trace

trace is a skill for Claude Code from oliver-kriska/claude-elixir-phoenix. It costs 33 tokens per session (782 once invoked), scanned A, original, MIT.

A guide for tracing how Elixir functions are reached from application entry points. A call tree shows the chain of functions leading from places such as controllers or background jobs to a target function.

In plain words
What is it for?
Use it to investigate data flow, incomplete stack traces, unexpected values, or the impact of changing a function's arguments.
Why use it?
It helps explain where a value or bug comes from and shows all callers before a function is changed.

Skill for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: mentions subagents.

Part of the phx plugin — 50 skills, 26 agents, 10 hooks shipped together

Good fit Use it to investigate data flow, incomplete stack traces, unexpected values, or the impact of changing a function's arguments.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/oliver-kriska/claude-elixir-phoenix/trace
Install

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.

Any agent
npx skills add oliver-kriska/claude-elixir-phoenix --skill trace
Clone the repo
git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix

Made for: Claude Code.

Or install phx, the plugin that ships this one along with the rest of its 50 skills, 26 agents, 10 hooks.

Wrote 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.

agentmods badge for trace

README.md
[![agentmods](https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/trace.svg)](https://agentmods.dev/skills/oliver-kriska/claude-elixir-phoenix/trace)
Your own site
<a href="https://agentmods.dev/skills/oliver-kriska/claude-elixir-phoenix/trace"><img src="https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/trace.svg" alt="Measured on agentmods" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 782 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00033 $0.00782
Opus 5 $0.00016 $0.00391
Sonnet 5 $0.00007 $0.00156
Haiku 4.5 $0.00003 $0.00078

Measured 4d ago against content hash d98db05ed2e8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

trace 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.

plugins/elixir-phoenix/skills/trace/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Call Tracing

Build call trees showing how functions are reached from entry points.

Iron Laws - Never Violate These

  1. Always use mix xref callers first - It's authoritative; grep is fallback only
  2. Stop at entry points - Controllers, LiveView callbacks, Oban workers, GenServer callbacks
  3. Track visited MFAs - Prevent infinite loops from circular calls
  4. Extract argument patterns - Just knowing "who calls" isn't enough; HOW they call matters
  5. Max depth 10 - Deeper trees indicate architectural issues, not useful traces

When to Build Call Tree (Use Proactively)

Condition Why Call Tree Helps
Unexpected nil/value at runtime Trace where the value originates
Bug can't reproduce locally See all entry points that reach the code
Changing function signature Find all callers and their argument patterns
Incomplete stack trace Get full path context
"Where does X come from?" Visual answer to data flow question

Quick Trace

Run the caller query first, then inspect another function in the chain as needed:

mix xref callers MyApp.Accounts.update_user/2
mix xref callers MyApp.Accounts.get_user/1

Read the reported locations to see argument patterns.

Entry Points (Stop Here)

Pattern Type
def mount/3, def handle_event/3 LiveView
def index/2, def show/2, def create/2 Controller
def perform(%Oban.Job{}) Oban Worker
def handle_call/3, def handle_cast/2 GenServer

Delegate to call-tracer Agent

For full recursive tree with argument extraction and parallel category tracing:

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 2+, delegate to the orchestrator below. At depth 1, keep orchestration in this main session: spawn the applicable controller, LiveView, worker, and internal tracing prompts directly, then merge their results. Never spawn an orchestrator that cannot delegate.

Read the full file on GitHub · 86 lines

Files

What ships with it

3 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.

Changes

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.

  1. 4d ago First seen · 86 lines · 33 tokens per session scan A d98db05ed2e8

Subscribe to this mod's changes

trace is a skill published in the GitHub repository oliver-kriska/claude-elixir-phoenix (539 stars, last pushed 2d ago), licensed MIT. It adds 33 tokens to every session and 782 once invoked, about $0.0002 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 2026-09-03.

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