footnotes

A way to add clickable footnotes to Markdown files and Jupyter notebooks, including references and notes. It uses links and HTML anchors that work in JupyterLab, GitHub, and standard Markdown viewers.

In plain words
What is it for?
Use it when adding citations, evidence references, notes, or footnotes to notebooks and Markdown documents.
Why use it?
It avoids footnote syntax that Jupyter notebooks do not support reliably. Readers can jump from a reference marker to its matching note or evidence path.

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/stellarshenson/claude-code-plugins/footnotes
Any agent
npx skills add stellarshenson/claude-code-plugins --skill footnotes
Clone the repo
git clone --depth 1 https://github.com/stellarshenson/claude-code-plugins

Made for: Claude Code, Codex.

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 842 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 $0.00054 $0.00842
Opus 5 $0.00027 $0.00421
Sonnet 5 $0.00011 $0.00168
Haiku 4.5 $0.00005 $0.00084

Measured 2d ago against content hash b5c78d9aff31, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

footnotes 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.

plugins/datascience/skills/footnotes/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Footnotes in Markdown

Standard [^1] footnotes unsupported in Jupyter. Use HTML anchor pattern. Proven in JupyterLab (incl. id sanitizer), GitHub, standard markdown.

How it works in JupyterLab

  1. Markdown writes <span id="D005">
  2. JupyterLab sanitizer renames id to data-jupyter-id="D005" (not deleted)
  3. User clicks blue superscript link [<sup>D005</sup>](#D005)
  4. JupyterLab click handler matches #D005 against data-jupyter-id="D005"
  5. Calls scrollIntoView() on target

Pattern

Inline reference (clickable superscript):

- dowód: [<sup>D005</sup>](#D005) dowody/03 komunikacja z matką/2023-09-06 pismo.pdf

Renders: clickable blue superscript D005 + file path.

Target anchor (references section):

- <span id="D005">D005 `dowody/03 komunikacja z matką/2023-09-06 pismo.pdf`</span>

Renders: bullet with D005 label + monospace path.

Requirements

  • Target MUST use <span id="...">. Not <div>, not heading
  • Inline link MUST use (#DXXX) hash. Not relative path
  • No <br> between entries - bullets handle spacing
  • <sup> inside link optional. NOT inside target span
  • IDs unique across document

Numbering Schemes

Context Pattern Example
Evidence/documents D001, D002 [<sup>D005</sup>](#D005)
General footnotes fn1, fn2 [<sup>1</sup>](#fn1)
Paper citations ref1, ref2 [<sup>ref3</sup>](#ref3)
Named references fn_dataset, fn_paper [<sup>*</sup>](#fn_dataset)

Full Example

## Timeline

- **2023-01-15 - Author submits proposal to committee**
  - source: email
  - evidence: [<sup>D001</sup>](#D001) documents/2023-01-15 proposal submission.pdf
  - category: Submissions

- **2023-02-20 - Committee responds with revision request**
  - source: letter
  - evidence: [<sup>D002</sup>](#D002) documents/2023-02-20 revision request.pdf
  - category: Responses

---

## References

- <span id="D001">D001 `documents/2023-01-15 proposal submission.pdf`</span>
- <span id="D002">D002 `documents/2023-02-20 revision request.pdf`</span>

Read the full file on GitHub · 87 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 · 87 lines · 54 tokens per session scan A b5c78d9aff31

Subscribe to this mod's changes

footnotes is a skill published in the GitHub repository stellarshenson/claude-code-plugins (3 stars, last pushed 3d ago), licensed MIT. It adds 54 tokens to every session and 842 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.

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