diff --git a/README.md b/README.md
index b3276ce..6654f79 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,94 @@
 
 ---
 
+## Build Profiles & Architecture
+
+**NexFS** implements a **modular Baukasten architecture** (SPEC-004) with three build profiles. Not one binary - three configurations compiled from modules:
+
+### Three Build Profiles
+
+| Profile | Modules | Footprint | Use Case |
+|---------|---------|-----------|----------|
+| **nexfs-core** | CAS + Block Valve + Hash | ~40KB | IoT, Satellite, Sensor |
+| **nexfs-sovereign** | core + CDC + DAG | ~120KB | Phone, Laptop, Desktop |
+| **nexfs-mesh** | sovereign + UTCP + Gossip | ~200KB | Home Box, Chapter Node |
+
+### Module Compilation
+
+NexFS uses Nim's compile-time conditionals for module selection:
+
+```nim
+# nexfs/config.nim
+const
+  nexfs_cas* = defined(nexfs_cas)    # CAS Layer (always)
+  nexfs_cdc* = defined(nexfs_cdc)    # Content-Defined Chunking
+  nexfs_mesh* = defined(nexfs_mesh)  # UTCP Cluster + Gossip
+  nexfs_dag* = defined(nexfs_dag)    # Merkle DAG Directories
+  nexfs_dedup* = defined(nexfs_dedup) # Cross-Node Dedup
+```
+
+**Build Commands:**
+```bash
+# Core profile (IoT sensor)
+nim c -d:nexfs_cas nexfs
+
+# Sovereign profile (laptop)
+nim c -d:nexfs_cas -d:nexfs_cdc -d:nexfs_dag nexfs
+
+# Mesh profile (home box)
+nim c -d:nexfs_cas -d:nexfs_cdc -d:nexfs_dag -d:nexfs_mesh nexfs
+```
+
+### Profile Comparison
+
+**nexfs-core** is your LittleFS successor:
+- ✅ Robust, power-safe
+- ✅ Content-addressed storage
+- ✅ Block-level wear leveling
+- ❌ No network code
+- ❌ No chunker
+- ❌ No gossip
+- **Target:** Root partition for everything that blinks and beeps
+
+**nexfs-sovereign** adds local intelligence:
+- ✅ CDC-Chunking for efficient snapshots
+- ✅ Local deduplication
+- ✅ Merkle DAGs for Time-Travel
+- ❌ Still single-node
+- **Target:** Phone, laptop, desktop
+
+**nexfs-mesh** enables network layer:
+- ✅ UTCP cluster communication
+- ✅ Gossip-based peer discovery
+- ✅ Cross-node deduplication
+- ✅ Chapter-Mesh integration
+- ✅ Kinetic Credits economy
+- **Target:** Home box, Chapter node
+
+---
+
+## Specifications
+
+NexFS is defined by three SPECs that build on each other:
+
+| SPEC | Name | Scope | Size |
+|------|------|-------|------|
+| **SPEC-084** | NexFS Core Format | Superblock, Block Pointers, Hash-ID, Profile-Byte | Foundation |
+| **SPEC-085** | NexFS Sovereign Extensions | CDC Chunking, Merkle DAG, Local Dedup, Time Travel | +80KB |
+| **SPEC-704** | UTCP Storage Extensions | UTCP Storage Ops, Gossip, Chapter-Mesh, Kinetic Credits | +80KB |
+
+**Dependency Chain:**
+```
+SPEC-084 (Core) → SPEC-085 (Sovereign) → SPEC-704 (Mesh)
+     ↓                    ↓                      ↓
+   40KB                +80KB                  +80KB
+   IoT                 Laptop                 Home Box
+```
+
+Each SPEC is **independently implementable**. `core` compiles without the others. `sovereign` needs `core`. `mesh` needs both.
+
+---
+
 ## Use Cases
 
 ### 1. Libertaria Mesh Nodes
@@ -155,6 +243,147 @@ pub const FlashInterface = struct {
 
 ---
 
+## Chapter-Mesh Architecture (nexfs-mesh)
+
+### The Strategic Moat
+
+When a user installs a Sovereign device, NexFS creates a two-partition layout:
+
+```
+┌─ /dev/nvme0 ─────────────────────────────────┐
+│                                              │
+│  Partition 1: nexfs-sovereign (Root, Private)│
+│  ├── /Cas (System, Immutable)                │
+│  ├── /Nexus (Config, Encrypted)              │
+│  └── /Data (User, Encrypted)                 │
+│                                              │
+│  Partition 2: nexfs-mesh (Chapter Pool)      │
+│  ├── Encrypted at rest (Monolith)            │
+│  ├── Auto-joins Chapter via UTCP Discovery   │
+│  ├── Contributes: Storage + Bandwidth        │
+│  └── Receives: Redundancy + Content Access   │
+│                                              │
+└────────────────────────────────────────────────┘
+```
+
+### Installation Flow
+
+```bash
+# During Sovereign installation
+nexus forge --chapter "frankfurt-01"
+
+# User prompt:
+# "How much storage do you want to contribute to the Chapter Network?"
+# [Slider: 10GB ... 500GB ... 2TB]
+# Default: 10% of disk or 50GB, whichever is smaller
+
+nexfs format /dev/nvme0p2 --mode sovereign-mesh \
+  --chapter-id "frankfurt-01" \
+  --quota 50G \
+  --replication-factor 3
+```
+
+### What Happens in the Background
+
+1. **UTCP Discovery** (SPEC-703 Pattern):
+   - Box broadcasts `PEER_ANNOUNCE` on local network
+   - Connects to known Chapter gateways
+
+2. **Gossip Sync**:
+   - Learns which other Sovereigns are online
+   - Exchanges peer lists and chunk availability
+
+3. **Lazy Replication**:
+   - Popular chunks (Nip packages, community content) automatically cached
+   - Replication factor enforced (default: 3 copies)
+
+4. **Sealed Storage**:
+   - User cannot see Chapter partition as normal directory
+   - It's an opaque block pool
+   - No user snooping on transit data possible
+
+### The Economy (Kinetic Credits)
+
+Integration with **Kinetic Economy Model** (SPEC-053):
+
+```
+You give: 100GB Mesh-Storage + Uptime
+You get:  Kinetic Credits
+You use:  Credits for Package-Downloads, Mesh-Access, Priority-Routing
+```
+
+**Engineered Reciprocity** - No altruism, no charity:
+- More contribution = more credits
+- No contribution = still can read (Commonwealth packages are free)
+- Premium content and priority bandwidth cost credits
+
+### The Torrent Killer
+
+**Why NexFS Chapter-Mesh beats BitTorrent:**
+
+| Feature | BitTorrent | NexFS Chapter-Mesh |
+|---------|------------|-------------------|
+| **FS Integration** | Separate client | Native FS (`nip install firefox`) |
+| **Deduplication** | Full file transfer | CAS-Dedup (5% delta transfer) |
+| **Encryption** | Optional | Encrypted at rest by default |
+| **NAT Traversal** | Problematic | UTCP CellID routing (no NAT issues) |
+| **Discovery** | Tracker/DHT | Gossip-based peer discovery |
+| **Economy** | None | Kinetic Credits |
+
+**Example:** Firefox 120.0.1 and 120.0.2 share 95% of chunks:
+- BitTorrent: Transfer entire `.tar.gz` again
+- NexFS: Transfer only 5% difference
+
+### Superblock Extension
+
+One byte in the superblock determines the profile:
+
+```nim
+type NexfsSuperblock* = object
+  magic*: uint32          # "NXFS"
+  version*: uint16
+  hash_algo*: uint8       # 0x00=BLAKE3-256, 0x01=BLAKE3-128, 0x02=XXH3-128
+  profile*: uint8         # 0x00=core, 0x01=sovereign, 0x02=mesh ← NEW
+  chapter_id*: CellID     # 128-bit (only for mesh, otherwise 0)
+  mesh_quota*: uint64     # Bytes dedicated to mesh (only for mesh)
+  replication_target*: uint8 # Desired copies (default 3)
+  # ... rest as usual
+```
+
+### Filesystem Hierarchy Extension
+
+```
+/Data/
+├── Volume/
+│   ├── Local/      # Standard
+│   ├── Remote/     # Cloud-Mounts
+│   ├── External/   # USB
+│   └── Mesh/       # NEW: Chapter Pool
+│       ├── .quota      # 50GB
+│       ├── .chapter-id # frankfurt-01
+│       └── .peers      # Known CellIDs
+```
+
+### UTCP Storage Protocol (SPEC-704)
+
+**Wire Protocol Extensions:**
+
+| Category | Operations | Size |
+|----------|-----------|------|
+| **Block Ops** | GET, PUT, DELETE, REPLICATE, VERIFY, REPAIR, STATS | 7 ops |
+| **DAG Ops** | RESOLVE, ANCESTORS, DIFF | 3 ops |
+| **Peer Ops** | ANNOUNCE, LEAVE, HEARTBEAT | 3 ops |
+
+All operations use **16-byte extension header** on existing UTCP frames.
+
+**Key Features:**
+- Gossip-based peer discovery
+- Credit-based flow control (SPEC-702 pattern reuse)
+- Replication-factor enforcement
+- Chapter-Mesh integration with Kinetic Credits
+
+---
+
 ## Quick Start
 
 ### Installation
@@ -344,24 +573,43 @@ const Config = struct {
 
 ## Roadmap
 
-### Version 0.2.0 (Q2 2026)
+### Version 0.2.0 (Q2 2026) - Sovereign Profile
+**Focus:** SPEC-085 Implementation
+- [ ] FastCDC chunker implementation
+- [ ] CAS store with inline dedup
+- [ ] Merkle DAG directory structure
+- [ ] TimeWarp snapshots (`nexfs snap create/rollback/diff`)
+- [ ] Build profiles: core vs sovereign
 - [ ] Active wear leveling algorithm
 - [ ] Bad block management
-- [ ] Power-loss recovery improvements
-- [ ] Extended file attributes (xattr)
 
-### Version 0.3.0 (Q3 2026)
+### Version 0.3.0 (Q3 2026) - Mesh Profile
+**Focus:** SPEC-704 Implementation
+- [ ] UTCP storage protocol (7 Block Ops, 3 DAG Ops, 3 Peer Ops)
+- [ ] Gossip-based peer discovery
+- [ ] Cross-node deduplication
+- [ ] Chapter-Mesh integration
+- [ ] Kinetic Credits integration
+- [ ] Credit-based flow control
 - [ ] Compression support (LZ4)
 - [ ] Defragmentation tool
 - [ ] Filesystem check utility (fsck)
-- [ ] Performance benchmarks
 
-### Version 1.0.0 (Q4 2026)
+### Version 1.0.0 (Q4 2026) - Production Hardening
+**Focus:** Production Readiness
 - [ ] Encryption support (XChaCha20-Poly1305)
-- [ ] Snapshot support
+- [ ] CRDT for concurrent DAG edits
+- [ ] Multi-Chapter federation
+- [ ] Performance benchmarks
 - [ ] Production-hardened
 - [ ] Full Libertaria stack integration
 
+### Future Considerations
+- **CRDT-Specification** for concurrent DAG edits (Phase 50+)
+- **Multi-Chapter-Federation** for cross-chapter chunk exchange (Phase 50+)
+
+**Note:** Features grow into existing SPECs as Sections when needed, not as standalone documents.
+
 ---
 
 ## Testing