frontend/gda_expr Design

Pipeline And Selection

The package parses GDA .decTest text into immutable contexts, cases, source spans, and numeric_expr trees. Directive state is snapshotted into each case. Execution normalizes operation names, classifies the case before evaluation, maps supported operations to Decimal context APIs, and compares both result cohort and flags. Deterministic sharding selects by stable case position.

Capability Boundary

Cases are explicitly Executable, Diagnostic, Legacy, or Unsupported. For the pinned official corpora, diagnostics are only # placeholder/non-scalar invalid inputs; legal rows have zero legacy and unsupported classifications and all pass. The package does not download corpora, read files, spawn processes, or implement decimal arithmetic. Python tooling owns corpus staging; cli/gda_expr_cli owns filesystem and process exit behavior.