feat: add Ruby and Rails CLI support (rspec, rubocop, bundle, rails)

[navidemad]

📝 Summary

Adds comprehensive Ruby and Rails ecosystem support to RTK with 4 new command modules covering the full Rails development workflow, plus shared infrastructure and discover registry integration.

Includes 97 unit tests across the 4 new modules and an E2E smoke test script (scripts/test-rails.sh) that creates a real Rails app and exercises all commands.

🚀 New Commands

Command	Supported Subcommands / Formats	Token Savings	Notes
rtk rspec	JSON, Text fallback		Injects --format json automatically. Falls back to text parsing when user specifies a custom format.
rtk rubocop	Standard, Autocorrect		Injects --format json, groups offenses by cop name and severity. Skips JSON in autocorrect mode (-a, -A).
rtk bundle	list, outdated, install, update		Text parsing with subcommand dispatch. ANSI stripping at entry point.
rtk rails	test, routes, db:migrate, db:migrate:status, db:rollback, generate		Sub-enum with per-subcommand parsers. Minitest parser for test, route grouping for routes, migration summaries for db:*.

🛠 Key Design Decisions (Click to expand)

1. JSON injection for rspec/rubocop — Injects --format json unless user specified -f/--format. Detects autocorrect mode (-a, -A) in rubocop to skip JSON.
2. 3-tier JSON fallback in rspec — Strip noise → parse JSON → try original → text parser → fallback_tail(). Logs serde error on final fallback for debugging.
3. Safe JSON fallback in rubocop — JSON parse failure uses fallback_tail() instead of feeding JSON through the text parser.
4. Sub-enum for rails, flat dispatch for bundle — Rails has 6 subcommands with different output formats; Bundle has 4 with shared structure. Mirrors existing patterns (Go uses sub-enum, Ruff uses flat args).
5. Defensive arithmetic — saturating_sub throughout, extract_count returns Option<usize> to distinguish 0 from parse error.
6. Signal-aware exit codes — exit_code_from_output returns 128 + signal on Unix per convention, ANSI stripping at filter entry points.

🏗 Shared Infrastructure & Registry (Click to expand)

Shared Infrastructure (utils.rs)

• ruby_exec() — Auto-detects bundle exec when Gemfile declares the tool gem. gemfile_mentions_gem() avoids false positives (e.g., guardrails ≠ rails).
• fallback_tail() — Last-resort filter fallback showing final N lines with diagnostic logging.
• count_tokens() — Shared test helper for token savings assertions (deduplicated from 4 modules).
• exit_code_from_output() — Signal-aware exit code extraction: returns 128 + signal on Unix per convention.

Discover Registry

• Patterns use non-capturing groups (?:bundle\s+exec\s+)? so the subcommand lands in capture group 1.
• db:migrate:status ordered before db:migrate to avoid prefix match.
• Subcommand-specific savings:
  • test: 50%
  • routes: 50%
  • db:migrate:status: 40%
  • db:migrate / db:rollback: 40%
  • generate/g: 20%

🪝 Hook Integration

The .claude/hooks/rtk-rewrite.sh file now correctly rewrites the following commands:

Rewritten to	From input
rtk rspec	rspec, bundle exec rspec, bin/rspec
rtk rubocop	rubocop, bundle exec rubocop
rtk bundle …	bundle list|outdated|install|update
rtk rails …	rails test|routes|db:migrate|…
rtk rails …	rake routes|db:migrate|db:rollback|…
rtk rails …	bin/rails …, bundle exec rails …

🧪 How to Test

Tip

Running the E2E smoke tests requires Ruby, Bundler, and the Rails gem to be installed locally.

# 1. Run unit tests (No Ruby required)
cargo test --all

# 2. Build and install locally
cargo install --path .

# 3. Run E2E smoke tests (~60-120s execution time)
bash scripts/test-rails.sh

[benoittgt]

Partially duplicate of #198

But great additions !