diff --git a/crates/ail/tests/typeclass_22b3.rs b/crates/ail/tests/typeclass_22b3.rs
index 4b116ea..e10d1ae 100644
--- a/crates/ail/tests/typeclass_22b3.rs
+++ b/crates/ail/tests/typeclass_22b3.rs
@@ -687,3 +687,110 @@ fn rewrite_replaces_class_method_var_with_mono_symbol_same_module() {
     };
     assert_eq!(callee_name, "show__Int");
 }
+
+/// Helper: build & run a workspace via `ail run` and capture stdout
+/// + stderr. The 22b.3 e2e tests below all funnel through this so the
+/// failure-mode reporting is uniform.
+fn ail_run(fixture_name: &str) -> (std::process::Output, String) {
+    let manifest_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    let ail_bin = std::env::var("CARGO_BIN_EXE_ail")
+        .expect("CARGO_BIN_EXE_ail set by cargo test");
+    let fixture = examples_dir().join(fixture_name);
+
+    let tmp = manifest_dir.join("target").join(format!(
+        "test_22b3_e2e_{}_{}",
+        fixture_name.replace('.', "_"),
+        std::process::id()
+    ));
+    std::fs::create_dir_all(&tmp).expect("mkdir temp");
+
+    let output = std::process::Command::new(&ail_bin)
+        .arg("run")
+        .arg(&fixture)
+        .current_dir(&tmp)
+        .output()
+        .expect("ail run");
+    let stdout = String::from_utf8_lossy(&output.stdout).to_string();
+    (output, stdout)
+}
+
+/// Property: when a single workspace declares two distinct instances of
+/// the SAME class (`R Int` and `R Bool`), and `main` calls the class
+/// method `r` at BOTH types, the binary picks the correct
+/// monomorphised body for each call site. Coherence is preserved
+/// end-to-end: instance `R Int { r _ = 11 }` reaches the `r 0` call,
+/// instance `R Bool { r _ = 22 }` reaches the `r True` call. A
+/// regression where coherence collapses (e.g. both call sites get
+/// rewritten to the same `r__<X>`, or one synth body shadows the other)
+/// would surface here as `11\n11\n`, `22\n22\n`, or build/runtime
+/// failure — all observable at stdout. Defends mono-pass invariant 3.
+#[test]
+fn coherence_two_instances_pick_correct_body_at_runtime() {
+    let (output, stdout) = ail_run("test_22b3_coherence_two_instances.ail.json");
+    assert!(
+        output.status.success(),
+        "ail run failed: stdout={}, stderr={}",
+        stdout,
+        String::from_utf8_lossy(&output.stderr),
+    );
+    assert_eq!(
+        stdout.trim_end_matches('\n'),
+        "11\n22",
+        "stdout = `{stdout}`, stderr = `{}`",
+        String::from_utf8_lossy(&output.stderr),
+    );
+}
+
+/// Property: a class method whose body comes from the class-level
+/// `default` clause (the instance omits the override) is reachable
+/// end-to-end through codegen and run. `class D a where dval : (a) ->
+/// Int default \x. 99` + empty `instance D Int {}` + `main` calling
+/// `dval 0` must produce `99\n`. Currently only `synthesise_mono_fn`'s
+/// unit test covers the default-fallback branch; this fixture pins
+/// down the *binary-level* property — the synthesised fn must lower
+/// and link, the call site must be rewritten to `dval__Int`, the
+/// constant 99 must reach stdout. Defends mono-pass invariant 4.
+#[test]
+fn class_default_method_runs_and_prints_default_value() {
+    let (output, stdout) = ail_run("test_22b3_default_e2e.ail.json");
+    assert!(
+        output.status.success(),
+        "ail run failed: stdout={}, stderr={}",
+        stdout,
+        String::from_utf8_lossy(&output.stderr),
+    );
+    assert_eq!(
+        stdout.trim_end(),
+        "99",
+        "stdout = `{stdout}`, stderr = `{}`",
+        String::from_utf8_lossy(&output.stderr),
+    );
+}
+
+/// Property: a class+instance declared in module A, called from module
+/// B's `main`, links and runs end-to-end. The mono pass appends the
+/// synthesised fn to module A (the instance's defining module), the
+/// call-site rewrite in module B emits the qualified name
+/// `<A>.<mono_symbol>`, and the linker resolves the reference across
+/// module boundaries. The AST-level property is already protected by
+/// `rewrite_uses_qualified_name_for_cross_module_call_site`, but the
+/// emit + link + run path is otherwise untested at the binary level.
+/// A regression that left the synthesised fn unemitted or the call
+/// site unqualified would surface as a link error or wrong stdout.
+/// Defends mono-pass invariant 6.
+#[test]
+fn cross_module_class_method_runs_and_prints_correct_value() {
+    let (output, stdout) = ail_run("test_22b3_xmod_e2e_main.ail.json");
+    assert!(
+        output.status.success(),
+        "ail run failed: stdout={}, stderr={}",
+        stdout,
+        String::from_utf8_lossy(&output.stderr),
+    );
+    assert_eq!(
+        stdout.trim_end(),
+        "7",
+        "stdout = `{stdout}`, stderr = `{}`",
+        String::from_utf8_lossy(&output.stderr),
+    );
+}
diff --git a/examples/test_22b3_coherence_two_instances.ail.json b/examples/test_22b3_coherence_two_instances.ail.json
new file mode 100644
index 0000000..4b77dfa
--- /dev/null
+++ b/examples/test_22b3_coherence_two_instances.ail.json
@@ -0,0 +1,77 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_22b3_coherence_two_instances",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "class", "name": "R", "param": "a",
+      "methods": [{
+        "name": "r",
+        "type": {
+          "k": "fn", "params": [{ "k": "var", "name": "a" }],
+          "ret": { "k": "con", "name": "Int" }, "effects": []
+        }
+      }]
+    },
+    {
+      "kind": "instance",
+      "class": "R",
+      "type": { "k": "con", "name": "Int" },
+      "methods": [{
+        "name": "r",
+        "body": {
+          "t": "lam",
+          "params": ["x"],
+          "paramTypes": [{ "k": "var", "name": "a" }],
+          "retType": { "k": "con", "name": "Int" },
+          "body": { "t": "lit", "lit": { "kind": "int", "value": 11 } }
+        }
+      }]
+    },
+    {
+      "kind": "instance",
+      "class": "R",
+      "type": { "k": "con", "name": "Bool" },
+      "methods": [{
+        "name": "r",
+        "body": {
+          "t": "lam",
+          "params": ["b"],
+          "paramTypes": [{ "k": "var", "name": "a" }],
+          "retType": { "k": "con", "name": "Int" },
+          "body": { "t": "lit", "lit": { "kind": "int", "value": 22 } }
+        }
+      }]
+    },
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn", "params": [], "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "seq",
+        "lhs": {
+          "t": "do",
+          "op": "io/print_int",
+          "args": [{
+            "t": "app",
+            "fn": { "t": "var", "name": "r" },
+            "args": [{ "t": "lit", "lit": { "kind": "int", "value": 0 } }]
+          }]
+        },
+        "rhs": {
+          "t": "do",
+          "op": "io/print_int",
+          "args": [{
+            "t": "app",
+            "fn": { "t": "var", "name": "r" },
+            "args": [{ "t": "lit", "lit": { "kind": "bool", "value": true } }]
+          }]
+        }
+      }
+    }
+  ]
+}
diff --git a/examples/test_22b3_default_e2e.ail.json b/examples/test_22b3_default_e2e.ail.json
new file mode 100644
index 0000000..67e92c5
--- /dev/null
+++ b/examples/test_22b3_default_e2e.ail.json
@@ -0,0 +1,48 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_22b3_default_e2e",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "class", "name": "D", "param": "a",
+      "methods": [{
+        "name": "dval",
+        "type": {
+          "k": "fn", "params": [{ "k": "var", "name": "a" }],
+          "ret": { "k": "con", "name": "Int" }, "effects": []
+        },
+        "default": {
+          "t": "lam",
+          "params": ["x"],
+          "paramTypes": [{ "k": "var", "name": "a" }],
+          "retType": { "k": "con", "name": "Int" },
+          "body": { "t": "lit", "lit": { "kind": "int", "value": 99 } }
+        }
+      }]
+    },
+    {
+      "kind": "instance",
+      "class": "D",
+      "type": { "k": "con", "name": "Int" },
+      "methods": []
+    },
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn", "params": [], "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "do",
+        "op": "io/print_int",
+        "args": [{
+          "t": "app",
+          "fn": { "t": "var", "name": "dval" },
+          "args": [{ "t": "lit", "lit": { "kind": "int", "value": 0 } }]
+        }]
+      }
+    }
+  ]
+}
diff --git a/examples/test_22b3_xmod_e2e_classmod.ail.json b/examples/test_22b3_xmod_e2e_classmod.ail.json
new file mode 100644
index 0000000..7072912
--- /dev/null
+++ b/examples/test_22b3_xmod_e2e_classmod.ail.json
@@ -0,0 +1,32 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_22b3_xmod_e2e_classmod",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "class", "name": "XR", "param": "a",
+      "methods": [{
+        "name": "xr",
+        "type": {
+          "k": "fn", "params": [{ "k": "var", "name": "a" }],
+          "ret": { "k": "con", "name": "Int" }, "effects": []
+        }
+      }]
+    },
+    {
+      "kind": "instance",
+      "class": "XR",
+      "type": { "k": "con", "name": "Int" },
+      "methods": [{
+        "name": "xr",
+        "body": {
+          "t": "lam",
+          "params": ["x"],
+          "paramTypes": [{ "k": "var", "name": "a" }],
+          "retType": { "k": "con", "name": "Int" },
+          "body": { "t": "lit", "lit": { "kind": "int", "value": 7 } }
+        }
+      }]
+    }
+  ]
+}
diff --git a/examples/test_22b3_xmod_e2e_main.ail.json b/examples/test_22b3_xmod_e2e_main.ail.json
new file mode 100644
index 0000000..985a846
--- /dev/null
+++ b/examples/test_22b3_xmod_e2e_main.ail.json
@@ -0,0 +1,25 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_22b3_xmod_e2e_main",
+  "imports": [{ "module": "test_22b3_xmod_e2e_classmod" }],
+  "defs": [
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn", "params": [], "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "do",
+        "op": "io/print_int",
+        "args": [{
+          "t": "app",
+          "fn": { "t": "var", "name": "xr" },
+          "args": [{ "t": "lit", "lit": { "kind": "int", "value": 0 } }]
+        }]
+      }
+    }
+  ]
+}