A set of Cursor rules for a TypeScript project. Cursor is an AI coding editor, and the rules define coding, documentation, test-driven development (TDD), commit, and quality-check requirements.

Use it when modifying the cdt-smart-snapshot project. It requires writing tests before implementation, documents public functions, enforces TypeScript restrictions, uses Conventional Commits, and runs formatting, type checks, and tests.

It gives the editor clear project standards and prevents common issues such as unsafe types, undocumented public functions, and untested production code.

How sinnhirl/cdt-smart-snapshot configures Cursor

Reuse

Borrowing it

Nothing to install: this file belongs to sinnhirl/cdt-smart-snapshot. 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/sinnhirl/cdt-smart-snapshot/main/.cursorrules

Clone the repo

git clone --depth 1 https://github.com/sinnhirl/cdt-smart-snapshot

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/sinnhirl/cdt-smart-snapshot/cursorrules/github.svg)](https://agentmods.dev/rules/sinnhirl/cdt-smart-snapshot/cursorrules)

Your own site

<a href="https://agentmods.dev/rules/sinnhirl/cdt-smart-snapshot/cursorrules"><img src="https://agentmods.dev/badge/rules/sinnhirl/cdt-smart-snapshot/cursorrules/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/sinnhirl/cdt-smart-snapshot/cursorrules"><img src="https://agentmods.dev/badge/rules/sinnhirl/cdt-smart-snapshot/cursorrules.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 401 This file is loaded in full into every session.

When invoked 401 The same file — it is already loaded in full.

Security scan A 0 findings. 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	$0.00401	$0.00401
Opus 5.5	$0.00160	$0.00160
Sonnet 5.5	$0.00080	$0.00080
Haiku 4.5	$0.00040	$0.00040

Measured 2mo ago against content hash 98d77e14da1b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cursorrules 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.

.cursorrules · 34 lines

What it actually says

cdt-smart-snapshot project rules (AI must comply)

TypeScript hard rules (violation = rewrite)

No any type; no as type assertions; no ! non-null assertions
No // @ts-ignore, // @ts-nocheck, // @ts-expect-error comments
Prefer for..of over forEach
Use import type for type-only imports; prefer interface over type for shapes
Use simple Array<T> form (array-simple rule)

Comments (mandatory — user requirement)

Every public function/method needs JSDoc: @param, @returns, @throws
Core algorithms (visibility/diff/dedupe) need a "why" comment at the top of each function
Inline comments explain intent on complex logic; never translate code line by line

TDD (iron law)

Write the test first, watch it fail (RED), then minimal implementation (GREEN), then refactor (REFACTOR)
No production code without a failing test
Test naming: shouldXxxWhenYyy format

Commit conventions

Conventional Commits: feat:/fix:/docs:/chore:/refactor:/test:
Title line ≤ 72 chars

Quality gates

npm run check-format must be zero-error
npm run typecheck must be zero-error
npm run test must be all green

Project background (read before writing code)

Positioning: token-efficient perception layer for chrome-devtools-mcp, 3 tools: smart_snapshot (semantic snapshot) / snapshot_diff (incremental) / screenshot_to_disk (file path)
Stack: Node 22 + TypeScript ESM + @modelcontextprotocol/sdk v1 + puppeteer-core + vitest
Full spec is in SPEC.md — implement per that spec

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 · 34 lines · 401 tokens per session scan A 98d77e14da1b

Subscribe to this mod's changes

cursorrules is a cursor rule published in the GitHub repository sinnhirl/cdt-smart-snapshot (0 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 401 tokens to every session, about $0.0016 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 2026-08-31.

cursorrules next to 6 cursor rules from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
cursorrulessinnhirl/cdt-smart-snapshot	Cursor rule	0	3mo ago	Apache-2.0	A	401	Cursor
ponytailDietrichGebert/ponytail	Cursor rule	185k	8d ago	MIT	A	604	Cursor
angular-20angular/angular	Cursor rule	101k	yesterday	MIT	A	0	Cursor
dev-standardapache/superset	Cursor rule	75k	yesterday	Apache-2.0	A	1,147	Cursor
prefer-assertions-over-defensive-checksprisma/orm	Cursor rule	48k	yesterday	Apache-2.0	A	0	Cursor
prefer-direct-imports-over-module-mocksprisma/orm	Cursor rule	48k	yesterday	Apache-2.0	A	0	Cursor
shared-plane-packagesprisma/orm	Cursor rule	48k	yesterday	Apache-2.0	A	0	Cursor

cdt-smart-snapshot: Cursor rule for Cursor