Interface: SchemaRegistry

Defined in: src/Mnemonic/types.ts:619

Lookup and registration API for key schemas and migration paths.

Implementations of this interface are passed to MnemonicProvider via the schemaRegistry option. The provider calls these methods at read and write time to resolve the correct JSON Schema and migration chain for each stored value.

In "default" and "strict" modes, callers should treat registry contents as immutable after provider initialization. The hook caches lookups to keep read/write hot paths fast. "autoschema" remains mutable to support inferred schema registration.

Most applications should prefer createSchemaRegistry instead of implementing this interface manually. Manual implementations are mainly for advanced cases such as custom backing stores, dynamic schema discovery, or adapter layers around an existing registry system.

Example

const registry = createSchemaRegistry({
  schemas: [
    { key: "settings", version: 1, schema: { type: "object", required: ["theme"] } },
  ],
  migrations: [],
});

<MnemonicProvider namespace="app" schemaRegistry={registry} schemaMode="strict">
  <App />
</MnemonicProvider>

See

• KeySchema - Schema definition
• MigrationPath - Migration chain returned by getMigrationPath
• SchemaMode - How the provider uses the registry

Methods

getLatestSchema()

getLatestSchema(key): KeySchema<unknown, string, JsonSchema> | undefined

Defined in: src/Mnemonic/types.ts:638

Look up the highest-version schema registered for a key.

Used by the write path to determine which version to stamp on new values, and by the read path to detect when a migration is needed.

Parameters

Parameter	Type	Description
key	string	The unprefixed storage key

Returns

KeySchema<unknown, string, JsonSchema> | undefined

The latest schema, or undefined if none is registered

---

getMigrationPath()

getMigrationPath(key, fromVersion, toVersion): MigrationPath<string> | null

Defined in: src/Mnemonic/types.ts:652

Resolve an ordered migration path between two versions of a key.

Returns null when no contiguous path exists. The returned rules are applied in order to transform data from fromVersion to toVersion.

Parameters

Parameter	Type	Description
key	string	The unprefixed storage key
fromVersion	number	The stored data's current version
toVersion	number	The target version to migrate to

Returns

MigrationPath<string> | null

An ordered array of migration rules, or null

---

getSchema()

getSchema(key, version): KeySchema<unknown, string, JsonSchema> | undefined

Defined in: src/Mnemonic/types.ts:627

Look up the schema registered for a specific key and version.

Parameters

Parameter	Type	Description
key	string	The unprefixed storage key
version	number	The version number to look up

Returns

KeySchema<unknown, string, JsonSchema> | undefined

The matching schema, or undefined if none is registered

---

getWriteMigration()?

optional getWriteMigration(key, version): MigrationRule<unknown, unknown, string> | undefined

Defined in: src/Mnemonic/types.ts:669

Look up a write-time normalizer for a specific key and version.

A write-time normalizer is a MigrationRule where fromVersion === toVersion. It runs on every write to that version, transforming the value before storage. The normalized value is re-validated against the schema after transformation.

Optional. When not implemented or returns undefined, no write-time normalization is applied.

Parameters

Parameter	Type	Description
key	string	The unprefixed storage key
version	number	The target schema version

Returns

MigrationRule<unknown, unknown, string> | undefined

The normalizer rule, or undefined if none is registered

---

registerSchema()?

optional registerSchema(schema): void

Defined in: src/Mnemonic/types.ts:681

Register a new schema.

Optional. Required when schemaMode is "autoschema" so the library can persist inferred schemas. Implementations should throw if a schema already exists for the same key + version with a conflicting definition.

Parameters

Parameter	Type	Description
schema	KeySchema	The schema to register

Returns

void