From 32757fa15a9a96e3cfb15915899ffddeead25f01 Mon Sep 17 00:00:00 2001
From: Huanyi Xie <74809554+xiehuanyi@users.noreply.github.com>
Date: Sun, 11 Oct 2026 21:01:57 +0300
Subject: [PATCH 1/2] fix(stream-transform): honor falsy params in the sync API

---
 packages/stream-transform/dist/cjs/sync.cjs |  2 +-
 packages/stream-transform/dist/esm/sync.js  |  2 +-
 packages/stream-transform/dist/iife/sync.js |  2 +-
 packages/stream-transform/dist/umd/sync.js  |  2 +-
 packages/stream-transform/lib/sync.js       |  2 +-
 packages/stream-transform/test/api.sync.js  | 21 +++++++++++++++++++++
 6 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/packages/stream-transform/dist/cjs/sync.cjs b/packages/stream-transform/dist/cjs/sync.cjs
index 360c0e9b6..a495fd454 100644
--- a/packages/stream-transform/dist/cjs/sync.cjs
+++ b/packages/stream-transform/dist/cjs/sync.cjs
@@ -145,7 +145,7 @@ const transform = function () {
   }
   // Validate arguments
   let expected_handler_length = 1;
-  if (options.params) {
+  if (options.params !== undefined && options.params !== null) {
     expected_handler_length++;
   }
   if (handler.length > expected_handler_length) {
diff --git a/packages/stream-transform/dist/esm/sync.js b/packages/stream-transform/dist/esm/sync.js
index aeb8d90ab..886c81724 100644
--- a/packages/stream-transform/dist/esm/sync.js
+++ b/packages/stream-transform/dist/esm/sync.js
@@ -5263,7 +5263,7 @@ const transform = function () {
   }
   // Validate arguments
   let expected_handler_length = 1;
-  if (options.params) {
+  if (options.params !== undefined && options.params !== null) {
     expected_handler_length++;
   }
   if (handler.length > expected_handler_length) {
diff --git a/packages/stream-transform/dist/iife/sync.js b/packages/stream-transform/dist/iife/sync.js
index 60b8c7d94..6113387d8 100644
--- a/packages/stream-transform/dist/iife/sync.js
+++ b/packages/stream-transform/dist/iife/sync.js
@@ -5266,7 +5266,7 @@ var stream_transform_sync = (function (exports) {
     }
     // Validate arguments
     let expected_handler_length = 1;
-    if (options.params) {
+    if (options.params !== undefined && options.params !== null) {
       expected_handler_length++;
     }
     if (handler.length > expected_handler_length) {
diff --git a/packages/stream-transform/dist/umd/sync.js b/packages/stream-transform/dist/umd/sync.js
index 8eb2a88b5..d6cf8f07f 100644
--- a/packages/stream-transform/dist/umd/sync.js
+++ b/packages/stream-transform/dist/umd/sync.js
@@ -5269,7 +5269,7 @@
     }
     // Validate arguments
     let expected_handler_length = 1;
-    if (options.params) {
+    if (options.params !== undefined && options.params !== null) {
       expected_handler_length++;
     }
     if (handler.length > expected_handler_length) {
diff --git a/packages/stream-transform/lib/sync.js b/packages/stream-transform/lib/sync.js
index e09e75130..67b2cfc69 100644
--- a/packages/stream-transform/lib/sync.js
+++ b/packages/stream-transform/lib/sync.js
@@ -33,7 +33,7 @@ const transform = function () {
   }
   // Validate arguments
   let expected_handler_length = 1;
-  if (options.params) {
+  if (options.params !== undefined && options.params !== null) {
     expected_handler_length++;
   }
   if (handler.length > expected_handler_length) {
diff --git a/packages/stream-transform/test/api.sync.js b/packages/stream-transform/test/api.sync.js
index f9b365747..88234f151 100644
--- a/packages/stream-transform/test/api.sync.js
+++ b/packages/stream-transform/test/api.sync.js
@@ -31,6 +31,27 @@ describe("api.sync", function () {
     data.should.eql(["a|b|c", "1|2|3"]);
   });
 
+  for (const params of [0, false, ""]) {
+    it(`honors falsy params ${JSON.stringify(params)}`, function () {
+      const data = transform(["record"], { params }, function (record, value) {
+        return [record, value];
+      });
+      data.should.eql([["record", params]]);
+    });
+  }
+
+  for (const params of [undefined, null]) {
+    it(`rejects callback handlers with params ${params}`, function () {
+      (function () {
+        transform(["record"], { params }, function (record, callback) {
+          callback(null, record);
+        });
+      }).should.throw(
+        "Invalid Handler: only synchronous handlers are supported",
+      );
+    });
+  }
+
   it("only sync handlers are supported", function () {
     // Without options
     (function () {

From 7b0f5a0fae0161c92ab624a3152353f7711b32e7 Mon Sep 17 00:00:00 2001
From: Huanyi Xie <74809554+xiehuanyi@users.noreply.github.com>
Date: Mon, 12 Oct 2026 01:29:22 +0300
Subject: [PATCH 2/2] test(stream-transform): group sync params regressions
 with option tests

---
 packages/stream-transform/test/api.sync.js    | 21 --------------
 .../stream-transform/test/option.params.js    | 29 +++++++++++++++++++
 2 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/packages/stream-transform/test/api.sync.js b/packages/stream-transform/test/api.sync.js
index 88234f151..f9b365747 100644
--- a/packages/stream-transform/test/api.sync.js
+++ b/packages/stream-transform/test/api.sync.js
@@ -31,27 +31,6 @@ describe("api.sync", function () {
     data.should.eql(["a|b|c", "1|2|3"]);
   });
 
-  for (const params of [0, false, ""]) {
-    it(`honors falsy params ${JSON.stringify(params)}`, function () {
-      const data = transform(["record"], { params }, function (record, value) {
-        return [record, value];
-      });
-      data.should.eql([["record", params]]);
-    });
-  }
-
-  for (const params of [undefined, null]) {
-    it(`rejects callback handlers with params ${params}`, function () {
-      (function () {
-        transform(["record"], { params }, function (record, callback) {
-          callback(null, record);
-        });
-      }).should.throw(
-        "Invalid Handler: only synchronous handlers are supported",
-      );
-    });
-  }
-
   it("only sync handlers are supported", function () {
     // Without options
     (function () {
diff --git a/packages/stream-transform/test/option.params.js b/packages/stream-transform/test/option.params.js
index 17579d9af..4474cf75b 100644
--- a/packages/stream-transform/test/option.params.js
+++ b/packages/stream-transform/test/option.params.js
@@ -1,7 +1,36 @@
+import "should";
+import { transform as transformSync } from "../lib/sync.js";
 import { generate } from "csv-generate";
 import { transform } from "../lib/index.js";
 
 describe("option.params", function () {
+  describe("sync API", function () {
+    for (const params of [0, false, ""]) {
+      it(`honors falsy params ${JSON.stringify(params)}`, function () {
+        const data = transformSync(
+          ["record"],
+          { params },
+          function (record, value) {
+            return [record, value];
+          },
+        );
+        data.should.eql([["record", params]]);
+      });
+    }
+
+    for (const params of [undefined, null]) {
+      it(`rejects callback handlers with params ${params}`, function () {
+        (function () {
+          transformSync(["record"], { params }, function (record, callback) {
+            callback(null, record);
+          });
+        }).should.throw(
+          "Invalid Handler: only synchronous handlers are supported",
+        );
+      });
+    }
+  });
+
   it("sync", function (next) {
     const generator = generate({ length: 100, objectMode: true, seed: 1 });
     const transformer = generator.pipe(