fix(init): --agent cursor installs Cursor only and creates ~/.cursor

[rNoz]

Summary

Two defects made rtk init -g --agent cursor fail / pollute the home dir:

1. It fell through to the shared init path with install_claude derived only from !opencode, so it created RTK.md, CLAUDE.md, and patched settings.json under ~/.claude in addition to patching .cursor/hooks.json. On machines without ~/.claude it failed outright: Failed to create temp file in ~/.claude: No such file or directory.
2. Even after removing the .claude writes, the Cursor path still failed on a fresh machine because install_cursor_hooks never created ~/.cursor before atomic_write placed its temp file there.

Fixes:

• Gate install_claude on the absence of a sibling agent target (Cursor, Windsurf, Cline), so only the default or an explicit Claude target installs Claude Code files.
• Create ~/.cursor (non-dry-run) before patching hooks.json.
• Should complete/close rtk init -g --agent cursor fails #2097 (same root cause as the previously-closed bug: "rtk init -g --agent cursor" errors due to expecting $HOME/.claude #1465)

Root cause

• src/main.rs, Commands::Init handler: install_claude = !opencode. Cursor is the only sibling agent that reaches the shared init path (Windsurf/Cline short-circuit earlier in hooks::init::run), so it incorrectly triggered the Claude install branch.
• src/hooks/init.rs, install_cursor_hooks: wrote hooks.json via atomic_write without ensuring the parent directory exists.

Fix

// src/main.rs
let install_cursor = agent == Some(AgentTarget::Cursor);
let install_windsurf = agent == Some(AgentTarget::Windsurf);
let install_cline = agent == Some(AgentTarget::Cline);
let install_claude =
    !opencode && !install_cursor && !install_windsurf && !install_cline;

// src/hooks/init.rs (install_cursor_hooks)
if !dry_run {
    fs::create_dir_all(&cursor_dir)?;
}

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test --all: pass.
• New tests/init_agent_cursor_test.rs:
  • agent_cursor_dry_run_never_touches_claude: asserts dry-run output contains no /.claude/ path and does patch /.cursor/.
  • agent_cursor_real_write_creates_no_claude_dir: non-dry-run install in a temp HOME: exits 0, never creates ~/.claude, and writes .cursor/hooks.json.
  • default_dry_run_still_installs_claude: regression: default init still installs Claude Code files.
• cargo test --bin rtk hooks::init: 169 existing init tests pass (no regression).

E2E Validation

Tested locally and providing proofs (Screenshot). All working as expected:

[tapheret2]

Review: fix(init): --agent cursor installs Cursor only and creates ~/.cursor

Files: src/hooks/init.rs, src/main.rs, tests/init_agent_cursor_test.rs
Size: +93 / -1

Notes

• Tests/fixtures present — good signal for correctness.

Thanks @rNoz — independent review on the patch.

[rNoz]

Tested E2E locally with my local rnoz/integration branch. All working as expected. See the capture. Ready for review/merge.