Borrowing it
Nothing to install: this file belongs to kaininx/PlainTab. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/kaininx/PlainTab/main/AGENTS.mdgit clone --depth 1 https://github.com/kaininx/PlainTabWrote 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/instructions/kaininx/plaintab/agents-md)<a href="https://agentmods.dev/instructions/kaininx/plaintab/agents-md"><img src="https://agentmods.dev/badge/instructions/kaininx/plaintab/agents-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.
<a href="https://agentmods.dev/instructions/kaininx/plaintab/agents-md"><img src="https://agentmods.dev/badge/instructions/kaininx/plaintab/agents-md.svg" alt="Reviewed on agentmods" width="80" 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 | $0.01043 | $0.01043 |
| Opus 5.5 | $0.00417 | $0.00417 |
| Sonnet 5.5 | $0.00209 | $0.00209 |
| Haiku 4.5 | $0.00104 | $0.00104 |
Grade A, and why
PlainTab AGENTS.md 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 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.
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 — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md
Shared instructions for AI agents working on PlainTab.
PlainTab is a Chrome/Edge Manifest V3 new-tab extension. It is also able to run as a standalone web page by opening index.html directly.
Rule Priority
Use this order when instructions conflict:
.claude/rules/00-core.md- The matching file under
.claude/rules/ - This
AGENTS.md - Tool-specific adapters such as
CLAUDE.md - Reference docs and task notes
Before changing core behavior, read 00-core.md and the relevant module rule. Use .claude/rules/README.md as the rule map.
Project Constraints
Do not introduce:
- Build tools
npmorpackage.json- Frontend frameworks
- Lint or test frameworks
- Large runtime dependencies
Use vanilla JavaScript, native CSS, and static browser extension assets.
Required Rule Files
- Rule map:
.claude/rules/README.md - Core behavior:
.claude/rules/00-core.md - Storage, IndexedDB, localStorage, migrations:
.claude/rules/10-storage.md - Wallpaper rendering, first paint, image lifecycle:
.claude/rules/20-wallpaper.md - Language detection and fallback:
.claude/rules/30-language.md - Startup flow and global interactions:
.claude/rules/40-runtime.md - Search behavior:
.claude/rules/50-search.md - Settings panel UI and state:
.claude/rules/60-settings.md - Command palette:
.claude/rules/70-command-palette.md
Startup Invariants
index.html loading order is part of the zero-white-flash design:
#wallpaperBackexists firstjs/preload.jsruns synchronously#wallpaperFrontexists- Other DOM follows
js/languages.js- Main runtime scripts
Do not move preload.js, make it async, or add network work to the first-paint path.
Wallpaper And Storage Safety
The wallpaper system uses a stable back layer and a transition front layer. At least one layer must always have visible content.
Storage safety rules:
- Write large data before writing references
- Remove references before deleting large data
- Access IndexedDB through the storage module, not from unrelated UI code
- Revoke Blob URLs when they are no longer needed
- Preserve localStorage key compatibility unless a migration exists
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 · 135 lines · 1,043 tokens per session scan A a6559de01d13
PlainTab AGENTS.md is an instructions file published in the GitHub repository kaininx/PlainTab (96 stars, last pushed 5mo ago), licensed MIT. It adds 1,043 tokens to every session, about $0.0042 per session on Opus 5.5. 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 instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
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Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
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vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deno copilot-instructions.md
Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.