💰 December 2025: Anysphere (Cursor's parent company) valued at $29.3 billion after Series D funding, reflecting the explosive adoption of AI-assisted development.

Cursor is not just VS Code with AI - it's a fork that integrates LLMs directly into the rendering pipeline. This enables:

• Cursor Tab: Multi-line predictions (not just single line like Copilot)
• Composer: Autonomous multi-file editing agent
• Shadow Workspace: Background indexing for semantic search
• Native Diffs: Inline green/red diff visualization

Strategic thinking before coding. AI analyzes, plans, asks clarifying questions - then executes.

"Plan Mode forces 'measure twice, cut once' philosophy"

Millisecond codebase search. No more context hallucinations - agent verifies every reference instantly.

Run parallel agents using git worktrees:

• Agent 1: Refactoring component
• Agent 2: Writing tests
• No file lock conflicts

• 4x faster than general LLMs for diff-edit loops
• Codebase-wide semantic search
• Implicit checkpoints for instant rollback

→ Full 2.0/2.1 Guide

Some features were removed in 2.0/2.1:

→ Full Deprecated Features Guide

Popular "vibe coding" pattern for rapid prototyping:

1. Lovable → Design UI visually, connect to GitHub
2. Clone → Pull repo to local
3. Cursor → Add backend logic, APIs, complex features
4. Push → Sync back to Lovable

Users report building full SaaS products in 4 days using this hybrid approach.

→ Full Lovable + Cursor Guide

🎯 "Stability and polish" release - Major architectural improvements under the hood.

Extensions now run in an isolated process. If an extension crashes, AI keeps working:

Before: Extension crash → Everything freezes
After:  Extension crash → AI continues working ✅

This is critical for enterprise users with large codebases.

Four preset layouts with ⌘+⌥+⇥ (Mac) / Ctrl+Alt+Tab (Win):

• Service Accounts - Headless CI/CD automation
• SOC 2 Certified - Enterprise compliance ready
• Enforcement Hooks - Block sensitive data in prompts
• Linux Sandboxing - Container-friendly deployments

→ Full 2.3 Guide | → Enterprise Features

⚠️ DATA LOSS WARNING: Still active in 2.3. Read this before using Cursor.

• Cursor silently reverts your code minutes after saving
• Multi-file operations can cause cascade corruption
• Strongly linked to "Auto" mode and multiple agents

# BEFORE every agent operation:
git add -A && git commit -m "pre-agent-$(date +%s)"

→ Full Zombie Revert Guide | → Windows Terminal Fixes

🏆 HLE Benchmark Leader: 37.5% - Best reasoning performance ever recorded.

Architecture Planning  → Gemini 3 Pro (Free, best reasoning)
Daily Implementation   → Claude 3.5 Sonnet (Best bang-for-buck)
Legacy Refactoring     → Claude Opus 4.5 (Lowest risk)
Bulk Test Writing      → DeepSeek V3 (53x cheaper)

Settings → Codebase Indexing → Model → Gemini 3 Pro

→ Full Gemini 3 Pro Guide

⚠️ WARNING: Cursor 2.2 has critical bugs. See Cursor 2.2 Bugs before using.

Agent instruments your code with logging, you trigger the bug, agent analyzes runtime data for empirical debugging.

1. Describe bug → 2. Agent adds logging → 3. YOU trigger bug → 4. Agent analyzes → 5. Fix proposed

Bidirectional DOM ↔ Source Code editing. Select elements in browser, modify via GUI, changes write to source files.

Multiple agents solve your prompt in parallel. "Judge" agent picks the best solution. Increases token cost but improves quality.

→ Full 2.2 Features Guide | → 2.2 Bugs & Workarounds

Cmd + K  → "Fix this type error"
Cmd + L  → "Explain how auth works"  
Cmd + I  → "Refactor to use Axios instead of Fetch"

Pro Tip: Use Cmd + K for local scope, Cmd + I for global scope. Don't use Cmd + K for multi-file tasks.

→ Full Shortcuts Guide | → Development Workflows

Composer is Cursor's killer feature - an autonomous agent that can plan and execute multi-file edits.

Composer creates snapshots at each step. If the AI breaks something:

1. Click previous Checkpoint
2. Workspace reverts instantly
3. Try different approach

❌ Bad: "Add a login page"

✅ Good:

Implement a login route:
- @user_model.ts @auth_service.ts @routes.json
- Use Zod for validation
- Match error format in @errors.ts
- Create unit test in tests/auth/

→ Full Composer Guide

The AI is only as good as the context you provide.

@Codebase is probabilistic - if you call it "Login" 
but code says "SessionCreation", RAG may fail.

Use explicit @Files for critical tasks.

Create a current_task_spec Notepad with:

• PRD / Requirements
• Design constraints
• Architecture decisions

Reference with @current_task_spec in every new chat.

→ Full Context Guide | → Security Best Practices

System prompts that customize AI behavior per project.

Create .cursorrules in project root:

You are an expert TypeScript engineer.
Use functional components with Hooks.
Use Tailwind CSS for styling.
Never use CSS modules or styled-components.
Every function needs a unit test.

New system uses .cursor/rules/*.mdc with glob patterns:

---
description: "React Component Rules"
globs: ["src/**/*.tsx"]
alwaysApply: false
---

Use shadcn/ui for primitives.
Components in src/ui must be presentational only.
Business logic goes in src/services.

You are an expert engineer.
You DO NOT use placeholders.
You output the FULL content of the file every time.
You do not be lazy.

→ Full .cursorrules Guide | → .mdc Examples

🆕 GPT-5.2 (Dec 2025): 98.7% tool reliability, 128K output window, adaptive reasoning. → Full GPT-5.2 Guide

1. PLAN (Claude 4.5 / GPT-5.1 High):
   "Analyze request. Don't code. Create plan.md"
   
2. CRITIQUE (Gemini 3 Pro - optional):
   "Review plan.md for efficiency gaps"
   
3. EXECUTE (Composer / GPT-5.1):
   "Implement Step 1 of plan.md. Run tests."

Don't over-prompt! Give high-level goals:

❌ "Write function that does X, Y, Z step by step"
✅ "Goal: Implement resilient payment processor. 
    Reason about Stripe failure modes. Then output code."

Pro Plan ($20/mo):
├── Credit pool system (fast vs slow)
├── "Auto" mode switches models by task complexity
└── Set per-user spending limits (Enterprise)

Strategy:
├── Daily work → Pro Plan (Auto mode)
├── Heavy refactoring → BYOK Claude 4.5
├── Budget tasks → Kimi k2 via OpenRouter
└── Hard bugs → GPT-5.1 High Max

Warning: Don't switch models mid-conversation. It breaks the "train of thought."

→ Full Model Guide

Model Context Protocol lets Cursor connect to databases, GitHub, and browsers.

Create mcp.json in project root:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres", "${env:DATABASE_URL}"]
    }
  }
}

The most transformative MCP application:

1. Agent runs E2E test
2. Test fails (selector changed)
3. Agent analyzes DOM
4. Agent fixes test automatically
5. Agent verifies fix

→ Full MCP Guide

⚠️ As AI agents gain autonomy, security risks increase exponentially.

The ability of an Agent to execute shell commands and connect to the internet (via MCP) introduces new risks:

✅ Review all terminal commands before approval
✅ Use read-only MCP configurations
✅ Audit .mdc files in cloned repositories
✅ Never approve `env` or `printenv` commands
✅ Set strict YOLO mode restrictions
❌ Don't trust arbitrary @Docs sources
❌ Don't enable unrestricted shell access

⚠️ "Vibe Coding" can create unmaintainable code

If you don't understand the AI-generated code:
- You can't debug it when AI fails
- It becomes "Legacy Code" immediately
- Security vulnerabilities go unnoticed

→ Full Security Guide

Don't reuse Composer windows. One task = one Composer. Prevents context pollution.

git add -A && git commit -m "checkpoint"

→ Full Troubleshooting Guide

Tips from r/cursor power users:

If debugging exceeds ~20 messages, context is polluted. Start NEW chat with summary.

In Agent mode, Cursor sometimes deletes and recreates files instead of editing. Always commit before Agent sessions.

Paste UI bug screenshots directly into chat. Vision models diagnose CSS issues better than text descriptions.

Set hard limits in OpenAI/Anthropic dashboard. Runaway Agent loops can drain your credit card.

Don't switch from GPT-4o to Claude mid-task. Stick to one model per conversation.

→ Full Reddit Tips

1. Discovery: "Map usage of User component" (no code yet)
2. Plan: "Propose refactor plan, list affected files"
3. Critique: Review plan, challenge assumptions
4. Execute: Open Composer, paste approved plan
5. Audit: Review git diff line-by-line

1. "Write Vitest test for compound interest calculator"
2. Review test logic
3. "Now write function to pass this test"

1. Command fails in terminal
2. Click "Debug with AI" button
3. AI gets full error context automatically
4. Don't manually copy-paste errors

→ Full Workflows Guide

A critical differentiator between Cursor and Windsurf:

"Windsurf feels magical to new users, but terrifying to senior engineers who want to review every shell command."

Verdict: Cursor for control and precision. Antigravity for full automation experiments. Windsurf for auto-context (but watch the autonomy). Copilot for enterprise compliance.

→ Full Comparison | → Cursor vs Windsurf Deep Dive

The new development paradigm where domain experts focus on intent while AI implements.

⚠️ Warning: If you don't understand the AI-generated code, you can't debug it when AI fails. It becomes "Legacy Code" immediately.

Traditional: Developer writes code → Tests → Iterates
Vibe Coding: Developer describes intent → AI implements → Developer reviews

• Tradofire: Solo developer shipped complex crypto trading app
• Enterprise ERP: Full-scale systems built in weeks using TaskMaster workflow

1. Generate detailed PRD (Product Requirement Document)
2. Feed PRD to task management system
3. Agent parses PRD into individual tickets
4. Execute tickets one by one
5. Human review at each milestone

→ Full Vibe Coding Guide

The deployment of GPT-5.1 Codex (December 2025) introduced new capabilities and quirks.

The new "smart" model sometimes behaves "stupidly" due to over-reasoning and safety alignment:

• Over-analyzes simple requests
• Hallucinated constraints (e.g., insisting VPS is required)
• Conservative refusals on legitimate security utilities

Complex Architecture Planning → GPT-5.1 Codex Max (expensive)
Implementation Details       → Gemini 3 Pro or Claude Sonnet (cheaper)

Use Composer over raw chat — Cursor's agent harness improves model behavior significantly.

→ Full GPT-5.1 Codex Guide

Released December 11, 2025 — OpenAI's "Code Red" response to competitors.

• AIME 2025: 100% (math reasoning)
• SWE-Bench Pro: 55.6% (can solve majority of mid-level tickets)
• Tool Reliability: 98.7%

90% discount on cached inputs — ideal for IDE usage.

→ Full GPT-5.2 Guide

A powerful technique to combat AI hallucinations:

"Fix this only if you are 100% confident. Tell me your confidence score."

This prompt bypasses the "helpful assistant" persona and accesses the model's raw probability assessment, forcing it to:

1. Re-evaluate its own logic
2. Search for actual evidence
3. Admit uncertainty instead of hallucinating

→ Full Confidence Scoring Guide

UI shows diffs but files are never written to disk. Always verify file timestamps after accepting changes.

ls -la --time=modified <filename>
git diff

→ Full Known Bugs Guide

New competitor capturing "Early Adopter" mindshare with parallel agents and free preview.

The Hybrid Workflow: Users exhaust Cursor credits, then switch to free Antigravity.

→ Full Google Antigravity Guide

Sophisticated patterns from production teams:

If existing code is altered, warn by shouting:
❗️SHOUT WITH LARGE LETTERS❗️
"WARNING: Modified existing function in file.ts"

Presentation components must include "Dumb" in filename:
- UserProfileCardDumb.vue
- ProductListDumb.tsx

NEVER use page.waitForTimeout(5000)
ALWAYS use built-in auto-wait mechanisms
Target elements using data-testid attributes

→ Full Advanced .cursorrules Guide

Based on community intelligence:

1. Enforce Confidence Scoring: Mandate for all debugging tasks
2. Adopt Interface Freeze: Don't let AI define architecture
3. Implement Rigid .cursorrules: Copy "Dumb Component" and "Auto-Wait" patterns
4. Monitor Plan Bug: Verify file timestamps after every Accept
5. Session Reset Cadence: Clear context every 2-4 hours
6. Commit Before Agent: Always git commit -m "checkpoint"

1. Learn Cmd + K for inline edits
2. Learn Cmd + L for chat
3. Use @Files to add context

1. Master Cmd + I Composer
2. Create .cursorrules
3. Use @Codebase for exploration

1. Agent Mode with checkpoints
2. Custom .mdc rules per file type
3. Research-First protocol
4. BYOK API for heavy tasks

Ready-to-use configuration files for optimal Cursor setup:

// .cursor/mcp.json
{
  "mcpServers": {
    "playwright": {
      "command": "npx",
      "args": ["-y", "@playwright/mcp@latest"]
    }
  }
}

// .cursor/settings.json
{
  "agents": {
    "auto_apply_changes": false,
    "legacy_terminal_tool": true,
    "max_turns_per_session": 40
  },
  "models": {
    "codebase_indexing": "gemini-3-pro"
  }
}

→ Full MCP Config | → Full Settings | → React Rules | → Test Rules

Tests that automatically fix themselves when selectors change:

1. Agent runs E2E test
2. Test fails (selector changed)
3. Agent analyzes DOM
4. Agent updates selector
5. Test passes ✅

# 1. Create .cursor/mcp.json (see above)
# 2. Create .cursor/rules/testing.mdc
# 3. Enable auto-tools in settings

→ Full Playwright MCP Guide

• Official Docs
• r/cursor
• Cursor Forum
• awesome-cursorrules

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