FIX: throwing away first file in diff (#573)

We were chucking out the first file in a PR diff due to a
logic bug

lib/ai_bot/tools/github_pull_request_diff.rb

@@ -63,7 +63,7 @@ module DiscourseAi
 
           if response_code == "200"
             diff = body
-            diff = sort_and_shorten_diff(diff)
+            diff = self.class.sort_and_shorten_diff(diff)
             diff = truncate(diff, max_length: 20_000, percent_length: 0.3, llm: llm)
             { diff: diff }
           else
@@ -75,14 +75,12 @@ module DiscourseAi
           { repo: repo, pull_id: pull_id, url: url }
         end
 
-        private
-
-        def sort_and_shorten_diff(diff, threshold: LARGE_OBJECT_THRESHOLD)
+        def self.sort_and_shorten_diff(diff, threshold: LARGE_OBJECT_THRESHOLD)
           # This regex matches the start of a new file in the diff,
           # capturing the file paths for later use.
           file_start_regex = /^diff --git.*/
 
-          prev_start = 0
+          prev_start = -1
           prev_match = nil
 
           split = []
@@ -90,9 +88,8 @@ module DiscourseAi
           diff.scan(file_start_regex) do |match|
             match_start = $~.offset(0)[0] # Get the start position of this match
 
-            if prev_start != 0
+            if prev_start != -1
               full_diff = diff[prev_start...match_start]
-
               split << [prev_match, full_diff]
             end
 

lib/completions/dialects/llama2_classic.rb

@@ -33,7 +33,7 @@ module DiscourseAi
               elsif msg[:type] == :model
                 memo << "\n#{msg[:content]}"
               elsif msg[:type] == :tool
-                tool = JSON.parse(msg[:content], symbolize_names: true)
+                JSON.parse(msg[:content], symbolize_names: true)
                 memo << "\n[INST]\n"
 
                 memo << (<<~TEXT).strip

spec/lib/completions/dialects/llama2_classic_spec.rb

@@ -12,7 +12,7 @@ RSpec.describe DiscourseAi::Completions::Dialects::Llama2Classic do
       [INST]
       <<SYS>>
       #{context.system_insts}
-      #{described_class.tool_preamble}
+      #{described_class.tool_preamble(include_array_tip: false)}
       <tools>
       #{context.dialect_tools}</tools>
       <</SYS>>
@@ -30,7 +30,7 @@ RSpec.describe DiscourseAi::Completions::Dialects::Llama2Classic do
       [INST]
       <<SYS>>
       #{context.system_insts}
-      #{described_class.tool_preamble}
+      #{described_class.tool_preamble(include_array_tip: false)}
       <tools>
       #{context.dialect_tools}</tools>
       <</SYS>>

spec/lib/completions/dialects/mixtral_spec.rb

@@ -11,7 +11,7 @@ RSpec.describe DiscourseAi::Completions::Dialects::Mixtral do
       llama2_classic_version = <<~TEXT
       <s> [INST]
       #{context.system_insts}
-      #{described_class.tool_preamble}
+      #{described_class.tool_preamble(include_array_tip: false)}
       <tools>
       #{context.dialect_tools}</tools>
       [/INST] Ok </s>
@@ -27,7 +27,7 @@ RSpec.describe DiscourseAi::Completions::Dialects::Mixtral do
       expected = +(<<~TEXT).strip
       <s> [INST]
       #{context.system_insts}
-      #{described_class.tool_preamble}
+      #{described_class.tool_preamble(include_array_tip: false)}
       <tools>
       #{context.dialect_tools}</tools>
       [/INST] Ok </s>

spec/lib/completions/dialects/orca_style_spec.rb

@@ -11,7 +11,7 @@ RSpec.describe DiscourseAi::Completions::Dialects::OrcaStyle do
       llama2_classic_version = <<~TEXT
       ### System:
       #{context.system_insts}
-      #{described_class.tool_preamble}
+      #{described_class.tool_preamble(include_array_tip: false)}
       <tools>
       #{context.dialect_tools}</tools>
       ### User:
@@ -28,7 +28,7 @@ RSpec.describe DiscourseAi::Completions::Dialects::OrcaStyle do
       expected = +(<<~TEXT)
       ### System:
       #{context.system_insts}
-      #{described_class.tool_preamble}
+      #{described_class.tool_preamble(include_array_tip: false)}
       <tools>
       #{context.dialect_tools}</tools>
       ### User:

spec/lib/modules/ai_bot/tools/github_pull_request_diff_spec.rb

@@ -7,6 +7,43 @@ RSpec.describe DiscourseAi::AiBot::Tools::GithubPullRequestDiff do
   let(:bot_user) { Fabricate(:user) }
   let(:llm) { DiscourseAi::Completions::Llm.proxy("open_ai:gpt-4") }
 
+  context "with #sort_and_shorten_diff" do
+    it "sorts and shortens the diff without dropping data" do
+      diff = <<~DIFF
+      diff --git a/src/lib.rs b/src/lib.rs
+      index b466edd..66b068f 100644
+      --- a/src/lib.rs
+      +++ b/src/lib.rs
+      this is a longer diff
+      this is a longer diff
+      this is a longer diff
+      diff --git a/tests/test_encoding.py b/tests/test_encoding.py
+      index 27b2192..9f31319 100644
+      --- a/tests/test_encoding.py
+      +++ b/tests/test_encoding.py
+      short diff
+      DIFF
+
+      sorted_diff = described_class.sort_and_shorten_diff(diff)
+
+      expect(sorted_diff).to eq(<<~DIFF)
+      diff --git a/tests/test_encoding.py b/tests/test_encoding.py
+      index 27b2192..9f31319 100644
+      --- a/tests/test_encoding.py
+      +++ b/tests/test_encoding.py
+      short diff
+
+      diff --git a/src/lib.rs b/src/lib.rs
+      index b466edd..66b068f 100644
+      --- a/src/lib.rs
+      +++ b/src/lib.rs
+      this is a longer diff
+      this is a longer diff
+      this is a longer diff
+      DIFF
+    end
+  end
+
   context "with a valid pull request" do
     let(:repo) { "discourse/discourse-automation" }
     let(:pull_id) { 253 }