feat: add configurable line limit and split logic for changelog updates

bin/update-changelog-with-llm

@@ -1,6 +1,8 @@
 #!/usr/bin/env bash
 
 update-changelog-with-llm() {
+    local num_lines="${1:-100}"
+
     # Check if CHANGELOG.md exists
     if [[ ! -f "CHANGELOG.md" ]]; then
         echo "Error: CHANGELOG.md not found in the current directory."
@@ -16,23 +18,31 @@ update-changelog-with-llm() {
     # Create tmp directory if it doesn't exist
     mkdir -p tmp
 
+    # Split CHANGELOG.md into the portion we'll send to the LLM and the rest
+    local top_file="tmp/changelog_top"
+    local rest_file="tmp/changelog_rest"
+    head -n "$num_lines" CHANGELOG.md > "$top_file"
+    tail -n +"$((num_lines + 1))" CHANGELOG.md > "$rest_file"
+
     # Create prompt file
-    local prompt_file="tmp/llm_changelog_update"
+    local prompt_file="tmp/llm_prompt"
     echo -e "\nWrite prompt to $prompt_file."
     cat << EOF > "$prompt_file"
-Update a CHANGELOG.md file based on the git diff provided.
+Update the top portion of a CHANGELOG.md file based on the git diff provided.
+
+Below is only the first $num_lines line(s) of CHANGELOG.md, not the whole file. The remainder of the file is not shown and must not be referenced or reproduced.
 
 Follow these instructions:
-1. Read the existing CHANGELOG.md content below
+1. Read the provided CHANGELOG.md excerpt below
 2. Analyze the git diff to understand what changes were made
-3. Update the CHANGELOG.md to include these changes in the appropriate section
-4. Follow the Keep a Changelog format (https://keepachangelog.com/en/1.1.0/)
-6. Maintain the existing format and structure of the CHANGELOG.md
+3. Update the excerpt to include these changes in the appropriate section (e.g. add an "Unreleased" entry, or a new version section, following Keep a Changelog format: https://keepachangelog.com/en/1.1.0/)
+4. Maintain the existing formatting and structure of the excerpt
+5. Do not truncate or omit any part of the excerpt that doesn't need to change
 
-Reply with the complete updated CHANGELOG.md content only, in the exact same format as provided.
+Reply with the complete updated excerpt only, in the exact same format as provided, and nothing else (no preamble, no explanation, no code fences).
 
-<<<CHANGELOG.md>>>
-$(cat CHANGELOG.md )
+<<<CHANGELOG.md (top $num_lines lines)>>>
+$(cat "$top_file")
 
 <<<git diff --staged>>>
 $(git diff --staged)
@@ -40,7 +50,7 @@ $(git diff --staged)
 EOF
 
     # Run the llm command
-    echo -e "Send prompt with CHANGELOG.md and git diff to LLM and wait for response."
+    echo -e "Send prompt with CHANGELOG.md excerpt and git diff to LLM and wait for response."
     local result=$(cat "$prompt_file" | llm)
 
     # Check if result is empty
@@ -50,7 +60,7 @@ EOF
     fi
 
     # Save the result to a file
-    local result_file="tmp/llm_changelog_result"
+    local result_file="tmp/llm_prompt_result"
     echo "$result" > "$result_file"
     echo -e "Saved response to $result_file.\n"
 
@@ -63,8 +73,9 @@ EOF
         exit 0
     fi
 
-    # Update CHANGELOG.md
-    cp "$result_file" CHANGELOG.md
+    # Update CHANGELOG.md: new top + untouched rest
+    cat "$result_file" "$rest_file" > tmp/changelog_new
+    cp tmp/changelog_new CHANGELOG.md
     echo "CHANGELOG.md has been updated."
 
     # Stage the updated CHANGELOG.md
@@ -77,4 +88,4 @@ EOF
 }
 ucwl() {
     update-changelog-with-llm "$@"
-}
+}