docs: insert Phase 12.2 admin form fields with deferred binding (v0.1.1)

.planning/ROADMAP.md

@@ -654,6 +654,27 @@ Plans:
 Plans:
 - [ ] TBD (run /gsd-plan-phase 12.1 to break down)
 
+### Phase 12.2: Admin form fields: date, file upload, relation editing with deferred binding (INSERTED)
+
+**Goal:** A plugin's admin forms cover the three gaps a downstream project on SummerCMS v0.1 hit: a date/datetime field, a file upload field, and creating, editing and deleting related records inside the parent form (WinterCMS RelationController parity). Uploads and related-record changes on a record that is not saved yet use Winter-like deferred binding: they are held against a session key and committed with the parent's first save, or discarded with it.
+**Requirements**: TBD
+**Depends on:** Phase 9 (cabana form schema and relation-manager), Phase 12 plan 12-01 (`lagoon/attach` public URLs, webp, image-dimension guard)
+**Repos:** summercms.go only (`modules/cabana`, `modules/lagoon/attach`, the admin SPA); framework READMEs and `docs/` updated in the same change
+**Release:** ships as tag v0.1.1
+**Ordering:** urgent; independent of Phase 12.1 and Phase 13, and Phase 12.1's relation managers can use it
+**Success Criteria** (what must be TRUE):
+
+  1. `fields.yaml` accepts `type: datepicker` with Winter's `mode` (date, datetime, time) and stores date, timestamp and time columns without a plugin defining its own date types.
+  2. `type: fileupload` handles `attachOne` and `attachMany` relations: upload with size and MIME limits from the field config, image preview and thumbnail, remove, and reorder for `attachMany`. It works on both saved and unsaved records.
+  3. The relation manager creates, updates and deletes `hasMany` (and `belongsToMany` with pivot) related records in a modal driven by the related model's `fields.yaml`, alongside the existing link and unlink. Every child endpoint is scoped to its parent record, so a child of another parent can be neither read nor changed.
+  4. Deferred binding: on an unsaved parent, uploads and related-record changes bind to a session key, are committed in the parent's create transaction, and are discarded with the session. Orphaned deferred bindings and their files are purged.
+  5. The new code has unit tests, delivered in the phase's last plan, and the docs checker passes.
+
+**Plans:** 0 plans
+
+Plans:
+- [ ] TBD (run /gsd-plan-phase 12.2 to break down)
+
 ### Phase 13: Płytarium API — wishlist, notifications, CSV, credentials, public routes
 
 **Goal**: The remaining core API surface — wishlist, notifications, CSV import/export, per-user/org credentials, and onboarding/public/invitation routes — is ported with byte-compatible shapes and their own public rate-limit buckets.

.planning/STATE.md

@@ -5,12 +5,12 @@ current_phase: 12
 current_phase_name: Płytarium API — Collections and Albums
 status: executing
 stopped_at: Completed 12-03-PLAN.md
-last_updated: "2026-10-02T11:18:14.935Z"
+last_updated: "2026-10-02T12:36:15.774Z"
 last_activity: 2026-10-02
 last_activity_desc: Phase 12 execution started
-state_head: 6f37a3782f59f1d786016197f485c6d8f466e38e
+state_head: 66497635906aea588e28ba6d34afc6576423a662
 progress:
-  total_phases: 20
+  total_phases: 21
   completed_phases: 10
   total_plans: 101
   completed_plans: 99
@@ -168,6 +168,7 @@ Progress: [██████░░░░] 60%
 - Phase 11.3 inserted after Phase 11.2: Newsletter plugin and signup on summercms.io (split out of the original 11.2)
 - Phase 11.3 deferred to the backlog as Phase 999.1 (2026-10-02): the Journal plugin and delivering Płytarium take priority
 - Phase 12.1 inserted after Phase 12: User plugin admin screens (sm-user-plugin): Users, User Groups, Organisations admin, before Phase 15 cutover
+- Phase 12.2 inserted after Phase 12: Admin form fields: date picker, file upload and relation-manager create/update/delete with Winter-like deferred binding (RelationController parity); framework only, ships as tag v0.1.1; blocks a downstream project on v0.1 (URGENT)
 
 ### Decisions