session-preflight

session-preflight is a cursor rule for coding agents from caioribeiroclw-pixel/pluribus. It costs 184 tokens per session, scanned A, original, MIT.

A session-start rule for coding agents that requires a visible check before they change files, run commands, or use external services. The check records required context, permission mode, and whether the work can proceed.

In plain words
What is it for?
Use it to control agent sessions in repositories or other projects where edits and external actions must wait until files such as AGENTS.md or project rules have been checked.
Why use it?
It prevents an agent from making changes before it has checked important project instructions and operating conditions. If those checks are unavailable, it keeps the session read-only and asks for the missing information.

Cursor rule

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 rules/caioribeiroclw-pixel/pluribus/session-preflight
Clone the repo
git clone --depth 1 https://github.com/caioribeiroclw-pixel/pluribus

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 session-preflight

README.md
[![agentmods](https://agentmods.dev/badge/rules/caioribeiroclw-pixel/pluribus/session-preflight.svg)](https://agentmods.dev/rules/caioribeiroclw-pixel/pluribus/session-preflight)
Your own site
<a href="https://agentmods.dev/rules/caioribeiroclw-pixel/pluribus/session-preflight"><img src="https://agentmods.dev/badge/rules/caioribeiroclw-pixel/pluribus/session-preflight.svg" alt="Measured on agentmods" height="20"></a>
Per session 184 This file is loaded in full into every session.
When invoked 184 The same file — it is already loaded in full.
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 5.1 $0.00184 $0.00184
Opus 5 $0.00092 $0.00092
Sonnet 5 $0.00037 $0.00037
Haiku 4.5 $0.00018 $0.00018

Measured 5d ago against content hash d241b18ccf3f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

session-preflight 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 5d 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.

examples/session-preflight-receipts/session-preflight.mdc · 19 lines

What it actually says

Before using Shell, Write, Apply Patch, or external MCP tools, produce a session preflight receipt.

The receipt must state:

  • required first step: session_guard.session_init or the local equivalent
  • required context files checked, such as MEMORY.md, AGENTS.md, .cursor/rules/*.mdc, or CLAUDE.md
  • whether only read-only tools are allowed before preflight
  • proceed mode: read_only, read_then_patch, stop, or ask_human
  • reason for the mode

Do not paste raw memory or secrets into the receipt. Use status and non-secret fingerprints instead.

If the preflight is missing or required context is unavailable, stay in read_only mode and ask for the missing context before edits.

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. 5d ago First seen · 19 lines · 184 tokens per session scan A d241b18ccf3f

Subscribe to this mod's changes

session-preflight is a cursor rule published in the GitHub repository caioribeiroclw-pixel/pluribus (13 stars, last pushed 1mo ago), licensed MIT. It adds 184 tokens to every session, about $0.0009 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.