Vibe Coding Setup Helper with AI

I'm a beginner trying to set up Claude Code (Anthropic's CLI tool) and I'm stuck. When I run `claude` and try `/login`, it blocks me and says I need an API key instead of letting me sign in with my Claude.ai account. I've never intentionally set up an API key.

Don't ask me questions about my setup — inspect my machine yourself and figure it out. I'm a beginner and I won't know the answers reliably.

Run diagnostic commands on this device to determine:

1. My OS (macOS / Windows / Linux) and shell (bash / zsh / PowerShell)
2. Which terminal/IDE I'm running in — check env vars like TERM_PROGRAM, VSCODE_INJECTION, CURSOR_*, __CFBundleIdentifier
3. How Claude Code was installed — check `which claude`, look for it under npm global, Homebrew, or the official installer path (~/.local/bin/ or ~/.claude/local/)
4. Whether ANTHROPIC_API_KEY is set — check the current shell env AND grep my shell config files (~/.zshrc, ~/.bashrc, ~/.bash_profile, ~/.zprofile, ~/.profile, ~/.config/fish/config.fish)
5. Whether my IDE is injecting a key — check VS Code/Cursor settings.json for `claude.*` or `anthropic.*` entries, and any `.env` files in my home dir or current project
6. Whether ~/.claude/settings.json or ~/.claude/.credentials.json has an API key configured
7. Whether the install is stale or broken — check `claude --version` against the latest, and look for duplicate installs on PATH

Once you've gathered the evidence, give me a step-by-step fix tailored to what you actually found — not generic advice. Format each step like this:

▎ Step N: [What this does in plain English]
▎ <one command I can copy-paste>
▎ [What I should see after running it]

Rules:
- One step at a time. Wait for me to confirm before moving on.
- Every command must be copy-paste ready for my shell (don't give me bash syntax if I'm on PowerShell).
- If you need to edit a config file, give me the exact command to open it (e.g. `open -e ~/.zshrc` on Mac) — don't assume I know how.
- The goal is a working `/login` browser flow so I can sign in with my Claude.ai account. No API key.
- If you find an ANTHROPIC_API_KEY somewhere, tell me exactly which file, which line, and the exact command to remove it.

Start by running the diagnostics. Don't ask me anything until you've inspected the machine.

I want to install iTerm2 (version 3.5+) on my Mac and enable "Allow clipboard access" so I can paste screenshots into Claude Code. Don't ask me questions — inspect my machine yourself and figure it out. I'm a beginner, give me ONE step at a time, copy-paste ready commands, wait for me to confirm "done" before sending the next one.

Run diagnostic commands first to determine:
1. Confirm I'm on macOS (run: `sw_vers`)
2. Check if Homebrew is installed (run: `brew --version`) — if not, the first step should install it
3. Check if iTerm2 is already installed (run: `ls /Applications | grep -i iterm`)
4. If iTerm2 is installed, check the version (run: `defaults read /Applications/iTerm.app/Contents/Info.plist CFBundleShortVersionString`) and tell me whether I need to update

Then, based on what you found, give me a step-by-step plan:
- Install Homebrew if missing
- Install iTerm2 via `brew install --cask iterm2` (or upgrade if already installed but old)
- Enable clipboard access by running: `defaults write com.googlecode.iterm2 AllowClipboardAccess -bool true`
- Tell me to fully quit and reopen iTerm2 so the setting takes effect
- Walk me through the GUI confirmation: Settings → General → Selection → confirm "Applications in terminal may access clipboard" is checked

Format each step like this:

▎ Step N: [What this does in plain English]
▎ <one command I can copy-paste>
▎ [What I should see after running it]

Rules:
- ONE step at a time. Wait for me to say "done" before moving on.
- Every command must be copy-paste ready — no placeholders.
- If you need me to click something in iTerm2's GUI, tell me exactly which menu, in plain English ("click iTerm2 in the menu bar at top of screen, then Settings, then General tab, then Selection sub-tab").
- After everything is set up, give me a final "test it" step: take a screenshot with Cmd+Shift+4, paste with Cmd+V into a Claude Code prompt running inside iTerm2, and confirm the image appears.

If you find iTerm2 is already installed AND already version 3.5+ AND clipboard access is already enabled, just tell me and skip to the test step.

Don't tell me "this isn't possible" — figure it out. Start with the diagnostic commands now.