A2UI Files

• BREAKING: Module paths and validation interfaces moved or changed in v0.2.0. Deprecation shims are provided for renamed public module paths; importing them emits a DeprecationWarning naming the new path. These shims will be removed in v0.3.0.

Shimmed Modules (Deprecated; removal in v0.3.0):

Unshimmed Internal Modules & Renames:

Internal modules were moved without shims; callers should import from the new paths directly:

• a2ui.core.rendering (and .component_context, .data_context, .generic_binder): moved to a2ui.core.resolution (and matching submodules).
• a2ui.core.validating (and .integrity_checker, .topology_analyzer): moved to a2ui.core.validation (and a2ui.core.state.validation_helpers).
• validate_component_integrity: moved to a2ui.core.validation as (components: dict[str, ComponentModel], root_id: str = ROOT_ID, config: ValidationConfig | None = None) -> None.
• analyze_topology: moved to a2ui.core.validation as (components: dict[str, ComponentModel], root_id: str = ROOT_ID, config: ValidationConfig | None = None) -> set[str].

Removed Modules and APIs:

• BREAKING: DataModel stores data values by reference instead of making deep copies. Callers that mutate nested objects after setting them in DataModel will update internal state directly.
• BREAKING: A2uiRpcError argument order is now (message, code, ...).
• BREAKING: DataModel.set now raises A2uiDataError instead of resetting the root when attempting to traverse or set a subpath under a primitive root value.
• BREAKING: SurfaceComponentsModel.add_component now raises A2uiStateError if a component with the same ID already exists in the model.
• BREAKING: pending RPC requests on RpcHandler.dispose() are now rejected with error code CANCELLED (previously DISPOSED).
• SurfaceModel now accepts a root_id parameter (defaulting to "root") and provides a deprecated catalog property aliasing default_catalog.
• SurfaceComponentsModel.detect_cycles now correctly ignores disconnected orphan components by passing allow_orphan_components=True to topology analysis, reporting cycle and depth limit violations exclusively.
• Bound function calls to MAX_FUNCTION_CALL_ARGS (1,000 arguments) across both PayloadValidator.validate_function and runtime DataContext._execute_function resolution.
• Bound expression template strings to MAX_EXPRESSION_TEMPLATE_LENGTH (10,000 characters) and parsed expression segments to MAX_EXPRESSION_PARTS (1,000 parts) in ExpressionParser.
• Add SemVer parsing and comparison utilities (SemVer, compare_semver, is_at_least_version, normalize_version_string, parse_semver, to_canonical_version, to_semver) in a2ui.core.common.semver.
• Add A2uiProtocolVersion and ProtocolVersion enum in a2ui.core.schema.
• Remove A2uiCompileError from a2ui_core exception hierarchy.
• BREAKING: locale formatting now comes from CLDR by way of babel, replacing the hand-rolled locale tables. Currency, number, date month and weekday names, and plural category selection now match what the TypeScript engine gets from Intl. That was the point: the two engines previously disagreed for every locale other than en-US, on the symbol chosen and on which Unicode space separates it from the amount.

a2ui.core.basic_catalog no longer exports LocaleFormattingRules, register_locale_rules, get_locale_rules or CURRENCY_SYMBOLS, and locale_config.py is deleted. register_locale_rules was the extension point for registering a custom locale; that capability goes away rather than moving, because babel resolves locales from CLDR only.

babel is added as a runtime dependency.

babel reads its patterns and symbols from CLDR but does not implement CLDR's currencySpacing, which ICU does apply. The package supplies that rule itself, so a currency whose symbol is alphabetic is separated from the amount by U+00A0 as Intl separates it: CHF 1,234.56, not CHF1,234.56. This affects the assigned codes CHF, SEK, DKK, CZK and PLN among others, in en-US as well as elsewhere.

One difference from Intl remains. For Arabic locales such as ar-EG, Intl shapes digits in Eastern Arabic numerals while babel emits Latin ones. babel offers no way to close this: requesting the locale's default numbering system converts the separators but not the digits, which agrees with neither engine.

A locale tag the catalog cannot use falls back to en_US rather than raising. babel raises for a malformed tag and for a well-formed tag CLDR does not carry, such as xx-YY, either of which would otherwise abort every format call made by a catalog built with it. The TypeScript engine falls back for the same tags.

• BREAKING: the Dynamic* schema aliases no longer coerce a value of the wrong primitive type. Each admits one primitive type, a data binding, or a function call, matching the TypeScript engine and the specification. What changes in practice:
• DynamicNumber rejects the string "1", which previously validated as 1.0, and rejects True, which previously validated as 1.
• DynamicBoolean rejects 1, 0 and "true", which previously validated as True, False and True.
• DynamicValue keeps an integer as an integer. It admitted float but not int, so a payload carrying 1 came back as 1.0.
• DynamicString and DynamicStringList are now declared strict for consistency. This is not a behaviour change: pydantic already refused to coerce other primitives into a string.

Data bindings and function calls are unaffected.

• The v0.9 and v1.0 basic catalogs no longer register add, subtract, multiply, divide, equals, not_equals, greater_than, less_than, contains, starts_with or ends_with. The published catalogs declare exactly 14 functions, and none of these operators is among them, so an agent had no way to know they were callable. a2ui.core.basic_catalog no longer exports their API classes or implementations, aligning Python engine behavior with the reference typescript implementation.

• The v1.0 formatDate ISO pattern now returns the UTC instant with exactly three fractional digits, as web_core does. It previously echoed back whichever offset the input carried, so 2025-01-01T12:00:00+02:00 formatted as itself instead of 2025-01-01T10:00:00.000Z. A timestamp without an offset is read as UTC, so the result no longer depends on the host time zone.

• The v1.0 pluralize function now falls back to the other form only when the selected category is absent, not when its value is empty. A caller that supplies zero: "" gets an empty string, matching web_core; previously the empty form was discarded and the other form rendered in its place.

• ExpressionParser.MAX_DEPTH is 100, up from 10, matching web_core and the Swift engine. An expression nested between 11 and 100 levels deep was rejected here and accepted there.

• A function-call argument now counts toward the expression parser's recursion depth, as it does in web_core. Only nested interpolations were counted before, so ${f(a: ${f(a: ...)})} written as ${f(a: f(a: ...))} recursed unchecked and raised RecursionError from the interpreter rather than a parse error.

• Catalog.from_json accepts a common_types_schema argument and rewrites cross-document references such as common_types.json#/$defs/ChildList into local #/$defs/... pointers, satisfying them from the supplied document or from the built-in definitions. Catalogs that reference the published shared types now load without the specification/ tree on disk, and the validator no longer reads schema files at runtime.

• Deleting a list index past the end of the list is now a no-op. It previously padded the list with None up to that index, so deleting /items/10 from a three-element list produced an eleven-element list.
• The shared type definitions used to satisfy common_types.json references are now checked against the published document by a test, with an explicit list of the definitions that intentionally differ. Descriptions on AccessibilityAttributes, DynamicString, DynamicNumber and DynamicBoolean were brought back into line with the specification.
• The conformance harness now fails, rather than silently skipping, when a suite cannot be parsed, when a case has no name or action, or when an action has no handler. Suites the core library cannot run are named in UNRUNNABLE_SUITES with a reason.

Published to PyPI: a2ui-core 0.2.0

:::sh
pip install a2ui-core==0.2.0