LAYER 06 · Build and ship extensions

Lab: from plugins to a shippable product

Use packages, bundles, profiles, contract tests, and source snapshots to turn extensions into a maintainable product

20 min3 source anchorsupstream@47f9438
package → bundle → profile → release
The question this chapter resolves

What boundaries separate a locally working plugin from a shippable product?

Build intuition

Inventing a part is not shipping a product. You still need specifications, assembly manifests, compatible versions, acceptance tests, upgrade notes, and a recall path.

MECHANISM

Mechanism

Features separate Service Definition, provider, consumer, and policy packages. Bundles provide patchable config, profiles name product compositions, and user patches preserve local differences.

Developer preview means breaking change is normal. Teaching and extension projects should pin an upstream commit, keep a source map, use contract tests, and audit diffs regularly.

Step 1 of 6

Define package boundary

Export stable vocabulary and avoid reverse dependencies.

INVARIANTS

What extensions must preserve

  • Product defaults are explainable with --dump-config
  • User customization survives as upper-layer patches
  • Teaching claims name the upstream snapshot and inference boundary
FAILURE MODES

The tempting wrong turns

  • ×Hardcoding example config into providers
  • ×Publishing a bundle that requires source edits
  • ×Showing stale event ordering after upstream breaking changes
VERIFY IN SOURCE

Do not trust the conclusion—verify it

These anchors are pinned to official deepseek-harness@47f9438; account for later breaking changes when reading current upstream.

KNOWLEDGE CHECK

Pause for ten seconds before revealing

Why must this learning project record an upstream commit instead of saying latest?

Why the next chapter follows

You now have an end-to-end path from mental model and composition through runtime, safety, durability, and extension delivery. Keep the architecture atlas and source index as daily references.

Learn DeepSeek Harness

An independent learning project. Explanations derive from source; upstream remains authoritative.