Day 94: Change Management for Prompts

Hot-editing the system prompt in a Lambda env var is how you ship an incident without a diff. Prompts are code: version, review, eval, pin.

⚡ TL;DR: Store prompts in Bedrock Prompt Management or git. Pin versions in the gateway. Promote with CI eval gates. No console edits in prod.

Change flow

PR (prompt + eval delta) → CI eval → stage pin → prod pin → monitor

# ✅ Gateway resolves pin, not "latest"
def resolve_prompt(prompt_id: str, env: str) -> tuple[str, str]:
    pin = registry.get_pin(prompt_id, env)  # e.g. "v12"
    body = registry.fetch(prompt_id, pin)
    return pin, body

❌ PROMPT=$(curl raw.githubusercontent.com/.../main/...) at runtime.

Failure modes

Two gateways pinning different versions after a partial deploy. Pin config in a single store with atomic swaps. “Emergency” console edits without a follow-up PR — detect drift jobs that diff live vs git.

Closing checklist

• [ ] Prompt registry with versions
• [ ] Gateway pins per env
• [ ] CI eval on prompt PRs
• [ ] Console write access removed in prod
• [ ] Rollback runbook = previous pin

Series navigation

Day 93: SLOs for AI Features · Day 95: Incident Response When the Agent Goes Wrong

Last updated September 11, 2026