diff --git a/packages/compiler/src/frontend/lowering/lower-classes.ts b/packages/compiler/src/frontend/lowering/lower-classes.ts
index 95282f381..80fde36bd 100644
--- a/packages/compiler/src/frontend/lowering/lower-classes.ts
+++ b/packages/compiler/src/frontend/lowering/lower-classes.ts
@@ -7712,6 +7712,24 @@ function paramPropInitStmts(lowerer: Lowerer, info: ClassInfo, thisLocal: IrLoca
   return out;
 }
 
+/** Whether a super() call's value is discarded by its statement: the call
+ * is the expression statement itself, or an operand of a comma chain that
+ * is (`super(m, o), this.code = c;`, as minifiers join statements). The
+ * statement lowering runs each comma operand as its own statement in
+ * source order, so the chain lowers exactly like `super(m, o); this.code =
+ * c;`. Parentheses are transparent to both. */
+function superCallInStatementPosition(call: ts.CallExpression): boolean {
+  let node: ts.Node = call;
+  for (;;) {
+    const parent = node.parent;
+    if (ts.isExpressionStatement(parent)) return true;
+    const comma =
+      ts.isBinaryExpression(parent) && parent.operatorToken.kind === ts.SyntaxKind.CommaToken;
+    if (!comma && !ts.isParenthesizedExpression(parent)) return false;
+    node = parent;
+  }
+}
+
 /** Super statements initialize the base and then the derived fields on
  * whichever control-flow path executes. Repeated calls are explicitly
  * refused until native layouts can allocate a second receiver. */
@@ -7729,7 +7747,7 @@ export function lowerDerivedCtorBody(
   const previousInitialized = context.superInitialized;
   context.superInitialized = initialized;
   context.superCall = (superCall) => {
-    if (!ts.isExpressionStatement(superCall.parent))
+    if (!superCallInStatementPosition(superCall))
       lowerer.unsupported("SC1090", superCall, "super() in an expression position");
     superSeen = true;
     const loc = locOf(superCall);
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-jose-errors.js.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-jose-errors.js.json
new file mode 100644
index 000000000..0ed94bfd7
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-jose-errors.js.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/super-comma-jose-errors.js"
+ ],
+ "diags": []
+}
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-sequence-js.js.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-sequence-js.js.json
new file mode 100644
index 000000000..5698bfbed
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-sequence-js.js.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/super-comma-sequence-js.js"
+ ],
+ "diags": []
+}
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-sequence.ts.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-sequence.ts.json
new file mode 100644
index 000000000..3954c5766
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/super-comma-sequence.ts.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/super-comma-sequence.ts"
+ ],
+ "diags": []
+}
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/diagnostics/super-comma-nested.ts.json b/packages/compiler/test/ts7/baselines/order-parity/tests/diagnostics/super-comma-nested.ts.json
new file mode 100644
index 000000000..558b0ad78
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/diagnostics/super-comma-nested.ts.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/diagnostics/super-comma-nested.ts"
+ ],
+ "diags": []
+}
diff --git a/tests/corpus/super-comma-jose-errors.js b/tests/corpus/super-comma-jose-errors.js
new file mode 100644
index 000000000..a194fca93
--- /dev/null
+++ b/tests/corpus/super-comma-jose-errors.js
@@ -0,0 +1,84 @@
+// jose 6.2.12's error classes (dist/webapi/util/errors.js), verbatim in
+// shape: minifiers join a derived constructor's statements into one comma
+// expression that opens with super(...). Each comma operand runs as its
+// own statement, so the base constructor and the class field initializers
+// finish before the trailing assignments.
+class JOSEError extends Error {
+  static code = "ERR_JOSE_GENERIC";
+  code = "ERR_JOSE_GENERIC";
+  constructor(message, options) {
+    super(message, options), this.name = this.constructor.name, Error.captureStackTrace?.(this, this.constructor);
+  }
+}
+class JWTClaimValidationFailed extends JOSEError {
+  static code = "ERR_JWT_CLAIM_VALIDATION_FAILED";
+  code = "ERR_JWT_CLAIM_VALIDATION_FAILED";
+  claim;
+  reason;
+  payload;
+  constructor(message, payload, claim = "unspecified", reason = "unspecified") {
+    super(message, { cause: { claim, reason, payload } }), this.claim = claim, this.reason = reason, this.payload = payload;
+  }
+}
+class JWTExpired extends JOSEError {
+  static code = "ERR_JWT_EXPIRED";
+  code = "ERR_JWT_EXPIRED";
+  claim;
+  reason;
+  payload;
+  constructor(message, payload, claim = "unspecified", reason = "unspecified") {
+    super(message, { cause: { claim, reason, payload } }), this.claim = claim, this.reason = reason, this.payload = payload;
+  }
+}
+class JOSEAlgNotAllowed extends JOSEError {
+  static code = "ERR_JOSE_ALG_NOT_ALLOWED";
+  code = "ERR_JOSE_ALG_NOT_ALLOWED";
+}
+class JWSSignatureVerificationFailed extends JOSEError {
+  static code = "ERR_JWS_SIGNATURE_VERIFICATION_FAILED";
+  code = "ERR_JWS_SIGNATURE_VERIFICATION_FAILED";
+  constructor(message = "signature verification failed", options) {
+    super(message, options);
+  }
+}
+
+// The stack is read where the receiver's class is known: a read through an
+// untyped parameter does not see the stack (a documented scriptc gap).
+function describe(label, error, stack) {
+  console.log(label, error.name, error.code, JSON.stringify(error.message));
+  console.log("  instanceof", error instanceof JOSEError, error instanceof Error);
+  console.log("  stack head", String(stack).split("\n")[0]);
+}
+
+const generic = new JOSEError("generic failure");
+describe("generic", generic, generic.stack);
+console.log("  static", JOSEError.code, "cause" in generic);
+
+const withCause = new JOSEError("wrapped", { cause: "root" });
+describe("wrapped", withCause, withCause.stack);
+console.log("  cause", withCause.cause);
+
+const claims = { sub: "user", exp: 1 };
+const failed = new JWTClaimValidationFailed('"iss" claim mismatch', claims, "iss", "check_failed");
+describe("claim", failed, failed.stack);
+console.log("  fields", failed.claim, failed.reason, failed.payload === claims);
+console.log("  cause", failed.cause.claim, failed.cause.reason, failed.cause.payload === claims);
+console.log("  chain", failed instanceof JWTClaimValidationFailed, failed instanceof JWTExpired);
+
+const defaults = new JWTClaimValidationFailed("defaults", claims);
+console.log("defaults", defaults.claim, defaults.reason);
+
+const expired = new JWTExpired('"exp" claim timestamp check failed', claims, "exp");
+describe("expired", expired, expired.stack);
+console.log("  static", JWTExpired.code, expired.reason);
+
+const alg = new JOSEAlgNotAllowed('"alg" (Algorithm) Header Parameter value not allowed');
+describe("alg", alg, alg.stack);
+const sig = new JWSSignatureVerificationFailed();
+describe("sig", sig, sig.stack);
+
+try {
+  throw new JWTExpired("thrown", claims, "exp", "check_failed");
+} catch (error) {
+  if (error instanceof JOSEError) console.log("caught", error.name, error.code, error.claim);
+}
diff --git a/tests/corpus/super-comma-sequence-js.js b/tests/corpus/super-comma-sequence-js.js
new file mode 100644
index 000000000..073bcd97d
--- /dev/null
+++ b/tests/corpus/super-comma-sequence-js.js
@@ -0,0 +1,49 @@
+// The JavaScript side of super-comma-sequence.ts: a statement-level comma
+// expression containing super(...) runs its operands in source order, with
+// the base constructor and the derived field initializers at the super()
+// call, as the separate statements a minifier joined would.
+function log(label, value) {
+  console.log("  " + label);
+  return value;
+}
+
+class Base {
+  constructor(origin) {
+    console.log("  Base body", origin);
+    this.origin = origin;
+  }
+}
+
+class Joined extends Base {
+  first = log("field first", 1);
+  second = this.first + 1;
+  constructor(origin) {
+    super(log("super argument", origin)), log("after super", 0), this.tag = `${this.origin}:${this.second}`;
+  }
+}
+
+class Leading extends Base {
+  value = log("field value", "v");
+  constructor(origin) {
+    log("before super", 0), super(origin), log("after super " + this.value, 0);
+  }
+}
+
+class Again extends Joined {
+  extra = log("field extra", "e");
+  constructor() {
+    super("again"), this.tag = this.tag + "!", this.extra = this.extra + this.tag;
+  }
+}
+
+console.log("joined:");
+const joined = new Joined("j");
+console.log(joined.origin, joined.first, joined.second, joined.tag);
+
+console.log("leading:");
+const leading = new Leading("l");
+console.log(leading.origin, leading.value);
+
+console.log("again:");
+const again = new Again();
+console.log(again.origin, again.tag, again.extra, again instanceof Joined, again instanceof Base);
diff --git a/tests/corpus/super-comma-sequence.ts b/tests/corpus/super-comma-sequence.ts
new file mode 100644
index 000000000..46e23a509
--- /dev/null
+++ b/tests/corpus/super-comma-sequence.ts
@@ -0,0 +1,101 @@
+// @transform-types
+// super(...) as an operand of a statement-level comma expression lowers
+// like the separate statements a minifier joined: operands run in source
+// order, the base constructor and then the derived field initializers run
+// at the super() call, and the trailing operands see the initialized
+// instance.
+function log<T>(label: string, value: T): T {
+  console.log("  " + label);
+  return value;
+}
+
+class Base {
+  readonly origin: string;
+  constructor(origin: string) {
+    console.log("  Base body", origin);
+    this.origin = origin;
+  }
+}
+
+class Joined extends Base {
+  first = log("field first", 1);
+  second: number = this.first + 1;
+  tag: string;
+  constructor(origin: string) {
+    super(log("super argument", origin)), log("after super", 0), this.tag = `${this.origin}:${this.second}`;
+  }
+}
+
+class Leading extends Base {
+  value = log("field value", "v");
+  constructor(origin: string) {
+    log("before super", 0), super(origin), log("after super " + this.value, 0);
+  }
+}
+
+class Parenthesized extends Base {
+  count = 0;
+  constructor() {
+    (super("paren"), this.count++, this.count++);
+  }
+}
+
+class Nested extends Base {
+  steps: string[] = [];
+  constructor() {
+    super("nested"), (this.steps.push("a"), this.steps.push("b")), this.steps.push("c");
+  }
+}
+
+class Branching extends Base {
+  side: string;
+  constructor(left: boolean) {
+    if (left) super("left"), this.side = "L";
+    else super("right"), this.side = "R";
+  }
+}
+
+class Point {
+  constructor(
+    public x: number,
+    public y: number,
+  ) {}
+}
+
+class Point3 extends Point {
+  label = "p3";
+  constructor(
+    x: number,
+    y: number,
+    public z: number,
+  ) {
+    super(x, y), console.log("  Point3", this.x, this.y, this.z, this.label);
+  }
+}
+
+class Point4 extends Point3 {
+  w: number;
+  constructor(x: number, y: number, z: number, w: number) {
+    super(x, y, z), this.w = w, this.label = "p4";
+  }
+}
+
+console.log("joined:");
+const joined = new Joined("j");
+console.log(joined.origin, joined.first, joined.second, joined.tag);
+
+console.log("leading:");
+const leading = new Leading("l");
+console.log(leading.origin, leading.value);
+
+const paren = new Parenthesized();
+console.log("parenthesized:", paren.origin, paren.count);
+
+const nested = new Nested();
+console.log("nested:", nested.origin, nested.steps.join(","));
+
+console.log("branching:", new Branching(true).side, new Branching(false).side);
+
+console.log("chain:");
+const p4 = new Point4(1, 2, 3, 4);
+console.log(p4.x, p4.y, p4.z, p4.w, p4.label, p4 instanceof Point3, p4 instanceof Point);
diff --git a/tests/diagnostics/super-comma-nested.ts b/tests/diagnostics/super-comma-nested.ts
new file mode 100644
index 000000000..799436ff9
--- /dev/null
+++ b/tests/diagnostics/super-comma-nested.ts
@@ -0,0 +1,24 @@
+// super(...) as an operand of a statement-level comma expression compiles
+// (super-comma-sequence.ts). Any other expression position still refuses:
+// the field initializers that run at super() would be misordered.
+class Base {
+  constructor(readonly origin: string) {}
+}
+
+class Selected extends Base {
+  constructor(left: boolean) {
+    left ? super("left") : super("right");
+  }
+}
+
+function keep<T>(value: T): T {
+  return value;
+}
+
+class Argument extends Base {
+  constructor() {
+    keep((super("argument"), 1));
+  }
+}
+
+console.log(new Selected(true).origin, new Argument().origin);
diff --git a/tests/harness/__snapshots__/super-comma-nested.ts.txt b/tests/harness/__snapshots__/super-comma-nested.ts.txt
new file mode 100644
index 000000000..e7b7f275a
--- /dev/null
+++ b/tests/harness/__snapshots__/super-comma-nested.ts.txt
@@ -0,0 +1,27 @@
+super-comma-nested.ts:9:3 - error SC1090: derived constructors without a lowered super() call is not supported yet
+
+   8 | class Selected extends Base {
+   9 |   constructor(left: boolean) {
+     |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  10 |     left ? super("left") : super("right");
+
+super-comma-nested.ts:10:12 - error SC1090: super() in an expression position is not supported yet
+
+   9 |   constructor(left: boolean) {
+  10 |     left ? super("left") : super("right");
+     |            ^~~~~~~~~~~~~
+  11 |   }
+
+super-comma-nested.ts:19:3 - error SC1090: derived constructors without a lowered super() call is not supported yet
+
+  18 | class Argument extends Base {
+  19 |   constructor() {
+     |   ^~~~~~~~~~~~~~~
+  20 |     keep((super("argument"), 1));
+
+super-comma-nested.ts:20:11 - error SC1090: super() in an expression position is not supported yet
+
+  19 |   constructor() {
+  20 |     keep((super("argument"), 1));
+     |           ^~~~~~~~~~~~~~~~~
+  21 |   }
\ No newline at end of file