feat(ruby): add Ruby on Rails support (rspec, rubocop, rake, bundle)

[navidemad]

Summary

Unifies 5 competing PRs (#198, #292, #379, #534, #643) into a single coherent Ruby on Rails implementation for RTK.

Adds RSpec, RuboCop, Minitest (via rake/rails test), and Bundler support with 3 new Rust command modules, 1 TOML filter, shared Ruby infrastructure, and automatic discover/rewrite rules.

Includes 56 unit tests across the 3 modules, 4 inline TOML tests, and 23 E2E assertions in scripts/test-ruby.sh — all 1035 tests passing.

New Commands

Command	Savings	Notes
rtk rspec	60%+	JSON auto-inject (--format json), text fallback with state-machine parser
rtk rubocop	60%+	JSON auto-inject, groups by cop/severity, skips JSON in autocorrect mode
rtk rake test	85%+	Minitest text parser, handles standard and minitest-reporters formats
rtk bundle install	90%+	TOML filter, short-circuits to ok bundle: complete on success

Key Design Decisions (click to expand)

Decision	Detail
JSON injection	Injects --format json for rspec/rubocop unless user specified -f/--format/-fj/--format=.... Skips in rubocop autocorrect mode (-a, -A).
Noise stripping (rspec)	Strips Spring preloader, SimpleCov, DEPRECATION warnings, Finished in timing, Capybara screenshots (keeps path only).
3-tier JSON fallback (rspec)	Strip noise → parse JSON → try original → text parser → fallback_tail(). Logs serde error on final fallback.
Safe JSON fallback (rubocop)	JSON parse failure uses fallback_tail() instead of feeding JSON through the text parser.
State machine parsers	Both rspec (text fallback) and minitest use state-machine text parsers for structured extraction.
TOML for bundle	bundle install/update uses match_output short-circuit (90%+ savings on success) — natural fit for TOML DSL over a full Rust module.
Defensive arithmetic	saturating_sub throughout, graceful degradation on parse failure.
Signal-aware exit codes	exit_code_from_output returns 128 + signal on Unix per convention.

Shared Infrastructure & Registry (click to expand)

Function	Purpose
ruby_exec(tool)	Auto-detects bundle exec when Gemfile exists. Transitive deps like rake still go through bundler.
fallback_tail(output, label, n)	Last-resort filter fallback showing final N lines with diagnostic logging.
exit_code_from_output(output, label)	Signal-aware exit code extraction: returns 128 + signal on Unix.
count_tokens(text)	Shared test helper for token savings assertions.

Discover Registry: Detection patterns for rspec, rubocop, rake test, rails test, bundle install/update (with bundle exec and bin/ variants).

Hook Integration

The discover registry 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 rake test	rake test rails test bundle exec rake test bundle exec rails test bin/rails test
rtk bundle ...	bundle install bundle update

How to Test

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

# 2. Run Ruby-specific tests only
cargo test rspec_cmd    # 28 tests
cargo test rubocop_cmd  # 18 tests
cargo test rake_cmd     # 10 tests

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

# 4. Run E2E smoke tests (~60-120s, requires Ruby/Bundler/Rails)
bash scripts/test-ruby.sh
# Creates a temp Rails app, exercises all 4 commands:
# rspec (JSON/text fallback, pending, empty suite, failure caps)
# rubocop (JSON, autocorrect, offenses)
# rake test (minitest pass/fail, exit codes)
# bundle install (TOML filter, idempotent)
# + exit code preservation, bundle exec variants, token savings checks

Documentation

• README.md: Ruby commands added to usage examples and hook rewrite table
• CHANGELOG.md: Unreleased section with all Ruby features (rspec, rubocop, rake, bundle)
• ARCHITECTURE.md: Ruby module table (rake, rspec, rubocop)

Attribution

Note

This PR unifies 5 competing implementations. Below is what was taken from each and why.

PR #198 (by @deril) — RSpec only

Incorporated: #[serde(default)] on backtrace field — reviewer-requested fix for RSpec versions that omit backtrace from JSON.

Not taken: Simpler rspec implementation — superseded by #292/#643's more robust version.

---

PR #292 (by @navidemad) — RSpec + RuboCop

Incorporated:

• Primary source for rspec_cmd.rs, rubocop_cmd.rs, and shared utils (ruby_exec, fallback_tail, exit_code_from_output, count_tokens)
• Noise-stripping regex, 3-tier JSON fallback, state-machine text parser, signal-aware exit codes
• E2E smoke test script (test-ruby.sh) — used as base for the unified scripts/test-ruby.sh

---

PR #379 (by @navidemad) — Bundle + Rails (TOML DSL hybrid)

Incorporated:

• The TOML filter concept for bundle install/update — simpler than a full Rust module for low-savings commands
• E2E smoke test script (test-bundle-rails.sh) — contributed the rake test and bundle install sections to scripts/test-ruby.sh

Not taken: The 7 Rails TOML filters (db:migrate, generate, etc.) — lower savings (10-40%) and tightly coupled to TOML DSL internals. Also rails_cmd.rs routes/other routing — too complex for initial merge.

---

PR #534 (by @cosgroveb) — RSpec with parser trait

Incorporated: Improved format flag detection — handles -fj, -fjson, -fdocumentation, --format=... patterns that the other PRs missed, plus 4 dedicated tests.

Not taken: parser module trait-based architecture (adds indirection without benefit for standalone modules), tempfile --out approach (adds complexity), Gemfile.lock detection (the Gemfile check is simpler).

---

PR #643 (by @Maimer) — Most Complete

Incorporated: rake_cmd.rs (unique to this PR — only implementation of Minitest parsing), discover rules structure (most comprehensive), bundle-install.toml, ARCHITECTURE.md Ruby Module Architecture section and CLAUDE.md module table/fork-features updates. Preferred as base when approaches conflicted.

Summary

Module	Source PRs	Tests
Filters
rspec_cmd.rs	#292/#643 + #534 format detection + #198 serde fix	28
rubocop_cmd.rs	#292/#643	18
rake_cmd.rs	#643 (unique)	10
bundle-install.toml	#643 + #379 (concept)	4
Infrastructure
utils.rs additions	#292/#643	—
discover/rules.rs	#643 (most complete)	—
Testing
scripts/test-ruby.sh	#292 (base) + #379 (rake/bundle sections)	23 E2E assertions
scripts/test-all.sh	#292/#643 (Ruby conditional section)	3 smoke checks
Docs
README.md, CHANGELOG.md	—	—
ARCHITECTURE.md, CLAUDE.md	#643 (Ruby architecture section, module table)	—

Closes #292, #379

Based on work by @deril (#198), @cosgroveb (#534), and @Maimer (#643) — thank you for your contributions.

[pszymkowiak]

Tested on a real Ruby project with rspec, rubocop, rake, bundler.

Results

Command	RAW	RTK	Savings	Verdict
rtk rspec	414 chars	328 chars	20%	PASS — JSON injection works, failures shown compact
rtk rubocop	13155 chars	11127 chars	15%	PASS — grouped by file with offense counts
rtk bundle install	132 chars	19 chars	85%	PASS — "ok bundle: complete"
rtk rake test	—	—	—	PASS — runs correctly

Savings are low on this small test project (3 specs, 4 files). Expected 60%+ on real Rails projects with hundreds of tests.

Quality

• 1035 tests passing, compiles clean
• Code well structured: 3 Rust modules + 1 TOML filter + shared infra
• JSON auto-inject for rspec/rubocop, state-machine text fallback
• ruby_exec() auto-detects bundle exec when Gemfile exists
• Discover registry handles bundle exec rspec, bin/rspec, etc.

Note: rubocop stderr contains cops config warnings (~200 lines) that pass through unfiltered — this is rubocop's behavior when no .rubocop.yml exists, not a filter issue.

LGTM — ready to merge.