fix: issue with bound let always operating as controlled

src/__tests__/fixtures/let/__snapshots__/let-bound-controlled/node.render.expected.html

@@ -0,0 +1,6 @@
+<div>
+  1
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-controlled/web.render.expected.html

@@ -0,0 +1,6 @@
+<div>
+  1
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-controlled/web.step-0.expected.html

@@ -0,0 +1,6 @@
+<div>
+  1
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-controlled/web.step-1.expected.html

@@ -0,0 +1,6 @@
+<div>
+  2
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-controlled/web.step-2.expected.html

@@ -0,0 +1,6 @@
+<div>
+  2
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-uncontrolled/node.render.expected.html

@@ -0,0 +1,6 @@
+<div>
+  1
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-uncontrolled/web.render.expected.html

@@ -0,0 +1,6 @@
+<div>
+  1
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-uncontrolled/web.step-0.expected.html

@@ -0,0 +1,6 @@
+<div>
+  1
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-uncontrolled/web.step-1.expected.html

@@ -0,0 +1,6 @@
+<div>
+  2
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/__snapshots__/let-bound-uncontrolled/web.step-2.expected.html

@@ -0,0 +1,6 @@
+<div>
+  3
+</div>
+<button>
+  Increment
+</button>

src/__tests__/fixtures/let/index.test.ts

@@ -12,7 +12,7 @@ describe(
 );
 
 describe(
-  "<let> bound",
+  "<let> bound controlled",
   fixture("./templates/bound.marko", [
     { value: 1, valueChange() {} },
     increment,
@@ -21,6 +21,16 @@ describe(
   ])
 );
 
+describe(
+  "<let> bound uncontrolled",
+  fixture("./templates/bound.marko", [
+    { value: 1 },
+    { value: 2 },
+    increment,
+    increment,
+  ])
+);
+
 describe(
   "<let> read assignment",
   fixture("./templates/read-assignment.marko", [

src/transform/attribute-bindings.ts

@@ -13,16 +13,18 @@ const AttributeVisitor = {
     }
 
     const tempId = t.identifier("_");
-    attr.node.bound = false;
-    attr.insertAfter(
-      t.markoAttribute(
-        `${attr.node.name}Change`,
-        t.arrowFunctionExpression(
-          [tempId],
-          t.assignmentExpression("=", value.node, tempId)
-        )
+
+    const changeAttr = t.markoAttribute(
+      `${attr.node.name}Change`,
+      t.arrowFunctionExpression(
+        [tempId],
+        t.assignmentExpression("=", value.node, tempId)
       )
     );
+
+    attr.node.bound = false;
+    changeAttr.extra = { ___wasBound: true };
+    attr.insertAfter(changeAttr);
   },
 } as t.Visitor;
 

src/util/replace-assignments/transform.ts

@@ -30,12 +30,23 @@ export default function replaceAssignments(
     }
 
     if (value) {
-      assignment.replaceWith(
-        t.callExpression(importDefault(file, __dirname, "assign"), [
-          fnExpression,
-          value,
-        ])
-      );
+      const parent = assignment.parentPath!;
+      if (
+        // If the assignment was from a bound attribute
+        // we just replace the attr value with the change function.
+        parent.isFunction() &&
+        parent.parentPath!.isMarkoAttribute() &&
+        parent.parentPath!.node.extra?.___wasBound
+      ) {
+        parent.replaceWith(fnExpression);
+      } else {
+        assignment.replaceWith(
+          t.callExpression(importDefault(file, __dirname, "assign"), [
+            fnExpression,
+            value,
+          ])
+        );
+      }
     }
   }
 }