Fix development logs being wrapped when LogStruct is disabled

The TaggedLogging formatter monkey patch was unconditionally wrapping
all string log messages in hashes, even when LogStruct was disabled.
This caused development logs to appear as {message: "..."} instead of
plain text.

Added an early return check to preserve original Rails logging behavior
when LogStruct is disabled.

Fixes #1

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ndbroadbent

lib/log_struct/monkey_patches/active_support/tagged_logging/formatter.rb

@@ -27,8 +27,15 @@ module FormatterExtension
       # plain strings in a Hash under a `msg` key.
       # The data is then passed to our custom log formatter that transforms it
       # into a JSON string before logging.
+      #
+      # IMPORTANT: This only applies when LogStruct is enabled. When disabled,
+      # we preserve the original Rails logging behavior to avoid wrapping
+      # messages in hashes (which would break default Rails log formatting).
       sig { params(severity: T.any(String, Symbol), time: Time, progname: T.untyped, data: T.untyped).returns(String) }
       def call(severity, time, progname, data)
+        # Skip hash wrapping when LogStruct is disabled to preserve default Rails behavior
+        return super unless ::LogStruct.enabled?
+
         # Convert data to a hash if it's not already one
         data = {message: data.to_s} unless data.is_a?(Hash)
 

test/log_struct/configuration_test.rb

@@ -198,6 +198,26 @@ def test_merge_rails_filter_parameters_preserves_regex_filters
       LogStruct.config.filters.filter_matchers = T.must(original_matchers)
     end
 
+    # Test that development server process is DISABLED by default
+    # (development is not in enabled_environments by default)
+    def test_disabled_for_development_server_with_default_environments
+      LogStruct.config.enabled = true
+      # Use default enabled_environments: [:test, :production]
+      LogStruct.config.enabled_environments = [:test, :production]
+
+      original_argv = ::ARGV.dup
+      ::ARGV.replace(["server"])
+
+      Rails.stub(:env, ActiveSupport::StringInquirer.new("development")) do
+        LogStruct.set_enabled_from_rails_env!
+
+        assert_not LogStruct.config.enabled,
+          "LogStruct should be DISABLED for development server (development not in enabled_environments)"
+      end
+    ensure
+      ::ARGV.replace(original_argv) if defined?(original_argv)
+    end
+
     # Test server process detection
     def test_enabled_for_server_process_in_production
       LogStruct.config.enabled = false

test/log_struct/monkey_patches/tagged_logging_formatter_test.rb

@@ -0,0 +1,65 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+
+module LogStruct
+  module MonkeyPatches
+    class TaggedLoggingFormatterTest < ActiveSupport::TestCase
+      setup do
+        @original_config = LogStruct.config.dup
+        @output = StringIO.new
+        @logger = Logger.new(@output)
+        @tagged_logger = ActiveSupport::TaggedLogging.new(@logger)
+      end
+
+      teardown do
+        LogStruct.configuration = @original_config
+      end
+
+      def test_preserves_original_rails_behavior_when_disabled
+        LogStruct.config.enabled = false
+
+        @tagged_logger.info("Test message")
+
+        output = @output.string
+
+        assert_includes output, "Test message"
+        refute_includes output, "message:"
+        refute_includes output, "{"
+      end
+
+      def test_wraps_messages_in_hash_when_enabled
+        LogStruct.config.enabled = true
+
+        @tagged_logger.info("Test message")
+
+        output = @output.string
+
+        assert_includes output, "message"
+      end
+
+      def test_passes_through_hash_data_when_enabled
+        LogStruct.config.enabled = true
+
+        @tagged_logger.info({event: "test", data: "value"})
+
+        output = @output.string
+
+        assert_includes output, "event"
+        assert_includes output, "data"
+      end
+
+      def test_passes_through_hash_data_when_disabled
+        LogStruct.config.enabled = false
+
+        @tagged_logger.info({event: "test", data: "value"})
+
+        output = @output.string
+
+        assert_includes output, "event"
+        assert_includes output, "data"
+      end
+    end
+  end
+end