diff --git a/packages/svelte/src/animate/public.d.ts b/packages/svelte/src/animate/public.d.ts
index 8a6cf5ebf6..ded489464b 100644
--- a/packages/svelte/src/animate/public.d.ts
+++ b/packages/svelte/src/animate/public.d.ts
@@ -1,4 +1,4 @@
-// todo: same as Transition, should it be shared?
+/** Configuration returned by animation functions. */
 export interface AnimationConfig {
 	delay?: number;
 	duration?: number;
@@ -7,6 +7,7 @@ export interface AnimationConfig {
 	tick?: (t: number, u: number) => void;
 }
 
+/** Options for the `flip` animation. */
 export interface FlipParams {
 	delay?: number;
 	duration?: number | ((len: number) => number);
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index e3560753b4..5192d86b49 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -85,6 +85,7 @@ const global_constants = {
 	'Math.SQRT1_2': Math.SQRT1_2
 };
 
+/** Represents a variable binding in a component scope. */
 export class Binding {
 	/** @type {Scope} */
 	scope;
@@ -602,6 +603,7 @@ class Evaluation {
 	}
 }
 
+/** Represents a lexical scope in the component, tracking bindings and references. */
 export class Scope {
 	/** @type {ScopeRoot} */
 	root;
@@ -859,6 +861,7 @@ const logical = {
 	'??': (left, right) => left ?? right
 };
 
+/** The root scope of a component, managing all top-level bindings. */
 export class ScopeRoot {
 	/** @type {Set<string>} */
 	conflicts = new Set();
diff --git a/packages/svelte/src/compiler/phases/types.d.ts b/packages/svelte/src/compiler/phases/types.d.ts
index a1a85ce145..e7e331bbbf 100644
--- a/packages/svelte/src/compiler/phases/types.d.ts
+++ b/packages/svelte/src/compiler/phases/types.d.ts
@@ -17,6 +17,7 @@ import type {
 import type { Scope, ScopeRoot } from './scope.js';
 import type { ExpressionMetadata } from './nodes.js';
 
+/** Parsed JavaScript module/script with scope information. */
 export interface Js {
 	ast: Program;
 	scope: Scope;
@@ -24,17 +25,20 @@ export interface Js {
 	has_await: boolean;
 }
 
+/** Parsed template with scope information. */
 export interface Template {
 	ast: AST.Fragment;
 	scope: Scope;
 	scopes: Map<AST.SvelteNode, Scope>;
 }
 
+/** A reactive `$:` statement with its dependencies and assignments. */
 export interface ReactiveStatement {
 	assignments: Set<Binding>;
 	dependencies: Binding[];
 }
 
+/** Metadata for a declaration that contains an await expression. */
 export interface AwaitedDeclaration {
 	id: Identifier;
 	has_await: boolean;
@@ -68,6 +72,7 @@ export interface Analysis {
 	pickled_awaits: Set<AwaitExpression>;
 }
 
+/** Analysis results specific to a Svelte component. */
 export interface ComponentAnalysis extends Analysis {
 	root: ScopeRoot;
 	instance: Js;
diff --git a/packages/svelte/src/compiler/types/css.d.ts b/packages/svelte/src/compiler/types/css.d.ts
index 13eb880d83..e7d5b6b858 100644
--- a/packages/svelte/src/compiler/types/css.d.ts
+++ b/packages/svelte/src/compiler/types/css.d.ts
@@ -1,19 +1,23 @@
 import type { AST } from '#compiler';
 
 export namespace _CSS {
+	/** Base interface for all CSS AST nodes. */
 	export interface BaseNode {
 		start: number;
 		end: number;
 	}
 
+	/** Base interface for CSS stylesheets. */
 	export interface StyleSheetBase extends BaseNode {
 		children: Array<Atrule | Rule>;
 	}
 
+	/** A standalone CSS file stylesheet. */
 	export interface StyleSheetFile extends StyleSheetBase {
 		type: 'StyleSheetFile';
 	}
 
+	/** A `<style>` block from a Svelte component. */
 	export interface StyleSheet extends StyleSheetBase {
 		type: 'StyleSheet';
 		attributes: any[]; // TODO
@@ -26,6 +30,7 @@ export namespace _CSS {
 		};
 	}
 
+	/** A CSS at-rule (e.g. `@media`, `@keyframes`). */
 	export interface Atrule extends BaseNode {
 		type: 'Atrule';
 		name: string;
@@ -33,6 +38,7 @@ export namespace _CSS {
 		block: Block | null;
 	}
 
+	/** A CSS rule with a selector list and a block of declarations. */
 	export interface Rule extends BaseNode {
 		type: 'Rule';
 		prelude: SelectorList;
@@ -109,21 +115,25 @@ export namespace _CSS {
 		};
 	}
 
+	/** A CSS type selector (e.g. `div`, `span`). */
 	export interface TypeSelector extends BaseNode {
 		type: 'TypeSelector';
 		name: string;
 	}
 
+	/** A CSS ID selector (e.g. `#my-id`). */
 	export interface IdSelector extends BaseNode {
 		type: 'IdSelector';
 		name: string;
 	}
 
+	/** A CSS class selector (e.g. `.my-class`). */
 	export interface ClassSelector extends BaseNode {
 		type: 'ClassSelector';
 		name: string;
 	}
 
+	/** A CSS attribute selector (e.g. `[href]`, `[type="text"]`). */
 	export interface AttributeSelector extends BaseNode {
 		type: 'AttributeSelector';
 		name: string;
@@ -132,27 +142,32 @@ export namespace _CSS {
 		flags: string | null;
 	}
 
+	/** A CSS pseudo-element selector (e.g. `::before`, `::after`). */
 	export interface PseudoElementSelector extends BaseNode {
 		type: 'PseudoElementSelector';
 		name: string;
 	}
 
+	/** A CSS pseudo-class selector (e.g. `:hover`, `:nth-child()`). */
 	export interface PseudoClassSelector extends BaseNode {
 		type: 'PseudoClassSelector';
 		name: string;
 		args: SelectorList | null;
 	}
 
+	/** A CSS percentage value (e.g. in `@keyframes`). */
 	export interface Percentage extends BaseNode {
 		type: 'Percentage';
 		value: string;
 	}
 
+	/** A CSS nesting selector (`&`). */
 	export interface NestingSelector extends BaseNode {
 		type: 'NestingSelector';
 		name: '&';
 	}
 
+	/** An `nth` value used in pseudo-class selectors like `:nth-child()`. */
 	export interface Nth extends BaseNode {
 		type: 'Nth';
 		value: string;
@@ -169,23 +184,26 @@ export namespace _CSS {
 		| Nth
 		| NestingSelector;
 
+	/** A CSS combinator (e.g. `>`, `~`, `+`, ` `). */
 	export interface Combinator extends BaseNode {
 		type: 'Combinator';
 		name: string;
 	}
 
+	/** A CSS declaration block (the contents between `{` and `}`). */
 	export interface Block extends BaseNode {
 		type: 'Block';
 		children: Array<Declaration | Rule | Atrule>;
 	}
 
+	/** A CSS property declaration (e.g. `color: red`). */
 	export interface Declaration extends BaseNode {
 		type: 'Declaration';
 		property: string;
 		value: string;
 	}
 
-	// for zimmerframe
+	/** Any CSS AST node. */
 	export type Node =
 		| StyleSheet
 		| Rule
diff --git a/packages/svelte/src/compiler/types/index.d.ts b/packages/svelte/src/compiler/types/index.d.ts
index c04466a24d..22007fc114 100644
--- a/packages/svelte/src/compiler/types/index.d.ts
+++ b/packages/svelte/src/compiler/types/index.d.ts
@@ -49,10 +49,13 @@ export interface CompileResult {
 	ast: any;
 }
 
+/** A compiler warning returned during compilation. */
 export interface Warning extends ICompileDiagnostic {}
 
+/** A compiler error thrown or collected during compilation. */
 export interface CompileError extends ICompileDiagnostic {}
 
+/** Function that returns a CSS class name for scoped styles. */
 export type CssHashGetter = (args: {
 	name: string;
 	filename: string;
@@ -60,6 +63,7 @@ export type CssHashGetter = (args: {
 	hash: (input: string) => string;
 }) => string;
 
+/** Options for optimizing the compiled output. */
 export interface OptimizeOptions {
 	hydrate?: boolean;
 }
@@ -243,10 +247,12 @@ export interface ModuleCompileOptions {
 
 // The following two somewhat scary looking types ensure that certain types are required but can be undefined still
 
+/** Module compile options with all fields required (except rootDir). */
 export type ValidatedModuleCompileOptions = Omit<Required<ModuleCompileOptions>, 'rootDir'> & {
 	rootDir: ModuleCompileOptions['rootDir'];
 };
 
+/** Compile options with all fields validated and required where applicable. */
 export type ValidatedCompileOptions = ValidatedModuleCompileOptions &
 	Omit<
 		Required<CompileOptions>,
@@ -272,6 +278,7 @@ export type ValidatedCompileOptions = ValidatedModuleCompileOptions &
 		hmr: CompileOptions['hmr'];
 	};
 
+/** The kind of a binding in the component scope. */
 export type BindingKind =
 	| 'normal' // A variable that is not in any way special
 	| 'prop' // A normal prop (possibly reassigned or mutated)
@@ -287,6 +294,7 @@ export type BindingKind =
 	| 'template' // A binding declared in the template, e.g. in an `await` block or `const` tag
 	| 'static'; // A binding whose value is known to be static (i.e. each index)
 
+/** The kind of a variable declaration. */
 export type DeclarationKind =
 	| 'var'
 	| 'let'
@@ -302,6 +310,7 @@ export type DeclarationKind =
 	| 'using'
 	| 'await using';
 
+/** Metadata about a state field in a class component. */
 export interface StateField {
 	type: StateCreationRuneName;
 	node: PropertyDefinition | AssignmentExpression;
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index 4d4b6fc21f..de6ac69569 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -28,12 +28,14 @@ import type { ExpressionMetadata } from '../phases/nodes';
 export type Namespace = 'html' | 'svg' | 'mathml';
 
 export namespace AST {
+	/** Base interface for all AST nodes, containing position information. */
 	export interface BaseNode {
 		type: string;
 		start: number;
 		end: number;
 	}
 
+	/** A fragment containing a list of child nodes. */
 	export interface Fragment {
 		type: 'Fragment';
 		nodes: Array<Text | Tag | ElementLike | Block | Comment>;
@@ -74,6 +76,7 @@ export namespace AST {
 		};
 	}
 
+	/** Options provided by `<svelte:options>` in the component. */
 	export interface SvelteOptions {
 		// start/end info (needed for warnings and for our Prettier plugin)
 		start: number;
@@ -325,6 +328,7 @@ export namespace AST {
 		};
 	}
 
+	/** Base interface for all element-like AST nodes. */
 	export interface BaseElement extends BaseNode {
 		name: string;
 		name_loc: SourceLocation;
@@ -332,6 +336,7 @@ export namespace AST {
 		fragment: Fragment;
 	}
 
+	/** A component tag in the template (e.g. `<MyComponent>`). */
 	export interface Component extends BaseElement {
 		type: 'Component';
 		/** @internal */
@@ -346,16 +351,19 @@ export namespace AST {
 		};
 	}
 
+	/** A `<title>` element. */
 	export interface TitleElement extends BaseElement {
 		type: 'TitleElement';
 		name: 'title';
 	}
 
+	/** A `<slot>` element. */
 	export interface SlotElement extends BaseElement {
 		type: 'SlotElement';
 		name: 'slot';
 	}
 
+	/** A standard HTML element (e.g. `<div>`, `<span>`). */
 	export interface RegularElement extends BaseElement {
 		type: 'RegularElement';
 		/** @internal */
@@ -373,11 +381,13 @@ export namespace AST {
 		};
 	}
 
+	/** A `<svelte:body>` element. */
 	export interface SvelteBody extends BaseElement {
 		type: 'SvelteBody';
 		name: 'svelte:body';
 	}
 
+	/** A `<svelte:component>` dynamic component element. */
 	export interface SvelteComponent extends BaseElement {
 		type: 'SvelteComponent';
 		name: 'svelte:component';
@@ -393,11 +403,13 @@ export namespace AST {
 		};
 	}
 
+	/** A `<svelte:document>` element. */
 	export interface SvelteDocument extends BaseElement {
 		type: 'SvelteDocument';
 		name: 'svelte:document';
 	}
 
+	/** A `<svelte:element>` dynamic element. */
 	export interface SvelteElement extends BaseElement {
 		type: 'SvelteElement';
 		name: 'svelte:element';
@@ -420,16 +432,19 @@ export namespace AST {
 		};
 	}
 
+	/** A `<svelte:fragment>` element. */
 	export interface SvelteFragment extends BaseElement {
 		type: 'SvelteFragment';
 		name: 'svelte:fragment';
 	}
 
+	/** A `<svelte:boundary>` element for error boundaries. */
 	export interface SvelteBoundary extends BaseElement {
 		type: 'SvelteBoundary';
 		name: 'svelte:boundary';
 	}
 
+	/** A `<svelte:head>` element. */
 	export interface SvelteHead extends BaseElement {
 		type: 'SvelteHead';
 		name: 'svelte:head';
@@ -441,6 +456,7 @@ export namespace AST {
 		name: 'svelte:options';
 	}
 
+	/** A `<svelte:self>` recursive component element. */
 	export interface SvelteSelf extends BaseElement {
 		type: 'SvelteSelf';
 		name: 'svelte:self';
@@ -454,6 +470,7 @@ export namespace AST {
 		};
 	}
 
+	/** A `<svelte:window>` element. */
 	export interface SvelteWindow extends BaseElement {
 		type: 'SvelteWindow';
 		name: 'svelte:window';
@@ -523,6 +540,7 @@ export namespace AST {
 		};
 	}
 
+	/** A `{#key ...}` block that re-renders when the key expression changes. */
 	export interface KeyBlock extends BaseNode {
 		type: 'KeyBlock';
 		expression: Expression;
@@ -533,6 +551,7 @@ export namespace AST {
 		};
 	}
 
+	/** A `{#snippet ...}` block that defines a reusable template fragment. */
 	export interface SnippetBlock extends BaseNode {
 		type: 'SnippetBlock';
 		expression: Identifier;
@@ -548,11 +567,13 @@ export namespace AST {
 		};
 	}
 
+	/** Base interface for attribute AST nodes. */
 	export interface BaseAttribute extends BaseNode {
 		name: string;
 		name_loc: SourceLocation | null;
 	}
 
+	/** A static or dynamic HTML attribute. */
 	export interface Attribute extends BaseAttribute {
 		type: 'Attribute';
 		/**
@@ -568,6 +589,7 @@ export namespace AST {
 		};
 	}
 
+	/** A spread attribute (e.g. `{...obj}`) on an element. */
 	export interface SpreadAttribute extends BaseNode {
 		type: 'SpreadAttribute';
 		expression: Expression;
@@ -577,6 +599,7 @@ export namespace AST {
 		};
 	}
 
+	/** A `<script>` or `<script module>` block. */
 	export interface Script extends BaseNode {
 		type: 'Script';
 		context: 'default' | 'module';
@@ -584,6 +607,7 @@ export namespace AST {
 		attributes: Attribute[];
 	}
 
+	/** A JavaScript comment found in script blocks or expressions. */
 	export interface JSComment {
 		type: 'Line' | 'Block';
 		value: string;
@@ -595,8 +619,10 @@ export namespace AST {
 		};
 	}
 
+	/** An attribute node or a directive on an element. */
 	export type AttributeLike = Attribute | SpreadAttribute | Directive;
 
+	/** A Svelte directive (e.g. `bind:`, `on:`, `use:`). */
 	export type Directive =
 		| AST.AnimateDirective
 		| AST.BindDirective
@@ -607,6 +633,7 @@ export namespace AST {
 		| AST.TransitionDirective
 		| AST.UseDirective;
 
+	/** A template block (e.g. `{#each}`, `{#if}`, `{#await}`). */
 	export type Block =
 		| AST.EachBlock
 		| AST.IfBlock
@@ -614,6 +641,7 @@ export namespace AST {
 		| AST.KeyBlock
 		| AST.SnippetBlock;
 
+	/** Any element-like AST node (components, regular elements, svelte elements). */
 	export type ElementLike =
 		| AST.Component
 		| AST.TitleElement
@@ -631,6 +659,7 @@ export namespace AST {
 		| AST.SvelteWindow
 		| AST.SvelteBoundary;
 
+	/** A template tag (e.g. `{@render}`, `{@html}`, `{@const}`). */
 	export type Tag =
 		| AST.AttachTag
 		| AST.ConstTag
@@ -640,6 +669,7 @@ export namespace AST {
 		| AST.HtmlTag
 		| AST.RenderTag;
 
+	/** Any node that can appear in the template AST. */
 	export type TemplateNode =
 		| AST.Root
 		| AST.Text
@@ -652,6 +682,7 @@ export namespace AST {
 		| AST.Comment
 		| Block;
 
+	/** Any node in the Svelte AST, including ESTree nodes, template nodes, CSS nodes, and scripts. */
 	export type SvelteNode = Node | TemplateNode | AST.Fragment | _CSS.Node | Script;
 
 	export type { _CSS as CSS };
diff --git a/packages/svelte/src/index.d.ts b/packages/svelte/src/index.d.ts
index 7823c8e33e..006415ebc9 100644
--- a/packages/svelte/src/index.d.ts
+++ b/packages/svelte/src/index.d.ts
@@ -300,6 +300,7 @@ interface DispatchOptions {
 	cancelable?: boolean;
 }
 
+/** A strongly-typed event dispatcher for dispatching custom events. */
 export interface EventDispatcher<EventMap extends Record<string, any>> {
 	// Implementation notes:
 	// - undefined extends X instead of X extends undefined makes this work better with both strict and nonstrict mode
diff --git a/packages/svelte/src/motion/private.d.ts b/packages/svelte/src/motion/private.d.ts
index a6e0f95284..250855ae9c 100644
--- a/packages/svelte/src/motion/private.d.ts
+++ b/packages/svelte/src/motion/private.d.ts
@@ -1,3 +1,4 @@
+/** Internal context passed to spring tick calculations. */
 export interface TickContext {
 	inv_mass: number;
 	dt: number;
diff --git a/packages/svelte/src/motion/public.d.ts b/packages/svelte/src/motion/public.d.ts
index 89145d0383..a7919689de 100644
--- a/packages/svelte/src/motion/public.d.ts
+++ b/packages/svelte/src/motion/public.d.ts
@@ -1,11 +1,13 @@
 import { Readable, type Unsubscriber } from '../store/public.js';
 
+/** Options for configuring spring physics behavior. */
 export interface SpringOptions {
 	stiffness?: number;
 	damping?: number;
 	precision?: number;
 }
 
+/** Options for a single spring update. */
 export interface SpringUpdateOptions {
 	/**
 	 * @deprecated Only use this for the spring store; does nothing when set on the Spring class
@@ -25,8 +27,10 @@ export interface SpringUpdateOptions {
 	preserveMomentum?: number;
 }
 
+/** A function that computes a new value from the target and current value. */
 export type Updater<T> = (target_value: T, value: T) => T;
 
+/** Options for configuring tweened transitions. */
 export interface TweenOptions<T> {
 	delay?: number;
 	duration?: number | ((from: T, to: T) => number);
@@ -38,6 +42,7 @@ export interface TweenOptions<T> {
 // this means both the Spring class and the Spring interface are merged into one with some things only
 // existing on one side. In Svelte 6, remove the type definition and move the jsdoc onto the class in spring.js
 
+/** Legacy spring store interface. Use the `Spring` class for new code. */
 export interface Spring<T> extends Readable<T> {
 	set(new_value: T, opts?: SpringUpdateOptions): Promise<void>;
 	/**
@@ -113,6 +118,7 @@ export class Spring<T> {
 	get current(): T;
 }
 
+/** A store that smoothly transitions between values using tweens. */
 export interface Tweened<T> extends Readable<T> {
 	set(value: T, opts?: TweenOptions<T>): Promise<void>;
 	update(updater: Updater<T>, opts?: TweenOptions<T>): Promise<void>;
diff --git a/packages/svelte/src/transition/public.d.ts b/packages/svelte/src/transition/public.d.ts
index 454840ad79..9b8e3a1916 100644
--- a/packages/svelte/src/transition/public.d.ts
+++ b/packages/svelte/src/transition/public.d.ts
@@ -1,5 +1,7 @@
+/** A function that maps a value between 0 and 1 to an eased value. */
 export type EasingFunction = (t: number) => number;
 
+/** Configuration object returned by transition functions. */
 export interface TransitionConfig {
 	delay?: number;
 	duration?: number;
@@ -8,6 +10,7 @@ export interface TransitionConfig {
 	tick?: (t: number, u: number) => void;
 }
 
+/** Parameters for the `blur` transition. */
 export interface BlurParams {
 	delay?: number;
 	duration?: number;
@@ -16,12 +19,14 @@ export interface BlurParams {
 	opacity?: number;
 }
 
+/** Parameters for the `fade` transition. */
 export interface FadeParams {
 	delay?: number;
 	duration?: number;
 	easing?: EasingFunction;
 }
 
+/** Parameters for the `fly` transition. */
 export interface FlyParams {
 	delay?: number;
 	duration?: number;
@@ -31,6 +36,7 @@ export interface FlyParams {
 	opacity?: number;
 }
 
+/** Parameters for the `slide` transition. */
 export interface SlideParams {
 	delay?: number;
 	duration?: number;
@@ -38,6 +44,7 @@ export interface SlideParams {
 	axis?: 'x' | 'y';
 }
 
+/** Parameters for the `scale` transition. */
 export interface ScaleParams {
 	delay?: number;
 	duration?: number;
@@ -46,6 +53,7 @@ export interface ScaleParams {
 	opacity?: number;
 }
 
+/** Parameters for the `draw` transition (SVG path animation). */
 export interface DrawParams {
 	delay?: number;
 	speed?: number;
@@ -53,6 +61,7 @@ export interface DrawParams {
 	easing?: EasingFunction;
 }
 
+/** Parameters for the `crossfade` transition. */
 export interface CrossfadeParams {
 	delay?: number;
 	duration?: number | ((len: number) => number);