static site frontend for mapped.at
mapped.at
Add val town backend config
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val/backend.test.ts
val/mapped-at-backend/main.test.ts
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val/backend.test.ts
val/mapped-at-backend/main.test.ts
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val/backend.ts
val/mapped-at-backend/main.ts
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val/backend.ts
val/mapped-at-backend/main.ts
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val/mapped-at-backend/.vtignore
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val/mapped-at-backend/.vtignore
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val/mapped-at-backend/AGENTS.md
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val/mapped-at-backend/AGENTS.md
···
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You are an advanced assistant specialized in generating Val Town code.
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## Core Guidelines
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- Ask clarifying questions when requirements are ambiguous
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- Provide complete, functional solutions rather than skeleton implementations
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- Test your logic against edge cases before presenting the final solution
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- Ensure all code follows Val Town's specific platform requirements
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- If a section of code that you're working on is getting too complex, consider refactoring it into subcomponents
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## Code Standards
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- Generate code in TypeScript or TSX
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- Add appropriate TypeScript types and interfaces for all data structures
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- Prefer official SDKs or libraries than writing API calls directly
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- Ask the user to supply API or library documentation if you are at all unsure about it
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- **Never bake in secrets into the code** - always use environment variables
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- Include comments explaining complex logic (avoid commenting obvious operations)
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- Follow modern ES6+ conventions and functional programming practices if possible
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## Types of triggers
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### 1. HTTP Trigger
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- Create web APIs and endpoints
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- Handle HTTP requests and responses
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- Example structure:
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```ts
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export default async function (req: Request) {
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return new Response("Hello World");
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}
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```
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Files that are HTTP triggers have http in their name like `foobar.http.tsx`
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### 2. Cron Triggers
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- Run on a schedule
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- Use cron expressions for timing
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- Example structure:
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```ts
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export default async function () {
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// Scheduled task code
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}
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```
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Files that are Cron triggers have cron in their name like `foobar.cron.tsx`
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### 3. Email Triggers
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- Process incoming emails
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- Handle email-based workflows
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- Example structure:
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```ts
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export default async function (email: Email) {
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// Process email
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}
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```
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Files that are Email triggers have email in their name like `foobar.email.tsx`
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## Val Town Standard Libraries
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Val Town provides several hosted services and utility functions.
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### Blob Storage
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```ts
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import { blob } from "https://esm.town/v/std/blob";
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await blob.setJSON("myKey", { hello: "world" });
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let blobDemo = await blob.getJSON("myKey");
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let appKeys = await blob.list("app_");
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await blob.delete("myKey");
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```
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### SQLite
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```ts
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import { sqlite } from "https://esm.town/v/stevekrouse/sqlite";
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const TABLE_NAME = 'todo_app_users_2';
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// Create table - do this before usage and change table name when modifying schema
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await sqlite.execute(`CREATE TABLE IF NOT EXISTS ${TABLE_NAME} (
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id INTEGER PRIMARY KEY AUTOINCREMENT,
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name TEXT NOT NULL
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)`);
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// Query data
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const result = await sqlite.execute(`SELECT * FROM ${TABLE_NAME} WHERE id = ?`, [1]);
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```
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Note: When changing a SQLite table's schema, change the table's name (e.g., add _2 or _3) to create a fresh table.
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### OpenAI
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```ts
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import { OpenAI } from "https://esm.town/v/std/openai";
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const openai = new OpenAI();
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const completion = await openai.chat.completions.create({
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messages: [
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{ role: "user", content: "Say hello in a creative way" },
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],
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model: "gpt-4o-mini",
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max_tokens: 30,
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});
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```
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### Email
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```ts
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import { email } from "https://esm.town/v/std/email";
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// By default emails the owner of the val
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await email({
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subject: "Hi",
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text: "Hi",
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html: "<h1>Hi</h1>"
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});
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```
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## Val Town Utility Functions
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Val Town provides several utility functions to help with common project tasks.
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### Importing Utilities
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Always import utilities with version pins to avoid breaking changes:
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```ts
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import { parseProject, readFile, serveFile } from "https://esm.town/v/std/utils@85-main/index.ts";
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```
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### Available Utilities
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#### **serveFile** - Serve project files with proper content types
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For example, in Hono:
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```ts
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// serve all files in frontend/ and shared/
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app.get("/frontend/*", c => serveFile(c.req.path, import.meta.url));
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app.get("/shared/*", c => serveFile(c.req.path, import.meta.url));
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```
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#### **readFile** - Read files from within the project:
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```ts
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// Read a file from the project
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const fileContent = await readFile("/frontend/index.html", import.meta.url);
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```
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#### **listFiles** - List all files in the project
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```ts
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const files = await listFiles(import.meta.url);
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```
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#### **parseProject** - Extract information about the current project from import.meta.url
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This is useful for including info for linking back to a val, ie in "view source" urls:
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```ts
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const projectVal = parseProject(import.meta.url);
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console.log(projectVal.username); // Owner of the project
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console.log(projectVal.name); // Project name
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console.log(projectVal.version); // Version number
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console.log(projectVal.branch); // Branch name
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console.log(projectVal.links.self.project); // URL to the project page
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```
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However, it's *extremely importing* to note that `parseProject` and other Standard Library utilities ONLY RUN ON THE SERVER.
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If you need access to this data on the client, run it in the server and pass it to the client by splicing it into the HTML page
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or by making an API request for it.
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## Val Town Platform Specifics
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- **Redirects:** Use `return new Response(null, { status: 302, headers: { Location: "/place/to/redirect" }})` instead of `Response.redirect` which is broken
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- **Images:** Avoid external images or base64 images. Use emojis, unicode symbols, or icon fonts/libraries instead
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- **AI Image:** To inline generate an AI image use: `<img src="https://maxm-imggenurl.web.val.run/the-description-of-your-image" />`
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- **Storage:** DO NOT use the Deno KV module for storage
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- **Browser APIs:** DO NOT use the `alert()`, `prompt()`, or `confirm()` methods
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- **Weather Data:** Use open-meteo for weather data (doesn't require API keys) unless otherwise specified
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- **View Source:** Add a view source link by importing & using `import.meta.url.replace("ems.sh", "val.town)"` (or passing this data to the client) and include `target="_top"` attribute
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- **Error Debugging:** Add `<script src="https://esm.town/v/std/catch"></script>` to HTML to capture client-side errors
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- **Error Handling:** Only use try...catch when there's a clear local resolution; Avoid catches that merely log or return 500s. Let errors bubble up with full context
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- **Environment Variables:** Use `Deno.env.get('keyname')` when you need to, but generally prefer APIs that don't require keys
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- **Imports:** Use `https://esm.sh` for npm and Deno dependencies to ensure compatibility on server and browser
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- **Storage Strategy:** Only use backend storage if explicitly required; prefer simple static client-side sites
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- **React Configuration:** When using React libraries, pin versions with `?deps=react@18.2.0,react-dom@18.2.0` and start the file with `/** @jsxImportSource https://esm.sh/react@18.2.0 */`
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- Ensure all React dependencies and sub-dependencies are pinned to the same version
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- **Styling:** Default to using TailwindCSS via `<script src="https://cdn.twind.style" crossorigin></script>` unless otherwise specified
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## Project Structure and Design Patterns
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### Recommended Directory Structure
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```
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├── backend/
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│ ├── database/
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│ │ ├── migrations.ts # Schema definitions
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│ │ ├── queries.ts # DB query functions
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│ │ └── README.md
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│ └── routes/ # Route modules
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│ ├── [route].ts
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│ └── static.ts # Static file serving
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│ ├── index.ts # Main entry point
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│ └── README.md
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├── frontend/
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│ ├── components/
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│ │ ├── App.tsx
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│ │ └── [Component].tsx
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│ ├── favicon.svg
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│ ├── index.html # Main HTML template
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│ ├── index.tsx # Frontend JS entry point
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│ ├── README.md
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│ └── style.css
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├── README.md
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└── shared/
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├── README.md
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└── utils.ts # Shared types and functions
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```
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### Backend (Hono) Best Practices
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- Hono is the recommended API framework
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- Main entry point should be `backend/index.ts`
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- **Static asset serving:** Use the utility functions to read and serve project files:
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```ts
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import { readFile, serveFile } from "https://esm.town/v/std/utils@85-main/index.ts";
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// serve all files in frontend/ and shared/
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app.get("/frontend/*", c => serveFile(c.req.path, import.meta.url));
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app.get("/shared/*", c => serveFile(c.req.path, import.meta.url));
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// For index.html, often you'll want to bootstrap with initial data
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app.get("/", async c => {
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let html = await readFile("/frontend/index.html", import.meta.url);
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// Inject data to avoid extra round-trips
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const initialData = await fetchInitialData();
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const dataScript = `<script>
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window.__INITIAL_DATA__ = ${JSON.stringify(initialData)};
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</script>`;
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html = html.replace("</head>", `${dataScript}</head>`);
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return c.html(html);
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});
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```
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- Create RESTful API routes for CRUD operations
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- Always include this snippet at the top-level Hono app to re-throwing errors to see full stack traces:
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```ts
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// Unwrap Hono errors to see original error details
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app.onError((err, c) => {
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throw err;
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});
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```
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### Database Patterns
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- Run migrations on startup or comment out for performance
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- Change table names when modifying schemas rather than altering
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- Export clear query functions with proper TypeScript typing
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## Common Gotchas and Solutions
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1. **Environment Limitations:**
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- Val Town runs on Deno in a serverless context, not Node.js
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- Code in `shared/` must work in both frontend and backend environments
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- Cannot use `Deno` keyword in shared code
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- Use `https://esm.sh` for imports that work in both environments
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2. **SQLite Peculiarities:**
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- Limited support for ALTER TABLE operations
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- Create new tables with updated schemas and copy data when needed
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- Always run table creation before querying
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3. **React Configuration:**
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- All React dependencies must be pinned to 18.2.0
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- Always include `@jsxImportSource https://esm.sh/react@18.2.0` at the top of React files
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- Rendering issues often come from mismatched React versions
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4. **File Handling:**
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- Val Town only supports text files, not binary
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- Use the provided utilities to read files across branches and forks
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- For files in the project, use `readFile` helpers
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5. **API Design:**
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- `fetch` handler is the entry point for HTTP vals
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- Run the Hono app with `export default app.fetch // This is the entry point for HTTP vals`
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+29
val/mapped-at-backend/deno.json
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val/mapped-at-backend/deno.json
···
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{
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"$schema": "https://raw.githubusercontent.com/denoland/deno/98f62cee78e85bfc47c62ed703777c6bc8794f1c/cli/schemas/config-file.v1.json",
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"lock": false,
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"compilerOptions": {
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"noImplicitAny": false,
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"strict": true,
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"types": ["https://www.val.town/types/valtown.d.ts"],
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"lib": [
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"dom",
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"dom.iterable",
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"dom.asynciterable",
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"deno.ns",
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"deno.unstable"
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]
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},
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"lint": {
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"include": ["deno:/https/esm.town/**/*"],
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"rules": {
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"exclude": ["no-explicit-any"]
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}
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},
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"node_modules_dir": false,
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"experimental": {
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"unstable-node-globals": true,
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"unstable-temporal": true,
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"unstable-worker-options": true,
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"unstable-sloppy-imports": true
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}
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}