What is prism CLAUDE.md?

Project instructions for Prism, a knowledge layer that observes Claude Code and Cursor work, turns repeated patterns into stored knowledge, and can share approved knowledge as team skills.

Use them when developing or modifying Prism so its hooks, SQLite storage, Markdown knowledge files, editor integrations, and team skill registry follow the project design.

They set the rules that keep observation in the background, store data in the intended files, and route AI calls through the supported editor command-line tools.

How ProsusAI/prism configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to ProsusAI/prism. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/ProsusAI/prism/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/ProsusAI/prism

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/prosusai/prism/claude-md/github.svg)](https://agentmods.dev/instructions/prosusai/prism/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/prosusai/prism/claude-md"><img src="https://agentmods.dev/badge/instructions/prosusai/prism/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/prosusai/prism/claude-md"><img src="https://agentmods.dev/badge/instructions/prosusai/prism/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 2,987 This file is loaded in full into every session.

When invoked 2,987 The same file — it is already loaded in full.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.02987	$0.02987
Opus 5.5	$0.01195	$0.01195
Sonnet 5.5	$0.00597	$0.00597
Haiku 4.5	$0.00299	$0.00299

Measured 2mo ago against content hash 5ed6d3e143f5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

prism CLAUDE.md scanned grade A with 1 finding 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 2mo 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

- **`subprocess.run()` not `os.system()`** — always use `capture_output=True, text=True, timeout=N`.

CLAUDE.md · 168 lines

How it starts

The opening of the file, as written. The whole thing — 168 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Project

Prism — knowledge layer for Claude Code and Cursor. Two things:

Personal learning: hooks observe tool usage, a two-phase extraction pipeline (fast model proposes, strong model validates — via claude or Cursor agent per backend) converts patterns into engrams (living, decaying knowledge). Engrams flow back into the IDE via context files (.claude/prism.md, .cursor/rules/prism.mdc) and MCP tools.
Team skills: high-confidence engrams promote to skills published to a Cloudflare Worker-backed registry that teams query.

Hard constraints

Hooks never block the IDE — capture.sh (Claude Code) and capture_cursor.sh (Cursor) must always exit 0; background spawns only.
Storage split — observations + sessions live in SQLite (~/.prism/prism.db) via stdlib sqlite3. Engrams stay flat Markdown + YAML frontmatter; the engram index stays index.json. No external DB, no ORM.
AI calls via IDE CLIs only — claude --print (Claude Code) or agent -p (Cursor). Never import the Anthropic SDK or cursor-sdk. No API keys for extraction. Routed through lib/agent_runner.py (resolve_backend + run_agent).
One extraction CLI per user — Claude-only needs claude login; Cursor-only needs agent login. Not both unless you use both IDEs.
Custom YAML frontmatter parser — never import PyYAML. Split on ---, parse key: value lines.
subprocess.run() not os.system() — always use capture_output=True, text=True, timeout=N.
MCP stdout is protocol-only — any stray print() in lib code corrupts the JSON-RPC stream. All logging to stderr.
Never read .env files — config comes from os.environ only. No dotenv parsing, no opening .env files.

Tech Stack

Layer	Technology	Notes
Library / CLI	Python 3.12+ (stdlib only)	`argparse`, `json`, `pathlib`, `subprocess`, `hashlib`, `fcntl`
Hooks / installer	Bash (POSIX-compatible)	`capture.sh` / `capture_cursor.sh` → `capture.py`. Avoid Bash 4+ features (macOS ships 3.2)
AI calls	`claude` CLI or Cursor `agent` CLI	Claude: `haiku` / `sonnet`. Cursor: `cursor_models.fast` / `cursor_models.strong` (defaults: `composer-2.5[fast=false]`, `claude-4.6-sonnet-medium`). All via `lib/agent_runner.py`.
MCP server	Python stdio, JSON-RPC 2.0	Protocol version `2025-03-26`. Tools only, no resources/prompts
Storage	SQLite (stdlib `sqlite3`) + flat files	`prism.db` = observations + sessions + `observations_fts` (FTS5); `index.json` = engram index; Markdown engrams
Registry API	Cloudflare Worker (TypeScript)	Wrangler 4.x, Node 22 LTS — for registry maintainers only, not end users
Registry backend	GitHub repo	Versioning, PRs, CI, and hosting for free. No database needed

Read the full file on GitHub · 168 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.

2mo ago First seen · 168 lines · 2,987 tokens per session scan A 5ed6d3e143f5

Subscribe to this mod's changes

prism CLAUDE.md is an instructions file published in the GitHub repository ProsusAI/prism (20 stars, last pushed 4mo ago), licensed Apache-2.0. It adds 2,987 tokens to every session, about $0.0119 per session on Opus 5.5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Memory and context

prism CLAUDE.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
prism CLAUDE.mdProsusAI/prism	Instructions file	20	4mo ago	Apache-2.0	A	2,987	Claude Code
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	yesterday	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

prism: Instructions file for Claude Code