every.channel: sanitized baseline

evolution/proposals/ECP-0052-direct-subscribe-cli.md

@@ -0,0 +1,47 @@
+# ECP-0052: Direct Subscribe CLI (WebRTC Directory Mode)
+
+Status: Draft
+
+## Goal
+
+Allow a non-Tauri node to **subscribe** to a `direct-publish` stream using the same WebRTC data-channel protocol used by the website, so we can:
+
+- validate end-to-end connectivity (publisher -> every.channel bootstrap -> subscriber),
+- capture a short proof artifact (CMAF fragments and/or an `.mp4` remux),
+- debug issues without opening a browser.
+
+## Non-Goals
+
+- This is not MoQ transport.
+- This is not a long-lived relay/mesh node.
+- This does not implement signatures / merkle manifests / anti-junk policy.
+
+## Proposal
+
+Add a new `ec-node direct-subscribe` command that:
+
+1. Locates an offer either:
+   - from `--offer` (an `every.channel://direct?c=...` link), or
+   - from `--directory-url` + `--stream-id` (fetch `/api/directory`, find matching `stream_id`).
+2. Creates a WebRTC *answerer* connection using `just-webrtc` (`SimpleRemotePeerConnection`).
+3. If operating via directory:
+   - POSTs the answer to `/api/answer` with `{ stream_id, answer }`.
+4. Receives object frames on the data channel, decodes via `ec-moq::decode_object_frame`,
+   and writes CMAF artifacts to disk:
+   - `cmaf/init.mp4`
+   - `cmaf/segment_000000.m4s` ... `cmaf/segment_XXXXXX.m4s`
+   - `cmaf/index.m3u8` (VOD playlist, `#EXT-X-ENDLIST`)
+5. Optionally remuxes the captured playlist to an `.mp4` using `ffmpeg -c copy`.
+
+## Why Now
+
+We need a reproducible harness to verify:
+
+- a remote publisher (e.g. a node near an HDHomeRun) can be watched from a distant network,
+- directory announcement/answer flow works without manual copy/paste,
+- received CMAF fragments are valid enough to remux and play.
+
+## Rollout / Reversibility
+
+- Additive CLI only; no protocol changes.
+- Can be removed without affecting existing publish/web paths.