[coryodaniel]

Implements the CLI side of massdriver-cloud/massdriver#3516. Backend validation and the provides API field land in the paired massdriver PR; docs in massdriver-cloud/docs#235.

New functionality

• provides: an optional top-level key listing what a bundle offers. runtime is the only accepted value; other values are deferred until their names are settled.
• provides lint (mass bundle lint / publish):
  • unknown or duplicate values fail
  • a bundle cannot both provide runtime and set app.runtime
• Runtimes and applications: an application sets app.runtime: <runtime>@<constraint>. build, lint, and publish resolve the newest matching runtime, pull it, check it, and merge the application onto it. The result publishes as an ordinary bundle.
• Runtime check after pull: before merging, the pulled parent must provide runtime, not set app.runtime itself, and use dependencies/resources rather than legacy connections/artifacts.
• Merge rules:
  • the runtime owns steps, params, ui, its resources, and the IaC
  • the application may set name, version (required, semver), description, source_url, schema, provides, dependencies, resources, steps, and app (runtime, envs, secrets only); name, description, source_url, and schema must be strings; any other key, including a null like params:, fails the build
  • application dependencies, app.envs, app.secrets, and resources are added to the runtime's; any name collision fails
  • the merged bundle carries the application's provides, never the runtime's
  • app.envs must reference params and dependencies in the merged bundle; reading an optional dependency warns
  • README.md, CHANGELOG.md, icon.svg, operator.md from the application replace the runtime's
• Resources emitted by applications: an application declares resources and binds each to a runtime step with a jq template at steps[].resources.<name>.template. Templates stay in the published massdriver.yaml for the backend to render after the step applies.
• Pinned runtime: the published massdriver.yaml pins app.runtime to the exact runtime version it was built on, e.g. lambda@~1.2 becomes lambda@1.2.7.
• Build directory: build assembles into <application>/.massdriver/build/ (git-ignored); lint and publish use a temp dir. Bundles without app.runtime are untouched.
• publish returns errors on lint failure instead of os.Exit(1), so the temp build directory is cleaned up.

Examples

A runtime:

name: lambda
version: 1.2.7
provides: [runtime]

app:
  envs:
    LOG_LEVEL: .params.log_level

An application that runs on it and emits its own resource:

name: billing-api
version: 0.1.0

dependencies:
  db:
    resource_type: postgres@~1
    required: true

resources:
  billing:
    resource_type: billing-api@1.0.0
    required: true

steps:
  - path: src
    resources:
      billing:
        template: |
          { url: .outputs.function_url, region: .params.region }

app:
  runtime: lambda@~1.2
  envs:
    DB_HOST: .dependencies.db.host
  secrets:
    STRIPE_KEY:
      required: true

$ mass bundle publish --development
Using runtime lambda@1.2.7 (~1.2, sha256:...)
...
 ✓ Provides check passed.

Published app.runtime:

app:
  runtime: lambda@1.2.7

Rejected:

$ mass bundle build   # app.runtime points at a bundle without provides: [runtime]
Error: lambda@1.2.7 does not provide a runtime. Add `runtime` to `provides` in its massdriver.yaml and republish

$ mass bundle lint    # provides: [compute]
provides: 'compute' is not one of runtime

$ mass bundle build   # application step sets more than resources
Error: a step in a bundle with 'app.runtime' may only set path and resources; remove: provisioner

Notes

• The runtime is resolved with Bundles.Get("name@constraint"), the same resolver deploys use, rather than ociRepo.releaseChannels: the dev-channel SQL there orders version_pre_release ASC, so ~X+dev channels point at the oldest dev build.

🤖 Generated with Claude Code

[coryodaniel]

Extending shouldn't be the 'default' docs explanation. Include a regular build/publish example and we'll put the extending in docs.massdriver.cloud.