Why numbered ledger ids (grounding research basis)

Design notes for anyone changing the citation instructions or the ledger mechanics. The wording in SKILL.md is not arbitrary.

The structural trick

Hallucinated citations happen when a model reconstructs a URL from memory. If the only thing the model has to emit is a small integer it was handed at retrieval time, there is nothing to reconstruct — a wrong id is detectable (it's not in the ledger) and a wrong URL is impossible (the model never types one; render does). This is the property Perplexity's product relies on, and it's why the ledger, not the prose, owns the URL.

Consequence: register at retrieval, render mechanically. Any workflow that lets the model type a URL into the Sources block gives the guarantee back.

Cite while writing, not after

ALCE (arXiv:2305.14627) evaluates attribution for LLM answers and finds that generating citations during composition, from numbered retrieved snippets, produces materially better attribution than post-hoc citation insertion. Post-hoc attribution invites the model to find a source that plausibly matches a sentence it already wrote — which is exactly how a citation ends up supporting something the page doesn't say.

Hence: cite per supported sentence, in-line, as the sentence is written. Never a citation dump at the end of a paragraph or document.

Verbatim quotes ground claims

WebGPT (arXiv:2112.09332) collects verbatim quotes at browse time and composes answers from them. The practical rule for this skill: when a claim carries a figure, date, name, or quantity, take it from the source's own words rather than paraphrasing from a summary of a summary. Each summarization hop is a chance for a number to drift.

Formatting conventions

From Perplexity's leaked system prompts (jujumilk3/leaked-system-prompts) — the conventions are worth copying because they're the ones users have been trained to read:

• Marker directly after the terminal punctuation, no space: water.[1]
• Each id in its own brackets: [1][2], not [1, 2]
• At most 3 ids per sentence — beyond that the citation stops identifying which source carries the claim
• Never cite a source not actually consulted
• Query classes that shouldn't be cited (translation, creative writing, casual chat) are exempted by instruction, not by a separate classifier

Perplexity forbids raw URLs in the answer because its UI renders source cards. Hermes has no such UI layer in chat or in a written file, so this skill renders the id → URL list explicitly instead.

Related in-tree implementation

tools/web_tools.py grew an in-process version of this idea (a url -> [n] registry plus citation guidance attached to tool results) in PR #44833. That path grounds ad-hoc web answers automatically when it lands. This skill is the portable half: it works with any retrieval source (browser, curl, CLIs, local PDFs) and it persists the ledger to disk so multi-turn, multi-file, and multi-subagent work keeps stable ids. The two can coexist — the ledger is the source of truth for anything written to a file.