crash-analysis

name	crash-analysis
description	Analyze MAGDA crash logs and Windows minidumps. Use when the user reports a crash, provides a crash log or .dmp file, or asks to investigate a crash.

Crash Analysis

Parsing Crash Logs

Never read crash log files directly — they are huge and waste context. Use the parser script:

# Extract crashed thread only (default)
.claude/skills/crash-analysis/parse-crash.sh <crash-file>

# Extract all threads (when you need more context)
.claude/skills/crash-analysis/parse-crash.sh <crash-file> --all-threads

Supports both .ips (JSON, modern macOS) and .crash (text, older) formats.

Finding Crash Logs

macOS crash logs are stored at:

~/Library/Logs/DiagnosticReports/MAGDA-*.ips

To find the most recent crash:

ls -t ~/Library/Logs/DiagnosticReports/MAGDA-*.ips | head -1

Analysis Workflow

1. Parse the crash log with the script
2. Identify the crash type (SIGSEGV, SIGABRT, EXC_BAD_ACCESS, etc.)
3. Look at the top frames for MAGDA code (source file + line number are included)
4. If the crash is in a third-party plugin (e.g. "Kick 3", "Serum"), note it — host can't fix plugin bugs
5. If the crash is in JUCE internals, check what MAGDA code triggered it (look further down the stack)
6. Search the codebase for the relevant source file and line to understand the bug

Common Crash Patterns

Signal	Meaning	Typical Cause
SIGSEGV (EXC_BAD_ACCESS)	Null/dangling pointer	Use-after-free, null deref
SIGABRT	Assertion/abort	JUCE assertion, malloc corruption, std::abort
EXC_BAD_INSTRUCTION	Illegal instruction	Undefined behavior, bad vtable
EXC_BREAKPOINT	Debugger trap	__builtin_trap, Swift precondition

Plugin crashes during shutdown

If the crash is in a plugin dylib during exit() / __cxa_finalize_ranges, it's a buggy plugin static destructor. The _exit(0) workaround in magda_daw_main.cpp should prevent these.

Timer callback crashes

Crashes in juce::Timer::TimerThread::callTimers() often mean a component was deleted while its timer was still running. Check that stopTimer() is called in destructors.

Audio thread crashes

Crashes in threads named "JUCE Audio" or "Tracktion" are audio-thread issues. Common causes: allocating memory, locking mutexes, or accessing deleted objects from the audio callback.

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Windows Crash Analysis (.dmp files)

Windows users send .dmp minidump files. Use the scripts below — never read .dmp files directly.

Quick parse (no symbols)

python3 .claude/skills/crash-analysis/parse-minidump.py /path/to/file.dmp

With PDB symbolization (function names + offsets)

From v0.4.6 onwards, each release includes MAGDA-X.Y.Z-Windows-x86_64.pdb. Download it from the GitHub release assets, then:

python3 .claude/skills/crash-analysis/parse-minidump.py file.dmp --pdb MAGDA-X.Y.Z-Windows-x86_64.pdb

Semi-automated analysis (parse + Claude + optional Linear issue)

Requires: pip install anthropic

# Parse + Claude analysis (downloads PDB automatically for known versions)
ANTHROPIC_API_KEY=... GITHUB_TOKEN=... \
  python3 .claude/skills/crash-analysis/analyze-crash.py \
    --dump file.dmp --version 0.4.6

# Also create a Linear issue
ANTHROPIC_API_KEY=... GITHUB_TOKEN=... LINEAR_API_KEY=... LINEAR_TEAM_ID=... \
  python3 .claude/skills/crash-analysis/analyze-crash.py \
    --dump file.dmp --version 0.4.6 --create-issue

# With a local PDB (skips download)
ANTHROPIC_API_KEY=... \
  python3 .claude/skills/crash-analysis/analyze-crash.py \
    --dump file.dmp --pdb MAGDA.pdb

Reading the output

Field	What to look for
Exception code	0xC0000005 = access violation (most common)
AV address	0x0 = null deref; 0xFFFFFFFFFFFFFFFF = sentinel/corruption
Rcx register	In x64, this is this — garbage here means the object is corrupt/freed
Stack scan	MAGDA.exe offsets narrow the subsystem; with PDB they resolve to function names

Common Windows crash patterns

Pattern	Likely cause
AV read at 0x0	Null pointer dereference
AV read at 0xFFFFFFFFFFFFFFFF	Dangling std::list iterator or sentinel value used as pointer
Rcx = ASCII/UTF bytes	String buffer being used as this pointer — memory corruption or bad cast
Rbp = small integer (0, 1, 2)	Stack frame pointer corrupted — look for buffer overflows
Crash on project reopen	Serialization/deserialization bug, often with non-ASCII paths on Windows