chore: install openagent opencode

Signed-off-by: Dmytro Stanchiev <git@dmytros.dev>

.opencode/context/core/context-system/CHANGELOG.md

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+<!-- Context: core/CHANGELOG | Priority: low | Version: 1.0 | Updated: 2026-02-15 -->
+
+# Context System Changelog
+
+**Purpose**: Track major changes to the context system
+
+---
+
+## 2026-01-08: Navigation System Redesign
+
+### Major Changes
+
+1. **Renamed README.md → navigation.md**
+   - More descriptive filename
+   - Better discoverability
+   - Self-describing purpose
+
+2. **Added Concern-Based Organization Pattern**
+   - Pattern A: Function-Based (repository-specific)
+   - Pattern B: Concern-Based (multi-technology)
+   - Hybrid approach supported
+
+3. **Token-Efficient Navigation**
+   - Target: 200-300 tokens per navigation file
+   - ASCII trees for structure
+   - Tables for quick routes
+   - Concise descriptions (3-5 words)
+
+4. **Specialized Navigation Files**
+   - Cross-cutting concerns (e.g., `ui-navigation.md`)
+   - Task-focused routes
+   - Workflow-oriented
+
+5. **Self-Describing Filenames**
+   - `code.md` → `code-quality.md`
+   - `tests.md` → `test-coverage.md`
+   - `review.md` → `code-review.md`
+
+### New Documentation
+
+**Created**:
+- `guides/navigation-design.md` - How to create navigation files
+- `guides/organizing-context.md` - How to choose organizational pattern
+- `examples/navigation-examples.md` - Real-world examples
+
+**Updated**:
+- `context-system.md` - Added concern-based pattern, navigation principles
+- `standards/templates.md` - Added navigation templates
+
+### Organizational Decisions
+
+1. **Core Standards (Universal)**
+   - Location: `core/standards/`
+   - Scope: All projects, all languages
+   - Users can edit to affect global context flow
+
+2. **Development Principles (Domain-Specific)**
+   - Location: `development/principles/`
+   - Scope: Software engineering
+   - Both core standards and dev principles exist
+
+3. **Data Context**
+   - Location: `development/data/` (not top-level)
+   - Rationale: Data layer is part of development workflow
+
+4. **Specialized Navigation**
+   - Includes quick routes + common patterns
+   - Example: `fullstack-navigation.md` shows MERN, T3 stacks
+
+### Migration Path
+
+**Phase 0**: ✅ Update context system documentation (DONE)
+**Phase 1**: Rename navigation files, update core/
+**Phase 2**: Restructure development/ category
+**Phase 3**: Organize New-context-to-sort/
+**Phase 4**: Update all references
+
+---
+
+## Previous Changes
+
+### 2026-01-06: Initial Context System
+
+- Established MVI principle
+- Created function-based structure
+- Added file templates
+- Defined operations (harvest, extract, organize, update)