Hi

\"\n});\n```\n\n## Val Town Utility Functions\n\nVal Town provides several utility functions to help with common project tasks.\n\n### Importing Utilities\n\nAlways import utilities with version pins to avoid breaking changes:\n\n```ts\nimport { parseProject, readFile, serveFile } from \"https://esm.town/v/std/utils@85-main/index.ts\";\n```\n\n### Available Utilities\n\n\n#### **serveFile** - Serve project files with proper content types\n\nFor example, in Hono:\n\n```ts\n// serve all files in frontend/ and shared/\napp.get(\"/frontend/*\", c => serveFile(c.req.path, import.meta.url));\napp.get(\"/shared/*\", c => serveFile(c.req.path, import.meta.url));\n```\n\n#### **readFile** - Read files from within the project:\n\n```ts\n// Read a file from the project\nconst fileContent = await readFile(\"/frontend/index.html\", import.meta.url);\n```\n\n#### **listFiles** - List all files in the project\n\n```ts\nconst files = await listFiles(import.meta.url);\n```\n\n#### **parseProject** - Extract information about the current project from import.meta.url\n\nThis is useful for including info for linking back to a val, ie in \"view source\" urls:\n\n```ts\nconst projectVal = parseProject(import.meta.url);\nconsole.log(projectVal.username); // Owner of the project\nconsole.log(projectVal.name); // Project name\nconsole.log(projectVal.version); // Version number\nconsole.log(projectVal.branch); // Branch name\nconsole.log(projectVal.links.self.project); // URL to the project page\n```\n\nHowever, it's *extremely importing* to note that `parseProject` and other Standard Library utilities ONLY RUN ON THE SERVER.\nIf 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\nor by making an API request for it.\n\n## Val Town Platform Specifics\n\n- **Redirects:** Use `return new Response(null, { status: 302, headers: { Location: \"/place/to/redirect\" }})` instead of `Response.redirect` which is broken\n- **Images:** Avoid external images or base64 images. Use emojis, unicode symbols, or icon fonts/libraries instead\n- **AI Image:** To inline generate an AI image use: `

`\n- **Storage:** DO NOT use the Deno KV module for storage\n- **Browser APIs:** DO NOT use the `alert()`, `prompt()`, or `confirm()` methods\n- **Weather Data:** Use open-meteo for weather data (doesn't require API keys) unless otherwise specified\n- **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\n- **Error Debugging:** Add `` to HTML to capture client-side errors\n- **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\n- **Environment Variables:** Use `Deno.env.get('keyname')` when you need to, but generally prefer APIs that don't require keys\n- **Imports:** Use `https://esm.sh` for npm and Deno dependencies to ensure compatibility on server and browser\n- **Storage Strategy:** Only use backend storage if explicitly required; prefer simple static client-side sites\n- **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 */`\n- Ensure all React dependencies and sub-dependencies are pinned to the same version\n- **Styling:** Default to using TailwindCSS via `` unless otherwise specified\n\n## Project Structure and Design Patterns\n\n### Recommended Directory Structure\n```\n├── backend/\n│ ├── database/\n│ │ ├── migrations.ts # Schema definitions\n│ │ ├── queries.ts # DB query functions\n│ │ └── README.md\n│ └── routes/ # Route modules\n│ ├── [route].ts\n│ └── static.ts # Static file serving\n│ ├── index.ts # Main entry point\n│ └── README.md\n├── frontend/\n│ ├── components/\n│ │ ├── App.tsx\n│ │ └── [Component].tsx\n│ ├── favicon.svg\n│ ├── index.html # Main HTML template\n│ ├── index.tsx # Frontend JS entry point\n│ ├── README.md\n│ └── style.css\n├── README.md\n└── shared/\n ├── README.md\n └── utils.ts # Shared types and functions\n```\n\n### Backend (Hono) Best Practices\n\n- Hono is the recommended API framework\n- Main entry point should be `backend/index.ts`\n- **Static asset serving:** Use the utility functions to read and serve project files:\n ```ts\n import { readFile, serveFile } from \"https://esm.town/v/std/utils@85-main/index.ts\";\n \n // serve all files in frontend/ and shared/\n app.get(\"/frontend/*\", c => serveFile(c.req.path, import.meta.url));\n app.get(\"/shared/*\", c => serveFile(c.req.path, import.meta.url));\n \n // For index.html, often you'll want to bootstrap with initial data\n app.get(\"/\", async c => {\n let html = await readFile(\"/frontend/index.html\", import.meta.url);\n \n // Inject data to avoid extra round-trips\n const initialData = await fetchInitialData();\n const dataScript = ``;\n \n html = html.replace(\"\", `${dataScript}`);\n return c.html(html);\n });\n ```\n- Create RESTful API routes for CRUD operations\n- Always include this snippet at the top-level Hono app to re-throwing errors to see full stack traces:\n ```ts\n // Unwrap Hono errors to see original error details\n app.onError((err, c) => {\n throw err;\n });\n ```\n\n### Database Patterns\n- Run migrations on startup or comment out for performance\n- Change table names when modifying schemas rather than altering\n- Export clear query functions with proper TypeScript typing\n\n## Common Gotchas and Solutions\n\n1. **Environment Limitations:** \n - Val Town runs on Deno in a serverless context, not Node.js\n - Code in `shared/` must work in both frontend and backend environments\n - Cannot use `Deno` keyword in shared code\n - Use `https://esm.sh` for imports that work in both environments\n\n2. **SQLite Peculiarities:**\n - Limited support for ALTER TABLE operations\n - Create new tables with updated schemas and copy data when needed\n - Always run table creation before querying\n\n3. **React Configuration:**\n - All React dependencies must be pinned to 18.2.0\n - Always include `@jsxImportSource https://esm.sh/react@18.2.0` at the top of React files\n - Rendering issues often come from mismatched React versions\n\n4. **File Handling:**\n - Val Town only supports text files, not binary\n - Use the provided utilities to read files across branches and forks\n - For files in the project, use `readFile` helpers\n\n5. **API Design:**\n - `fetch` handler is the entry point for HTTP vals\n - Run the Hono app with `export default app.fetch // This is the entry point for HTTP vals`\n\n",[19,60],"cb63cb88-4ca1-11f1-856e-ee650bb23af1",".vtignore","cb63cc46-4ca1-11f1-856e-ee650bb23af1",17,["D",1778439319799],".git\n.vscode\n.cursorrules\n.DS_Store\nnode_modules\nvendor",[19,67],"ca84dae0-4ca1-11f1-a5ff-ee650bb23af1",14,["D",1778439319622],"directory",[19],{"_36":154,"_13":155,"_39":156,"_41":-5,"_43":44,"_45":135,"_47":48,"_49":157,"_17":51,"_52":76,"_53":-5,"_55":56,"_57":-5,"_89":158,"_18":159},{"_36":73,"_13":19,"_39":42,"_41":-5,"_43":44,"_45":74,"_47":48,"_49":139,"_17":51,"_52":76,"_53":-5,"_55":56,"_57":-5,"_89":140,"_18":141},{"_36":112,"_13":113,"_39":114,"_41":-5,"_43":44,"_45":115,"_47":48,"_49":116,"_17":51,"_52":76,"_53":-5,"_55":56,"_57":-5,"_89":117,"_18":118},{"_36":106,"_13":67,"_39":107,"_41":-5,"_43":44,"_45":108,"_47":48,"_49":109,"_17":51,"_52":24,"_53":71,"_55":56,"_57":-5,"_89":110,"_18":111},{"_36":100,"_13":60,"_39":101,"_41":-5,"_43":44,"_45":102,"_47":48,"_49":103,"_17":51,"_52":24,"_53":64,"_55":56,"_57":-5,"_89":104,"_18":105},{"_36":92,"_13":93,"_39":94,"_41":-5,"_43":44,"_45":95,"_47":48,"_49":96,"_17":51,"_52":24,"_53":97,"_55":56,"_57":-5,"_89":98,"_18":99},{"_36":85,"_13":38,"_39":86,"_41":-5,"_43":44,"_45":87,"_47":48,"_49":88,"_17":51,"_52":24,"_53":54,"_55":56,"_57":-5,"_89":90,"_18":91},"87018d72-e423-11f0-996d-42dde27851f2","87018e26-e423-11f0-996d-42dde27851f2",4,["D",1766950168830],"children",[],[38],"87080f08-e423-11f0-8ebd-42dde27851f2","README.md","87080f9e-e423-11f0-8ebd-42dde27851f2",5,["D",1766950168845],"# Horizon Val\n\n🌅 The current sky at your approximate location, rendered as a CSS gradient. Refreshes every minute.\n\n## Endpoints\n\n### `GET /`\nFull HTML page with sky gradient background. Auto-refreshes every 60 seconds using ``.\n\n**Query Parameters:**\n- `lat` (optional): Latitude override\n- `lon` (optional): Longitude override\n\n### `GET /api/gradient`\nJSON API returning just the CSS gradient data. Perfect for integrating the sky gradient into your own website.\n\n**Query Parameters:**\n- `lat` (optional): Latitude override \n- `lon` (optional): Longitude override\n\n**Response:**\n```json\n{\n \"css\": {\n \"background\": \"linear-gradient(to bottom, rgb(135, 206, 235) 0%, ...)\",\n \"themeColor\": \"rgb(135, 206, 235)\",\n \"fallbackColor\": \"rgb(70, 130, 180)\"\n },\n \"sun\": {\n \"altitudeDegrees\": 45.2,\n \"azimuthDegrees\": 180.5\n },\n \"location\": {\n \"latitude\": 30.26,\n \"longitude\": -97.74\n },\n \"generatedAt\": \"2024-01-15T12:00:00.000Z\",\n \"cacheHint\": \"Gradient changes every minute based on sun position\"\n}\n```\n\n## Usage on Your Personal Website\n\nTo use this gradient as your website background, fetch the API and apply the CSS:\n\n```javascript\nasync function updateSkyBackground() {\n // Use your location or a fixed location\n const lat = 30.26; // Your latitude\n const lon = -97.74; // Your longitude\n \n const res = await fetch(`https://YOUR_VAL_URL/api/gradient?lat=${lat}&lon=${lon}`);\n const data = await res.json();\n \n document.body.style.background = data.css.background;\n document.body.style.backgroundColor = data.css.fallbackColor;\n \n // Update theme-color meta tag\n const themeColor = document.querySelector('meta[name=\"theme-color\"]');\n if (themeColor) {\n themeColor.content = data.css.themeColor;\n }\n}\n\n// Update immediately and then every minute\nupdateSkyBackground();\nsetInterval(updateSkyBackground, 60000);\n```\n\n## Attribution\n\n- Physical model and parameter choices from [\"A Scalable and Production Ready Sky and Atmosphere Rendering Technique\"](https://onlinelibrary.wiley.com/doi/10.1111/cgf.14050) (Sébastien Hillaire)\n- Implementation derived from [\"Production Sky Rendering\"](https://www.shadertoy.com/view/slSXRW) (Andrew Helmer, MIT License)\n- Originally created for [HTML Day 2025](https://html.energy/html-day/2025/index.html)\n",[],[93],"870c780e-e423-11f0-9c73-42dde27851f2","870c78d6-e423-11f0-9c73-42dde27851f2",6,["D",1766950168917],[],[60],"87170724-e423-11f0-92c6-42dde27851f2","871707f6-e423-11f0-92c6-42dde27851f2",7,["D",1766950168971],[],[67],"86ee5ce8-e423-11f0-9c73-42dde27851f2","shared","86ee5d9c-e423-11f0-9c73-42dde27851f2",2,["D",1766950168718],[119,120],[113],{"_36":130,"_13":131,"_39":132,"_41":114,"_43":44,"_45":133,"_47":48,"_49":134,"_17":135,"_52":126,"_53":136,"_55":56,"_57":-5,"_89":137,"_18":138},{"_36":121,"_13":122,"_39":123,"_41":114,"_43":44,"_45":124,"_47":48,"_49":125,"_17":51,"_52":126,"_53":127,"_55":56,"_57":-5,"_89":128,"_18":129},"8732b514-e423-11f0-b005-42dde27851f2","utils.ts","8732b5e6-e423-11f0-b005-42dde27851f2",8,["D",1766950168847],"script","/**\n * Vector utilities for atmospheric rendering calculations\n */\n\nexport type Vec3 = [number, number, number];\n\nexport function clamp(x: number, min: number, max: number) {\n return Math.max(min, Math.min(max, x));\n}\n\nexport function dot(v1: Vec3, v2: Vec3) {\n return v1[0] * v2[0] + v1[1] * v2[1] + v1[2] * v2[2];\n}\n\nexport function len(v: Vec3) {\n return Math.hypot(v[0], v[1], v[2]);\n}\n\nexport function norm(v: Vec3): Vec3 {\n const l = len(v) || 1;\n return [v[0] / l, v[1] / l, v[2] / l];\n}\n\nexport function add(v1: Vec3, v2: Vec3): Vec3 {\n return [v1[0] + v2[0], v1[1] + v2[1], v1[2] + v2[2]];\n}\n\nexport function scale(v: Vec3, s: number): Vec3 {\n return [v[0] * s, v[1] * s, v[2] * s];\n}\n\nexport function exp(v: Vec3): Vec3 {\n return [Math.exp(v[0]), Math.exp(v[1]), Math.exp(v[2])];\n}\n",[],[113,122],"547d99dc-4ca5-11f1-8cc5-ee650bb23af1","gradient.ts","87635692-e423-11f0-801a-42dde27851f2",18,["D",1778440839585],1,"/**\n * Atmosphere gradient renderer (single scattering) using CSS linear-gradient\n *\n * Physical model and parameter choices derived from \"A Scalable and Production\n * Ready Sky and Atmosphere Rendering Technique\" (Sébastien Hillaire).\n *\n * Implementation derived from \"Production Sky Rendering\" (Andrew Helmer,\n * MIT License). Source: https://www.shadertoy.com/view/slSXRW\n */\n\nimport { clamp, dot, len, norm, add, scale, exp, type Vec3 } from \"./utils.ts\";\n\nconst PI = Math.PI;\n\n// Coefficients of media components (m^-1)\nconst RAYLEIGH_SCATTER = [5.802e-6, 13.558e-6, 33.1e-6];\nconst MIE_SCATTER = 3.996e-6;\nconst MIE_ABSORB = 4.44e-6;\nconst OZONE_ABSORB = [0.65e-6, 1.881e-6, 0.085e-6];\n\n// Altitude density distribution metrics\nconst RAYLEIGH_SCALE_HEIGHT = 8e3;\nconst MIE_SCALE_HEIGHT = 1.2e3;\n\n// Additional parameters\nconst GROUND_RADIUS = 6_360e3;\nconst TOP_RADIUS = 6_460e3;\nconst SUN_INTENSITY = 1.0;\n\n// Rendering\nconst SAMPLES = 32; // used for gradient stops and integration steps\nconst FOV_DEG = 75;\n\n// Post-processing\nconst EXPOSURE = 25.0;\nconst GAMMA = 2.2;\nconst SUNSET_BIAS_STRENGTH = 0.1;\n\n// ACES tonemapper (Knarkowicz)\nfunction aces(color: Vec3): Vec3 {\n return color.map((c) => {\n const n = c * (2.51 * c + 0.03);\n const d = c * (2.43 * c + 0.59) + 0.14;\n return Math.max(0, Math.min(1, n / d));\n }) as Vec3;\n}\n\n// Enhance sunset hues (i.e., make warmer)\nfunction applySunsetBias([r, g, b]: Vec3): Vec3 {\n // Relative luminance (sRGB)\n const lum = 0.2126 * r + 0.7152 * g + 0.0722 * b;\n // Weight is higher for darker sky (near horizon/twilight), lower midday\n const w = 1.0 / (1.0 + 2.0 * lum);\n const k = SUNSET_BIAS_STRENGTH; // overall strength\n const rb = 1.0 + 0.5 * k * w; // boost red\n const gb = 1.0 - 0.5 * k * w; // suppress green\n const bb = 1.0 + 1.0 * k * w; // boost blue\n return [Math.max(0, r * rb), Math.max(0, g * gb), Math.max(0, b * bb)];\n}\n\nfunction rayleighPhase(angle: number) {\n return (3 * (1 + Math.cos(angle) ** 2)) / (16 * PI);\n}\n\nfunction miePhase(angle: number) {\n const g = 0.8;\n const scale = 3 / (8 * PI);\n const num = (1 - g ** 2) * (1 + Math.cos(angle) ** 2);\n const denom =\n (2 + g ** 2) * (1 + g ** 2 - 2 * g * Math.cos(angle)) ** (3 / 2);\n return (scale * num) / denom;\n}\n\n// From \"5.3.2 Intersecting Ray or Segment Against Sphere\" (Real-Time Collision Detection)\nfunction intersectSphere(p: Vec3, d: Vec3, r: number) {\n // Sphere center is at origin, so M = P - C = P\n const m = p;\n const b = dot(m, d);\n const c = dot(m, m) - r ** 2;\n const discr = b ** 2 - c;\n if (discr < 0)\n // Ray misses sphere\n return null;\n const t = -b - Math.sqrt(discr);\n if (t < 0)\n // Ray inside sphere; Use far discriminant\n return -b + Math.sqrt(discr);\n return t;\n}\n\n// Optical depth approximation\nfunction computeTransmittance(height: number, angle: number) {\n const rayOrigin: Vec3 = [0, GROUND_RADIUS + height, 0];\n const rayDirection: Vec3 = [Math.sin(angle), Math.cos(angle), 0];\n\n const distance = intersectSphere(rayOrigin, rayDirection, TOP_RADIUS);\n if (!distance) return [1, 1, 1];\n\n // March along the ray using a fixed step size\n const segmentLength = distance / SAMPLES;\n let t = 0.5 * segmentLength;\n\n // Accumulate path-integrated densities\n let odRayleigh = 0; // molecules (Rayleigh)\n let odMie = 0; // aerosols (Mie)\n let odOzone = 0; // ozone (absorption only)\n for (let i = 0; i < SAMPLES; i++) {\n // Position along the ray and its altitude above ground\n const pos = add(rayOrigin, scale(rayDirection, t));\n const h = len(pos) - GROUND_RADIUS;\n\n // Exponential falloff with altitude for Rayleigh and Mie densities\n const dR = Math.exp(-h / RAYLEIGH_SCALE_HEIGHT);\n const dM = Math.exp(-h / MIE_SCALE_HEIGHT);\n\n // Integrate (density × path length)\n odRayleigh += dR * segmentLength;\n\n // Simple ozone layer: triangular profile centered at 25 km, width 30 km\n const ozoneDensity = 1.0 - Math.min(Math.abs(h - 25e3) / 15e3, 1.0);\n odOzone += ozoneDensity * segmentLength;\n\n odMie += dM * segmentLength;\n t += segmentLength;\n }\n\n // Convert integrated densities into per-channel optical depth (Beer-Lambert)\n const tauR = [\n RAYLEIGH_SCATTER[0] * odRayleigh,\n RAYLEIGH_SCATTER[1] * odRayleigh,\n RAYLEIGH_SCATTER[2] * odRayleigh,\n ];\n const tauM = [MIE_ABSORB * odMie, MIE_ABSORB * odMie, MIE_ABSORB * odMie];\n const tauO = [\n OZONE_ABSORB[0] * odOzone,\n OZONE_ABSORB[1] * odOzone,\n OZONE_ABSORB[2] * odOzone,\n ];\n\n // Total optical depth: transmittance T = exp(-tau)\n const tau = [\n -(tauR[0] + tauM[0] + tauO[0]),\n -(tauR[1] + tauM[1] + tauO[1]),\n -(tauR[2] + tauM[2] + tauO[2]),\n ];\n return exp(tau as Vec3);\n}\n\n// Render sky at given solar elevation.\n// numStops controls CSS gradient resolution (fewer = smaller payload, same physics quality).\nexport default function renderGradient(\n altitude: number,\n numStops = SAMPLES,\n): [string, Vec3, Vec3, Vec3[]] {\n const cameraPosition: Vec3 = [0, GROUND_RADIUS, 0];\n const sunDirection: Vec3 = norm([Math.cos(altitude), Math.sin(altitude), 0]);\n\n // Projection constant (used to tilt rays upward)\n const focalZ = 1.0 / Math.tan((FOV_DEG * 0.5 * PI) / 180.0);\n\n const stops = [] as Array<{ percent: number; rgb: Vec3 }>;\n for (let i = 0; i < numStops; i++) {\n const s = i / (numStops - 1);\n\n const viewDirection = norm([0, s, focalZ]);\n\n let inscattered: Vec3 = [0, 0, 0];\n\n const tExitTop = intersectSphere(cameraPosition, viewDirection, TOP_RADIUS);\n if (tExitTop !== null && tExitTop > 0) {\n const rayOrigin = cameraPosition.slice() as Vec3;\n\n // Fixed-step integration along the valid path segment\n const segmentLength = tExitTop / SAMPLES;\n let tRay = segmentLength * 0.5;\n\n // Precompute camera-to-space transmittance and the direction polarity\n const rayOriginRadius = len(rayOrigin);\n const isRayPointingDownwardAtStart =\n dot(rayOrigin, viewDirection) / rayOriginRadius < 0.0;\n const startHeight = rayOriginRadius - GROUND_RADIUS;\n const startRayCos = clamp(\n dot(\n [\n rayOrigin[0] / rayOriginRadius,\n rayOrigin[1] / rayOriginRadius,\n rayOrigin[2] / rayOriginRadius,\n ],\n viewDirection,\n ),\n -1,\n 1,\n );\n const startRayAngle = Math.acos(Math.abs(startRayCos));\n const transmittanceCameraToSpace = computeTransmittance(\n startHeight,\n startRayAngle,\n );\n\n for (let j = 0; j < SAMPLES; j++) {\n // Position and local frame\n const samplePos = add(rayOrigin, scale(viewDirection, tRay));\n const sampleRadius = len(samplePos);\n const upUnit: Vec3 = [\n samplePos[0] / sampleRadius,\n samplePos[1] / sampleRadius,\n samplePos[2] / sampleRadius,\n ];\n const sampleHeight = sampleRadius - GROUND_RADIUS;\n\n // Angles for view ray and sun relative to local up\n const viewCos = clamp(dot(upUnit, viewDirection), -1, 1);\n const sunCos = clamp(dot(upUnit, sunDirection), -1, 1);\n const viewAngle = Math.acos(Math.abs(viewCos));\n const sunAngle = Math.acos(sunCos);\n\n // Transmittance camera→sample and sample→space\n const transmittanceToSpace = computeTransmittance(\n sampleHeight,\n viewAngle,\n );\n const transmittanceCameraToSample = [0, 0, 0] as Vec3;\n for (let k = 0; k < 3; k++) {\n transmittanceCameraToSample[k] = isRayPointingDownwardAtStart\n ? transmittanceToSpace[k] / transmittanceCameraToSpace[k]\n : transmittanceCameraToSpace[k] / transmittanceToSpace[k];\n }\n\n // Transmittance from sample toward the sun\n const transmittanceLight = computeTransmittance(sampleHeight, sunAngle);\n\n // Local densities and phase functions\n const opticalDensityRay = Math.exp(\n -sampleHeight / RAYLEIGH_SCALE_HEIGHT,\n );\n const opticalDensityMie = Math.exp(-sampleHeight / MIE_SCALE_HEIGHT);\n const sunViewCos = clamp(dot(sunDirection, viewDirection), -1, 1);\n const sunViewAngle = Math.acos(sunViewCos);\n const phaseR = rayleighPhase(sunViewAngle);\n const phaseM = miePhase(sunViewAngle);\n\n // Single-scattering contribution\n const scatteredRgb = [0, 0, 0] as Vec3;\n for (let k = 0; k < 3; k++) {\n const rayleighTerm = RAYLEIGH_SCATTER[k] * opticalDensityRay * phaseR;\n const mieTerm = MIE_SCATTER * opticalDensityMie * phaseM;\n scatteredRgb[k] = transmittanceLight[k] * (rayleighTerm + mieTerm);\n }\n\n // Accumulate along the ray\n for (let k = 0; k < 3; k++) {\n inscattered[k] +=\n transmittanceCameraToSample[k] * scatteredRgb[k] * segmentLength;\n }\n tRay += segmentLength;\n }\n\n for (let k = 0; k < 3; k++) inscattered[k] *= SUN_INTENSITY;\n }\n\n // Post-process: exposure → gentle sunset bias → ACES tonemap → gamma → 8-bit RGB\n let color = inscattered.slice() as Vec3;\n color = color.map((c) => c * EXPOSURE) as Vec3;\n color = applySunsetBias(color);\n color = aces(color);\n color = color.map((c) => Math.pow(c, 1.0 / GAMMA)) as Vec3;\n const rgb = color.map((c) => Math.round(clamp(c, 0, 1) * 255)) as Vec3;\n\n // 0% at zenith (top), 100% at horizon (bottom)\n const percent = (1 - s) * 100;\n stops.push({ percent, rgb });\n }\n\n // Compose CSS gradient string from the ordered stops\n stops.sort((a, b) => a.percent - b.percent);\n const colorStops = stops\n .map(\n ({ percent, rgb }) =>\n `rgb(${rgb[0]}, ${rgb[1]}, ${rgb[2]}) ${Math.round(percent * 100) / 100\n }%`,\n )\n .join(\", \");\n return [\n `linear-gradient(to bottom, ${colorStops})`,\n stops[0].rgb,\n stops[stops.length - 1].rgb,\n stops.map((s) => s.rgb),\n ];\n}\n",[],[113,131],["D",1778439319622],[142,143,144],[19],{"_36":66,"_13":67,"_39":68,"_41":42,"_43":44,"_45":69,"_47":48,"_49":151,"_17":51,"_52":24,"_53":71,"_55":56,"_57":-5,"_89":152,"_18":153},{"_36":59,"_13":60,"_39":61,"_41":42,"_43":44,"_45":62,"_47":48,"_49":148,"_17":51,"_52":24,"_53":64,"_55":56,"_57":-5,"_89":149,"_18":150},{"_36":37,"_13":38,"_39":40,"_41":42,"_43":44,"_45":46,"_47":48,"_49":145,"_17":51,"_52":24,"_53":54,"_55":56,"_57":-5,"_89":146,"_18":147},["D",1778439319794],[],[19,38],["D",1778439319789],[],[19,60],["D",1778439319799],[],[19,67],"86d69afe-e423-11f0-8ebd-42dde27851f2","backend","86d69b9e-e423-11f0-8ebd-42dde27851f2",["D",1766950168563],[160],[155],{"_36":161,"_13":162,"_39":163,"_41":156,"_43":44,"_45":164,"_47":48,"_49":165,"_17":166,"_52":167,"_53":168,"_55":56,"_57":-5,"_89":169,"_18":170},"584fed2e-4ca7-11f1-8db0-ee650bb23af1","index.http.ts","86fe5e54-e423-11f0-9c73-42dde27851f2",23,["D",1778441704996],9,"http","/**\n * Horizon - The current sky at your approximate location, rendered as a CSS gradient\n * \n * Endpoints:\n * - GET / : Full HTML page with sky gradient background (refreshes every minute)\n * - GET /api/gradient : JSON endpoint returning just the CSS gradient\n * - GET /api/gradient?lat=XX&lon=YY : JSON endpoint with custom coordinates\n * \n * The gradient can be used as a background for your personal website.\n */\n\nimport { Hono } from \"https://esm.sh/hono@4.4.6\";\nimport SunCalc from \"https://esm.sh/suncalc@1.9.0\";\nimport renderGradient from \"../shared/gradient.ts\";\nimport { parseProject } from \"https://esm.town/v/std/utils@85-main/index.ts\";\n\nconst app = new Hono();\n\n// Unwrap Hono errors to see original error details\napp.onError((err, c) => {\n throw err;\n});\n\n// Helper to get location from Cloudflare headers (Val Town provides these)\nfunction getLocationFromRequest(req: Request): { latitude: number; longitude: number; source: string } {\n // Try various Cloudflare header formats\n let lat = req.headers.get(\"cf-iplatitude\");\n let lon = req.headers.get(\"cf-iplongitude\");\n\n if (lat && lon) {\n return { latitude: parseFloat(lat), longitude: parseFloat(lon), source: \"cf-ip\" };\n }\n\n // Try X-prefixed versions\n lat = req.headers.get(\"x-cf-iplatitude\");\n lon = req.headers.get(\"x-cf-iplongitude\");\n\n if (lat && lon) {\n return { latitude: parseFloat(lat), longitude: parseFloat(lon), source: \"x-cf-ip\" };\n }\n\n // Fallback to a default location\n return { latitude: 0, longitude: 0, source: \"default\" };\n}\n\n// Generate gradient data for a given location\nfunction generateSkyGradient(latitude: number, longitude: number) {\n const now = new Date();\n const sunPos = SunCalc.getPosition(now, latitude, longitude);\n const [gradient, topVec, bottomVec] = renderGradient(sunPos.altitude);\n\n const topColor = `rgb(${topVec[0]}, ${topVec[1]}, ${topVec[2]})`;\n const bottomColor = `rgb(${bottomVec[0]}, ${bottomVec[1]}, ${bottomVec[2]})`;\n\n return {\n gradient,\n topColor,\n bottomColor,\n sunAltitude: sunPos.altitude,\n sunAzimuth: sunPos.azimuth,\n generatedAt: now.toISOString(),\n location: { latitude, longitude },\n };\n}\n\n// Main HTML page - full sky gradient with auto-refresh\napp.get(\"/\", (c) => {\n const url = new URL(c.req.url);\n\n // Allow lat/lon query params to override geo-detection\n const latParam = url.searchParams.get(\"lat\");\n const lonParam = url.searchParams.get(\"lon\");\n\n let latitude: number, longitude: number;\n let hasExplicitLocation = false;\n\n if (latParam && lonParam) {\n latitude = parseFloat(latParam);\n longitude = parseFloat(lonParam);\n hasExplicitLocation = true;\n } else {\n const loc = getLocationFromRequest(c.req.raw);\n latitude = loc.latitude;\n longitude = loc.longitude;\n hasExplicitLocation = loc.source !== \"default\";\n }\n\n const sky = generateSkyGradient(latitude, longitude);\n const projectVal = parseProject(import.meta.url);\n const sourceUrl = projectVal?.links?.self?.project || import.meta.url.replace(\"esm.sh\", \"val.town\");\n\n // If no location detected, show page with JS geolocation prompt\n const geoScript = !hasExplicitLocation ? `\n \n ` : \"\";\n\n const locationStatus = !hasExplicitLocation\n ? \"📍 Detecting location... (using default: 0.00, 0.00)\"\n : `📍 ${latitude.toFixed(2)}, ${longitude.toFixed(2)}`;\n\n const refreshMeta = hasExplicitLocation\n ? ''\n : '';\n\n const html = `\n\n\n \n \n ${refreshMeta}\n \n \n \n Horizon at ${latitude.toFixed(2)}, ${longitude.toFixed(2)}\n \n ${geoScript}\n \n\n\n

${locationStatus} • ☀️ Altitude: ${(sky.sunAltitude * 180 / Math.PI).toFixed(1)}°

Top: ${sky.topColor} | Bottom: ${sky.bottomColor}

View Source • API

\n\n`;\n\n return c.html(html);\n});\n\n// JSON API - returns gradient CSS and colors\napp.get(\"/api/gradient\", (c) => {\n const url = new URL(c.req.url);\n\n const latParam = url.searchParams.get(\"lat\");\n const lonParam = url.searchParams.get(\"lon\");\n\n let latitude: number, longitude: number;\n\n if (latParam && lonParam) {\n latitude = parseFloat(latParam);\n longitude = parseFloat(lonParam);\n } else {\n const loc = getLocationFromRequest(c.req.raw);\n latitude = loc.latitude;\n longitude = loc.longitude;\n }\n\n const sky = generateSkyGradient(latitude, longitude);\n\n return c.json({\n css: {\n background: sky.gradient,\n themeColor: sky.topColor,\n fallbackColor: sky.bottomColor,\n },\n sun: {\n altitudeDegrees: sky.sunAltitude * 180 / Math.PI,\n azimuthDegrees: sky.sunAzimuth * 180 / Math.PI,\n },\n location: sky.location,\n generatedAt: sky.generatedAt,\n cacheHint: \"Gradient changes every minute based on sun position\",\n }, {\n headers: {\n \"Access-Control-Allow-Origin\": \"*\",\n \"Cache-Control\": \"public, max-age=60\",\n },\n });\n});\n\n// Gradient experiment page — 24-hour scrubber to explore how the sky changes\napp.get(\"/experiment\", (c) => {\n const url = new URL(c.req.url);\n\n const latParam = url.searchParams.get(\"lat\");\n const lonParam = url.searchParams.get(\"lon\");\n const tzParam = url.searchParams.get(\"tz\"); // minutes WEST of UTC (browser getTimezoneOffset())\n\n let latitude: number, longitude: number, hasExplicitLocation: boolean;\n\n if (latParam && lonParam) {\n latitude = parseFloat(latParam);\n longitude = parseFloat(lonParam);\n hasExplicitLocation = true;\n } else {\n const loc = getLocationFromRequest(c.req.raw);\n latitude = loc.latitude;\n longitude = loc.longitude;\n hasExplicitLocation = loc.source !== \"default\";\n }\n\n // tz offset in minutes west of UTC; fall back to 0 (UTC) until browser redirects with it\n const tzOffsetMin = tzParam !== null ? parseInt(tzParam) : 0;\n const hasTz = tzParam !== null;\n\n // 1 step per minute — full day at minute granularity\n const TOTAL_STEPS = 24 * 60; // 1440\n // Fewer gradient stops per snapshot keeps the embedded payload small (~130 KB)\n // while the atmospheric integration quality (SAMPLES in gradient.ts) stays the same.\n const EXP_STOPS = 10;\n\n const now = new Date();\n // Anchor index 0 to the user's local midnight, not UTC midnight.\n // nowLocalMins = minutes elapsed since the user's local midnight right now.\n const nowUTCMins = now.getUTCHours() * 60 + now.getUTCMinutes();\n const nowLocalMins = ((nowUTCMins - tzOffsetMin) % 1440 + 1440) % 1440;\n const localMidnightUTC = new Date(now.getTime() - nowLocalMins * 60 * 1000 - now.getUTCSeconds() * 1000 - now.getUTCMilliseconds());\n\n // skyData[minuteIndex] = array of EXP_STOPS RGB triples — built into CSS client-side\n const skyData: number[][][] = [];\n const horizonColors: string[] = [];\n\n for (let i = 0; i < TOTAL_STEPS; i++) {\n const time = new Date(localMidnightUTC.getTime() + i * 60 * 1000);\n const sunPos = SunCalc.getPosition(time, latitude, longitude);\n const [, , bottomVec, stopColors] = renderGradient(sunPos.altitude, EXP_STOPS);\n skyData.push(stopColors as number[][]);\n horizonColors.push(`rgb(${bottomVec[0]},${bottomVec[1]},${bottomVec[2]})`);\n }\n\n // Subsample to every 15 min for the track gradient (96 stops is plenty for visuals)\n const trackSampled = horizonColors.filter((_, i) => i % 15 === 0);\n const trackGradient = `linear-gradient(to right, ${\n trackSampled.map((c, i) => `${c} ${((i / (trackSampled.length - 1)) * 100).toFixed(1)}%`).join(\", \")\n })`;\n\n // Redirect whenever location or timezone is unknown so the client can supply them.\n // tz is always sourced from the browser (server can't know the visitor's timezone).\n const needsRedirect = !hasExplicitLocation || !hasTz;\n const geoRedirectScript = needsRedirect ? `\n const _tz = new Date().getTimezoneOffset();\n ${hasExplicitLocation ? `\n // Already have location — just append tz\n const _u = new URL(window.location.href);\n _u.searchParams.set('tz', _tz);\n window.location.replace(_u.toString());\n ` : `\n if (navigator.geolocation) {\n navigator.geolocation.getCurrentPosition(\n pos => {\n const _lat = pos.coords.latitude.toFixed(4);\n const _lon = pos.coords.longitude.toFixed(4);\n window.location.replace('/experiment?lat=' + _lat + '&lon=' + _lon + '&tz=' + _tz);\n },\n () => { window.location.replace('/experiment?lat=0&lon=0&tz=' + _tz); },\n { timeout: 5000, maximumAge: 300000 }\n );\n } else {\n window.location.replace('/experiment?lat=0&lon=0&tz=' + _tz);\n }\n `}\n ` : \"\";\n\n const html = `\n\n\n \n \n \n Horizon · Gradient Lab\n \n \n\n\n

\n\n

\n \n ${latitude.toFixed(2)}°, ${longitude.toFixed(2)}°\n

\n 12 AM\n 3 AM\n 6 AM\n 9 AM\n 12 PM\n 3 PM\n 6 PM\n 9 PM\n 12 AM\n

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