`, favicon, and body of `Root()` to\nmatch your app's existing `index.html`, and stamp anything else your shell\nreferences directly (images, css) with `immutableFileUrl()`.\n\n1. Create `frontend/root.tsx`:\n\n```tsx\n/** @jsxImportSource npm:hono@4/jsx */\nimport { raw } from \"npm:hono@4/html\";\nimport { immutableFileUrl } from \"https://esm.town/v/std/utils/index.ts\";\n\n// The HTML shell for the app. It is never cached, so immutableFileUrl can stamp\n// the current val version into each asset URL — the browser caches those\n// immutably, and publishing the val changes the URLs, refetching exactly once.\nexport function Root() {\n return (\n <>\n {raw(\"<!DOCTYPE html>\")}\n <html lang=\"en\">\n <head>\n <meta charSet=\"UTF-8\" />\n <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\" />\n <title>React Hono Val Town Starter

[{"_1":2,"_3":-5,"_4":-5},"loaderData",{"_5":6,"_7":8,"_9":10},"actionData","errors","root",{"_249":250,"_251":252},"routes/_app.x.$handle.$name",{"_99":98,"_32":44,"_107":89,"_27":108,"_13":14,"_109":-5,"_11":110,"_111":112,"_113":114,"_115":116,"_117":118,"_20":-5,"_119":-5,"_120":-5,"_121":25,"_122":123,"_124":58,"_125":-5,"_126":-5,"_127":128},"routes/_app.x.$handle.$name.branch.$branch.version.$version.diff",{"_11":12,"_13":14,"_15":16,"_17":-5,"_18":-5},"project",{"_42":43,"_32":44,"_37":45,"_46":-5,"_47":25,"_48":49,"_50":49,"_51":52,"_53":-5,"_18":54,"_55":56,"_57":58,"_59":-5,"_60":-5,"_61":62,"_63":64,"_65":66,"_67":68,"_69":70,"_71":-5,"_72":73,"_74":73,"_75":76,"_77":76,"_78":76,"_79":73,"_80":73,"_81":82,"_83":84,"_85":86,"_87":25},"version",5,"changes",[19],"aiChatInfo","userId",{"_20":21,"_22":23,"_24":25,"_26":25,"_27":28,"_29":28},"file",{"_30":31,"_32":28,"_33":20,"_34":36,"_37":38,"_39":14,"_40":41,"_24":25},"previous",{"_30":31,"_32":28,"_33":20,"_34":35},"deleted",false,"deletedHere","path","README.md","latestPath","fileId","01a0495a-b924-761c-aebd-2ee61846be65","name","fileType","content","# React + Hono Starter\n\nA minimal starter template for building client-side React apps with a Hono\nbackend on Val Town. Click **Remix** to get your own copy.\n\n## Picking a starter\n\n| Starter | When to pick it |\n| --- | --- |\n| [`basic-html-starter`](https://www.val.town/x/templates/basic-html-starter) | Static HTML pages. Sprinkle of vanilla JS. No server-side rendering. |\n| [`hono-jsx-starter`](https://www.val.town/x/templates/hono-jsx-starter) | Dynamic server-rendered HTML with JSX. API routes. No React, no SPA. |\n| **[`react-hono-starter`](https://www.val.town/x/templates/react-hono-starter)** *(you're here)* | Client-side React SPA with a Hono API backend. |\n\n**Want to build UI?** Start writing React components in\n[`frontend/components/`](/frontend/components/). Import them into `App.tsx` and\nyou're good to go. Styling is [Twind](https://twind.style/) — just use Tailwind\nutility classes, zero config.\n\n**Want to add an API?** Add routes in [`index.ts`](/index.ts) (there's a\ncommented-out example). Fetch them from your React components.\n\n## Architecture\n\n```mermaid\ngraph LR\n Browser -->|\"GET /\"| Hono[\"index.ts
(Hono server)\"]\n Hono -->|serves| HTML[\"root.tsx\"]\n HTML -->|loads| Entry[\"index.tsx\"]\n Entry -->|renders| App[\"App.tsx\"]\n App -->|renders| Counter[\"Counter.tsx\"]\n```\n\n## File structure\n\n```\nindex.ts ← Hono backend (serves frontend + API routes)\nfrontend/\n root.tsx ← HTML shell (stamps immutable asset URLs)\n index.tsx ← React entrypoint (mounts )\n favicon.svg ← App icon\n components/\n App.tsx ← Root component (layout + view source link)\n Counter.tsx ← Example component with state\n```\n\n## How it works\n\n1. **`index.ts`** is the HTTP entrypoint — a Hono server that serves the\n frontend and any API routes you add.\n2. **`frontend/root.tsx`** is the HTML shell — it loads Twind and stamps\n immutable asset URLs for the favicon and React entrypoint.\n3. **`frontend/index.tsx`** mounts the React app.\n4. **`frontend/components/App.tsx`** is the root layout — add new components\n alongside it.\n5. **`frontend/components/Counter.tsx`** is an example stateful component —\n replace it with your own!\n\n## Next steps\n\n- Add API routes in `index.ts`\n- Add new components in `frontend/components/`\n- Add a SQLite database — see the\n [React Hono Example](https://www.val.town/x/stevekrouse/reactHonoExample) for\n a full-stack example with database, queries, and shared types\n\nTemplate updates and upgrade paths for existing remixes: [CHANGELOG.md](/CHANGELOG.md)\n","# Roverwatch Vision Lab\n\nA standalone, deterministic test harness for evaluating computer-vision systems through a browser window or OBS Browser Source. It is intentionally independent from Roverwatch production code.\n\n## Run and modes\n\nOpen the val endpoint for **Control Mode**. Use **Open Test Screen** to launch the clean display at \\`/test\\`. Control changes are posted to a tiny shared state endpoint, and the Test Screen polls it, so Chrome and OBS stay synchronized even though they use separate browser profiles.\n\n## OBS Browser Source\n\n1. Add a Browser Source in OBS.\n2. Use the URL shown by **Copy OBS URL** (the app's \\`/test\\` URL).\n3. Set width to **1920** and height to **1080**.\n4. Leave custom CSS empty.\n5. Keep “Shutdown source when not visible” disabled if you want uninterrupted sequences.\n6. Start a preset or sequence in Control Mode; the OBS source updates automatically.\n\n## Scenario representation\n\nA scenario keeps visuals separate from expected output:\n\n\\`\\`\\`ts\n{\n id: \"shape.green-circle\",\n name: \"Green Circle\",\n visualState: { kind: \"shape\", shape: \"circle\", color: \"green\" },\n expectedResult: {\n scenarioType: \"shape\",\n visible: true,\n shape: \"circle\",\n color: \"green\"\n }\n}\n\\`\\`\\`\n\nDefinitions live in \\`frontend/scenarios.ts\\`. Stable IDs are carried into ground truth and exported session events.\n\n## Ground truth\n\nControl Mode derives ground truth only from \\`scenario.expectedResult\\`, never from rendered pixels. It adds scenario ID, name, current step, timestamp, and revision. **Copy Ground Truth** copies the exact JSON. \\`/current.json\\` exposes the current shared state for later evaluation tooling.\n\n## State and persistence\n\nThe currently displayed scenario is stored in val-scoped SQLite because OBS and a normal browser cannot share localStorage. Settings, seed, and session event history are stored in browser localStorage under \\`roverwatch-vision-lab.v1\\`. No login or cloud session database is required.\n\n## Add a scenario\n\nAdd a machine-readable object to \\`presets\\` in \\`frontend/scenarios.ts\\`. Pick an existing renderer kind (\\`shape\\`, \\`text\\`, \\`number\\`, or \\`hud\\`) and provide an explicit \\`expectedResult\\`. New scenario types require one renderer branch in \\`ScenarioStage\\` in \\`frontend/components/App.tsx\\`, then definitions can reuse it without changing control logic.\n\n## Exports\n\n**Export Scenario** downloads one reusable scenario definition. Session recording stores timestamp, scenario ID, step, and expected result; **Export Session** downloads those events with the seed.\n\nExample:\n\n\\`\\`\\`json\n{\n \"sessionId\": \"session-1724864400000\",\n \"startedAt\": \"2026-08-28T17:00:00.000Z\",\n \"seed\": 12345,\n \"events\": [\n {\n \"timestamp\": \"2026-08-28T17:00:03.000Z\",\n \"scenarioId\": \"shape.green-circle\",\n \"step\": 1,\n \"expected\": {\"scenarioType\":\"shape\",\"visible\":true,\"shape\":\"circle\",\"color\":\"green\"}\n }\n ]\n}\n\\`\\`\\`\n\n## Deliberately deferred\n\nThis version does not ingest Roverwatch inference output, score accuracy, create confusion matrices, or capture labeled screenshots. Those fit later beside the stable scenario IDs and \\`/current.json\\` feed. The sequence editor starts with the baseline sequence; arbitrary visual step editing is deferred until the core Twitch/OBS spike is validated.\n","createdAt",["D",1787937181507],"branchVersion","branchId","ec5fed3c-97c0-4273-93d2-1fc6dfd46413","id","546ce605-1508-4081-a1fc-e50474041c15","roverwatch-vision-lab",["D",1787937077281],"deletedAt","legacyEnvVars","privacy","public","httpPrivacy","description","Deterministic computer vision test harness","imageUrl","40e69d1a-3254-4858-920b-7b1449761575","pinnedFileId","01a0495a-b924-761c-aebd-32882f84364c","pinPreview",true,"pinMigrated","screenshotVersion","likeCount",0,"orgId","54bae3d1-8223-41e5-b22d-81eb28a263c7","tursoName","546ce60515084081a1fce50474041c15","tursoHostname","546ce60515084081a1fce50474041c15-val-town.aws-us-east-2.turso.io","tursoMeasuredAt",["D",1789501263826],"pinned","userPerm","r","valPerm","blobPerm","rw","emailPerm","sqlitePerm","projectPerm","telemetryPerm","user",{"_99":98,"_106":102},"org",{"_99":98,"_100":-5,"_101":102,"_18":54,"_103":104,"_105":25},"branch",{"_13":88,"_32":89,"_42":41,"_90":43,"_91":-5,"_92":-5,"_93":-5,"_94":-5,"_95":-5,"_96":44,"_97":98},"isOwned",76,"main","projectId","forkedBranchId","forkedBranchVersion","forkedProjectPrivacy","forkedProjectId","forkedProjectOrgId","projectName","userHandle","pchinjr","handle","displayName","avatar","https://images.clerk.dev/oauth_github/img_2OaSpooJk6yZ5KFqyjtIVA4z3SH.jpeg","tier","free","canRestrictVals","profileImageUrl","branchName","","adoptOrgId",{"_42":43,"_32":44,"_37":244,"_46":-5,"_47":25,"_48":49,"_50":49,"_51":52,"_53":-5,"_18":54,"_55":56,"_57":58,"_59":-5,"_60":-5,"_61":62,"_63":64,"_65":66,"_67":68,"_69":245,"_71":-5,"_72":73,"_74":73,"_75":76,"_77":76,"_78":76,"_79":73,"_80":73,"_81":246,"_83":247,"_85":248,"_87":25},"tree",[169,177,178,179],"files",[169,170,171,172,173,174,175,176,177,178,179],"counts",{"_159":62,"_160":139,"_161":62,"_162":163,"_164":165},"contents",[129,130,131,132],"upstreamProject","upstreamBranch","emptyEnvVars","flags",[],"hasHttpFiles","grants","orgs","customDomains",{},{"_42":153,"_32":154,"_30":155,"_135":-5,"_40":41,"_39":139,"_137":58,"_37":156,"_13":62,"_33":157,"_34":-5,"_24":25,"_142":-5,"_27":158},{"_42":147,"_32":148,"_30":149,"_135":-5,"_40":41,"_39":139,"_137":58,"_37":150,"_13":62,"_33":20,"_34":151,"_24":25,"_142":-5,"_27":152},{"_42":144,"_32":28,"_30":31,"_135":-5,"_40":41,"_39":14,"_137":25,"_37":145,"_13":139,"_33":20,"_34":36,"_24":25,"_142":-5,"_27":146},{"_42":133,"_32":134,"_30":56,"_135":-5,"_40":41,"_39":136,"_137":25,"_37":138,"_13":139,"_33":140,"_34":141,"_24":25,"_142":44,"_27":143},"91e86d72-e553-42fe-9a23-f40004831a62","index.ts","parentId",2,"latest",["D",1787937168458],1,"http","import { parseVal, serveImmutableFile } from \"https://esm.town/v/std/utils/index.ts\";\nimport { sqlite } from \"https://esm.town/v/std/sqlite/main.ts\";\nimport { Hono } from \"npm:hono\";\nimport { Root } from \"./frontend/root.tsx\";\nimport { defaultDifficulty, presets } from \"./frontend/scenarios.ts\";\n\nconst app = new Hono();\nawait sqlite.execute(\\`CREATE TABLE IF NOT EXISTS vision_lab_state (\n id INTEGER PRIMARY KEY CHECK (id = 1),\n payload TEXT NOT NULL,\n revision INTEGER NOT NULL DEFAULT 1,\n updated_at TEXT NOT NULL\n)\\`);\n\nconst initial = {\n scenario: presets[0], difficulty: defaultDifficulty, step: 0,\n startedAt: new Date().toISOString(), revision: 1,\n};\nawait sqlite.execute({\n sql: \"INSERT OR IGNORE INTO vision_lab_state (id,payload,revision,updated_at) VALUES (1,?,?,?)\",\n args: [JSON.stringify(initial), 1, new Date().toISOString()],\n});\n\napp.get(\"/\", (c) => c.html(Root()));\napp.get(\"/test\", (c) => c.html(Root()));\napp.get(\"/__immutable/*\", (c) => serveImmutableFile(c.req.path));\napp.get(\"/source\", (c) => c.redirect(parseVal().links.self.val));\n\nasync function readState() {\n const result = await sqlite.execute(\"SELECT payload, revision, updated_at FROM vision_lab_state WHERE id = 1\");\n const row = result.rows[0] as Record;\n return { ...JSON.parse(String(row.payload)), revision: Number(row.revision), updatedAt: row.updated_at };\n}\n\napp.get(\"/api/state\", async (c) => c.json(await readState()));\napp.get(\"/current.json\", async (c) => c.json(await readState()));\n\napp.post(\"/api/state\", async (c) => {\n const body = await c.req.json();\n if (!body?.scenario?.id || !body?.scenario?.visualState || !body?.scenario?.expectedResult) {\n return c.json({ error: \"Invalid scenario payload\" }, 400);\n }\n const current = await readState();\n const next = { ...body, revision: current.revision + 1, startedAt: body.startedAt || new Date().toISOString() };\n const encoded = JSON.stringify(next);\n if (encoded.length > 100_000) return c.json({ error: \"Payload too large\" }, 413);\n await sqlite.execute({\n sql: \"UPDATE vision_lab_state SET payload=?, revision=?, updated_at=? WHERE id=1\",\n args: [encoded, next.revision, new Date().toISOString()],\n });\n return c.json(next);\n});\n\napp.onError((err) => Promise.reject(err));\nexport default app.fetch;","label",[134],"e704022a-12c5-4030-a995-bc1de4d52943",["D",1787937181507],[28],"e8c03566-51a9-483d-9966-c36948fb0bf3","CHANGELOG.md","01a0495a-b924-761c-aebd-29a0c7fb0190",["D",1787937077281],"# Changelog\n\n## 2026-07-30 — Immutable asset caching\n\nFrontend files are now served at version-addressed URLs\n(`/__immutable/45/frontend/index.tsx`) with\n`Cache-Control: public, max-age=31536000, immutable`, so repeat visits load the\nwhole client graph from the browser cache — roughly 3× faster (~665ms → ~157ms\nmeasured). Publishing your val bumps its version, which changes every URL, so\ncaches invalidate automatically. Old-version URLs return 404 after a publish\n(like Next.js build assets); a reload picks up the new version.\n\nWhat changed in the template:\n\n- `frontend/index.html` → [`frontend/root.tsx`](/frontend/root.tsx): the HTML\n shell is now JSX and stamps asset URLs with `immutableFileUrl()`\n- [`index.ts`](/index.ts): serves `Root()` at `/`, and one\n `app.get(\"/__immutable/*\", (c) => serveImmutableFile(c.req.path))` route\n serves all frontend files\n\n### Upgrading an existing remix\n\nYour copy of this template doesn't update automatically. Two options:\n\n**Minimal (most of the benefit):** point both routes at `serveImmutableFile` —\nyour existing bare URLs redirect into versioned space, the new route serves\nthem, and the whole module graph gets cached (costs one redirect per page view):\n\n```ts\nimport { serveImmutableFile } from \"https://esm.town/v/std/utils/index.ts\";\n\napp.get(\"/__immutable/*\", (c) => serveImmutableFile(c.req.path));\napp.get(\"/frontend/**/*\", (c) => serveImmutableFile(c.req.path)); // was serveFile\n```\n\n**Full upgrade (also removes the redirect):** three self-contained steps —\nno other files needed. Adjust the ``, favicon, and body of `Root()` to\nmatch your app's existing `index.html`, and stamp anything else your shell\nreferences directly (images, css) with `immutableFileUrl()`.\n\n1. Create `frontend/root.tsx`:\n\n```tsx\n/** @jsxImportSource npm:hono@4/jsx */\nimport { raw } from \"npm:hono@4/html\";\nimport { immutableFileUrl } from \"https://esm.town/v/std/utils/index.ts\";\n\n// The HTML shell for the app. It is never cached, so immutableFileUrl can stamp\n// the current val version into each asset URL — the browser caches those\n// immutably, and publishing the val changes the URLs, refetching exactly once.\nexport function Root() {\n return (\n <>\n {raw(\"<!DOCTYPE html>\")}\n <html lang=\"en\">\n <head>\n <meta charSet=\"UTF-8\" />\n <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\" />\n <title>React Hono Val Town Starter\n

Diff · v5