Resolution

This section is the Architecture Spec's versioned description of how the frontend resolves source spellings to stable identities, and the boundary that binds typechecking, elaboration, and evaluation to those identities instead of re-deriving meaning from names. It documents the implemented resolved-identity model described by ADR-0054; the arch-* requirements below are its checkable claims.

Owning crate: metel-frontend. The model is defined in identity/ (mod.rs, allocate.rs, lexical_path.rs, member.rs, position.rs), and consumed by name_resolver.rs, reference_resolver.rs, typed_ast/, and every later pipeline stage.

Model

The resolution freeze separates source spelling from durable semantic identity. Every reference is total—local or global—and later stages consume that result rather than looking the spelling up again (frozen references). Lexical bindings and uses receive structural identities that survive unrelated edits (lexical identity); fields and variants receive the same treatment at the declaration level (member identity). The walk leaves no code uncovered: a module's bare top-level statements get identities too, and a top-level declaration's span maps to its symbol (coverage).

Editor lookup is intentionally different. A position index maps an ephemeral parsed snapshot back to these identities, but position never becomes a semantic key (position isolation). This distinction lets tools be responsive without making formatting alter program meaning.

Verifiable architecture claims

Owner metel-frontend unless a requirement names another.

Requirement №1

Once inference has solved a body and the frontend has frozen its resolution, no later phase looks anything up by source spelling: every meaning is found by a stable identity, and every value reference has a total Resolution (Global(SymbolId) or Local(LocalId)), with no silent unresolved case.

Related: ADR-0054, ADR-0041, ADR-0042

Implemented by (1)

• allocate_module metel-frontend/src/identity/allocate.rs

Tested by (3)

• a_body_with_only_bound_names_has_no_unresolved_references metel-frontend/src/identity/tests.rs
• a_use_of_a_global_declaration_is_classified_as_global metel-frontend/src/identity/tests.rs
• reference_table_is_total_and_unknown_names_are_explicit metel-frontend/src/identity/tests.rs

Requirement №2

Bindings and value references get structural identities (LocalId, RefId) from a parse-driven walk keyed on LexicalPath, not on byte offsets or traversal counters, so reformatting, an earlier sibling binding, or an edit to another body does not change an existing identity.

Related: ADR-0054 (2026-09-10 amendment)

Implemented by (1)

• allocate_module metel-frontend/src/identity/allocate.rs

Tested by (3)

• blank_lines_and_reformatting_change_no_identity metel-frontend/src/identity/tests.rs
• editing_one_body_leaves_another_bodys_identities_untouched metel-frontend/src/identity/tests.rs
• inserting_an_earlier_binding_does_not_renumber_a_later_one metel-frontend/src/identity/tests.rs

Requirement №3

Struct fields and enum variants are interned to stable FieldId / VariantId, keyed by (owning type SymbolId, member name) before inference, and threaded onto the typed IR as Option<FieldId> / Option<VariantId> rather than re-derived from a string.

Related: ADR-0054 step 3, #1051

Implemented by (1)

• collect_members metel-frontend/src/identity/member/mod.rs

Tested by (6)

• absent_members_report_none_not_a_fabricated_id metel-frontend/src/identity/member/tests.rs
• enum_variants_and_their_fields_are_interned metel-frontend/src/identity/member/tests.rs
• interning_is_reformat_stable_and_order_independent metel-frontend/src/identity/member/tests.rs
• same_field_name_on_different_types_is_a_different_id metel-frontend/src/identity/member/tests.rs
• struct_fields_get_distinct_ids_owned_by_the_struct metel-frontend/src/identity/member/tests.rs
• typed_ir_threads_member_ids_rather_than_rederiving_them metel-frontend/src/pipeline/type_checking/tests.rs

Requirement №4

PositionIndex is the one byte-position-keyed lookup: rebuilt from a parsed snapshot, never persisted, never a semantic input. BindingSpans is a transient construction-time bridge; every durable resolved artifact (ResolutionMap, the frozen IR) is keyed by identity, not position.

Related: ADR-0054 (2026-09-10 amendment)

Implemented by (1)

• from_entries metel-frontend/src/identity/position.rs

Tested by (3)

• module_segment_hit_is_position_stable_under_reformatting metel-frontend/src/identity/tests.rs
• position_index_finds_a_use_and_misses_whitespace metel-frontend/src/identity/tests.rs
• the_durable_resolution_map_is_keyed_by_identity_not_position metel-frontend/src/identity/tests.rs

Requirement №5

The identity walk covers every body of code, including a module's bare top-level statements (walked as one block under a per-module owner), and maps a top-level declaration's own span to its SymbolId.

Related: ADR-0054, #1570

Implemented by (1)

• allocate_module metel-frontend/src/identity/allocate.rs

Tested by (1)

• bindings_in_top_level_statements_have_distinct_identities metel-frontend/src/identity/tests.rs

Known limitations

acceptedLIMIT-RESOLUTION-001 — Resolved-identity model is in-memory only. Resolved identities exist only in memory; nothing persists them across processes. Open record ↗knownLIMIT-RESOLUTION-002 — Inference-time type lookup falls back to a name-approximate, cross-module search. Inference falls back to a name-based, cross-module type lookup where the declaration id is missing, which can confuse same-named types. Open record ↗