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.
git clone --depth 1 https://github.com/jstxn/reinWrote 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.
[](https://agentmods.dev/rules/jstxn/rein/rein-plan)<a href="https://agentmods.dev/rules/jstxn/rein/rein-plan"><img src="https://agentmods.dev/badge/rules/jstxn/rein/rein-plan.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00031 | $0.00750 |
| Opus 5 | $0.00015 | $0.00375 |
| Sonnet 5 | $0.00006 | $0.00150 |
| Haiku 4.5 | $0.00003 | $0.00075 |
Grade A, and why
rein-plan 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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.
rein-plan
Use this after triage and before implementation when the work involves multiple files, multiple concerns, or a non-obvious execution order.
When To Use
- The task touches more than two files or modules
- The execution order matters (migrations before code, types before consumers)
- There are dependencies between subtasks
- The risk of a partial implementation is high
- A completed
rein-interviewspec bundle already exists and should drive the plan
When Not To Use
- The task is a single-file, single-concern change
- Triage already produced a clear, linear path
- The user explicitly asks to skip planning
Interview Handoff
Before planning, check whether there is a completed rein-interview artifact to consume.
Artifact priority:
- If the user provides
--from-interview <slug|path>, use that artifact. - If the user provides or references a
rein interview handoff --to planresult, use itssourceResultandrecommendedSkillInvocation. - Otherwise, look under
.rein/specs/forrein-interview-*/result.json. - If one clearly matches the current task, use it.
- If several plausible artifacts exist, prefer the most recent completed one whose
intent,desiredOutcome, orinScopematches the task. - If no relevant artifact exists, proceed with normal planning.
When a result.json artifact is available:
- treat it as the primary source of truth for intent, desired outcome, in-scope, out-of-scope, constraints, acceptance criteria, assumptions, technical context, and execution bridge
- use
spec.mdor the transcript only ifresult.jsonis insufficient - do not silently drift away from the artifact without naming the conflict
- if the live repo facts conflict with the artifact, call out the mismatch in the plan
- if the artifact is missing core planning fields, stop and report that the interview bundle is incomplete rather than planning from a hollow result
Steps
- Load the relevant
rein-interviewresult.jsonfirst when available. - List every discrete subtask required to complete the work.
- Identify dependencies between subtasks. Order them so each step has its prerequisites satisfied.
- Write each step in
change -> verifyform. - For each step, state:
- what changes
- why this is the minimum sufficient change
- what must stay untouched
- what could go wrong
- how to verify the step succeeded before moving on
- Reject speculative abstraction, flexibility, or helper extraction unless the plan explicitly justifies it.
- Identify the first safe checkpoint — the earliest point where the repo is in a valid state and work can be paused or reviewed.
- Identify rollback boundaries — points where a partial revert is clean rather than destructive.
- Flag any step that requires a decision the user has not yet made.
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.
- 7d ago First seen · 73 lines · 31 tokens per session scan A 6b0224090b3e
rein-plan is a cursor rule published in the GitHub repository jstxn/rein (12 stars, last pushed 4mo ago), licensed MIT. It adds 31 tokens to every session and 750 once invoked, about $0.0002 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.
Other cursor rules, from other repositories
ponytail
Ponytail, lazy senior dev mode. Always pick the simplest solution that works.
angular-20
This rule provides comprehensive best practices and coding standards for Angular development, focusing on modern TypeScript, standalone components, signals, and performance optimizations.
dev-standard
Apache Superset development standards and guidelines for Cursor IDE.
cli-error-handling
CLI command error handling patterns.
prefer-direct-imports-over-module-mocks
Prefer extracting a testable core over vi.mock / vi.resetModules when unit tests need to reach production logic entangled with config, env, or singletons.
control-plane-descriptors
Control plane descriptor and instance implementation patterns.