A set of guidance for managing context, planning complex work, and troubleshooting failed builds. It also describes controls for extended thinking and plan mode.

It supports deciding which tasks need planning, keeping large refactors within the available context, and diagnosing build errors incrementally.

It helps avoid running out of working context during large tasks and gives a step-by-step response to build failures.

performance — Cursor rule for Cursor by fmflurry/settings-opencode

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.

Clone the repo

git clone --depth 1 https://github.com/fmflurry/settings-opencode

Made for: Cursor.

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/rules/fmflurry/settings-opencode/performance/github.svg)](https://agentmods.dev/rules/fmflurry/settings-opencode/performance)

Your own site

<a href="https://agentmods.dev/rules/fmflurry/settings-opencode/performance"><img src="https://agentmods.dev/badge/rules/fmflurry/settings-opencode/performance/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/rules/fmflurry/settings-opencode/performance"><img src="https://agentmods.dev/badge/rules/fmflurry/settings-opencode/performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 271 This file is loaded in full into every session.

When invoked 271 The same file — it is already loaded in full.

Security scan B 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	$0.00271	$0.00271
Opus 5.5	$0.00108	$0.00108
Sonnet 5.5	$0.00054	$0.00054
Haiku 4.5	$0.00027	$0.00027

Measured 8d ago against content hash 5ec5f150a849, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

performance scanned grade B 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 8d 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

- **Config**: Set `alwaysThinkingEnabled` in `~/.claude/settings.json`

plugins/fmflurry-harness/rules/performance.mdc · 43 lines

What it actually says

Performance Optimization

Context Window Management

Avoid last 20% of context window for:

Large-scale refactoring
Feature implementation spanning multiple files
Debugging complex interactions

Lower context sensitivity tasks:

Single-file edits
Independent utility creation
Documentation updates
Simple bug fixes

Extended Thinking + Plan Mode

Extended thinking is enabled by default, reserving up to 31,999 tokens for internal reasoning.

Control extended thinking via:

Toggle: Option+T (macOS) / Alt+T (Windows/Linux)
Config: Set alwaysThinkingEnabled in ~/.claude/settings.json
Budget cap: export MAX_THINKING_TOKENS=10000
Verbose mode: Ctrl+O to see thinking output

For complex tasks requiring deep reasoning:

Ensure extended thinking is enabled (on by default)
Enable Plan Mode for structured approach
Use multiple critique rounds for thorough analysis
Use split role sub-agents for diverse perspectives

Build Troubleshooting

If build fails:

Use build-error-resolver agent
Analyze error messages
Fix incrementally
Verify after each fix

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.

8d ago First seen · 43 lines · 271 tokens per session scan B 5ec5f150a849

Subscribe to this mod's changes

performance is a cursor rule published in the GitHub repository fmflurry/settings-opencode (171 stars, last pushed yesterday), licensed MIT. It adds 271 tokens to every session, about $0.0011 per session on Opus 5.5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-08.

Debugging Planning

error-handling-and-validation

A code-quality guide for handling errors, invalid inputs, edge cases, preconditions, logging, and user-friendly error messages.

holtwood/awesome-cursorrules-zh · 185 tokens

css-render-blocking-diagnosis

Cursor rule "css-render-blocking-diagnosis" from adobecom/da-express-milo, covering css render-blocking diagnosis & resolution, critical learning from 98 pagespeed achievement, primary diagnostic protocol, step 1: css blocking symptom recognition and step 2: css loading sequence audit.

adobecom/da-express-milo · 1,102 tokens

performance