Muse subscription for OpenCode (serverless)

# Muse subscription for OpenCode (serverless)

Route OpenCode's `coder` / `reviewer` agents at your Muse coding
subscription. OpenCode calls `https://api.meta.ai/v1` directly from its own
process — no local server, proxy, or background task.

> **Already have your Muse Code authenticated? Otherwise it does not work.**
> Run `muse login` (device-code OAuth) BEFORE installing. The installer
> reuses that login's subscription key and refuses to continue without it.

## Install

Windows:

```powershell
powershell -NoProfile -ExecutionPolicy Bypass -File .\install.ps1
```

macOS / Linux:

```sh
sh ./install.sh
```

What it does:

1. Refuses unless `muse` is installed and `~/.config/muse/auth.json` holds a
   subscription key.
2. Copies that key into OpenCode's `auth.json` as `muse-sub` (read from disk
   on every launch — no env-var timing issues).
3. Merges a `muse-sub` provider (`muse-spark-1.3`) plus `coder`/`reviewer`
   agent mappings into `opencode.jsonc` (or `.json`), preserving comments.
   A timestamped backup is kept next to the config; a failed merge restores
   it automatically. Existing entries are never overwritten.
4. Verifies against the live Meta API.

Then restart OpenCode. Re-run the installer whenever Muse rotates the key.

## Notes

- Spend is metered to the Muse subscription (the API streams
  `response.subscription_usage` per call).
- Reasoning effort is the API default; per-model effort selection is not
  wired up.
- Uninstall: delete the `muse-sub` block from the provider section, the two
  agent mappings, and the `muse-sub` entry in `auth.json`.