      .context("状态信息")
+      .prompt("核心引导")
+      .guide("操作指令")
+      .warn("警告信息")
+      .build();
+
+    const headPos = result.indexOf("# 阶段");
+    const contextPos = result.indexOf("状态信息");
+    const promptPos = result.indexOf("核心引导");
+    const guidePos = result.indexOf("操作指令");
+    const warnPos = result.indexOf("警告信息");
+
+    expect(headPos).toBeLessThan(contextPos);
+    expect(contextPos).toBeLessThan(promptPos);
+    expect(promptPos).toBeLessThan(guidePos);
+    expect(guidePos).toBeLessThan(warnPos);
+  });
+
+  it("空段跳过", () => {
+    const result = new PromptBuilder().head("# 标题").prompt("内容").guide("指引").build();
+    expect(result).toContain("# 标题");
+    expect(result).toContain("内容");
+    expect(result).toContain("指引");
+  });
+
+  it("同 kind 多次追加拼接", () => {
+    const result = new PromptBuilder()
+      .head("# 阶段")
+      .context("信息一")
+      .context("信息二")
+      .prompt("prompt")
+      .build();
+    expect(result).toContain("信息一\n\n信息二");
+  });
+
+  it("head 重复设值覆盖", () => {
+    const result = new PromptBuilder().head("# 旧标题").head("# 新标题").build();
+    expect(result).toBe("# 新标题");
+    expect(result).not.toContain("旧标题");
+  });
+
+  it("prompt 重复设值覆盖", () => {
+    const result = new PromptBuilder().prompt("旧 prompt").prompt("新 prompt").build();
+    expect(result).toContain("新 prompt");
+    expect(result).not.toContain("旧 prompt");
+  });
+
+  it("空字符串段被跳过", () => {
+    const result = new PromptBuilder().head("# 标题").context("").prompt("内容").build();
+    expect(result).toBe("# 标题\n\n内容");
+  });
+
+  it("链式调用返回 this", () => {
+    const builder = new PromptBuilder();
+    expect(builder.head("x")).toBe(builder);
+    expect(builder.context("x")).toBe(builder);
+    expect(builder.prompt("x")).toBe(builder);
+    expect(builder.guide("x")).toBe(builder);
+    expect(builder.warn("x")).toBe(builder);
+  });
+});