[Hessesian]

Stacked on #334. Review and merge that first; this PR's diff is only the commit on top.

Bug

resolve_declared_type_from_cst was the one scope-aware declared-type lookup, used for when subjects. It searched a statement list in any order and only read annotations (plus Boolean literals), so:

fun handle(value: Color) {
    when (value) { Color.RED -> {} }   // reported: missing SMALL, LARGE
    val value: Size = Size.SMALL       // declared after the when, still won
}

fun other(value: Color) {}
fun handle() {
    val value = pick()                 // pick(): Size
    when (value) { Size.SMALL -> {} }  // reported: missing RED, GREEN, BLUE
}

The same applied to the root of a field-chain subject (when (holder.shade)).

Fix

• cst_symbol::local_binding_of(name, point, bytes): the by-name-at-a-point form of local_binding_at from fix(resolve): type an identifier from the declaration that binds it at that node #334, for callers that hold a name and a position rather than the identifier node. local_binding_at now delegates to it.
• expr_type::infer_local_type_at(name, point, ..): the type that binding states, with the file it was written in.
• fill_when::analyze_when and resolver::infer::infer_field_chain_type ask it, then fall back to the same by-name lookups as before.
• resolve_declared_type_from_cst (116 lines) is deleted. It had exactly these two callers.

One deliberate behaviour change beyond scoping: an unannotated subject now carries the file its type was written in, and analyze_when uses that file to resolve the type's members, as it already did for field chains.

Tests

Three new diagnostics tests in fill_when_tests.rs, all red before the change with the wrong enum's branches in the message: later-declared local, unannotated local with a same-named parameter in another function, and field-chain root. Existing Boolean-literal and nullable-subject tests still pass through the new path.

RUSTFLAGS="-D warnings" cargo test: 2073 unit tests + integration suites pass. cargo clippy --all-targets -- -D warnings clean.

Not measured

No Moneta run: resolution-accuracy exercises classify_cursor + resolve_identity, not when diagnostics, so it would not see this change. Cost is one scope climb per when expression.

Merge-order note

This removes one resolver::infer:: reach from src/features/fill_when.rs. If #333 (the ratchet) merges first, its resolver::infer:: baseline must drop from 7 to 6 when this is rebased; the test will say so.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Field-chain inference discards the newly available origin URL and can still select an unrelated homonymous root type.

3 open findings

• Preserve inferred binding origin when resolving unannotated chain roots · New
• Correct comment for origin-preserving inferred subjects · New
• Rename abbreviated idx variable to indexer · New

What changed in this PR

Fixes when subject inference to use the local binding in scope at the expression.

Changes:

• Adds scope-aware local type inference with origin tracking.
• Updates plain and field-chain when subjects to use it.
• Adds regression tests for shadowed and inferred locals.

File	Description
src/​resolver/​infer.rs	Uses scoped binding inference for chain roots.
src/​indexer/​infer/​expr_type.rs	Adds infer_local_type_at.
src/​indexer/​infer/​cst_symbol.rs	Adds by-name binding lookup at a CST node.
src/​indexer.rs	Re-exports the new inference helper.
src/​features/​fill_when.rs	Uses scope-aware subject type inference.
src/​features/​fill_when_tests.rs	Adds diagnostic regressions.
AGENTS.md	Documents the new helper.

🧠 Review effort: Balanced

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