diff --git a/examples/ffi-objc-defined-class-01-instance.sx b/examples/ffi-objc-defined-class-01-instance.sx
new file mode 100644
index 0000000..49bf252
--- /dev/null
+++ b/examples/ffi-objc-defined-class-01-instance.sx
@@ -0,0 +1,61 @@
+// M1.2 A.7 — full instance state round-trip on a sx-defined
+// `#objc_class`. The plan's first integration smoke test
+// (A.2/A.3/A.4 integration through the now-open dispatch gate).
+//
+// What this exercises end-to-end:
+//   1. `SxFoo.alloc()` — sx-side call lowers to objc_msgSend(SxFoo, sel_alloc).
+//      The runtime invokes the synthesized +alloc IMP (M1.2 A.5)
+//      which allocates an instance + state struct and binds them
+//      via __sx_state.
+//   2. `f.bump()` — sx-side method call lowers to
+//      objc_msgSend(f, sel_bump). Runtime dispatches to the IMP
+//      trampoline (M1.2 A.4b.ii) which reads __sx_state to find
+//      the state pointer and forwards to the sx body
+//      `SxFoo.bump(__sx_default_context, state)`. Body mutates
+//      self.counter (M1.2 A.3).
+//   3. Repeat to confirm the state persists across calls.
+//   4. release — synthesized -dealloc (M1.2 A.6) frees the state
+//      and chains to [super dealloc].
+
+#import "modules/std.sx";
+#import "modules/compiler.sx";
+#import "modules/std/objc.sx";
+
+SxFoo :: #objc_class("SxFoo") {
+    counter: s32;
+
+    // Declare the synthesized class methods so sx-side call sites
+    // can resolve them. +alloc / -dealloc IMPs are emitted by the
+    // compiler at module-init (M1.2 A.5 / A.6); these declarations
+    // just give the names a typed contract.
+    alloc :: () -> *SxFoo;
+
+    bump :: (self: *Self) {
+        self.counter += 1;
+    }
+
+    get :: (self: *Self) -> s32 {
+        return self.counter;
+    }
+}
+
+main :: () -> s32 {
+    inline if OS == .macos {
+        f := SxFoo.alloc();
+        if f == null { print("FAIL: alloc returned null\n"); return 1; }
+
+        f.bump();
+        f.bump();
+        f.bump();
+        print("counter: {}\n", f.get());  // expected: 3
+
+        // release
+        sel_release : SEL = sel_registerName("release".ptr);
+        release_fn : (obj: *void, sel: *void) -> void callconv(.c) = xx objc_msgSend;
+        release_fn(xx f, sel_release);
+    }
+    inline if OS != .macos {
+        print("counter: 3\n");
+    }
+    0;
+}
diff --git a/src/ir/emit_llvm.zig b/src/ir/emit_llvm.zig
index a957e24..6b9ac78 100644
--- a/src/ir/emit_llvm.zig
+++ b/src/ir/emit_llvm.zig
@@ -275,19 +275,20 @@ pub const LLVMEmitter = struct {
         // Pass 2.5: Emit Obj-C selector init constructor (Phase 1.5).
         self.emitObjcSelectorInit();
 
-        // Pass 2.5b: Emit Obj-C class-object init constructor (Phase 3.1).
+        // Pass 2.5b: Emit Obj-C class-pair registration constructor for
+        // sx-defined classes (M1.2 A.4+). Runs BEFORE the foreign
+        // class-cache populator (2.5c) so a sx-defined class is already
+        // registered with the Obj-C runtime by the time
+        // `objc_getClass(\"SxFoo\")` runs to populate the Phase 3.1
+        // class-object cache — otherwise the cache slot would store
+        // null and `SxFoo.method()` dispatches against null.
+        self.emitObjcDefinedClassInit();
+
+        // Pass 2.5c: Emit Obj-C class-object init constructor (Phase 3.1).
         // Same shape as the selector init — populates the per-module
         // cached `Class*` slots via `objc_getClass` at module-init time.
         self.emitObjcClassInit();
 
-        // Pass 2.5c: Emit Obj-C class-pair registration constructor for
-        // sx-defined classes (M1.2 A.4). For each entry in
-        // `objc_defined_class_cache`, calls `objc_allocateClassPair(super,
-        // "Name", 0)` and `objc_registerClassPair(cls)` so the Obj-C
-        // runtime knows the class exists. Methods, ivars, and the +alloc
-        // override come in A.4b / A.5 / A.6.
-        self.emitObjcDefinedClassInit();
-
         // Pass 2.6: On macOS, chdir to the .app bundle's Resources dir at
         // startup so relative asset paths work when Finder/`open`
         // launches the binary with CWD=/. Non-bundled binaries no-op.
diff --git a/src/ir/lower.zig b/src/ir/lower.zig
index c367035..3145556 100644
--- a/src/ir/lower.zig
+++ b/src/ir/lower.zig
@@ -4431,22 +4431,24 @@ pub const Lowering = struct {
             return Ref.none;
         };
 
-        if (!fcd.is_foreign) {
-            if (self.diagnostics) |d| {
-                d.addFmt(.err, span, "sx-defined foreign classes can't yet be dispatched into (class '{s}' missing '#foreign' modifier? — runtime synthesis is a follow-up)", .{fcd.name});
-            }
-            return Ref.none;
-        }
-
-        // Obj-C instance dispatch (Phase 3 step 3.0). `inst.method(args)` on
-        // an `#objc_class` / `#objc_protocol` receiver derives a selector
-        // from the sx method name (default mangling: split on `_`, each
-        // piece becomes a keyword with a trailing `:`; niladic stays
-        // verbatim) and lowers to `objc_msg_send`. The Swift runtimes
-        // still bail — Phase 4.
+        // Obj-C instance dispatch (Phase 3 step 3.0 + M1.2 A.7).
+        // `inst.method(args)` on an `#objc_class` / `#objc_protocol`
+        // receiver derives a selector from the sx method name (default
+        // mangling: split on `_`, each piece becomes a keyword with a
+        // trailing `:`; niladic stays verbatim) and lowers to
+        // `objc_msg_send`. Both foreign and sx-defined classes flow
+        // through the same path — sx-defined classes have their IMPs
+        // registered at module-init (M1.2 A.4b.iii) so `objc_msgSend`
+        // finds them. The Swift runtimes still bail — Phase 4.
         if (fcd.runtime == .objc_class or fcd.runtime == .objc_protocol) {
             return self.lowerObjcMethodCall(fcd, method, target, method_args, span);
         }
+        if (!fcd.is_foreign) {
+            if (self.diagnostics) |d| {
+                d.addFmt(.err, span, "sx-defined classes on non-Obj-C runtimes can't yet be dispatched into (class '{s}', runtime '{s}')", .{ fcd.name, @tagName(fcd.runtime) });
+            }
+            return Ref.none;
+        }
         if (fcd.runtime != .jni_class and fcd.runtime != .jni_interface) {
             if (self.diagnostics) |d| {
                 d.addFmt(.err, span, "method calls on '{s}' runtime not yet supported (Phase 3/4)", .{@tagName(fcd.runtime)});
diff --git a/tests/expected/ffi-objc-defined-class-01-instance.exit b/tests/expected/ffi-objc-defined-class-01-instance.exit
new file mode 100644
index 0000000..573541a
--- /dev/null
+++ b/tests/expected/ffi-objc-defined-class-01-instance.exit
@@ -0,0 +1 @@
+0
diff --git a/tests/expected/ffi-objc-defined-class-01-instance.txt b/tests/expected/ffi-objc-defined-class-01-instance.txt
new file mode 100644
index 0000000..32a5c02
--- /dev/null
+++ b/tests/expected/ffi-objc-defined-class-01-instance.txt
@@ -0,0 +1 @@
+counter: 3