DEV: Prefer ENV key for seeded models (#893)

This PR ensures we prefer getting the API key from environment variables when it is a seeded model.

app/models/llm_model.rb

@@ -95,7 +95,16 @@ class LlmModel < ActiveRecord::Base
   end
 
   def seeded?
-    id < 0
+    id.present? && id < 0
+  end
+
+  def api_key
+    if seeded?
+      env_key = "DISCOURSE_AI_SEEDED_LLM_API_KEY_#{id.abs}"
+      ENV[env_key] || self[:api_key]
+    else
+      self[:api_key]
+    end
   end
 
   private

spec/models/llm_model_spec.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+RSpec.describe LlmModel do
+  describe "api_key" do
+    fab!(:llm_model) { Fabricate(:seeded_model) }
+
+    before { ENV["DISCOURSE_AI_SEEDED_LLM_API_KEY_2"] = "blabla" }
+
+    it "should use environment variable over database value if seeded LLM" do
+      expect(llm_model.api_key).to eq("blabla")
+    end
+  end
+end