The Art of Debugging
stas00/the-art-of-debugging
Condensed debugging method and tool recipes for Unix, Python and PyTorch programs: crashes, hangs, segfaults, wrong output, CUDA OOM, NaN values and slowness.
Find the root cause of Elixir/Phoenix bugs — crashes, exceptions, stack traces, compile errors, LiveView that won't update, silent failures.
Install Investigate
$ npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install oliver-kriska/claude-elixir-phoenix investigate --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/elixir-phoenix/skills/investigate .claude/skills/investigate && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "investigate" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigate into .claude/skills/investigate/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "investigate", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigateType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install oliver-kriska/claude-elixir-phoenix investigate --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/elixir-phoenix/skills/investigate .agents/skills/investigate && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "investigate" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigate into .agents/skills/investigate/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "investigate", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install oliver-kriska/claude-elixir-phoenix investigate --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/elixir-phoenix/skills/investigate .cursor/skills/investigate && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "investigate" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigate into .cursor/skills/investigate/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "investigate", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/oliver-kriska/claude-elixir-phoenix.git --path plugins/elixir-phoenix/skills/investigate--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install oliver-kriska/claude-elixir-phoenix investigate --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/elixir-phoenix/skills/investigate .gemini/skills/investigate && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "investigate" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigate into .gemini/skills/investigate/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "investigate", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install oliver-kriska/claude-elixir-phoenix investigateInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/elixir-phoenix/skills/investigate .github/skills/investigate && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "investigate" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigate into .github/skills/investigate/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "investigate", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install oliver-kriska/claude-elixir-phoenix investigate --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/elixir-phoenix/skills/investigate .opencode/skills/investigate && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "investigate" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins/elixir-phoenix/skills/investigate into .opencode/skills/investigate/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "investigate", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
investigate- GitHub stars
- 565
- Token cost
- ~1.4k tokens
- SKILL.md length
- 657 words
- Files
- 4 (incl. references)
- Skills in repo
- 109
- Repo updated
- First seen
- Licence
- MIT
At a glance
Find the root cause of Elixir/Phoenix bugs — crashes, exceptions, stack traces, compile errors, LiveView that won't update, silent failures.
- Works in 8 steps: Consult Compound Docs → Sanity Checks → Reproduce → …
- Something is broken
- SKILL.md covers Usage, Arguments, Mode Selection and Iron Laws, plus 3 more sections
- Calls claude
What it does
Investigate is an agent skill from oliver-kriska/claude-elixir-phoenix. Find the root cause of Elixir/Phoenix bugs — crashes, exceptions, stack traces, compile errors, LiveView that won't update, silent failures. Use when something is broken or misbehaves. --parallel for 4 tracks.
Its SKILL.md is about 1.4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files, including reference files (for example `references/debug-commands.md`, `references/error-patterns.md` and `references/investigation-template.md`).
It sits in Development, covering LLM observability, Root cause analysis and Debugging. It works with Elixir. The repository describes itself as: Claude Code plugin for Elixir/Phoenix/LiveView — 26 specialist agents, Iron Laws enforcement, and Tidewave MCP integration. Plan features with parallel research agents, execute… The licence is MIT.
When your agent uses it
- Something is broken
- Tasks that involve LLM observability
- Tasks that involve Root cause analysis
Example prompts
- “/investigate”
Workflow steps
8 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit 9767a82. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
claude
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Investigate loads about 1.4k tokens when it runs, and up to ~2.4k if it reads all its reference files. Until then it costs about 55 tokens; SKILL.md has 657 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from oliver-kriska/claude-elixir-phoenix at commit 9767a82, republished under its MIT licence (© oliver-kriska). 657 words, ~1,400 tokens.
Download SKILL.mdSave it as
.claude/skills/investigate/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.- name
- investigate
- description
- Find the root cause of Elixir/Phoenix bugs — crashes, exceptions, stack traces, compile errors, LiveView that won't update, silent failures. Use when something is broken or misbehaves. --parallel for 4 tracks.
- effort
- high
- argument-hint
- <bug description> [--parallel]
Investigate Bug
Investigate bugs using the Ralph Wiggum approach: check the obvious, read errors literally.
Usage
/phx:investigate Users can't log in after password reset
/phx:investigate FunctionClauseError in UserController.show
/phx:investigate Complex auth bug --parallelArguments
$ARGUMENTS = Bug description or error message. Add --parallel
for deep 4-track investigation.
Mode Selection
Use parallel mode (spawn deep-bug-investigator) when:
bug mentions 3+ modules, spans multiple contexts, is intermittent
or involves concurrency, or user says --parallel/deep.
Before spawning it, determine the effective maximum nesting depth. Use an
explicit positive-integer CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH value first;
when it is unset, inspect claude --version (the default is 1 in 2.1.217–2.1.218
and 3 in 2.1.219+). If the version is unavailable, conservatively use 1. At
depth 3+, use the deep-bug-investigator orchestrator. At depth 1 or 2, keep
orchestration in this main session: spawn the four
focused tracks (reproduction, root cause, impact, fix strategy) directly in
one parallel batch, wait for all four, then synthesize their evidence. Never
spawn an orchestrator that cannot delegate.
Otherwise: Run the sequential workflow below.
Avoid confirmatory subagents: once Steps 3-4 identify the root cause with high confidence, present it directly — four subagents (~80K tokens) re-verifying a finding already made in this context add cost, not evidence.
Iron Laws
- Read the error message literally first — Most bugs tell you exactly what's wrong; resist the urge to theorize before reading what the system is saying
- Check the obvious before going deep — Compile errors, missing migrations, atom/string mismatches explain 80% of bugs; exhausting the Ralph Wiggum checklist saves hours
- Check changeset errors before UI debugging — Silent form saves are almost always
{:error, changeset}with validation failures, not viewport or JS issues - Consult compound docs before investigating fresh — A previously solved problem saves the entire investigation cycle; always search
.claude/solutions/first - NEVER guess at a fix before reproducing — Reproduce first, then identify root cause, then fix. Skipping steps causes wrong fixes
- DO NOT apply a fix without confirming root cause — Verify your hypothesis with evidence (logs, tests, IO.inspect) before changing code
Investigation Workflow
Step 0: Consult Compound Docs
Search .claude/solutions/ for relevant keywords using Grep.
If matching solution exists, present it and ask: "Apply this fix, or investigate fresh?"
Show full SKILL.md (311 more words)Show less
Step 0a: Runtime Auto-Capture (Tidewave -- PRIMARY when available)
If Tidewave MCP is detected, start here instead of asking the user to paste errors. Auto-capture runtime context:
mcp__tidewave__get_logs level: :error-- capture recent errors- Parse stacktraces, correlate with source via
mcp__tidewave__get_source_location - For data bugs:
mcp__tidewave__execute_sql_queryto inspect state - For logic bugs:
mcp__tidewave__project_evalto test hypotheses - For UI bugs:
mcp__tidewave__get_source_locationwith component name
Present pre-populated context to the user:
Auto-captured from runtime:
- Error: {parsed error from logs}
- Location: {file:line from get_source_location}
Investigating this. Correct if wrong.
This eliminates copy-pasting errors between app and agent. If Tidewave NOT available: Fall through to Step 1.
Step 1: Sanity Checks
Run mix compile --warnings-as-errors 2>&1 | head -50, then mix ecto.migrations
(lists pending migrations without running them — ask before migrating).
Step 2: Reproduce
Run mix test test/path_test.exs --trace. Then read the last 200 lines of log/dev.log and search for "error" or "exception" patterns.
Step 3: Read Error LITERALLY
Parse the error message — check ${CLAUDE_SKILL_DIR}/references/error-patterns.md.
Step 4: Check the Obvious (Ralph Wiggum Checklist)
File saved? Atom vs string? Data preloaded? Pattern match correct? Nil? Return value? Server restarted?
LiveView form saves silently failing? Check changeset errors
FIRST — not viewport, click mechanics, or JS. A missing
hidden_input for a required embedded field causes {:error, changeset} with no visible UI feedback.
Step 5: IO.inspect / Tidewave project_eval
Step 6: Identify Root Cause
Find what's actually happening vs what should happen.
Step 7: Hand Off
Present root cause + evidence. Then route by fix size:
- Small, contained fix → offer to apply directly or via
/phx:quick - Multi-file or risky fix → suggest
/phx:plan {root cause summary}so the fix gets task structure and review - Non-obvious root cause → after the fix lands, suggest
/phx:compound
Autonomous Iteration
Use /ralph-loop:ralph-loop for autonomous debugging with
clear completion criteria and --max-iterations.
References
${CLAUDE_SKILL_DIR}/references/error-patterns.md— Common errors and checklist${CLAUDE_SKILL_DIR}/references/investigation-template.md— Output format${CLAUDE_SKILL_DIR}/references/debug-commands.md— Debug commands and common fixes
© oliver-kriska, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 3 other files (references) in plugins/elixir-phoenix/skills/investigate of oliver-kriska/claude-elixir-phoenix.
- SKILL.md
- references/debug-commands.md
- references/error-patterns.md
- references/investigation-template.md
Open the folder on GitHubat commit 9767a82
Compare with similar skills
Investigate next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Investigate this skilloliver-kriska/claude-elixir-phoenix | 565 | — | ~1.4k | Automated safety check: Pass | MIT | |
| The Art of Debuggingstas00/the-art-of-debugging | 1.7k | — | ~6.1k | Automated safety check: Notes | CC-BY-SA-4.0 | |
| Veomni DebugByteDance-Seed/VeOmni | 2.2k | — | ~2.8k | Automated safety check: Pass | Apache-2.0 | |
| Elixirstreamband/hydra-srt | 147 | — | ~804 | Automated safety check: Pass | Apache-2.0 | |
| Telemetry AnalyzerIBM/ibm-watsonx-orchestrate-adk | 178 | — | ~10k | Automated safety check: Notes | MIT | |
| Change CleanupSimon-Initiative/oli-torus | 119 | — | ~3.7k | Automated safety check: Pass | MIT |
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- Official
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Related
Works with
Categories
Questions about Investigate
What does Investigate do?
Find the root cause of Elixir/Phoenix bugs — crashes, exceptions, stack traces, compile errors, LiveView that won't update, silent failures. Investigate is an agent skill from oliver-kriska/claude-elixir-phoenix. Find the root cause of Elixir/Phoenix bugs — crashes, exceptions, stack traces, compile errors, LiveView that won't update, silent failures.
When should I use Investigate?
Investigate fits situations like: something is broken; tasks that involve LLM observability; tasks that involve Root cause analysis.
How do I install Investigate in Claude Code?
Run `npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a claude-code`. Or copy the skill folder (plugins/elixir-phoenix/skills/investigate in oliver-kriska/claude-elixir-phoenix) into .claude/skills/investigate in your project. Claude Code loads it when a task matches its description.
How do I install Investigate in Codex?
Run `npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a codex`. Or copy the skill folder (plugins/elixir-phoenix/skills/investigate in oliver-kriska/claude-elixir-phoenix) into .agents/skills/investigate in your project. Codex loads it when a task matches its description.
Can I use Investigate in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add oliver-kriska/claude-elixir-phoenix --skill investigate -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/investigate, .gemini/skills/investigate, .github/skills/investigate and .opencode/skills/investigate in your project.
What does Investigate need to run?
Going by SKILL.md and its folder, Investigate needs the command-line tools its instructions call (claude).
Does Investigate access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Investigate safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Investigate use?
Investigate is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Investigate use?
About 1.4k tokens (SKILL.md is roughly 5.6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1k tokens, read only when the agent opens those files.
What are the alternatives to Investigate?
Skills that share tags, products or a category with Investigate: The Art of Debugging (stas00/the-art-of-debugging, 1.7k stars), Veomni Debug (ByteDance-Seed/VeOmni, 2.2k stars), Elixir (streamband/hydra-srt, 147 stars) and Telemetry Analyzer (IBM/ibm-watsonx-orchestrate-adk, 178 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Investigate?
oliver-kriska (a GitHub user) maintains it in oliver-kriska/claude-elixir-phoenix, which has 565 GitHub stars. The repository holds 109 skills in this directory. The repository was last updated on October 5, 2026.
Source: oliver-kriska/claude-elixir-phoenix on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.