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amitray007amitray007/headroom/.agents/skills/app-api-compatibility/SKILL.md

app-api-compatibility

Skill83 starsChanged 11 days agoMITView on GitHub

Keep every supported Headroom for Mac release working with every supported server. Use before changing the Mac app API (`packages/view-model/src/app-feed.ts`, `apps/server/src/routes/app.ts`, `scripts/app-contract.ts`), Mac code that reads a server, the minimum server version, or the oldest supported Mac release.

The file

We split this skill into the rules it gives an agent

3 rules. About 0 are common, 2 are distinctive, and 1 is very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈2

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 1

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Add fields and endpoints. Keep every field a released Mac requires, at its type and as always sent.

    line 17
  2. Very specific:

    Run mise run mac:contract and commit apps/macos/Contract/openapi.json.

    line 20
  3. Distinctive:

    Read a new field as optional, and leave the feature out when it is absent.

    line 24

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

App API compatibility

A server and a Mac app ship separately, so any pairing of a supported server and a supported Mac release must work. The rules hold in two directions:

  • Old Macs, new server. Each macos-vX.Y.Z tag holds the contract that release decodes with. mise run mac:compat checks today's server against every tagged release from oldestSupportedMac in apps/macos/Contract/compatibility.json onward.
  • New Mac, old server. ServerCompatibility.minimumServer in HeadroomKit names the oldest server this build reads. Tests/HeadroomKitTests/Fixtures/Servers/<minimum>.json is that server's feed, frozen.

The app never refuses a server by its version number. A server built from main reports the last release while it already has newer endpoints. The app decides from what the server answers and uses versions only in messages: a missing endpoint or a missing field asks for a server update, and a value or type it does not know asks for an app update. The decision record is D47.

Server change: keep /api/app/v1 additive

  1. Add fields and endpoints. Keep every field a released Mac requires, at its type and as always sent. Keep every request a released Mac makes accepted.
  2. For a field whose values grow with the server, such as providers, list it in openEnumFields in scripts/app-contract.ts. Then the app decodes it as a plain string and shows an unknown value plainly. Values added to a closed enum break each Mac release that knows the old list. The check flags them.
  3. For a change that cannot be additive, add /api/app/v2 beside v1. Keep v1 until oldestSupportedMac passes every release that reads it.
  4. Run mise run mac:contract and commit apps/macos/Contract/openapi.json.

Mac change: read what the minimum server sends

  1. Read a new field as optional, and leave the feature out when it is absent. Treat a 404 from a new endpoint the same way. The rest of the source keeps reading.
  2. When a feature cannot work without the new field or endpoint, raise ServerCompatibility.minimumServer to the first server release that has it. That server release ships first. Replace the frozen feed in Fixtures/Servers/ with one from that release. A feed regenerated from today's server would hide a broken older one.
  3. Say "Needs server X.Y.Z or later" in the Mac release notes when the minimum rises.

Dropping old Macs

Raise oldestSupportedMac in apps/macos/Contract/compatibility.json only when the owner agrees to stop supporting those releases.

Done when

  • mise run check passes. It includes mac:contract:check and mac:compat.
  • mise run mac:test passes, including the frozen feed test.
  • The minimum server and the oldest supported Mac match in three places: ServerCompatibility, compatibility.json, and the tables in the Mac app architecture and the install guide.

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