diff --git a/commitlint.config.js b/commitlint.config.js
index 8ae4701ab0..ce88a47eec 100644
--- a/commitlint.config.js
+++ b/commitlint.config.js
@@ -32,6 +32,7 @@ export default {
         'progress',
         'radio',
         'ripple',
+        'sass-ext',
         'select',
         'slider',
         'switch',
diff --git a/docs/sass/sass-ext.md b/docs/sass/sass-ext.md
new file mode 100644
index 0000000000..c5ecc7c616
--- /dev/null
+++ b/docs/sass/sass-ext.md
@@ -0,0 +1,746 @@
+<!-- go/g3mark-in-g3doc -->
+
+# `sass/ext`
+
+<!--*
+# Document freshness: For more information, see go/fresh-source.
+freshness: { owner: 'lizmitchell' reviewed: '2025-11-25' }
+tag: 'docType:reference'
+*-->
+
+go/sass-ext
+
+A collection of useful Sass modules that extend and complement the functionality
+provided by built-in `sass:*` modules.
+
+<!-- [TOC] -->
+
+## Usage
+
+These Sass utilities are intended to reduce boilerplate for common Sass
+metaprogramming use cases, such as type checking.
+
+```scss
+@use '@material/web/sass/ext/assert';
+@use '@material/web/sass/ext/map_ext';
+
+@mixin theme($values) {
+  $values: assert.is-type($values, 'map');
+  --primary: #{map_ext.get-strict($values, 'primary')};
+  --secondary: #{map_ext.get-strict($values, 'secondary')};
+  --tertiary: #{map_ext.get-strict($values, 'tertiary')};
+}
+```
+
+The same logic using built-in modules requires more boilerplate.
+
+```scss
+@use 'sass:map';
+@use 'sass:meta';
+
+@mixin theme($values) {
+  @if meta.type-of($values) != 'map' {
+    @error 'Argument is not a map: #{meta.inspect($values)}';
+  }
+  @if not map.has-key($values, 'primary') {
+    @error 'Map is missing key "primary": #{meta.inspect($values)}';
+  }
+  @if not map.has-key($values, 'secondary') {
+    @error 'Map is missing key "secondary": #{meta.inspect($values)}';
+  }
+  @if not map.has-key($values, 'tertiary') {
+    @error 'Map is missing key "tertiary": #{meta.inspect($values)}';
+  }
+
+  --primary: #{map.get($values, 'primary')};
+  --secondary: #{map.get($values, 'secondary')};
+  --tertiary: #{map.get($values, 'tertiary')};
+}
+```
+
+## Who should use `sass/ext`?
+
+These utilities should be used by Sass libraries that need to perform
+*repetitive* and *complex* Sass metaprogramming logic.
+
+Prefer using built-in Sass functionality for simple use cases where `sass/ext`
+would not reduce complexity.
+
+```scss {.bad}
+// Using sass/ext here does not reduce boilerplate, and adds another API to
+// learn and maintain.
+@use '@material/web/sass/ext/type';
+
+@function value-or-default($value, $default) {
+  @if type.matches($value, 'null') {
+    @return $default;
+  }
+  @return $value;
+}
+```
+
+```scss {.good}
+// For simple use cases, built-in Sass functionality should be preferred.
+@function value-or-default($value, $default) {
+  @if $value == null {
+    @return $default;
+  }
+  @return $value;
+}
+```
+
+<!-- mdformat off(autogenerated docs) -->
+<!-- generated_docs_start -->
+
+## `assert`
+
+### `is-type` {#assert.is-type}
+
+```scss
+assert.is-type($arg, $type, $message, $source)
+
+/// @param {*} $arg - The argument to check.
+/// @param {string} $type - The string type to assert the argument matches. Multiple types may be separated by '|'.
+/// @param {string} $message - Optional custom error message.
+/// @param {string} $source - Optional source of the error message.
+/// @return {*} The argument if it matches the type string.
+/// @throw Error if the argument does not match the type string.
+```
+
+Asserts that the argument is a specific type. If it is, the argument is
+returned, otherwise an error is thrown.
+
+```scss
+@mixin multiply($a, $b) {
+  $a: assert.is-type($a, 'number');
+  $b: assert.is-type($b, 'number');
+  @return $a * $b;
+}
+
+@function is-empty($value) {
+  $value: assert.is-type(
+    $value,
+    'list|map|null',
+    $message: '$value must be a list, map, or null',
+    $source: 'is-empty'
+  );
+  @return $value and list.length($value) == 0;
+}
+```
+
+### `not-type` {#assert.not-type}
+
+```scss
+assert.not-type($arg, $type, $message, $source)
+
+/// @param {*} $arg - The argument to check.
+/// @param {string} $type - The string type to assert the argument does not match. Multiple types may be separated by '|'.
+/// @param {string} $message - Optional custom error message.
+/// @param {string} $source - Optional source of the error message.
+/// @return {*} The argument if it does not match the type string.
+/// @throw Error if the argument matches the type string.
+```
+
+Asserts that the argument is not a specific type. The argument is returned
+if it does not match. An error is thrown if the argument matches the type.
+
+```scss
+@function get-strict($map, $key) {
+  @return assert.not-type(
+    map.get($map, $key),
+    'null',
+    $message: 'Key must be in the map'
+  );
+}
+```
+
+## `list_ext`
+
+### `difference` {#list_ext.difference}
+
+```scss
+list_ext.difference($listA, $listB) //=> list
+
+/// @param {list} $listA - The first list to compare.
+/// @param {list} $listB - The second list to compare.
+/// @return {list} All items in $listA that are not in $listB.
+```
+
+Returns the difference between two lists.
+
+```scss
+$listA: ('apple', 'banana', 'cherry', 'date');
+$listB: ('banana', 'cherry', 'apple');
+$listC: ('apple', 'banana', 'date');
+
+@debug list_ext.difference($listA, $listB); // ('date')
+@debug list_ext.difference($listA, $listC); // ('cherry')
+```
+
+### `are-equal` {#list_ext.are-equal}
+
+```scss
+list_ext.are-equal($listA, $listB) //=> boolean
+
+/// @param {list} $listA - The first list to compare.
+/// @param {list} $listB - The second list to compare.
+/// @return {boolean} `true` if the lists contain the same elements, otherwise `false`.
+```
+
+Checks if two lists contain the same elements, regardless of their order.
+
+The function iterates through each list and verifies that every element in
+one list is present in the other. The order of elements does not affect the
+result.
+
+```scss
+$listA: ('apple', 'banana', 'cherry');
+$listB: ('banana', 'cherry', 'apple');
+$listC: ('apple', 'banana', 'date');
+
+@debug list_ext.are-equal($listA, $listB); // true
+@debug list_ext.are-equal($listA, $listC); // false
+```
+
+### `intersection` {#list_ext.intersection}
+
+```scss
+list_ext.intersection($listA, $listB) //=> list
+
+/// @param {list} $listA - The first list to compare.
+/// @param {list} $listB - The second list to compare.
+/// @return {list} All items in $listA that are also in $listB.
+```
+
+Returns the intersection of two lists.
+
+```scss
+$listA: ('apple', 'banana', 'cherry', 'date');
+$listB: ('banana', 'cherry', 'apple');
+$listC: ('apple', 'banana', 'date');
+
+@debug list_ext.intersection($listA, $listB); // ('apple', 'banana', 'cherry')
+@debug list_ext.intersection($listA, $listC); // ('apple', 'banana')
+```
+
+## `map_ext`
+
+### `get-strict` {#map_ext.get-strict}
+
+```scss
+map_ext.get-strict($map, $key, $keys)
+
+/// @param {map} $map - The map to retrieve the value from.
+/// @param {string} $key - The key of the value to retrieve.
+/// @param {list} $keys - Additional keys to retrieve deeply nested values.
+/// @return {*} The value at the given key.
+/// @throw Error if the key does not exist in the map.
+```
+
+The same as `map.get()` but throws an error if the key is not found.
+
+This is useful over `map.get()` when using Sass maps like records, where
+the key is expected to exist.
+
+```scss
+$map: (
+  'name': 'foo',
+  'value': blue,
+);
+
+@debug map_ext.get-strict($map, 'name'); // 'foo'
+@debug map_ext.get-strict($map, 'bar'); // ERROR: Key "bar" expected but not found in $map: ('name': 'foo', 'value': blue)
+```
+
+### `split` {#map_ext.split}
+
+```scss
+map_ext.split($map, $keys) //=> list
+
+/// @param {map} $map - The Map to split.
+/// @param {list} $keys - List of keys to split the Map by.
+/// @return {list} A List pair with two new Maps: the first with the keys provided, and the second with the remaining keys.
+```
+
+Splits a Map and returns a List pair with two new Maps: the first with the
+provided keys and the second without.
+
+```scss
+$map: (
+  'focus': blue,
+  'focus-within': blue,
+  'hover': teal,
+  'active': green,
+);
+
+$pair: map_ext.split($map, ('focus', 'focus-within'));
+
+$map-with-focus-keys: list.nth($pair, 1);
+@debug $map-with-focus-keys; // ('focus': blue, 'focus-within': blue)
+
+$map-with-remaining-keys: list.nth($pair, 2);
+@debug $map-with-remaining-keys; // ('hover': teal, 'active': green)
+```
+
+### `pick` {#map_ext.pick}
+
+```scss
+map_ext.pick($map, $keys) //=> map
+
+/// @param {map} $map - The Map to split.
+/// @param {list} $keys - List of keys to include in the new Map.
+/// @return {map} Map with only the keys provided.
+```
+
+Splits a Map and returns a new Map that only includes the provided keys.
+
+```scss
+$map: (
+  'focus': blue,
+  'focus-within': blue,
+  'hover': teal,
+  'active': green,
+);
+
+$map-with-focus-keys: map_ext.pick($map, ('focus', 'focus-within'));
+@debug $map-with-focus-keys; // ('focus': blue, 'focus-within': blue)
+```
+
+### `omit` {#map_ext.omit}
+
+```scss
+map_ext.omit($map, $keys) //=> map
+
+/// @param {map} $map - The Map to split.
+/// @param {list} $keys - List of keys to exclude from the new Map.
+/// @return {map} Map without the keys provided.
+```
+
+Splits a Map and returns a new Map that excludes the provided keys.
+
+```scss
+$map: (
+  'focus': blue,
+  'focus-within': blue,
+  'hover': teal,
+  'active': green,
+);
+
+$map-without-focus-keys: map_ext.omit($map, ('focus', 'focus-within'));
+@debug $map-without-focus-keys; // ('hover': teal, 'active': green)
+```
+
+### `rename-keys` {#map_ext.rename-keys}
+
+```scss
+map_ext.rename-keys($map, $keys-to-rename) //=> map
+
+/// @param {map} $map - The map to rename keys within.
+/// @param {map} $keys-to-rename - A map of keys and their new names.
+/// @return {map} The map with any matching keys renamed.
+```
+
+Returns the given map with any matching keys renamed according to the
+provided Map of keys to rename.
+
+```scss
+$map: ('foo': red);
+
+$new-map: map_ext.rename-keys($map, ('foo': 'bar'));
+@debug $new-map; // ('bar': red)
+```
+
+### `difference` {#map_ext.difference}
+
+```scss
+map_ext.difference($mapA, $mapB) //=> list
+
+/// @param {map} $mapA - The reference map.
+/// @param {map} $mapB - The map to compare against the reference.
+/// @return {list} A list of keys where $mapB diverges from $mapA.
+```
+
+Returns a list of keys where $mapB diverges from $mapA.
+Divergence occurs when:
+  1. A key exists in $mapB but not in $mapA.
+  2. A key exists in both maps but with different values.
+
+```scss
+$mapA: ('foo': red, 'bar': yellow, 'baz': 10);
+$mapB: ('foo': red, 'bar': green,  'baz': 10, 'fooBar': blue);
+
+$differences: map_ext.difference($mapA, $mapB);
+@debug $differences; // ('bar', 'fooBar')
+```
+
+## `string_ext`
+
+### `starts-with` {#string_ext.starts-with}
+
+```scss
+string_ext.starts-with($string, $prefix) //=> boolean
+
+/// @param {string} $string - The string to test.
+/// @param {string} $prefix - The prefix to check.
+/// @return {boolean} True if the string starts with the given prefix.
+```
+
+Checks if a string starts with a given prefix.
+
+```scss
+@debug string_ext.starts-with('var(--foo)', 'var('); // true
+```
+
+### `ends-with` {#string_ext.ends-with}
+
+```scss
+string_ext.ends-with($string, $suffix) //=> boolean
+
+/// @param {string} $string - The string to test.
+/// @param {string} $suffix - The suffix to check.
+/// @return {boolean} True if the string ends with the given suffix.
+```
+
+Checks if a string ends with a given suffix.
+
+```scss
+@debug string_ext.ends-with('var(--foo)', ')'); // true
+```
+
+### `trim-start` {#string_ext.trim-start}
+
+```scss
+string_ext.trim-start($string) //=> string
+
+/// @param {string} $string - The string to trim.
+/// @return {string} The string with whitespace trimmed from the start.
+```
+
+Trims leading whitespace from the start of a string.
+
+```scss
+@debug string_ext.trim-start('  foo bar  '); // "foo bar  "
+```
+
+### `trim-end` {#string_ext.trim-end}
+
+```scss
+string_ext.trim-end($string) //=> string
+
+/// @param {string} $string - The string to trim.
+/// @return {string} The string with trailing whitespace trimmed from the end.
+```
+
+Trims trailing whitespace from the end of a string.
+
+```scss
+@debug string_ext.trim-end('  foo bar  '); // "  foo bar"
+```
+
+### `trim` {#string_ext.trim}
+
+```scss
+string_ext.trim($string) //=> string
+
+/// @param {string} $string - The string to trim.
+/// @return {string} The string with leading and trailing whitespace trimmed.
+```
+
+Trims leading and trailing whitespace from a string.
+
+```scss
+@debug string_ext.trim('  foo bar  '); // "foo bar"
+```
+
+### `replace` {#string_ext.replace}
+
+```scss
+string_ext.replace($string, $pattern, $replacement) //=> string
+
+/// @param {string} $string - The string to be searched.
+/// @param {string} $pattern - The pattern to search for.
+/// @param {string} $replacement - The value to replace the pattern.
+/// @return {string} The string with the first match of pattern replaced by the replacement or the initial string itself.
+```
+
+Returns a new string with the first match of a pattern replaced by a given
+string.
+
+```scss
+@debug string_ext.replace('foo bar baz', 'bar', 'quux'); // "foo quux baz"
+```
+
+### `replace-all` {#string_ext.replace-all}
+
+```scss
+string_ext.replace-all($string, $pattern, $replacement) //=> string
+
+/// @param {string} $string - The string to be searched.
+/// @param {string} $pattern - The pattern to search for.
+/// @param {string} $replacement - The value to replace the pattern.
+/// @return {string} The string with all matches of pattern replaced by the replacement or the initial string itself.
+```
+
+Returns a new string with all matches of a pattern replaced by a given
+string.
+
+```scss
+@debug string_ext.replace-all('foo bar baz', 'ba', 'qua'); // "foo quar quaz"
+```
+
+### `replace-start` {#string_ext.replace-start}
+
+```scss
+string_ext.replace-start($string, $prefix, $replacement) //=> string
+
+/// @param {string} $string - The string to be searched.
+/// @param {string} $prefix - The prefix string to replace.
+/// @param {string} $replacement - The value to replace the prefix.
+/// @return {string} The string with the prefix replaced.
+```
+
+Returns a new string that replaces a prefix at the start of the string.
+
+```scss
+@debug string_ext.replace-start('var(--foo)', 'var(', ''); // "--foo)"
+```
+
+### `replace-end` {#string_ext.replace-end}
+
+```scss
+string_ext.replace-end($string, $suffix, $replacement) //=> string
+
+/// @param {string} $string - The string to be searched.
+/// @param {string} $suffix - The suffix string to replace.
+/// @param {string} $replacement - The value to replace the suffix.
+/// @return {string} The string with the suffix trimmed from the end.
+```
+
+Returns a new string that replaces a suffix at the end of the string.
+
+```scss
+@debug string_ext.replace-end('var(--foo)', ')', ''); // "var(--foo"
+```
+
+## `throw`
+
+### `get-error` {#throw.get-error}
+
+```scss
+throw.get-error($error, $errors)
+
+/// @param {*} $error - The value to check.
+/// @param {list} $errors - Additional values to check. Useful for checking multiple errors at the same time.
+/// @return {string|boolean} The error string if any value is an error, or false otherwise.
+```
+
+Returns false if none of the given values are error strings, or returns an
+error string if any value has an error.
+
+This is used to support testing error behavior with `sass-true`, since
+`@error` messages cannot be caught at build time.
+
+```scss
+// A function that may return an "ERROR:" string in a test.
+@function get-value($map, $key) {
+  @if meta.type-of($map) != 'map' {
+    // Identical to `@error 'ERROR: Arg is not a map'` outside of tests.
+    @return throw.error('Arg is not a map');
+  }
+  @return map.get($map, $key);
+}
+
+// A function that needs to handle potential errors from other functions.
+@function mix-primary-on-surface($values) {
+  $primary: get-value($values, 'primary');
+  $surface: get-value($values, 'surface');
+  $error: throw.get-error($primary, $surface);
+  @if $error {
+    // Return early to guard logic against additional errors since
+    // $primary or $surface may be a string instead of a color.
+    @return $error;
+  }
+
+  @return color.mix($primary, $surface, 10%);
+}
+```
+
+Note: `throw.error()` and `throw.get-error()` are only useful when testing
+error behavior using `sass-true`. If you are not testing a function, use
+`@error` instead.
+
+```scss
+// In a `sass-true` test, `throw.get-error()` can be used to assert that
+// an error is thrown.
+@use 'true' as test with ($catch-errors: true);
+
+@include test.describe('module.get-value()') {
+  @include test.it('throws an error if the value is not a map') {
+    $result: module.get-value('not a map', 'primary');
+    @include test.assert-truthy(throw.get-error($result), '$result is an error');
+  }
+}
+```
+
+## `type`
+
+### `matches` {#type.matches}
+
+```scss
+type.matches($value, $type-string) //=> boolean
+
+/// @param {*} $value - The value to check the type of.
+/// @param {string} $type-string - The type to check. May be multiple types separated by `|`.
+/// @return {boolean} True if the value matches the type string.
+```
+
+Returns true if the given value matches the provided type string.
+
+The type string supports multiple types separated by `|`, such as
+`'string|null'`. Type options are any values returned by `meta.type-of()`.
+
+```scss
+@function is-empty($value) {
+  @if type.matches($value, 'list|map') {
+    @return list.length($value) == 0;
+  }
+  @if type.matches($value, 'string') {
+    @return $value == '';
+  }
+  @return type.matches($value, 'null');
+}
+```
+
+## `var`
+
+### `create` {#var.create}
+
+```scss
+var.create($name, $fallback) //=> string
+
+/// @param {string} $name - The name of the custom property.
+/// @param {*} $fallback [null] - Optional `var()` fallback value.
+/// @return {string} A custom property `var()` string.
+```
+
+Creates a custom property `var()` string.
+
+```scss
+@debug var.create(--foo); // "var(--foo)"
+@debug var.create(--foo, 8px); // "var(--foo, 8px)"
+```
+
+### `name` {#var.name}
+
+```scss
+var.name($var) //=> string
+
+/// @param {string} $var - A custom property `var()` string.
+/// @return {string} The custom property variable name.
+/// @throw If the value is not a custom property.
+```
+
+Returns the custom property variable name of `var()` string.
+
+```scss
+$var: var(--foo);
+@debug var.name($var); // "--foo"
+```
+
+### `fallback` {#var.fallback}
+
+```scss
+var.fallback($var) //=> string
+
+/// @param {string} $var - A custom property `var()` string.
+/// @return {string} The fallback value of the `var()` string. May be null if the `var()` does not have a fallback value.
+/// @throw If the value is not a custom property.
+```
+
+Returns the fallback value of a custom property `var()` string. The value
+may be null if the `var()` does not have a fallback value.
+
+```scss
+$var: var(--foo, var(--bar, 8px));
+@debug var.fallback($var); // "var(--bar, 8px)"
+```
+
+### `deep-fallback` {#var.deep-fallback}
+
+```scss
+var.deep-fallback($var) //=> string
+
+/// @param {string} $var - A custom property `var()` string.
+/// @return {string} The deep fallback value of the `var()` string. May be null if the `var()` does not have a fallback value.
+/// @throw If the value is not a custom property.
+```
+
+Returns the deep fallback value of a custom property `var()` string. The
+value may be null if the `var()` does not have a fallback value.
+
+If a fallback value is another `var()`, this function will return the final
+concrete value in the chain.
+
+```scss
+$var: var(--foo, var(--bar, 8px));
+@debug var.deep-fallback($var); // "8px"
+```
+
+### `set-fallback` {#var.set-fallback}
+
+```scss
+var.set-fallback($var, $new-fallback) //=> string
+
+/// @param {string} $var - A custom property `var()` string.
+/// @param {*} $new-fallback - The new fallback value. May be null to remove a value.
+/// @return {string} A custom property `var()` string with the new fallback value.
+/// @throw If the value is not a custom property.
+```
+
+Creates a new custom property `var()` string and returns it with the
+specified new fallback value.
+
+```scss
+$var: var(--foo, var(--bar, 8px));
+$new-var: set-fallback($var, 16px);
+@debug $new-var; // "var(--foo, 16px)"
+```
+
+### `deep-set-fallback` {#var.deep-set-fallback}
+
+```scss
+var.deep-set-fallback($var, $new-fallback) //=> string
+
+/// @param {string} $var - A custom property `var()` string.
+/// @param {*} $new-fallback - The new fallback value. May be null to remove a value.
+/// @return {string} A custom property `var()` string with the new deep fallback value.
+/// @throw If the value is not a custom property.
+```
+
+Creates a new custom property `var()` string and returns it with the
+specified new deep fallback value.
+
+If the provided `var()` string's fallback value is another `var()`, this
+function will set the final fallback value in the chain.
+
+```scss
+$var: var(--foo, var(--bar, 8px));
+$new-var: var.deep-set-fallback($var, 16px);
+@debug $new-var; // "var(--foo, var(--bar, 16px))"
+```
+
+### `is-var` {#var.is-var}
+
+```scss
+var.is-var($var) //=> boolean
+
+/// @param {*} $var - The value to test.
+/// @return {boolean} True if the value is a custom property `var()` string, or false if not.
+```
+
+Indicates whether or not a value is a custom property `var()` string.
+
+```scss
+$var: var(--foo);
+@debug var.is-var($var); // true
+```
diff --git a/package.json b/package.json
index 86648f1fce..577ee434b2 100644
--- a/package.json
+++ b/package.json
@@ -31,6 +31,8 @@
     "build:catalog": "wireit",
     "build:scripts": "wireit",
     "update-docs": "wireit",
+    "update-docs:components": "wireit",
+    "update-docs:sass-ext": "wireit",
     "update-size": "wireit"
   },
   "type": "module",
@@ -169,6 +171,12 @@
       "clean": "if-file-deleted"
     },
     "update-docs": {
+      "dependencies": [
+        "update-docs:components",
+        "update-docs:sass-ext"
+      ]
+    },
+    "update-docs:components": {
       "command": "node scripts/analyzer/update-docs.js",
       "files": [
         "docs/components/*.md",
@@ -184,6 +192,19 @@
         "build:scripts"
       ]
     },
+    "update-docs:sass-ext": {
+      "command": "node scripts/update-sass-ext-docs.js --input=./sass/ext/ --output=./docs/sass/sass-ext.md",
+      "files": [
+        "docs/sass/sass-ext.md",
+        "sass/ext/_*.scss",
+        "!sass/ext/*_test.scss",
+        "scripts/update-sass-ext-docs.js"
+      ],
+      "output": [],
+      "dependencies": [
+        "build:scripts"
+      ]
+    },
     "update-size": {
       "command": "node scripts/size/update-size.js",
       "dependencies": [
diff --git a/sass/ext/_assert.scss b/sass/ext/_assert.scss
index ad19557d8f..c708d243cb 100644
--- a/sass/ext/_assert.scss
+++ b/sass/ext/_assert.scss
@@ -50,8 +50,8 @@
   @return throw.error($message, $source);
 }
 
-/// Asserts that the argument is a specific type. If it is, the argument is
-/// returned, otherwise an error is thrown.
+/// Asserts that the argument is not a specific type. The argument is returned
+/// if it does not match. An error is thrown if the argument matches the type.
 ///
 /// @example scss
 ///   @function get-strict($map, $key) {
diff --git a/sass/ext/_throw.scss b/sass/ext/_throw.scss
index cca14dfcf9..8316cf6127 100644
--- a/sass/ext/_throw.scss
+++ b/sass/ext/_throw.scss
@@ -32,10 +32,10 @@
 ///   @function mix-primary-on-surface($values) {
 ///     $primary: get-value($values, 'primary');
 ///     $surface: get-value($values, 'surface');
-///     $error: throw.get-error($primary, $secondary);
+///     $error: throw.get-error($primary, $surface);
 ///     @if $error {
 ///       // Return early to guard logic against additional errors since
-///       // $primary or $secondary may be a string instead of a color.
+///       // $primary or $surface may be a string instead of a color.
 ///       @return $error;
 ///     }
 ///
diff --git a/sass/ext/_var.scss b/sass/ext/_var.scss
index 52e141a197..7170c06f87 100644
--- a/sass/ext/_var.scss
+++ b/sass/ext/_var.scss
@@ -46,7 +46,7 @@
 ///
 /// @example scss
 ///   $var: var(--foo);
-///   @debug var.name($var); // "foo"
+///   @debug var.name($var); // "--foo"
 ///
 /// @param {string} $var - A custom property `var()` string.
 /// @return {string} The custom property variable name.
diff --git a/scripts/update-sass-ext-docs.ts b/scripts/update-sass-ext-docs.ts
new file mode 100644
index 0000000000..38c523830e
--- /dev/null
+++ b/scripts/update-sass-ext-docs.ts
@@ -0,0 +1,180 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as fs from 'fs';
+import * as path from 'path';
+import * as util from 'util';
+
+/**
+ * A Sassdoc comment block.
+ */
+interface SassdocComment {
+  /**
+   * The content of the Sassdoc comment block, without the forward slashes
+   * (`///`).
+   */
+  content: string;
+  /**
+   * The Sass symbol the comment block is attached to (ex: `@function foo`,
+   * `@mixin bar`, `$baz`).
+   */
+  symbol: string;
+}
+
+/**
+ * A sassdoc file.
+ */
+interface SassdocModule {
+  /**
+   * The Sass file's module name (ex: `foo-ext` for `_foo-ext.scss`).
+   */
+  name: string;
+  /**
+   * The Sassdoc comments in the file.
+   */
+  comments: SassdocComment[];
+}
+
+function parseSassFile(sassFile: string): SassdocModule {
+  const content = fs.readFileSync(sassFile, 'utf-8');
+
+  const comments: SassdocComment[] = [];
+  let sassdocLines: string[] = [];
+  for (const line of content.split('\n')) {
+    if (line.startsWith('///')) {
+      sassdocLines.push(line.replace(/^\/\/\/\s?/, ''));
+      continue;
+    }
+
+    const symbolMatch = line.match(/(?:@function|@mixin)\s*(\$?[\w-]+)/);
+    if (symbolMatch && sassdocLines.length) {
+      const symbol = symbolMatch[1];
+      // Ignore private documented symbols.
+      if (!symbol.startsWith('_')) {
+        comments.push({
+          symbol,
+          content: sassdocLines.join('\n'),
+        });
+      }
+
+      sassdocLines = [];
+      continue;
+    }
+  }
+
+  return {
+    name: path.basename(sassFile).replace(/^_|\.scss$/g, ''),
+    comments,
+  };
+}
+
+const TWO_SPACES = '  ';
+const FOUR_SPACES = '    ';
+
+function sassdocToMarkdown(
+  comment: SassdocComment,
+  moduleName: string,
+): string {
+  const header = `### \`${comment.symbol}\` {#${moduleName}.${comment.symbol}}\n\n`;
+  let markdown = '';
+
+  const lines = comment.content.split('\n');
+  const annotations: string[] = [];
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i];
+
+    const exampleMatch = line.match(/^@example(?:\s-?(\w+))?/);
+    if (exampleMatch) {
+      const exampleLines = [];
+      while (lines[i + 1] === '' || lines[i + 1]?.startsWith(TWO_SPACES)) {
+        exampleLines.push(lines[i + 1].replace(/^\s\s/, ''));
+        i++;
+      }
+
+      const exampleLang = exampleMatch[1] || 'scss';
+      const exampleMarkdown =
+        '```' + `${exampleLang}\n` + exampleLines.join('\n') + '```\n\n';
+      markdown += exampleMarkdown;
+      continue;
+    }
+
+    const annotationMatch = line.match(/^@(\w+)/);
+    if (annotationMatch) {
+      const annotationLines = [line];
+      // Collect multi-line annotation lines.
+      while (lines[i + 1]?.startsWith(FOUR_SPACES)) {
+        annotationLines.push(lines[i + 1].trim());
+        i++;
+      }
+
+      // Annotations are listed at the end of the markdown.
+      annotations.push(annotationLines.join(' '));
+      continue;
+    }
+
+    markdown += `${line}\n`;
+  }
+
+  const params = annotations
+    .filter((annotation) => annotation.startsWith('@param'))
+    .map((annotation) => annotation.match(/(\$[\w-]+)/)?.[1]);
+  const returnType = annotations
+    .find((annotation) => annotation.startsWith('@return'))
+    ?.match(/@return\s{(\w+)}/)?.[1];
+  const returnComment = returnType ? ` //=> ${returnType}` : '';
+  const signature =
+    '```scss\n' +
+    `${moduleName}.${comment.symbol}(${params.join(', ')})${returnComment}` +
+    '\n\n' +
+    annotations.map((a) => `/// ${a}`).join('\n') +
+    '\n```\n\n';
+
+  return header + signature + markdown;
+}
+
+const {values} = util.parseArgs({
+  options: {
+    input: {type: 'string'},
+    output: {type: 'string'},
+  },
+});
+
+if (!values.input || !values.output) {
+  throw new Error(
+    'Usage: update-sass-ext-docs --input=path/to/sass/ext/ --output=path/to/sass-ext.md',
+  );
+}
+
+const outputPath = values.output;
+const sassExtPath = values.input;
+const sassdocModules = fs
+  .readdirSync(sassExtPath)
+  .filter(
+    (file) =>
+      file.startsWith('_') && file.endsWith('.scss') && !file.includes('test'),
+  )
+  .map((file) => parseSassFile(path.join(sassExtPath, file)));
+
+let generatedDocs = ``;
+for (const sassdocModule of sassdocModules) {
+  generatedDocs += `## \`${sassdocModule.name}\`\n\n`;
+  for (const comment of sassdocModule.comments) {
+    generatedDocs += sassdocToMarkdown(comment, sassdocModule.name);
+  }
+}
+
+const mdContent = fs.readFileSync(outputPath, 'utf-8');
+const MARKER = '<!-- generated_docs_start -->\n';
+const newMdContent =
+  mdContent.substring(0, mdContent.indexOf(MARKER)) +
+  MARKER +
+  '\n' +
+  generatedDocs.trim() +
+  '\n';
+
+fs.writeFileSync(outputPath, newMdContent);
+
+console.log('Updated sass-ext.md');