feat(scripts): add multiple diff strategies and debug output

Author: rstrahan

scripts/generate_commit_message.sh

@@ -5,42 +5,78 @@
 #   bash scripts/generate_commit_message.sh
 #
 # Environment variables:
-#   COMMIT_MODEL_ID - Bedrock model to use (default: amazon.nova-lite-v1:0)
+#   COMMIT_MODEL_ID - Bedrock model/inference profile to use (default: us.amazon.nova-lite-v1:0)
 #                     Examples:
-#                       amazon.nova-lite-v1:0
-#                       anthropic.claude-3-haiku-20240307-v1:0
+#                       us.amazon.nova-lite-v1:0          (Nova Lite - default, cheapest)
+#                       us.amazon.nova-micro-v1:0         (Nova Micro - fastest)
+#                       us.amazon.nova-pro-v1:0           (Nova Pro - most capable)
+#                       us.anthropic.claude-3-haiku-20240307-v1:0  (Claude Haiku)
 #   AWS_REGION      - AWS region for Bedrock (uses default if not set)
+#   COMMIT_DEBUG    - Set to 1 to enable debug output to stderr
 
 set -euo pipefail
 
-MODEL_ID="${COMMIT_MODEL_ID:-amazon.nova-lite-v1:0}"
+MODEL_ID="${COMMIT_MODEL_ID:-us.amazon.nova-lite-v1:0}"
+DEBUG="${COMMIT_DEBUG:-0}"
 
-# Get the diff - prefer staged changes, fall back to unstaged
-DIFF_STAT=$(git diff --cached --stat 2>/dev/null)
-DIFF_CONTENT=$(git diff --cached 2>/dev/null)
+debug() {
+    if [ "$DEBUG" = "1" ]; then
+        echo "[DEBUG] $*" >&2
+    fi
+}
 
+# Collect diff using multiple strategies (in priority order)
+# After "git add .", staged changes show in "git diff --cached" or "git diff HEAD"
+DIFF_STAT=""
+DIFF_CONTENT=""
+
+# Strategy 1: Staged changes (git diff --cached)
+DIFF_STAT=$(git diff --cached --stat 2>/dev/null || true)
+DIFF_CONTENT=$(git diff --cached 2>/dev/null || true)
+
+# Strategy 2: If no staged changes, try diff against HEAD (catches both staged + unstaged)
+if [ -z "$DIFF_STAT" ]; then
+    debug "No staged diff found, trying HEAD..."
+    DIFF_STAT=$(git diff HEAD --stat 2>/dev/null || true)
+    DIFF_CONTENT=$(git diff HEAD 2>/dev/null || true)
+fi
+
+# Strategy 3: Unstaged changes
 if [ -z "$DIFF_STAT" ]; then
-    DIFF_STAT=$(git diff --stat 2>/dev/null)
-    DIFF_CONTENT=$(git diff 2>/dev/null)
+    debug "No HEAD diff found, trying unstaged..."
+    DIFF_STAT=$(git diff --stat 2>/dev/null || true)
+    DIFF_CONTENT=$(git diff 2>/dev/null || true)
 fi
 
-# If still empty, try diff against HEAD
+# Strategy 4: Last commit diff (if everything is already committed)
 if [ -z "$DIFF_STAT" ]; then
-    DIFF_STAT=$(git diff HEAD --stat 2>/dev/null || echo "no diff available")
-    DIFF_CONTENT=$(git diff HEAD 2>/dev/null || echo "")
+    debug "No working tree diff, using last commit..."
+    DIFF_STAT=$(git diff HEAD~1 --stat 2>/dev/null || echo "no diff available")
+    DIFF_CONTENT=$(git diff HEAD~1 2>/dev/null || echo "")
 fi
 
-# Truncate diff content to ~4000 chars to stay within token limits
-DIFF_TRUNCATED=$(echo "$DIFF_CONTENT" | head -c 4000)
+debug "Diff stat length: ${#DIFF_STAT}"
+debug "Diff content length: ${#DIFF_CONTENT}"
+
+# Truncate diff content to ~6000 chars to stay within token limits while providing good context
+DIFF_TRUNCATED=$(echo "$DIFF_CONTENT" | head -c 6000)
 
 # Build the prompt
-PROMPT="Based on the following git diff, generate a single-line commit message following conventional commit format (e.g., feat:, fix:, docs:, refactor:, chore:, test:).
-Return ONLY the commit message on a single line. No quotes, no explanation, no prefix like 'Commit message:'.
+PROMPT="You are a Git commit message expert. Analyze the following git changes and generate a clear, informative commit message.
+
+Rules:
+1. Use conventional commit format: type(scope): description
+2. Types: feat, fix, docs, refactor, chore, test, style, build, ci, perf
+3. The scope should identify the component or area changed (e.g., makefile, config, api, ui)
+4. The description should concisely summarize WHAT changed and WHY
+5. Return ONLY the commit message on a single line
+6. Do NOT wrap in quotes, do NOT add any explanation or preamble
+7. Keep it under 100 characters
 
 Files changed:
 ${DIFF_STAT}
 
-Diff:
+Diff details:
 ${DIFF_TRUNCATED}"
 
 # Escape the prompt for JSON using jq
@@ -49,23 +85,45 @@ ESCAPED_PROMPT=$(echo "$PROMPT" | jq -Rs .)
 # Build the messages JSON
 MESSAGES="[{\"role\":\"user\",\"content\":[{\"text\":${ESCAPED_PROMPT}}]}]"
 
-# Call Bedrock converse API
-COMMIT_MSG=$(aws bedrock-runtime converse \
+debug "Calling Bedrock with model: $MODEL_ID"
+
+# Call Bedrock converse API - capture both stdout and stderr separately
+BEDROCK_OUTPUT=""
+BEDROCK_ERR=""
+BEDROCK_OUTPUT=$(aws bedrock-runtime converse \
     --model-id "$MODEL_ID" \
     --messages "$MESSAGES" \
     --inference-config '{"maxTokens":100,"temperature":0.3}' \
     --query 'output.message.content[0].text' \
-    --output text 2>&1) || true
+    --output text 2>/tmp/bedrock_commit_err) || true
+
+BEDROCK_ERR=$(cat /tmp/bedrock_commit_err 2>/dev/null || true)
+rm -f /tmp/bedrock_commit_err
 
-# Fallback if Bedrock call fails or returns empty
-if [ -z "$COMMIT_MSG" ] || [ "$COMMIT_MSG" = "None" ] || echo "$COMMIT_MSG" | grep -qi "error"; then
-    # Generate a basic fallback message from the diff stat
-    FILE_COUNT=$(echo "$DIFF_STAT" | grep -c "file" || echo "0")
-    echo "chore: update ${FILE_COUNT} file(s)"
+debug "Bedrock output: '$BEDROCK_OUTPUT'"
+debug "Bedrock stderr: '$BEDROCK_ERR'"
+
+# Check if we got a valid response
+if [ -z "$BEDROCK_OUTPUT" ] || [ "$BEDROCK_OUTPUT" = "None" ] || [ "$BEDROCK_OUTPUT" = "null" ]; then
+    debug "Bedrock returned empty/None, using fallback"
+    if [ -n "$BEDROCK_ERR" ]; then
+        debug "Bedrock error: $BEDROCK_ERR"
+    fi
+    # Generate a descriptive fallback from the diff stat
+    SUMMARY=$(echo "$DIFF_STAT" | head -5 | tr '\n' ', ' | sed 's/, $//')
+    echo "chore: update files - ${SUMMARY}"
     exit 0
 fi
 
-# Clean up - remove surrounding quotes if present, trim whitespace
-COMMIT_MSG=$(echo "$COMMIT_MSG" | sed 's/^["'"'"']//;s/["'"'"']$//' | xargs)
+# Clean up - strip code blocks, remove surrounding quotes, trim whitespace
+# Models sometimes wrap output in ```bash ... ``` or ```...```
+COMMIT_MSG=$(echo "$BEDROCK_OUTPUT" | \
+    sed '/^```/d' | \
+    sed 's/^["'"'"']*//;s/["'"'"']*$//' | \
+    grep -v '^[[:space:]]*$' | \
+    head -1 | \
+    xargs)
+
+debug "Final commit message: '$COMMIT_MSG'"
 
 echo "$COMMIT_MSG"