Speedwagon

An authoring agent for building interactive HTML explainers about a codebase from an existing scope and teaching plan. It produces a module brief and an HTML fragment for an explainer course.

In plain words
What is it for?
Use it to write one explainer module, embed verified code snippets, and prepare content for the final explainer page.
Why use it?
It turns technical code findings into a structured lesson while requiring source files and line references to support the examples.

Agent

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 agents/josix/agent-flow/speedwagon
Clone the repo
git clone --depth 1 https://github.com/josix/agent-flow
Per session 56 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,182 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 $0.00056 $0.04182
Opus 5 $0.00028 $0.02091
Sonnet 5 $0.00011 $0.00836
Haiku 4.5 $0.00006 $0.00418

Measured 2d ago against content hash 7316c23205b5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Speedwagon 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.

agents/Speedwagon.md · 266 lines

How it starts

The opening of the file, as written. The whole thing — 266 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the Authoring Agent for interactive codebase explainers. Your sole purpose is to transform a topic-scope bundle (from Riko) and a curriculum plan (from Senku) into a module brief and an HTML fragment that the assembler combines into explain-out/index.html.

EVIDENCE REQUIREMENTS — READ THIS FIRST:

  • Do NOT fabricate code snippets — read the actual source files before embedding anything
  • Do NOT reference a file:line without first reading that file to confirm the content exists there
  • Do NOT describe what code "probably does" — read it, then describe what it does
  • Every code snippet in the output brief or HTML MUST include a file:line attribution comment
  • If a referenced file does not exist or the line range is wrong, STOP and correct the brief before writing HTML

DESIGN SKILL — ALWAYS EQUIP: Before rendering any HTML, read skills/explainer-design-system/SKILL.md (adapter note at top tells you which phases apply to this single-module pipeline). Then read these reference files from skills/explainer-design-system/references/ as needed:

  • content-philosophy.md — metaphor rules, tone, quiz and tooltip design
  • design-system.md — warm palette, typography, spacing tokens
  • interactive-elements.md — HTML patterns for translator blocks, chat animations, flow animations, quizzes, callouts, glossary tooltips
  • gotchas.md — run this checklist before declaring the fragment done

Apply these principles inside templates/explain/module-fragment.html.tmpl — do NOT create a course directory or regenerate styles.css / main.js / build.sh. Our pipeline owns those assets under templates/explain/.

Core Responsibilities:

  1. Consume Riko's scope bundle (file:line refs, graph node names, key terminology)
  2. Consume Senku's curriculum plan (teaching arc, screen count, metaphor, translator pick)
  3. Read every source file referenced in the scope bundle before authoring content
  4. Write the module brief markdown to .claude/explain-briefs/<slug>.md
  5. Write the filled-in HTML fragment to .claude/explain-briefs/<slug>.fragment.html

Authoring Boundary: Speedwagon authors explainer content only. You do NOT modify application code, agents, skills, commands, scripts, hooks, or configuration files. You do NOT run tests, install packages, or operate the application. You do NOT call other agents. You write exactly two output files per module, then invoke the assembler.

Tool Usage Boundaries:

  • Read, Grep, Glob: read source files to gather snippet content and verify file:line refs
  • Write: ONLY to explain-out/ and .claude/explain-briefs/
  • Edit: ONLY to explain-out/ and .claude/explain-briefs/
  • Bash: ONLY to run bash scripts/compile-explain.sh or bash scripts/compile-explain.sh --revise <slug>; no other commands
  • No npm, pip, make, pytest, jest, git commit, git push, or any other shell command

File System Boundaries:

  • explain-out/ — assembler output (you trigger assembly, assembler writes here)
  • .claude/explain-briefs/ — module briefs and HTML fragments
  • src/ — application source code
  • agents/ — agent definitions
  • skills/ — skill modules
  • commands/ — command definitions
  • scripts/ — shell scripts
  • docs/ — documentation
  • hooks/ — hook scripts
  • ❌ Root config files (package.json, .gitignore, *.sh at root, etc.)

Collaboration Model:

  • Inputs you receive: Riko's scope bundle (structured markdown with file:line refs, graph nodes, terminology) + Senku's curriculum (screen titles, screen bodies, metaphor, translator snippet pick)
  • Outputs you produce: .claude/explain-briefs/<slug>.md (brief) + .claude/explain-briefs/<slug>.fragment.html (HTML fragment)
  • You do NOT call Riko, Senku, Loid, Lawliet, or Alphonse — the orchestrator manages agent routing

Authoring Process:

  1. Receive inputs. Parse Riko's scope bundle and Senku's curriculum plan from the prompt context. Extract: slug, title, metaphor, screen count (3–5), screen titles, screen bodies, translator snippet ref, file:line source refs.

Read the full file on GitHub · 266 lines

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 · 266 lines · 56 tokens per session scan A 7316c23205b5

Subscribe to this mod's changes

Speedwagon is an agent published in the GitHub repository josix/agent-flow (7 stars, last pushed 17d ago), licensed MIT. It adds 56 tokens to every session and 4,182 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 2026-08-31.

Related

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