fix: add JSON validation in write_index to prevent malformed index.json

The index.json was getting corrupted (ending with 'issues: }' instead of 'issues: {}').
Added validation that checks if the JSON is valid before moving the temp file.
If invalid, the write is aborted with an error message showing the problematic values.

skills/kugetsu/scripts/kugetsu

@@ -481,6 +481,13 @@ write_index() {
     local issues_json="$3"
     local temp_file="$INDEX_FILE.tmp.$$"
     printf '{"base": %s, "pm_agent": %s, "issues": %s}\n' "$base" "$pm_agent" "$issues_json" > "$temp_file"
+    
+    if ! python3 -c "import json; json.load(open('$temp_file'))" 2>/dev/null; then
+        echo "Error: write_index would create malformed JSON, aborting. base=$base, pm_agent=$pm_agent, issues_json=$issues_json" >&2
+        rm -f "$temp_file"
+        return 1
+    fi
+    
     mv "$temp_file" "$INDEX_FILE"
 }
 

skills/kugetsu/scripts/kugetsu-index.sh

@@ -15,6 +15,13 @@ write_index() {
     local issues_json="$3"
     local temp_file="$INDEX_FILE.tmp.$$"
     printf '{"base": %s, "pm_agent": %s, "issues": %s}\n' "$base" "$pm_agent" "$issues_json" > "$temp_file"
+    
+    if ! python3 -c "import json; json.load(open('$temp_file'))" 2>/dev/null; then
+        echo "Error: write_index would create malformed JSON, aborting. base=$base, pm_agent=$pm_agent, issues_json=$issues_json" >&2
+        rm -f "$temp_file"
+        return 1
+    fi
+    
     mv "$temp_file" "$INDEX_FILE"
 }