diff --git a/app/web/boot/setup.rb b/app/web/boot/setup.rb
index fd69faa8..edb5687d 100644
--- a/app/web/boot/setup.rb
+++ b/app/web/boot/setup.rb
@@ -13,6 +13,7 @@ class << self
           def call!
             validate_environment!
             configure_request_service!
+            configure_runtime_logging!
           end
 
           private
@@ -28,6 +29,13 @@ def validate_environment!
           def configure_request_service!
             nil
           end
+
+          # @return [void]
+          def configure_runtime_logging!
+            return unless defined?(Rack::Timeout::Logger)
+
+            Rack::Timeout::Logger.logger = AppLogger.logger
+          end
         end
       end
     end
diff --git a/app/web/config/environment_validator.rb b/app/web/config/environment_validator.rb
index 36f0b18e..4d80ee1a 100644
--- a/app/web/config/environment_validator.rb
+++ b/app/web/config/environment_validator.rb
@@ -49,12 +49,17 @@ def auto_source_enabled?
 
         def set_development_key
           ENV['HTML2RSS_SECRET_KEY'] = 'development-default-key-not-for-production'
-          puts '⚠️  WARNING: Using default secret key for development/testing only!'
-          puts '   Set HTML2RSS_SECRET_KEY environment variable for production use.'
+          log_development_default_secret_key_warning
+          warn_lines(
+            'WARNING: Using default secret key for development/testing only!',
+            'Set HTML2RSS_SECRET_KEY environment variable for production use.'
+          )
+          nil
         end
 
         def show_production_error
-          puts production_error_message
+          SecurityLogger.log_config_validation_failure('secret_key', 'Missing required secret key')
+          warn_lines(*production_error_message.lines(chomp: true))
           exit 1
         end
 
@@ -79,9 +84,11 @@ def validate_secret_key!
           return unless secret == 'your-generated-secret-key-here' || secret.length < 32
 
           SecurityLogger.log_config_validation_failure('secret_key', 'Invalid or weak secret key')
-          puts '❌ CRITICAL: Invalid secret key for production deployment!'
-          puts '   Secret key must be at least 32 characters and not the default placeholder.'
-          puts '   Generate a secure key: openssl rand -hex 32'
+          warn_lines(
+            'CRITICAL: Invalid secret key for production deployment!',
+            'Secret key must be at least 32 characters and not the default placeholder.',
+            'Generate a secure key: openssl rand -hex 32'
+          )
           exit 1
         end
 
@@ -90,11 +97,35 @@ def validate_account_configuration!
           weak_tokens = accounts.select { |acc| acc[:token].length < 16 }
           return unless weak_tokens.any?
 
+          handle_weak_account_tokens!(weak_tokens)
+        end
+
+        # @param lines [Array<String>]
+        # @return [void]
+        def warn_lines(*lines)
+          lines.each { |line| Kernel.warn(line) }
+          nil
+        end
+
+        # @return [void]
+        def log_development_default_secret_key_warning
+          SecurityLogger.log_config_validation_failure(
+            'secret_key',
+            'Using development default secret key',
+            severity: :warn
+          )
+        end
+
+        # @param weak_tokens [Array<Hash{Symbol=>String}>]
+        # @return [void]
+        def handle_weak_account_tokens!(weak_tokens)
           weak_usernames = weak_tokens.map { |acc| acc[:username] }.join(', ')
           SecurityLogger.log_config_validation_failure('account_tokens', "Weak tokens for users: #{weak_usernames}")
-          puts '❌ CRITICAL: Weak authentication tokens detected in production!'
-          puts '   All tokens must be at least 16 characters long.'
-          puts "   Weak tokens found for users: #{weak_usernames}"
+          warn_lines(
+            'CRITICAL: Weak authentication tokens detected in production!',
+            'All tokens must be at least 16 characters long.',
+            "Weak tokens found for users: #{weak_usernames}"
+          )
           exit 1
         end
       end
diff --git a/app/web/request/request_context_middleware.rb b/app/web/request/request_context_middleware.rb
index ad49ad75..61a18cf3 100644
--- a/app/web/request/request_context_middleware.rb
+++ b/app/web/request/request_context_middleware.rb
@@ -3,6 +3,7 @@
 require 'rack/request'
 require 'securerandom'
 require 'time'
+require_relative '../security/log_sanitizer'
 
 module Html2rss
   module Web
@@ -57,7 +58,7 @@ def build_context(request)
         path = request.path_info.to_s
         RequestContext::Context.new(
           request_id: request_id_for(request),
-          path: path,
+          path: LogSanitizer.sanitize_path(path),
           http_method: request.request_method.to_s.upcase,
           route_group: route_group_for(path),
           actor: nil,
diff --git a/app/web/security/log_sanitizer.rb b/app/web/security/log_sanitizer.rb
new file mode 100644
index 00000000..6d4ff23c
--- /dev/null
+++ b/app/web/security/log_sanitizer.rb
@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require 'digest'
+require 'html2rss/url'
+
+module Html2rss
+  module Web
+    ##
+    # Sanitizes request paths and log payloads before they are emitted.
+    module LogSanitizer
+      FEED_TOKEN_ROUTE = %r{\A(/api/v1/feeds/)([^/?]+?)(\.(?:json|xml|rss))?\z}
+
+      class << self
+        # @param path [String, nil]
+        # @return [String, nil]
+        def sanitize_path(path)
+          return if path.nil?
+
+          path.to_s.gsub(FEED_TOKEN_ROUTE, '\1[REDACTED]\3')
+        end
+
+        # @param details [Hash]
+        # @return [Hash]
+        def sanitize_details(details)
+          details.each_with_object({}) do |(key, value), sanitized|
+            sanitized[key] = sanitize_value(key, value)
+          end
+        end
+
+        private
+
+        # @param key [Object]
+        # @param value [Object]
+        # @return [Object]
+        def sanitize_value(key, value)
+          return sanitize_details(value) if value.is_a?(Hash)
+          return value.map { |entry| sanitize_value(key, entry) } if value.is_a?(Array)
+          return sanitize_url(value) if url_key?(key)
+
+          value
+        end
+
+        # @param key [Object]
+        # @return [Boolean]
+        def url_key?(key)
+          key_name = key.to_s
+          key_name == 'url' || key_name.end_with?('_url', '_urls')
+        end
+
+        # @param value [Object]
+        # @return [Hash{Symbol=>Object}, Object]
+        def sanitize_url(value)
+          url = value.to_s
+          return value if url.empty?
+
+          normalized_url = Html2rss::Url.for_channel(url)
+          {
+            host: normalized_url.host,
+            scheme: normalized_url.scheme,
+            hash: Digest::SHA256.hexdigest(url)[0..11]
+          }.compact
+        rescue StandardError
+          { hash: Digest::SHA256.hexdigest(url)[0..11] }
+        end
+      end
+    end
+  end
+end
diff --git a/app/web/security/security_logger.rb b/app/web/security/security_logger.rb
index 1d15d495..bc0fce99 100644
--- a/app/web/security/security_logger.rb
+++ b/app/web/security/security_logger.rb
@@ -1,9 +1,6 @@
 # frozen_string_literal: true
 
-require 'logger'
-require 'json'
 require 'digest'
-require 'time'
 module Html2rss
   module Web
     ##
@@ -11,16 +8,10 @@ module Web
     # Provides structured logging for security events to stdout
     module SecurityLogger
       class << self
-        # Initialize logger to stdout with structured JSON output
-        # @return [Logger]
-        def logger
-          Thread.current[:security_logger] ||= create_logger
-        end
-
-        # Reset logger (for testing)
+        # Reset shared logger state for tests.
         # @return [void]
         def reset_logger!
-          Thread.current[:security_logger] = nil
+          AppLogger.reset_logger!
         end
 
         ##
@@ -111,12 +102,13 @@ def log_blocked_request(ip, reason, endpoint)
         # Log configuration validation failure
         # @param component [String] component that failed validation
         # @param details [String] validation failure details
+        # @param severity [Symbol]
         # @return [void]
-        def log_config_validation_failure(component, details)
+        def log_config_validation_failure(component, details, severity: :error)
           log_event('config_validation_failure', {
                       component: component,
                       details: details
-                    }, severity: :error)
+                    }, severity: severity)
         end
 
         # Log lifecycle events for in-memory config/cache snapshots
@@ -134,32 +126,18 @@ def log_cache_lifecycle(component, event, details = {})
 
         private
 
-        def create_logger
-          Logger.new($stdout).tap do |log|
-            log.formatter = proc do |severity, datetime, _progname, msg|
-              "#{{
-                timestamp: datetime.iso8601,
-                level: severity,
-                service: 'html2rss-web',
-                **JSON.parse(msg, symbolize_names: true)
-              }.to_json}\n"
-            end
-          end
-        end
-
         ##
         # Log a security event
         # @param event_type [String] type of security event
         # @param data [Hash] event data
         def log_event(event_type, data, severity: :warn)
-          context_data = RequestContext.current_h
-          payload = {
-            security_event: event_type,
-            **context_data,
-            **data
-          }.to_json
-
-          logger.public_send(severity, payload)
+          LogEvent.emit(
+            level: severity,
+            payload: {
+              security_event: event_type,
+              details: data
+            }
+          )
         rescue StandardError => error
           handle_logging_error(error, event_type, data)
         end
@@ -170,8 +148,9 @@ def log_event(event_type, data, severity: :warn)
         # @param event_type [String] type of security event
         # @param data [Hash] event data
         def handle_logging_error(error, event_type, data)
-          Kernel.warn("Security logging error: #{error.message}")
-          Kernel.warn("Security event: #{event_type} - #{data}")
+          sanitized_data = LogSanitizer.sanitize_details(data)
+          Kernel.warn("Structured logging fallback: #{error.class}: #{error.message}")
+          Kernel.warn("component=security_logger security_event=#{event_type} details=#{sanitized_data}")
         end
       end
     end
diff --git a/app/web/telemetry/app_logger.rb b/app/web/telemetry/app_logger.rb
new file mode 100644
index 00000000..7281c5dc
--- /dev/null
+++ b/app/web/telemetry/app_logger.rb
@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+require 'json'
+require 'logger'
+require 'time'
+
+module Html2rss
+  module Web
+    ##
+    # Shared structured logger for application and middleware runtime events.
+    module AppLogger
+      class << self
+        # @return [Logger]
+        def logger
+          Thread.current[:app_logger] ||= build_logger
+        end
+
+        # @return [void]
+        def reset_logger!
+          Thread.current[:app_logger] = nil
+        end
+
+        private
+
+        # @return [Logger]
+        def build_logger
+          Logger.new($stdout).tap do |log|
+            log.formatter = method(:format_entry)
+          end
+        end
+
+        # @param severity [String]
+        # @param datetime [Time]
+        # @param _progname [String, nil]
+        # @param message [String]
+        # @return [String]
+        def format_entry(severity, datetime, _progname, message)
+          "#{base_payload(severity, datetime).merge(normalize_message(message)).to_json}\n"
+        end
+
+        # @param severity [String]
+        # @param datetime [Time]
+        # @return [Hash{Symbol=>Object}]
+        def base_payload(severity, datetime)
+          {
+            timestamp: datetime.iso8601,
+            level: severity,
+            service: 'html2rss-web'
+          }
+        end
+
+        # @param message [Object]
+        # @return [Hash{Symbol=>Object}]
+        def normalize_message(message)
+          message_string = message.to_s
+          return parsed_json(message_string) if json_like?(message_string)
+
+          parse_logfmt(message_string) || { message: message_string }
+        end
+
+        # @param message [String]
+        # @return [Hash{Symbol=>Object}, nil]
+        def parsed_json(message)
+          JSON.parse(message, symbolize_names: true)
+        rescue JSON::ParserError, TypeError
+          nil
+        end
+
+        # @param message [String]
+        # @return [Boolean]
+        def json_like?(message)
+          stripped = message.lstrip
+          stripped.start_with?('{', '[')
+        end
+
+        # @param message [String]
+        # @return [Hash{Symbol=>Object}, nil]
+        def parse_logfmt(message)
+          pairs = message.scan(/([a-zA-Z0-9_.-]+)=("[^"]*"|\S+)/)
+          return nil if pairs.empty?
+
+          pairs.to_h do |key, raw_value|
+            [key.to_sym, normalize_logfmt_value(raw_value)]
+          end
+        end
+
+        # @param raw_value [String]
+        # @return [String, Integer, Float, TrueClass, FalseClass]
+        def normalize_logfmt_value(raw_value)
+          value = raw_value.delete_prefix('"').delete_suffix('"')
+          return true if value == 'true'
+          return false if value == 'false'
+          return value.to_i if value.match?(/\A-?\d+\z/)
+          return value.to_f if value.match?(/\A-?\d+\.\d+\z/)
+
+          value
+        end
+      end
+    end
+  end
+end
diff --git a/app/web/telemetry/log_event.rb b/app/web/telemetry/log_event.rb
new file mode 100644
index 00000000..0b85a561
--- /dev/null
+++ b/app/web/telemetry/log_event.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Html2rss
+  module Web
+    ##
+    # Shared structured log emitter for request-scoped application events.
+    module LogEvent
+      class << self
+        # @param payload [Hash{Symbol=>Object}]
+        # @param level [Symbol]
+        # @return [void]
+        def emit(payload:, level: :info)
+          logger.public_send(level, build_payload(payload).to_json)
+        end
+
+        private
+
+        # @return [Logger]
+        def logger
+          AppLogger.logger
+        end
+
+        # @param payload [Hash{Symbol=>Object}]
+        # @return [Hash{Symbol=>Object}]
+        def build_payload(payload)
+          RequestContext.current_h.merge(LogSanitizer.sanitize_details(payload))
+        end
+      end
+    end
+  end
+end
diff --git a/app/web/telemetry/observability.rb b/app/web/telemetry/observability.rb
index 496a0c9b..78eaae1f 100644
--- a/app/web/telemetry/observability.rb
+++ b/app/web/telemetry/observability.rb
@@ -1,9 +1,5 @@
 # frozen_string_literal: true
 
-require 'json'
-require 'logger'
-require 'time'
-
 module Html2rss
   module Web
     ##
@@ -18,34 +14,20 @@ class << self
         # @param level [Symbol]
         # @return [void]
         def emit(event_name:, outcome:, details: {}, level: :info)
-          logger.public_send(level, build_payload(event_name, outcome, details).to_json)
+          LogEvent.emit(payload: build_payload(event_name, outcome, details), level: level)
         rescue StandardError => error
           handle_emit_error(error, event_name, outcome)
         end
 
         private
 
-        # @return [Logger]
-        def logger
-          Thread.current[:observability_logger] ||= Logger.new($stdout).tap do |log|
-            log.formatter = proc do |severity, datetime, _progname, msg|
-              "#{{
-                timestamp: datetime.iso8601,
-                level: severity,
-                service: 'html2rss-web',
-                **JSON.parse(msg, symbolize_names: true)
-              }.to_json}\n"
-            end
-          end
-        end
-
         # @param error [StandardError]
         # @param event_name [String]
         # @param outcome [String]
         # @return [void]
         def handle_emit_error(error, event_name, outcome)
-          Kernel.warn("Observability emit error: #{error.message}")
-          Kernel.warn("event_name=#{event_name} outcome=#{outcome}")
+          Kernel.warn("Structured logging fallback: #{error.class}: #{error.message}")
+          Kernel.warn("component=observability event_name=#{event_name} outcome=#{outcome}")
         end
 
         # @param event_name [String]
diff --git a/spec/html2rss/web/boot/setup_spec.rb b/spec/html2rss/web/boot/setup_spec.rb
index 8682dbce..c5c2461f 100644
--- a/spec/html2rss/web/boot/setup_spec.rb
+++ b/spec/html2rss/web/boot/setup_spec.rb
@@ -5,13 +5,13 @@
 require_relative '../../../../app'
 
 RSpec.describe Html2rss::Web::Boot::Setup do
-  describe '.call!' do
-    before do
-      allow(Html2rss::Web::EnvironmentValidator).to receive(:validate_environment!)
-      allow(Html2rss::Web::EnvironmentValidator).to receive(:validate_production_security!)
-      allow(Html2rss::Web::Flags).to receive(:validate!)
-    end
+  before do
+    allow(Html2rss::Web::EnvironmentValidator).to receive(:validate_environment!)
+    allow(Html2rss::Web::EnvironmentValidator).to receive(:validate_production_security!)
+    allow(Html2rss::Web::Flags).to receive(:validate!)
+  end
 
+  describe '.call!' do
     it 'validates environment state', :aggregate_failures do
       described_class.call!
 
@@ -19,5 +19,16 @@
       expect(Html2rss::Web::EnvironmentValidator).to have_received(:validate_production_security!).once
       expect(Html2rss::Web::Flags).to have_received(:validate!).once
     end
+
+    it 'routes rack-timeout logs through the shared app logger' do
+      stub_const('Rack::Timeout::Logger', Class.new)
+      logger_holder = { value: nil }
+      Rack::Timeout::Logger.define_singleton_method(:logger=) { |value| logger_holder[:value] = value }
+      Rack::Timeout::Logger.define_singleton_method(:logger) { logger_holder[:value] }
+
+      described_class.call!
+
+      expect(Rack::Timeout::Logger.logger).to be(Html2rss::Web::AppLogger.logger)
+    end
   end
 end
diff --git a/spec/html2rss/web/environment_validator_spec.rb b/spec/html2rss/web/environment_validator_spec.rb
index 0a5ed65e..fa7e0248 100644
--- a/spec/html2rss/web/environment_validator_spec.rb
+++ b/spec/html2rss/web/environment_validator_spec.rb
@@ -4,8 +4,60 @@
 require 'climate_control'
 
 require_relative '../../../app/web/config/environment_validator'
+require_relative '../../../app/web/config/flags'
+require_relative '../../../app/web/security/security_logger'
 
 RSpec.describe Html2rss::Web::EnvironmentValidator do
+  describe '.validate_environment!' do
+    it 'sets a development default secret key without exiting' do
+      allow(Html2rss::Web::SecurityLogger).to receive(:log_config_validation_failure)
+      allow(Kernel).to receive(:warn)
+
+      ClimateControl.modify('RACK_ENV' => 'development', 'HTML2RSS_SECRET_KEY' => nil) do
+        described_class.validate_environment!
+        expect(ENV.fetch('HTML2RSS_SECRET_KEY')).to eq('development-default-key-not-for-production')
+      end
+    end
+
+    it 'logs development default secret key warnings' do
+      allow(Html2rss::Web::SecurityLogger).to receive(:log_config_validation_failure)
+      allow(Kernel).to receive(:warn)
+
+      ClimateControl.modify('RACK_ENV' => 'development', 'HTML2RSS_SECRET_KEY' => nil) do
+        described_class.validate_environment!
+      end
+
+      expect(Html2rss::Web::SecurityLogger).to have_received(:log_config_validation_failure)
+        .with('secret_key', 'Using development default secret key', severity: :warn)
+    end
+
+    it 'logs missing production secret key failures before exiting' do
+      allow(Html2rss::Web::SecurityLogger).to receive(:log_config_validation_failure)
+      allow(Kernel).to receive(:warn)
+
+      ClimateControl.modify('RACK_ENV' => 'production', 'HTML2RSS_SECRET_KEY' => nil) do
+        expect { described_class.validate_environment! }.to raise_error(SystemExit)
+      end
+
+      expect(Html2rss::Web::SecurityLogger).to have_received(:log_config_validation_failure)
+        .with('secret_key', 'Missing required secret key')
+    end
+  end
+
+  describe '.validate_production_security!' do
+    it 'logs weak production secret keys before exiting' do
+      allow(Html2rss::Web::SecurityLogger).to receive(:log_config_validation_failure)
+      allow(Kernel).to receive(:warn)
+
+      ClimateControl.modify('RACK_ENV' => 'production', 'HTML2RSS_SECRET_KEY' => 'short-secret') do
+        expect { described_class.validate_production_security! }.to raise_error(SystemExit)
+      end
+
+      expect(Html2rss::Web::SecurityLogger).to have_received(:log_config_validation_failure)
+        .with('secret_key', 'Invalid or weak secret key')
+    end
+  end
+
   describe '.auto_source_enabled?' do
     context 'when in development' do
       it 'defaults to enabled when flag is not set' do
diff --git a/spec/html2rss/web/log_sanitizer_spec.rb b/spec/html2rss/web/log_sanitizer_spec.rb
new file mode 100644
index 00000000..b8653468
--- /dev/null
+++ b/spec/html2rss/web/log_sanitizer_spec.rb
@@ -0,0 +1,188 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'stringio'
+
+require_relative '../../../app/web/request/request_context'
+require_relative '../../../app/web/security/security_logger'
+require_relative '../../../app/web/telemetry/app_logger'
+require_relative '../../../app/web/telemetry/log_event'
+require_relative '../../../app/web/security/log_sanitizer'
+require_relative '../../../app/web/telemetry/observability'
+
+RSpec.describe Html2rss::Web::LogSanitizer do
+  let(:io) { StringIO.new }
+  let(:test_logger) { Logger.new(io).tap { |log| log.formatter = Html2rss::Web::AppLogger.send(:method, :format_entry) } }
+  let(:expected_news_url) do
+    {
+      host: 'news.ycombinator.com',
+      scheme: 'https',
+      hash: Digest::SHA256.hexdigest('https://news.ycombinator.com')[0..11]
+    }
+  end
+  let(:context) do
+    Html2rss::Web::RequestContext::Context.new(
+      request_id: 'req-123',
+      path: '/api/v1/feeds/[REDACTED]',
+      http_method: 'GET',
+      route_group: 'api_v1',
+      actor: nil,
+      strategy: 'faraday',
+      started_at: '2026-03-21T00:00:00Z'
+    )
+  end
+
+  before do
+    Html2rss::Web::RequestContext.set!(context)
+    Html2rss::Web::AppLogger.reset_logger!
+    Html2rss::Web::SecurityLogger.reset_logger!
+    allow(Logger).to receive(:new).and_return(test_logger)
+  end
+
+  after do
+    Html2rss::Web::RequestContext.clear!
+  end
+
+  it 'redacts feed tokens from token feed request paths', :aggregate_failures do
+    expect(described_class.sanitize_path('/api/v1/feeds/token-value-123')).to eq('/api/v1/feeds/[REDACTED]')
+    expect(described_class.sanitize_path('/api/v1/feeds/token-value-123.json')).to eq('/api/v1/feeds/[REDACTED].json')
+    expect(
+      described_class.sanitize_path('/api/v1/feeds/eyJwIjoiYS5iLmMifQ==.xml')
+    ).to eq('/api/v1/feeds/[REDACTED].xml')
+  end
+
+  it 'leaves non-feed paths unchanged when they use supported suffixes', :aggregate_failures do
+    expect(described_class.sanitize_path('/api/v1/health.json')).to eq('/api/v1/health.json')
+    expect(described_class.sanitize_path('/api/v1/status.xml')).to eq('/api/v1/status.xml')
+    expect(described_class.sanitize_path('/feeds/public.rss')).to eq('/feeds/public.rss')
+  end
+
+  it 'replaces logged urls with hashed host metadata' do
+    expect(described_class.sanitize_details(url: 'https://news.ycombinator.com')).to eq(url: expected_news_url)
+  end
+
+  it 'falls back to a hash for malformed urls' do
+    expect(described_class.sanitize_details(url: '://bad url')).to eq(
+      url: { hash: Digest::SHA256.hexdigest('://bad url')[0..11] }
+    )
+  end
+
+  it 'sanitizes nested url fields when emitting shared log events' do
+    Html2rss::Web::LogEvent.emit(payload: nested_url_payload)
+
+    payload = JSON.parse(io.string.lines.last, symbolize_names: true)
+
+    expect(payload.slice(:url, :related_urls, :details)).to eq(expected_nested_url_payload)
+  end
+
+  it 'sanitizes security logger token usage fields' do
+    Html2rss::Web::SecurityLogger.log_token_usage('very-secret-token', 'https://news.ycombinator.com', true)
+    payload = JSON.parse(io.string.lines.last, symbolize_names: true)
+
+    expect(payload.slice(:path, :details)).to eq(
+      path: '/api/v1/feeds/[REDACTED]',
+      details: {
+        url: expected_news_url,
+        token_hash: Digest::SHA256.hexdigest('very-secret-token')[0..7],
+        success: true
+      }
+    )
+  end
+
+  it 'sanitizes security logger fallback output when structured logging fails' do
+    allow(Html2rss::Web::LogEvent).to receive(:emit).and_raise(JSON::GeneratorError, 'boom')
+    allow(Kernel).to receive(:warn)
+    emit_failing_token_usage_log
+
+    expect(Kernel).to have_received(:warn).with('Structured logging fallback: JSON::GeneratorError: boom')
+    expect(fallback_warning_line).to eq(expected_fallback_warning_line)
+  end
+
+  it 'sanitizes observability details' do
+    Html2rss::Web::Observability.emit(
+      event_name: 'feed.render',
+      outcome: 'success',
+      details: { url: 'https://news.ycombinator.com', strategy: 'faraday' }
+    )
+
+    lines = io.string.lines.map { |line| JSON.parse(line, symbolize_names: true) }
+    observability_payload = lines.first
+
+    expect(observability_payload.dig(:details, :url)).to eq(expected_news_url)
+  end
+
+  it 'formats rack-timeout logfmt as json' do
+    Html2rss::Web::AppLogger.logger.info('source=rack-timeout id=req-123 timeout=15000ms state=completed')
+
+    payload = JSON.parse(io.string.lines.last, symbolize_names: true)
+    expect(payload).to include(
+      source: 'rack-timeout',
+      id: 'req-123',
+      timeout: '15000ms',
+      state: 'completed'
+    )
+  end
+
+  private
+
+  # @return [Hash{Symbol=>Object}]
+  def nested_url_payload
+    {
+      url: 'https://news.ycombinator.com',
+      related_urls: ['https://example.com/feed.xml'],
+      details: { url: 'https://lobste.rs/s/test' }
+    }
+  end
+
+  # @return [Hash{Symbol=>Object}]
+  def expected_nested_url_payload
+    {
+      url: expected_sanitized_url('news.ycombinator.com', 'https://news.ycombinator.com'),
+      related_urls: [
+        expected_sanitized_url('example.com', 'https://example.com/feed.xml')
+      ],
+      details: {
+        url: expected_sanitized_url('lobste.rs', 'https://lobste.rs/s/test')
+      }
+    }
+  end
+
+  # @param host [String]
+  # @param url [String]
+  # @return [Hash{Symbol=>String}]
+  def expected_sanitized_url(host, url)
+    { host:, scheme: 'https', hash: url_hash(url) }
+  end
+
+  # @param url [String]
+  # @return [String]
+  def url_hash(url)
+    Digest::SHA256.hexdigest(url)[0..11]
+  end
+
+  # @return [void]
+  def emit_failing_token_usage_log
+    Html2rss::Web::SecurityLogger.log_token_usage(
+      'very-secret-token',
+      'https://news.ycombinator.com/private/feed',
+      true
+    )
+  end
+
+  # @return [String]
+  def fallback_warning_line
+    warning_messages = RSpec::Mocks.space.proxy_for(Kernel).messages_arg_list.map(&:first)
+    warning_messages.find { |message| message.include?('component=security_logger') }
+  end
+
+  # @return [Hash{Symbol=>String}]
+  def sanitized_fallback_url
+    expected_sanitized_url('news.ycombinator.com', 'https://news.ycombinator.com/private/feed')
+  end
+
+  # @return [String]
+  def expected_fallback_warning_line
+    'component=security_logger security_event=token_usage ' \
+      "details={success: true, url: #{sanitized_fallback_url.inspect}, token_hash: \"01cadf39\"}"
+  end
+end
diff --git a/spec/html2rss/web/request_context_middleware_spec.rb b/spec/html2rss/web/request_context_middleware_spec.rb
index 6aae8308..0b671407 100644
--- a/spec/html2rss/web/request_context_middleware_spec.rb
+++ b/spec/html2rss/web/request_context_middleware_spec.rb
@@ -4,6 +4,7 @@
 require 'rack/mock'
 
 require_relative '../../../app/web/request/request_context'
+require_relative '../../../app/web/security/log_sanitizer'
 require_relative '../../../app/web/request/request_context_middleware'
 
 RSpec.describe Html2rss::Web::RequestContextMiddleware do
@@ -17,6 +18,11 @@
     expect(response['X-Request-Id']).not_to be_empty
   end
 
+  it 'redacts feed tokens from request context paths' do
+    response = Rack::MockRequest.new(redaction_app).get('/api/v1/feeds/sensitive-token-value.json')
+    expect(response.body).to eq('/api/v1/feeds/[REDACTED].json')
+  end
+
   private
 
   # @return [Html2rss::Web::RequestContextMiddleware]
@@ -27,4 +33,13 @@ def middleware_app
     end
     described_class.new(app)
   end
+
+  # @return [Html2rss::Web::RequestContextMiddleware]
+  def redaction_app
+    app = lambda do |_env|
+      context = Html2rss::Web::RequestContext.current
+      [200, { 'Content-Type' => 'text/plain' }, [context.path]]
+    end
+    described_class.new(app)
+  end
 end