fix(mem0-plugin): graceful degradation without API key, stdin support

- SessionStart shows "Mem0 Inactive" banner with identity info when no
  API key set, instead of silently exiting with zero output
- on_user_prompt.sh fires error/file-path detection even without API key
  (local pattern matching, no API needed). Search rubric still gated.
- parse_export_file.py supports '-' argument for stdin piping

mem0-plugin/scripts/on_session_start.sh

@@ -19,18 +19,22 @@ SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 # shellcheck source=_identity.sh
 . "$SCRIPT_DIR/_identity.sh"
 
-# Skip the bootstrap entirely if no API key is configured -- the agent
-# would otherwise be told to call mem0 MCP tools that will all fail.
-if [ -z "${MEM0_API_KEY:-}" ]; then
-  exit 0
-fi
-
 # Initialize session stats tracker
 python3 "$SCRIPT_DIR/session_stats.py" init 2>/dev/null || true
 
 INPUT=$(cat)
 SOURCE=$(echo "$INPUT" | jq -r '.source // "startup"' 2>/dev/null || echo "startup")
 
+# Skip bootstrap if no API key — still show banner but with "no key" status.
+if [ -z "${MEM0_API_KEY:-}" ]; then
+  echo "## Mem0 Inactive"
+  echo ""
+  echo "\`user=${MEM0_RESOLVED_USER_ID:-$USER} | project=${MEM0_PROJECT_ID:-unknown} | branch=${MEM0_BRANCH:-unknown} | api_key=NOT_SET\`"
+  echo ""
+  echo "Set MEM0_API_KEY to enable persistent memory. Get a key at https://app.mem0.ai/dashboard/api-keys"
+  exit 0
+fi
+
 # Fetch project-scoped memory count (best-effort, don't block on failure, 5s timeout)
 MEM0_COUNT="?"
 if command -v python3 >/dev/null 2>&1; then

mem0-plugin/scripts/on_user_prompt.sh

@@ -29,21 +29,27 @@ SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 # shellcheck source=_identity.sh
 . "$SCRIPT_DIR/_identity.sh"
 
-# No API key means the agent can't search anyway
-if [ -z "${MEM0_API_KEY:-}" ]; then
-  exit 0
-fi
-USER_ID="$MEM0_RESOLVED_USER_ID"
-
-# Detect stack traces and error patterns in the prompt
+# Detect stack traces and error patterns in the prompt (no API needed)
 HAS_ERROR=""
 if echo "$PROMPT" | grep -qiE '(Traceback|Error:|Exception:|panic:|FAILED|fatal:| at .+\.[a-z]+:[0-9]+)'; then
   HAS_ERROR="true"
 fi
 
-# Detect file paths in the prompt
+# Detect file paths in the prompt (no API needed)
 FILE_PATHS=$(echo "$PROMPT" | grep -oE '([a-zA-Z0-9_./-]+\.(py|ts|tsx|js|jsx|rs|go|rb|java|sh|yaml|yml|json|toml|md|sql|css|html))\b' 2>/dev/null | head -5 || echo "")
 
+# No API key — emit detections only, skip search rubric
+if [ -z "${MEM0_API_KEY:-}" ]; then
+  if [ -n "$HAS_ERROR" ]; then
+    echo "**ERROR DETECTED in prompt.** Set MEM0_API_KEY to search past debugging context."
+  fi
+  if [ -n "$FILE_PATHS" ]; then
+    echo "**FILE PATHS detected:** \`$FILE_PATHS\`"
+  fi
+  exit 0
+fi
+USER_ID="$MEM0_RESOLVED_USER_ID"
+
 cat <<EOF
 ## Memory check
 

mem0-plugin/scripts/parse_export_file.py

@@ -131,8 +131,11 @@ def main() -> None:
 
     filepath = sys.argv[1]
     try:
-        with open(filepath, encoding="utf-8", errors="replace") as f:
-            content = f.read()
+        if filepath == "-":
+            content = sys.stdin.read()
+        else:
+            with open(filepath, encoding="utf-8", errors="replace") as f:
+                content = f.read()
     except OSError as e:
         print(f"Error reading file: {e}", file=sys.stderr)
         print("[]")