Module relation 

The structural edge-relation vocabulary, defined ONCE so the producer (compile) and the consumers (retrieval) can’t drift on a typo’d string literal. (Typed frontmatter relations — depends_on, produces, … — live in compile::REL_FIELDS.)

Constants

CONTAINS

A container holds a declared item: module→item, type→method (from syntax).

HAS_KNOWLEDGE

A SKILL.md owns the docs under its directory (structural ownership).

IMPLEMENTS

A type implements a trait (impl Trait for Type) — from syntax.

LINKS_TO

An explicit [[wikilink]] the author wrote.

MENTIONS

An unlinked lexical mention — the candidate/noisy class (not traversed in expansion).

REFERENCES

A symbol’s body lexically names another known symbol — the candidate/noisy class.