Key Design View's parked FX-offline state to the FX's own GUID, not its slot

view_state v2 writes identities beside the v1 slot array, so a downgrade keeps
what it had. An FX gone at restore time is dropped and reported, never restored
onto whatever took its place.

src/core/view/CLAUDE.md

@@ -42,7 +42,9 @@ settled 2026-07-23):
   reapply touches solo not at all.
 - **GUID-keyed, reorder-safe.** Membership keys on track GUID (`GetTrackGUID`),
   never track index; tolerates unknown/stale GUIDs (pruned on reconcile via
-  `ViewModeModel::reconcile(liveGuids)`).
+  `ViewModeModel::reconcile(liveGuids)`). The same rule binds one level down: a
+  parked track's per-FX offline state keys on the FX's own identity
+  (`TrackFX_GetFXGUID`), never its slot — see `fx_offline`.
 - **Relative/portable state only** in the persisted view section (GUID strings,
   mode ids — no absolute paths, no index positions).
 - **Show-both semantics.** A per-track "pin visible across modes" flag that
@@ -95,6 +97,7 @@ settled 2026-07-23):
 ## Modules
 
 - `view_mode_model` — Design View mode system: mode registry, GUID-keyed membership, folder-tree-aware visibility derivation, snapshot-based park/restore planner, the per-mode `SoloCache` it owns, JSON round-trip.
+- `fx_offline` — the per-FX offline snapshot's KEY and its restore resolution: `FxKeying` (Identity / Slot), `FxOfflineState`, the planned `FxOfflineOp`, and `resolveFxRestore`, which matches each captured state to the FX it came from against the chain as it stands at restore time. An identity that is no longer live is DROPPED and counted (`FxRestoreDrops`, reported through `describeFxRestoreDrops`), never re-pointed at a slot — the slot fallback is precisely the reorder bug identity keying exists to close. Slot keying survives only for snapshots lifted from a pre-identity `view_state` and for park plans, where every live slot is the target by construction.
 - `solo_cache` — the per-mode solo surface: `SoloCache` (mode id → GUID → raw `I_SOLO`), the soloed-subset filter, and `planSoloRestore`, whose two drop rules (dead GUID, not visible in the incoming mode) and their reasoning live in its header.
 - `view_tree` — pure `I_FOLDERDEPTH`→FolderTree helper for the Design View shell.
 - `mode_switch` — REAPER-free segment layout + hit-test for the bank_panel's Design View mode switch.
@@ -110,6 +113,11 @@ settled 2026-07-23):
 - `kManagedLanePrefix` ("reasampler:") is stable-forever like an action-id
   string — changing it strands the ownership of every already-minted lane in
   every already-saved project.
+- The `view_state` blob's version ladder lives beside `kViewStateVersion` in
+  `view_mode_model.cpp`. v2 writes the v1 slot array BESIDE the identity array so
+  a downgrade keeps the behavior it had; the version field is written but
+  deliberately not validated on read, because an unreadable `view_state` falls
+  back to a default model and loses every membership tag.
 - `guid_diff::GuidBaseline` must have `reset()` called on every detected
   project switch, or the next `observe()` will diff across two unrelated
   projects and mass-tag (or miss) content.