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

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Summary

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

New Commands

Command	Strategy	Token Savings
rtk rspec	JSON (--format json injection) with text fallback
rtk rubocop	JSON (--format json injection) with text fallback
rtk bundle list/outdated/install/update	Text parsing, subcommand dispatch
rtk rails test/routes/db:migrate/db:migrate:status/db:rollback/generate	Sub-enum, text parsing per subcommand

Shared Infrastructure

• ruby_exec() in utils.rs — Auto-detects bundle exec when Gemfile declares the tool gem. Prevents forcing globally-installed tools through bundler. gemfile_mentions_gem() avoids false positives (e.g., guardrails ≠ rails)
• fallback_tail() in utils.rs — Last-resort filter fallback showing final N lines with diagnostic logging
• count_tokens() in utils.rs — 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, logs signal number

Hook Integration

.claude/hooks/rtk-rewrite.sh rewrites:

• rspec, bundle exec rspec, bin/rspec → rtk rspec
• rubocop, bundle exec rubocop → rtk rubocop
• bundle list/outdated/install/update → rtk bundle ...
• rails test/routes/db:migrate/db:migrate:status/db:rollback/generate → rtk rails ...
• rake routes/db:migrate/db:migrate:status/db:rollback → rtk rails ...
• bin/rails, bundle exec rails variants

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 40%, db:rollback 40%, generate/g 20%

Key Design Decisions

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. ANSI stripping in bundle list — strip_ansi() at filter entry point to handle colored terminal output

Changes by File

File	Lines	Description
src/rspec_cmd.rs	+974	RSpec filter: JSON/text parsers, noise stripping, 27 tests
src/rails_cmd.rs	+1452	Rails sub-enum: test/routes/migrate/status/rollback/generate, 35 tests
src/rubocop_cmd.rs	+661	RuboCop filter: JSON/text parsers, severity ordering, 20 tests
src/bundle_cmd.rs	+637	Bundle filter: list/outdated/install/update with ANSI handling, 15 tests
scripts/test-rails.sh	+334	E2E smoke test (creates real Rails app, exercises all commands)
src/discover/registry.rs	+236	Pattern matching + subcommand savings for Ruby ecosystem
src/utils.rs	+142	ruby_exec(), fallback_tail(), count_tokens(), signal handling
src/main.rs	+114	Command routing for rspec, rubocop, bundle, rails
.claude/hooks/rtk-rewrite.sh	+48	Hook rewrites for Ruby/Rails commands
scripts/test-all.sh	+32	Smoke test additions
README.md	+37	Documentation
CLAUDE.md	+16	Module table, hook docs, architecture notes
ARCHITECTURE.md	+21	Module table entry

PR Review Fixes (2 rounds, 27 issues addressed)

Round 1 (issues 1-14)

#	Severity	Fix
1	Critical	saturating_sub in build_rspec_summary (prevents underflow panic)
2	Critical	RuboCop JSON fallback uses fallback_tail() instead of text parser
3	Bug	Removed dead output.status.success() check in signal handler
4	Bug	bundle_cmd::run_passthrough uses exit_code_from_output
5	Bug	extract_count returns Option<usize> (0 vs parse error)
6	Bug	Discover registry: non-capturing groups, added db:rollback/generate/g
7	Docs	Qualified savings claims (RSpec: 60%+/30%+; Bundle: 10-30%)
8-10	Test	ANSI handling tests for all 4 modules, text fallback truncation
11	Test	Empty migration table test
12	Test	RuboCop 10-file cap test
13-14	Docs	Inline comments (bundle ruby_exec skip, migrate direction docs)

Round 2 (issues 1-13, skipping 9)

#	Severity	Fix
1	Registry	Added db:migrate:status to discover PATTERNS and subcmd_savings + test
2	Bug	Removed spurious starts_with(") ") in rspec text parser
3	Diagnostics	RSpec JSON fallback now logs the serde error message
4	Diagnostics	Minitest error count sanity check (parallel to failure count check)
5	Bug	Signal termination returns 128 + signal on Unix (was hardcoded 1)
6	Bug	strip_ansi() in filter_bundle_list() + improved ANSI test assertions
7	Docs	exit_code_from_output doc comment reflects 128 + signal behavior
8	Cleanup	Deduplicated count_tokens to shared utils.rs (removed from 4 modules)
9	Skip	Run boilerplate refactor deferred (functions have enough variation)
10	Docs	compact_ruby_path doc comment accurately describes behavior
11	Docs	Bundle savings "5-30%" → "10-30%" in CLAUDE.md and ARCHITECTURE.md
12	Docs	Added rake variants to hook integration docs
13	Test	Added Header → FailedExamples transition test for rspec text parser

Testing

cargo fmt --all --check   → clean
cargo clippy --all-targets → 0 new warnings
cargo test --all           → 527 passed, 2 ignored

Test Plan

• cargo fmt --all --check && cargo clippy --all-targets && cargo test --all passes
• Build release binary and verify filtered output on a real Rails project
• Verify hook rewrites in a Claude Code session (rspec → rtk rspec)
• Run scripts/test-rails.sh on a machine with Ruby/Rails
• Verify rtk gain --history records Ruby/Rails usage
• Test format flag: rtk rspec -fdocumentation uses text fallback
• Test failure path: rtk rspec in empty dir shows "FAILED" message
• Verify rtk rails db:migrate:status, db:rollback, generate work correctly
• Verify rtk discover detects rails db:migrate:status as supported

🤖 Generated with Claude Code

[navidemad]

Moved to rtk-ai#292