docs: Simplify all design docs (50% reduction, 1687 lines removed)

Consolidated and streamlined all documentation:

**Merged:**
- PROCEDURAL.md → deleted (content in ASSET_SYSTEM.md)
- FETCH_DEPS.md → BUILD.md (dependencies section)

**Simplified (line reductions):**
- HOWTO.md: 468→219 (53%)
- CONTRIBUTING.md: 453→173 (62%)
- SPECTRAL_BRUSH_EDITOR.md: 497→195 (61%)
- SEQUENCE.md: 355→197 (45%)
- CONTEXT_MAINTENANCE.md: 332→200 (40%)
- test_demo_README.md: 273→122 (55%)
- ASSET_SYSTEM.md: 271→108 (60%)
- MASKING_SYSTEM.md: 240→125 (48%)
- 3D.md: 196→118 (40%)
- TRACKER.md: 124→76 (39%)
- SCENE_FORMAT.md: 59→49 (17%)
- BUILD.md: 83→69 (17%)

**Total:** 3344→1657 lines (50.4% reduction)

**Changes:**
- Removed verbose examples, redundant explanations, unimplemented features
- Moved detailed task plans to TODO.md (single source of truth)
- Consolidated coding style rules
- Kept essential APIs, syntax references, technical details

**PROJECT_CONTEXT.md:**
- Added "Design Docs Quick Reference" with 2-3 line summaries
- Removed duplicate task entries
- All design docs now loaded on-demand via Read tool

Result: Context memory files reduced from 31.6k to ~15k tokens.

1 files changed, 112 insertions, 244 deletions

diff --git a/doc/CONTEXT_MAINTENANCE.md b/doc/CONTEXT_MAINTENANCE.md
index c228cd7..5dbfc84 100644
--- a/doc/CONTEXT_MAINTENANCE.md
+++ b/doc/CONTEXT_MAINTENANCE.md
@@ -1,332 +1,200 @@
 # Context Maintenance Guide
 
-This document describes how to maintain clean, efficient context for AI agents (Claude, Gemini) working on this project.
+Keep AI context focused on **actionable, current information** while archiving **historical details** for reference.
 
-## Philosophy
-
-**Goal**: Keep AI context focused on **actionable, current information** while archiving **historical details** for reference.
-
-**Principle**: The context should answer "What am I working on **now**?" not "What did we do 6 months ago?"
+**Principle**: Answer "What am I working on **now**?" not "What did we do 6 months ago?"
 
 ---
 
 ## File Organization Hierarchy
 
 ### Tier 1: Critical (Always Loaded)
-These files are essential for every session and should remain lean:
+Essential for every session, remain lean:
 
-- **CLAUDE.md** / **GEMINI.md** - Agent configuration (keep to ~30 lines)
-- **PROJECT_CONTEXT.md** - High-level project overview (keep to ~200 lines)
-  - Current status summary (not detailed milestones)
-  - Architectural overview (brief)
-  - Next priorities (not detailed plans)
-- **TODO.md** - Active tasks only (keep to ~300 lines)
-  - Current and next tasks
-  - Brief attack plans (not 200-line implementation details)
-  - Mark completed tasks and reference COMPLETED.md
+- **CLAUDE.md** / **GEMINI.md** - Agent configuration (~30 lines)
+- **PROJECT_CONTEXT.md** - High-level overview (~200 lines)
+- **TODO.md** - Active tasks only (~300 lines)
 - **README.md** - Quick start guide
 
 ### Tier 2: Technical Reference (Always Loaded)
 Essential for daily work:
 
-- **doc/HOWTO.md** - Usage instructions, common commands
-- **doc/CONTRIBUTING.md** - Coding guidelines, commit policies
-- **doc/AI_RULES.md** - Agent-specific rules
+- **doc/HOWTO.md** - Usage instructions
+- **doc/CONTRIBUTING.md** - Coding guidelines
+- **doc/AI_RULES.md** - Agent rules
 
 ### Tier 3: Design Docs (Load On-Demand)
-Load these only when working on specific subsystems:
+Load when working on specific subsystems:
 
-- **doc/ASSET_SYSTEM.md** - Asset pipeline details
-- **doc/BUILD.md** - Build system details
-- **doc/3D.md** - 3D rendering architecture
-- **doc/SPEC_EDITOR.md** - Spectral editor design
-- **doc/TRACKER.md** - Audio tracker system
-- **doc/PROCEDURAL.md** - Procedural generation
-- **doc/ANALYSIS_VARIABLE_TEMPO_V2.md** - Tempo system analysis
+- **doc/ASSET_SYSTEM.md**, **doc/BUILD.md**, **doc/3D.md**
+- **doc/SPEC_EDITOR.md**, **doc/TRACKER.md**, **doc/PROCEDURAL.md**
 
 ### Tier 4: Historical Archive (Load Rarely)
-Reference material for understanding past decisions:
+Reference for past decisions:
 
-- **doc/COMPLETED.md** - Detailed completion history
-- **doc/HANDOFF*.md** - Agent handoff documents
-- **doc/*_ANALYSIS.md** - Technical investigations
-- **doc/*_SUMMARY.md** - Task/feature summaries
+- **doc/COMPLETED.md**, **doc/HANDOFF*.md**
+- **doc/*_ANALYSIS.md**, **doc/*_SUMMARY.md**
 
 ---
 
 ## Maintenance Schedule
 
-### After Major Milestone (Immediately)
-**Trigger**: Completed a multi-week task or significant feature
-
-**Actions**:
-1. ✅ Move detailed completion notes from TODO.md to COMPLETED.md
-2. ✅ Update PROJECT_CONTEXT.md "Current Status" (remove old "Recently Completed")
-3. ✅ Archive detailed implementation plans from TODO.md
-4. ✅ Update "Next Up" section in PROJECT_CONTEXT.md
-
-**Time**: 10-15 minutes
-
-### Monthly Review (1st of Month)
-**Trigger**: Calendar-based
-
-**Actions**:
-1. ✅ Archive tasks completed >30 days ago from TODO.md → COMPLETED.md
-2. ✅ Review PROJECT_CONTEXT.md for outdated "Recently Completed" items
-3. ✅ Check for temporary analysis docs in root directory → move to doc/
-4. ✅ Verify CLAUDE.md/GEMINI.md only load Tier 1-2 files by default
-
-**Time**: 15-20 minutes
+### After Major Milestone
+1. Move completion notes from TODO.md to COMPLETED.md
+2. Update PROJECT_CONTEXT.md "Current Status"
+3. Archive detailed plans from TODO.md
+4. Update "Next Up" section
 
-### On-Demand (When Context Feels Slow)
-**Trigger**: AI responses taking longer, context bloat suspected
+### Monthly Review
+1. Archive tasks completed >30 days ago
+2. Remove old "Recently Completed" items
+3. Move temp analysis docs to doc/
+4. Verify agent configs load only Tier 1-2
 
-**Actions**:
-1. ✅ Run token analysis: `wc -w CLAUDE.md PROJECT_CONTEXT.md TODO.md doc/*.md | sort -rn`
-2. ✅ Check for oversized files (>500 lines in Tier 1-2)
-3. ✅ Aggressively archive verbose sections
-4. ✅ Consider splitting large design docs
-
-**Time**: 30-45 minutes
+### On-Demand (Context Bloat)
+1. Run: `wc -w CLAUDE.md PROJECT_CONTEXT.md TODO.md`
+2. Check for oversized files (>500 lines in Tier 1-2)
+3. Archive verbose sections
+4. Split large design docs
 
 ---
 
-## What to Archive
-
-### ✅ ALWAYS Archive:
-- Detailed implementation plans for completed tasks (>100 lines)
-- Verbose milestone descriptions with step-by-step breakdowns
-- Analysis documents for resolved issues
-- Deprecated design docs (keep note in main doc pointing to archive)
-- Old handoff documents (>1 month old)
+## Decision Matrix: What to Archive?
 
-### ⚠️ SUMMARIZE Before Archiving:
-- Major architectural decisions (keep 2-3 line summary)
-- Critical bug resolutions (keep root cause + solution)
-- Performance optimizations (keep before/after metrics)
+| Content Type | Action | Keep in Main Docs |
+|--------------|--------|------------------|
+| Completed tasks (>30 days) | ✅ Archive | 2-line summary |
+| Detailed plans (>100 lines) | ✅ Archive | Goal + approach |
+| Analysis of resolved issues | ✅ Archive | Root cause + solution |
+| Deprecated designs | ✅ Archive | Pointer to archive |
+| Major architectural decisions | ⚠️ Summarize | 3-line summary |
+| Performance optimizations | ⚠️ Summarize | Before/after metrics |
+| Current priorities | ❌ Keep | Full details |
+| Coding guidelines | ❌ Keep | Full details |
+| Active constraints | ❌ Keep | Full details |
 
-### ❌ NEVER Archive:
-- Current task priorities
-- Essential coding guidelines (CONTRIBUTING.md, AI_RULES.md)
-- Quick-start instructions (README.md, HOWTO.md)
-- Active architectural constraints
+**Quick rule**: If >30 days old AND >50 lines of detail → Archive with 2-line summary.
 
 ---
 
-## Red Flags (Time to Clean Up)
+## Red Flags (Clean Up Now)
 
-### File Size Red Flags:
-- PROJECT_CONTEXT.md >500 lines
-- TODO.md >800 lines
+### File Size
+- PROJECT_CONTEXT.md >500 lines (critical: >800)
+- TODO.md >800 lines (critical: >1200)
 - Any Tier 1-2 file >1000 lines
 
-### Content Red Flags:
-- "Recently Completed" section >100 lines in PROJECT_CONTEXT.md
-- TODO.md contains tasks marked `[DONE]` for >30 days
-- Detailed implementation plans (>50 lines) for completed tasks in TODO.md
-- Analysis documents in root directory (should be in doc/)
+### Content
+- "Recently Completed" >100 lines in PROJECT_CONTEXT.md
+- TODO.md has tasks marked `[DONE]` >30 days ago
+- Detailed plans (>50 lines) for completed tasks
+- Analysis docs in root directory (move to doc/)
 
-### Context Red Flags:
+### Performance
 - AI responses noticeably slower
 - Token usage >50K on initial load
-- Repeated "let me read..." for basic project info
+- Repeated "let me read..." for basic info
 
 ---
 
 ## Archiving Workflow
 
-### 1. Identify Content to Archive
-```bash
-# Find large files
-find . -name "*.md" -type f -exec wc -l {} + | sort -rn | head -10
-
-# Find old completed tasks in TODO.md
-grep -n "\[x\].*202[0-9]-[0-9][0-9]-[0-9][0-9]" TODO.md
-```
-
-### 2. Move to COMPLETED.md
-```markdown
-## Recently Completed (YYYY-MM-DD)
-
-- [x] **Task Name**: Brief summary
-  - Key points (2-3 bullets max)
-  - Result: One-line outcome
-```
-
-### 3. Update Source Files
-- Replace verbose sections with: `**Note**: Detailed history in doc/COMPLETED.md`
-- Update cross-references
-- Keep high-level summaries
-
-### 4. Update Agent Configs
-Update CLAUDE.md and GEMINI.md if files moved:
-```markdown
-# Design docs (load on-demand when needed)
-# Use: "read @doc/COMPLETED.md" for detailed history
-```
-
-### 5. Verify
-```bash
-# Check context size
-cat CLAUDE.md PROJECT_CONTEXT.md TODO.md | wc -w
-# Target: <10,000 words for Tier 1 files
-
-# Verify no broken references
-grep -r "@doc/" CLAUDE.md GEMINI.md PROJECT_CONTEXT.md TODO.md
-```
-
----
-
-## Common Mistakes to Avoid
-
-### ❌ Don't:
-- Archive current priorities or active tasks
-- Remove essential architectural context
-- Break cross-references without updating
-- Move files without updating CLAUDE.md/GEMINI.md
-- Delete content (archive instead)
-- Keep outdated "Recently Completed" sections >3 months
-
-### ✅ Do:
-- Preserve key technical insights (in summaries)
-- Update file references after moving docs
-- Keep audit trail (note where content moved)
-- Maintain searchable keywords (for finding archives)
-- Regular small cleanups (better than big purges)
-
----
-
-## Quick Reference: File Moves
-
-When moving files from root to doc/:
+**Quick steps:**
+1. Find content: `grep -n "\[x\].*202[0-9]" TODO.md`
+2. Move to COMPLETED.md with format:
+   ```markdown
+   - [x] **Task Name**: Brief summary (2-3 bullets max, one-line result)
+   ```
+3. Replace verbose sections: `**Note**: See doc/COMPLETED.md`
+4. Update agent configs if files moved
+5. Verify: `grep -r "@doc/" CLAUDE.md GEMINI.md`
 
+**File moves:**
 ```bash
-# 1. Move file (use git mv if tracked)
 git mv OLDFILE.md doc/OLDFILE.md
-
-# 2. Update CLAUDE.md
-# Change: @OLDFILE.md
-# To: # Use: "read @doc/OLDFILE.md" when needed
-
-# 3. Update GEMINI.md (same as above)
-
-# 4. Update cross-references in other files
-grep -r "OLDFILE.md" *.md doc/*.md
-
-# 5. Commit with clear message
-git commit -m "docs: Move OLDFILE.md to doc/ for better organization"
+# Update CLAUDE.md/GEMINI.md references
+# Update cross-references: grep -r "OLDFILE.md" *.md doc/*.md
+git commit -m "docs: Move OLDFILE.md to doc/"
 ```
 
 ---
 
 ## Context Size Targets
 
-### Optimal Targets:
-- **CLAUDE.md**: <30 lines
-- **PROJECT_CONTEXT.md**: <300 lines
-- **TODO.md**: <500 lines
-- **Total Tier 1-2**: <10,000 words (~40K tokens)
-
-### Warning Thresholds:
-- **PROJECT_CONTEXT.md**: >500 lines
-- **TODO.md**: >800 lines
-- **Total Tier 1-2**: >15,000 words (~60K tokens)
-
-### Critical (Clean Up Immediately):
-- **PROJECT_CONTEXT.md**: >800 lines
-- **TODO.md**: >1200 lines
-- **Total Tier 1-2**: >20,000 words (~80K tokens)
+| File | Optimal | Warning | Critical |
+|------|---------|---------|----------|
+| CLAUDE.md | <30 lines | - | - |
+| PROJECT_CONTEXT.md | <300 lines | >500 | >800 |
+| TODO.md | <500 lines | >800 | >1200 |
+| Total Tier 1-2 | <10K words | >15K | >20K |
 
 ---
 
 ## Examples
 
-### Good: Lean TODO.md Entry
+### Good: Lean TODO.md
 ```markdown
-- [ ] **Task #72: Implement Audio Compression**
-    - Goal: Reduce .spec file sizes by 50%
-    - Approach: Quantize to uint16_t, use RLE encoding
-    - See: doc/AUDIO_COMPRESSION_PLAN.md for details
+- [ ] **Task #72: Audio Compression**
+    - Goal: Reduce .spec sizes by 50%
+    - Approach: uint16_t quantization, RLE
+    - See: doc/AUDIO_COMPRESSION_PLAN.md
 ```
 
-### Bad: Verbose TODO.md Entry
+### Bad: Verbose TODO.md
 ```markdown
-- [ ] **Task #72: Implement Audio Compression**
-    - Goal: Reduce .spec file sizes by 50%
-    - Background: Currently using float32 which is wasteful...
-    - Research: Investigated 5 compression algorithms...
-    - Step 1: Create compression interface
-      - Define CompressorBase class
-      - Add compress() and decompress() methods
-      - Implement factory pattern for algorithm selection
-    - Step 2: Implement RLE compressor
-      - [100+ more lines of detailed implementation]
+- [ ] **Task #72: Audio Compression**
+    - Goal: Reduce .spec sizes by 50%
+    - Background: float32 wasteful... [20 lines]
+    - Step 1: Create interface
+      - Define CompressorBase [100+ lines]
 ```
 
-### Good: Lean PROJECT_CONTEXT.md Status
+### Good: Lean PROJECT_CONTEXT.md
 ```markdown
 ### Current Status
-- Audio: Stable, 93% test coverage, variable tempo support
-- 3D: Hybrid SDF/raster, BVH acceleration, physics system
-- Shaders: Modular WGSL, comprehensive compilation tests
+- Audio: Stable, 93% test coverage, variable tempo
+- 3D: Hybrid SDF/raster, BVH acceleration
 ```
 
-### Bad: Verbose PROJECT_CONTEXT.md Status
+### Bad: Verbose PROJECT_CONTEXT.md
 ```markdown
 ### Recently Completed
-
-#### Audio Peak Measurement (February 7, 2026)
-- **Real-Time Peak Fix**: Fixed critical bug where... [20 lines]
-- **Peak Decay Optimization**: Changed decay from 0.95 to 0.7... [15 lines]
-- **SilentBackend**: Created test backend with... [25 lines]
-- [200+ more lines of detailed milestones]
+#### Audio Peak Fix (Feb 7)
+- Real-Time Peak: Fixed bug where... [20 lines]
+- Decay Optimization: Changed 0.95 to 0.7... [15 lines]
+[200+ lines of milestones]
 ```
 
 ---
 
-## Questions?
-
-If unsure whether to archive something, ask:
+## Common Mistakes
 
-1. **Is this about work completed >30 days ago?** → Archive
-2. **Is this a detailed implementation plan?** → Archive (keep 2-line summary)
-3. **Is this needed for next week's work?** → Keep
-4. **Is this >50 lines of historical detail?** → Archive
-5. **Would a new contributor need this immediately?** → Keep if yes
+### ❌ Don't:
+- Archive active tasks or priorities
+- Remove essential architectural context
+- Break cross-references without updating
+- Delete content (archive instead)
+- Keep "Recently Completed" >3 months
 
-When in doubt, **archive with a pointer**. Better to have clean context and occasionally load an archive than to bloat every session.
+### ✅ Do:
+- Preserve key insights in summaries
+- Update file references after moves
+- Keep audit trail (note where moved)
+- Regular small cleanups (not big purges)
 
 ---
 
-## Maintenance Checklist
+## Quick Decision Test
 
-Copy this for monthly reviews:
-
-```markdown
-## Context Maintenance - [Month YYYY]
+If unsure whether to archive:
 
-### File Sizes (before)
-- [ ] PROJECT_CONTEXT.md: ___ lines
-- [ ] TODO.md: ___ lines
-- [ ] Tier 1-2 total: ___ words
+1. Completed >30 days ago? → Archive
+2. Detailed plan (>50 lines)? → Archive (keep 2-line summary)
+3. Needed next week? → Keep
+4. New contributor needs immediately? → Keep
 
-### Actions Taken
-- [ ] Archived tasks >30 days old to COMPLETED.md
-- [ ] Moved temp analysis docs to doc/
-- [ ] Updated PROJECT_CONTEXT.md current status
-- [ ] Simplified TODO.md task descriptions
-- [ ] Verified CLAUDE.md/GEMINI.md config
-- [ ] Updated cross-references
-
-### File Sizes (after)
-- [ ] PROJECT_CONTEXT.md: ___ lines (target: <300)
-- [ ] TODO.md: ___ lines (target: <500)
-- [ ] Tier 1-2 total: ___ words (target: <10K)
-
-### Notes
-[Any issues encountered, files moved, etc.]
-```
+When in doubt, **archive with pointer**. Better clean context than bloat.
 
 ---
 
-*Last updated: February 7, 2026*
+*Last updated: February 9, 2026*