daylight-theory

daylight-theory is a skill for Claude Code, Codex from Kdevos12/ALKYL. It costs 67 tokens per session (615 once invoked), scanned A, original, MIT.

A guide to standard text formats and search rules for describing molecules and chemical reactions: SMILES, SMARTS, and SMIRKS, plus molecular fingerprints for similarity checks.

In plain words
What is it for?
It is for representing molecules, writing substructure searches, describing reaction changes, comparing fingerprints, and understanding chemical database searches.
Why use it?
It explains the notation behind many cheminformatics tools, making it easier to read, generate, search, and compare chemical structures correctly.

Skill for Claude CodeCodex

Part of the alkyl plugin — 27 skills shipped together

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/kdevos12/alkyl/daylight-theory
Any agent
npx skills add Kdevos12/ALKYL --skill daylight-theory
Clone the repo
git clone --depth 1 https://github.com/Kdevos12/ALKYL

Made for: Claude Code, Codex.

Or install alkyl, the plugin that ships this one along with the rest of its 27 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for daylight-theory

README.md
[![agentmods](https://agentmods.dev/badge/skills/kdevos12/alkyl/daylight-theory.svg)](https://agentmods.dev/skills/kdevos12/alkyl/daylight-theory)
Your own site
<a href="https://agentmods.dev/skills/kdevos12/alkyl/daylight-theory"><img src="https://agentmods.dev/badge/skills/kdevos12/alkyl/daylight-theory.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 615 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 $0.00067 $0.00615
Opus 5 $0.00034 $0.00308
Sonnet 5 $0.00013 $0.00123
Haiku 4.5 $0.00007 $0.00061

Measured 4d ago against content hash b2fe956c62d6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

daylight-theory 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 4d 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.

skills/daylight-theory/SKILL.md · 41 lines

How it starts

The opening of the file, as written. The whole thing — 41 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Daylight Theory — Cheminformatics Fundamentals

The Daylight Theory Manual is the canonical reference for the molecular languages underlying modern cheminformatics: SMILES, SMARTS, SMIRKS, and fingerprints. These are not Daylight-proprietary — they are industry-standard formats implemented in RDKit, OpenBabel, CDK, and every major cheminformatics toolkit.

Router — What to Read

Topic Reference
Molecular graph model, aromaticity, chirality, SSSR, reaction representation references/molecules.md
SMILES syntax: atoms, bonds, branches, rings, stereochemistry, reactions references/smiles.md
SMARTS query language: primitives, operators, recursive SMARTS, reaction queries references/smarts.md
SMIRKS reaction transforms: atom maps, grammar, stereochemistry references/smirks.md
Fingerprints: structural keys, path-based FP, folding, Tanimoto, Tversky, all similarity measures references/fingerprints.md
Chemical database concepts: hash tables, identifiers, in-memory search, pools, hitlists references/cheminformatics-databases.md

Core Languages at a Glance

Language Purpose Example
SMILES Encode a specific molecule CC(=O)Oc1ccccc1C(=O)O
SMARTS Describe a molecular pattern [OH]c1ccccc1 (phenol)
SMIRKS Encode a reaction transform [C:1][Br:2]>>[C:1][I:2]

Key Principles

  • Molecular graph: atoms = nodes, bonds = edges; properties are explicit or derived
  • Aromaticity: Hückel 4N+2 rule, all ring atoms sp² — a derived, not stored, property
  • SMILES organic subset: B, C, N, O, P, S, F, Cl, Br, I — no brackets needed at normal valence
  • SMARTS unspecified = unrestricted: O in SMARTS matches any aliphatic oxygen; in SMILES it means water
  • Tanimoto: c/(a+b+c) — the standard fingerprint similarity; double-zero independent
  • rdkit — implementation of these concepts in Python
  • scientific-skills:matchms — spectrum similarity (same mathematical ideas)

Read the full file on GitHub · 41 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 4d ago First seen · 41 lines · 0 tokens per session scan A b2fe956c62d6

Subscribe to this mod's changes

daylight-theory is a skill published in the GitHub repository Kdevos12/ALKYL (6 stars, last pushed 5mo ago), licensed MIT. It adds 67 tokens to every session and 615 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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