From 61ac1c5b1d93db339e587faa97bc29366ea45e8d Mon Sep 17 00:00:00 2001
From: cinnaboot <cinnaboot@protonmail.com>
Date: Sat, 3 Jan 2026 13:38:50 -0500
Subject: [PATCH] Add session notes and TODOs to config documentation
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Document session work including main.cpp refactoring and eccentric orbit
support. Add prioritized TODO list for remaining config file updates and
known issues with moon positions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
---
 docs/config_assumptions.md | 61 ++++++++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 5 deletions(-)

diff --git a/docs/config_assumptions.md b/docs/config_assumptions.md
index 1bda30f..8d7a868 100644
--- a/docs/config_assumptions.md
+++ b/docs/config_assumptions.md
@@ -3,7 +3,11 @@
 ## Recent Updates:
 - ✅ **FIXED**: Eccentric orbit support added via eccentricity and semi_major_axis parameters
 - ✅ **FIXED**: Binary star barycenter calculation
-- ⚠️ **TODO**: Moon and Jupiter's moons positions still incorrect in solar_system.txt
+- ✅ **FIXED**: Refactored main.cpp into focused functions (parse args, run_headless, run_gui)
+- ✅ **FIXED**: Added initial state capture in headless mode for comparison with final state
+- ⚠️ **TODO**: Update configs/solar_system.txt to new 12-field format
+- ⚠️ **TODO**: Update configs/example_binary_star.txt to new 12-field format
+- ⚠️ **TODO**: Fix Moon and Jupiter's moons positions in solar_system.txt
 
 ## Key Assumptions Found:
 
@@ -57,7 +61,54 @@ The code assumes **positions are absolute (heliocentric)**, but for child bodies
 
 ## Recommended Actions:
 
-1. Fix moon positions in solar_system.txt to be correct absolute coordinates
-2. Fix binary star system to have one star orbit the other (or implement barycenter)
-3. Document whether positions should be absolute or relative to parent
-4. Add validation to check if child body positions make sense relative to parent
+### High Priority:
+1. **Update config files to new format** - All config files need to be updated to 12-field format
+   - ⚠️ `configs/solar_system.txt` - Still uses old 10-field format
+   - ⚠️ `configs/example_binary_star.txt` - Still uses old 10-field format
+   - ✅ `configs/test_simple.txt` - Already updated
+
+2. **Fix moon positions** - Moon and Jupiter's moons use incorrect absolute coordinates
+   - Moon should be at ~(1.496e11 + 3.844e8, 0, 0) not (1.500e11, 0, 0)
+   - Jupiter's moons should be relative to Jupiter's position
+
+### Medium Priority:
+3. **Add config file validation** - Warn when child bodies seem incorrectly positioned
+4. **Document coordinate system** - Clarify that positions are absolute (heliocentric)
+
+### Low Priority:
+5. **Consider relative coordinate option** - Allow specifying child positions relative to parent
+6. **Add 3D orbit support** - Currently all orbits are in XY plane
+
+---
+
+## Session Notes (2026-01-03):
+
+### Changes Made:
+1. **Refactored main.cpp** - Broke 215-line main() into focused functions:
+   - `parse_command_line_args()` - Parse command line arguments into ProgramArgs struct
+   - `print_startup_info()` - Print simulation configuration
+   - `run_headless_simulation()` - Terminal-based simulation with initial/final state capture
+   - `run_gui_simulation()` - 3D visualization mode
+   - Main function now ~25 lines of setup and dispatch
+
+2. **Added eccentric orbit support**:
+   - Extended config format from 10 to 12 fields (added eccentricity, semi_major_axis)
+   - Implemented vis-viva equation: `v = sqrt(G*M*(2/r - 1/a))`
+   - Circular orbits: e=0, a=orbital_radius
+   - Elliptical orbits: e>0, a=semi_major_axis
+   - Renamed `calculate_initial_velocities_with_params()` → `calculate_velocities()`
+
+3. **Updated test_simple.txt**:
+   - Added Comet with highly eccentric orbit (e=0.7, a=2.5 AU)
+   - Perihelion: 0.75 AU, Aphelion: 4.25 AU
+   - Successfully tested - comet swings from 0.75 AU to ~3.8 AU
+
+4. **Documentation updates**:
+   - Updated README.md with new 12-field format and examples
+   - Updated this file with fixed issues and TODOs
+   - Added eccentric orbit feature to feature list
+
+### Known Issues:
+- **Old config files** still use 10-field format and need updating
+- **Moon positions** in solar_system.txt are physically incorrect
+- **No validation** for unrealistic body positions