fix(demo): stable DEMO_TAG in embedded mode and portable temp dir

- 00_seed_data.ipynb DEMO_TAG: use a stable "seed_data" tag in embedded
  mode so reseeds cleanly replace prior data via the existing
  DETACH DELETE cleanup. Server mode keeps the UUID-suffixed tag so
  parallel runs sharing a DB remain isolated.
- All 4 notebooks: replace hard-coded "/tmp/coordinode-demo.db" fallback
  with `os.path.join(tempfile.gettempdir(), "coordinode-demo.db")` so the
  default path works on native Windows where /tmp does not exist.

Author: polaz

demo/notebooks/00_seed_data.ipynb

@@ -156,14 +156,16 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import os\n",
+    "import os, tempfile\n",
     "\n",
     "# Persistent embedded DB path. Colab has /content which persists across cell\n",
-    "# reruns within a runtime session; locally fall back to /tmp. Override via\n",
-    "# COORDINODE_EMBEDDED_PATH if you need a different location.\n",
+    "# reruns within a runtime session; locally fall back to the OS temp dir\n",
+    "# (portable across Linux/macOS/Windows). Override via COORDINODE_EMBEDDED_PATH.\n",
     "COORDINODE_EMBEDDED_PATH = os.environ.get(\n",
     "    \"COORDINODE_EMBEDDED_PATH\",\n",
-    "    \"/content/coordinode-demo.db\" if os.path.isdir(\"/content\") else \"/tmp/coordinode-demo.db\",\n",
+    "    \"/content/coordinode-demo.db\"\n",
+    "    if os.path.isdir(\"/content\")\n",
+    "    else os.path.join(tempfile.gettempdir(), \"coordinode-demo.db\"),\n",
     ")\n",
     "\n",
     "if os.environ.get(\"COORDINODE_ADDR\"):\n",
@@ -208,7 +210,15 @@
    "source": [
     "import uuid\n",
     "\n",
-    "DEMO_TAG = os.environ.get(\"COORDINODE_DEMO_TAG\") or f\"seed_data_{uuid.uuid4().hex[:8]}\"\n",
+    "# In server mode (COORDINODE_ADDR) parallel runs may share a DB, so a unique\n",
+    "# UUID tag prevents collisions. In embedded mode each LocalClient has its own\n",
+    "# file-backed DB, so a stable tag lets reseeds cleanly replace prior data\n",
+    "# (the DETACH DELETE below is scoped to this tag).\n",
+    "DEMO_TAG = os.environ.get(\"COORDINODE_DEMO_TAG\") or (\n",
+    "    f\"seed_data_{uuid.uuid4().hex[:8]}\"\n",
+    "    if os.environ.get(\"COORDINODE_ADDR\")\n",
+    "    else \"seed_data\"\n",
+    ")\n",
     "print(\"Using DEMO_TAG:\", DEMO_TAG)\n",
     "# Remove prior demo nodes and any attached relationships in one step to avoid\n",
     "# duplicate relationship matches during cleanup (undirected MATCH -[r]-() returns\n",

demo/notebooks/01_llama_index_property_graph.ipynb

@@ -189,14 +189,16 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import os\n",
+    "import os, tempfile\n",
     "\n",
     "# Persistent embedded DB path. Colab has /content which persists across cell\n",
-    "# reruns within a runtime session; locally fall back to /tmp. Override via\n",
-    "# COORDINODE_EMBEDDED_PATH if you need a different location.\n",
+    "# reruns within a runtime session; locally fall back to the OS temp dir\n",
+    "# (portable across Linux/macOS/Windows). Override via COORDINODE_EMBEDDED_PATH.\n",
     "COORDINODE_EMBEDDED_PATH = os.environ.get(\n",
     "    \"COORDINODE_EMBEDDED_PATH\",\n",
-    "    \"/content/coordinode-demo.db\" if os.path.isdir(\"/content\") else \"/tmp/coordinode-demo.db\",\n",
+    "    \"/content/coordinode-demo.db\"\n",
+    "    if os.path.isdir(\"/content\")\n",
+    "    else os.path.join(tempfile.gettempdir(), \"coordinode-demo.db\"),\n",
     ")\n",
     "\n",
     "if os.environ.get(\"COORDINODE_ADDR\"):\n",

demo/notebooks/02_langchain_graph_chain.ipynb

@@ -190,14 +190,16 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import os\n",
+    "import os, tempfile\n",
     "\n",
     "# Persistent embedded DB path. Colab has /content which persists across cell\n",
-    "# reruns within a runtime session; locally fall back to /tmp. Override via\n",
-    "# COORDINODE_EMBEDDED_PATH if you need a different location.\n",
+    "# reruns within a runtime session; locally fall back to the OS temp dir\n",
+    "# (portable across Linux/macOS/Windows). Override via COORDINODE_EMBEDDED_PATH.\n",
     "COORDINODE_EMBEDDED_PATH = os.environ.get(\n",
     "    \"COORDINODE_EMBEDDED_PATH\",\n",
-    "    \"/content/coordinode-demo.db\" if os.path.isdir(\"/content\") else \"/tmp/coordinode-demo.db\",\n",
+    "    \"/content/coordinode-demo.db\"\n",
+    "    if os.path.isdir(\"/content\")\n",
+    "    else os.path.join(tempfile.gettempdir(), \"coordinode-demo.db\"),\n",
     ")\n",
     "\n",
     "if os.environ.get(\"COORDINODE_ADDR\"):\n",

demo/notebooks/03_langgraph_agent.ipynb

@@ -144,14 +144,16 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import os\n",
+    "import os, tempfile\n",
     "\n",
     "# Persistent embedded DB path. Colab has /content which persists across cell\n",
-    "# reruns within a runtime session; locally fall back to /tmp. Override via\n",
-    "# COORDINODE_EMBEDDED_PATH if you need a different location.\n",
+    "# reruns within a runtime session; locally fall back to the OS temp dir\n",
+    "# (portable across Linux/macOS/Windows). Override via COORDINODE_EMBEDDED_PATH.\n",
     "COORDINODE_EMBEDDED_PATH = os.environ.get(\n",
     "    \"COORDINODE_EMBEDDED_PATH\",\n",
-    "    \"/content/coordinode-demo.db\" if os.path.isdir(\"/content\") else \"/tmp/coordinode-demo.db\",\n",
+    "    \"/content/coordinode-demo.db\"\n",
+    "    if os.path.isdir(\"/content\")\n",
+    "    else os.path.join(tempfile.gettempdir(), \"coordinode-demo.db\"),\n",
     ")\n",
     "\n",
     "if os.environ.get(\"COORDINODE_ADDR\"):\n",