# ECP-0071: Archive Replay DVR Endpoints

## Context

ECP-0070 added relay archival (`wt-archive`) into CAS objects plus JSONL indexes, but there is no read path for viewers to scrub historical content.

## Decision

Add an archive replay path with these pieces:

- `ec-node wt-archive-serve`: lightweight HTTP server that reads archive JSONL indexes + CAS blobs and serves:
  - `/archive/<broadcast>/master.m3u8`
  - `/archive/<broadcast>/video.m3u8`
  - `/archive/<broadcast>/audio.m3u8`
  - `/archive/<broadcast>/init.mp4`
  - `/archive/<broadcast>/segment/<blake3>.m4s`
  - `/archive/<broadcast>/timeline.json`
- HLS playlists are `EVENT` style and include all retained segments by default, so scrub depth is bounded by retained archive data (effectively "infinite" until eviction).
- Cloudflare Worker proxies `/api/archive/*` to a configurable archive origin (`EC_ARCHIVE_ORIGIN`) so `every.channel` can serve replay from the same site domain.
- Web watcher adds an `Archive DVR` mode that plays `/api/archive/<broadcast>/master.m3u8` with native HLS or `hls.js` fallback.
- NixOS module adds `services.every-channel.ec-node.archive.serve.*` to run replay server alongside archival workers.

## Rationale

- Keeps archival and replay in one binary and one deploy surface.
- Preserves CAS as source of truth; playlists are derived views.
- Uses standard HLS+DVR semantics so browser playback + scrubbing works without custom protocol work in the short term.

## Reversibility

- Disable `archive.serve.enable` and remove worker proxy route to revert to archive-only mode.
- `wt-archive` storage format remains unchanged.