diff --git a/package-lock.json b/package-lock.json
index a1ee8fb..3ebcd10 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,7 +16,7 @@
 				"@playwright/test": "^1.36.1",
 				"@sealcode/file-manager": "^1.0.2",
 				"@sealcode/jdd": "^0.4.5",
-				"@sealcode/sealgen": "^0.15.6",
+				"@sealcode/sealgen": "^0.15.8",
 				"@sealcode/ts-predicates": "^0.6.2",
 				"@types/kill-port": "^2.0.0",
 				"@types/leaflet": "^1.9.8",
@@ -844,9 +844,9 @@
 			"integrity": "sha512-EZI7e8EY8gI1pw2bKdevjl+fBJbcSlpNkCZ8XoEOV3cHakPujiT6M4l775RDkfxJSbLX7jhOBkhgPNDfmCpZbg=="
 		},
 		"node_modules/@sealcode/sealgen": {
-			"version": "0.15.6",
-			"resolved": "https://registry.npmjs.org/@sealcode/sealgen/-/sealgen-0.15.6.tgz",
-			"integrity": "sha512-XVmgGwSjzxQXEscvvHiAT6CTcuIV9c4Klb0pDYqNRtXlvZsoJHbhTsp+1Uua9vQh0NRe6Y+V2airw8eLr+ZZpg==",
+			"version": "0.15.8",
+			"resolved": "https://registry.npmjs.org/@sealcode/sealgen/-/sealgen-0.15.8.tgz",
+			"integrity": "sha512-+1V6xqDuvXs1aD2HuUjKj6UAnZ/HOajzENFv+y71nugs9F64/wT25kJxPeXf35sUIHLT9qU5af8q0XhiaIa4Ug==",
 			"dependencies": {
 				"@koa/router": "^12.0.1",
 				"@sealcode/file-manager": "^1.0.2",
diff --git a/package.json b/package.json
index 2ba121f..3587ab9 100644
--- a/package.json
+++ b/package.json
@@ -30,7 +30,7 @@
 	"tmux-scripts": {
 		"watch": [
 			"npm run typecheck:back -- --watch",
-			"npm run build -- --watch",
+			"npx sealgen build --watch",
 			"npm run typecheck:front -- --watch",
 			"npm run start-watch"
 		]
@@ -44,7 +44,7 @@
 		"@playwright/test": "^1.36.1",
 		"@sealcode/file-manager": "^1.0.2",
 		"@sealcode/jdd": "^0.4.5",
-		"@sealcode/sealgen": "^0.15.6",
+		"@sealcode/sealgen": "^0.15.8",
 		"@sealcode/ts-predicates": "^0.6.2",
 		"@types/kill-port": "^2.0.0",
 		"@types/leaflet": "^1.9.8",
diff --git a/src/back/declarations.d.ts b/src/back/declarations.d.ts
new file mode 100644
index 0000000..24504e1
--- /dev/null
+++ b/src/back/declarations.d.ts
@@ -0,0 +1,7 @@
+import type { BaseContext } from "koa";
+
+declare module "@sealcode/jdd" {
+	export interface JDDContext {
+		ctx: BaseContext;
+	}
+}
diff --git a/src/back/jdd-context.ts b/src/back/jdd-context.ts
index 120abdc..750b338 100644
--- a/src/back/jdd-context.ts
+++ b/src/back/jdd-context.ts
@@ -1,16 +1,20 @@
+import type { BaseContext } from "koa";
 import type { JDDContext } from "@sealcode/jdd";
 import type { FilePointer } from "@sealcode/file-manager";
 import { makeSimpleJDDContext } from "@sealcode/jdd";
 import { TheFileManager } from "./file-manager.js";
 import { imageRouter } from "./image-router.js";
 
-export const jdd_context: JDDContext = {
-	...makeSimpleJDDContext(TheFileManager),
-	render_image: async (image: string | FilePointer | null, args) => {
-		if (!image) {
-			return "";
-		}
-		const file = await TheFileManager.toPointer(image);
-		return imageRouter.image(await file.getPath(), args);
-	},
-};
+export function makeJDDContext(ctx: BaseContext): JDDContext {
+	return {
+		...makeSimpleJDDContext(TheFileManager),
+		render_image: async (image: string | FilePointer | null, args) => {
+			if (!image) {
+				return "";
+			}
+			const file = await TheFileManager.toPointer(image);
+			return imageRouter.image(await file.getPath(), args);
+		},
+		ctx,
+	};
+}
diff --git a/src/back/routes/all-components.page.tsx b/src/back/routes/all-components.page.tsx
index 486acdb..cb93751 100644
--- a/src/back/routes/all-components.page.tsx
+++ b/src/back/routes/all-components.page.tsx
@@ -3,9 +3,9 @@ import { TempstreamJSX } from "tempstream";
 import { Page } from "@sealcode/sealgen";
 import html from "../html.js";
 import { registry } from "../jdd-components/components.js";
-import { jdd_context } from "../jdd-context.js";
 import { render } from "@sealcode/jdd";
 import { shuffle } from "../util.js";
+import { makeJDDContext } from "../jdd-context.js";
 
 export const actionName = "AllComponents";
 
@@ -17,6 +17,7 @@ export default new (class AllComponentsPage extends Page {
 
 	async render(ctx: Context) {
 		const components = registry.getAll();
+		const jdd_context = makeJDDContext(ctx);
 		const document = await Promise.all(
 			shuffle(Object.entries(components)).map(
 				async ([component_name, component]) => {
diff --git a/src/back/routes/component-preview/component-input-image.tsx b/src/back/routes/component-preview/component-input-image.tsx
index 930040c..2212b2e 100644
--- a/src/back/routes/component-preview/component-input-image.tsx
+++ b/src/back/routes/component-preview/component-input-image.tsx
@@ -1,24 +1,28 @@
 import type { Image } from "@sealcode/jdd";
+import type { BaseContext } from "koa";
 import type { StatefulPage } from "@sealcode/sealgen";
 import { TempstreamJSX } from "tempstream";
-import { jdd_context } from "../../jdd-context.js";
 import type { ComponentPreviewState } from "../components.sreact.js";
 import type { ComponentPreviewActions } from "./component-preview-actions.js";
 import { printArgPath } from "./print-arg-path.js";
 import { htmlEscape } from "escape-goat";
 import type { FilePointer } from "@sealcode/file-manager";
+import { makeJDDContext } from "../../jdd-context.js";
 
 export function ComponentInputImage<State extends ComponentPreviewState>({
 	arg_path,
 	arg,
 	value,
+	ctx,
 }: {
 	state: State;
 	arg_path: string[];
 	arg: Image;
 	value: FilePointer | null;
 	page: StatefulPage<ComponentPreviewState, typeof ComponentPreviewActions>;
+	ctx: BaseContext;
 }) {
+	const jdd_context = makeJDDContext(ctx);
 	return (
 		<div style="margin-bottom: 10px">
 			<label
diff --git a/src/back/routes/component-preview/component-input-list.tsx b/src/back/routes/component-preview/component-input-list.tsx
index 4dcc6e3..4a1f647 100644
--- a/src/back/routes/component-preview/component-input-list.tsx
+++ b/src/back/routes/component-preview/component-input-list.tsx
@@ -1,5 +1,6 @@
 import type { ComponentArgument, List } from "@sealcode/jdd";
 import type { StatefulPage } from "@sealcode/sealgen";
+import type { BaseContext } from "koa";
 import { TempstreamJSX } from "tempstream";
 import type { ComponentPreviewState } from "../components.sreact.js";
 import { ComponentInput } from "./component-input.js";
@@ -10,12 +11,14 @@ export async function ComponentInputList<
 	T extends ComponentArgument<unknown>
 >({
 	state,
+	ctx,
 	arg_path,
 	arg,
 	value,
 	page,
 }: {
 	state: State;
+	ctx: BaseContext;
 	arg_path: string[];
 	arg: List<T>;
 	value: T[];
@@ -31,6 +34,7 @@ export async function ComponentInputList<
 				<div style="display: flex">
 					<ComponentInput
 						{...{
+							ctx,
 							state,
 							arg_path: [...arg_path, i.toString()],
 							arg: arg.item_type,
diff --git a/src/back/routes/component-preview/component-input-structured.tsx b/src/back/routes/component-preview/component-input-structured.tsx
index 3d14877..20c3580 100644
--- a/src/back/routes/component-preview/component-input-structured.tsx
+++ b/src/back/routes/component-preview/component-input-structured.tsx
@@ -1,3 +1,4 @@
+import type { BaseContext } from "koa";
 import type { ComponentArgument, Structured } from "@sealcode/jdd";
 import type { StatefulPage } from "@sealcode/sealgen";
 import { TempstreamJSX } from "tempstream";
@@ -9,6 +10,7 @@ export function ComponentInputStructured<
 	T extends Structured<Record<string, ComponentArgument<unknown>>>
 >({
 	state,
+	ctx,
 	arg_path,
 	arg,
 	value,
@@ -16,6 +18,7 @@ export function ComponentInputStructured<
 	page,
 }: {
 	state: ComponentPreviewState;
+	ctx: BaseContext;
 	arg_path: string[];
 	arg: T;
 	value: Record<string, unknown>;
@@ -29,6 +32,7 @@ export function ComponentInputStructured<
 				<div>
 					<ComponentInput
 						{...{
+							ctx,
 							state,
 							arg_path: [...arg_path, arg_name],
 							arg,
diff --git a/src/back/routes/component-preview/component-input-table.tsx b/src/back/routes/component-preview/component-input-table.tsx
index 6f1a99a..1030b73 100644
--- a/src/back/routes/component-preview/component-input-table.tsx
+++ b/src/back/routes/component-preview/component-input-table.tsx
@@ -1,16 +1,17 @@
 import type { Table, TableData } from "@sealcode/jdd";
 import { isTableHeader } from "@sealcode/jdd";
 import type { StatefulPage } from "@sealcode/sealgen";
+import type { BaseContext } from "koa";
 import { TempstreamJSX } from "tempstream";
 import type { ComponentPreviewState } from "../components.sreact.js";
 import { ComponentInput } from "./component-input.js";
 import type { ComponentPreviewActions } from "./component-preview-actions.js";
 
-import delete_column_icon from "./table-delete-column.svg";
-import add_row_below_icon from "./table-add-row-below.svg";
 import add_column_right_icon from "./table-add-column-right.svg";
-import delete_row_icon from "./table-delete-row.svg";
+import add_row_below_icon from "./table-add-row-below.svg";
 import add_column_header_icon from "./table-add-row-header-below.svg";
+import delete_column_icon from "./table-delete-column.svg";
+import delete_row_icon from "./table-delete-row.svg";
 import move_column_right_icon from "./table-move-column-right.svg";
 import move_row_down_icon from "./table-move-row-down.svg";
 
@@ -21,11 +22,13 @@ export async function ComponentInputTable<
 >({
 	state,
 	arg_path,
+	ctx,
 	arg,
 	value,
 	page,
 }: {
 	state: State;
+	ctx: BaseContext;
 	arg_path: string[];
 	arg: Table<CellType, HeaderType>;
 	value: TableData<CellType, HeaderType>;
@@ -119,6 +122,7 @@ export async function ComponentInputTable<
 										<ComponentInput
 											{...{
 												state,
+												ctx,
 												arg_path: [
 													...arg_path,
 													"rows",
@@ -136,6 +140,7 @@ export async function ComponentInputTable<
 										<td>
 											<ComponentInput
 												{...{
+													ctx,
 													state,
 													arg_path: [
 														...arg_path,
diff --git a/src/back/routes/component-preview/component-input.tsx b/src/back/routes/component-preview/component-input.tsx
index af8e1a6..0912dc3 100644
--- a/src/back/routes/component-preview/component-input.tsx
+++ b/src/back/routes/component-preview/component-input.tsx
@@ -1,7 +1,9 @@
-import type { TableData } from "@sealcode/jdd";
+import type { FilePointer } from "@sealcode/file-manager";
+import type { ComponentArgument, TableData } from "@sealcode/jdd";
 import { ComponentArguments, Enum, Image, List, Structured, Table } from "@sealcode/jdd";
-import type { ComponentArgument } from "@sealcode/jdd";
 import type { StatefulPage } from "@sealcode/sealgen";
+import { is, predicates } from "@sealcode/ts-predicates";
+import type { BaseContext } from "koa";
 import { TempstreamJSX } from "tempstream";
 import type { ComponentPreviewState } from "../components.sreact.js";
 import { ComponentInputEnum } from "./component-input-enum.js";
@@ -9,15 +11,14 @@ import { ComponentInputImage } from "./component-input-image.js";
 import { ComponentInputList } from "./component-input-list.js";
 import { ComponentInputStructured } from "./component-input-structured.js";
 import { ComponentInputTable } from "./component-input-table.js";
-import { printArgPath } from "./print-arg-path.js";
 import type { ComponentPreviewActions } from "./component-preview-actions.js";
-import { is, predicates } from "@sealcode/ts-predicates";
-import type { FilePointer } from "@sealcode/file-manager";
+import { printArgPath } from "./print-arg-path.js";
 
 export const actionName = "Components";
 const absoluteUrlPattern = "http(s?)(://)((www.)?)(([^.]+).)?([a-zA-z0-9-_]+)";
 
 export function ComponentInput<State extends ComponentPreviewState, T>({
+	ctx,
 	state,
 	arg_path,
 	arg,
@@ -25,6 +26,7 @@ export function ComponentInput<State extends ComponentPreviewState, T>({
 	page,
 }: {
 	state: State;
+	ctx: BaseContext;
 	arg_path: string[];
 	arg: ComponentArgument<T>;
 	value: T;
@@ -35,7 +37,15 @@ export function ComponentInput<State extends ComponentPreviewState, T>({
 	}
 	if (arg instanceof List) {
 		// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
-		return ComponentInputList({ state, arg_path, arg, value: value as T[], page });
+		return ComponentInputList({
+			ctx,
+			state,
+			arg_path,
+			arg,
+			// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
+			value: value as T[],
+			page,
+		});
 	}
 
 	const argType = arg.getTypeName();
@@ -45,6 +55,7 @@ export function ComponentInput<State extends ComponentPreviewState, T>({
 
 	if (arg instanceof Structured) {
 		return ComponentInputStructured({
+			ctx,
 			state,
 			arg_path,
 			arg,
@@ -67,6 +78,7 @@ export function ComponentInput<State extends ComponentPreviewState, T>({
 
 	if (arg instanceof Image) {
 		return ComponentInputImage({
+			ctx,
 			state,
 			arg_path,
 			arg,
@@ -78,6 +90,7 @@ export function ComponentInput<State extends ComponentPreviewState, T>({
 
 	if (arg instanceof Table) {
 		return ComponentInputTable({
+			ctx,
 			state,
 			arg_path,
 			arg,
diff --git a/src/back/routes/component-preview/component-preview-actions.ts b/src/back/routes/component-preview/component-preview-actions.ts
index d6a4cb7..728d8b8 100644
--- a/src/back/routes/component-preview/component-preview-actions.ts
+++ b/src/back/routes/component-preview/component-preview-actions.ts
@@ -1,9 +1,10 @@
 import type { ComponentArgument, List, Table, TableData } from "@sealcode/jdd";
+import type { BaseContext } from "koa";
 import { isTableData, isTableRegularRow } from "@sealcode/jdd";
 import objectPath from "object-path";
 import { registry } from "../../jdd-components/components.js";
-import { jdd_context } from "../../jdd-context.js";
 import type { ComponentPreviewState } from "../components.sreact.js";
+import { makeJDDContext } from "../../jdd-context.js";
 
 function moveElement<T>(array: Array<T>, fromIndex: number, toIndex: number): Array<T> {
 	const element = array.splice(fromIndex, 1)[0];
@@ -13,6 +14,7 @@ function moveElement<T>(array: Array<T>, fromIndex: number, toIndex: number): Ar
 
 export const ComponentPreviewActions = <const>{
 	add_array_item: async (
+		ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[]
@@ -35,7 +37,7 @@ export const ComponentPreviewActions = <const>{
 		objectPath.insert(
 			component_args,
 			arg_path,
-			await argument.item_type.getExampleValue(jdd_context),
+			await argument.item_type.getExampleValue(makeJDDContext(ctx)),
 			// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
 			((objectPath.get(component_args, arg_path) as unknown[]) || []).length
 		);
@@ -45,6 +47,7 @@ export const ComponentPreviewActions = <const>{
 		};
 	},
 	remove_array_item: (
+		_ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[],
@@ -58,6 +61,7 @@ export const ComponentPreviewActions = <const>{
 		};
 	},
 	change_component: async (
+		ctx: BaseContext,
 		state: ComponentPreviewState,
 		inputs: Record<string, string>
 	) => {
@@ -66,10 +70,12 @@ export const ComponentPreviewActions = <const>{
 		return {
 			...state,
 			component: component_name,
-			component_args: (await component?.getExampleValues(jdd_context)) || {},
+			component_args:
+				(await component?.getExampleValues(makeJDDContext(ctx))) || {},
 		};
 	},
 	randomize_args: async (
+		ctx: BaseContext,
 		state: ComponentPreviewState,
 		inputs: Record<string, string>
 	) => {
@@ -77,16 +83,19 @@ export const ComponentPreviewActions = <const>{
 		const component = registry.get(component_name);
 		return {
 			...state,
-			component_args: (await component?.getExampleValues(jdd_context)) || {},
+			component_args:
+				(await component?.getExampleValues(makeJDDContext(ctx))) || {},
 		};
 	},
 	add_table_row: async (
+		ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[],
 		columns: number,
 		type: "header" | "row" = "row"
 	) => {
+		const jdd_context = makeJDDContext(ctx);
 		const component_args = state.component_args;
 		let row;
 		const component = registry.get(state.component);
@@ -131,10 +140,12 @@ export const ComponentPreviewActions = <const>{
 		return result;
 	},
 	add_table_column: async (
+		ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[]
 	) => {
+		const jdd_context = makeJDDContext(ctx);
 		const component_args = state.component_args;
 		const component = registry.get(state.component);
 		if (!component) {
@@ -170,6 +181,7 @@ export const ComponentPreviewActions = <const>{
 	},
 
 	remove_table_column: (
+		_ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[],
@@ -198,6 +210,7 @@ export const ComponentPreviewActions = <const>{
 		};
 	},
 	remove_table_row: (
+		_ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[],
@@ -212,6 +225,7 @@ export const ComponentPreviewActions = <const>{
 		return result;
 	},
 	move_table_column_right: (
+		_ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[],
@@ -237,6 +251,7 @@ export const ComponentPreviewActions = <const>{
 	},
 
 	move_table_row_down: (
+		_ctx: BaseContext,
 		state: ComponentPreviewState,
 		_: Record<string, string>,
 		arg_path: string[],
@@ -257,7 +272,11 @@ export const ComponentPreviewActions = <const>{
 		return result;
 	},
 
-	change_size: (state: ComponentPreviewState, inputs: Record<string, string>) => {
+	change_size: (
+		_ctx: BaseContext,
+		state: ComponentPreviewState,
+		inputs: Record<string, string>
+	) => {
 		return {
 			...state,
 			...inputs,
diff --git a/src/back/routes/components.sreact.tsx b/src/back/routes/components.sreact.tsx
index 3a55e3f..d987bb1 100644
--- a/src/back/routes/components.sreact.tsx
+++ b/src/back/routes/components.sreact.tsx
@@ -6,7 +6,7 @@ import type { Templatable } from "tempstream";
 import { tempstream, TempstreamJSX } from "tempstream";
 import html, { defaultHead } from "../html.js";
 import { registry } from "../jdd-components/components.js";
-import { jdd_context } from "../jdd-context.js";
+import { makeJDDContext } from "../jdd-context.js";
 import { ComponentInput } from "./component-preview/component-input.js";
 import { ComponentPreviewActions } from "./component-preview/component-preview-actions.js";
 
@@ -24,23 +24,23 @@ export default new (class ComponentsPage extends StatefulPage<
 > {
 	actions = ComponentPreviewActions;
 
-	async getInitialState() {
+	async getInitialState(ctx: BaseContext) {
 		const [component_name, component] = Object.entries(registry.getAll())[0];
 		const initial_state = {
 			component: component_name,
-			component_args: await component.getExampleValues(jdd_context),
+			component_args: await component.getExampleValues(makeJDDContext(ctx)),
 		};
 		return initial_state;
 	}
 
-	async serializeState(_context: BaseContext, state: ComponentPreviewState) {
+	async serializeState(ctx: BaseContext, state: ComponentPreviewState) {
 		const component = registry.get(state.component);
 		const result = JSON.stringify({
 			...state,
 			// eslint-disable-next-line @typescript-eslint/no-unsafe-call
 			component_args: component
 				? await component.convertParsedToStorage(
-						jdd_context,
+						makeJDDContext(ctx),
 						state.component_args
 				  )
 				: {},
@@ -48,7 +48,7 @@ export default new (class ComponentsPage extends StatefulPage<
 		return result;
 	}
 
-	async deserializeState(_context: BaseContext, state_string: string) {
+	async deserializeState(ctx: BaseContext, state_string: string) {
 		// eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
 		const raw = JSON.parse(state_string);
 		// eslint-disable-next-line @typescript-eslint/consistent-type-assertions,  @typescript-eslint/no-unsafe-member-access
@@ -60,7 +60,7 @@ export default new (class ComponentsPage extends StatefulPage<
 			component_args: component
 				? // eslint-disable-next-line @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-unsafe-member-access
 				  await component.convertStorageToParsed(
-						jdd_context,
+						makeJDDContext(ctx),
 						// eslint-disable-next-line @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-unsafe-member-access
 						raw.component_args || {}
 				  )
@@ -94,15 +94,17 @@ export default new (class ComponentsPage extends StatefulPage<
 							args: state.component_args,
 						},
 					],
-					jdd_context
+					makeJDDContext(ctx)
 				)}`
 		);
 	}
 
 	async preprocessOverrides(
+		ctx: BaseContext,
 		state: ComponentPreviewState,
 		overrides: Record<string, unknown>
 	) {
+		const jdd_context = makeJDDContext(ctx);
 		const component_name = state.component;
 		if (!component_name) {
 			throw new Error("Unspecified component name");
@@ -131,6 +133,7 @@ export default new (class ComponentsPage extends StatefulPage<
 	containerSizes = ["320", "600", "800", "1024", "1300", "1920"];
 
 	render(ctx: BaseContext, state: ComponentPreviewState) {
+		const jdd_context = makeJDDContext(ctx);
 		const all_components = registry.getAll();
 		const component =
 			registry.get(state.component) || Object.values(all_components)[0];
@@ -163,6 +166,7 @@ export default new (class ComponentsPage extends StatefulPage<
 								<ComponentInput
 									{...{
 										state,
+										ctx,
 										arg_path: [arg_name],
 										arg,
 										value: