diff --git a/packages/@lwc/aria-reflection/package.json b/packages/@lwc/aria-reflection/package.json
index f9e0439f25..cf523560e9 100644
--- a/packages/@lwc/aria-reflection/package.json
+++ b/packages/@lwc/aria-reflection/package.json
@@ -34,8 +34,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/babel-plugin-component/package.json b/packages/@lwc/babel-plugin-component/package.json
index 5b75e64d65..2f3e2e0678 100644
--- a/packages/@lwc/babel-plugin-component/package.json
+++ b/packages/@lwc/babel-plugin-component/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/compiler/package.json b/packages/@lwc/compiler/package.json
index b38cd27656..a292a3dbcd 100755
--- a/packages/@lwc/compiler/package.json
+++ b/packages/@lwc/compiler/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/engine-core/package.json b/packages/@lwc/engine-core/package.json
index 2b410e8199..f65e1fe935 100644
--- a/packages/@lwc/engine-core/package.json
+++ b/packages/@lwc/engine-core/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/engine-dom/package.json b/packages/@lwc/engine-dom/package.json
index 2fc25226f7..d33cc5b75e 100644
--- a/packages/@lwc/engine-dom/package.json
+++ b/packages/@lwc/engine-dom/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/engine-server/package.json b/packages/@lwc/engine-server/package.json
index 5828dacf45..f0c0b2d913 100644
--- a/packages/@lwc/engine-server/package.json
+++ b/packages/@lwc/engine-server/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/errors/package.json b/packages/@lwc/errors/package.json
index 0a1cb520be..9b4ab36e3e 100644
--- a/packages/@lwc/errors/package.json
+++ b/packages/@lwc/errors/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/features/package.json b/packages/@lwc/features/package.json
index c0321aa808..ce4eea5824 100644
--- a/packages/@lwc/features/package.json
+++ b/packages/@lwc/features/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/module-resolver/package.json b/packages/@lwc/module-resolver/package.json
index 00f5e13fd4..80d9bd5839 100644
--- a/packages/@lwc/module-resolver/package.json
+++ b/packages/@lwc/module-resolver/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/rollup-plugin/README.md b/packages/@lwc/rollup-plugin/README.md
index 9c4fa03901..2780773ff0 100644
--- a/packages/@lwc/rollup-plugin/README.md
+++ b/packages/@lwc/rollup-plugin/README.md
@@ -37,3 +37,4 @@ export default {
 -   `disableSyntheticShadowSupport` (type: `boolean`, default: `false`) - Set to true if synthetic shadow DOM support is not needed, which can result in smaller output.
 -   `apiVersion` (type: `number`, default: `undefined`) - Set to a valid API version such as 58, 59, etc. This will be overriden if the component itself overrides the version with a `*.js-meta.xml` file.
 -   `enableStaticContentOptimization` (type: `boolean`, optional) - True if the static content optimization should be enabled. Passed to `@lwc/template-compiler`. True by default.
+-   `targetSSR` (type: `boolean`) - Utilize the experimental SSR compilation mode. False by default. Do not use unless you know what you're doing.
diff --git a/packages/@lwc/rollup-plugin/package.json b/packages/@lwc/rollup-plugin/package.json
index c0b29d9626..90a1aa7fb8 100644
--- a/packages/@lwc/rollup-plugin/package.json
+++ b/packages/@lwc/rollup-plugin/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/shared/package.json b/packages/@lwc/shared/package.json
index 8e88271f71..6247689d93 100644
--- a/packages/@lwc/shared/package.json
+++ b/packages/@lwc/shared/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/shared/src/ecmascript.ts b/packages/@lwc/shared/src/ecmascript.ts
new file mode 100644
index 0000000000..1735e79767
--- /dev/null
+++ b/packages/@lwc/shared/src/ecmascript.ts
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2024, salesforce.com, inc.
+ * All rights reserved.
+ * SPDX-License-Identifier: MIT
+ * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
+ */
+export const reservedKeywords = new Set([
+    'NaN',
+    'arguments',
+    'break',
+    'case',
+    'catch',
+    'class',
+    'const',
+    'continue',
+    'debugger',
+    'default',
+    'delete',
+    'do',
+    'else',
+    'enum',
+    'eval',
+    'export',
+    'extends',
+    'false',
+    'finally',
+    'for',
+    'function',
+    'if',
+    'implements',
+    'import',
+    'in',
+    'instanceof',
+    'interface',
+    'let',
+    'new',
+    'null',
+    'package',
+    'private',
+    'protected',
+    'public',
+    'return',
+    'static',
+    'super',
+    'switch',
+    'this',
+    'throw',
+    'true',
+    'try',
+    'typeof',
+    'undefined',
+    'var',
+    'void',
+    'while',
+    'with',
+    'yield',
+]);
diff --git a/packages/@lwc/shared/src/index.ts b/packages/@lwc/shared/src/index.ts
index 091638e8c2..f86a74fedc 100644
--- a/packages/@lwc/shared/src/index.ts
+++ b/packages/@lwc/shared/src/index.ts
@@ -8,6 +8,7 @@ import * as assert from './assert';
 
 export * from './api-version';
 export * from './aria';
+export * from './ecmascript';
 export * from './language';
 export * from './keys';
 export * from './void-elements';
diff --git a/packages/@lwc/ssr-compiler/package.json b/packages/@lwc/ssr-compiler/package.json
index 2fbbb084d0..e901d05559 100644
--- a/packages/@lwc/ssr-compiler/package.json
+++ b/packages/@lwc/ssr-compiler/package.json
@@ -7,7 +7,9 @@
     "version": "6.5.3",
     "description": "Compile component for use during server-side rendering",
     "keywords": [
-        "lwc"
+        "compiler",
+        "lwc",
+        "ssr"
     ],
     "homepage": "https://lwc.dev",
     "repository": {
@@ -30,8 +32,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test-manual": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
@@ -47,7 +48,7 @@
         "@lwc/sfdc-compiler-utils": "6.5.3-0",
         "@lwc/style-compiler": "6.5.3",
         "@lwc/template-compiler": "6.5.3",
-        "acorn": "~8.10.0",
+        "acorn": "8.10.0",
         "astring": "^1.8.6",
         "estree-toolkit": "^1.7.3",
         "immer": "^10.0.3",
diff --git a/packages/@lwc/ssr-compiler/src/__tests__/estemplate.spec.ts b/packages/@lwc/ssr-compiler/src/__tests__/estemplate.spec.ts
new file mode 100644
index 0000000000..968b75bdba
--- /dev/null
+++ b/packages/@lwc/ssr-compiler/src/__tests__/estemplate.spec.ts
@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 2024, salesforce.com, inc.
+ * All rights reserved.
+ * SPDX-License-Identifier: MIT
+ * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
+ */
+
+import { is, builders as b } from 'estree-toolkit';
+import { esTemplate, esTemplateWithYield } from '../estemplate';
+
+Object.entries({
+    esTemplate,
+    esTemplateWithYield,
+}).forEach(([topLevelFnName, topLevelFn]) => {
+    const yieldStmtsAllowed = topLevelFnName === 'esTemplateWithYield';
+
+    describe(topLevelFnName, () => {
+        describe('failure upon parse', () => {
+            yieldStmtsAllowed ||
+                test('with yield statements', () => {
+                    const createTemplate = () => topLevelFn`
+                    const foo = "bar";
+                    yield foo;
+                `;
+                    expect(createTemplate).toThrow('Unexpected token');
+                });
+
+            test('when attempting to replace unreplaceable code constructs', () => {
+                // Someone might try to create a template where 'class' or 'function'
+                // is provided as an argument to the ES template.
+                const isFunctionOrClass = (node: any) =>
+                    is.functionDeclaration(node) || is.classDeclaration(node);
+                const createTemplate = () => topLevelFn`
+                    ${isFunctionOrClass} classOrFunctionDecl {}
+                `;
+                expect(createTemplate).toThrow('Unexpected token');
+            });
+
+            test('syntax errors due to typo', () => {
+                const createTemplate = () => topLevelFn`
+                    calss MyCmp extends LightningElement {
+                        connectedCallbac() {
+                            console.log('if you see this, calss has been added to the JS language');
+                        }
+                    }
+                `;
+                expect(createTemplate).toThrow('Unexpected token');
+            });
+        });
+
+        describe('failure upon invocation', () => {
+            test('when replacing incorrect node type', () => {
+                const tmpl = topLevelFn`
+                    const ${is.identifier} = 'foo';
+                `;
+                const doReplacement = () => tmpl(b.literal('I am not an identifier'));
+                expect(doReplacement).toThrow(
+                    'Validation failed for templated node of type Identifier'
+                );
+            });
+        });
+
+        describe('successful replacement', () => {
+            yieldStmtsAllowed &&
+                test('with yield statements', () => {
+                    const tmpl = topLevelFn`
+                    yield ${is.literal};
+                `;
+                    const replacedAst = tmpl(b.literal('foo'));
+
+                    expect(replacedAst).toMatchObject({
+                        expression: {
+                            argument: {
+                                type: 'Literal',
+                                value: 'foo',
+                            },
+                            delegate: false,
+                            type: 'YieldExpression',
+                        },
+                        type: 'ExpressionStatement',
+                    });
+                });
+
+            test('with LH identifier nodes', () => {
+                const tmpl = topLevelFn`
+                    const ${is.identifier} = 'foobar'
+                `;
+                const replacedAst = tmpl(b.identifier('heyImNewHere'));
+                expect(replacedAst).toMatchObject({
+                    declarations: [
+                        {
+                            id: {
+                                name: 'heyImNewHere',
+                                type: 'Identifier',
+                            },
+                            init: {
+                                type: 'Literal',
+                                value: 'foobar',
+                            },
+                            type: 'VariableDeclarator',
+                        },
+                    ],
+                    kind: 'const',
+                    type: 'VariableDeclaration',
+                });
+            });
+            test('with multiple nodes', () => {
+                const tmpl = topLevelFn`
+                    const foo = ${is.literal} + ${is.identifier};
+                    fnCall(foo, ${is.objectExpression});
+                `;
+                const replacedAst = tmpl(
+                    b.literal(5),
+                    b.identifier('bar'),
+                    b.objectExpression([
+                        b.property('init', b.literal('config'), b.literal('someConfig')),
+                    ])
+                );
+
+                expect(replacedAst).toMatchObject([
+                    {
+                        declarations: [
+                            {
+                                id: {
+                                    name: 'foo',
+                                    type: 'Identifier',
+                                },
+                                init: {
+                                    left: {
+                                        type: 'Literal',
+                                        value: 5,
+                                    },
+                                    operator: '+',
+                                    right: {
+                                        name: 'bar',
+                                        type: 'Identifier',
+                                    },
+                                    type: 'BinaryExpression',
+                                },
+                                type: 'VariableDeclarator',
+                            },
+                        ],
+                        kind: 'const',
+                        type: 'VariableDeclaration',
+                    },
+                    {
+                        expression: {
+                            arguments: [
+                                {
+                                    name: 'foo',
+                                    type: 'Identifier',
+                                },
+                                {
+                                    properties: [
+                                        {
+                                            computed: false,
+                                            key: {
+                                                type: 'Literal',
+                                                value: 'config',
+                                            },
+                                            kind: 'init',
+                                            shorthand: false,
+                                            type: 'Property',
+                                            value: {
+                                                type: 'Literal',
+                                                value: 'someConfig',
+                                            },
+                                        },
+                                    ],
+                                    type: 'ObjectExpression',
+                                },
+                            ],
+                            callee: {
+                                name: 'fnCall',
+                                type: 'Identifier',
+                            },
+                            optional: false,
+                            type: 'CallExpression',
+                        },
+                        type: 'ExpressionStatement',
+                    },
+                ]);
+            });
+        });
+    });
+});
diff --git a/packages/@lwc/ssr-compiler/src/__tests__/fixtures.spec.ts b/packages/@lwc/ssr-compiler/src/__tests__/fixtures.spec.ts
index 432e716b43..4e18d3e6fa 100644
--- a/packages/@lwc/ssr-compiler/src/__tests__/fixtures.spec.ts
+++ b/packages/@lwc/ssr-compiler/src/__tests__/fixtures.spec.ts
@@ -9,18 +9,18 @@ import fs from 'fs';
 import path from 'path';
 
 import { rollup, RollupLog } from 'rollup';
-// @ts-ignore
 import lwcRollupPlugin from '@lwc/rollup-plugin';
 import { isVoidElement, HTML_NAMESPACE } from '@lwc/shared';
+import { FeatureFlagName } from '@lwc/features/dist/types';
 import { testFixtureDir } from '@lwc/jest-utils-lwc-internals';
-import { serverSideRenderComponent } from '../index';
+import { serverSideRenderComponent } from '@lwc/ssr-runtime';
 
 interface FixtureModule {
     tagName: string;
     default: any;
     generateMarkup: any;
     props?: { [key: string]: any };
-    features?: any[];
+    features?: FeatureFlagName[];
 }
 
 jest.setTimeout(10_000 /* 10 seconds */);
@@ -82,13 +82,19 @@ function formatHTML(src: string): string {
         if (src.charAt(pos) === '<') {
             const tagNameMatch = src.slice(pos).match(/(\w+)/);
 
+            if (!tagNameMatch) {
+                throw new Error(
+                    `Expected to find tagname at pos ${pos} but found "${src.slice(pos, 20)}"`
+                );
+            }
+
             // Special handling for `<style>` tags – these are not encoded, so we may hit '<' or '>'
             // inside the text content. So we just serialize it as-is.
-            if (tagNameMatch![0] === 'style') {
+            if (tagNameMatch[0] === 'style') {
                 const styleMatch = src.slice(pos).match(/<style([\s\S]*?)>([\s\S]*?)<\/style>/);
                 if (styleMatch) {
                     // opening tag
-                    const [wholeMatch, attrs, textContent] = styleMatch!;
+                    const [wholeMatch, attrs, textContent] = styleMatch;
                     res += getPadding() + `<style${attrs}>` + '\n';
                     depth++;
                     res += getPadding() + textContent + '\n';
@@ -99,12 +105,9 @@ function formatHTML(src: string): string {
                 }
             }
 
-            const isVoid = isVoidElement(tagNameMatch![0], HTML_NAMESPACE);
+            const isVoid = isVoidElement(tagNameMatch[0], HTML_NAMESPACE);
             const isClosing = src.charAt(pos + 1) === '/';
-            const isComment =
-                src.charAt(pos + 1) === '!' &&
-                src.charAt(pos + 2) === '-' &&
-                src.charAt(pos + 3) === '-';
+            const isComment = src.slice(pos, pos + 3) === '!--';
 
             start = pos;
             while (src.charAt(pos++) !== '>') {
diff --git a/packages/@lwc/ssr-compiler/src/compile-js/catalog-tmpls.ts b/packages/@lwc/ssr-compiler/src/compile-js/catalog-tmpls.ts
index fd88feed3a..04cd3e0b55 100644
--- a/packages/@lwc/ssr-compiler/src/compile-js/catalog-tmpls.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-js/catalog-tmpls.ts
@@ -9,18 +9,27 @@ import type { NodePath } from 'estree-toolkit';
 import type { ImportDeclaration } from 'estree';
 import type { ComponentMetaState } from './types';
 
+/**
+ * While traversing the component JS, this takes note of any .html files that are
+ * explicitly imported..
+ */
 export function catalogTmplImport(path: NodePath<ImportDeclaration>, state: ComponentMetaState) {
-    const specifier = path.node!.specifiers[0];
+    if (!path.node) {
+        return;
+    }
+
+    const { specifiers, source } = path.node;
+    const specifier = specifiers[0];
 
     if (
-        typeof path.node!.source.value !== 'string' ||
-        !path.node!.source.value!.endsWith('.html') ||
-        path.node!.specifiers.length !== 1 ||
+        typeof source.value !== 'string' ||
+        !source.value.endsWith('.html') ||
+        specifiers.length !== 1 ||
         specifier.type !== 'ImportDefaultSpecifier'
     ) {
         return;
     }
 
     state.tmplExplicitImports = state.tmplExplicitImports ?? new Map();
-    state.tmplExplicitImports.set(specifier.local.name, path.node!.source.value);
+    state.tmplExplicitImports.set(specifier.local.name, source.value);
 }
diff --git a/packages/@lwc/ssr-compiler/src/compile-js/generate-markup.ts b/packages/@lwc/ssr-compiler/src/compile-js/generate-markup.ts
index a689cbb493..1816a62188 100644
--- a/packages/@lwc/ssr-compiler/src/compile-js/generate-markup.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-js/generate-markup.ts
@@ -20,12 +20,10 @@ import type {
 } from 'estree';
 import type { ComponentMetaState } from './types';
 
-const isNullableExpressionStatement = isNullableOf(is.expressionStatement);
-
 const bGenerateMarkup = esTemplate<ExportNamedDeclaration>`
     export async function* generateMarkup(tagName, props, attrs, slotted) {
         attrs = attrs ?? {};
-        ${isNullableExpressionStatement};
+        ${isNullableOf(is.expressionStatement)};
         const instance = new ${is.identifier}({
             tagName: tagName.toUpperCase(),
         });
@@ -75,12 +73,15 @@ function bReflectedAttrsObj(reflectedPropNames: (keyof typeof AriaPropNameToAttr
         )
     );
 
-    // attrs = {
-    //   ...attrs,
-    //   get ['aria-checked']() {
-    //     return props.ariaChecked;
+    // This mutates the `attrs` object, adding the reflected aria attributes that have been
+    // detected. Example:
+    //
+    //   attrs = {
+    //     ...attrs,
+    //     get ['aria-checked']() {
+    //       return props.ariaChecked;
+    //     }
     //   }
-    // }
     return b.expressionStatement(
         b.assignmentExpression(
             '=',
@@ -90,6 +91,18 @@ function bReflectedAttrsObj(reflectedPropNames: (keyof typeof AriaPropNameToAttr
     );
 }
 
+/**
+ * This builds a generator function `generateMarkup` and adds it to the component JS's
+ * compilation output. `generateMarkup` acts as the glue between component JS and its
+ * template(s), including:
+ *
+ *  - managing reflection of attrs & props
+ *  - instantiating the component instance
+ *  - setting the internal state of that component instance
+ *  - invoking component lifecycle methods
+ *  - yielding the tag name & attributes
+ *  - deferring to the template function for yielding child content
+ */
 export function addGenerateMarkupExport(
     program: Program,
     state: ComponentMetaState,
diff --git a/packages/@lwc/ssr-compiler/src/compile-js/index.ts b/packages/@lwc/ssr-compiler/src/compile-js/index.ts
index 11ffddcd67..516542602a 100644
--- a/packages/@lwc/ssr-compiler/src/compile-js/index.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-js/index.ts
@@ -35,19 +35,22 @@ const visitors: Visitors = {
         catalogTmplImport(path, state);
         catalogStyleImport(path, state);
     },
-    ExportDefaultDeclaration(_path, _state) {},
     ClassDeclaration(path, state) {
+        if (!path.node?.superClass) {
+            return;
+        }
+
         if (
-            path.node?.superClass?.type === 'Identifier' &&
+            path.node.superClass.type === 'Identifier' &&
             // It is possible to inherit from something that inherits from
             // LightningElement, so the detection here needs additional work.
-            path.node?.superClass?.name === 'LightningElement'
+            path.node.superClass.name === 'LightningElement'
         ) {
             state.isLWC = true;
-            if (path.node!.id) {
-                state.lwcClassName = path.node!.id.name;
+            if (path.node.id) {
+                state.lwcClassName = path.node.id.name;
             } else {
-                path.node!.id = b.identifier('DefaultComponentName');
+                path.node.id = b.identifier('DefaultComponentName');
                 state.lwcClassName = 'DefaultComponentName';
             }
         }
@@ -128,7 +131,6 @@ export default function compileJS(src: string, filename: string) {
         tmplExplicitImports: null,
         cssExplicitImports: null,
         staticStylesheetIds: null,
-        props: [],
         reflectedPropsInPlay: new Set(),
     };
 
diff --git a/packages/@lwc/ssr-compiler/src/compile-js/lwc-import.ts b/packages/@lwc/ssr-compiler/src/compile-js/lwc-import.ts
index cb2c92818a..5306559ff2 100644
--- a/packages/@lwc/ssr-compiler/src/compile-js/lwc-import.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-js/lwc-import.ts
@@ -11,13 +11,18 @@ import type { ImportDeclaration } from 'estree';
 import type { NodePath } from 'estree-toolkit';
 import type { ComponentMetaState } from './types';
 
+/**
+ * This accomplishes two things:
+ *
+ *  1. it replaces "lwc" with "@lwc/ssr-runtime" in an import specifier
+ *  2. it makes note of the local var name associated with the `LightningElement` import
+ */
 export function replaceLwcImport(path: NodePath<ImportDeclaration>, state: ComponentMetaState) {
-    if (path.node!.source.value !== 'lwc') {
+    if (!path.node || path.node.source.value !== 'lwc') {
         return;
     }
 
-    const node = path.node!;
-    for (const specifier of node.specifiers) {
+    for (const specifier of path.node.specifiers) {
         if (
             specifier.type === 'ImportSpecifier' &&
             specifier.imported.type === 'Identifier' &&
@@ -28,5 +33,5 @@ export function replaceLwcImport(path: NodePath<ImportDeclaration>, state: Compo
         }
     }
 
-    path.replaceWith(b.importDeclaration(node.specifiers, b.literal('@lwc/ssr-runtime')));
+    path.replaceWith(b.importDeclaration(path.node.specifiers, b.literal('@lwc/ssr-runtime')));
 }
diff --git a/packages/@lwc/ssr-compiler/src/compile-js/stylesheets.ts b/packages/@lwc/ssr-compiler/src/compile-js/stylesheets.ts
index f7649ea88d..823a2f92c1 100644
--- a/packages/@lwc/ssr-compiler/src/compile-js/stylesheets.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-js/stylesheets.ts
@@ -32,8 +32,11 @@ export function catalogStyleImport(path: NodePath<ImportDeclaration>, state: Com
     state.cssExplicitImports.set(specifier.local.name, path.node!.source.value);
 }
 
-const componentNamePattern = /\/(?<componentName>[a-z_-]+)\/\k<componentName>\.[tj]s$/;
+const componentNamePattern = /[/\\](?<componentName>[a-z_-]+)[/\\]\k<componentName>\.[tj]s$/;
 
+/**
+ * This adds implicit style imports to the compiled component artifact.
+ */
 export function addStylesheetImports(ast: Program, state: ComponentMetaState, filepath: string) {
     const componentName = componentNamePattern.exec(filepath)?.groups?.componentName;
     if (!componentName) {
diff --git a/packages/@lwc/ssr-compiler/src/compile-js/types.ts b/packages/@lwc/ssr-compiler/src/compile-js/types.ts
index 0ba0109fd6..68ab3a3495 100644
--- a/packages/@lwc/ssr-compiler/src/compile-js/types.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-js/types.ts
@@ -11,18 +11,30 @@ import type { Node } from 'estree';
 export type Visitors = Parameters<typeof traverse<Node, ComponentMetaState>>[1];
 
 export interface ComponentMetaState {
+    // indicates whether the LightningElement subclass is found in the JS being traversed
     isLWC: boolean;
+    // indicates whether the LightningElement subclass includes a constructor method
     hasConstructor: boolean;
+    // indicates whether the subclass has a connectedCallback method
     hasConnectedCallback: boolean;
+    // indicates whether the subclass has a render method
     hasRenderMethod: boolean;
+    // indicates whether the subclass has a renderedCallback method
     hadRenderedCallback: boolean;
+    // indicates whether the subclass has a disconnectedCallback method
     hadDisconnectedCallback: boolean;
+    // indicates whether the subclass has a errorCallback method
     hadErrorCallback: boolean;
+    // the local name corresponding to the `LightningElement` import
     lightningElementIdentifier: string | null;
+    // the class name of the subclass
     lwcClassName: string | null;
+    // ties local variable names to explicitly-imported HTML templates
     tmplExplicitImports: Map<string, string> | null;
+    // ties local variable names to explicitly-imported CSS files
     cssExplicitImports: Map<string, string> | null;
+    // the set of variable names associated with explicitly imported CSS files
     staticStylesheetIds: Set<string> | null;
-    props: string[];
+    // tracks the aria-reflected attrs/props that show up in the JS code
     reflectedPropsInPlay: Set<string>;
 }
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/context.ts b/packages/@lwc/ssr-compiler/src/compile-template/context.ts
index 1d1c51a103..4400eaa462 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/context.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/context.ts
@@ -8,12 +8,6 @@
 import type { ModuleDeclaration as EsModuleDeclaration, Statement as EsStatement } from 'estree';
 import type { TemplateOpts, TransformerContext } from './types';
 
-function* reversed<T>(arr: T[]): Generator<T> {
-    for (let idx = arr.length - 1; idx > -1; idx--) {
-        yield arr[idx];
-    }
-}
-
 const identifierChars = 'abcdefghijklmnopqrstuvwxyz';
 
 function genId(n: number, prevChars = ''): string {
@@ -30,10 +24,6 @@ function* genIds() {
     }
 }
 
-export interface ContextOpts {
-    preserveComments: boolean;
-}
-
 export function createNewContext(templateOptions: TemplateOpts): {
     hoisted: Map<string, EsStatement | EsModuleDeclaration>;
     cxt: TransformerContext;
@@ -54,7 +44,7 @@ export function createNewContext(templateOptions: TemplateOpts): {
         if (!varName) {
             return false;
         }
-        for (const stackFrame of reversed(localVarStack)) {
+        for (const stackFrame of localVarStack) {
             if (stackFrame.has(varName)) {
                 return true;
             }
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/element.ts b/packages/@lwc/ssr-compiler/src/compile-template/element.ts
index 30bf95a08d..a957f11827 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/element.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/element.ts
@@ -8,7 +8,7 @@
 import { builders as b, is } from 'estree-toolkit';
 import { HTML_NAMESPACE, isVoidElement } from '@lwc/shared';
 import { esTemplateWithYield } from '../estemplate';
-import { irToEs } from './ir-to-es';
+import { irChildrenToEs } from './ir-to-es';
 import { bImportHtmlEscape, importHtmlEscapeKey, cleanStyleAttrVal } from './shared';
 
 import type {
@@ -70,9 +70,7 @@ function reorderAttributes(attrs: (IrAttribute | IrProperty)[]): (IrAttribute |
         return true;
     });
 
-    return [classAttr, styleAttr, ...boringAttrs].filter(
-        (el): el is NonNullable<IrAttribute> => el !== null
-    );
+    return [classAttr, styleAttr, ...boringAttrs].filter((el): el is IrAttribute => el !== null);
 }
 
 export const Element: Transformer<IrElement> = function Element(node, cxt): EsStatement[] {
@@ -81,16 +79,14 @@ export const Element: Transformer<IrElement> = function Element(node, cxt): EsSt
         ...node.properties,
     ]);
 
-    const yieldAttrsAndProps = attrsAndProps
-        .map((attr) => {
-            cxt.hoist(bImportHtmlEscape(), importHtmlEscapeKey);
-            if (attr.value.type === 'Literal') {
-                return yieldAttrOrPropLiteralValue(attr.name, attr.value);
-            } else {
-                return yieldAttrOrPropLiveValue(attr.name, attr.value);
-            }
-        })
-        .flat();
+    const yieldAttrsAndProps = attrsAndProps.flatMap((attr) => {
+        cxt.hoist(bImportHtmlEscape(), importHtmlEscapeKey);
+        if (attr.value.type === 'Literal') {
+            return yieldAttrOrPropLiteralValue(attr.name, attr.value);
+        } else {
+            return yieldAttrOrPropLiveValue(attr.name, attr.value);
+        }
+    });
 
     if (isVoidElement(node.name, HTML_NAMESPACE)) {
         return [bYield(b.literal(`<${node.name}`)), ...yieldAttrsAndProps, bYield(b.literal(`>`))];
@@ -100,7 +96,7 @@ export const Element: Transformer<IrElement> = function Element(node, cxt): EsSt
         bYield(b.literal(`<${node.name}`)),
         ...yieldAttrsAndProps,
         bYield(b.literal(`>`)),
-        ...node.children.map((child) => irToEs(child, cxt)).flat(),
+        ...irChildrenToEs(node.children, cxt),
         bYield(b.literal(`</${node.name}>`)),
     ].filter(Boolean);
 };
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/index.ts b/packages/@lwc/ssr-compiler/src/compile-template/index.ts
index 4920820ed8..683db6a5b2 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/index.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/index.ts
@@ -63,7 +63,7 @@ export default function compileTemplate(src: string, _filename: string) {
         'shadow';
     const astShadowModeBool = tmplRenderMode === 'light' ? b.literal(true) : b.literal(false);
 
-    const preserveComments = !!root!.directives.find(
+    const preserveComments = !!root.directives.find(
         (directive) => directive.name === 'PreserveComments'
     )?.value?.value;
 
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/ir-to-es.ts b/packages/@lwc/ssr-compiler/src/compile-template/ir-to-es.ts
index b1906188db..c949f0d26d 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/ir-to-es.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/ir-to-es.ts
@@ -15,12 +15,16 @@ import { If, IfBlock } from './if';
 import { Text } from './text';
 import { createNewContext } from './context';
 
-import type { Node as IrNode, Root as IrRoot } from '@lwc/template-compiler';
+import type {
+    ChildNode as IrChildNode,
+    Node as IrNode,
+    Root as IrRoot,
+} from '@lwc/template-compiler';
 import type { Statement as EsStatement } from 'estree';
 import type { TemplateOpts, Transformer, TransformerContext } from './types';
 
 const Root: Transformer<IrRoot> = function Root(node, cxt): EsStatement[] {
-    return node.children.map((child) => irToEs(child, cxt)).flat();
+    return irChildrenToEs(node.children, cxt);
 };
 
 const transformers: Record<string, Transformer> = {
@@ -38,6 +42,17 @@ const defaultTransformer: Transformer = (node: IrNode) => {
     throw new Error(`Unimplemented IR node: ${inspect(node)}`);
 };
 
+export function irChildrenToEs(children: IrChildNode[], cxt: TransformerContext): EsStatement[] {
+    const result = children.flatMap((child, idx) => {
+        cxt.prevSibling = children[idx - 1];
+        cxt.nextSibling = children[idx + 1];
+        return irToEs(child, cxt);
+    });
+    cxt.prevSibling = undefined;
+    cxt.nextSibling = undefined;
+    return result;
+}
+
 export function irToEs(node: IrNode, cxt: TransformerContext): EsStatement[] {
     const transformer = transformers[node.type] ?? defaultTransformer;
     return transformer(node, cxt);
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/shared.ts b/packages/@lwc/ssr-compiler/src/compile-template/shared.ts
index 7bd7574d1d..d82930944a 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/shared.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/shared.ts
@@ -6,6 +6,7 @@
  */
 
 import { is } from 'estree-toolkit';
+import { reservedKeywords } from '@lwc/shared';
 import { esTemplate } from '../estemplate';
 
 import type { ImportDeclaration as EsImportDeclaration, Statement as EsStatement } from 'estree';
@@ -22,58 +23,11 @@ export function cleanStyleAttrVal(styleAttrVal: string): string {
     return styleAttrVal.trim();
 }
 
-const reservedKeywords = new Set([
-    'NaN',
-    'arguments',
-    'break',
-    'case',
-    'catch',
-    'class',
-    'const',
-    'continue',
-    'debugger',
-    'default',
-    'delete',
-    'do',
-    'else',
-    'enum',
-    'eval',
-    'export',
-    'extends',
-    'false',
-    'finally',
-    'for',
-    'function',
-    'if',
-    'implements',
-    'import',
-    'in',
-    'instanceof',
-    'interface',
-    'let',
-    'new',
-    'null',
-    'package',
-    'private',
-    'protected',
-    'public',
-    'return',
-    'static',
-    'super',
-    'switch',
-    'this',
-    'throw',
-    'true',
-    'try',
-    'typeof',
-    'undefined',
-    'var',
-    'void',
-    'while',
-    'with',
-    'yield',
-]);
-
+// This is a mostly-correct regular expression will only match if the entire string
+// provided is a valid ECMAScript identifier. Its imperfections lie in the fact that
+// it will match strings like "export" when "export" is actually a reserved keyword
+// and therefore not a valid identifier. When combined with a check against reserved
+// keywords, it is a reliable test for whether a provided string is a valid identifier.
 const imperfectIdentifierMatcher = /^[_$a-zA-Z\xA0-\uFFFF][_$a-zA-Z0-9\xA0-\uFFFF]*$/;
 
 export const isValidIdentifier = (str: string) =>
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/text.ts b/packages/@lwc/ssr-compiler/src/compile-template/text.ts
index 730eed60bc..e560c9aa1d 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/text.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/text.ts
@@ -13,6 +13,7 @@ import { expressionIrToEs } from './expression';
 import type {
     Expression as EsExpression,
     Identifier as EsIdentifier,
+    Literal as EsLiteral,
     Statement as EsStatement,
 } from 'estree';
 import type {
@@ -27,16 +28,26 @@ const bYield = (expr: EsExpression) => b.expressionStatement(b.yieldExpression(e
 
 const bYieldEscapedString = esTemplateWithYield<
     EsStatement[],
-    [EsIdentifier, EsExpression, EsIdentifier, EsIdentifier, EsIdentifier, EsIdentifier]
+    [
+        EsIdentifier,
+        EsExpression,
+        EsIdentifier,
+        EsLiteral,
+        EsIdentifier,
+        EsIdentifier,
+        EsIdentifier,
+        EsIdentifier,
+        EsIdentifier
+    ]
 >`
     const ${is.identifier} = ${is.expression};
-    yield ${is.identifier} === ''
-        ? '\\u200D'
-        : htmlEscape(
-            typeof ${is.identifier} === 'string'
-                ? ${is.identifier}
-                : (${is.identifier} ?? '__UNEXPECTED_NULLISH_TEXT_CONTENT__').toString()
-        );
+    if (typeof ${is.identifier} === 'string') {
+        yield (${is.literal} && ${is.identifier} === '') ? '\\u200D' : htmlEscape(${is.identifier});
+    } else if (typeof ${is.identifier} === 'number') {
+        yield ${is.identifier}.toString();
+    } else {
+        yield htmlEscape((${is.identifier} ?? '').toString());
+    }
 `;
 
 function isLiteral(node: IrLiteral | IrExpression | IrComplexExpression): node is IrLiteral {
@@ -48,6 +59,11 @@ export const Text: Transformer<IrText> = function Text(node, cxt): EsStatement[]
         return [bYield(b.literal(node.value.value))];
     }
 
+    const isIsolatedTextNode = b.literal(
+        (!cxt.prevSibling || cxt.prevSibling.type !== 'Text') &&
+            (!cxt.nextSibling || cxt.nextSibling.type !== 'Text')
+    );
+
     const valueToYield = expressionIrToEs(node.value, cxt);
     cxt.hoist(bImportHtmlEscape(), importHtmlEscapeKey);
 
@@ -56,6 +72,9 @@ export const Text: Transformer<IrText> = function Text(node, cxt): EsStatement[]
         tempVariable,
         valueToYield,
         tempVariable,
+        isIsolatedTextNode,
+        tempVariable,
+        tempVariable,
         tempVariable,
         tempVariable,
         tempVariable
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/types.ts b/packages/@lwc/ssr-compiler/src/compile-template/types.ts
index bb93489f03..76a4fa4033 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/types.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/types.ts
@@ -20,6 +20,8 @@ export interface TransformerContext {
     isLocalVar: (varName: string | null | undefined) => boolean;
     getUniqueVar: () => string;
     templateOptions: TemplateOpts;
+    prevSibling?: IrNode;
+    nextSibling?: IrNode;
 }
 
 export interface TemplateOpts {
diff --git a/packages/@lwc/ssr-compiler/src/estemplate.ts b/packages/@lwc/ssr-compiler/src/estemplate.ts
index a545197705..0a1d429773 100644
--- a/packages/@lwc/ssr-compiler/src/estemplate.ts
+++ b/packages/@lwc/ssr-compiler/src/estemplate.ts
@@ -8,18 +8,23 @@
 import { traverse, Visitors } from 'estree-toolkit';
 import { parse } from 'acorn';
 import { produce } from 'immer';
-import type { Node, Program, FunctionDeclaration } from 'estree';
+import type {
+    Node as EsNode,
+    Program as EsProgram,
+    FunctionDeclaration as EsFunctionDeclaration,
+} from 'estree';
 
 export const placeholder = false;
+type ReplacementNode = EsNode | EsNode[] | null;
 
-type ReturnsBool = (node: Node | null) => boolean;
+type ReturnsBool = (node: EsNode | null) => boolean;
 export type Validator = ReturnsBool | typeof placeholder;
 
 const PLACEHOLDER_PREFIX = `__ESTEMPLATE_${Math.random().toString().slice(2)}_PLACEHOLDER__`;
 
 interface TraversalState {
     placeholderToValidator: Map<string, Validator>;
-    replacementNodes: (Node | Node[] | null)[];
+    replacementNodes: ReplacementNode[];
 }
 
 const visitors: Visitors<TraversalState> = {
@@ -62,7 +67,7 @@ const visitors: Visitors<TraversalState> = {
         ) {
             const key = path.node.value.slice(PLACEHOLDER_PREFIX.length);
             const validateReplacement = state.placeholderToValidator.get(key)!;
-            const replacementNode = state.replacementNodes[key as unknown as number] as Node;
+            const replacementNode = state.replacementNodes[key as unknown as number] as EsNode;
 
             if (validateReplacement && !validateReplacement(replacementNode)) {
                 throw new Error(`Validation failed for templated node of type ${path.node.type}`);
@@ -73,15 +78,12 @@ const visitors: Visitors<TraversalState> = {
     },
 };
 
-function esTemplateImpl<
-    ReturnType = Node,
-    ArgTypes extends (Node | Node[] | null)[] = (Node | Node[] | null)[]
->(
+function esTemplateImpl<RetType = EsNode, ArgTypes extends ReplacementNode[] = ReplacementNode[]>(
     javascriptSegments: TemplateStringsArray,
     validatorFns: Validator[],
     wrap?: (code: string) => string,
-    unwrap?: (node: ReturnType) => any
-): (...replacementNodes: ArgTypes) => ReturnType {
+    unwrap?: (node: RetType) => any
+): (...replacementNodes: ArgTypes) => RetType {
     let placeholderCount = 0;
     let parsableCode = javascriptSegments[0];
     validatorFns.reverse();
@@ -100,68 +102,66 @@ function esTemplateImpl<
         parsableCode = wrap(parsableCode);
     }
 
-    let originalAst = parse(parsableCode, {
+    const originalAstProgram = parse(parsableCode, {
         ecmaVersion: 2022,
         allowAwaitOutsideFunction: true,
         allowReturnOutsideFunction: true,
         allowSuperOutsideMethod: true,
         allowImportExportEverywhere: true,
         locations: false,
-    }) as Node;
+    }) as EsNode as EsProgram;
+
+    let originalAst: EsNode | EsNode[];
 
-    const originalAstProgram = originalAst as Program;
     const finalCharacter = javascriptSegments.at(-1)?.trimEnd()?.at(-1);
-    if (
-        originalAstProgram.body.length === 1 &&
-        originalAstProgram.body[0].type === 'ExpressionStatement' &&
-        finalCharacter !== ';'
-    ) {
-        originalAst = originalAstProgram.body[0].expression;
+    if (originalAstProgram.body.length === 1) {
+        originalAst =
+            finalCharacter === ';' && originalAstProgram.body[0].type === 'ExpressionStatement'
+                ? (originalAst = originalAstProgram.body[0].expression)
+                : (originalAst = originalAstProgram.body[0]);
     } else {
-        originalAst = originalAstProgram.body[0];
+        originalAst = originalAstProgram.body;
     }
 
     // Turns Acorn AST objects into POJOs, for use with Immer.
     originalAst = JSON.parse(JSON.stringify(originalAst));
 
-    return function templatedAst(...replacementNodes: ArgTypes): ReturnType {
+    return function templatedAst(...replacementNodes: ArgTypes): RetType {
         const result = produce(originalAst, (astDraft) =>
             traverse(astDraft, visitors, {
                 placeholderToValidator,
                 replacementNodes,
             })
-        ) as ReturnType;
+        ) as RetType;
         return unwrap ? unwrap(result) : result;
     };
 }
 
 export function esTemplate<
-    ReturnType = Node,
-    ArgTypes extends (Node | Node[] | null)[] = (Node | Node[] | null)[]
+    RetType = EsNode,
+    ArgTypes extends ReplacementNode[] = ReplacementNode[]
 >(
     javascriptSegments: TemplateStringsArray,
     ...validatorFns: Validator[]
-): (...replacementNodes: ArgTypes) => ReturnType {
+): (...replacementNodes: ArgTypes) => RetType {
     return esTemplateImpl(javascriptSegments, validatorFns);
 }
 
 export function esTemplateWithYield<
-    ReturnType = Node,
-    ArgTypes extends (Node | Node[] | null)[] = (Node | Node[] | null)[]
+    RetType = EsNode,
+    ArgTypes extends ReplacementNode[] = ReplacementNode[]
 >(
     javascriptSegments: TemplateStringsArray,
     ...validatorFns: Validator[]
-): (...replacementNodes: ArgTypes) => ReturnType {
+): (...replacementNodes: ArgTypes) => RetType {
     const wrap = (code: string) => `function* placeholder() {${code}}`;
-    const unwrap = (node: FunctionDeclaration) =>
-        node.body.body.length === 1
-            ? (node.body.body[0] as ReturnType)
-            : (node.body.body as ReturnType);
+    const unwrap = (node: EsFunctionDeclaration) =>
+        node.body.body.length === 1 ? (node.body.body[0] as RetType) : (node.body.body as RetType);
 
-    return esTemplateImpl<FunctionDeclaration>(
+    return esTemplateImpl<EsFunctionDeclaration>(
         javascriptSegments,
         validatorFns,
         wrap,
         unwrap
-    ) as unknown as (...replacementNodes: ArgTypes) => ReturnType;
+    ) as unknown as (...replacementNodes: ArgTypes) => RetType;
 }
diff --git a/packages/@lwc/ssr-compiler/src/estree/builders.ts b/packages/@lwc/ssr-compiler/src/estree/builders.ts
index f91e174437..dc71c548d2 100644
--- a/packages/@lwc/ssr-compiler/src/estree/builders.ts
+++ b/packages/@lwc/ssr-compiler/src/estree/builders.ts
@@ -9,10 +9,8 @@ import { is } from 'estree-toolkit';
 import { esTemplate } from '../estemplate';
 import { isStringLiteral } from './validators';
 
-import type { ImportDeclaration, NewExpression } from 'estree';
+import type { ImportDeclaration } from 'estree';
 
 export const bImportDeclaration = esTemplate<ImportDeclaration>`
     import ${is.identifier} from "${isStringLiteral}";
 `;
-
-export const bInstantiate = esTemplate<NewExpression>`new ${is.identifier}()`;
diff --git a/packages/@lwc/ssr-compiler/src/estree/validators.ts b/packages/@lwc/ssr-compiler/src/estree/validators.ts
index d9fde40769..4e306ef684 100644
--- a/packages/@lwc/ssr-compiler/src/estree/validators.ts
+++ b/packages/@lwc/ssr-compiler/src/estree/validators.ts
@@ -10,9 +10,6 @@ import { is } from 'estree-toolkit';
 import type { Node } from 'estree';
 import type { Validator } from '../estemplate';
 
-export const isNullOrInstantiation = (node: Node | null) =>
-    (is.literal(node) && node.value === null) || is.newExpression(node);
-
 export const isStringLiteral = (node: Node | null) =>
     is.literal(node) && typeof node.value === 'string';
 
diff --git a/packages/@lwc/ssr-compiler/src/generator.ts b/packages/@lwc/ssr-compiler/src/generator.ts
deleted file mode 100644
index 1ca951d633..0000000000
--- a/packages/@lwc/ssr-compiler/src/generator.ts
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * Copyright (c) 2024, salesforce.com, inc.
- * All rights reserved.
- * SPDX-License-Identifier: MIT
- * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
- */
-
-import type { Instruction } from './shared';
-import type { Program } from 'estree';
-
-export function bytecodeToEsTree(_instructions: Generator<Instruction>): Program {
-    return {
-        type: 'Program',
-        body: [],
-        sourceType: 'module',
-    };
-}
diff --git a/packages/@lwc/ssr-compiler/src/index.ts b/packages/@lwc/ssr-compiler/src/index.ts
index cf2e153286..59becc2fdd 100644
--- a/packages/@lwc/ssr-compiler/src/index.ts
+++ b/packages/@lwc/ssr-compiler/src/index.ts
@@ -8,8 +8,6 @@
 import compileJS from './compile-js';
 import compileTemplate from './compile-template';
 
-import type { GenerateMarkupFn } from './shared';
-
 interface TransformOptions {}
 
 export interface CompilationResult {
@@ -32,22 +30,5 @@ export function compileTemplateForSSR(
     _options: TransformOptions
 ): CompilationResult {
     const { code } = compileTemplate(src, filename);
-    return {
-        code,
-        map: undefined,
-    };
-}
-
-export async function serverSideRenderComponent(
-    tagName: string,
-    compiledGenerateMarkup: GenerateMarkupFn,
-    props: Record<string, any>
-): Promise<string> {
-    let markup = '';
-
-    for await (const segment of compiledGenerateMarkup(tagName, props, null, null)) {
-        markup += segment;
-    }
-
-    return markup;
+    return { code, map: undefined };
 }
diff --git a/packages/@lwc/ssr-compiler/src/shared.ts b/packages/@lwc/ssr-compiler/src/shared.ts
index 008f64d5d9..8d25172130 100644
--- a/packages/@lwc/ssr-compiler/src/shared.ts
+++ b/packages/@lwc/ssr-compiler/src/shared.ts
@@ -55,12 +55,3 @@ export interface IHoistImport {
 export interface IHoistInstantiation {
     kind: 'hoistInstantiation';
 }
-
-export type GenerateMarkupFn = (
-    tagName: string,
-    props: Record<string, any> | null,
-    attrs: Record<string, any> | null,
-    slotted: Record<number | string, AsyncGenerator<string>> | null
-) => AsyncGenerator<string>;
-
-export type TemplateFn = (Ctor: any, instance: any | null) => AsyncGenerator<string>;
diff --git a/packages/@lwc/ssr-runtime/package.json b/packages/@lwc/ssr-runtime/package.json
index dc90f998c1..e1886a9726 100644
--- a/packages/@lwc/ssr-runtime/package.json
+++ b/packages/@lwc/ssr-runtime/package.json
@@ -7,7 +7,9 @@
     "version": "6.5.3",
     "description": "Runtime complement to @lwc/ssr-compiler",
     "keywords": [
-        "lwc"
+        "lwc",
+        "runtime",
+        "ssr"
     ],
     "homepage": "https://lwc.dev",
     "repository": {
@@ -30,8 +32,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/ssr-runtime/src/index.ts b/packages/@lwc/ssr-runtime/src/index.ts
index ff3fd7fa0c..cdbb0cf69c 100644
--- a/packages/@lwc/ssr-runtime/src/index.ts
+++ b/packages/@lwc/ssr-runtime/src/index.ts
@@ -7,11 +7,9 @@
 
 const MULTI_SPACE = /\s+/g;
 
-type Attributes = Record<string, string>;
+type Attributes = Record<string, string | true>;
 
-type LightningElementConstructor = typeof LightningElement & {
-    renderMode?: 'light' | 'shadow';
-};
+type LightningElementConstructor = typeof LightningElement;
 
 class ClassList {
     el: LightningElement;
@@ -71,10 +69,12 @@ class ClassList {
 }
 
 export class LightningElement {
+    static renderMode?: 'light' | 'shadow';
+
     isConnected = false;
     className = '';
     // TODO [W-14977927]: protect internals from userland
-    __attrs?: Record<string, string>;
+    __attrs?: Attributes;
     __classList: ClassList | null = null;
 
     constructor(propsAvailableAtConstruction: Record<string, any>) {
@@ -95,7 +95,7 @@ export class LightningElement {
         for (const reflectedPropName of reflectedProps) {
             Object.defineProperty(this, reflectedPropName, {
                 get() {
-                    return props[reflectedPropName];
+                    return props[reflectedPropName] ?? null;
                 },
                 set(newValue) {
                     props[reflectedPropName] = newValue;
@@ -122,8 +122,9 @@ export class LightningElement {
         return (this.__classList = new ClassList(this));
     }
 
-    getAttribute(attrName: string) {
-        return this.__attrs?.[attrName] ?? null;
+    getAttribute(attrName: string): string | null {
+        const value = this.__attrs?.[attrName];
+        return value === true ? '' : value ?? null;
     }
 }
 
@@ -153,9 +154,27 @@ export function* fallbackTmpl(
     _instance: unknown
 ) {
     if (Cmp.renderMode !== 'light') {
-        yield '<template shadowrootmode="open">';
+        yield '<template shadowrootmode="open"></template>';
     }
-    if (Cmp.renderMode !== 'light') {
-        yield '</template>';
+}
+
+export type GenerateMarkupFn = (
+    tagName: string,
+    props: Record<string, any> | null,
+    attrs: Attributes | null,
+    slotted: Record<number | string, AsyncGenerator<string>> | null
+) => AsyncGenerator<string>;
+
+export async function serverSideRenderComponent(
+    tagName: string,
+    compiledGenerateMarkup: GenerateMarkupFn,
+    props: Record<string, any>
+): Promise<string> {
+    let markup = '';
+
+    for await (const segment of compiledGenerateMarkup(tagName, props, null, null)) {
+        markup += segment;
     }
+
+    return markup;
 }
diff --git a/packages/@lwc/style-compiler/package.json b/packages/@lwc/style-compiler/package.json
index 030b3f8cf2..19a55e8158 100644
--- a/packages/@lwc/style-compiler/package.json
+++ b/packages/@lwc/style-compiler/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/synthetic-shadow/package.json b/packages/@lwc/synthetic-shadow/package.json
index 14a4f54a03..79eb354b5e 100644
--- a/packages/@lwc/synthetic-shadow/package.json
+++ b/packages/@lwc/synthetic-shadow/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/template-compiler/package.json b/packages/@lwc/template-compiler/package.json
index 2ad77f0018..f402cc085c 100644
--- a/packages/@lwc/template-compiler/package.json
+++ b/packages/@lwc/template-compiler/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/packages/@lwc/wire-service/package.json b/packages/@lwc/wire-service/package.json
index 03c47d0e35..ba26e73470 100644
--- a/packages/@lwc/wire-service/package.json
+++ b/packages/@lwc/wire-service/package.json
@@ -30,8 +30,7 @@
     ],
     "scripts": {
         "build": "rollup --config ../../../scripts/rollup/rollup.config.js",
-        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen",
-        "test": "jest ./src/**/*.spec.ts"
+        "dev": "rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen"
     },
     "nx": {
         "targets": {
diff --git a/scripts/rollup/rollup.config.js b/scripts/rollup/rollup.config.js
index 7ea1ae770b..5b4706fe1d 100644
--- a/scripts/rollup/rollup.config.js
+++ b/scripts/rollup/rollup.config.js
@@ -44,10 +44,6 @@ if (packageName === '@lwc/synthetic-shadow') {
 }
 
 const onwarn = ({ code, message }) => {
-    if (code === 'INVALID_ANNOTATION') {
-        // Not sure why the PURE annotations are broken.
-        return;
-    }
     if (!process.env.ROLLUP_WATCH && code !== 'CIRCULAR_DEPENDENCY') {
         throw new Error(message);
     }
diff --git a/scripts/tasks/check-and-rewrite-package-json.js b/scripts/tasks/check-and-rewrite-package-json.js
index ef99970b57..e0931434fe 100644
--- a/scripts/tasks/check-and-rewrite-package-json.js
+++ b/scripts/tasks/check-and-rewrite-package-json.js
@@ -81,8 +81,6 @@ for (const dir of directories) {
         scripts: {
             build: 'rollup --config ../../../scripts/rollup/rollup.config.js',
             dev: 'rollup  --config ../../../scripts/rollup/rollup.config.js --watch --no-watch.clearScreen',
-            test: name === '@lwc/ssr-compiler' ? undefined : 'jest ./src/**/*.spec.ts',
-            'test-manual': name === '@lwc/ssr-compiler' ? 'jest ./src/**/*.spec.ts' : undefined,
         },
         nx: {
             targets: {
diff --git a/yarn.lock b/yarn.lock
index e39baa8a32..a0ea7364da 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2565,16 +2565,16 @@ acorn-walk@^8.0.2:
   resolved "https://registry.yarnpkg.com/acorn-walk/-/acorn-walk-8.3.2.tgz#7703af9415f1b6db9315d6895503862e231d34aa"
   integrity sha512-cjkyv4OtNCIeqhHrfS81QWXoCBPExR/J62oyEqepVw8WaQeSqpW2uhuLPh1m9eWhDuOo/jUXVTlifvesOWp/4A==
 
+acorn@8.10.0:
+  version "8.10.0"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-8.10.0.tgz#8be5b3907a67221a81ab23c7889c4c5526b62ec5"
+  integrity sha512-F0SAmZ8iUtS//m8DmCTA0jlh6TDKkHQyK6xc6V4KDTyZKA9dnvX9/3sRTVQrWm79glUAZbnmmNcdYwUIHWVybw==
+
 acorn@^8.1.0, acorn@^8.8.1, acorn@^8.8.2, acorn@^8.9.0, acorn@~8.11.3:
   version "8.11.3"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-8.11.3.tgz#71e0b14e13a4ec160724b38fb7b0f233b1b81d7a"
   integrity sha512-Y9rRfJG5jcKOE0CLisYbojUjIrIEE7AGMzA/Sm4BslANhbS+cDMpgBdcPT91oJ7OuJ9hYJBx59RjbhxVnrF8Xg==
 
-acorn@~8.10.0:
-  version "8.10.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-8.10.0.tgz#8be5b3907a67221a81ab23c7889c4c5526b62ec5"
-  integrity sha512-F0SAmZ8iUtS//m8DmCTA0jlh6TDKkHQyK6xc6V4KDTyZKA9dnvX9/3sRTVQrWm79glUAZbnmmNcdYwUIHWVybw==
-
 agent-base@6, agent-base@^6.0.2:
   version "6.0.2"
   resolved "https://registry.yarnpkg.com/agent-base/-/agent-base-6.0.2.tgz#49fff58577cfee3f37176feab4c22e00f86d7f77"