feat(cli): help --skill <topic> — context-specific docs for agents

- help --skill (no args) → lists available topics
- help --skill cli → full CLI reference (was: help --skill)
- help --skill develop → thread ID, CAS, meta output guide for roles
- help --skill author → bundle structure, descriptor, role definition
- Role prompts updated: planner/coder reference 'help --skill develop'
- Legacy formatSkillDoc() preserved for compat
- 234 tests (15 new), build clean

Closes #81

小橘 🍊

packages/cli-workflow/__tests__/help.test.ts

@@ -1,6 +1,11 @@
 import { describe, expect, test } from "bun:test";
 import { runCli } from "../src/cli-dispatch.js";
-import { formatSkillDoc } from "../src/cmd-help.js";
+import {
+  formatSkillDoc,
+  formatSkillIndex,
+  formatSkillTopic,
+  getSkillTopics,
+} from "../src/cmd-help.js";
 
 const STORAGE_ROOT = "/tmp/help-test-storage";
 
@@ -10,13 +15,53 @@ describe("help command", () => {
     expect(code).toBe(0);
   });
 
-  test("help --skill returns 0", async () => {
+  test("help --skill (no topic) returns 0 and lists topics", async () => {
     const code = await runCli(STORAGE_ROOT, ["help", "--skill"]);
     expect(code).toBe(0);
   });
+
+  test("help --skill cli returns 0", async () => {
+    const code = await runCli(STORAGE_ROOT, ["help", "--skill", "cli"]);
+    expect(code).toBe(0);
+  });
+
+  test("help --skill develop returns 0", async () => {
+    const code = await runCli(STORAGE_ROOT, ["help", "--skill", "develop"]);
+    expect(code).toBe(0);
+  });
+
+  test("help --skill author returns 0", async () => {
+    const code = await runCli(STORAGE_ROOT, ["help", "--skill", "author"]);
+    expect(code).toBe(0);
+  });
+
+  test("help --skill unknown returns 1", async () => {
+    const code = await runCli(STORAGE_ROOT, ["help", "--skill", "unknown"]);
+    expect(code).toBe(1);
+  });
 });
 
-describe("formatSkillDoc", () => {
+describe("getSkillTopics", () => {
+  test("returns all topics", () => {
+    const topics = getSkillTopics();
+    const names = topics.map((t) => t.name);
+    expect(names).toContain("cli");
+    expect(names).toContain("develop");
+    expect(names).toContain("author");
+  });
+});
+
+describe("formatSkillIndex", () => {
+  test("lists all topics", () => {
+    const idx = formatSkillIndex();
+    expect(idx).toContain("cli");
+    expect(idx).toContain("develop");
+    expect(idx).toContain("author");
+    expect(idx).toContain("help --skill <topic>");
+  });
+});
+
+describe("formatSkillTopic('cli') — legacy formatSkillDoc", () => {
   const doc = formatSkillDoc();
 
   test("contains title", () => {
@@ -82,3 +127,52 @@ describe("formatSkillDoc", () => {
     expect(doc).toContain("## Typical Workflow");
   });
 });
+
+describe("formatSkillTopic('develop')", () => {
+  const doc = formatSkillTopic("develop");
+
+  test("returns non-null", () => {
+    expect(doc).not.toBeNull();
+  });
+
+  test("contains thread ID info", () => {
+    expect(doc).toContain("Thread ID");
+    expect(doc).toContain("Crockford Base32");
+  });
+
+  test("contains CAS commands", () => {
+    expect(doc).toContain("cas put");
+    expect(doc).toContain("cas get");
+  });
+
+  test("contains meta output section", () => {
+    expect(doc).toContain("Meta Output");
+  });
+});
+
+describe("formatSkillTopic('author')", () => {
+  const doc = formatSkillTopic("author");
+
+  test("returns non-null", () => {
+    expect(doc).not.toBeNull();
+  });
+
+  test("contains bundle structure", () => {
+    expect(doc).toContain("Bundle Structure");
+    expect(doc).toContain(".esm.js");
+  });
+
+  test("contains descriptor info", () => {
+    expect(doc).toContain("WorkflowDescriptor");
+  });
+
+  test("contains role definition", () => {
+    expect(doc).toContain("Role Definition");
+  });
+});
+
+describe("formatSkillTopic unknown", () => {
+  test("returns null for unknown topic", () => {
+    expect(formatSkillTopic("nonexistent")).toBeNull();
+  });
+});