Why This Matters

This capstone builds a production prompt-library service — the foundation of Prompt Ops. Combines prompting (Phase 2) with platform engineering (Phase 3).

Concept Explained

Prompt-library service: versioned prompts, API for consumption, eval hooks (every prompt tested), dashboard for management.

How It Works

Build service: CRUD for prompts (with versioning), API for consumption (apps fetch latest), eval hooks (run eval on every change), dashboard (manage prompts, see eval results).

Step-by-Step Tutorial

1. Define schema

2. Build CRUD

3. Build API

4. Add eval hooks

5. Build dashboard

6. Deploy

Real-World Example

A team built this service. 100 prompts, versioned. Every change ran eval automatically. Caught 5 regressions before prompts went to production. Prompt Ops became a discipline.

Example Prompts / Commands / Code

"""[Web Dashboard]
   |
   v
[Prompt Library Service]
   |           |
   v           v
[Versioned Storage]  [Eval Runner]
   |                       |
   v                       v
[API for Consumption]  [Eval Results DB]

- Prompts versioned (v1, v2, v3...)
- API: GET /prompts/{id}/latest
- Eval: on prompt change, run golden set
- Dashboard: manage prompts, view eval
"""

"""Prompt:
  id: string (slug)
  version: int
  content: string (with {{placeholders}})
  placeholders: string[]
  metadata:
    author: string
    created_at: datetime
    description: string
    tags: string[]
  eval_results:
    - version: int
    - score: float
    - run_at: datetime
    - regressions: bool

API:
  GET /prompts                    # list all
  GET /prompts/{id}               # get latest
  GET /prompts/{id}/versions      # list versions
  POST /prompts                   # create
  PUT /prompts/{id}               # new version
  DELETE /prompts/{id}            # delete (soft)

  POST /prompts/{id}/eval         # run eval manually
"""

Common Mistakes

• No versioning — can't roll back regressions.
• No eval hooks — regressions slip in.
• No API — apps hardcode prompts.
• No dashboard — manual management burden.

Best Practices

• Version every prompt (immutable history).
• Eval on every change (golden set).
• API for consumption (apps fetch latest).
• Dashboard for management.
• Allow rollback to any version.

Troubleshooting

Practical Exercise

Professional Challenge

Frequently Asked Questions

Further Reading

• Prompt engineering

Official References

• Prompt engineering

Related lessons: IN-06, IN-47, PR-52