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 agentmods add skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-perfnpx skills add ccarvalho-eng/codex-elixir-phoenix --skill elixir-phoenix-perfgit 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-perf)<a href="https://agentmods.dev/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-perf"><img src="https://agentmods.dev/badge/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-perf.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 | $0.00026 | $0.01009 |
| Opus 5 | $0.00013 | $0.00504 |
| Sonnet 5 | $0.00005 | $0.00202 |
| Haiku 4.5 | $0.00003 | $0.00101 |
Grade A, and why
elixir-phoenix-perf 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 4d 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.
This is a copy
95% identical to perf — 32 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Performance Analysis
Analyze code for performance issues across Ecto, LiveView, and OTP layers. Prioritize findings by impact and effort.
Usage
`elixir-phoenix-perf` # Analyze full project
`elixir-phoenix-perf` lib/my_app/accounts.ex # Analyze specific module
`elixir-phoenix-perf` --focus ecto # Ecto queries only
`elixir-phoenix-perf` --focus liveview # LiveView memory only
`elixir-phoenix-perf` --focus otp # OTP bottlenecks only
Arguments
$ARGUMENTS = Optional module/context path and --focus flag.
Iron Laws
- MEASURE BEFORE OPTIMIZING — Never optimize without evidence of a problem
- DATABASE FIRST — 90% of Elixir performance issues are query-related
- ONE CHANGE AT A TIME — Isolate optimizations to measure impact
- NEVER benchmark in dev mode — Always use
MIX_ENV=prodfor performance measurements; dev mode includes code reloading, debug logging, and unoptimized compilation that invalidate results
Workflow
Step 1: Identify Scope
Check specific file if provided. Otherwise scan full project:
# Find hot paths: contexts, LiveViews, workers
find lib/ -name "*.ex" | head -50
Step 2: Run Analysis Tracks
Spawn analysis agents in parallel based on focus:
Ecto Track (default or --focus ecto):
Spawn elixir-phoenix:elixir-reviewer with prompt:
"Analyze for N+1 queries, missing preloads, unindexed queries,
and inefficient patterns. Check: Repo.all in loops,
Enum.map with Repo calls, missing preload, queries without
indexes on WHERE/JOIN columns."
LiveView Track (default or --focus liveview):
Spawn elixir-phoenix:elixir-reviewer with prompt:
"Analyze LiveViews for memory issues: large assigns, missing
streams for lists, assigns that grow unbounded, heavy
handle_info processing, missing assign_async for slow ops."
OTP Track (only with --focus otp):
Spawn elixir-phoenix:otp-advisor with prompt:
"Analyze for OTP bottlenecks: GenServer mailbox growth,
synchronous calls in hot paths, missing Task.async for
parallel work, ETS opportunities for read-heavy state."
What ships with it
2 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.
- 4d ago First seen · 125 lines · 26 tokens per session scan A 2cf42844d387
elixir-phoenix-perf is a skill published in the GitHub repository ccarvalho-eng/codex-elixir-phoenix (11 stars, last pushed 4mo ago), licensed MIT. It adds 26 tokens to every session and 1,009 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to perf, differing in 32 lines, and is treated as a copy.
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