[tmm]

Moves the Swift code generator out of packages/zero-swift-cli into a new npm package, zerogen (packages/zerogen), with its own semver. Rust comes later.

zerogen

• zerogen codegen generates every target in zerogen.json, or the one --target swift|rust names. Only Swift is implemented. --target rust, a rust entry in the config, or no target at all fail with UNSUPPORTED_TARGET / NO_TARGETS before anything is written.
• zerogen drift record is the same target-independent recorder as before.
• Shared, in cli.ts / types.ts / drift.ts: schema loading, the type model, the incur commands, output and --check, and the drift recorder. Per language, in targets/swift.ts: naming, escaping, SDK and type mappings, and the Swift options (--schema-name, --zql, --type-prefix, --access). generate.ts moved there unchanged apart from taking its options.
• zerogen.json has the shared schema and export, and targets.swift takes the rest of zero-swift.json's keys.

zero-swift stays published and is not deprecated. It's now a 5-line wrapper over zerogen/compat, and depends on zerogen with workspace:*, which pnpm pack turns into the exact version. Its config, legacy flags (--schema <path>, --typePrefix=…), results, and output don't change, and the generated banner still says zero-swift codegen.

Releases. swift-release.yml versions and publishes zerogen alongside the Swift client:

• It publishes zerogen before zero-swift, in the same approved swift-release job. If zerogen fails to publish, zero-swift isn't published.
• Before publishing, it smoke-tests the packed tarballs and checks that the packed zero-swift depends on exactly the zerogen being released.
• A version counts as unpublished only on a registry 404. zero-swift's old npm view check counted any error that way.
• Nothing is published by merging this: the changesets go into the Version Packages PR first.

Verified

Check	Result
pnpm --filter zerogen --filter zero-swift test	2 + 29 passed. These include the byte-for-byte fixture and zbugs checks against the checked-in Swift and drift-vectors.json, and the Swift compile sweep (Swift 6.2.4, Linux).
Parity with zero-swift@0.7.9 from npm vs. the new packed tarballs, both on @rocicorp/zero@1.11.0	31 cases identical in stdout, stderr and exit code, and 5 generated files identical. Cases cover --help, codegen --help, --llms, bare --schema, legacy and kebab flags, --json, --check (fresh and stale), every error code, drift record and its --check, and --target (still rejected by the wrapper).
pnpm --filter zerogen smoke	Passed: installs both tarballs outside the workspace and runs both CLIs.
check-types (zero-conformance, zerogen, zero-swift), syncpack lint, oxlint, oxfmt	Clean.
actionlint 1.7.7 with ShellCheck	Only a pre-existing SC2016 info that main also reports.
Plan script vs. the live npm registry and mirror	With zero-swift already on npm: npm=false, zerogen-npm=true, mirror=false. With an unreleased zero-swift and zerogen 0.1.0: all true.
Changesets dry run (rebased onto 0.7.10)	zerogen 0.0.0→0.1.0 and zero-swift 0.7.10→0.7.11 (swift/VERSION too).
pnpm install --frozen-lockfile	Passes, and leaves pnpm-lock.yaml byte-identical. The lockfile was edited by hand, with workspace links only.

Before releasing (tmm)

1. Set up npm for zerogen before merging the Version Packages PR. npm only adds a trusted publisher to a package that exists, so the first zerogen version has to be published by hand. The publisher to add is this repo, swift-release.yml, environment swift-release, allowed to npm publish. Until then the "Publish zerogen" step fails and blocks zero-swift; the Swift mirror release still goes out. zerogen was unclaimed on npm (404) when this PR was opened.
2. Every zerogen release also bumps zero-swift by a patch, and with it swift/VERSION, so the Swift mirror is released too. Changesets reads workspace:* as the exact old version; a dry run confirmed that a zerogen-only patch also bumps zero-swift by a patch. Splitting the wrapper's version from swift/VERSION would avoid this, but that's a separate change.

Not run locally: the full swift/ and zbugs swift test suites and macOS CI. No Swift sources, generated Swift, or vectors change; CI runs them.

Started in a thread that stopped on a model usage limit (https://ampcode.com/threads/T-98d49fb9-9997-4a89-ae8f-8810e2d2175d) and finished here.