fix(output): separate the stdout and stderr logs

This introduces a new output that holds only the error logs. Previously, the single error stream was being clobbered by both stderr and stdout writing to the same file. Also, you probably want the output values to be different.

Author: sethvargo

action.yml

@@ -60,6 +60,9 @@ outputs:
   summary:
     description: 'The summarized output from the Gemini CLI execution.'
     value: '${{ steps.gemini_run.outputs.gemini_response }}'
+  error:
+    description: 'The error output from the Gemini CLI execution, if any.'
+    value: '${{ steps.gemini_run.outputs.gemini_errors }}'
 
 runs:
   using: 'composite'
@@ -149,22 +152,20 @@ runs:
 
         # Create a temporary directory for storing the output, and ensure it's
         # cleaned up later
-        TEMP_OUTPUT="$(mktemp -p "${RUNNER_TEMP}" gemini.XXXXXXXXXX)"
+        TEMP_STDOUT="$(mktemp -p "${RUNNER_TEMP}" gemini-out.XXXXXXXXXX)"
+        TEMP_STDERR="$(mktemp -p "${RUNNER_TEMP}" gemini-err.XXXXXXXXXX)"
         function cleanup {
-          rm -f "${TEMP_OUTPUT}"
+          rm -f "${TEMP_STDOUT}" "${TEMP_STDERR}"
         }
         trap cleanup EXIT
 
         # Run Gemini CLI with the provided prompt
-        if ! gemini --yolo --prompt "${PROMPT}" &> "${TEMP_OUTPUT}"; then
-          GEMINI_RESPONSE="$(cat "${TEMP_OUTPUT}")"
-          FIRST_LINE="$(echo "${GEMINI_RESPONSE}" | head -n1)"
-          echo "::error title=Gemini CLI execution failed::${FIRST_LINE}"
-          echo "${GEMINI_RESPONSE}"
-          exit 1
+        FAILED=false
+        if ! gemini --yolo --prompt "${PROMPT}" 2> "${TEMP_STDERR}" 1> "${TEMP_STDOUT}"; then
+          FAILED=true
         fi
 
-        GEMINI_RESPONSE="$(cat "${TEMP_OUTPUT}")"
+        GEMINI_RESPONSE="$(cat "${TEMP_STDOUT}")"
 
         # Print the response
         echo "::group::Gemini response"
@@ -175,6 +176,25 @@ runs:
         echo "gemini_response<<EOF" >> "${GITHUB_OUTPUT}"
         echo "${GEMINI_RESPONSE}" >> "${GITHUB_OUTPUT}"
         echo "EOF" >> "${GITHUB_OUTPUT}"
+
+        GEMINI_ERRORS="$(cat "${TEMP_STDERR}")"
+
+        # Print any errors
+        echo "::group::Gemini error messages"
+        echo "${GEMINI_ERRORS}"
+        echo "::endgroup::"
+
+        # Set the captured errors as a step output, supporting multiline
+        echo "gemini_errors<<EOF" >> "${GITHUB_OUTPUT}"
+        echo "${GEMINI_ERRORS}" >> "${GITHUB_OUTPUT}"
+        echo "EOF" >> "${GITHUB_OUTPUT}"
+
+        if [[ "${FAILED}" = true ]]; then
+          LAST_LINE="$(echo "${GEMINI_ERRORS}" | tail -n1)"
+          echo "::error title=Gemini CLI execution failed::${LAST_LINE}"
+          echo "See logs for more details"
+          exit 1
+        fi
       env:
         GEMINI_API_KEY: '${{ inputs.gemini_api_key }}'
         SURFACE: 'GitHub'