test: require direct HIR lowering in dual-path corpus

Author: olwang

crates/rsscript-sdk/tests/mir_migration.rs

@@ -1,9 +1,9 @@
 //! Reusable migration gate for the typed MIR rollout.
 //!
 //! Add a capability by declaring its stage and a small source case. A
-//! `DualPath` case must compile to verified MIR and produce the same result in
-//! the legacy VM, the feature-gated MIR reference interpreter, and the
-//! verified-bytecode VM emitted directly from MIR.
+//! `DualPath` case must lower directly from checked HIR to verified MIR and
+//! produce the same result in the legacy VM, the feature-gated MIR reference
+//! interpreter, and the verified-bytecode VM emitted directly from MIR.
 
 use rsscript_abi_model::WireType;
 use rsscript_compiler::{compile_source_to_ir, compile_validated_to_ir};
@@ -186,9 +186,9 @@ fn dual_path_cases_match_the_legacy_vm() {
                     case.name, case.capability
                 )
             });
-        let mir = compiled.mir().unwrap_or_else(|error| {
+        let mir = compiled.checked_hir_mir().unwrap_or_else(|error| {
             panic!(
-                "{} must lower to MIR during dual-path migration: {error}",
+                "{} must lower directly from checked HIR during dual-path migration: {error}",
                 case.name
             )
         });

docs/architecture/migration-baseline.md

@@ -388,9 +388,10 @@ mechanical acceptance condition holds.
   - [ ] **M05.1 — Add pure-control-flow differential fixtures.** Compare return
     values, errors, and usage reports.
     - [x] **M05.1a — Establish the dual-path harness.** Declarative capability
-      stages and pure-control-flow fixtures compile, verify, execute through the
-      test-only MIR reference interpreter, and compare return values with the
-      legacy VM.
+      stages and pure-control-flow fixtures lower directly from checked HIR,
+      verify, execute through the test-only MIR reference interpreter, and
+      compare return values with the legacy VM. A DualPath fixture cannot hide
+      a fallback through `ExecutableIr`.
     - [x] **M05.1b — Close the initial MIR/VM bytecode loop.** The same scalar,
       CFG, direct-call, `read`, `mut`, and `take` fixtures now compile MIR
       directly to a bytecode artifact, pass the ordinary bytecode verifier, and