# Doc Review: fix-register-guards

## Summary
Updated 3 documentation files that referenced the old `plugins` key (plural) or only mentioned `.jsonc`.

## Doc Updates Made
1. **contracts/harness-integration.md** (line 107, 113): Changed `"plugins"` → `"plugin"` (singular), added `.json` as alternative to `.jsonc`.
2. **plugins/README.md** (line 14, 18): Changed `"plugins"` → `"plugin"` (singular), added `.json` as alternative.
3. **scripts/register-guards.sh** header comment (line 8): Updated detection comment to mention both `.json` and `.jsonc`.

## Findings
- The `plugins` (plural) → `plugin` (singular) correction is critical — users following the old docs would add a `plugins` key that OpenCode ignores, resulting in no guard activation.
- The `.jsonc`-only references were misleading for users with the default `opencode.json` file.

## Verdict
Docs updated and consistent with the fix.