code-flow-tracer

A code-reading aid that follows how a feature, function, or piece of data moves through a project. It shows the calls, entry points, outside-system boundaries, and loops it finds.

In plain words
What is it for?
Use it to trace login, checkout, form submission, error handling, or the source of a value, and to see which functions call or are called by another function.
Why use it?
It removes the need to manually open many files and guess how parts of a codebase connect. This helps explain what happens after an action and where data comes from.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/lis186/sourceatlas/code-flow-tracer
Any agent
npx skills add lis186/SourceAtlas --skill code-flow-tracer
Clone the repo
git clone --depth 1 https://github.com/lis186/SourceAtlas

Made for: Claude Code, Codex.

Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 348 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00050 $0.00348
Opus 5 $0.00025 $0.00174
Sonnet 5 $0.00010 $0.00070
Haiku 4.5 $0.00005 $0.00035

Measured 2d ago against content hash 2264d48604af, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-flow-tracer 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 2d 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.

plugin/skills/code-flow-tracer/SKILL.md · 46 lines

What it actually says

Code Flow Tracer

When to Use

Trigger this skill when the user:

  • Wants to understand how a feature works end-to-end
  • Asks what happens when an action is triggered
  • Needs to trace data flow through the system
  • Asks "how does X work"
  • Asks "what calls X" or "what does X call"

Instructions

  1. Identify the feature, function, or flow the user wants to trace
  2. Run /sourceatlas:flow "<query>" with a natural language description
  3. Returns call graph, boundary detection, and flow visualization

Query Formats

  • Feature flow: /sourceatlas:flow "user login"
  • Function trace: /sourceatlas:flow "handleSubmit"
  • Error paths: /sourceatlas:flow "error handling flow"
  • Data origin: /sourceatlas:flow "where does userProfile come from"
  • Reverse trace: /sourceatlas:flow "who calls validateToken"

What User Gets

  • Call graph visualization (ASCII tree)
  • Boundary detection (API, DB, LIB, CLOUD markers)
  • Recursion and cycle detection
  • Entry points identification
  • 11 analysis modes available

Example Triggers

  • "How does the login flow work?"
  • "What happens when user clicks submit?"
  • "Trace the checkout process"
  • "Where does this data come from?"
  • "Who calls this function?"
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. 2d ago First seen · 46 lines · 50 tokens per session scan A 2264d48604af

Subscribe to this mod's changes

code-flow-tracer is a skill published in the GitHub repository lis186/SourceAtlas (47 stars, last pushed 1mo ago), licensed MIT. It adds 50 tokens to every session and 348 once invoked, about $0.0003 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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