v2 bootstrap: generic lambda-param instantiation from call-site type — dissolves the 3-instance fold-consumer gap class (design ruling tidy-stag-172, dep-graph-2026-06-12 §4a). Extend v2 R2 minimal generic instantiation so: (a) fold_list/fold_list_right cons|snoc callbacks bind T from xs: FreeMonoid

[briansrls]

Auto-opened by session-dashboard for session swift-deer-774.
Pushing to session/swift-deer-774-nodefold advances this PR.

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Summary

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Test plan

• TODO: list the commands that ran (or "no tests changed; relied on CI") and the outcome.

[briansrls]

Verified composer-2.5 APPROVE artifact against current HEAD (ecff06e22c) — no code changes needed.

Finding triage: Review reports no findings; spot-check confirms:

• Scope is v2 inference only (04_infer.dag + mirrored v2_compiler_infer.rs); no src/v3/ hand-Rust or std/ substrate edits.
• is_record_lit_expr follows the existing is_lambda_expr pattern in the same file.
• Tests align with TESTING.md: hermetic inline sources, fail-closed red test (generic_instantiation_field_checks_concrete_type_red), running NodeFold consumer (v4_nodefold_topdown_inline_algebra_compiles_and_runs), chained field access compile-gated with explicit #[ignore] runtime follow-up.
• unify_generics fail-closed conflict handling preserved.

Post-review delta (does not invalidate approval): lookup_applied_field_type_node was removed and stage0 regen'd in ecff06e22c after it broke Validation<B>.admits in lens/emit gates. Field access now uses lookup_field_type_node on resolve_scrutinee only. ci_floor_emit and full CI are green on HEAD.

Merge readiness (2026-06-12):

Gate	Status
CI (12 checks on ecff06e22c)	✅ green
mergeStateStatus	✅ CLEAN
REQUEST_CHANGES	✅ none
api-review approvals	⚠️ 1 (composer-2.5) — needs ≥2 distinct before operator merge

Standing by for second api-review approval.

— sent from swift-deer-774

[briansrls]

Finding triage: lookup_applied_field_type_node orphan in stage0 — already addressed on HEAD.

The REQUEST_CHANGES finding was valid at review time (12:49Z): stage0 had ~95 lines of lookup_applied_field_type_node with no .dag definition, violating INVARIANTS P2.

Fix already landed (no further commit needed):

Commit	Change
656c6cec9c	Removed dead helper from 04_infer.dag; field access uses lookup_field_type_node on resolve_scrutinee only
ecff06e22c	Regen stage0 — deleted orphan from v2_compiler_infer.rs (96 lines removed)

Verification on HEAD (ecff06e22c):

• git grep lookup_applied → empty (no matches in repo)
• v2_compiler_infer.rs:1100 is now KernelListTyDiag struct, not the orphan fn
• cargo run -p v2-compiler --bin regen_stage0 -- --verify → pass (committed stage0 matches fresh self-compile)
• CI green including ci_floor (stage0 freshness gate)

The generic-instantiation work in 04_infer.dag (record-lit expected-type substitution, type_node_label/TypeVariable binding, unify_record_lit_generics) is unchanged and still covered by tests.

Merge readiness: CI ✅ CLEAN ✅ · REQUEST_CHANGES finding resolved · still need ≥2 distinct api-review APPROVEs (currently 1 APPROVE + 1 REQUEST_CHANGES on superseded SHA).

— sent from swift-deer-774

[briansrls]

Finding triage: claude-opus-4-7 APPROVE — verified on HEAD, no code changes needed.

Spot-checked the approval claims against ecff06e22c:

• Scope: v2 .dag generic instantiation + regen stage0 mirror only; no hand-Rust in src/v3/. P5 N/A.
• Helpers present as described: record_lit_expanded_from_expected, record_lit_fields_from_expected, record_lit_instantiated_fields, should_unify_record_lit_generics, unify_record_lit_generics, unify_record_lit_field_walk, type_node_label.
• is_record_lit_expr mirrors is_lambda_expr at 04_infer.dag:1348–1360 (single-variant ExprData test).
• param_is_generic_decl fallback requires is_type_variable(inferred) before pname == pt.name — user type T misclassification guard preserved.
• substitute_generics short-circuits on TypeVariable { id } before bare-name lookup; empty-subst identity no-op preserved.
• P2 sync: git grep lookup_applied empty; regen_stage0 --verify passes (orphan stage0 fn removed in ecff06e22c, addressing prior REQUEST_CHANGES).
• Tests: NodeFold running witness green; chained field access compile-gated with explicit #[ignore] runtime follow-up.

Merge readiness (2026-06-12):

Gate	Status
CI (12/12 on ecff06e22c)	✅
mergeStateStatus	✅ CLEAN
api-review APPROVEs	✅ 2 distinct (composer-2.5 + claude-opus-4-7)
Prior REQUEST_CHANGES (orphan stage0)	✅ resolved on HEAD
Operator merge	⏸ awaiting manual merge per policy

No further code work from this session.

— sent from swift-deer-774

[briansrls]

Finding triage: composer-2.5 APPROVE (28661) — verified on HEAD, no code changes needed.

Spot-checked against ecff06e22c:

• Item (b): v4_nodefold_topdown_inline_algebra_compiles_and_runs at nodefold_generic_instantiation_test.rs:62-74 — compile + interpreter run to Int(8).
• Item (c): compile gated at :78-80; runtime explicitly deferred with #[ignore] at :84 — bounded deferral, not an unmarked gap.
• Scope: v2 generic instantiation in 04_infer.dag + stage0 regen only; no v3 hand-Rust; item (a) fold_list/FreeMonoid not touched in this diff.
• Inference: record-lit generic binding, type_node_label/substitute_generics, fail-closed unify_generics conflict handling coherent.
• P2: regen_stage0 --verify passes; no orphan stage0 symbols.

Merge readiness: CI ✅ (12/12) · CLEAN ✅ · ≥2 APPROVEs (composer-2.5 ×2 artifacts + claude-opus-4-7) · prior REQUEST_CHANGES resolved on HEAD · awaiting operator manual merge.

— sent from swift-deer-774