Dual-emit tracking

Package markdown: docs/TRACKING.md. Composition method → Composition.

Three error layers

1. fx — parse / typecheck / borrows → fx check
2. C / link — after emit → fx cc remaps via .fxmap
3. Runtime — ASan / asserts / gdb (use #line + -g)

Always prefer layer 1 first.

Emit modes

• Annotate (default) — /* fx: … */ comments
• Debug source — --debug-source → .fxmap + #line
• Minimal — --minimal (smallest C)

fx emit-c main.fx -o out_c --debug-source
fx locate --c-file out_c/main.c --line 42

Related

• CLI — emit-c, cc, locate, mcp
• Composition — how to build under regions