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+# Bitvid — AI Agent Guide (AGENTS.md)
+
+This document tells AI agents how Bitvid works **now** and how to extend it going forward. It focuses on the newly adopted **URL‑first playback with WebTorrent fallback** strategy, minimal code touchpoints, and reliable interop with the Nostr ecosystem.
+
+---
+
+## 1) Mission & Product Direction
+
+**Goal:** Stream videos reliably and cheaply.
+
+* **Primary transport:** a **hosted video URL** (MP4/WebM/HLS/DASH) that plays directly in the browser.
+* **Secondary transport (fallback & cost control):** a **WebTorrent magnet** enhanced with **`ws=` (web seed)** and **`xs=` (.torrent URL)**.
+* **Behavior:** Try `url` first. If it’s missing or unreachable, **fallback to WebTorrent** using the same post’s magnet. If the magnet includes `ws`/`xs`, WebTorrent can bootstrap via HTTP and/or peers.
+* **Nostr interop:** Keep existing kind `30078` events for Bitvid’s app data; optionally **mirror a NIP‑94 kind `1063`** event so other clients can discover the same hosted video URL.
+* **Resilience:** Light link‑health probing to hide/flag dead URLs and avoid broken playback.
+
+---
+
+## 2) High‑Level Architecture
+
+* **Frontend app** (vanilla JS + HTML/CSS)
+
+  * **Upload modal** accepts: Title (required), **URL or Magnet** (at least one required), Thumbnail, Description. Optional fields for **`ws`** and **`xs`** help P2P bootstrap.
+  * **Feed / Cards** render video posts, each carrying both `data-play-url` and `data-play-magnet` attributes.
+  * **Player** uses `playVideoWithFallback({ url, magnet })`: probe `url`; if OK, play via `<video>`; else call `torrentClient.streamVideo(magnet, videoEl)`.
+* **Nostr client**
+
+  * Publishes Bitvid’s **kind `30078`** events with content `{ version, title, url?, magnet?, thumbnail?, description?, mode }`.
+  * Subscribes to Bitvid video events and (optionally) **NIP‑94 `kind 1063`** to interop with external clients.
+* **Optional Upload API** (future): If adding server‑side upload (NIP‑96/98), the client would POST to an uploader, receive an HTTPS URL, then publish events.
+
+---
+
+## 3) Data Contracts
+
+### 3.1 Bitvid app event (kind `30078`)
+
+**Content JSON** (superset; some fields optional):
+
+```json
+{
+  "version": 2,
+  "title": "<string>",
+  "url": "https://cdn.example.com/video.mp4",     // optional but recommended
+  "magnet": "magnet:?xt=urn:btih:...&tr=...",      // optional but recommended
+  "thumbnail": "https://.../thumb.jpg",            // optional
+  "description": "<string>",                       // optional
+  "mode": "live" | "dev"                          // optional
+}
+```
+
+**Validation:**
+
+* `title` **required**; **at least one** of `url` **or** `magnet` **required**.
+* If `magnet` present and uploader supplied `ws` and/or `xs`, append them to the magnet before publish.
+
+### 3.2 NIP‑94 mirror (kind `1063`, optional but encouraged)
+
+**Tags (typical):**
+
+* `["url", "https://cdn.example.com/video.mp4"]`
+* `["m", "video/mp4"]` (or `video/webm`, `application/x-mpegURL`, etc.)
+* `["thumb", "https://.../thumb.jpg"]` (optional)
+* `["alt", "<title or description>"]` (optional)
+* `["size", "<bytes>"]` (optional)
+* `["x", "<sha256-of-file>"]` (optional integrity)
+* `["magnet", "magnet:?xt=...&ws=...&xs=..."]` (optional for P2P aware clients)
+
+> Agents SHOULD keep Bitvid’s 30078 as the source of truth, and publish a **lossless mirror** into 1063 when possible.
+
+---
+
+## 4) UI & UX Flows
+
+### 4.1 Upload Flow (author)
+
+1. Author opens **Upload modal**.
+2. Inputs **Title**, plus **either** Hosted URL **or** Magnet (or both). Optionally adds **Web seed base (ws)** and **.torrent URL (xs)**.
+3. Client **augments magnet** with `ws`/`xs` and publishes a kind `30078` event (and optionally a NIP‑94 `1063`).
+
+### 4.2 Consumption Flow (viewer)
+
+1. Feed renders cards with `data-play-url` + `data-play-magnet`.
+2. On click: `playVideoWithFallback()`
+
+   * `probeUrl(url)` → If reachable, set `<video>.src = url` and play.
+   * Else: `torrentClient.streamVideo(magnet, videoEl)`.
+3. UI hides or badges items whose `probeUrl()` fails consistently (cached temporarily).
+
+---
+
+## 5) Key Client Functions (reference)
+
+### 5.1 `augmentMagnet(raw, ws?, xs?)`
+
+* Accepts a magnet URI and conditionally **appends** `ws` and `xs` query params.
+* Returns the same magnet if not a `magnet:` scheme.
+
+### 5.2 `probeUrl(url)`
+
+* `HEAD` request to check availability; expects `2xx` and (ideally) `Accept-Ranges: bytes`.
+* Fallback small `GET` with `Range: bytes=0-1023` can be used if certain hosts block `HEAD`.
+* Returns boolean `ok`.
+
+### 5.3 `playVideoWithFallback({ url, magnet })`
+
+* Try `playHttp(url)` if `probeUrl(url)` passes.
+* Else try `playViaWebTorrent(magnet)`.
+* Show UI error if neither source available.
+
+### 5.4 `playViaWebTorrent(magnet)`
+
+* Uses existing `torrentClient.streamVideo(magnet, videoEl)` under the hood.
+* Benefits if magnet contains `ws`/`xs` for bootstrap.
+
+---
+
+## 6) Markup Contracts
+
+* **Cards:** add both attributes where applicable:
+
+  * `data-play-url="<encoded URL or empty>"`
+  * `data-play-magnet="<magnet or empty>"`
+* **Click delegate:** look for a closest element bearing either attribute; decode `data-play-url` prior to use.
+
+---
+
+## 7) Server Requirements for Hosted URLs
+
+* **CORS:** allow the app origin (or `*`).
+* **Range requests:** ensure `Accept-Ranges: bytes`.
+* **Correct MIME:** `video/mp4`, `video/webm`, `application/x-mpegURL`, etc.
+* **Optional:** expose `Content-Length` for better UX/progress.
+
+---
+
+## 8) P2P Notes for Agents
+
+* **`ws=` (web seed):** HTTP(S) base path where the file is fetchable; enables WebTorrent to download pieces even with zero peers.
+* **`xs=`:** HTTP(S) URL of the `.torrent` metadata so the client can start promptly without DHT/peer discovery.
+* **Trackers:** Keep WSS trackers for peer discovery; they reduce CDN load when peers exist.
+
+---
+
+## 9) Interop & Extensions
+
+* **Live streams:** future option via HLS URLs (MIME `application/x-mpegURL`). For Nostr live presence, consider **NIP‑53** events alongside VOD 1063 entries.
+* **Adaptive Bitrate + P2P:** if ABR is needed with P2P, consider a segment‑sharing overlay (e.g., p2p segment loaders) rather than WebTorrent.
+* **Uploads (optional):** NIP‑96/NIP‑98 flow to obtain a hosted URL, then publish Bitvid/NIP‑94 events.
+
+---
+
+## 10) Testing Checklist (agents)
+
+* **Form validation:** title present; ensure `(url || magnet)` is true; `ws` and `xs` appended only for magnet.
+* **Probe:** healthy URL returns `ok=true`; dead URL hides/badges card; cache prevents re‑probing every render.
+* **Playback:** URL path plays successfully; disconnect network to force WebTorrent path; verify video plays via magnet.
+* **CORS & Range:** verify no console CORS errors; confirm seeking works.
+* **Events:** verify kind `30078` contains `url` and/or `magnet`; optional 1063 mirror created correctly.
+* **Cards:** both `data-play-url` and `data-play-magnet` present; click handler calls fallback player.
+
+---
+
+## 11) Guardrails & Do/Don’t
+
+**Do**
+
+* Fail soft: when URL fails, fall back to magnet without blocking UI.
+* Prefer standards: URL + NIP‑94 mirror when possible.
+* Degrade gracefully when `ws`/`xs` missing; torrent should still work with peers.
+
+**Don’t**
+
+* Don’t require magnet if URL is provided (and vice versa).
+* Don’t assume CORS/Range are configured—probe and message helpfully.
+* Don’t block the main thread with large HEAD/GETs; keep probes lightweight with timeouts.
+
+---
+
+## 12) Quick Reference (snippets)
+
+**Bitvid content object (30078)**
+
+```js
+const content = {
+  version: 2,
+  title,
+  url,            // optional but preferred
+  magnet,         // optional but preferred
+  thumbnail,      // optional
+  description,    // optional
+  mode            // "live" | "dev"
+};
+```
+
+**Magnet augmentation**
+
+```js
+function augmentMagnet(raw, ws, xs) {
+  if (!raw) return "";
+  const u = new URL(raw);
+  if (u.protocol !== "magnet:") return raw;
+  if (ws) u.searchParams.append("ws", ws);
+  if (xs) u.searchParams.append("xs", xs);
+  return u.toString();
+}
+```
+
+**Playback with fallback**
+
+```js
+async function playVideoWithFallback({ url, magnet }) {
+  if (url && await probeUrl(url)) return playHttp(url);
+  if (magnet) return playViaWebTorrent(magnet);
+  throw new Error("No playable source");
+}
+```
+
+---
+
+## 13) Roadmap Hooks (where to extend)
+
+* **Analytics:** Keep using your existing 30078 analytics/logging. Add fields for `play_source: "url"|"torrent"` to measure cost savings.
+* **Integrity:** Optionally compute SHA‑256 of the hosted file (off‑thread) and publish as NIP‑94 `["x", hash]` tag.
+* **Moderation:** Add a background task to periodically probe and mark dead links; publish a lightweight status event so other Bitvid clients learn from each other.
+
+---
+
+**End of AGENTS.md**