diff --git a/lib/cloud_controller/runners/puma_runner.rb b/lib/cloud_controller/runners/puma_runner.rb
index 1211a1457d..f1d378dafb 100644
--- a/lib/cloud_controller/runners/puma_runner.rb
+++ b/lib/cloud_controller/runners/puma_runner.rb
@@ -1,7 +1,7 @@
 require 'puma'
 require 'puma/configuration'
 require 'puma/events'
-require 'cloud_controller/logs/steno_io'
+require 'steno/steno'
 require 'cloud_controller/execution_context'
 
 module VCAP::CloudController
@@ -51,7 +51,7 @@ def initialize(config, app, logger, periodic_updater, request_logs)
         conf.before_worker_shutdown { request_logs.log_incomplete_requests if request_logs }
       end
 
-      log_writer = Puma::LogWriter.new(StenoIO.new(logger, :info), StenoIO.new(logger, :error))
+      log_writer = Puma::LogWriter.new(Steno::LoggerIO.new(logger, :info), Steno::LoggerIO.new(logger, :error))
 
       events = Puma::Events.new
       events.after_booted { @periodic_updater.setup_updates }
diff --git a/lib/steno/README.md b/lib/steno/README.md
index b69bd4529c..1a408ec75e 100644
--- a/lib/steno/README.md
+++ b/lib/steno/README.md
@@ -23,7 +23,7 @@ This is a **modified version** of the original Steno library, adapted for CCNG's
 - Custom RFC3339 codec (previously in `lib/steno_custom_codec_temp/`)
 - LICENSE file (Apache 2.0 - for attribution)
 - NOTICE file (Apache 2.0 copyright notices)
-- Test suite (in `spec/unit/lib/steno/`)
+- Test suite (in `spec/isolated_specs/steno/`)
 
 ## What Was Excluded
 
@@ -66,7 +66,7 @@ Syslog.close if Syslog.opened?
   - Required adding `require 'active_support/core_ext/module/delegation'`
 
 ### 4. Test Structure Updates
-- Moved tests from `lib/steno/spec/` to `spec/unit/lib/steno/` (CCNG convention)
+- Moved tests from `lib/steno/spec/` to `spec/isolated_specs/steno/` (CCNG convention)
 - Removed global spec_helper requires, added explicit requires per test
 - Wrapped test describes in parent `RSpec.describe` blocks
 
@@ -75,7 +75,7 @@ Syslog.close if Syslog.opened?
 
 **Removed**:
 - `lib/steno/sink/eventlog.rb` (Windows Event Log sink)
-- `spec/unit/lib/steno/unit/sink/eventlog_spec.rb`
+- `spec/isolated_specs/steno/unit/sink/eventlog_spec.rb`
 - Windows conditionals from config.rb, syslog.rb, test files
 - `WINDOWS` constant from sink/base.rb
 
@@ -86,8 +86,8 @@ Syslog.close if Syslog.opened?
 - `lib/steno/version.rb` - Version constant no longer needed (not a gem)
 - `lib/steno/json_prettifier.rb` - CLI tool for prettifying logs, unused (~110 lines)
 - `lib/steno/core_ext.rb` - Monkey patches for `.logger` on Module/Class/Object, CCNG uses `Steno.logger()` instead (~50 lines)
-- `spec/unit/lib/steno/unit/json_prettifier_spec.rb` - Tests for removed feature
-- `spec/unit/lib/steno/unit/core_ext_spec.rb` - Tests for removed feature
+- `spec/isolated_specs/steno/unit/json_prettifier_spec.rb` - Tests for removed feature
+- `spec/isolated_specs/steno/unit/core_ext_spec.rb` - Tests for removed feature
 - Removed `require 'steno/version'` from steno.rb
 
 **What's kept** (even if unused):
@@ -120,6 +120,16 @@ Syslog.close if Syslog.opened?
 - `Steno::Context::Null` - Default fallback context
 - All log levels including debug1, debug2 - debug2 is actively used
 
+### 8. LoggerIO Adapter for Puma Integration
+**Rationale**: `Puma::LogWriter` requires IO-compatible objects. Previously, a `StenoIO` class existed outside the Steno library to bridge this gap. Since Steno is now inlined, the adapter was moved into the Steno namespace for consistency.
+
+**Added**:
+- `lib/steno/logger_io.rb`: `Steno::LoggerIO` - an IO adapter that wraps a `Steno::Logger` and forwards `write`/`puts` calls to it at a configured log level. Used by `PumaRunner` to pass Steno loggers as IO objects to `Puma::LogWriter`.
+- `spec/isolated_specs/steno/unit/logger_io_spec.rb`: Tests for `Steno::LoggerIO`.
+
+**Modified**:
+- `lib/steno/logger.rb`: Broadened the callstack filter from removing only frames from `logger.rb` to removing all frames within `lib/steno/`. This ensures that log records originating via `Steno::LoggerIO` correctly attribute the source location to the caller rather than to the adapter itself.
+
 ---
 
 ## Making Future Modifications
@@ -129,7 +139,7 @@ If you modify this integrated steno library:
 1. **Document changes** in the "Modifications Made After Integration" section above
 2. **Include rationale** for why the change was made
 3. **List affected files** and what changed
-4. **Run tests** to ensure nothing breaks: `bundle exec rspec spec/unit/lib/steno/`
+4. **Run tests** to ensure nothing breaks: `bundle exec rspec spec/isolated_specs/steno/`
 5. **Update this README** in the same commit as your changes
 
 ## Original Steno Commit History (102 commits)
diff --git a/lib/steno/logger.rb b/lib/steno/logger.rb
index 0827618d19..10db7983c2 100644
--- a/lib/steno/logger.rb
+++ b/lib/steno/logger.rb
@@ -128,21 +128,11 @@ def log(level_name, message=nil, user_data=nil)
   private
 
   def parse_record_loc(callstack)
-    file = nil
-    lineno = nil
-    method = nil
+    frame = callstack.find { |f| f !~ %r{/lib/steno/} } || callstack.last
 
-    callstack.each do |frame|
-      next if frame =~ /logger\.rb/
-
-      file, lineno, method = frame.split(':')
-
-      lineno = lineno.to_i
-
-      method = ::Regexp.last_match(1) if method =~ /in `([^']+)/
-
-      break
-    end
+    file, lineno, method = frame.split(':')
+    lineno = lineno.to_i
+    method = ::Regexp.last_match(1) if method =~ /in `([^`']+)/
 
     [file, lineno, method]
   end
diff --git a/lib/cloud_controller/logs/steno_io.rb b/lib/steno/logger_io.rb
similarity index 88%
rename from lib/cloud_controller/logs/steno_io.rb
rename to lib/steno/logger_io.rb
index a72359ea6d..3e1993718e 100644
--- a/lib/cloud_controller/logs/steno_io.rb
+++ b/lib/steno/logger_io.rb
@@ -1,4 +1,7 @@
-class StenoIO
+module Steno
+end
+
+class Steno::LoggerIO
   def initialize(logger, level)
     @logger = logger
     @level = level
diff --git a/lib/steno/steno.rb b/lib/steno/steno.rb
index 955cf9ef36..7ebabbc27e 100644
--- a/lib/steno/steno.rb
+++ b/lib/steno/steno.rb
@@ -3,6 +3,7 @@
 require 'steno/context'
 require 'steno/errors'
 require 'steno/log_level'
+require 'steno/logger_io'
 require 'steno/logger'
 require 'steno/record'
 require 'steno/sink'
diff --git a/spec/isolated_specs/steno/unit/logger_io_spec.rb b/spec/isolated_specs/steno/unit/logger_io_spec.rb
new file mode 100644
index 0000000000..a0ca39e141
--- /dev/null
+++ b/spec/isolated_specs/steno/unit/logger_io_spec.rb
@@ -0,0 +1,34 @@
+require 'steno/steno'
+
+RSpec.describe Steno::LoggerIO do
+  let(:logger) { double(:logger) }
+  let(:level) { :info }
+  let(:logger_io) { described_class.new(logger, level) }
+
+  describe '#write' do
+    it 'writes to the logger' do
+      expect(logger).to receive(:log).with(level, 'message')
+
+      logger_io.write('message')
+    end
+  end
+
+  describe '#sync' do
+    it 'returns true' do
+      expect(logger_io.sync).to be(true)
+    end
+  end
+
+  context 'when writing a record' do
+    let(:logger) { Steno::Logger.new('test', []) }
+
+    it 'removes logger_io.rb from the callstack' do
+      expect(Steno::Record).to receive(:new).and_wrap_original do |original_method, source, log_level, message, loc, data|
+        expect(loc[0]).not_to match(/logger_io\.rb/)
+        original_method.call(source, log_level, message, loc, data)
+      end
+
+      logger_io.write('message')
+    end
+  end
+end
diff --git a/spec/isolated_specs/steno/unit/logger_spec.rb b/spec/isolated_specs/steno/unit/logger_spec.rb
index c805db813d..d30e9b3947 100644
--- a/spec/isolated_specs/steno/unit/logger_spec.rb
+++ b/spec/isolated_specs/steno/unit/logger_spec.rb
@@ -74,13 +74,18 @@
     end
 
     it 'creates a record with the proper level' do
-      sink = double('sink')
       expect(Steno::Record).to receive(:new).with('test', :warn, 'message', anything, anything).and_call_original
-      allow(sink).to receive(:add_record)
 
-      my_logger = described_class.new('test', [sink])
+      logger.warn('message')
+    end
+
+    it 'creates a record with logger.rb being removed from the callstack' do
+      expect(Steno::Record).to receive(:new).and_wrap_original do |original_method, source, log_level, message, loc, data|
+        expect(loc[0]).not_to match(/logger\.rb/)
+        original_method.call(source, log_level, message, loc, data)
+      end
 
-      my_logger.warn('message')
+      logger.warn('message')
     end
   end
 
diff --git a/spec/unit/lib/cloud_controller/logs/steno_io_spec.rb b/spec/unit/lib/cloud_controller/logs/steno_io_spec.rb
deleted file mode 100644
index 3b871ccf8b..0000000000
--- a/spec/unit/lib/cloud_controller/logs/steno_io_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require 'spec_helper'
-
-module VCAP::CloudController::Logs
-  RSpec.describe StenoIO do
-    let(:logger) { double(:logger) }
-    let(:level) { :info }
-
-    subject { StenoIO.new(logger, level) }
-
-    describe '#write' do
-      it 'writes to the logger' do
-        expect(logger).to receive(:log).with(level, 'message')
-
-        subject.write('message')
-      end
-    end
-
-    describe '#sync' do
-      it 'returns true' do
-        expect(subject.sync).to be(true)
-      end
-    end
-  end
-end