From cbe6460406257fea863470b16e9f70e3465ec72c Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Thu, 23 Jan 2025 13:55:32 -0700
Subject: [PATCH 1/8] fix: add dangling slot definition

---
 .../slot-forwarding/slots/dangling/expected.html         | 4 ++--
 .../slots/dangling/modules/x/leaf/leaf.html              | 2 +-
 .../slots/dangling/modules/x/slot/slot.html              | 4 ++--
 .../src/__tests__/utils/expected-failures.ts             | 4 ++--
 packages/@lwc/ssr-compiler/src/compile-template/index.ts | 1 +
 .../compile-template/transformers/component/component.ts | 3 +++
 .../transformers/component/lwc-component.ts              | 3 +++
 .../transformers/component/slotted-content.ts            | 3 ++-
 .../src/compile-template/transformers/element.ts         | 9 +++++++++
 .../src/compile-template/transformers/slot.ts            | 8 ++++++--
 10 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html
index aa23e8774b..b9dc6b9142 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html
@@ -2,12 +2,12 @@
   <x-slot>
     <x-leaf>
       <!---->
-      <h1 slot="bottom">
+      <h1 slot="leafBottom">
         bottom content
       </h1>
       <!---->
       <!---->
-      <h1>
+      <h1 slot="leafBottom">
         top content
       </h1>
       <!---->
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html
index 039365a7a7..a735614a68 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html
@@ -1,4 +1,4 @@
 <template lwc:render-mode="light">
-    <slot name="top" slot="bottom"></slot>
+    <slot name="top" slot="leafBottom"></slot>
     <slot name="bottom"></slot>
 </template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html
index e641874967..e13bdfa20b 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html
@@ -1,6 +1,6 @@
 <template lwc:render-mode="light">
     <x-leaf>
-        <slot name="top" slot="bottom"></slot>
-        <slot name="bottom" slot="top"></slot>
+        <slot name="top" slot="top"></slot>
+        <slot name="bottom" slot="bottom"></slot>
     </x-leaf>
 </template>
\ No newline at end of file
diff --git a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
index b2f8518054..f3ffe0e2df 100644
--- a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
+++ b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
@@ -13,8 +13,8 @@ export const expectedFailures = new Set([
     'exports/component-as-default/index.js',
     'known-boolean-attributes/default-def-html-attributes/static-on-component/index.js',
     'render-dynamic-value/index.js',
-    'slot-forwarding/slots/mixed/index.js',
-    'slot-forwarding/slots/dangling/index.js',
+    //'slot-forwarding/slots/mixed/index.js',
+    //'slot-forwarding/slots/dangling/index.js',
     'wire/errors/throws-on-computed-key/index.js',
     'wire/errors/throws-when-colliding-prop-then-method/index.js',
 ]);
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/index.ts b/packages/@lwc/ssr-compiler/src/compile-template/index.ts
index 037d51299f..a56627281e 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/index.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/index.ts
@@ -31,6 +31,7 @@ const bExportTemplate = esTemplate`
         // These should be scoped to the "tmpl" function however, to avoid conflicts with other templates.
         let textContentBuffer = '';
         let didBufferTextContent = false;
+        let danglingSlotName = null;
 
         // Establishes a contextual relationship between two components for ContextProviders.
         // This variable will typically get overridden (shadowed) within slotted content.
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts
index 305878fdd4..832c3fdd1a 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts
@@ -19,6 +19,9 @@ const bYieldFromChildGenerator = esTemplateWithYield`
     {
         const childProps = ${/* child props */ is.objectExpression};
         const childAttrs = ${/* child attrs */ is.objectExpression};
+        if (danglingSlotName) {
+            childAttrs.slot = danglingSlotName;
+        }
         ${
             /*
                 Slotted content is inserted here.
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts
index b7076424c9..88a1801e60 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts
@@ -25,6 +25,9 @@ const bYieldFromDynamicComponentConstructorGenerator = esTemplateWithYield`
         }
         const childProps = ${/* child props */ is.objectExpression};
         const childAttrs = ${/* child attrs */ is.objectExpression};
+        if (danglingSlotName) {
+            childAttrs.slot = danglingSlotName;
+        }
         ${
             /*
                 Slotted content is inserted here.
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts
index 6fa1660203..bf9a8ad357 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts
@@ -78,7 +78,8 @@ const bGenerateSlottedContent = esTemplateWithYield`
 const bAddSlottedContent = esTemplate`
     addSlottedContent(${/* slot name */ is.expression} ?? "", async function* generateSlottedContent(contextfulParent, ${
         /* scoped slot data variable */ isNullableOf(is.identifier)
-    }) {
+    }, danglingSlotName) {
+        debugger;
         // FIXME: make validation work again  
         ${/* slot content */ false}
     }, ${/* content map */ is.identifier});
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
index 66341e2355..3fd6d9438b 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
@@ -120,6 +120,14 @@ const bConditionallyYieldScopeTokenClass = esTemplateWithYield`
     }
 `<EsIfStatement>;
 
+const bConditionallyYieldDanglingSlotName = esTemplateWithYield`
+    {
+        if (danglingSlotName) {
+            yield \` slot="\${danglingSlotName}"\`; 
+        }   
+    }
+`<EsBlockStatement>;
+
 const bYieldSanitizedHtml = esTemplateWithYield`
     yield sanitizeHtmlContent(${/* lwc:inner-html content */ is.expression})
 `;
@@ -263,6 +271,7 @@ export const Element: Transformer<IrElement | IrExternalComponent | IrSlot> = fu
 
     return [
         bYield(b.literal(`<${node.name}`)),
+        ...[bConditionallyYieldDanglingSlotName()],
         // If we haven't already prefixed the scope token to an existing class, add an explicit class here
         ...(hasClassAttribute ? [] : [bConditionallyYieldScopeTokenClass()]),
         ...yieldAttrsAndProps,
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts
index 3dcdea4adc..d86d44a36b 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts
@@ -30,6 +30,8 @@ const bConditionalSlot = esTemplateWithYield`
         const scopedGenerators = scopedSlottedContent?.[slotName ?? ""];
         const mismatchedSlots = isScopedSlot ? lightGenerators : scopedGenerators;
         const generators = isScopedSlot ? scopedGenerators : lightGenerators;
+        debugger;
+        danglingSlotName = ${/* danglingSlotName */ is.expression} || danglingSlotName;
 
         // start bookend HTML comment for light DOM slot vfragment
         if (!isSlotted) {
@@ -43,7 +45,7 @@ const bConditionalSlot = esTemplateWithYield`
 
         if (generators) {
             for (let i = 0; i < generators.length; i++) {
-                yield* generators[i](contextfulParent, ${/* scoped slot data */ isNullableOf(is.expression)});
+                yield* generators[i](contextfulParent, ${/* scoped slot data */ isNullableOf(is.expression)}, danglingSlotName);
                 // Scoped slotted data is separated by bookends. Final bookends are added outside of the loop below.
                 if (isScopedSlot && i < generators.length - 1) {
                     yield '<!---->';
@@ -90,5 +92,7 @@ export const Slot: Transformer<IrSlot> = function Slot(node, ctx): EsStatement[]
     const slotChildren = irChildrenToEs(node.children, ctx);
     const isScopedSlot = b.literal(Boolean(slotBound));
     const isSlotted = b.literal(Boolean(ctx.isSlotted));
-    return [bConditionalSlot(isScopedSlot, isSlotted, slotName, slotBound, slotChildren, slotAst)];
+    const danglingSlotName = bAttributeValue(node, 'slot');
+    debugger;
+    return [bConditionalSlot(isScopedSlot, isSlotted, slotName, danglingSlotName, slotBound, slotChildren, slotAst)];
 };

From c1664868ff04f616c7a20ce5fbfd31528379e5cd Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Fri, 24 Jan 2025 11:03:50 -0700
Subject: [PATCH 2/8] fix: scoped slot case, nested cases

---
 .../slots/dangling/expected.html              | 10 ++++----
 .../modules/x/container/container.html        |  2 +-
 .../slots/dangling/modules/x/leaf/leaf.html   |  4 +--
 .../slots/dangling/modules/x/slot/slot.html   |  4 +--
 .../src/__tests__/utils/expected-failures.ts  |  2 --
 .../src/compile-template/index.ts             |  4 ++-
 .../transformers/component/component.ts       |  8 ++++--
 .../transformers/component/lwc-component.ts   |  8 ++++--
 .../transformers/component/slotted-content.ts |  3 +--
 .../compile-template/transformers/element.ts  |  8 ++++--
 .../src/compile-template/transformers/slot.ts | 25 ++++++++++++++-----
 11 files changed, 51 insertions(+), 27 deletions(-)

diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html
index b9dc6b9142..adfb2329a5 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/expected.html
@@ -2,14 +2,14 @@
   <x-slot>
     <x-leaf>
       <!---->
-      <h1 slot="leafBottom">
-        bottom content
+      <h1 slot="dangling">
+        top content
       </h1>
       <!---->
       <!---->
-      <h1 slot="leafBottom">
-        top content
-      </h1>
+      <h2>
+        bottom content
+      </h2>
       <!---->
     </x-leaf>
   </x-slot>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/container/container.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/container/container.html
index d6153f7e58..616c5495b8 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/container/container.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/container/container.html
@@ -1,6 +1,6 @@
 <template lwc:render-mode="light">
     <x-slot>
         <h1 slot="top">top content</h1>
-        <h1 slot="bottom">bottom content</h1>
+        <h2 slot="bottom">bottom content</h2>
     </x-slot>
 </template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html
index a735614a68..dc9ac68111 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/leaf/leaf.html
@@ -1,4 +1,4 @@
 <template lwc:render-mode="light">
-    <slot name="top" slot="leafBottom"></slot>
-    <slot name="bottom"></slot>
+    <slot name="leafTop" slot="dangling"></slot>
+    <slot name="leafBottom"></slot>
 </template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html
index e13bdfa20b..963a3fceca 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/modules/x/slot/slot.html
@@ -1,6 +1,6 @@
 <template lwc:render-mode="light">
     <x-leaf>
-        <slot name="top" slot="top"></slot>
-        <slot name="bottom" slot="bottom"></slot>
+        <slot name="top" slot="leafTop"></slot>
+        <slot name="bottom" slot="leafBottom"></slot>
     </x-leaf>
 </template>
\ No newline at end of file
diff --git a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
index f3ffe0e2df..4d02bf9f22 100644
--- a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
+++ b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
@@ -13,8 +13,6 @@ export const expectedFailures = new Set([
     'exports/component-as-default/index.js',
     'known-boolean-attributes/default-def-html-attributes/static-on-component/index.js',
     'render-dynamic-value/index.js',
-    //'slot-forwarding/slots/mixed/index.js',
-    //'slot-forwarding/slots/dangling/index.js',
     'wire/errors/throws-on-computed-key/index.js',
     'wire/errors/throws-when-colliding-prop-then-method/index.js',
 ]);
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/index.ts b/packages/@lwc/ssr-compiler/src/compile-template/index.ts
index a56627281e..041ef68f94 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/index.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/index.ts
@@ -31,7 +31,9 @@ const bExportTemplate = esTemplate`
         // These should be scoped to the "tmpl" function however, to avoid conflicts with other templates.
         let textContentBuffer = '';
         let didBufferTextContent = false;
-        let danglingSlotName = null;
+
+        // This will get overridden but requires initialization.
+        const slotAttributeValue = null;
 
         // Establishes a contextual relationship between two components for ContextProviders.
         // This variable will typically get overridden (shadowed) within slotted content.
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts
index 832c3fdd1a..adf94177dc 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/component.ts
@@ -19,8 +19,12 @@ const bYieldFromChildGenerator = esTemplateWithYield`
     {
         const childProps = ${/* child props */ is.objectExpression};
         const childAttrs = ${/* child attrs */ is.objectExpression};
-        if (danglingSlotName) {
-            childAttrs.slot = danglingSlotName;
+        /* 
+            If a slotAttributeValue is present, it is dangling and should be assigned to any slotted content. This behavior aligns with v1 and engine-dom.
+            See: engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/ for example case.
+        */
+        if (slotAttributeValue) {
+            childAttrs.slot = slotAttributeValue;
         }
         ${
             /*
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts
index 88a1801e60..8cfb10818a 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/lwc-component.ts
@@ -25,8 +25,12 @@ const bYieldFromDynamicComponentConstructorGenerator = esTemplateWithYield`
         }
         const childProps = ${/* child props */ is.objectExpression};
         const childAttrs = ${/* child attrs */ is.objectExpression};
-        if (danglingSlotName) {
-            childAttrs.slot = danglingSlotName;
+        /* 
+            If a slotAttributeValue is present, it is dangling and should be assigned to any slotted content. This behavior aligns with v1 and engine-dom.
+            See: engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/ for example case.
+        */
+        if (slotAttributeValue) {
+            childAttrs.slot = slotAttributeValue;
         }
         ${
             /*
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts
index bf9a8ad357..8ad46d5d5e 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/component/slotted-content.ts
@@ -78,8 +78,7 @@ const bGenerateSlottedContent = esTemplateWithYield`
 const bAddSlottedContent = esTemplate`
     addSlottedContent(${/* slot name */ is.expression} ?? "", async function* generateSlottedContent(contextfulParent, ${
         /* scoped slot data variable */ isNullableOf(is.identifier)
-    }, danglingSlotName) {
-        debugger;
+    }, slotAttributeValue) {
         // FIXME: make validation work again  
         ${/* slot content */ false}
     }, ${/* content map */ is.identifier});
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
index 3fd6d9438b..e2b86b94cb 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
@@ -120,10 +120,14 @@ const bConditionallyYieldScopeTokenClass = esTemplateWithYield`
     }
 `<EsIfStatement>;
 
+/* 
+    If a slotAttributeValue is present, it is dangling and should be assigned to any slotted content. This behavior aligns with v1 and engine-dom.
+    See: engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/ for example case.
+*/
 const bConditionallyYieldDanglingSlotName = esTemplateWithYield`
     {
-        if (danglingSlotName) {
-            yield \` slot="\${danglingSlotName}"\`; 
+        if (slotAttributeValue) {
+            yield \` slot="\${slotAttributeValue}"\`; 
         }   
     }
 `<EsBlockStatement>;
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts
index d86d44a36b..952619235d 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/slot.ts
@@ -30,9 +30,13 @@ const bConditionalSlot = esTemplateWithYield`
         const scopedGenerators = scopedSlottedContent?.[slotName ?? ""];
         const mismatchedSlots = isScopedSlot ? lightGenerators : scopedGenerators;
         const generators = isScopedSlot ? scopedGenerators : lightGenerators;
-        debugger;
-        danglingSlotName = ${/* danglingSlotName */ is.expression} || danglingSlotName;
-
+        /* 
+            If a slotAttributeValue is present, it should be provided for assignment to any slotted content. This behavior aligns with v1 and engine-dom.
+            See: engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/ for example.
+            Note the slot mapping does not work for scoped slots, so the slot name is not rendered in this case.
+            See: engine-server/src/__tests__/fixtures/slot-forwarding/scoped-slots for example.
+        */
+        const danglingSlotName = !isScopedSlot ? ${/* slotAttributeValue */ is.expression} || slotAttributeValue : null;
         // start bookend HTML comment for light DOM slot vfragment
         if (!isSlotted) {
             yield '<!---->';
@@ -92,7 +96,16 @@ export const Slot: Transformer<IrSlot> = function Slot(node, ctx): EsStatement[]
     const slotChildren = irChildrenToEs(node.children, ctx);
     const isScopedSlot = b.literal(Boolean(slotBound));
     const isSlotted = b.literal(Boolean(ctx.isSlotted));
-    const danglingSlotName = bAttributeValue(node, 'slot');
-    debugger;
-    return [bConditionalSlot(isScopedSlot, isSlotted, slotName, danglingSlotName, slotBound, slotChildren, slotAst)];
+    const slotAttributeValue = bAttributeValue(node, 'slot');
+    return [
+        bConditionalSlot(
+            isScopedSlot,
+            isSlotted,
+            slotName,
+            slotAttributeValue,
+            slotBound,
+            slotChildren,
+            slotAst
+        ),
+    ];
 };

From 7460711ed45c1d90941b902d66f469acab0c15fd Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Fri, 24 Jan 2025 11:45:00 -0700
Subject: [PATCH 3/8] fix: review comments

---
 .../src/compile-template/transformers/element.ts       | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
index e2b86b94cb..8a80407fa9 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/element.ts
@@ -125,11 +125,9 @@ const bConditionallyYieldScopeTokenClass = esTemplateWithYield`
     See: engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling/ for example case.
 */
 const bConditionallyYieldDanglingSlotName = esTemplateWithYield`
-    {
-        if (slotAttributeValue) {
-            yield \` slot="\${slotAttributeValue}"\`; 
-        }   
-    }
+    if (slotAttributeValue) {
+        yield \` slot="\${slotAttributeValue}"\`; 
+    }   
 `<EsBlockStatement>;
 
 const bYieldSanitizedHtml = esTemplateWithYield`
@@ -275,7 +273,7 @@ export const Element: Transformer<IrElement | IrExternalComponent | IrSlot> = fu
 
     return [
         bYield(b.literal(`<${node.name}`)),
-        ...[bConditionallyYieldDanglingSlotName()],
+        bConditionallyYieldDanglingSlotName(),
         // If we haven't already prefixed the scope token to an existing class, add an explicit class here
         ...(hasClassAttribute ? [] : [bConditionallyYieldScopeTokenClass()]),
         ...yieldAttrsAndProps,

From 721e06360b92f5ed0d96775438a0bd104bd35321 Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Fri, 24 Jan 2025 13:31:57 -0700
Subject: [PATCH 4/8] fix: additional test

---
 .../slots/dangling-component/error.txt           |  0
 .../slots/dangling-component/expected.html       | 16 ++++++++++++++++
 .../slots/dangling-component/index.js            |  4 ++++
 .../modules/x/component/component.html           |  3 +++
 .../modules/x/component/component.js             |  5 +++++
 .../modules/x/container/container.html           |  6 ++++++
 .../modules/x/container/container.js             |  5 +++++
 .../dangling-component/modules/x/leaf/leaf.html  |  4 ++++
 .../dangling-component/modules/x/leaf/leaf.js    |  5 +++++
 .../dangling-component/modules/x/slot/slot.html  |  6 ++++++
 .../dangling-component/modules/x/slot/slot.js    |  5 +++++
 11 files changed, 59 insertions(+)
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/error.txt
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/expected.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/index.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.js

diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/error.txt b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/error.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/expected.html
new file mode 100644
index 0000000000..63ea1759fe
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/expected.html
@@ -0,0 +1,16 @@
+<x-dangling-container>
+  <x-slot>
+    <x-leaf>
+      <!---->
+      <x-component slot="dangling">
+        Component content
+      </x-component>
+      <!---->
+      <!---->
+      <x-component>
+        Component content
+      </x-component>
+      <!---->
+    </x-leaf>
+  </x-slot>
+</x-dangling-container>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/index.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/index.js
new file mode 100644
index 0000000000..b202a15a0a
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/index.js
@@ -0,0 +1,4 @@
+export const tagName = 'x-dangling-container';
+export { default } from 'x/container';
+export * from 'x/container';
+export const features = [];
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.html
new file mode 100644
index 0000000000..17ad53e7e1
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.html
@@ -0,0 +1,3 @@
+<template lwc:render-mode="light">
+    Component content
+</template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/component/component.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.html
new file mode 100644
index 0000000000..685193646f
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.html
@@ -0,0 +1,6 @@
+<template lwc:render-mode="light">
+    <x-slot>
+        <x-component slot="top"></x-component>
+        <x-component slot="bottom"></x-component>
+    </x-slot>
+</template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/container/container.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.html
new file mode 100644
index 0000000000..dc9ac68111
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.html
@@ -0,0 +1,4 @@
+<template lwc:render-mode="light">
+    <slot name="leafTop" slot="dangling"></slot>
+    <slot name="leafBottom"></slot>
+</template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/leaf/leaf.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.html
new file mode 100644
index 0000000000..963a3fceca
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.html
@@ -0,0 +1,6 @@
+<template lwc:render-mode="light">
+    <x-leaf>
+        <slot name="top" slot="leafTop"></slot>
+        <slot name="bottom" slot="leafBottom"></slot>
+    </x-leaf>
+</template>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slot-forwarding/slots/dangling-component/modules/x/slot/slot.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}

From ddea5e4b3c1ed66b1ba90253bee43faf5db7c876 Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Mon, 27 Jan 2025 13:02:35 -0700
Subject: [PATCH 5/8] fix: default slotted content

---
 .../implicit-no-template/light/error.txt      |  0
 .../implicit-no-template/light/expected.html  |  4 +++
 .../implicit-no-template/light/index.js       |  3 ++
 .../light/modules/x/inner/inner.js            |  5 ++++
 .../light/modules/x/outer/outer.html          |  6 ++++
 .../light/modules/x/outer/outer.js            |  5 ++++
 .../implicit-no-template/shadow/error.txt     |  0
 .../implicit-no-template/shadow/expected.html | 10 +++++++
 .../implicit-no-template/shadow/index.js      |  3 ++
 .../shadow/modules/x/inner/inner.js           |  3 ++
 .../shadow/modules/x/outer/outer.html         |  6 ++++
 .../shadow/modules/x/outer/outer.js           |  5 ++++
 packages/@lwc/ssr-runtime/src/render.ts       | 29 ++++++++++++++-----
 13 files changed, 71 insertions(+), 8 deletions(-)
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/error.txt
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/expected.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/index.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/inner/inner.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/error.txt
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/index.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/inner/inner.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js

diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/error.txt b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/error.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/expected.html
new file mode 100644
index 0000000000..ada6887b85
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/expected.html
@@ -0,0 +1,4 @@
+<x-outer>
+  <x-inner>
+  </x-inner>
+</x-outer>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/index.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/index.js
new file mode 100644
index 0000000000..17a015b5ea
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/index.js
@@ -0,0 +1,3 @@
+export const tagName = 'x-outer';
+export { default } from 'x/outer';
+export * from 'x/outer';
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/inner/inner.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/inner/inner.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/inner/inner.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.html
new file mode 100644
index 0000000000..e6479b1b01
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.html
@@ -0,0 +1,6 @@
+<template lwc:render-mode="light">
+    <x-inner>
+        I am default slot
+        <div slot="foo">I am the foo slot</div>
+    </x-inner>
+</template>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/light/modules/x/outer/outer.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/error.txt b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/error.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html
new file mode 100644
index 0000000000..2ed009a4ec
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html
@@ -0,0 +1,10 @@
+<x-outer>
+  <x-inner>
+    <template shadowrootmode="open">
+    </template>
+    slotted content
+    <h2 slot="bob">
+      more content
+    </h2>
+  </x-inner>
+</x-outer>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/index.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/index.js
new file mode 100644
index 0000000000..17a015b5ea
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/index.js
@@ -0,0 +1,3 @@
+export const tagName = 'x-outer';
+export { default } from 'x/outer';
+export * from 'x/outer';
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/inner/inner.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/inner/inner.js
new file mode 100644
index 0000000000..ca8dce94e0
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/inner/inner.js
@@ -0,0 +1,3 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html
new file mode 100644
index 0000000000..2542b79fe0
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html
@@ -0,0 +1,6 @@
+<template>
+    <x-inner>
+        slotted content
+        <h2 slot="bob">more content</h2>
+    </x-inner>
+</template>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js
new file mode 100644
index 0000000000..0679d2bc10
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    static renderMode = 'light';
+}
diff --git a/packages/@lwc/ssr-runtime/src/render.ts b/packages/@lwc/ssr-runtime/src/render.ts
index 188c169ba7..b6c240686d 100644
--- a/packages/@lwc/ssr-runtime/src/render.ts
+++ b/packages/@lwc/ssr-runtime/src/render.ts
@@ -101,27 +101,40 @@ export function renderAttrsNoYield(
 }
 
 export function* fallbackTmpl(
-    _shadowSlottedContent: unknown,
-    _lightSlottedContent: unknown,
-    _scopedSlottedContent: unknown,
+    _shadowSlottedContent: any,
+    _lightSlottedContent: any,
+    _scopedSlottedContent: any,
     Cmp: LightningElementConstructor,
     _instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
-        yield '<template shadowrootmode="open"></template>';
+        yield `<template shadowrootmode="open"></template>`;
+        renderSlottedContent(_lightSlottedContent, _instance);
     }
 }
 
 export function fallbackTmplNoYield(
     emit: (segment: string) => void,
-    _shadowSlottedContent: unknown,
-    _lightSlottedContent: unknown,
-    _scopedSlottedContent: unknown,
+    _shadowSlottedContent: any,
+    _lightSlottedContent: any,
+    _scopedSlottedContent: any,
     Cmp: LightningElementConstructor,
     _instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
-        emit('<template shadowrootmode="open"></template>');
+        emit(`<template shadowrootmode="open"></template>`);
+        renderSlottedContent(_lightSlottedContent, emit);
+    }
+}
+
+function renderSlottedContent(_lightSlottedContent: any, contextfulParent: any) {
+    if (_lightSlottedContent) {
+        for (const slotName in _lightSlottedContent) {
+            const generators = _lightSlottedContent[slotName];
+            for (let i = 0; i < generators.length; i++) {
+                generators[i](contextfulParent, null, slotName);
+            }
+        }
     }
 }
 

From 7e2a5de521c1aeeb2da7b122d27f62774ddfa579 Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Wed, 29 Jan 2025 10:07:15 -0700
Subject: [PATCH 6/8] fix: render shadow slotted content for no template case

---
 .../implicit-no-template/shadow/expected.html  | 18 ++++++++++--------
 .../shadow/modules/x/outer/outer.html          |  4 ++--
 .../shadow/modules/x/outer/outer.js            |  4 +---
 packages/@lwc/ssr-runtime/src/render.ts        | 17 +++++------------
 4 files changed, 18 insertions(+), 25 deletions(-)

diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html
index 2ed009a4ec..bc3c9ecc25 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/expected.html
@@ -1,10 +1,12 @@
 <x-outer>
-  <x-inner>
-    <template shadowrootmode="open">
-    </template>
-    slotted content
-    <h2 slot="bob">
-      more content
-    </h2>
-  </x-inner>
+  <template shadowrootmode="open">
+    <x-inner>
+      <template shadowrootmode="open">
+      </template>
+      I am default slot
+      <div slot="foo">
+        I am the foo slot
+      </div>
+    </x-inner>
+  </template>
 </x-outer>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html
index 2542b79fe0..03c77e467f 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.html
@@ -1,6 +1,6 @@
 <template>
     <x-inner>
-        slotted content
-        <h2 slot="bob">more content</h2>
+        I am default slot
+        <div slot="foo">I am the foo slot</div>
     </x-inner>
 </template>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js
index 0679d2bc10..ca8dce94e0 100644
--- a/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/slots-basic/implicit-no-template/shadow/modules/x/outer/outer.js
@@ -1,5 +1,3 @@
 import { LightningElement } from 'lwc';
 
-export default class extends LightningElement {
-    static renderMode = 'light';
-}
+export default class extends LightningElement {}
diff --git a/packages/@lwc/ssr-runtime/src/render.ts b/packages/@lwc/ssr-runtime/src/render.ts
index b6c240686d..32213b0c8a 100644
--- a/packages/@lwc/ssr-runtime/src/render.ts
+++ b/packages/@lwc/ssr-runtime/src/render.ts
@@ -109,7 +109,9 @@ export function* fallbackTmpl(
 ) {
     if (Cmp.renderMode !== 'light') {
         yield `<template shadowrootmode="open"></template>`;
-        renderSlottedContent(_lightSlottedContent, _instance);
+        if (_shadowSlottedContent) {
+            yield _shadowSlottedContent(_instance);
+        }
     }
 }
 
@@ -123,17 +125,8 @@ export function fallbackTmplNoYield(
 ) {
     if (Cmp.renderMode !== 'light') {
         emit(`<template shadowrootmode="open"></template>`);
-        renderSlottedContent(_lightSlottedContent, emit);
-    }
-}
-
-function renderSlottedContent(_lightSlottedContent: any, contextfulParent: any) {
-    if (_lightSlottedContent) {
-        for (const slotName in _lightSlottedContent) {
-            const generators = _lightSlottedContent[slotName];
-            for (let i = 0; i < generators.length; i++) {
-                generators[i](contextfulParent, null, slotName);
-            }
+        if (_shadowSlottedContent) {
+            _shadowSlottedContent(emit, _instance);
         }
     }
 }

From ecedbcf4185a9bca8e29d10a7c2b0e1d8f2ce907 Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Wed, 29 Jan 2025 11:46:18 -0700
Subject: [PATCH 7/8] fix: update types

---
 packages/@lwc/ssr-runtime/src/render.ts | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/packages/@lwc/ssr-runtime/src/render.ts b/packages/@lwc/ssr-runtime/src/render.ts
index 32213b0c8a..e1f2d0e10b 100644
--- a/packages/@lwc/ssr-runtime/src/render.ts
+++ b/packages/@lwc/ssr-runtime/src/render.ts
@@ -101,32 +101,32 @@ export function renderAttrsNoYield(
 }
 
 export function* fallbackTmpl(
-    _shadowSlottedContent: any,
-    _lightSlottedContent: any,
-    _scopedSlottedContent: any,
+    shadowSlottedContent: AsyncGeneratorFunction,
+    _lightSlottedContent: unknown,
+    _scopedSlottedContent: unknown,
     Cmp: LightningElementConstructor,
     _instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
         yield `<template shadowrootmode="open"></template>`;
-        if (_shadowSlottedContent) {
-            yield _shadowSlottedContent(_instance);
+        if (shadowSlottedContent) {
+            yield shadowSlottedContent(_instance);
         }
     }
 }
 
 export function fallbackTmplNoYield(
     emit: (segment: string) => void,
-    _shadowSlottedContent: any,
-    _lightSlottedContent: any,
-    _scopedSlottedContent: any,
+    shadowSlottedContent: AsyncGeneratorFunction,
+    _lightSlottedContent: unknown,
+    _scopedSlottedContent: unknown,
     Cmp: LightningElementConstructor,
     _instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
         emit(`<template shadowrootmode="open"></template>`);
-        if (_shadowSlottedContent) {
-            _shadowSlottedContent(emit, _instance);
+        if (shadowSlottedContent) {
+            shadowSlottedContent(emit, _instance);
         }
     }
 }

From d6941e320153bb7b657182b4913836cd39be1c26 Mon Sep 17 00:00:00 2001
From: John Hefferman <jhefferman@salesforce.com>
Date: Thu, 30 Jan 2025 11:06:49 -0700
Subject: [PATCH 8/8] fix: instance naming

---
 packages/@lwc/ssr-runtime/src/render.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/@lwc/ssr-runtime/src/render.ts b/packages/@lwc/ssr-runtime/src/render.ts
index e1f2d0e10b..4a635df8e2 100644
--- a/packages/@lwc/ssr-runtime/src/render.ts
+++ b/packages/@lwc/ssr-runtime/src/render.ts
@@ -105,12 +105,12 @@ export function* fallbackTmpl(
     _lightSlottedContent: unknown,
     _scopedSlottedContent: unknown,
     Cmp: LightningElementConstructor,
-    _instance: unknown
+    instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
         yield `<template shadowrootmode="open"></template>`;
         if (shadowSlottedContent) {
-            yield shadowSlottedContent(_instance);
+            yield shadowSlottedContent(instance);
         }
     }
 }
@@ -121,12 +121,12 @@ export function fallbackTmplNoYield(
     _lightSlottedContent: unknown,
     _scopedSlottedContent: unknown,
     Cmp: LightningElementConstructor,
-    _instance: unknown
+    instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
         emit(`<template shadowrootmode="open"></template>`);
         if (shadowSlottedContent) {
-            shadowSlottedContent(emit, _instance);
+            shadowSlottedContent(emit, instance);
         }
     }
 }