diff --git a/crates/aura-cli/tests/cli_run.rs b/crates/aura-cli/tests/cli_run.rs
index 7d5b084..b1986bc 100644
--- a/crates/aura-cli/tests/cli_run.rs
+++ b/crates/aura-cli/tests/cli_run.rs
@@ -4910,6 +4910,68 @@ fn aura_sweep_synthetic_member_panic_is_contained() {
     let _ = std::fs::remove_dir_all(&cwd);
 }
 
+/// E2E (#278 decision, mc twin): the synthetic `aura mc` shares the same
+/// bare-member seam as its sweep/walkforward siblings (`run_blueprint_member`
+/// inside `blueprint_mc_family`'s per-seed draw closure, no #272 fault
+/// boundary), so the same member-compile fault class must be contained the
+/// same way — one `aura: warning: ` line naming the fault, no raw panic text
+/// or internal `crates/` path on stderr, deliberate exit 3 (C14), never 101.
+/// mc takes only CLOSED blueprints, so the poison is BOUND (`length=0` on the
+/// SMA add-op) rather than a poison axis: the test builds its minimal 4-op
+/// poison blueprint inline via `aura graph build`. Two seeds so the parallel
+/// draws join before the lowest-seed fault resolves (the shipped sweep
+/// contract's thread-order-independent shape, C1).
+#[test]
+fn aura_mc_synthetic_member_panic_is_contained() {
+    let cwd = temp_cwd("blueprint-mc-member-panic-contained");
+    // Minimal poison: each op is load-bearing (source: the close role; add+bind:
+    // the length=0 that trips `Sma::new`'s "SMA length must be >= 1" assert at
+    // member compile; feed: wiring so build validation passes; expose: the bias
+    // contract). Bound length keeps the blueprint CLOSED, as `aura mc` requires.
+    let ops = r#"[
+      {"op":"source","role":"close","kind":"F64"},
+      {"op":"add","type":"SMA","name":"sma","bind":{"length":{"I64":0}}},
+      {"op":"feed","role":"close","into":["sma.series"]},
+      {"op":"expose","from":"sma.value","as":"bias"}
+    ]"#;
+    let ops_path = cwd.join("poison.ops.json");
+    std::fs::write(&ops_path, ops).expect("write poison op-list");
+    let bp_path = cwd.join("poison.bp.json");
+    let build = std::process::Command::new(env!("CARGO_BIN_EXE_aura"))
+        .args(["graph", "build"])
+        .stdin(std::fs::File::open(&ops_path).expect("open poison op-list"))
+        .current_dir(&cwd)
+        .output()
+        .expect("spawn aura graph build (poison blueprint)");
+    assert_eq!(
+        build.status.code(),
+        Some(0),
+        "poison blueprint builds (the fault is a member-COMPILE fault, not a build refusal): {}",
+        String::from_utf8_lossy(&build.stderr)
+    );
+    std::fs::write(&bp_path, &build.stdout).expect("write poison blueprint");
+    let out = std::process::Command::new(env!("CARGO_BIN_EXE_aura"))
+        .args(["mc", bp_path.to_str().expect("utf-8 path"), "--seeds", "2"])
+        .current_dir(&cwd)
+        .output()
+        .expect("spawn aura mc (poison member)");
+    let stderr = String::from_utf8_lossy(&out.stderr).to_string();
+    assert!(
+        stderr.lines().any(|l| l.contains("aura: warning: ") && l.contains("SMA length must be >= 1")),
+        "the member fault surfaces as one class-marked warning naming the fault: {stderr}"
+    );
+    assert!(
+        !stderr.contains("panicked at") && !stderr.contains("crates/"),
+        "no raw panic report or internal source path leaks: {stderr}"
+    );
+    assert_eq!(
+        out.status.code(),
+        Some(3),
+        "a contained member fault is the deliberate failed-cells exit 3, never 101: {stderr}"
+    );
+    let _ = std::fs::remove_dir_all(&cwd);
+}
+
 /// E2E (#313, Path 1 — the real/sugar walk-forward): the degenerate
 /// equal-length config over the shared GER40 archive emits the same
 /// zero-trade note. Gated on the archive; skips cleanly on a data refusal.