# Spec: fix-register-guards

## Problem
`scripts/register-guards.sh` has three compounding bugs that prevent the OpenCode guard from ever being registered:

1. **Line 23**: Only checks for `opencode.jsonc`, not `opencode.json`. Most users have `opencode.json` (the default), so the guard is never detected.
2. **Line 34**: Writes to `cfg.setdefault('plugins', [])` (plural `plugins`), but the OpenCode config uses `plugin` (singular). The guard path is added to a key that OpenCode ignores.
3. **Line 33**: Uses `json.load()` to parse `.jsonc` files, which fails on files with `//` comments.

## Fix
1. Check for both `~/.config/opencode/opencode.json` and `~/.config/opencode/opencode.jsonc` (prefer `.json` if both exist)
2. Write to the `plugin` key (singular): `cfg.setdefault('plugin', []).append(source)` — note: must not overwrite existing entries like `opencode-mem`
3. Strip `//` comments before `json.load()`, or use a JSONC-aware parsing approach

Also update the manual install instructions at line 67 to use `plugin` (singular) instead of `plugins`.

## Acceptance Criteria
- Running `register-guards.sh` on a machine with `opencode.json` (no `.jsonc`) successfully registers the guard
- The guard path is added to the `plugin` key (singular), preserving existing entries
- A `.jsonc` file with `//` comments is parsed without error
- The manual install hint message uses `plugin` (singular)