atproto_lexicon/diff

Semantic diff over two LexiconDocs (old vs new), classifying every change as breaking or non-breaking for consumers of records written under the old schema. This is the substrate for the drift gate: diff says what changed and where, severity says whether it breaks, describe renders a one-line summary for CI output.

Types

Change

One semantic change, located by a mechanical path into the document, e.g. ["main", "record", "properties", "title"].

pub type Change {
  Change(path: List(String), kind: ChangeKind)
}

Constructors

Change(path: List(String), kind: ChangeKind)

ChangeKind

pub type ChangeKind {
  DocAdded
  DocRemoved
  DuplicateDocId(id: String)
  IdChanged(old: String, new: String)
  RevisionChanged(
    old: option.Option(Int),
    new: option.Option(Int),
  )
  DescriptionChanged
  DefAdded
  DefRemoved
  DefTypeChanged(old: String, new: String)
  RecordKeyChanged(old: String, new: String)
  FieldAdded
  RequiredFieldAdded
  FieldRemoved
  FieldMadeRequired
  FieldMadeOptional
  FieldMadeNullable
  FieldMadeNonNullable
  TypeChanged(old: String, new: String)
  UnionVariantRemoved(ref: String)
  UnionVariantAddedOpen(ref: String)
  UnionVariantAddedClosed(ref: String)
  UnionClosed
  UnionOpened
  EnumAdded
  EnumRemoved
  EnumValueRemoved(value: String)
  EnumValueAdded(value: String)
  ConstAdded
  ConstChanged
  ConstRemoved
  ConstraintTightened(constraint: String)
  ConstraintLoosened(constraint: String)
  FormatChanged(old: String, new: String)
  AcceptNarrowed(value: String)
  AcceptWidened(value: String)
  KnownValuesChanged
  DefaultChanged
  EncodingChanged(old: String, new: String)
  BodyAdded
  BodyRemoved
  SchemaAdded
  SchemaRemoved
  ErrorAdded
  ErrorRemoved
}

Constructors

```
DocAdded
```
```
DocRemoved
```
```
DuplicateDocId(id: String)
```
```
IdChanged(old: String, new: String)
```

RevisionChanged(old: option.Option(Int), new: option.Option(Int))

```
DescriptionChanged
```
```
DefAdded
```
```
DefRemoved
```

DefTypeChanged(old: String, new: String)

RecordKeyChanged(old: String, new: String)

```
FieldAdded
```
```
RequiredFieldAdded
```
```
FieldRemoved
```
```
FieldMadeRequired
```
```
FieldMadeOptional
```
```
FieldMadeNullable
```
```
FieldMadeNonNullable
```
```
TypeChanged(old: String, new: String)
```
```
UnionVariantRemoved(ref: String)
```
```
UnionVariantAddedOpen(ref: String)
```
```
UnionVariantAddedClosed(ref: String)
```
```
UnionClosed
```
```
UnionOpened
```
```
EnumAdded
```
```
EnumRemoved
```
```
EnumValueRemoved(value: String)
```
```
EnumValueAdded(value: String)
```
```
ConstAdded
```
```
ConstChanged
```
```
ConstRemoved
```
```
ConstraintTightened(constraint: String)
```
```
ConstraintLoosened(constraint: String)
```
```
FormatChanged(old: String, new: String)
```
```
AcceptNarrowed(value: String)
```
```
AcceptWidened(value: String)
```
```
KnownValuesChanged
```
```
DefaultChanged
```

EncodingChanged(old: String, new: String)

```
BodyAdded
```
```
BodyRemoved
```
```
SchemaAdded
```
```
SchemaRemoved
```
```
ErrorAdded
```
```
ErrorRemoved
```

Severity

pub type Severity {
  Breaking
  NonBreaking
}

Constructors

```
Breaking
```
```
NonBreaking
```

Values

describe

pub fn describe(change: Change) -> String

Render a change as a one-line summary for CI output.

diff

pub fn diff(
  old: ast.LexiconDoc,
  new: ast.LexiconDoc,
) -> List(Change)

Diff a single document pair, old vs new, under the same id.

diff_all

pub fn diff_all(
  old: List(ast.LexiconDoc),
  new: List(ast.LexiconDoc),
) -> List(Change)

Diff two sets of documents keyed by id; paths gain the doc id prefix. Duplicate ids within either input list are reported explicitly rather than silently collapsed; the rest of the diff then proceeds against the first occurrence of each id, matching split_keyed’s lookup semantics.

severity

pub fn severity(kind: ChangeKind) -> Severity

Whether a change breaks consumers of records written under the old schema.