Replaces the old remove_definitions_for_document + invalidate_ancestor_chains approach with a targeted invalidation engine. When a file is updated or deleted, the engine traces through the name_dependents reverse index to invalidate only the affected declarations, names, and references — instead of requiring a full graph rebuild.

How it works

consume_document_changes() (renamed from update()) and delete_document() run a three-step pipeline:

1. invalidate — read-only scan that seeds a worklist from old/new definitions and references, building a pending_detachments side table for definitions that need to be detached from their declarations
2. remove_document_data — cleans up phase 1 data (definitions, references, names, strings) from maps
3. extend — merges new content and queues work items for the resolver

The resolver still does clear_declarations + full rebuild. Wiring it to drain pending_work incrementally is a follow-up.

Invalidation worklist

The worklist processes three item types:

• Declaration — two modes:
  • Remove: no definitions remain or owner was already removed (orphaned). Cascades to members, singleton class, and descendants. Orphaned definitions are re-queued for re-resolution (e.g. class Foo::Bar survives even if Foo changes from a module to an alias).
  • Update: declaration survives but its ancestor chain may have changed (mixin added/removed, superclass changed). Clears ancestors/descendants and re-queues ancestor resolution.
• Name — structural dependency broken (name's nesting or parent scope removed). Unresolves the name and cascades to all dependents.
• References — ancestor context changed, but the name itself is still valid. Needed for mixin-related invalidation:

class Foo < Bar
  CONST
end

# Another file adds:
class Foo
  include Baz # Foo's ancestors changed, so references like CONST need re-evaluation
end

Cascade differentiation

The name_dependents reverse index distinguishes ChildName (compact syntax Foo::Bar) from NestedName (nested syntax module Foo; class Bar; end; end):

• Structural cascade (name removed): both ChildName and NestedName → Name
• Ancestor-triggered cascade (mixin changed): ChildName → Name (resolves through parent), NestedName → References (only references need rechecking)