Macro Expansion Tracing

[aalpar]

Summary

Enable tracing of macro-generated code back to source: which macro, which invocation, definition-site location.

Design

See plans/MACRO_EXPANSION_TRACING.md for full design.

Key Addition

syntax-origin primitive for Scheme-level inspection.

Tasks

• Extend OriginInfo with new fields (IntroScope, UseSite, Template)
• Add Scope.ID() method
• Populate fields during expansion
• Add syntax-origin primitive
• Verify unique scope IDs per invocation

Use Cases

• Error messages pointing to template source
• Macro debugging
• Understanding expansion process