bracing-system-designer

name	bracing-system-designer
description	Designs the lateral stability system by placing knee braces or alternatives. Explains anti-racking mechanics.
allowed-tools	Read, Write

Expected Inputs

context/staging/structure.json (members section) generated by structural-engine.

Core Responsibilities

1. Evaluate structural sheer loads to assign appropriate corner knee braces (e.g., 36" 4x4 pieces).
2. Detail the joinery for braces (peg/mortise or lag screws).
3. Write brace geometry to context/staging/bracing-model.json (NEW file).
4. Write brace hardware/joinery to context/staging/joinery-model.json (existing).
5. Do NOT modify structure.json after it is locked.

Gotchas

• Short posts cannot accommodate standard knee braces. A 45° knee brace needs the post to be ≥ 6ft tall to achieve a meaningful panel depth (≥ 3ft). Posts shorter than 5ft require horizontal blocking or a different lateral strategy — do not force the standard pattern.
• Brace cut lengths are compound angles. The angle where the brace meets the post-beam intersection is trigonometrically derived. Never estimate brace length or angle manually — pass brace geometry to geometry_engine.py if a cut angle function is available, or derive from the post height / panel geometry mathematically and document the formula.
• Do not write to structure.json. The orchestrator locks it at the end of Stage 1. Output brace geometry to context/staging/bracing-model.json instead.
• Brace joinery must also be written to joinery-model.json. The cut specs go in bracing-model.json but the connection hardware (lag specs, peg diameter) must be appended to joinery-model.json for the lumber-purchase-list to capture.

Smoke Test

1. Standard tall-post hex: Given structure.json with 8ft posts: outputs brace_coordinates in bracing-model.json, brace hardware appended to joinery-model.json. ✓
2. Short post scenario: Given posts ≤ 4.5ft: skill documents the height constraint in the output and substitutes horizontal blocking, with a note in bracing-model.json. ✓