diff --git a/.planning/ROADMAP.md b/.planning/ROADMAP.md
index d59fda4..bb5f83a 100644
--- a/.planning/ROADMAP.md
+++ b/.planning/ROADMAP.md
@@ -197,7 +197,7 @@ Plans:
 
 **Wave 3** *(blocked on Wave 2 completion)*
 
-- [ ] 05-03-PLAN.md — Secrets slice: encrypted cast, key management, organisations, credentials/OAuth tables
+- [x] 05-03-PLAN.md — Secrets slice: encrypted cast, key management, organisations, credentials/OAuth tables
 - [ ] 05-04-PLAN.md — Attachments: system_files, blob storage, thumbnails, delete lifecycle
 
 **Wave 4** *(blocked on Wave 3 completion)*
@@ -391,7 +391,7 @@ Phases execute in numeric order: 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 →
 | 2. API parity harness bootstrap | 5/5 | Complete   | 2026-09-17 |
 | 3. First vertical slice — genres end to end | 4/4 | Complete   | 2026-09-17 |
 | 4. CLI scaffolding, i18n and mail | 4/4 | Complete   | 2026-09-18 |
-| 5. Data layer full fidelity | 2/6 | In Progress|  |
+| 5. Data layer full fidelity | 3/6 | In Progress|  |
 | 6. HTTP routing, auth groups and rate limiting | 0/TBD | Not started | - |
 | 7. User plugin and authentication | 0/TBD | Not started | - |
 | 8. OAuth2.1 authorization server | 0/TBD | Not started | - |
diff --git a/.planning/STATE.md b/.planning/STATE.md
index c017c41..1f13cae 100644
--- a/.planning/STATE.md
+++ b/.planning/STATE.md
@@ -3,15 +3,15 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 05-02-PLAN.md
-last_updated: "2026-09-18T17:24:46.649Z"
+stopped_at: Completed 05-03-PLAN.md
+last_updated: "2026-09-18T17:44:19.083Z"
 last_activity: 2026-09-18
 progress:
   total_phases: 15
   completed_phases: 4
   total_plans: 23
-  completed_plans: 19
-  percent: 83
+  completed_plans: 20
+  percent: 87
 ---
 
 # Project State
@@ -26,11 +26,11 @@ See: .planning/PROJECT.md (updated 2026-09-16)
 ## Current Position
 
 Phase: 05 (data-layer-full-fidelity) — EXECUTING
-Plan: 3 of 6
+Plan: 4 of 6
 Status: Ready to execute
 Last activity: 2026-09-18
 
-Progress: [████████░░] 83%
+Progress: [█████████░] 87%
 
 ## Performance Metrics
 
@@ -65,6 +65,7 @@ Progress: [████████░░] 83%
 | Phase 04 P04-04 | 8 min | 3 tasks | 9 files |
 | Phase 05 P01 | 16 min | 4 tasks | 37 files |
 | Phase 05 P02 | 27 min | 3 tasks | 32 files |
+| Phase 05-data-layer-full-fidelity P03 | 15 min | 3 tasks | 28 files |
 
 ## Accumulated Context
 
@@ -130,6 +131,11 @@ Recent decisions affecting current work:
 - [Phase 05]: CollectionFillFields is name+description; PHP has no CollectionWriteService — D-05 service list is a subset of Fillable excluding owner_id
 - [Phase 05]: Various Artists natural key is name_key='various artists' (PHP seed), slug various-artists — seed_genre_and_various_artist_taxonomy.php uses a spaced name_key
 - [Phase 05]: go-playground/validator v10.30.4 is the STACK-named rule engine behind lagoon.Validate — STACK.md already named this library; lagoon.Validate translates Laravel rule strings onto Var()
+- [Phase 05]: Column keys are HKDF-SHA256 derived via Go 1.27 crypto/hkdf with info summercms.lagoon.encrypted.v1; no golang.org/x/crypto — D-11 stdlib-first: Go 1.24+ ships HKDF; CLAUDE.md forbids a new dependency here
+- [Phase 05]: Ciphertext is 1-byte format/key-id | 12-byte nonce | GCM seal, stored base64 in text columns — D-12 versioned ciphertext plus app.previous_keys decrypt-only fallback
+- [Phase 05]: OpenFromApp calls LoadAppKey+PublishEncryptionKeys once per boot; empty/short/undecodable app.key fails with SUMMER_APP__KEY — D-11 fail-loud, no default key; Scan/Value must not re-read config per row
+- [Phase 05]: golem15_user_organisations is owned by the user plugin; Phase 5 ships no users-table ALTER (D-03 deviation, Phase 7 AUTH-02) — User-confirmed at plan time: organisations are an FK target only this phase
+- [Phase 05]: DecryptLaravelPayload is cutover-import-only and is never called from Encrypted Scan/Value — D-10 live path is AES-256-GCM only; Laravel CBC is Phase 15 import
 
 ### Pending Todos
 
@@ -151,6 +157,6 @@ Items acknowledged and carried forward from previous milestone close:
 
 ## Session Continuity
 
-Last session: 2026-09-18T17:24:44.978Z
-Stopped at: Completed 05-02-PLAN.md
+Last session: 2026-09-18T17:43:22.041Z
+Stopped at: Completed 05-03-PLAN.md
 Resume file: None