diff --git a/notes.md b/notes.md
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@@ -20,3 +20,11 @@
 - Env overrides: `COE_MIRROR_MATRIX_ROOM`, `COE_MIRROR_MATRIX_HOMESERVER`.
 - Pre-deploy step: invite `@intel-bot:m.mealeyfamily.com` to General once Synapse is back. Without joined membership, sends will 403.
 - DevTrack: #1172.
+
+## 2026-07-10 — mount_root guard (phantom pCloudDrive fix)
+
+- **Bug**: `probe_target()` did `TARGET_DIR.mkdir(parents=True, exist_ok=True)` unconditionally. When pCloud FUSE was unmounted, this created `~/pCloudDrive/...` as plain LOCAL dirs, occupying the mountpoint and blocking the pCloud client from mounting. Live state on carbon confirmed: `~/pCloudDrive` was a plain dir, not a mountpoint, with 22 stray zips inside.
+- **Fix**: new optional config key `mount_root` (env `COE_MIRROR_MOUNT_ROOT`). When set, `probe_target()` requires `os.path.ismount(mount_root)` AND that `TARGET_DIR` is under `mount_root` before any mkdir; otherwise returns False (queues to pending). Never creates the mount root. Empty/unset = old behavior (local targets like `~/coe-mirror`).
+- Local config sets `mount_root = "~/pCloudDrive"`.
+- **Recovery run**: stopped/masked timer, staged the 22 zips aside, removed the local `~/pCloudDrive`, relaunched pCloud, verified mountpoint, moved zips onto the live mount, unmasked timer.
+- DevTrack: #1307.