Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ccarvalho-eng/codex-elixir-phoenix --skill elixir-phoenix-investigategit clone --depth 1 https://github.com/ccarvalho-eng/codex-elixir-phoenixWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-investigate)<a href="https://agentmods.dev/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-investigate"><img src="https://agentmods.dev/badge/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-investigate.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00023 | $0.01078 |
| Opus 5 | $0.00012 | $0.00539 |
| Sonnet 5 | $0.00005 | $0.00216 |
| Haiku 4.5 | $0.00002 | $0.00108 |
Grade A, and why
elixir-phoenix-investigate scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Investigate Bug
Investigate bugs using the Ralph Wiggum approach: check the obvious, read errors literally.
Usage
`elixir-phoenix-investigate` Users can't log in after password reset
`elixir-phoenix-investigate` FunctionClauseError in UserController.show
`elixir-phoenix-investigate` Complex auth bug --parallel
Arguments
$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.
Otherwise: Run the sequential workflow below.
Avoid confirmatory subagents: Do NOT spawn parallel subagents to "verify" findings you already identified in the main context. If Step 3-4 already identified the root cause with high confidence, present it directly — don't spend ~80K tokens on 4 subagents to confirm what's already obvious (confirmed waste: session c135330a).
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
.codex/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
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 7d ago First seen · 120 lines · 23 tokens per session scan A 0e3c81901c85
elixir-phoenix-investigate is a skill published in the GitHub repository ccarvalho-eng/codex-elixir-phoenix (11 stars, last pushed 4mo ago), licensed MIT. It adds 23 tokens to every session and 1,078 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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