Panama/skills/diagnose-crash/SKILL.md

name, description

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description

diagnose-crash

Diagnose why a program crashed on this Panama machine, from a systemd-coredump core dump. Use when a process has segfaulted, aborted, or otherwise dumped core, when asked why an application crashed or disappeared, when launched by panama-agent-crash, or when a "stopped unexpectedly" desktop notification is acted on. Triggers: crash, segfault, SIGSEGV, SIGABRT, core dump, coredumpctl, "why did X crash", "X keeps crashing", backtrace symbolization.

Diagnosing a Crash

Work from evidence. The goal is an honest account of what happened, not a plausible-sounding story.

Establish the facts

coredumpctl info <pid> is the starting point. Beyond the backtrace, note the command line the process was started with — it usually reveals what the program was working on when it died, which is often the whole answer.

coredumpctl list shows whether this crash is a one-off or a pattern. Repeated crashes of the same program, or several programs dying together, point somewhere different than a single failure does. On this machine, Panama's System Health page keeps a crash count too — panama doctor check desktop.portal-stability knows whether the portal backend has been dying, which it chronically does.

Rule out the boring causes first

Check resource exhaustion before blaming the program: free -h, and the journal for OOM kills. A process killed by the OOM killer is not a bug in that process.

Correlate against the timeline

The crash timestamp is the most underused piece of evidence. Compare it against:

• Filesystem mtimes. A file whose mtime lands on the same second as the crash strongly suggests what triggered it.
• The journal around that moment, for related warnings from the same or neighbouring processes.
• Recent package updates. rpm -qa --last | head — a crash that starts right after an update points at the update. dnf history shows what a recent transaction actually changed.

Read the whole core, not just frame 0

Thread stacks other than the crashing one show what work was in flight. That context often explains the trigger even when the crashing frame itself cannot be symbolized. Note any third-party code in the address space — extensions, plugins, out-of-tree drivers — but do not pin blame on it without evidence that it is actually implicated.

Symbolize when you can

This is Fedora, which runs a public debuginfod server:

core=$(mktemp -t crash-XXXXXX.core)
trap 'rm -f "$core"' EXIT
coredumpctl dump <pid> --output="$core"
DEBUGINFOD_URLS="https://debuginfod.fedoraproject.org/" \
  gdb -q <executable> "$core" \
  -batch -ex 'set debuginfod enabled on' -ex 'bt'

A core is a verbatim copy of the process's memory and can hold passwords, tokens, and private documents. Write it to a fresh mktemp path rather than a predictable shared one, and delete it when you are done — never leave it in /tmp.

Many packages publish no debug symbols. When frames stay unresolved, say so — never invent function names to fill the gap. An unsymbolized stack still has shape: which library each frame belongs to, and whether the crash came from a signal handler, a main loop, or a worker thread.

Report

1. What crashed, and what it was doing at the time.
2. The most likely mechanism — separating clearly what the evidence proves from what you are inferring.
3. Whether any user data was lost, and where it can be recovered from. Check the trash before concluding anything is gone.
4. Whether it is likely to recur, and what would avoid or fix it.

Be straight about the limits of the evidence. If the cause is genuinely ambiguous, say so rather than assembling confidence out of guesswork.

Leave the system as you found it. Diagnosis reads; it does not fix, tidy, or reconfigure. The one thing to clean up is your own: delete the core you extracted above. If the user wants the fix applied, that is a second, explicitly requested step — and anything needing root goes through panama-sudo --reason (load the panama-sudo skill).

If the crash is Panama's

The shell, the compositor config, and everything under ~/.local/share/Panama are the user's own repository — a crash there is fixable in place, not an upstream report. Load the panama skill before touching the repo: it carries the live-desktop rules that keep an investigation from becoming a second outage.