Session: Documentation restructuring and organization

Consolidated documentation structure:
- Merged duplicate coordinate frame sections into single coherent section
- Extracted rendering system to docs/rendering.md (308 lines)
- Extracted future work roadmap to docs/future_work.md (258 lines)
- Renamed implementation_plan.md → technical_reference.md for clarity
- Added spacecraft and maneuver config loader documentation
- Updated all cross-references (README.md, AGENTS.md, opencode.json)
- Removed obsolete AccelerationContext struct reference

Total: +646 lines documentation, 2 new files, 1 renamed

docs/session_summaries/2026-01-23-documentation-restructuring.md

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+# Session Summary: Documentation Restructuring
+
+**Date:** January 23, 2026
+**Session Length:** ~2 hours
+**Branch:** maneuvers
+
+---
+
+## Goals
+
+1. Consolidate duplicate coordinate frame sections into single coherent documentation
+2. Extract rendering system documentation into separate file
+3. Extract future work into dedicated roadmap document
+4. Rename main technical reference for clarity
+5. Update config loader documentation with spacecraft and maneuver support
+
+---
+
+## Work Completed
+
+### 1. Consolidated Coordinate Frame Documentation ✅
+
+**Issue:** Duplicate information in two sections:
+- "Coordinate Frame Strategy" (top-level after Technical Constraints)
+- "Local Coordinate Frames" (Module Overview subsection)
+
+**Solution:** Combined into single comprehensive "Coordinate Frame Strategy" section with:
+- Global Frame definition and usage
+- Local Frame definition and usage
+- Coordinate Frame Selection criteria
+- Benefits (numerical precision examples)
+- Key Functions
+- Implementation Details
+
+**Result:** Removed 18 lines of redundancy
+
+---
+
+### 2. Created Rendering System Documentation ✅
+
+**Created:** `docs/rendering.md` (308 lines)
+
+**Sections Included:**
+- Overview and RenderState structure
+- Coordinate transformation (XY to XZ plane)
+- Scaling factors (distance: 1e-9, size: 1e-9)
+- Camera system (setup, controls, follow mode)
+- Object rendering (bodies, spacecraft, maneuvers)
+- Orbit rendering (elliptical, parabolic, hyperbolic)
+- UI system (4 panels: info, body list, maneuver list)
+- Rendering pipeline sequence
+
+**Functions Documented:** 24 functions across initialization, camera, rendering, UI, scaling
+
+---
+
+### 3. Created Future Work Roadmap ✅
+
+**Created:** `docs/future_work.md` (258 lines)
+
+**Roadmap Sections:**
+- Immediate Priorities (Newton-Raphson integration, reference frame switching)
+- Mid-Term Enhancements (SOI transformations, moon stability)
+- Visualization Enhancements (3D orbits, visual highlighting, enhanced UI)
+- Advanced Physics (N-body, atmospheric drag, tidal forces)
+- Testing and Validation (expanded suite, benchmarks)
+- Data and Configuration (solar system data, scenarios)
+- Performance Optimizations (adaptive timestepping, multi-threading, GPU)
+- Documentation and Examples (tutorials, API docs)
+- Infrastructure (build system, CI/CD, debugging)
+- Research Directions (relativistic corrections, orbital determination)
+
+---
+
+### 4. Renamed Technical Reference ✅
+
+**Renamed:** `docs/implementation_plan.md` → `docs/technical_reference.md`
+
+**Rationale:** Title already says "Technical Reference" - better reflects purpose as LLM reference
+
+**Files Updated:**
+- `README.md`: Updated documentation link
+- `AGENTS.md`: Updated data structures reference
+- `opencode.json`: Updated instruction file path
+
+---
+
+### 5. Updated Config Loader Documentation ✅
+
+**Added to Key Functions:**
+- `load_system_config()` - main entry point
+- `parse_toml_spacecraft()` - parses spacecraft entries
+- `parse_toml_maneuver()` - parses maneuver entries
+- `load_spacecraft_from_toml()` - loads spacecraft array
+- `load_maneuvers_from_toml()` - loads maneuvers array
+- `initialize_bodies()` - combined initialization
+
+**Added Config Format Examples:**
+
+**Spacecraft:**
+```toml
+[[spacecraft]]
+name = "LEO_Satellite"
+mass = 1000.0
+position = { x = 0.0, y = 6.771e6, z = 0.0 }
+velocity = { x = 7660.0, y = 0.0, z = 0.0 }
+parent_index = 1
+```
+
+**Maneuver:**
+```toml
+[[maneuvers]]
+name = "orbit_raise"
+spacecraft_name = "LEO_Satellite"
+trigger_type = "time"
+trigger_value = 3600.0
+direction = "prograde"
+delta_v = 500.0
+```
+
+**Added Validation Rules (8 rules):**
+- Body/spacecraft/maneuver count limits
+- Parent index validation
+- Distance validation
+- Spacecraft reference validation
+- Maneuver name uniqueness
+
+**Updated Initialization Sequence:**
+- Reflects actual function calls
+- Shows 4-step `initialize_bodies()` process
+- Includes spacecraft global coordinates
+
+---
+
+### 6. Cleanup ✅
+
+**Removed from Technical Reference:**
+- `AccelerationContext` struct (no longer used)
+- "Implementation Status" section
+- "Scaling for Visualization" (moved to rendering.md)
+- Duplicate "Local Coordinate Frames" module section
+
+**Removed References:**
+- Updated README.md link to technical_reference.md
+- Updated AGENTS.md reference
+
+---
+
+## Documentation Structure
+
+### Before
+```
+docs/
+├── implementation_plan.md (449 lines)
+├── maneuver_planning_plan.md
+└── find_dominant_body_bug.md
+```
+
+### After
+```
+docs/
+├── technical_reference.md (426 lines)
+├── rendering.md (308 lines)         ← NEW
+├── future_work.md (258 lines)        ← NEW
+├── maneuver_planning_plan.md
+└── find_dominant_body_bug.md
+```
+
+**Total Documentation:** 992 lines across 3 main reference files
+
+---
+
+## Code Statistics
+
+### Files Created: 2
+- `docs/rendering.md`: +308 lines
+- `docs/future_work.md`: +258 lines
+
+### Files Modified: 2
+- `docs/technical_reference.md`: +171 insertions, -93 deletions = +78 lines
+- `AGENTS.md`: +2 lines (added rendering.md reference, updated technical_reference)
+
+### Files Renamed: 1
+- `docs/implementation_plan.md` → `docs/technical_reference.md`
+
+### Files Updated (references): 2
+- `README.md`: -1 +1 = 0 lines (link update)
+- `opencode.json`: -1 +1 = 0 lines (path update)
+
+### Total Changes
+- **Lines Added:** 742 lines
+- **Lines Removed:** 96 lines
+- **Net Change:** +646 lines
+
+---
+
+## Technical Decisions
+
+### 1. Section Consolidation
+- **Decision:** Combine coordinate frame sections into single top-level section
+- **Rationale:** Eliminates redundancy, single source of truth
+- **Result:** Cleaner documentation with no duplication
+
+### 2. File Naming
+- **Decision:** Rename `implementation_plan.md` → `technical_reference.md`
+- **Rationale:** Better reflects purpose as LLM reference, not implementation plan
+- **Result:** More accurate naming matching document title
+
+### 3. Document Separation
+- **Decision:** Extract rendering and future work into separate documents
+- **Rationale:** Main technical reference was getting too long (>400 lines), better separation of concerns
+- **Result:** 3 focused documents instead of 1 monolithic file
+
+### 4. Cross-References
+- **Decision:** Add links between documents rather than duplicating information
+- **Rationale:** Single source of truth, easier to maintain
+- **Result:** References in AGENTS.md and README.md updated
+
+---
+
+## Achievements
+
+1. ✅ **Eliminated Documentation Redundancy**
+   - Consolidated duplicate coordinate frame sections
+   - Removed AccelerationContext (obsolete)
+   - Single source of truth for each topic
+
+2. ✅ **Improved Documentation Organization**
+   - 3 focused documents instead of 1 large file
+   - Clear separation: technical reference, rendering, future work
+   - Better navigation for LLMs
+
+3. ✅ **Completed Missing Documentation**
+   - Full rendering system reference (308 lines)
+   - Comprehensive future work roadmap (258 lines)
+   - Spacecraft and maneuver config loader docs
+
+4. ✅ **Updated All References**
+   - README.md link updated
+   - AGENTS.md references updated
+   - opencode.json path updated
+
+5. ✅ **Maintained Build Integrity**
+   - All builds successful
+   - No code changes, only documentation
+
+---
+
+## Known Issues
+
+**None**
+
+All documentation restructured successfully with no build errors.
+
+---
+
+## Next Steps (When Returning)
+
+### High Priority
+1. **Spacecraft Maneuver Visualization**
+   - Add maneuver markers in 3D view
+   - Show burn direction vectors
+   - Display executed vs pending indicators
+
+2. **Interplanetary Maneuvers**
+   - Test maneuvers across SOI boundaries
+   - Validate frame transitions during burns
+   - Add interplanetary test configs
+
+### Medium Priority
+3. **Delta-V Budgeting**
+   - Track total delta-v used per spacecraft
+   - Add fuel capacity to config
+   - Display in UI and validate against available fuel
+
+4. **Maneuver Timeline**
+   - Show planned burns in chronological order
+   - Display predicted execution times
+   - Visual timeline in UI
+
+---
+
+## Session Outcome
+
+**Productive session** - Successfully restructured project documentation:
+
+- Eliminated redundancy and consolidated duplicate sections
+- Created comprehensive rendering system reference
+- Established clear future work roadmap
+- Renamed main technical reference for clarity
+- Updated all cross-references
+- Added missing spacecraft and maneuver config documentation
+
+**Core Achievement:** Documentation is now well-organized with 3 focused documents instead of 1 monolithic file, improving maintainability and LLM comprehension.
+
+**Net Change:** +646 lines of documentation, 2 new files, 1 renamed file, all references updated.