[sethjuarez]

What & why

Add the stock TypeSpec spelling x: T | null = null for legacy input that omits a key which canonical output must always write.

Declaration	Missing key on load	Unset value on save
`x: T	null`	Reject
`x: T	null = null`	Load as null
x?: T or `x?: T	null`	Accept

Swift and Swift/Codable unknown-discriminator carriers also fill absent inherited null-default keys on save while preserving non-null values and unknown payload fields. Required nullable fields without defaults still reject absence.

The authorized release batch also repairs shared enum declarations in Go/Rust/Swift, nullable alias names across targets, and C# Record<string> loads that failed with CS8602. Null string-record entries now report their key path instead of dereferencing null.

Fixes #346.

Reproduction-first checklist

Typra fixes codegen bugs by turning the reproduction into a permanent test. For any change to emitter
behavior or generated output, confirm:

• A focused feature fixture carries the shape (packages/typra-emitter/fixtures/features/<area>/main.tsp), or an existing one was extended.
• A test asserts the fix — a validate-fixtures.mjs assertion, a golden under generated/fixtures/<lang>, and/or a unit test that fails on main and passes here.
• Where behavior is runtime-observable, an executable @vector/@sample encodes input → expected/expectedError.
• npm test, npm run validate:fixtures, and npm run lint pass.
• The PR title is a Conventional Commit (type(scope): summary) — it becomes the squash commit and the CHANGELOG entry release-please generates.

Notes

Commands below ran in packages/typra-emitter unless stated otherwise.

• npm test: passed, 931 tests, 0 failures, 0 skipped, exit 0.
• npm run lint: passed, exit 0.
• npm run validate:fixtures: complete rerun passed at 113dc4a, exit 0. All generated-test and executable-conformance stages completed; only the seven declared formatter-idempotency stages below were deferred.
• npm run pack:dry-run (repository root): passed, exit 0.
• Native C# build reproduced two CS8602 errors before repair. Generated C# build and executable conformance pass afterward, including null-entry rejection with key paths.
• The exact Python: inline literal alias named after its field breaks import (mood: mood | None) #346 spec imports and round-trips calm, busy, and null in Python and Pydantic. Permanent nullable fixture tests also cover a nested alias.
• Native Swift and Swift/Codable unknown-kind regressions failed before the repair and passed afterward on Swift 6.3.3 for Windows.

The earlier Windows gofmt failures came from CRLF checkouts of two unchanged Go adapters. Normalizing those working copies to their indexed LF content removed the failures without a Git diff. No fixture line-ending change is included in the commits. The first full run found a stale nullable IR golden for the new Combo field; 113dc4a corrects it and the complete rerun passes.

Known limitations

• Rust: single polymorphic reference fields skip defaults on load and save #345 remains open: Rust single polymorphic references are raw JSON and do not materialize nested defaults. Direct model loading and typed polymorphic collections apply the defaults. This representation is unchanged.
• Seven formatter-idempotency stages remain explicitly deferred under Add a formatter-idempotency guard so native output is byte-stable regardless of host tooling #238: Java, Java/Jackson, Rust, Rust/serde, Swift, Swift/Codable, and TypeScript/zod. They are not reported as passes.

BREAKING CHANGE: nullable literal aliases now use their declared type name (for example Mood, not the property-derived mood). Update direct references to old generated symbols when regenerating 3.0.0 output. Rust shared enum declarations may move between model source modules; use the unchanged generated module re-exports rather than an owner-file-specific import.