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MERGED SESSION SUMMARY: OpenBallistics ↔ py-ballisticcalc Parity Debugging

APPROACHES TRIED

Debugger-Based RK4 Investigation (Multi-phase, Systematic)

• Phase 1: Set MCP breakpoints at RK4 step boundaries (Python rk4.py:235, Kotlin TrajectorySolver.kt:321)
• Extracted k1-k4 y-component values at steps 1-2 of zero-finding and main trajectory
• Phase 2: Compared internal state variables: km, density_ratio, mach, speed of sound, cd, vRelMag, gravity, coriolis
• Finding: All RK4 internal calculations match to 1e-13 floating-point precision; divergence is purely initial conditions
• Phase 3: Tested altitude-dependent density path (step 88 where |y| > 30ft threshold kicks in)

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k1-k4 y-Component Comparison: Python vs Kotlin (RK4 Step 2)

Setup

• Python: debug_py_step.py suspended at line 235 of rk4.py (velocity_vector += line), step 2 of calc.fire().
• Kotlin: DebugOneStep.kt suspended at line 321 of TrajectorySolver.kt (return State( line), step 2 of computeTrajectory().

Both breakpoints capture all k1-k4 values AFTER they are computed but BEFORE the state update.

Conversion factor: 1/3.2808399 (= Kotlin's FPS_PER_MPS inverse)

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#!/usr/bin/env python3
from py_ballisticcalc import (
    Ammo, Angular, Atmo, Calculator, Distance, DragModel,
    Pressure, Shot, TableG7, Temperature, Velocity, Weapon, Weight, Wind,
)

bc = 0.209
dm = DragModel(bc=bc, drag_table=TableG7,
               weight=Weight.Grain(77.0),
               diameter=Distance.Millimeter(5.56),

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#!/usr/bin/env python3
"""PR #3381 — Single-command outlet test.

Usage: python3 .ai/bug4-outlet-toggle-test.py <test> [port]

Tests:
  og1.off.le    SOG_0 (OG1) OFF, LE word order
  og1.on.le     SOG_0 (OG1) ON,  LE word order
  og1.off.be    SOG_0 (OG1) OFF, BE word order
  og1.on.be     SOG_0 (OG1) ON,  BE word order

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#!/usr/bin/env python3
"""Test EchterAgo's probe idea: write CANCEL|OUTPUT_ON|OUTPUT_OFF to OutletCommand_BF.

On spec-compliant firmware: EMBXILVAL (invalid command combo detected)  
On LE-buggy firmware: different error or no error (combo lands in reserved bits)

Must run with NUT driver stopped: systemctl stop nut-driver@apc
"""
import sys

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#!/usr/bin/env python3
"""Test: Modbus/TCP word order via APC NMC.

Reads raw register values to verify read word order, then tests write
word order for OutletCommand (load.on) in both big-endian and little-endian.

Safe: load.on while already on is a NOOP.

Usage:
    python3 bug4-test-modbus-tcp.py <NMC_HOST> [NMC_PORT]

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#!/usr/bin/env python3
"""Bug 4 — Test: Confirm word-order bug in apc_modbus OutletCommand writes.

The NUT driver's _apc_modbus_from_uint64() stores 32-bit values in big-endian
word order: [MSW, LSW]. But APC UPS expects little-endian: [LSW, MSW].

For command value 0x0102 (load.on + MOG):
  - NUT sends:     [0x0000, 0x0102] → FAILS (value in wrong register)
  - Correct:       [0x0102, 0x0000] → WORKS (value in register 1538)

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#!/usr/bin/env python3
"""Bug 4 — Test: Does setting SOURCE_RJ45_PORT bit fix OutletCommand writes?

This script bypasses the NUT driver and sends a raw Modbus write to register
1538 (OutletCommand_BF) with the SOURCE_RJ45_PORT bit (bit 14) set.

Command: load.on targeting MOG (Main Outlet Group)
  - Without source bit:  0x0102 = CMD_OUTPUT_ON | TARGET_MOG
  - With source bit:     0x4102 = CMD_OUTPUT_ON | TARGET_MOG | SOURCE_RJ45_PORT

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{
	"mcpServers": {
		"github": {
			"command": "docker",
			"args": [
				"run",
				"-i",
				"--rm",
				"-e",
				"GITHUB_PERSONAL_ACCESS_TOKEN",

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#!/usr/bin/env python
"""Fetch unresolved review comments from a GitHub PR.

Based on: https://stackoverflow.com/a/66072198/844449

Usage:
    python scripts/gh-comments.py [PR_NUMBER]
    python scripts/gh-comments.py 17
"""