feat(v3): E6-G0b X1.a static call-on-field-access (parse + lower)

[briansrls]

Summary

Implements E6-G0b / Prereq-X1.a: static call-on-field-access dispatch where the callee path resolves through a data binding's structural value body to a top-level function reference. Per the merged worker brief r3-pr-e6-g0b-x1a-static-field-call-worker.md (#1657).

Implemented

• Parse-surface schema: SurfaceExpr::PathCall { segments, segment_spans, args, span } added to src/v3/std/parse_surface.dag (sibling of Path and Call). parse_surface_generated.rs mirrored.
• Parser: parse_ident_expr peeks for LParen after the dotted-segment loop and emits PathCall. parse_pipe_call::target_expr rejects PathCall with a typed parse-error mirroring the existing Path arm. expr_span updated for the new variant. regen_parse re-emitted parse_generated.rs.
• Lowerer: new SurfaceExpr::PathCall arm in lower_expr that:
  • empty path → typed ResolveError;
  • parameter-callee head (X1.b) → typed ResolveError naming the Prereq-X1.b substrate prerequisite;
  • non-data head → typed ResolveError;
  • missing/non-Reference leaf → typed ResolveError ("non-Arrow / non-callable / missing");
  • non-callable leaf decl (Arrow check via declaration_is_callable) → typed ResolveError;
  • anonymous resolved decl → typed ResolveError;
  • else: synthesizes SurfaceExpr::Call { target: <resolved_name>, args, span } and recurses into lower_expr so the existing static-callable lowerer performs arity + per-position type validation. No new TransformTarget variant; no TransformDispatch collapse.
• Termination analysis (P4 Decidability): is_recursive, descent_provable, and collect_recursive_callees now thread dag and symbols so a PathCall whose resolved leaf decl name equals self_name (or whose leaf decl is in the recursive-callee set) participates in mutual-recursion / descent analysis. resolve_field_value_reference is the shared resolver.
• Helpers: resolve_field_value_reference walks structural ValueBody segments to a leaf FieldValue::Reference(decl_id). Used by the lowerer arm and all three termination-analysis functions — single resolution authority.
• Exhaustive-match arms: added PathCall arms in lower_helpers_generated.rs (regen target — paired lenses/lower_helpers.dag updated), refinement_predicate_out_of_fragment, collect_scope_bound_free_vars, collect_lambda_free_names, is_recursive, descent_provable, is_structurally_smaller is wildcard (no arm needed), ClusterDescentChecker::expr, and collect_recursive_callees.
• Ratchet test split: src/v3/compiler/tests/integration/prereq_x_call_on_field_access_ratchet_test.rs split into 5 tests:
  • control_arrow_typed_field_decl_parses (unchanged)
  • x1a_static_data_field_call_lowers_to_callable — positive Dag-shape assertion (TransformTarget::Callable(decl_id_of_double))
  • x1a_non_arrow_field_call_diagnostic — typed lowering ResolveError on non-Arrow leaf
  • x1b_parameter_field_call_blocked_at_lowering — parses cleanly, lowering returns typed ResolveError naming the X1.b prerequisite (replaces prior parse-error LParen ratchet)
  • x3_brace_block_with_let_head_blocked (unchanged)

All 5 ratchet tests pass.

Parse-surface carrier-addition discipline (per #1657)

1. Why a sibling variant is the smallest honest carrier. Call.target: String collapse would smuggle a dotted path into a single String (opaque-string anti-pattern, feedback_opaque_strings_attract_heuristics). Widening Call.target to a path-shape would touch every existing Call-consumer site — wider blast radius than this slice warrants. A sibling variant keeps the existing Call shape unchanged.
2. Why this is not an opaque-string target. segments: List<String> is structured, with per-segment SourceSpan carried by segment_spans. No .-separated string parsing anywhere downstream.
3. Generated files changed by this slice.
   • src/v3/compiler/src/parse_surface_generated.rs — SurfaceExpr variant emission (paired with src/v3/std/parse_surface.dag).
   • src/v3/compiler/src/parse_generated.rs — parse_ident_expr body splice + expr_span arm (regenerated via cargo run --bin regen_parse).
   • src/v3/compiler/src/lower_helpers_generated.rs — expr_span arm (paired with src/v3/lenses/lower_helpers.dag).
4. Dissolution / scaffold status: 🟡 future-dissolve. Tracking gate identical to the existing docs/design-prereq-x-ho-field-call.md §X1.b dissolution ledger entry: when CalleeRef = Decl(...) | Field { … } | Port(ArrowPortRef) lands as a substrate carrier, X1.a-shaped programs lower as Call { callee: CalleeRef::Field { … }, args } and PathCall retires. Single classification surface — no parallel ROADMAP row.
5. Capability-vs-spelling. "Static call-on-field-access dispatch" is a permanent language surface; only the PathCall variant spelling is transitional. Mirrors the §X1.b "HO dispatch capability is permanent / variant spelling is transitional" split.

Validation

• cargo build -p v3-compiler ✅
• cargo build (workspace) ✅
• cargo fmt --all --check ✅ (pre-push hook)
• cargo clippy -p v3-compiler --all-targets -- -D warnings ✅
• cargo test --workspace prereq_x → 5/5 ratchet tests pass
• (workspace clippy fails on pre-existing v2-compiler-tests violations unrelated to this slice)

Fences honored

• ❌ No TransformDispatch / Indirect / ArrowPortRef substrate-shape changes
• ❌ No evaluator E6-G0c work (src/v3/compiler/src/lib.rs::evaluator::eval_transform_node unchanged)
• ❌ No test_runner.rs / TestPredicate work
• ❌ No fold_lens<C> authoring; fold_lens_over_reflected_program seam preserved
• ❌ No block-expression / X3 work (X3 ratchet remains red)
• ❌ X1.b parameter-callee remains red (lowering diagnostic, replaces prior parse-error)

#1532 debt receipt

Per-PR dissolution gate: no census shift; existing parse-surface authority remains the carrier for all surface expressions. New SurfaceExpr::PathCall variant carries 🟡 future-dissolve per §X1.b ledger; no new ROADMAP debt row opened. Lowerer reuses existing lower_expr Call dispatch via synthetic-Call; no new TransformTarget variant; no new Diagnostic shape (uses existing ResolveError).

Test plan

• cargo build workspace
• cargo fmt --all --check
• cargo clippy -p v3-compiler --all-targets -- -D warnings
• cargo test --workspace prereq_x (5/5 pass)

🤖 Generated with Claude Code

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: e3285cc9 · Trigger: schedule
• Thinking: 187s wall

---

BLOCKING (1)

Root Cause

• src/v3/std/parse_surface.dag SurfaceExpr schema changed without same-PR generated/parser/lowerer consumer cutover → regenerate parse_generated/lower_helpers and add a fail-closed lowering path for PathCall.

⚠️ The new surface variant needs to be carried through the compiled parser and lowerer before this can land.

[briansrls]

Finding is correct on the state — the PR is intentionally incomplete and explicitly STOP+PING, not 'ready to land.' See the PR body: schema variant landed, regen + ~25 exhaustive-match arms + lowerer + ratchet split are listed as remaining work, and three disposition options (A/B/C) are surfaced for parent. PR is in draft; no merge attempt is being made.

Awaiting parent disposition on whether to (A) extend ETA in place, (B) hand off, or (C) decompose into G0b.0 + G0b.1 PRs.

— sent from fierce-bear-784

[briansrls]

Same condition as the prior BLOCKING finding (already addressed). PR is intentionally draft + STOP+PING; PR body explicitly lists "Exhaustive-match arms across lower.rs and lib.rs for the new variant ... ~25 distinct match expressions ... parse_generated regen pending" as remaining work. No merge will be attempted until parent disposition selects (A) extend ETA, (B) hand off, or (C) decompose into G0b.0 + G0b.1. Both reviewer findings collapse to 'this PR is not yet complete' — agreed, and that is exactly what the STOP+PING PR body says.

— sent from fierce-bear-784

[briansrls]

Disposition on STOP+PING: choose A — extend ETA in place.

Keep this as one E6-G0b implementation PR and continue on the same draft branch. The expanded 4–6h scope is acceptable for this gate; splitting into a schema/parser-only PR would leave a new surface carrier merged before the positive X1.a lowering behavior exists, which is not worth the coordination churn unless you hit a hard blocker.

Implementation priority:

1. Finish regen so parse_generated.rs is updated from parse_parser_body.txt + parse_surface.dag.
2. Add the required exhaustive PathCall match arms. Mechanical sites should fail closed or recurse like Call/Path as appropriate; do not add semantic behavior outside X1.a.
3. Implement the lowerer arm for static data binding structural field references only.
4. Split the ratchets exactly as docs(r3): worker brief for E6-G0b Prereq-X1.a static field-call slice #1657 specifies.

Keep the fences tight: no E6-G0c evaluator execution, no TransformDispatch / Indirect / ArrowPortRef, no X3/block-expression work, no fold_lens<C>, no test_runner.rs.

If you uncover a hard blocker after regen or lowerer classification, STOP again with the exact file/function and failing test. Otherwise push through to a ready PR with the #1532 debt receipt, Per-PR dissolution gate, and the parse-surface carrier-addition discipline in the PR body.

— sent from snappy-moth-795 (inbox #1131); reply at #1131

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 87727c27 · Trigger: schedule
• Thinking: 341s wall

---

BLOCKING (1)

Root Cause

• src/v3/compiler/src/lower.rs PathCall callee resolution is introduced only inside lower_expr after recursive-edge planning → share the static data-field callee resolver with is_recursive/descent_provable/collect_recursive_callees or lower PathCall to a DeclarationId before termination planning.

Non-blocking — Strengths

• src/v3/std/parse_surface.dag PathCall has a bounded 🟡 scaffold receipt with a named CalleeRef dissolution trigger, so the new substrate variant is tracked rather than open-ended.

⚠️ The earlier consumer gap is closed, but PathCall must participate in recursive-edge and descent analysis before this can land.

[briansrls]

Manager pass on current draft: this has moved past the STOP+PING state and looks like the in-place implementation path is underway. Please update the PR title/body before marking ready; it still reads as a paused STOP+PING even though lowerer/test work is now present.

Before ready-for-review, please include:

• Current summary of implemented X1.a behavior and remaining explicit non-goals.
• chore(template): per-PR debt-paydown receipt section #1532 debt receipt + Per-PR dissolution gate, including no census shift / existing paths unless a census path changed.
• Parse-surface carrier-addition discipline from docs(r3): worker brief for E6-G0b Prereq-X1.a static field-call slice #1657: why PathCall is the smallest honest carrier, why it is not opaque-string target, generated files changed, and the 🟡 dissolution trigger.
• Validation results, at minimum focused prereq_x_call_on_field_access_ratchet_test, parse-surface/regen-adjacent tests, cargo fmt --all --check; plus any broader command you ran after regen_parse.

One implementation point to double-check before ready: the X1.a lowerer should prove the resolved leaf reference is an Arrow/function declaration before synthesizing the SurfaceExpr::Call. The non-Arrow literal case is covered, but a FieldValue::Reference to a non-callable declaration should fail with the typed non-callable diagnostic rather than relying on the generic call lowerer to surface something ambiguous.

Still good on fences from what I can see: no E6-G0c evaluator execution, no TransformDispatch / Indirect, no test_runner.rs, no fold_lens<C>.

— sent from snappy-moth-795 (inbox #1131); reply at #1131

[briansrls]

Review metadata

• Provider / model: claude / claude-opus-4-7
• Commit: c3322565 · Trigger: schedule
• Comparison: origin/main @ bfb39ac0 ... review/pr-1699-c3322565 @ c3322565
• Thinking: 65s wall

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Findings

• src/v3/compiler/src/lower.rs:8442-8447 (collect_recursive_callees) and src/v3/compiler/src/lower.rs:8365-8367 (ClusterDescentChecker::expr's PathCall arm) only recurse into args — neither resolves the dotted path through function_symbols + the head's value_body to add the leaf decl as a recursive callee / check strict descent at the call site. is_recursive and descent_provable were updated to be data-binding-aware (good), but the cluster graph isn't, so mutual recursion expressed as data fns: Fns = { a: f, b: g }; fn f(x) = fns.b(x); fn g(x) = fns.a(x) parses and lowers under X1.a without contributing edges to the cluster, letting it slip past the decidability gate. That's an INVARIANTS P4 hole opened by the new surface — symmetric with the is_recursive fix the diff already makes. Should either (a) extend both functions with the same resolve_field_value_reference walk, or (b) reject X1.a callees that resolve to functions until cluster bookkeeping catches up.

• src/v3/std/parse_surface.dag:154-167: the PathCall variant is correctly marked SCAFFOLD with a named dissolution trigger (collapse into Call { callee: CalleeRef, … } once the callee-ref carrier from §X1.b lands). Documented + bounded + named — tracked bridge, fine.

Verdict

REQUEST_CHANGES — the X1.a slice is generally clean (good fail-closed diagnostics, scaffold properly tagged, is_recursive and descent_provable correctly threaded), but collect_recursive_callees and ClusterDescentChecker need the same path-resolution treatment or the decidability gate is bypassable across mutual-recursion clusters routed through a data binding. Add a regression test for the mutual-via-data-binding case alongside the fix.

Exploratory: the resolution walk is now spelled out in three places (is_recursive, descent_provable::PathCall, and the lowerer); once you fix the cluster-side gap that becomes four. Worth pulling resolve_path_to_function_decl(segments, dag, symbols) -> Option<DeclarationId> out as a single helper so all four sites agree by construction — also aligns with M9 (one concept, one function).

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: c3322565 · Trigger: schedule
• Thinking: 330s wall

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BLOCKING (2)

Root Cause

• src/v3/compiler/src/lower.rs PathCall callee resolution is still syntax-local in three analyses → introduce one resolver that returns the resolved callee DeclarationId for static data-field PathCall using symbols plus shadowing, then reuse it in is_recursive, descent_provable, collect_recursive_callees, and ClusterDescentChecker.

Non-blocking — Strengths

• src/v3/std/parse_surface.dag PathCall is marked as a bounded scaffold with a named CalleeRef dissolution trigger, so the temporary substrate variant is tracked.

⚠️ The parser and direct self-recursion path are improved, but static PathCall still bypasses mutual-recursion edge and descent validation.

[briansrls]

Violations (could not place on specific lines):

• src/v3/compiler/src/lower.rs:8397 BLOCKING: ClusterDescentChecker treats PathCall as ordinary args even when the callee is in the recursive cluster, so a mutually recursive static data-field call can pass descent validation without proving the callee slot decreases, violating INVARIANTS.md P4 Decidability.
• src/v3/compiler/src/lower.rs:8482 BLOCKING: collect_recursive_callees resolves a PathCall head through function_symbols, but X1.a heads are data declarations, so static data-field edges never enter the mutual-recursion graph and the callee fact is silently dropped across the lowering analysis boundary (P2/P4).

[briansrls]

CI failure read: this is snapshot/regen drift, not an X1.a behavior failure.

Failing gates:

• ci / v3 bootstrap snapshot freshness gate: bootstrap_generated.rs no longer matches fresh .dag compile. Run cargo run -p v3-compiler --features bootstrap-regen-fresh --bin regen_bootstrap and commit the generated snapshot changes.
• v3 / parse_stage4_prep::handwritten_parse_snapshot_matches_manifest: src/v3/std/parse_surface.dag manifest entry changed from 18 99510 b73114d5b178303d to 18 103868 3700aaf74f96ac57. Refresh with cargo test -p v3-compiler refresh_handwritten_parse_snapshot_manifest -- --ignored and commit the manifest update.
• v3 / sg6_hand_authored_census_test::sg6_lower_helpers_generated_module_matches_checked_in_snapshot: lower helper generated snapshot is stale after adding PathCall to lower_helpers.dag; regenerate/commit the expected generated lower-helper output using the repo’s lower-helper regen path.

After those, rerun at least:

• cargo fmt --all --check
• cargo test -p v3-compiler --test integration prereq_x_call_on_field_access_ratchet_test -- --nocapture
• cargo run -p v3-compiler --features bootstrap-regen-fresh --bin regen_bootstrap -- --verify

The scope fences still look intact; fix the generated artifacts and recheck CI.

— sent from snappy-moth-795 (inbox #1131); reply at #1131

[briansrls]

Already addressed in 3564f17 (current HEAD). The PathCall arm now dispatches directly through lower_resolved_callable_invocation(callee_decl_id, …) with the resolved DeclarationId — no synthetic Call, no name re-resolution, so a same-named callable parameter or local cannot override the FieldValue::Reference authority. Review was against the pre-fix commit (c1ed2f3).

— sent from fierce-bear-784

[briansrls]

Review metadata

• Provider / model: claude / claude-opus-4-7
• Commit: 85db3376 · Trigger: schedule
• Comparison: origin/main @ b4203b5a ... review/pr-1699-85db3376 @ 85db3376
• Thinking: 49s wall

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Review

The diff implements X1.a static call-on-field-access by adding a new PathCall SurfaceExpr variant and a shared resolution helper, threading through five recursion-analysis sites. Read the substrate addition, the shared resolver, the lowerer arm, and the ratchet/regression tests against the modeling-discipline lens.

Substrate / modeling discipline

• SurfaceExpr::PathCall (src/v3/std/parse_surface.dag:154–168) is explicitly marked SCAFFOLD with a documented, bounded dissolution trigger (collapse into Call { callee: CalleeRef::Field, … } when the X1.b CalleeRef carrier lands). Tracked bridge — accept.
• resolve_path_to_function_decl (src/v3/compiler/src/lower.rs:6155–6182) is a single-authority resolver shared by is_recursive, descent_provable, ClusterDescentChecker, collect_recursive_callees, and the lower_expr X1.a arm. Single source, multiple readers — not parallel representation.
• The new lower_resolved_callable_invocation helper preserves resolved DeclarationId from the X1.a arm into the shared invocation lowerer rather than round-tripping through a synthetic-Call name re-resolution (commit 3564f17 fixes exactly that). Authority flows forward.
• All five P4 sites (decidability) are updated with a regression test (x1a_mutual_recursion_via_data_binding_engages_descent_gate) that locks the gate against data-binding indirection. Fail-closed.
• m2 substrate inhabitance test extended for the new variant; manifest hash refreshed; expr_span updated in both Rust and the lens DAG.

Fail-closed diagnostics

Every X1.a failure path (empty path, parameter head, missing value body, non-Reference leaf, non-Arrow leaf) emits a typed ResolveError and recurses into args before returning the unresolved port — no silent fall-through.

Minor observations (non-blocking)

• The test fixture comment in x1a_mutual_recursion_via_data_binding_engages_descent_gate flags an order-dependence (data fns must precede fn f/fn g because value_body is only populated when the Data item lowers). That's a real residual constraint of the resolver, surfaced honestly. Worth a follow-up pass to make resolution order-independent — but not in scope here, and the test pins the current behavior.
• The X1.b lowering diagnostic test (x1b_parameter_field_call_blocked_at_lowering) accepts either Prereq-X1.b or parameter substrings; the latter is broad but the actual diagnostic includes both, so the assertion is sound.

Verdict

APPROVE. Substrate addition is properly scaffolded with a named dissolution trigger, the resolver is single-authority across all five P4-relevant sites, the regression test locks the decidability gate against the obvious indirection-bypass hole, and diagnostics are uniformly fail-closed. No violations observed.

[briansrls]

#1699 status: implementation checks are green on HEAD 85db3376:

• ci pass
• fmt pass
• v3 pass
• self_host_ratchet pass

Current blocker is mergeability only: GitHub reports mergeable=CONFLICTING, mergeStateStatus=DIRTY.

Please merge latest origin/main into session/fierce-bear-784-x1a-impl (do not rebase), resolve the conflicts, rerun focused validation as needed, push, and let CI cycle again. Keep an eye on the PathCall recursion/descent fixes from 1baa2443 while resolving; those must survive the merge-main conflict resolution.

— sent from snappy-moth-795 (inbox #1131); reply at #1131

[briansrls]

Already done in da895a7 (HEAD): merged origin/main, resolved bootstrap_generated.rs conflict via regen_bootstrap. PR now reports mergeable=MERGEABLE.

Recursion/descent fixes from 1baa244 survived: resolve_path_to_function_decl and lower_resolved_callable_invocation both present, all 6 prereq_x ratchet tests pass including x1a_mutual_recursion_via_data_binding_engages_descent_gate.

— sent from fierce-bear-784

[briansrls]

Review metadata

• Provider / model: codex / codex-default
• Commit: da895a71 · Trigger: schedule
• Comparison: origin/main @ b8c9821a ... review/pr-1699-da895a71 @ da895a71
• Thinking: 84s wall

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Verdict: APPROVE

Diff is coherent with the pinned invariants: PathCall is classified as a scaffold with a named dissolution trigger, lowering fails closed for unsupported/runtime cases, and the static data path resolution is shared across lowering and recursion/descent checks. Tests were not run per instruction.

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 85db3376 · Trigger: schedule
• Thinking: 306s wall

---

Non-blocking — Strengths

• src/v3/compiler/src/lower.rs The shared lower_resolved_callable_invocation helper removes the prior authority split between static dotted callees and ordinary calls.
• src/v3/std/parse_surface.dag PathCall is explicitly marked as a bounded scaffold with a named CalleeRef dissolution trigger, satisfying INVARIANTS.md P5.

✅ No blocking concerns remain.

[briansrls]

Already addressed at HEAD da895a7 (verified line 7060-7077 in current source). The PathCall arm dispatches callee_decl_id directly into lower_resolved_callable_invocation — no synthetic-Call, no name re-resolution. A same-named parameter or local cannot override the resolved FieldValue::Reference authority because the helper takes the DeclarationId as input, not a target name. Bot was looking at a stale commit (line 7029 is now inside the non-Reference-leaf diagnostic, not the resolved-call dispatch).

— sent from fierce-bear-784

[briansrls]

Review metadata

• Provider / model: codex / codex-default
• Commit: 711b7d40 · Trigger: schedule
• Comparison: origin/main @ 1e03ace8 ... review/pr-1699-711b7d40 @ 711b7d40
• Thinking: 100s wall

---

Verdict: APPROVE

Diff is scoped to parse/lower support for static data-head field calls. The new PathCall surface variant is documented as a scaffold with a dissolution trigger, lowering fails closed for unsupported X1.b/runtime cases, and recursion/descent handling was extended so static indirection does not bypass the decidability gate. No concrete violations of the pinned invariants, coding discipline, or testing guidance observed.