vs raw AGENTS.md
A prompt file isn’t a permissions boundary, an engine pin, or a versioned identity. An Agent Pack is the prompt plus the contract that makes it shippable.
The missing production unit
A versioned, deployable unit of agent — its prompt, its tools, its engine, and its permissions.
What your IDE writes, your CI validates, and your infrastructure runs — small enough to review and roll back, portable across engines and your perimeter.
# yaml-language-server: $schema=https://packs.agenthippo.ai/schema/v1/agent.json apiVersion: agenthippo.ai/v1 kind: Agent metadata: name: warehouse-analyst version: 0.1.0 spec: engine: claude engineVersion: 2.1.209 model: claude-fable-5 permissions: fileAccess: read-only
Line 1 names the format. Everything else is reviewable like any other production change.
Author the pack in an IDE — prompt, tools, engine, permissions in one versioned unit.
Schema-check in CI. Reject drift before it reaches production data.
Deploy into your infrastructure — or point spec.remote at the instance that serves it.
Agents that can’t leave the laptop without becoming a liability — no version, no permissions boundary, no audit trail — so pilots die.
A prompt in a chat tab or a pile of scripts. Works on one machine, unreviewsable in git, no shared contract.
Once two people use it on company data, nobody can answer whose permissions ran, or which version touched production.
Whatever you prototyped on becomes welded into code — switching engines means a rewrite, so you never measure.
Most teams don’t choose an engine. They inherit whichever one they prototyped with — because revisiting the choice has always meant a rewrite.
In an Agent Pack, spec.engine is a manifest field. Same prompt, same tools, same permissions — change one line and re-run your evals.
metadata: version: 0.1.0 version: 0.3.0 spec: engine: claude model: claude-fable-5 engine: codex model: gpt-5.4
Hours to find out which engine wins on your workload — versus a redesign. See also multi-engine IDE.
Landmarks for how people build agents today.
A prompt file isn’t a permissions boundary, an engine pin, or a versioned identity. An Agent Pack is the prompt plus the contract that makes it shippable.
Hosted agent clouds usually mean their container and roster.
A Pack deploys into your perimeter; optional spec.remote points at that instance.
Welding to one provider’s SDK makes every model release a migration. A manifest field lets you re-benchmark and bump a version.
The published specification is CC BY 4.0. The registry, certification, and runtime are separate products.