opencode: add OAC

opencode/context/core/context-system/guides/navigation-design-basics.md

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+<!-- Context: core/navigation-design-basics | Priority: high | Version: 1.0 | Updated: 2026-02-15 -->
+
+# Guide: Designing Navigation Files
+
+**Purpose**: How to create token-efficient, scannable navigation files
+
+---
+
+## Prerequisites
+
+- Understand MVI principle (`context-system/standards/mvi.md`)
+- Know your category's organizational pattern
+- Have content files already created
+
+**Estimated time**: 15-20 min per navigation file
+
+---
+
+## Core Principles
+
+### 1. Token Efficiency
+**Goal**: 200-300 tokens per navigation file
+
+**How**:
+- Use ASCII trees (not verbose descriptions)
+- Use tables (not paragraphs)
+- Be concise (not comprehensive)
+
+### 2. Scannable Structure
+**Goal**: AI can find what it needs in <5 seconds
+
+**Format**:
+1. **Structure** (ASCII tree) - See what exists
+2. **Quick Routes** (table) - Jump to common tasks
+3. **By Concern/Type** (sections) - Browse by category
+
+### 3. Self-Contained
+**Include**: ✅ Paths | ✅ Brief descriptions (3-5 words) | ✅ When to use
+**Exclude**: ❌ File contents | ❌ Detailed explanations | ❌ Duplicates
+
+---
+
+## Steps
+
+### 1. Determine Navigation Type
+
+| Type | Path | Purpose |
+|------|------|---------|
+| Category-level | `{category}/navigation.md` | Overview of category |
+| Subcategory-level | `{category}/{sub}/navigation.md` | Files in subcategory |
+| Specialized | `{category}/{domain}-navigation.md` | Cross-cutting (e.g., ui-navigation.md) |
+
+### 2. Create Structure Section
+
+```markdown
+## Structure
+
+```
+openagents-repo/
+├── navigation.md
+├── quick-start.md
+├── concepts/
+│   └── subagent-testing-modes.md
+├── guides/
+│   ├── adding-agent.md
+│   └── testing-agent.md
+└── lookup/
+    └── commands.md
+```
+```
+
+**Token count**: ~50-100 tokens
+
+### 3. Create Quick Routes Table
+
+```markdown
+## Quick Routes
+
+| Task | Path |
+|------|------|
+| **Add agent** | `guides/adding-agent.md` |
+| **Test agent** | `guides/testing-agent.md` |
+| **Find files** | `lookup/file-locations.md` |
+```
+
+**Guidelines**: Use **bold** for tasks | Relative paths | 5-10 common tasks
+
+### 4. Create By Concern/Type Sections
+
+```markdown
+## By Type
+
+**Concepts** → Core ideas and principles
+**Guides** → Step-by-step workflows
+**Lookup** → Quick reference tables
+**Errors** → Troubleshooting
+```
+
+### 5. Add Related Context (Optional)
+
+```markdown
+## Related Context
+
+- **Core Standards** → `../core/standards/navigation.md`
+```
+
+### 6. Validate Token Count
+
+**Target**: 200-300 tokens
+
+```bash
+wc -w navigation.md  # Multiply by 1.3 for token estimate
+```
+
+---
+
+## Verification Checklist
+
+- [ ] Token count 200-300?
+- [ ] ASCII tree included?
+- [ ] Quick routes table?
+- [ ] By concern/type section?
+- [ ] Relative paths?
+- [ ] Descriptions 3-5 words?
+- [ ] No duplicate information?
+
+---
+
+## Related
+
+- `navigation-templates.md` - Ready-to-use templates
+- `../standards/mvi.md` - MVI principle
+- `../examples/navigation-examples.md` - More examples