htmlspec

A self-contained HTML engineering plan saved as a file that can be opened in a web browser. It describes how to build a feature and can include diagrams, tables, decision trees, and interactive elements made with HTML, CSS, SVG, and JavaScript.

In plain words
What is it for?
Use it to document implementation choices, phases, dependencies, comparisons, and technical workflows before coding.
Why use it?
It gives developers a richer, easier-to-browse plan than plain text while keeping everything in one file and requiring no generated images.

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/disler/pi-agent-observability/htmlspec
Any agent
npx skills add disler/pi-agent-observability --skill htmlspec
Clone the repo
git clone --depth 1 https://github.com/disler/pi-agent-observability

Made for: Claude Code, Codex.

Per session 123 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,115 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 $0.00123 $0.03115
Opus 5 $0.00062 $0.01558
Sonnet 5 $0.00025 $0.00623
Haiku 4.5 $0.00012 $0.00312

Measured 3d ago against content hash 4d9687c985e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

htmlspec 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 3d 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.

.claude/skills/htmlspec/SKILL.md · 243 lines

How it starts

The opening of the file, as written. The whole thing — 243 lines — stays where its author put it; the contents beside it link to each section on GitHub.

htmlspec

Purpose

Produce an engineering implementation plan as one self-contained, text-only HTML pagespecs/<plan-name>.html — that you can open directly in a browser. Unlike a markdown spec, the plan is authored directly in HTML using the template below, and a dedicated Freeform zone lets you author any HTML you want (interactive toggles, animated SVG flows, comparison matrices, decision trees, etc.) to make the plan clearer and richer than prose could. No images are generated — all visual enrichment comes from inline HTML, CSS, SVG, and JS authored directly into the page.

Phases, in order:

  1. Plan phase — analyze, explore, design (same thinking as a normal spec).
  2. HTML authoring phase — write the plan into the HTML Plan Template.
  3. Freeform phase — enrich the page with custom HTML per the Freeform Instruction Set.

Variables

USER_PROMPT: $1 ALL_ARGUMENTS: $ARGUMENTS PLAN_OUTPUT_DIRECTORY: specs/ PLAN_SLUG: kebab-case name derived from the plan topic (e.g. in-memory-ttl-lru-cache) HTML_OUTPUT: specs/htmlspec-<PLAN_SLUG>.htmlthe filename MUST always begin with the htmlspec- prefix

Instructions

Plan phase

  • IMPORTANT: If no USER_PROMPT is provided, stop and ask the user to provide it.
  • Carefully analyze the USER_PROMPT. Determine task type (chore|feature|refactor|fix|enhancement) and complexity (simple|medium|complex).
  • Think deeply (ultrathink) about the best implementation approach.
  • Explore the codebase to understand existing patterns and architecture.
  • Decide which sections from the HTML Plan Template apply (include the conditional sections only when task type/complexity warrants them, exactly like a normal spec).
  • Generate a descriptive kebab-case PLAN_SLUG from the topic.

HTML authoring phase

  • Author the plan directly in HTML using the HTML Plan Template below — do not write a markdown file. The output is a single specs/htmlspec-<PLAN_SLUG>.html.
  • Keep the page self-contained: all CSS inline in <style>, any JS inline in <script>, no external network/CDN dependencies unless genuinely required (and if so, note it in Notes).
  • Fill every applicable section with real, detailed content — the plan must be implementable by another developer. Use semantic HTML: <ul>/<ol> for lists, <table> for comparisons, <pre><code> for code/commands.
  • Preserve the dark visual theme defined by the template's CSS tokens so the page reads as one body of work.
  • Do not include any <figure>/<img> elements — this skill is text-only.

Read the full file on GitHub · 243 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. 3d ago First seen · 243 lines · 123 tokens per session scan A 4d9687c985e5

Subscribe to this mod's changes

htmlspec is a skill published in the GitHub repository disler/pi-agent-observability (142 stars, last pushed 3mo ago), licensed MIT. It adds 123 tokens to every session and 3,115 once invoked, about $0.0006 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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