diff --git a/app/controllers/api/hackatime/v1/hackatime_controller.rb b/app/controllers/api/hackatime/v1/hackatime_controller.rb
index 50eef0e..1ca1c30 100644
--- a/app/controllers/api/hackatime/v1/hackatime_controller.rb
+++ b/app/controllers/api/hackatime/v1/hackatime_controller.rb
@@ -234,6 +234,10 @@ class Api::Hackatime::V1::HackatimeController < ApplicationController
     heartbeat_array.each do |heartbeat|
       source_type = :direct_entry
 
+      # Fallback to :plugin if :user_agent is not set
+      fallback_value = heartbeat.delete(:plugin)
+      heartbeat[:user_agent] ||= fallback_value
+
       parsed_ua = WakatimeService.parse_user_agent(heartbeat[:user_agent])
 
       # special case: if the entity is "test.txt", this is a test heartbeat
@@ -318,7 +322,8 @@ class Api::Hackatime::V1::HackatimeController < ApplicationController
       :project_root_count,
       :time,
       :type,
-      :user_agent
+      :user_agent,
+      :plugin
     ]
   end
 
@@ -328,8 +333,9 @@ class Api::Hackatime::V1::HackatimeController < ApplicationController
       { heartbeats: params.permit(_json: [ *heartbeat_keys ])[:_json] }
     elsif request.content_type&.include?("text/plain") && request.raw_post.present?
       # Handle text/plain requests by parsing JSON directly
-      parsed_json = JSON.parse(request.raw_post) rescue []
-      { heartbeats: parsed_json }
+      parsed_json = JSON.parse(request.raw_post, symbolize_names: true) rescue []
+      filtered_json = parsed_json.map { |hb| hb.slice(*heartbeat_keys) }
+      { heartbeats: filtered_json }
     else
       params.require(:hackatime).permit(
         heartbeats: [
@@ -345,7 +351,7 @@ class Api::Hackatime::V1::HackatimeController < ApplicationController
       params[:_json].first.permit(*heartbeat_keys)
     elsif request.content_type&.include?("text/plain") && request.raw_post.present?
       # Handle text/plain requests by parsing JSON directly
-      parsed_json = JSON.parse(request.raw_post) rescue {}
+      parsed_json = JSON.parse(request.raw_post, symbolize_names: true) rescue {}
       parsed_json = [ parsed_json ] unless parsed_json.is_a?(Array)
       parsed_json.first&.with_indifferent_access&.slice(*heartbeat_keys) || {}
     elsif params[:hackatime].present?
diff --git a/lib/wakatime_service.rb b/lib/wakatime_service.rb
index bc69b69..1d49062 100644
--- a/lib/wakatime_service.rb
+++ b/lib/wakatime_service.rb
@@ -87,7 +87,18 @@ class WakatimeService
     else
       # Try parsing as browser user agent as fallback
       if browser_ua = user_agent.match(/^([^\/]+)\/([^\/\s]+)/)
-        { os: browser_ua[1], editor: browser_ua[2], err: nil }
+        # If "wakatime" is present, assume it's the browser extension
+        if user_agent.include?("wakatime") then
+            full_os = user_agent.split(" ")[1]
+            if full_os.present?
+              os = full_os.include?("_") ? full_os.split("_")[0] : full_os
+              { os: os, editor: browser_ua[1].downcase, err: nil }
+            else
+              { os: "", editor: "", err: "failed to parse user agent string" }
+            end
+        else
+          { os: browser_ua[1], editor: browser_ua[2], err: nil }
+        end
       else
         { os: "", editor: "", err: "failed to parse user agent string" }
       end
diff --git a/test/lib/wakatime_service_test.rb b/test/lib/wakatime_service_test.rb
index e46b074..cb5d07e 100644
--- a/test/lib/wakatime_service_test.rb
+++ b/test/lib/wakatime_service_test.rb
@@ -63,6 +63,14 @@ class WakatimeServiceTest < Minitest::Test
     assert_nil result[:error]
   end
 
+  def test_parse_user_agent_with_Firefox
+    user_agent = "Firefox/139.0 linux_x86-64 firefox-wakatime/4.1.0"
+    result = WakatimeService.parse_user_agent(user_agent)
+    assert_equal "linux", result[:os]
+    assert_equal "firefox", result[:editor]
+    assert_nil result[:error]
+  end
+
   def test_parse_user_agent_with_invalid_user_agent
     user_agent = "invalid-user-agent"
     result = WakatimeService.parse_user_agent(user_agent)