fix: make SessionStart hook robust — no set -e, graceful fallbacks

hooks/session-start

@@ -2,9 +2,11 @@
 # SessionStart hook for ArcheFlow plugin.
 # Injects the using-archeflow skill as additional context.
 
-set -euo pipefail
+PLUGIN_ROOT="$(cd "$(dirname "$0")/.." 2>/dev/null && pwd)" || {
+  echo '{}'
+  exit 0
+}
 
-PLUGIN_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
 SKILL_FILE="${PLUGIN_ROOT}/skills/using-archeflow/SKILL.md"
 
 if [ ! -f "$SKILL_FILE" ]; then
@@ -12,18 +14,28 @@ if [ ! -f "$SKILL_FILE" ]; then
   exit 0
 fi
 
-CONTENT=$(awk 'BEGIN{skip=0} /^---$/{skip++; next} skip>=2{print}' "$SKILL_FILE")
+# Strip YAML frontmatter (everything between first two --- lines)
+CONTENT=$(awk 'BEGIN{skip=0} /^---$/{skip++; next} skip>=2{print}' "$SKILL_FILE" 2>/dev/null) || {
+  echo '{}'
+  exit 0
+}
 
-# Use node if available, fall back to printf-based JSON escaping
+if [ -z "$CONTENT" ]; then
+  echo '{}'
+  exit 0
+fi
+
+# JSON-escape and output
 if command -v node &>/dev/null; then
-  node -e "
-    const content = require('fs').readFileSync('/dev/stdin', 'utf8');
-    console.log(JSON.stringify({
-      hookSpecificOutput: { additionalContext: content }
-    }));
-  " <<< "$CONTENT"
+  node -e '
+    const content = require("fs").readFileSync(0, "utf8");
+    console.log(JSON.stringify({ hookSpecificOutput: { additionalContext: content } }));
+  ' <<< "$CONTENT"
 else
-  # Portable fallback: escape for JSON using sed
-  ESCAPED=$(printf '%s' "$CONTENT" | sed -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e ':a;N;$!ba;s/\n/\\n/g')
+  # Portable fallback
+  ESCAPED=$(printf '%s' "$CONTENT" | sed -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e ':a;N;$!ba;s/\n/\\n/g' 2>/dev/null) || {
+    echo '{}'
+    exit 0
+  }
   printf '{"hookSpecificOutput":{"additionalContext":"%s"}}' "$ESCAPED"
 fi