[ubelai]

Fixes #1445

Summary

Closes three HYB-E3104 (T24 / O8 / O2 LOAN-ESCAPE) soundness and buildable-Go gaps on map-slot loans (n := &m[k]):

1. compiler/crates/hy-check/src/addr_loan.rs (walk_addr_of_loan_projections, line 337):
   • Match Expr::Field { .. } | Expr::Index { .. } (matching the existing docstring at addr_loan.rs:153-156) so taking the address of an array or slice index projection rooted at a map-slot loan (&n.arr[0], &n.fixed[0]) is rejected with HYB-E3104 (T24).
2. compiler/crates/hy-check/src/emit_guard.rs (check_stmt_emit_guard_inner, line 156):
   • Invoke self.check_slot_loan_rebind(st, stmt) before self.mark_slot_loans_assign(st, targets, *op, values) when deep == true so re-binding a closure-local map-slot loan to a general pointer (s = &other) or nil (s = nil) is rejected with HYB-E3104 (T24), matching top-level check_fn_body.
3. compiler/crates/hy-check/src/closures.rs (check_one_closure, line 217):
   • Propagate borrow_bindings: st.borrow_bindings.clone() into cst so returning a captured borrow or map-slot loan from a nested closure is rejected with HYB-E3104 (O2 LOAN-ESCAPE).
4. Regression Tests (compiler/crates/hy-check/src/closures.rs):
   • reject_addr_of_index_projection_on_slot_loan_t24
   • reject_closure_slot_loan_rebind_to_general_pointer_or_nil_t24
   • All 175/175 hy-check unit tests + 65/65 integration test suites (240/240 total) pass with 0 failures.

Payout wallet (EVM / USDC): 0x1d74c4F8655ca2b7BCA7D41C60320ebB23990eA3

[github-actions]

Shepherd (Phase A — propose only): this PR's changed-file set overlaps >=0.6 Jaccard with #1790, which carries the larger take. Proposing close as superseded.

This is a proposal, not a close — nothing auto-closes while this comment is fresh. If this PR has unique content (a different rule, extra tests, a different fix), say so or push, and the label comes off. Cluster signal is a file-set heuristic; the verdict stays human.