Agentlog

Agentlog is a Rails gem that adds a second development/test log optimized for coding agents.

It does not replace log/development.log. It writes a separate compact log that preserves the important request story while aggressively shrinking token-heavy details like params, job args, and repetitive SQL noise.

• One compact REQ line per controller request
• Optional grouped SQL lines for repeated or slow queries
• Optional JOB lines for enqueues that happen during the request
• Optional ERR lines when the request raises

By default it:

• writes to log/agent.log
• enables itself only in development and test
• keeps params on, but reduces values to type and size markers
• hides scalar values unless you explicitly preserve specific keys
• ignores arbitrary app log lines

Add the gem to your Rails app:

gem "agentlog"

Then bundle:

bundle install

Agentlog auto-installs through a Railtie in development and test.

You can override defaults in an initializer:

# config/initializers/agentlog.rb
Rails.application.config.agentlog.enabled = Rails.env.development? || Rails.env.test?
Rails.application.config.agentlog.path = "log/agent.log"
Rails.application.config.agentlog.log_params = true
Rails.application.config.agentlog.log_sql = true
Rails.application.config.agentlog.log_jobs = true
Rails.application.config.agentlog.preserve_keys = %w[user_id task_id request_id]
Rails.application.config.agentlog.repeat_sql_threshold = 3
Rails.application.config.agentlog.slow_sql_ms = 25.0

10:48:01 REQ POST /api/v1/app_events -> 202 8.0ms ctrl=api/v1/app_events#create fmt=json params={events:[{platform:str(3),app_version:str(3),session_id:str(36),event_name:str(12),properties:{active_task_count:int,variant:str(6)},+2} x8],device_id:str(36),app_event:{device_id:str(36)}} db=3.4ms/4q view=0.1ms gc=0.0ms
10:48:01 SQL NotificationToken_Load x3 1.5ms
10:48:01 JOB enqueue IngestAppEventsJob queue=default args=["E12AB6BE-8CB7-48A8-9972-1F52DD56C527",[{platform:str(3),app_version:str(3),session_id:str(36),event_name:str(39),properties:{error:str(142)},+1} x8],4239]

If you want a few debugging IDs to stay visible, list their keys in preserve_keys.

Rails.application.config.agentlog.preserve_keys = %w[user_id device_id task_id]

That changes values for those keys from compact markers like str(36) to truncated literals.

0.9.0 is intentionally narrow:

• Rails 8+
• dev/test only
• request-centric logging
• no attempt to compact arbitrary Rails.logger.info(...) strings

bundle exec rspec

MIT