diff --git a/docs/design/EPIC-001-First-Verified-Decision.md b/docs/design/EPIC-001-First-Verified-Decision.md
index a3157ed10..4e761fe4a 100644
--- a/docs/design/EPIC-001-First-Verified-Decision.md
+++ b/docs/design/EPIC-001-First-Verified-Decision.md
@@ -377,6 +377,19 @@ These are important but don't help reach the first verified workflow.
 
 **Architecture Goal:** Every artifact must be traceable backward to its source and forward to its decision.
 
+**Architecture Principle:**
+**LandveX Intelligence Lab does not produce AI results. It produces verified Decision Cases through a reproducible and traceable pipeline.**
+
+## Core Objects
+
+Three fundamental objects:
+
+| Object | Purpose |
+|--------|---------|
+| **Session** | Organizes field work |
+| **Artifact** | Organizes everything produced (video, dataset, models, reports, Decision Cases) |
+| **Event** | Organizes history and makes the entire chain reproducible |
+
 ## Development Rule
 
 **No Story may start with UI. Every Story starts with:**
@@ -388,14 +401,205 @@ These are important but don't help reach the first verified workflow.
 
 This keeps architecture clean and allows testing each part without frontend.
 
+## Hierarchy
+
+```
+Field Session
+    ↓
+Mission
+    ↓
+Mission Asset
+    ↓
+Observation
+    ↓
+Evidence
+    ↓
+Finding
+    ↓
+Decision
+    ↓
+Action
+    ↓
+Outcome
+```
+
+**Session is the root.** A pilot day produces many missions.
+
+## Event Sourcing
+
+**Never overwrite status. Status is a projection of history.**
+
+```
+MissionCreated
+    ↓
+AssetUploaded
+    ↓
+AssetValidated
+    ↓
+ObservationCreated
+    ↓
+EvidenceLinked
+    ↓
+DecisionApproved
+```
+
+Always replayable.
+
+## Artifact Registry
+
+First-class object. Not just buckets.
+
+```
+Artifact
+├── id
+├── type           // video | dataset | model | decision_case | evaluation_report | replay
+├── version
+├── hash
+├── created
+├── created_by
+├── storage_uri
+├── parent
+└── lineage
+```
+
+Everything becomes traceable.
+
+## Decision Case Immutability
+
+Never modify a Decision Case.
+
+```
+Decision Case
+    ↓
+Review
+    ↓
+Revision
+    ↓
+Approved Version
+```
+
+Like Git.
+
+## Review Task
+
+```
+Review Task
+    ↓
+Assigned
+    ↓
+Reviewed
+    ↓
+Approved
+    ↓
+Closed
+```
+
+Makes future quality assurance much easier.
+
+## Processing Graph
+
+Not a list of pipelines. Each step is a node.
+
+```
+Mission
+    ↓
+Dataset
+    ↓
+Annotation
+    ↓
+Evaluation
+    ↓
+Decision
+    ↓
+Learning
+```
+
+Swap models without changing the rest:
+```
+YOLO → Grounding DINO → Custom model
+```
+
+## Data Quality Domain
+
+```
+Quality Issue
+├── Blur
+├── Duplicate
+├── Bad GPS
+├── Low Resolution
+├── Missing Metadata
+├── Wrong Timestamp
+└── Occlusion
+```
+
+Then: Quality Report.
+
+## Decision Case Comparison
+
+```
+Decision A
+    ↓
+Decision B
+```
+
+Show exactly:
+- What changed?
+- Which evidence?
+- Which confidence?
+- Which model?
+- Which human?
+
+## Golden Missions & Golden Datasets
+
+| Level | Description |
+|-------|-------------|
+| **Golden Mission** | Real mission that never changes |
+| **Golden Dataset** | Selected observations from Golden Mission |
+
+## Domain Event Viewer
+
+Timeline, not logs:
+
+```
+09:42  Mission Created
+09:43  Video Uploaded
+09:44  GPS Extracted
+09:45  AI Analysis
+09:47  Human Review
+09:50  Decision Approved
+```
+
+Incredibly useful.
+
+## KPI: Verified Decision Throughput
+
+Not number of models. Not number of missions.
+
+```
+Verified Decision Throughput = Verified decisions per day
+```
+
+This is your factory capacity.
+
 ## Story 1: Mission Import — Implementation Plan
 
 ### PR-001: Domain Model
 
 ```typescript
+// FieldSession
+interface FieldSession {
+  id: string;           // session_20260814_000001
+  location: Location;
+  date: Date;
+  status: SessionStatus;
+  missions: string[];   // mission IDs
+  createdAt: Date;
+}
+
 // Mission
 interface Mission {
   id: string;           // mission_20260814_000123
+  sessionId: string;
   status: MissionStatus;
   location: Location;
   device: Device;
@@ -433,9 +637,23 @@ interface Upload {
   completedAt?: Date;
 }
 
+// Artifact
+interface Artifact {
+  id: string;
+  type: ArtifactType;
+  version: number;
+  hash: string;
+  createdBy: string;
+  storageUri: string;
+  parentId?: string;
+  lineage: string[];
+}
+
 // Enums
+type SessionStatus = 'planned' | 'active' | 'completed';
 type MissionStatus = 'created' | 'uploading' | 'processing' | 'completed' | 'failed';
 type AssetType = 'image' | 'video';
+type ArtifactType = 'video' | 'dataset' | 'model' | 'decision_case' | 'evaluation_report' | 'replay';
 type UploadStatus = 'pending' | 'in_progress' | 'completed' | 'failed';
 ```
 
@@ -453,8 +671,11 @@ type UploadStatus = 'pending' | 'in_progress' | 'completed' | 'failed';
 ### PR-003: API
 
 ```
-POST   /missions
+POST   /sessions
+POST   /sessions/{id}/missions
 POST   /missions/{id}/assets
+GET    /sessions/{id}
+GET    /sessions
 GET    /missions/{id}
 GET    /missions
 ```
@@ -462,10 +683,14 @@ GET    /missions
 ### PR-004: Events
 
 ```
+SessionCreated
+    ↓
 MissionCreated
-↓
+    ↓
 AssetUploaded
-↓
+    ↓
+AssetValidated
+    ↓
 RawDatasetReady
 ```
 
@@ -501,6 +726,7 @@ This is the first proof.
 
 | Entity | ID Format | Example |
 |--------|-----------|---------|
+| Session | `session_YYYYMMDD_NNNNNN` | `session_20260814_000001` |
 | Mission | `mission_YYYYMMDD_NNNNNN` | `mission_20260814_000123` |
 | Asset | `asset_NNNNNN` | `asset_000456` |
 | Observation | `obs_NNNNNN` | `obs_000981` |