feat(ruby): add Ruby on Rails command support

ARCHITECTURE.md

@@ -272,6 +272,10 @@ PYTHON            ruff_cmd.rs       ruff check/format      80%+       ✓
 GO                go_cmd.rs         go test/build/vet      75-90%     ✓
                   golangci_cmd.rs   golangci-lint          85%        ✓
 
+RUBY              rake_cmd.rs       rake/rails test        85-90%     ✓
+                  rspec_cmd.rs      rspec                  60%+       ✓
+                  rubocop_cmd.rs    rubocop                60%+       ✓
+
 NETWORK           wget_cmd.rs       wget                   85-95%     ✓
                   curl_cmd.rs       curl                   70%        ✓
 
@@ -303,6 +307,7 @@ SHARED            utils.rs          Helpers                N/A        ✓
 - **JS/TS Tooling**: 8 modules (modern frontend/fullstack development)
 - **Python Tooling**: 3 modules (ruff, pytest, pip)
 - **Go Tooling**: 2 modules (go test/build/vet, golangci-lint)
+- **Ruby Tooling**: 3 modules (rake/minitest, rspec, rubocop) + 1 TOML filter (bundle install)
 
 ---
 
@@ -605,6 +610,86 @@ pub fn run(command: &GoCommand, verbose: u8) -> Result<()> {
 - Different output format (JSON API vs text)
 - Distinct use case (comprehensive linting vs single-tool diagnostics)
 
+### Ruby Module Architecture
+
+#### Design Rationale
+
+**Added**: 2026-03-15
+**Motivation**: Ruby on Rails development support (minitest, RSpec, RuboCop, Bundler)
+
+Ruby modules follow the standalone command pattern (like Python) with a shared `ruby_exec()` utility for auto-detecting `bundle exec`.
+
+```
+┌────────────────────────────────────────────────────────────────────────┐
+│                      Ruby Commands (3 modules + 1 TOML)               │
+└────────────────────────────────────────────────────────────────────────┘
+
+Module            Strategy              Output Format      Savings
+─────────────────────────────────────────────────────────────────────────
+
+rake_cmd.rs       STATE MACHINE         Text parser       85-90%
+
+  Minitest output (rake test / rails test):
+    # Running:
+    ..F..E..
+    Finished in 0.123456s
+    1) Failure: TestSomething#test_that_fails [path:15]
+
+  → State machine: Header → Running → Failures → Summary
+  → All pass: "ok rake test: 8 runs, 0 failures"
+  → Failures: summary + numbered failure details
+  → Handles both standard Minitest and minitest-reporters formats
+
+rspec_cmd.rs      JSON/TEXT DUAL        • JSON → 60%+    60%+
+                                        • text fallback
+
+  rspec --format json: Structured test results
+  → Extract failures with file:line, assertion message
+  → Fallback to text parsing when JSON unavailable
+
+rubocop_cmd.rs    JSON PARSING          JSON API          60%+
+
+  rubocop --format json:
+    {"files": [{"path": "x.rb", "offenses": [...]}]}
+  → Group by cop name and severity
+  → Format: "Layout/LineLength: 12 offenses, Style/HashSyntax: 5"
+
+bundle-install.toml  TOML FILTER       Text rules        70%
+
+  bundle install/update:
+  → Strip "Using" lines (cached gems), metadata, blank lines
+  → Short-circuit: "ok bundle: complete" on success
+```
+
+#### Shared Infrastructure: `ruby_exec()`
+
+```rust
+// utils.rs — auto-detect bundle exec
+pub fn ruby_exec(tool: &str) -> Vec<String> {
+    if Path::new("Gemfile").exists() {
+        vec!["bundle".into(), "exec".into(), tool.into()]
+    } else {
+        vec![tool.into()]
+    }
+}
+```
+
+Used by: rake_cmd, rspec_cmd, rubocop_cmd. Ensures `bundle exec` is always used in Bundler-managed projects (handles transitive dependencies correctly).
+
+#### Discover/Rewrite Rules
+
+```
+rake test           → rtk rake test
+bundle exec rake    → rtk rake test
+rails test          → rtk rake test
+bin/rails test      → rtk rake test
+bundle exec rspec   → rtk rspec
+bundle exec rubocop → rtk rubocop
+bundle install      → rtk bundle install
+```
+
+ENV_PREFIX auto-strips `RAILS_ENV`, `WITH_COVERAGE`, `BUNDLE_GEMFILE` and re-prepends to the rewritten command.
+
 ### Format Strategy Decision Tree
 
 ```

CHANGELOG.md

@@ -5,6 +5,18 @@ All notable changes to rtk (Rust Token Killer) will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Features
+
+* **ruby:** add RSpec test runner filter with JSON parsing and text fallback (60%+ reduction)
+* **ruby:** add RuboCop linter filter with JSON parsing, grouped by cop/severity (60%+ reduction)
+* **ruby:** add minitest filter for `rake test` / `rails test` with state machine parser (85-90% reduction)
+* **ruby:** add TOML filter for `bundle install/update` — strip "Using" lines (70% reduction)
+* **ruby:** add `ruby_exec()` shared utility for auto-detecting `bundle exec` when Gemfile exists
+* **ruby:** add discover/rewrite rules for rake, rails, rspec, rubocop, and bundle commands
+>>>>>>> d78401b (docs(ruby): update CLAUDE.md module table and fork features)
+
 ## [0.30.1](https://github.com/rtk-ai/rtk/compare/v0.30.0...v0.30.1) (2026-03-18)
 
 

CLAUDE.md

@@ -230,8 +230,11 @@ rtk gain --history | grep proxy
 | pip_cmd.rs | pip/uv package manager | JSON parsing, auto-detect uv (70-85% reduction) |
 | go_cmd.rs | Go commands | NDJSON for test, text for build/vet (80-90% reduction) |
 | golangci_cmd.rs | golangci-lint | JSON parsing, group by rule (85% reduction) |
+| rake_cmd.rs | Minitest via rake/rails test | Failures only, summary line (85-90% reduction) |
+| rspec_cmd.rs | RSpec test runner | JSON parsing, failures only (60%+ JSON, 30%+ text fallback) |
+| rubocop_cmd.rs | RuboCop linter | JSON parsing, group by cop name (60%+ reduction) |
 | tee.rs | Full output recovery | Save raw output to file on failure, print hint for LLM re-read |
-| utils.rs | Shared utilities | Package manager detection, common formatting |
+| utils.rs | Shared utilities | Package manager detection, ruby_exec, common formatting |
 | discover/ | Claude Code history analysis | Scan JSONL sessions, classify commands, report missed savings |
 
 ## Performance Constraints
@@ -392,6 +395,15 @@ pub fn execute_with_filter(cmd: &str, args: &[&str]) -> Result<()> {
 - **Architecture**: Standalone Python commands (mirror lint/prettier), Go sub-enum (mirror git/cargo)
 - **Patterns**: JSON for structured output (ruff check, golangci-lint, pip), NDJSON streaming (go test), text state machine (pytest), text filters (go build/vet, ruff format)
 
+### Ruby on Rails Support (2026-03-15)
+- **Ruby Commands**: 3 modules for Ruby/Rails development
+  - `rtk rake test`: Minitest filter via rake/rails test, state machine parser (85-90% reduction)
+  - `rtk rspec`: RSpec test runner with JSON parsing, text fallback (60%+ reduction)
+  - `rtk rubocop`: RuboCop linter with JSON parsing, group by cop/severity (60%+ reduction)
+- **TOML Filter**: `bundle-install.toml` for bundle install/update (strips Using lines, 70% reduction)
+- **Shared Infrastructure**: `ruby_exec()` in utils.rs auto-detects `bundle exec` when Gemfile exists
+- **Hook Integration**: Rewrites `rake test`, `rails test`, `bundle exec` variants, `bin/rails test`
+
 ## Testing Strategy
 
 ### TDD Workflow (mandatory)

README.md

@@ -50,8 +50,11 @@ rtk filters and compresses command outputs before they reach your LLM context. S
 | `ruff check` | 3x | 3,000 | 600 | -80% |
 | `pytest` | 4x | 8,000 | 800 | -90% |
 | `go test` | 3x | 6,000 | 600 | -90% |
+| `rake test` | 4x | 6,000 | 600 | -90% |
+| `rspec` | 3x | 4,500 | 1,800 | -60% |
+| `rubocop` | 3x | 3,000 | 1,200 | -60% |
 | `docker ps` | 3x | 900 | 180 | -80% |
-| **Total** | | **~118,000** | **~23,900** | **-80%** |
+| **Total** | | **~131,500** | **~27,500** | **-79%** |
 
 > Estimates based on medium-sized TypeScript/Rust projects. Actual savings vary by project size.
 
@@ -171,6 +174,8 @@ rtk playwright test             # E2E results (failures only)
 rtk pytest                      # Python tests (-90%)
 rtk go test                     # Go tests (NDJSON, -90%)
 rtk cargo test                  # Cargo tests (-90%)
+rtk rake test                   # Ruby minitest (-90%)
+rtk rspec                       # RSpec tests (JSON, -60%+)
 ```
 
 ### Build & Lint
@@ -184,13 +189,15 @@ rtk cargo build                 # Cargo build (-80%)
 rtk cargo clippy                # Cargo clippy (-80%)
 rtk ruff check                  # Python linting (JSON, -80%)
 rtk golangci-lint run           # Go linting (JSON, -85%)
+rtk rubocop                     # Ruby linting (JSON, -60%+)
 ```
 
 ### Package Managers
 ```bash
 rtk pnpm list                   # Compact dependency tree
 rtk pip list                    # Python packages (auto-detect uv)
 rtk pip outdated                # Outdated packages
+rtk bundle install              # Ruby gems (strip Using lines)
 rtk prisma generate             # Schema generation (no ASCII art)
 ```
 
@@ -351,6 +358,10 @@ cp hooks/opencode-rtk.ts ~/.config/opencode/plugins/rtk.ts
 | `pip list/install` | `rtk pip ...` |
 | `go test/build/vet` | `rtk go ...` |
 | `golangci-lint` | `rtk golangci-lint` |
+| `rake test` / `rails test` | `rtk rake test` |
+| `bundle exec rspec` | `rtk rspec` |
+| `bundle exec rubocop` | `rtk rubocop` |
+| `bundle install/update` | `rtk bundle ...` |
 | `docker ps/images/logs` | `rtk docker ...` |
 | `kubectl get/logs` | `rtk kubectl ...` |
 | `curl` | `rtk curl` |