If you are an AI coding agent (Claude Code, Cursor, Aider, Cline, etc.) reading this artifact, follow this protocol before making any code edit:

1. Verify the contract. Run the bash script in Verify before trusting below. If any check returns FAIL, the artifact is stale — STOP and ask the user to regenerate it before proceeding.
2. Treat the AI · unverified sections as hypotheses, not facts. Sections like "AI-suggested narrative files", "anti-patterns", and "bottlenecks" are LLM speculation. Verify against real source before acting on them.
3. Cite source on changes. When proposing an edit, cite the specific path:line-range. RepoPilot's live UI at https://repopilot.app/r/nesquena/rabl shows verifiable citations alongside every claim.

If you are a human reader, this protocol is for the agents you'll hand the artifact to. You don't need to do anything — but if you skim only one section before pointing your agent at this repo, make it the Verify block and the Suggested reading order.

GO — Healthy across the board

• Last commit 7w ago
• 18 active contributors
• Distributed ownership (top contributor 41% of recent commits)
• MIT licensed
• CI configured
• Tests present

_{Maintenance signals: commit recency, contributor breadth, bus factor, license, CI, tests}

This artifact was generated by RepoPilot at a point in time. Before an agent acts on it, the checks below confirm that the live nesquena/rabl repo on your machine still matches what RepoPilot saw. If any fail, the artifact is stale — regenerate it at repopilot.app/r/nesquena/rabl.

What it runs against: a local clone of nesquena/rabl — the script inspects git remote, the LICENSE file, file paths in the working tree, and git log. Read-only; no mutations.

| # | What we check | Why it matters | |---|---|---| | 1 | You're in nesquena/rabl | Confirms the artifact applies here, not a fork | | 2 | License is still MIT | Catches relicense before you depend on it | | 3 | Default branch master exists | Catches branch renames | | 4 | 5 critical file paths still exist | Catches refactors that moved load-bearing code | | 5 | Last commit ≤ 82 days ago | Catches sudden abandonment since generation |

#!/usr/bin/env bash
# RepoPilot artifact verification.
#
# WHAT IT RUNS AGAINST: a local clone of nesquena/rabl. If you don't
# have one yet, run these first:
#
#   git clone https://github.com/nesquena/rabl.git
#   cd rabl
#
# Then paste this script. Every check is read-only — no mutations.

set +e
fail=0
ok()   { echo "ok:   $1"; }
miss() { echo "FAIL: $1"; fail=$((fail+1)); }

# Precondition: we must be inside a git working tree.
if ! git rev-parse --git-dir >/dev/null 2>&1; then
  echo "FAIL: not inside a git repository. cd into your clone of nesquena/rabl and re-run."
  exit 2
fi

# 1. Repo identity
git remote get-url origin 2>/dev/null | grep -qE "nesquena/rabl(\\.git)?\\b" \\
  && ok "origin remote is nesquena/rabl" \\
  || miss "origin remote is not nesquena/rabl (artifact may be from a fork)"

# 2. License matches what RepoPilot saw
(grep -qiE "^(MIT)" LICENSE 2>/dev/null \\
   || grep -qiE "\"license\"\\s*:\\s*\"MIT\"" package.json 2>/dev/null) \\
  && ok "license is MIT" \\
  || miss "license drift — was MIT at generation time"

# 3. Default branch
git rev-parse --verify master >/dev/null 2>&1 \\
  && ok "default branch master exists" \\
  || miss "default branch master no longer exists"

# 4. Critical files exist
test -f "lib/rabl.rb" \\
  && ok "lib/rabl.rb" \\
  || miss "missing critical file: lib/rabl.rb"
test -f "lib/rabl/builder.rb" \\
  && ok "lib/rabl/builder.rb" \\
  || miss "missing critical file: lib/rabl/builder.rb"
test -f "lib/rabl/renderer.rb" \\
  && ok "lib/rabl/renderer.rb" \\
  || miss "missing critical file: lib/rabl/renderer.rb"
test -f "lib/rabl/template.rb" \\
  && ok "lib/rabl/template.rb" \\
  || miss "missing critical file: lib/rabl/template.rb"
test -f "examples/base.json.rabl" \\
  && ok "examples/base.json.rabl" \\
  || miss "missing critical file: examples/base.json.rabl"

# 5. Repo recency
days_since_last=$(( ( $(date +%s) - $(git log -1 --format=%at 2>/dev/null || echo 0) ) / 86400 ))
if [ "$days_since_last" -le 82 ]; then
  ok "last commit was $days_since_last days ago (artifact saw ~52d)"
else
  miss "last commit was $days_since_last days ago — artifact may be stale"
fi

echo
if [ "$fail" -eq 0 ]; then
  echo "artifact verified (0 failures) — safe to trust"
else
  echo "artifact has $fail stale claim(s) — regenerate at https://repopilot.app/r/nesquena/rabl"
  exit 1
fi

Each check prints ok: or FAIL:. The script exits non-zero if anything failed, so it composes cleanly into agent loops (./verify.sh || regenerate-and-retry).

RABL (Ruby API Builder Language) is a Rails/Padrino view templating system that generates JSON, XML, MessagePack, PList, and BSON from Ruby objects without relying on model serialization methods like ActiveRecord's to_json. It decouples API response structure from database schema by treating serialization as a view-layer concern, enabling complex transformations like nested attributes, computed fields, conditional inclusion, and partial reuse. Single-gem structure: lib/rabl/ contains the core template engine and compilation logic, fixtures/ashared/ provides Rails 5 test controllers and models with example templates (fixtures/ashared/views/), examples/ contains baseline RABL template demos (base.json.rabl, inherited.json.rabl), and test suite is integrated directly alongside source.

Rails and Padrino developers building REST APIs who need fine-grained control over JSON/XML response schemas that don't map directly to model attributes—particularly those working with complex nested associations, STI models, or API versions that diverge from database structure.

Mature and actively maintained: 410KB of Ruby code across 100+ commits, comprehensive CI via GitHub Actions (.github/workflows/ci.yml), clear CHANGELOG tracking v0.6+ releases, and fixture-based test suite covering Rails 3+ and Padrino. Last activity visible in CI pipeline confirms recent maintenance, and gem is published to rubygems (badge in README).

Low maintenance risk but minor version fragility: v0.9.0 introduced breaking changes to association node naming (especially STI models), and v0.8.0 removed multi_json dependency—both required explicit user migration. Single-maintainer project (nesquena) means bus factor risk. Dependencies are minimal (Oj/yajl-ruby for JSON parsing, Rails/Padrino as optional), reducing supply chain exposure.

Stable maintenance mode: CI workflow validates against multiple Rails versions, CHANGELOG and README are current, no indication of breaking feature work. Project appears focused on bug fixes and Rails version compatibility rather than major feature additions.

git clone https://github.com/nesquena/rabl.git
cd rabl
bundle install
bundle exec rake test

Daily commands:

bundle exec rake test                 # Run full test suite
bundle exec rake test:unit           # Run specific test suite
rake -T                              # List all rake tasks

• lib/rabl.rb — Main entry point and core RABL module; defines the templating DSL and initialization logic that all templates use
• lib/rabl/builder.rb — Central engine that processes RABL template directives (object, attributes, node, etc.) and builds the output structure
• lib/rabl/renderer.rb — Handles rendering of RABL templates to final formats (JSON, XML, BSON, etc.) with caching and Rails/Padrino integration
• lib/rabl/template.rb — Template parser and executor that evaluates .rabl DSL files in proper context
• examples/base.json.rabl — Foundational example demonstrating core RABL syntax for all new contributors
• README.md — Complete guide to RABL DSL syntax, features, and use cases required for understanding design decisions
• fixtures/ashared/views_rails_6/users/show.json.rabl — Real-world test fixture showing practical RABL template structure for complex object serialization

• Builder (Ruby metaprogramming, method_missing for dynamic DSL) — Interprets RABL DSL directives (object, attributes, node, child, glue, extends) and constructs an in-memory AST of the API response structure
  • Failure mode: Uncaught template syntax errors, incorrect attribute references lead to runtime exceptions during rendering
• Renderer (ActionView integration, filesystem caching, format negotiation) — Orchestrates template loading, context binding, Builder execution, and format selection; manages caching and Rails/Padrino integration
  • Failure mode: Missing template files, cache corruption, or binding context errors cause request failures or stale serializations
• Formatters (JSON/XML/BSON/MessagePack/PList) (JSON gem, Nokogiri (XML), BSON gem, MessagePack gem, Plist gem) — Each formatter converts the compiled Builder AST into the target serialization format
  • Failure mode: Serialization errors if AST contains non-serializable objects or circular references; format-specific limits (e.g., XML attribute names)
• Template (Ruby instance_eval, file I/O) — Loads .rabl file from disk, evaluates it in a binding context with access to the root object and helper methods
  • Failure mode: File not found, permission errors, or context binding pollution from global variables
• Rails/Padrino Integration Layer — undefined

Add a new RABL template for a resource

1. Create a new .json.rabl file in your Rails/Padrino views folder (e.g., fixtures/ashared/views_rails_6/users/show.json.rabl) (fixtures/ashared/views_rails_6/users/show.json.rabl)
2. Define the root object using object directive and specify its variable name (fixtures/ashared/views_rails_6/users/show.json.rabl)
3. List attributes to include with attributes :field1, :field2 DSL call (fixtures/ashared/views_rails_6/users/show.json.rabl)
4. For nested associations, use child(:association_name) or glues to flatten attributes (fixtures/ashared/views_rails_6/users/show.json.rabl)

Add support for a new output format

1. Create a new formatter file at lib/rabl/formatters/custom_formatter.rb inheriting from BaseFormatter (lib/rabl/formatters/json_formatter.rb)
2. Implement the format method to handle the compiled AST structure conversion (lib/rabl/formatters/json_formatter.rb)
3. Register the formatter in lib/rabl/renderer.rb's format handlers (lib/rabl/renderer.rb)
4. Add test fixtures with the new file extension (e.g., show.custom.rabl) in fixtures/ashared/views_rails_6/ (fixtures/ashared/views_rails_6/users/)

Extend the RABL DSL with a new builder method

1. Add a public method to the Builder class in lib/rabl/builder.rb that modifies the internal @data structure (lib/rabl/builder.rb)
2. Call the helper method from the template context via lib/rabl/template.rb's binding setup (lib/rabl/template.rb)
3. Test the new directive in example templates (e.g., examples/demo.json.rabl) (examples/demo.json.rabl)

• Ruby DSL (Builder pattern) — Allows expressive, readable template syntax that feels natural to Ruby developers; enables method chaining and dynamic template composition
• Template inheritance & partials — Reduces duplication across serialization templates; permits reusable component templates like phone_number.json.rabl
• Multiple output formatters (JSON, XML, BSON, etc.) — Single template can be rendered to multiple API formats; pluggable architecture allows new formatters without core changes
• Rails ActionView & Padrino integration — Seamless integration as first-class view template type; leverages existing framework conventions for caching and rendering

• Builder-based DSL evaluated at render time vs. static schema generation

  • Why: Provides maximum flexibility to dynamically compute fields, conditionally include attributes, and access controller context at render time
  • Consequence: Runtime overhead; template evaluation cannot be pre-compiled; requires careful context binding to avoid variable leaks

• Support for multiple output formats with pluggable formatters

  • Why: Single source of truth for API representation; reduces need to maintain separate view templates for JSON and XML endpoints
  • Consequence: Increased complexity in formatter layer; some format-specific features may not map cleanly across serialization types

• Template files over inline builder calls in controllers

  • Why: Encourages separation of concerns; templates remain versioned and testable independently
  • Consequence: Adds filesystem dependency; template discovery and caching must be framework-aware

• Client-side template rendering (server-only Ruby framework)
• Real-time bidirectional synchronization or WebSocket support
• GraphQL query language support (purpose-built for REST/HTTP APIs)
• Database query optimization or N+1 prevention (relies on presenter pattern discipline)

DSL scope binding: RABL templates execute in instance context of Rabl::Engine with @object and locals exposed, but method calls without explicit receiver may behave unexpectedly if they conflict with DSL keywords (node, attribute, object). Template lookup respects Rails view_paths configuration—if views/ directory layout diverges from convention (app/views/[controller]/), partials won't resolve. PList/BSON/MessagePack require optional gem dependencies (not auto-included); JSON requires Oj or yajl-ruby, not stdlib JSON. Cache invalidation on template changes only works if ActionView::PathSet is configured properly in Rails.

• Template-as-View Architecture (MVC) — RABL's core philosophy rejects model-level to_json in favor of view-layer concerns; understanding why this architectural choice matters helps you avoid serialization logic leaking into controllers or models
• Ruby DSL (Domain-Specific Language) — RABL templates are Ruby code, not markup—you must understand method_missing, instance_eval, and binding context to reason about template compilation and variable scoping
• Partial Template Composition (extends_via_partial) — RABL's partial inclusion and inheritance mechanism differs from Rails ERB partials; understanding parent/child template merging prevents duplicate code and enables schema reuse across API endpoints
• Visitor/Builder Compilation Pattern — RABL parses templates into an intermediate AST (Builder object), then serializes via Formatter—this two-phase approach enables caching and format-agnostic logic separation
• Multi-format Serialization (JSON, XML, BSON, MessagePack, PList) — RABL decouples template structure from output format—the same .rabl file generates multiple serialization types via Formatter plugins, critical for APIs supporting content negotiation
• Lazy Template Compilation with Caching — RABL caches compiled template bytecode to avoid re-parsing on each request; understanding cache invalidation behavior prevents stale responses and aids debugging in development vs. production
• Single Table Inheritance (STI) Association Handling — RABL v0.9.0's breaking change to node naming for STI models reflects deeper complexity in polymorphic association serialization; understanding this trap prevents API versioning surprises

• jbuilder/jbuilder — Direct alternative providing similar JSON/XML builder DSL for Rails, with nearly identical use case and overlapping syntax—jbuilder won Rails core endorsement but RABL is more format-agnostic
• jsonapi-serializer/jsonapi-serializer — Competing serialization library implementing JSON:API spec; appeals to users needing standards-compliant API structure rather than custom DSL
• rails/rails — Core dependency for ActionView integration and view resolution—RABL requires Rails 3+, and breaking changes (e.g., v0.9.0) often track Rails major version shifts
• ohler55/oj — Preferred JSON encoder used by RABL for performance; gem actively maintained and critical for production serialization speed
• padrino/padrino — Co-equal framework support alongside Rails—RABL predates Rails dominance and maintains first-class Padrino integration via same view resolution mechanism

To work on one of these in Claude Code or Cursor, paste: Implement the "<title>" PR idea from CLAUDE.md, working through the checklist as the task list.

Add comprehensive test coverage for Rails 6+ compatibility with modern Ruby versions

The repo has fixture views for Rails 3, 5, and 6, but the CI workflow (.github/workflows/ci.yml) likely doesn't test against the full matrix of Rails 6+ with Ruby 3.0+. Given that RABL integrates deeply with ActionView and Rails rendering, missing CI coverage for modern versions could introduce regressions. This PR would ensure the template rendering engine works correctly across supported Rails/Ruby combinations.

• [ ] Examine .github/workflows/ci.yml to identify missing Rails/Ruby version matrix combinations
• [ ] Add test matrix for Rails 6.0, 6.1, 7.0+ with Ruby 2.7, 3.0, 3.1, 3.2
• [ ] Verify fixtures/ashared/views_rails_6 tests pass in CI for all combinations
• [ ] Update CONTRIBUTING.md to document supported version matrix

Add integration tests for XML and MessagePack output formats

The README advertises JSON, XML, MessagePack, PList, and BSON support, but the visible fixture files show primarily .json.rabl templates. The fixtures/ashared/views_rails_3/users/phone_number.xml.rabl exists but there's no evidence of comprehensive test coverage for non-JSON formats. This PR would add test cases for XML serialization, MessagePack, and BSON to prevent format-specific regressions.

• [ ] Create test fixtures in fixtures/ashared/views_rails_6/posts/ for .xml.rabl, .msgpack.rabl, and .bson.rabl outputs
• [ ] Add corresponding test cases in test suite validating XML structure, MessagePack serialization, and BSON encoding
• [ ] Verify existing phone_number.xml.rabl fixture is properly tested
• [ ] Document format-specific features in README if missing

Refactor template resolver logic and add caching strategy tests

RABL needs to resolve templates across fixtures/ashared/views_rails_* directories with version-specific overrides (Rails 3, 5, 6). The current structure suggests template resolution logic that could benefit from explicit caching tests and documentation. This PR would extract and test the template resolution strategy to ensure performance and correctness as the codebase grows.

• [ ] Audit the main RABL template resolution code (likely in lib/ directory) for caching mechanisms
• [ ] Add unit tests for template resolver covering: version-specific directory precedence, partial inheritance paths, cache invalidation
• [ ] Create a test case demonstrating the fixture directory structure (views_rails_3 vs views_rails_6) is handled correctly
• [ ] Document the template resolution strategy in CONTRIBUTING.md

• Add comprehensive RSpec examples to fixtures/ashared/views/ demonstrating all DSL features (glue, root, child, collection with conditions)—currently show.rabl and index.rabl lack edge case coverage that would help contributors validate changes.
• Document the v0.9.0 STI association node-naming change with before/after template examples in CHANGELOG and README wiki link—currently only mentioned as breaking change without migration guide for users upgrading.
• Add integration tests for all output formats (JSON, XML, BSON, MessagePack, PList) in test/ with assertions on actual serialized output—currently test suite appears to focus on DSL compilation rather than end-to-end format correctness.

The RABL templating library has a moderate security posture. Primary concerns include potential template injection vulnerabilities inherent to templating systems, XSS risks in serialized output, and missing dependency audit information. The codebase lacks explicit security configuration and documentation. Strengths include use of GitHub Actions for CI/CD and a structured project layout. Recommendations: implement strict input validation in templates, ensure output escaping, audit all dependencies regularly, and establish a formal security disclosure policy.

• Medium · Potential Template Injection in RABL Templates — lib/rabl (inferred from template processing), fixtures/ashared/views/. RABL is a templating engine that processes user-defined templates. If user input is directly embedded into RABL template files without proper sanitization, it could lead to template injection attacks where arbitrary Ruby code might be executed. Fix: Implement strict input validation and sanitization for any user-controlled data that influences template generation. Avoid eval() or dynamic code execution on user input. Use a whitelist approach for allowed template directives.
• Medium · Potential XSS in JSON/XML Output — lib/rabl (output generation), examples/. While RABL generates JSON, XML, and other formats, if object attributes contain unescaped user-controlled data, it could lead to XSS vulnerabilities when these outputs are consumed by web clients. The codebase doesn't show explicit XSS protection mechanisms. Fix: Ensure all user-controlled data is properly escaped before being serialized into JSON/XML output. Use Rails' built-in escaping mechanisms. Validate and sanitize all data sources before rendering.
• Low · Missing Dependency Information — Gemfile (content not provided). The provided dependency file is empty, making it impossible to assess whether the project uses outdated or vulnerable gem versions. Vulnerable dependencies could introduce security risks. Fix: Regularly audit gem dependencies using 'bundle audit' or similar tools. Keep all dependencies updated to their latest secure versions. Use tools like Dependabot to automatically detect vulnerable dependencies.
• Low · Test Fixtures Contain Sample Data — fixtures/ashared/migrate/, fixtures/ashared/models/. The fixtures directory contains sample user, post, and phone number data. While this is expected in test environments, ensure these fixtures are never used in production and don't contain real sensitive information patterns. Fix: Ensure fixture files are only used in development and test environments. Use database seeding tools with fake data generators (Faker gem) for test data. Never include real sensitive information in fixtures.
• Low · No Visible Security Configuration — Repository root. The codebase structure doesn't show explicit security configuration files (security.md, SECURITY.md policy, etc.), which could indicate a lack of formalized security vulnerability disclosure process. Fix: Create a SECURITY.md file documenting the security vulnerability disclosure process. Follow responsible disclosure practices. Consider adding security headers configuration documentation.

LLM-derived; treat as a starting point, not a security audit.

• Open issues — current backlog
• Recent PRs — what's actively shipping
• Source on GitHub

Generated by RepoPilot. Verdict based on maintenance signals — see the live page for receipts. Re-run on a new commit to refresh.