feat: add author skill — workflow YAML design guide

Adds 'uwf skill author' for agents/humans designing workflow definitions.
Covers: YAML structure, role definition, frontmatter schema design,
graph routing, edge prompts, self-testing, and common pitfalls.

Refs #539

packages/cli-workflow/src/__tests__/skill.test.ts

@@ -8,6 +8,7 @@ const __dirname = dirname(fileURLToPath(import.meta.url));
 import {
   cmdSkillActor,
   cmdSkillArchitecture,
+  cmdSkillAuthor,
   cmdSkillCli,
   cmdSkillList,
   cmdSkillModerator,
@@ -25,6 +26,7 @@ describe("skill commands", () => {
     expect(result).toContain("moderator");
     expect(result).toContain("actor");
     expect(result).toContain("user");
+    expect(result).toContain("author");
     for (const name of result) {
       expect(name).toMatch(/^\S+$/);
     }
@@ -84,6 +86,17 @@ describe("skill commands", () => {
     expect(result.length).toBeGreaterThan(500);
   });
 
+  test("skill author returns non-empty markdown string", () => {
+    const result = cmdSkillAuthor();
+    expect(typeof result).toBe("string");
+    expect(result).toContain("frontmatter");
+    expect(result).toContain("graph");
+    expect(result).toContain("$START");
+    expect(result).toContain("$END");
+    expect(result).toContain("$status");
+    expect(result.length).toBeGreaterThan(500);
+  });
+
   test("skill help subcommand is suppressed", () => {
     const output = execFileSync("bun", ["src/cli.ts", "skill", "--help"], {
       cwd: join(__dirname, "..", ".."),
@@ -97,6 +110,7 @@ describe("skill commands", () => {
     expect(output).toContain("moderator");
     expect(output).toContain("actor");
     expect(output).toContain("user");
+    expect(output).toContain("author");
     expect(output).toContain("list");
   });
 });

packages/cli-workflow/src/cli.ts

@@ -19,6 +19,7 @@ import { cmdSetup, cmdSetupInteractive } from "./commands/setup.js";
 import {
   cmdSkillActor,
   cmdSkillArchitecture,
+  cmdSkillAuthor,
   cmdSkillCli,
   cmdSkillList,
   cmdSkillModerator,
@@ -512,6 +513,13 @@ skill
     console.log(cmdSkillActor());
   });
 
+skill
+  .command("author")
+  .description("Print the author reference (workflow YAML design guide)")
+  .action(() => {
+    console.log(cmdSkillAuthor());
+  });
+
 skill
   .command("moderator")
   .description("Print the moderator reference")

packages/cli-workflow/src/commands/skill.ts

@@ -1,13 +1,22 @@
 export {
   generateActorReference as cmdSkillActor,
   generateArchitectureReference as cmdSkillArchitecture,
+  generateAuthorReference as cmdSkillAuthor,
   generateCliReference as cmdSkillCli,
   generateModeratorReference as cmdSkillModerator,
   generateUserReference as cmdSkillUser,
   generateYamlReference as cmdSkillYaml,
 } from "@uncaged/workflow-util";
 
-const SKILL_NAMES = ["cli", "architecture", "yaml", "moderator", "actor", "user"] as const;
+const SKILL_NAMES = [
+  "cli",
+  "architecture",
+  "yaml",
+  "moderator",
+  "actor",
+  "user",
+  "author",
+] as const;
 
 export function cmdSkillList(): ReadonlyArray<string> {
   return [...SKILL_NAMES];

packages/workflow-util/src/author-reference.ts

@@ -0,0 +1,183 @@
+export function generateAuthorReference(): string {
+  return `# Author Reference
+
+Guide for designing and writing workflow YAML definitions.
+
+## Workflow Structure
+
+\`\`\`yaml
+name: solve-issue              # verb-first kebab-case
+description: "..."             # human-readable summary
+
+roles:                         # named actors
+  planner:
+    description: "..."         # short purpose
+    goal: "..."                # system-level goal for the agent
+    capabilities: [...]        # skill keywords the agent should load
+    procedure: |               # step-by-step instructions
+      1. Do this
+      2. Do that
+    output: "..."              # what the agent should produce
+    frontmatter:               # JSON Schema for structured output
+      oneOf:
+        - properties:
+            $status: { const: "ready" }
+            plan: { type: string }
+          required: [$status, plan]
+        - properties:
+            $status: { const: "failed" }
+            error: { type: string }
+          required: [$status, error]
+
+graph:                         # status-based routing
+  $START:
+    _: { role: planner, prompt: "Analyze the issue." }
+  planner:
+    ready: { role: developer, prompt: "Implement {{{plan}}}." }
+    failed: { role: $END, prompt: "Failed: {{{error}}}" }
+\`\`\`
+
+## Role Definition
+
+| Field | Purpose |
+|-------|---------|
+| \`description\` | Short description for humans and moderator context |
+| \`goal\` | Injected as the agent's system-level objective |
+| \`capabilities\` | Keyword tags — agent loads matching skills before starting |
+| \`procedure\` | Step-by-step instructions the agent follows |
+| \`output\` | Describes what to produce and which \`$status\` values to use |
+| \`frontmatter\` | JSON Schema defining the structured output fields |
+
+### Role Design Principles
+
+- **Single responsibility** — each role does one thing well
+- **Minimal context** — don't overload a role with too many steps; split if needed
+- **Clear status values** — each status should map to a distinct graph edge
+- **Explicit output** — tell the agent exactly what \`$status\` values are valid
+
+## Frontmatter Schema
+
+The \`frontmatter\` field is a standard JSON Schema. It defines the structured fields the agent must output in YAML frontmatter.
+
+### \`$status\` Field
+
+\`$status\` is the only standard field. Its value determines which graph edge the moderator follows. Use \`const\` to constrain each variant:
+
+\`\`\`yaml
+frontmatter:
+  oneOf:
+    - properties:
+        $status: { const: "done" }
+        result: { type: string }
+      required: [$status, result]
+    - properties:
+        $status: { const: "failed" }
+        error: { type: string }
+      required: [$status, error]
+\`\`\`
+
+### Custom Fields
+
+Add any fields you need for data passing between roles. These are available in edge prompts via Mustache templates.
+
+### Flat Schema (Single Status)
+
+When a role has only one outcome:
+
+\`\`\`yaml
+frontmatter:
+  properties:
+    $status: { const: "done" }
+    summary: { type: string }
+  required: [$status, summary]
+\`\`\`
+
+## Graph Routing
+
+The graph maps each role's \`$status\` values to the next role:
+
+\`\`\`
+graph[role][$status] → { role: nextRole, prompt: edgePrompt }
+\`\`\`
+
+### Special Nodes
+
+| Node | Purpose |
+|------|---------|
+| \`$START\` | Entry point — status key is always \`_\` (unconditional) |
+| \`$END\` | Terminal — thread completes and is archived |
+
+### Edge Prompts
+
+Use triple-brace Mustache (\`{{{field}}}\`) to pass data from the previous step's output:
+
+\`\`\`yaml
+graph:
+  planner:
+    ready: { role: developer, prompt: "Implement plan {{{plan}}} in {{{repoPath}}}." }
+\`\`\`
+
+The fields referenced must exist in the source role's frontmatter schema.
+
+### Loops and Branching
+
+Roles can route back to previous roles (loops) or to different roles based on status (branching):
+
+\`\`\`yaml
+graph:
+  reviewer:
+    approved: { role: tester, prompt: "Run tests." }
+    rejected: { role: developer, prompt: "Fix: {{{comments}}}" }  # loop back
+\`\`\`
+
+### Fail Routing
+
+Route failures to a cleanup role or \`$END\`:
+
+\`\`\`yaml
+graph:
+  developer:
+    done: { role: reviewer, prompt: "Review changes." }
+    failed: { role: cleanup, prompt: "Clean up: {{{error}}}" }
+\`\`\`
+
+## Self-Testing
+
+### Step-by-Step Verification
+
+\`\`\`bash
+# Start a thread directly from YAML file (no registration needed)
+uwf thread start my-workflow.yaml -p "Test prompt"
+
+# Or register first, then start by name
+uwf workflow add my-workflow.yaml
+uwf thread start my-workflow -p "Test prompt"
+
+# Execute one step at a time to verify routing
+uwf thread exec <thread-id>
+
+# Inspect step output
+uwf step list <thread-id>
+uwf step show <step-hash>
+
+# Check the CAS data
+uwf cas get <output-hash>
+\`\`\`
+
+### Validation Checklist
+
+1. Every \`$status\` value in a role's frontmatter has a matching edge in the graph
+2. Every field referenced in edge prompts (\`{{{field}}}\`) exists in the source role's schema
+3. Every role referenced in the graph exists in \`roles\`
+4. \`$START\` has exactly one edge with key \`_\`
+5. At least one path leads to \`$END\`
+6. No orphan roles (defined but never routed to)
+
+## Common Pitfalls
+
+- **Missing graph edge** — if a role can produce \`$status: failed\` but the graph has no \`failed\` edge, the moderator will error
+- **Mustache field mismatch** — referencing \`{{{branch}}}\` in an edge prompt but the source schema has \`branchName\` instead
+- **Overly complex roles** — a role with 20 steps should be split; each role should be completable in one agent turn
+- **No fail path** — always handle failure; route to cleanup or \`$END\`
+`;
+}

packages/workflow-util/src/index.ts

@@ -1,5 +1,6 @@
 export { generateActorReference } from "./actor-reference.js";
 export { generateArchitectureReference } from "./architecture-reference.js";
+export { generateAuthorReference } from "./author-reference.js";
 export { encodeUint64AsCrockford } from "./base32.js";
 export { generateCliReference } from "./cli-reference.js";
 export { env } from "./env.js";