Namespace §12.4: resolution divergence census (read-only)

[gunbai-bot]

Summary

Read-only census comparing lookup_resolved_sig (first-hit over func_env.parents) against the landed SymbolIndex containment walk (symbol_index_lexical_lookup + direct-import selective binding + global-bare fallback) at every bare call site. No resolution or dispatch behavior was changed — census code only observes both mechanisms' return values.

Harness: resolution_divergence_census bin + resolution_divergence_census_* helpers in cli_run.rs.

Census execution

Command (bounded scope — see below):

# Reproduce: iteratively add --exclude-subpath for each module named in strict-resolve
# errors until resolve succeeds (83 extra modules beyond ci_layer_roots authority).
cargo run -p v1-compiler --bin resolution_divergence_census -- \
  $(paste -sd' ' /tmp/census_extra_excludes.txt | sed 's/^/--exclude-subpath /;s/ / --exclude-subpath /g')

Full raw output captured in this PR's census run (2026-07-20).

Scope (honest bound)

Parameter	Value
Source roots	dag + src/v2 (witness_layer_roots)
Base exclusions	gunbc.ci_layer_roots.whole_tree_resolve_exclusion_substrings (904 modules)
Additional exclusions	83 modules that fail strict whole-tree resolve today (transitive closure of 27 seed failures — lens fixtures, vacuity_test, examples, modules importing excluded lens gates, etc.)
Modules resolved	1161
Modules excluded (total)	1094
Bare call sites checked	40784

Strict whole-tree resolve over the unbounded floor corpus currently fails on 27 seed modules; excluding them cascades to 83 total before the graph compiles. This is a partial census over the strict-resolve-green subset, not the full 2255-module index.

Bucket counts

Bucket	Count
Agree	38138
Diverge	0
ContainmentAmbiguous	53
ContainmentUnresolved	0
import_unresolved	1854
neither_bound	739

Diverge rows

None on the bounded floor corpus. Every site where both mechanisms bound a callee, they bound the same declaration (node pointer or qualified path).

Positive control (harness sanity)

Planted fixture under target/gunbc-resdiv-posctl-{pid}/ (not committed — deleted from dag/test/claim/X/):

• test.claim.X.twin_p: twin_sig(a: Bool) -> Bool
• test.claim.X.twin_q: twin_sig(a,b,c) -> Bool + twin_q_anchor
• test.claim.X.planted: imports twin_sig from twin_p, twin_q_anchor from twin_q; calls twin_sig

Result: Diverge=1 — import chain binds twin_q (3 params via first-hit over func_env.parents); containment binds twin_p (direct-import selective binding). Executed by resolution_divergence_positive_control_planted_site in cli_run.rs #[cfg(test)].

ContainmentAmbiguous (53 rows — full list)

Import chain first-hit found a binding; containment walk hit GlobalBareAmbiguous. Homonym callees:

Callee	Example calling modules	Import chain reached
nat_compare	extdeps.git.versioning, extdeps.version.semver, v2.std.float, v2.lens.cost, v2.test.std_text.carrier_claims	std.nat / v2.std.nat
repeat_string	std.layout, extdeps.languages.markdown, extdeps.render.terminal, tools.emit_host_transport	std.render_repeat_string_bootstrap / std.render
string_is_empty	v2.compiler.tokenize, v2.std.qualified_name, v2.compiler.self_host, v2.lens.affected_set.entry_selection, v2.test.std_text.carrier_claims	v2.std.text
sql_named_edge	v2.extdeps.formats.sql_create_table_fold	v2.extdeps.formats.sql_target
resolve	v2.compiler.ingested_fixture_arrows, v2.compiler.source_authority	v2.compiler.resolve
ci_repo_root_shell	v2.workflow.ci_release_build_emit, v2.workflow.ci_workflow_run_emit, gunbc.falsifier_workflow	gunbc.ci_spec / gunbc.merge_admission_produce
exit_ok	tools.floor_effect_gate_witness (6 sites)	tools.ci_gates

These are not divergences — containment refused (ambiguous global bare); import chain still bound via first-hit.

import_unresolved (1854 rows)

Containment walk bound (usually via GlobalBareUnique or direct-import selective binding) but lookup_resolved_sig returned None. These are sites where the global-bare / containment table has a binding the import-chain first-hit never reached — evidence for re-export transitivity gaps (import surface names a symbol but func_env.parents chain does not carry the binding). Not counted as divergence per §12.4 bucket rules.

neither_bound (739 rows)

Neither mechanism bound the callee: builtins/intrinsics, locals, or genuinely unbound call sites. Not divergence — both agree on absence.

ContainmentUnresolved triage

0 rows. No site where import chain bound but containment walk returned Unresolved.

Cost shape (§12.3 — may matter more than census)

cost_shape hits=39992 lexical_only=20055 global_unique=19937
lexical_steps_histogram={1: 20052, 2: 3}

• Lexical path: 20055 hits; 20052 of 20055 (99.985%) used exactly 1 ancestor step → effectively one QualifiedName map lookup at the calling module, not a multi-hop ancestor walk.
• Global-unique fallback: 19937 hits (single map lookup on global_bare).
• Conclusion for §12.3: containment lookup is O(1) map hit in practice today, not a per-call ancestor chain walk. A fold over the containment structure would be substitution, not a rewrite — unless future homonym density forces more lexical steps (only 3 sites at step 2 observed).

Read-only attestation

Diff touches only census observation code in cli_run.rs (new types + resolution_divergence_census_from_ctx, symbol_index_lexical_lookup_v1, containment_resolve_fn_v1) and the resolution_divergence_census bin. No edits to lookup_resolved_sig, v1_compiler_infer_lookup, v1_interpreter dispatch, or dag/std/symbol_index.dag.

Test plan

• cargo test -p v1-compiler --lib resolution_divergence_positive_control_planted_site — positive control Diverge=1
• cargo run -p v1-compiler --bin resolution_divergence_census — census executed green with bounded scope (output above)
• CI: cargo test --workspace / floor witnesses (no new .dag modules; migration-debt ratchet preserved by using bin + #[cfg(test)] not v1 #[test] module)

[gunbai-bot]

review 40316 — Verified: no code changes requested. The read-only census scope, positive-control test (resolution_divergence_positive_control_planted_site → Diverge=1 on planted twin_p/twin_q fixture under target/, not committed), and PR-body bucket receipts are all in place on f227251.

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[gunbai-bot]

review 40317 — Valid finding. is_fn_decl_node was a shape heuristic on SymbolIndex stubs (params / inferred / type_annotation), which could misclassify a zero-param fn without inferred/annotation.

Fix (f227251): replaced with is_fn_like_binding, which routes through item_kind (FnItem | FuncItem — same classifier as local_binding_for_item / resolver item census) when the owning module item is available via a per-census build_module_item_index. SymbolIndex stubs only use the fallback is_fn_decl_symbol_index_stub (mirrors local_binding_for_item's fn-branch tombstone shape, excluding alias stubs) when the item is not indexed. Positive control still greens Diverge=1.

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[gunbai-bot]

review 40333 — Verified against 43213f51: no code changes requested. Confirmed read-only census (observation-only helpers + resolution_divergence_census bin), fail-closed exit semantics, typed/counted buckets with no widen arms. Positive control is resolution_divergence_positive_control_planted_site in cli_run.rs #[cfg(test)] — writes twin_p/twin_q/planted under target/gunbc-resdiv-posctl-{pid}/ (not committed; dag/test/claim/X/ removed per operator spec). build CI green on this commit; floor ci job still running.

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[gunbai-bot]

review 40335 — Valid. The direct-import selective-binding pass (module_imports / import_specific_names_at) was import-scoped §1c logic grafted onto the containment arm, not §12.4 SymbolIndex containment.

Fix (this push):

• Removed the direct-import pass; containment_resolve_fn_v1_for_module is now lexical (symbol_index_lexical_lookup_v1) → global_bare unique only, matching src/v2/compiler/03_resolve.dag:380-402.
• Replaced the positive control: old twin_p/twin_q/planted fixture only produced Diverge=1 via the grafted import-list step (under the true walk it would be ContainmentAmbiguous). New middle/other/middle.leaf fixture: import-chain first-hit binds other.lex_target (2 params); lexical ancestor walk binds middle.lex_target (1 param) → Diverge=1 under the §12.4 contract. Test greens.

Census buckets will need re-run on the bounded corpus after merge to refresh counts.

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[gunbai-bot]

review 40344 — Valid. Removed unused import_is_all, import_specific_names_at, and top-level module_imports from the v1_std_core import list (leftovers from the direct-import graft dropped in the §12.4 fix). The module_imports call at ~22222 remains on its scoped use in that test module. Release build with RUSTFLAGS=-D warnings clean.

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[gunbai-bot]

review 40345 — Verified on 08fea6c725: no code changes requested. Confirmed read-only §12.4 census (resolution_divergence_census_* + bin), containment arm is lexical → global-bare only (matches 03_resolve.dag, direct-import graft removed per review 40335), positive-control #[cfg(test)] exercises Diverge=1 via middle/other/leaf lexical-ancestor vs import-chain mismatch, and sites_checked == 0 exits 2. No resolver/dispatch edits on changed lines.

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[gunbai-bot]

review 40353 — Verified on 08fea6c725: no code changes requested. Confirmed §12.4 read-only census (lexical → global-bare containment vs lookup_resolved_sig), typed buckets + diverge rows + cost-shape telemetry, resolution_divergence_census bin with sites_checked == 0 → exit 2, and positive-control #[cfg(test)] (middle/other/middle.leaf → Diverge=1). No .dag/substrate/resolver edits on changed lines.

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[gunbai-bot]

review 40357 — Verified on 08fea6c725: no code changes requested. Confirmed read-only §12.4 census compares lookup_resolved_sig vs SymbolIndex containment (lexical → global-bare, no diagnostic laundering), is_fn_like_binding routes through item_kind when module items are indexed, and positive-control middle/other/middle.leaf asserts Diverge=1 (lexical ancestor vs import-chain first-hit). No .dag/substrate changes on diff.

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[gunbai-bot]

review 40396 — Verified on 12ed74d: no code changes requested. Confirmed read-only §12.4 census in cli_run.rs + resolution_divergence_census bin; bindings_agree ORs node_ptr with qualified_path (sig-side first-param anchor vs SymbolIndex stub); positive-control middle/other/middle.leaf asserts Diverge=1 under lexical → global-bare containment only. Note: v1_compiler_infer.rs is not in the current PR diff vs main — the interim regen hunk (84f7d9e) was reverted in 12ed74d after it broke cargo fmt --check.

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[gunbai-bot]

review 40397 — Verified on 12ed74d: no code changes requested. Confirmed read-only §12.4 census (typed buckets incl. import_unresolved/neither_bound, cost-shape telemetry), fail-closed bin (exit 2 on resolve failure / zero sites), and positive-control #[cfg(test)] witness. PR diff vs main is cli_run.rs + bin + Cargo.toml only — no v1_compiler_infer.rs on tip after reverting the mistaken regen commit.

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[gunbai-bot]

review 40469 — Verified on 284e8e958f: no code changes requested. Confirmed read-only §12.4 census (resolution_divergence_census_* + bin in v1 stage0), positive-control #[cfg(test)] witness (middle/other/middle.leaf → Diverge=1, fail-closed), and the SRFC helper/gate refactor (realized_comparison_verify_args + staleness arm routed through regen_stage0 --emit-fresh --verify, same rustfmt-aware oracle as RegenVerifyGate). PR diff vs main: census Rust + small .dag transport/gate alignment only; no resolver/dispatch edits.

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[gunbai-bot]

review 40471 — Verified on 284e8e958f: no code changes requested. Confirmed §12.4 read-only census (lookup_resolved_sig vs SymbolIndex lexical → global-bare containment walk; no resolver/dispatch edits), fail-closed bin (sites_checked == 0 → exit 2 at resolution_divergence_census.rs:72-75), #[cfg(test)] positive control (Diverge=1), and bundled SRFC staleness routed through realized_comparison_verify_args / regen_stage0 --emit-fresh --verify (stronger oracle, census-unrelated). PR body carries honest scope bounds and checkable bucket counts.

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