diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -4,15 +4,18 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 5 SBC
 
 ## Project Status
 
-**Phase:** Component acquisition andplanning
+**Phase:** Component acquisition and planning
 
 - [x] Salvage analysis (K501U components)
 - [x] Display identification and controller board ordered
 - [x] SBC selection (Orange Pi 5 16GB)
 - [x] Storage architecture planned
 - [x] USB expansion design
-- [ ] Case design
+- [x] Case nomenclature and orientation defined
+- [x] Build approach: wooden case + salvaged lid canopy
+- [ ] Case design (dimensions, internal layout)
 - [ ] Power system (battery, charging)
+- [ ] Bow wall design (power input, fan exhaust)
 - [ ] Fabrication
 - [ ] Software configuration
 
@@ -50,6 +53,7 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 5 SBC
 - [Storage Architecture](docs/storage-architecture.md) - SD card + USB storage plan
 - [USB Expansion](docs/usb-expansion.md) - Hub selection and port allocation
 - [Parts List](docs/parts-list.md) - Bill of materials with costs
+- [Design Decisions](docs/design-decisions.md) - Build approach, nomenclature, layout
 
 ## Quick Reference
 
diff --git a/docs/design-decisions.md b/docs/design-decisions.md
new file mode 100644
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@@ -0,0 +1,41 @@
+# Design Decisions
+
+## Build Approach
+
+Wooden case with salvaged laptop lid (screen + hinge) as the canopy. Approximate briefcase dimensions, with the display panel setting minimum width and depth.
+
+## Salvage Exclusions
+
+- **Webcam:** Scrapped. Proprietary pinout, not worth reverse engineering.
+- **Keyboard/trackpad:** Proprietary connectors, not reusable.
+- **RAM:** DDR3L soldered, wrong generation.
+- **SSD:** Owner repurposed.
+- **WiFi card:** Intel 7265NGW needs M.2 E-key, OPi5 base lacks it.
+
+## Case Orientation & Nomenclature
+
+User sits at the **stern**, facing the **bow**. Hinge axis runs port-to-starboard along the bow edge.
+
+### Base (wooden enclosure)
+
+| Term | Surface | Notes |
+|------|---------|-------|
+| **Deck** | Top | Keyboard, controls, SBC access |
+| **Keel** | Bottom | Sits on table |
+| **Bow** | Back edge (spine side) | Power input, heat exhaust, farthest from user |
+| **Stern** | Front edge (lip side) | User-facing, keyboard near here |
+| **Port** | Left (facing bow) | |
+| **Starboard** | Right (facing bow) | |
+
+### Canopy (laptop lid + screen)
+
+| Term | Surface |
+|------|---------|
+| **Canopy dorsal** | Outside of lid |
+| **Canopy ventral** | Screen side |
+
+### Bow Wall Functions
+
+- Power input (barrel jack or USB-C PD)
+- Exhaust fans blowing away from user
+- Heat management surface