diff --git a/database/operations.py b/database/operations.py
index aaaf2bd3..65dc2552 100644
--- a/database/operations.py
+++ b/database/operations.py
@@ -46,6 +46,7 @@ try:
     from ..utils.logging_config import get_logger
     from ..utils.hashing import generate_prompt_hash
     from ..utils.json_strict import dumps_strict
+    from ..utils import library_location
 except ImportError:
     import sys
 
@@ -54,6 +55,7 @@ except ImportError:
     from utils.logging_config import get_logger
     from utils.hashing import generate_prompt_hash
     from utils.json_strict import dumps_strict
+    from utils import library_location
 
 
 # Subquery to fetch tags from junction table, embedded in SELECT statements
@@ -99,40 +101,67 @@ def escape_like(term: str) -> str:
     )
 
 
-def _resolve_db_path(db_path: Optional[str] = None) -> str:
-    """Resolve the database path from config, falling back to defaults.
+def _configured_library():
+    """``(database.default_path, gallery roots)`` from config, or ``(None, [])``.
 
-    When no explicit path is given, reads PromptManagerConfig.DEFAULT_DB_PATH
-    (set via config.json). Relative paths are resolved against the extension
-    root directory so the database location is predictable regardless of the
-    process working directory (important for Docker deployments).
+    The package-qualified config wins over a standalone ``py.config`` (a
+    custom-node package uses its own configuration).
+    """
+    try:
+        try:
+            from ..py.config import PromptManagerConfig
+        except ImportError:
+            from py.config import PromptManagerConfig
+    except Exception:
+        return None, []
+    roots = []
+    try:
+        try:
+            from ..py.config import GalleryConfig
+        except ImportError:
+            from py.config import GalleryConfig
+        directories = list(GalleryConfig.MONITORING_DIRECTORIES or [])
+    except Exception:
+        directories = []
+    for directory in directories:
+        try:
+            roots.append(GalleryConfig.resolve_gallery_root(directory))
+        except Exception:
+            continue
+    return getattr(PromptManagerConfig, "DEFAULT_DB_PATH", None), roots
+
+
+def resolve_library_location():
+    """Where the library lives now (``utils.library_location``, #249 S6b)."""
+    default_path, roots = _configured_library()
+    return library_location.resolve_library(default_path, gallery_roots=roots)
+
+
+def _resolve_db_path(db_path: Optional[str] = None) -> str:
+    """Resolve the database path through the one library resolver.
+
+    With no explicit path, ``utils.library_location.resolve_library`` decides
+    (``PROMPT_MANAGER_DATA_DIR``, an explicit ``database.default_path``, a
+    node-folder library not moved yet, else ComfyUI's ``user/__promptmanager``).
+    An explicit relative path is resolved against the extension root, as
+    before, so the location does not depend on the working directory.
 
     Args:
-        db_path: Explicit database path, or None to use config/default.
+        db_path: Explicit database path, or None to use the resolver.
 
     Returns:
-        Absolute path to the SQLite database file.
+        Absolute path to the SQLite database file; its folder exists (a new
+        data folder is created owner-only).
     """
-    extension_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-
     if db_path is None:
-        try:
-            try:
-                from ..py.config import PromptManagerConfig
-            except ImportError:
-                from py.config import PromptManagerConfig
-
-            db_path = PromptManagerConfig.DEFAULT_DB_PATH
-        except Exception:
-            db_path = "prompts.db"
-
-    if not os.path.isabs(db_path):
+        db_path = resolve_library_location().db_path
+    elif not os.path.isabs(db_path):
+        extension_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
         db_path = os.path.normpath(os.path.join(extension_root, db_path))
 
-    # Ensure parent directory exists for custom paths
     parent = os.path.dirname(db_path)
     if parent:
-        os.makedirs(parent, exist_ok=True)
+        library_location.ensure_private_dir(parent)
 
     return db_path
 
diff --git a/py/config.py b/py/config.py
index 18f94f10..11bcdf28 100644
--- a/py/config.py
+++ b/py/config.py
@@ -36,12 +36,14 @@ from typing import Any, Dict, List, Optional, Tuple  # noqa: E402
 # Import logging system
 try:
     from ..utils.logging_config import get_logger
+    from ..utils import library_location
 except ImportError:
     import sys
 
     current_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
     sys.path.insert(0, current_dir)
     from utils.logging_config import get_logger
+    from utils import library_location
 
 # Initialize logger for config operations
 config_logger = get_logger("prompt_manager.config")
@@ -663,6 +665,10 @@ class PromptManagerConfig:
     # database first (System › Backup & export › Recovery policy, #249 S6).
     SAFETY_BACKUP = True
 
+    # "Keep it here" (#249 S6b): the user chose to keep a node-folder library
+    # where it is, so the workspace stops offering to move it.
+    KEEP_LIBRARY_IN_NODE_FOLDER = False
+
     @classmethod
     def max_worker_threads(cls) -> int:
         """Largest accepted worker-thread count: the detected core count."""
@@ -718,6 +724,7 @@ class PromptManagerConfig:
                 "worker_threads": cls.WORKER_THREADS,
             },
             "maintenance": {"safety_backup": cls.SAFETY_BACKUP},
+            "library": {"keep_in_node_folder": cls.KEEP_LIBRARY_IN_NODE_FOLDER},
             "gallery": GalleryConfig.get_config(),
             "integrations": IntegrationConfig.get_config(),
             "autotag": AutotagConfig.get_config(),
@@ -727,14 +734,12 @@ class PromptManagerConfig:
     def get_config_path(cls) -> str:
         """Path of the persisted config.json.
 
-        Honours ``PROMPT_MANAGER_CONFIG_PATH`` when set; otherwise the file
-        lives at the repository root next to ``pyproject.toml``.
+        Honours ``PROMPT_MANAGER_CONFIG_PATH`` when set; otherwise it lives in
+        the library's data folder (``utils.library_location``): the node
+        folder for a library that was not moved, else ComfyUI's
+        ``user/__promptmanager``.
         """
-        override = os.environ.get(CONFIG_PATH_ENV, "").strip()
-        if override:
-            return override
-        repo_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-        return os.path.join(repo_root, "config.json")
+        return library_location.config_location()[0]
 
     @classmethod
     def load_from_file(cls, config_path: Optional[str] = None):
@@ -859,6 +864,12 @@ class PromptManagerConfig:
         ):
             cls.SAFETY_BACKUP = maintenance["safety_backup"]
 
+        library = new_config.get("library", {})
+        if isinstance(library, dict) and isinstance(
+            library.get("keep_in_node_folder"), bool
+        ):
+            cls.KEEP_LIBRARY_IN_NODE_FOLDER = library["keep_in_node_folder"]
+
         # Update gallery config
         if "gallery" in new_config:
             GalleryConfig.update_config(new_config["gallery"])
diff --git a/py/lora_utils.py b/py/lora_utils.py
index 454c182a..83091dbe 100644
--- a/py/lora_utils.py
+++ b/py/lora_utils.py
@@ -567,10 +567,21 @@ def download_civitai_images(
 
 
 def get_lora_image_cache_dir() -> Path:
-    """Get the directory used to cache downloaded LoRA example images."""
-    # Store in the extension's own directory
+    """Get the directory used to cache downloaded LoRA example images.
+
+    ``<data folder>/data/lora_images`` (``utils.library_location``): the node
+    folder for a library that was not moved, else ComfyUI's
+    ``user/__promptmanager``.
+    """
+    try:
+        from ..utils import library_location
+    except ImportError:
+        from utils import library_location
+
     ext_root = Path(__file__).resolve().parent.parent
-    cache = ext_root / "data" / "lora_images"
+    cache = Path(
+        library_location.cache_dir("lora_images", extension_root=str(ext_root))
+    )
     cache.mkdir(parents=True, exist_ok=True)
     return cache
 
diff --git a/tests/test_library_location.py b/tests/test_library_location.py
new file mode 100644
index 00000000..44202bbd
--- /dev/null
+++ b/tests/test_library_location.py
@@ -0,0 +1,326 @@
+"""Where the library lives (#249 S6b): the one resolver, ``utils/library_location``.
+
+Every case builds its own extension root (the node folder) and ComfyUI user
+folder in a temp directory and hands the resolver a fake ``folder_paths``, so
+no test reads the real environment, the repository's own files or ComfyUI.
+"""
+
+import json
+import os
+import sys
+import tempfile
+import types
+import unittest
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from utils import library_location as ll  # noqa: E402
+
+
+def _touch(path, data=b"x"):
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    with open(path, "wb") as handle:
+        handle.write(data)
+
+
+def _folder_paths(base, *, helper=True):
+    """A ComfyUI ``folder_paths`` stand-in rooted at ``base``."""
+    module = types.SimpleNamespace(base_path=base)
+    for name in ("output", "input", "temp", "user"):
+        directory = os.path.join(base, name)
+        os.makedirs(directory, exist_ok=True)
+        setattr(module, f"get_{name}_directory", lambda d=directory: d)
+    if helper:
+        module.get_system_user_directory = lambda name="system": os.path.join(
+            base, "user", "__" + name
+        )
+    return module
+
+
+class _Case(unittest.TestCase):
+    def setUp(self):
+        self._tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self._tmp.cleanup)
+        self.base = os.path.realpath(self._tmp.name)
+        self.comfy = os.path.join(self.base, "ComfyUI")
+        self.ext = os.path.join(self.comfy, "custom_nodes", "ComfyUI_PromptManager")
+        os.makedirs(self.ext)
+        self.fp = _folder_paths(self.comfy)
+        self.default_dir = os.path.join(self.comfy, "user", "__promptmanager")
+        ll.clear_override()
+        self.addCleanup(ll.clear_override)
+
+    def resolve(self, default_path=None, environ=None, **kwargs):
+        kwargs.setdefault("folder_paths", self.fp)
+        return ll.resolve_library(
+            default_path, environ=environ or {}, extension_root=self.ext, **kwargs
+        )
+
+    def config_location(self, environ=None, **kwargs):
+        kwargs.setdefault("folder_paths", self.fp)
+        return ll.config_location(
+            environ=environ or {}, extension_root=self.ext, **kwargs
+        )
+
+
+class TestDefaultDataFolder(_Case):
+    def test_uses_comfyui_system_user_helper(self):
+        self.assertEqual(ll.default_data_dir(self.fp), self.default_dir)
+
+    def test_falls_back_to_user_directory_without_helper(self):
+        fp = _folder_paths(self.comfy, helper=False)
+        self.assertEqual(ll.default_data_dir(fp), self.default_dir)
+
+    def test_none_outside_comfyui(self):
+        self.assertIsNone(ll.default_data_dir(None))
+        self.assertIsNone(ll.default_data_dir(types.SimpleNamespace()))
+
+
+class TestResolutionOrder(_Case):
+    def test_new_install_uses_default_folder_and_creates_nothing_in_node_folder(self):
+        location = self.resolve()
+        self.assertEqual(location.source, ll.SOURCE_DEFAULT)
+        self.assertEqual(location.db_path, os.path.join(self.default_dir, "prompts.db"))
+        self.assertEqual(
+            location.config_path, os.path.join(self.default_dir, "config.json")
+        )
+        self.assertFalse(location.movable)
+        self.assertEqual(os.listdir(self.ext), [])
+
+    def test_legacy_node_folder_library_stays_in_use(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        location = self.resolve()
+        self.assertEqual(location.source, ll.SOURCE_NODE_FOLDER)
+        self.assertEqual(location.db_path, os.path.join(self.ext, "prompts.db"))
+        self.assertEqual(location.config_path, os.path.join(self.ext, "config.json"))
+        self.assertEqual(location.data_dir, self.ext)
+        self.assertTrue(location.movable)
+        self.assertEqual(location.target_dir, self.default_dir)
+
+    def test_legacy_wins_over_an_unmarked_default_folder_library(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        _touch(os.path.join(self.default_dir, "prompts.db"))
+        self.assertEqual(self.resolve().source, ll.SOURCE_NODE_FOLDER)
+
+    def test_explicit_default_path_is_honoured_as_today(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        elsewhere = os.path.join(self.base, "elsewhere", "pm.db")
+        location = self.resolve(elsewhere)
+        self.assertEqual(location.source, ll.SOURCE_CONFIG)
+        self.assertEqual(location.db_path, elsewhere)
+        self.assertFalse(location.movable)
+        relative = self.resolve("data/my.db")
+        self.assertEqual(relative.db_path, os.path.join(self.ext, "data", "my.db"))
+        self.assertEqual(relative.source, ll.SOURCE_CONFIG)
+
+    def test_default_setting_value_is_not_explicit(self):
+        for value in (None, "", "prompts.db"):
+            self.assertEqual(self.resolve(value).source, ll.SOURCE_DEFAULT, value)
+
+    def test_environment_folder_wins(self):
+        data = os.path.join(self.base, "pm-data")
+        location = self.resolve(environ={ll.DATA_DIR_ENV: data})
+        self.assertEqual(location.source, ll.SOURCE_ENVIRONMENT)
+        self.assertEqual(location.db_path, os.path.join(data, "prompts.db"))
+        self.assertEqual(location.config_path, os.path.join(data, "config.json"))
+
+    def test_environment_folder_with_a_library_wins_over_legacy(self):
+        data = os.path.join(self.base, "pm-data")
+        _touch(os.path.join(data, "prompts.db"))
+        _touch(os.path.join(self.ext, "prompts.db"))
+        location = self.resolve(environ={ll.DATA_DIR_ENV: data})
+        self.assertEqual(location.source, ll.SOURCE_ENVIRONMENT)
+
+    def test_empty_environment_folder_never_replaces_a_legacy_library(self):
+        data = os.path.join(self.base, "pm-data")
+        _touch(os.path.join(self.ext, "prompts.db"))
+        location = self.resolve(environ={ll.DATA_DIR_ENV: data})
+        self.assertEqual(location.source, ll.SOURCE_NODE_FOLDER)
+        self.assertEqual(location.db_path, os.path.join(self.ext, "prompts.db"))
+        self.assertEqual(location.problem, "data-dir-empty")
+        self.assertEqual(location.target_dir, data)
+        self.assertTrue(location.movable)
+
+    def test_config_path_environment_is_honoured(self):
+        custom = os.path.join(self.base, "cfg", "custom.json")
+        location = self.resolve(environ={ll.CONFIG_PATH_ENV: custom})
+        self.assertEqual(location.config_path, custom)
+        self.assertEqual(location.source, ll.SOURCE_DEFAULT)
+
+    def test_without_comfyui_the_node_folder_is_used(self):
+        location = self.resolve(folder_paths=None)
+        self.assertEqual(location.source, ll.SOURCE_NODE_FOLDER)
+        self.assertEqual(location.db_path, os.path.join(self.ext, "prompts.db"))
+        self.assertFalse(location.movable)
+
+    def test_override_after_a_live_move_wins(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        moved = ll.LibraryLocation(
+            source=ll.SOURCE_DEFAULT,
+            db_path=os.path.join(self.default_dir, "prompts.db"),
+            config_path=os.path.join(self.default_dir, "config.json"),
+            data_dir=self.default_dir,
+            target_dir=self.default_dir,
+        )
+        ll.switch_to(moved)
+        self.assertEqual(self.resolve(), moved)
+        self.assertEqual(self.config_location(), (moved.config_path, moved.data_dir))
+        ll.clear_override()
+        self.assertEqual(self.resolve().source, ll.SOURCE_NODE_FOLDER)
+
+
+class TestMarker(_Case):
+    def _marker(self, directory, state):
+        os.makedirs(directory, exist_ok=True)
+        with open(os.path.join(directory, ll.MARKER_NAME), "w") as handle:
+            json.dump({"version": 1, "state": state}, handle)
+
+    def test_moved_marker_wins_while_the_old_file_was_not_renamed_yet(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        _touch(os.path.join(self.default_dir, "prompts.db"))
+        self._marker(self.default_dir, "moved")
+        location = self.resolve()
+        self.assertEqual(location.source, ll.SOURCE_DEFAULT)
+        self.assertEqual(location.db_path, os.path.join(self.default_dir, "prompts.db"))
+        self.assertEqual(
+            location.config_path, os.path.join(self.default_dir, "config.json")
+        )
+
+    def test_pending_marker_keeps_the_old_library(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        _touch(os.path.join(self.default_dir, "prompts.db"))
+        self._marker(self.default_dir, "pending")
+        self.assertEqual(self.resolve().source, ll.SOURCE_NODE_FOLDER)
+        data = os.path.join(self.base, "pm-data")
+        _touch(os.path.join(data, "prompts.db"))
+        self._marker(data, "pending")
+        location = self.resolve(environ={ll.DATA_DIR_ENV: data})
+        self.assertEqual(location.source, ll.SOURCE_NODE_FOLDER)
+        self.assertEqual(location.problem, "move-unfinished")
+
+    def test_unreadable_marker_is_not_trusted(self):
+        _touch(os.path.join(self.ext, "prompts.db"))
+        _touch(os.path.join(self.default_dir, "prompts.db"))
+        _touch(os.path.join(self.default_dir, ll.MARKER_NAME), b"{not json")
+        self.assertEqual(self.resolve().source, ll.SOURCE_NODE_FOLDER)
+        self.assertEqual(ll.read_marker(self.default_dir), {})
+
+    def test_renamed_old_file_is_never_picked(self):
+        _touch(os.path.join(self.ext, "prompts.db.moved-to-__promptmanager"))
+        _touch(os.path.join(self.default_dir, "prompts.db"))
+        self.assertEqual(self.resolve().source, ll.SOURCE_DEFAULT)
+
+
+class TestConfigLocation(_Case):
+    def test_legacy_config_without_a_database_keeps_being_read(self):
+        _touch(os.path.join(self.ext, "config.json"), b"{}")
+        path, data_dir = self.config_location()
+        self.assertEqual(path, os.path.join(self.ext, "config.json"))
+        self.assertEqual(data_dir, self.ext)
+
+    def test_legacy_config_alone_never_puts_a_new_database_in_the_node_folder(self):
+        _touch(os.path.join(self.ext, "config.json"), b"{}")
+        location = self.resolve()
+        self.assertEqual(location.db_path, os.path.join(self.default_dir, "prompts.db"))
+        self.assertEqual(location.config_path, os.path.join(self.ext, "config.json"))
+        self.assertFalse(location.movable)
+
+    def test_new_install_reads_config_from_the_data_folder(self):
+        path, data_dir = self.config_location()
+        self.assertEqual(path, os.path.join(self.default_dir, "config.json"))
+        self.assertEqual(data_dir, self.default_dir)
+
+    def test_logs_and_cache_follow_the_data_folder(self):
+        self.assertEqual(
+            ll.logs_dir(environ={}, extension_root=self.ext, folder_paths=self.fp),
+            os.path.join(self.default_dir, "logs"),
+        )
+        _touch(os.path.join(self.ext, "prompts.db"))
+        self.assertEqual(
+            ll.logs_dir(environ={}, extension_root=self.ext, folder_paths=self.fp),
+            os.path.join(self.ext, "logs"),
+        )
+        self.assertEqual(
+            ll.cache_dir(
+                "lora_images", environ={}, extension_root=self.ext, folder_paths=self.fp
+            ),
+            os.path.join(self.ext, "data", "lora_images"),
+        )
+
+
+class TestDataDirValidation(_Case):
+    def problem(self, path, **kwargs):
+        kwargs.setdefault("folder_paths", self.fp)
+        return ll.data_dir_problem(path, **kwargs)
+
+    def test_valid_folder(self):
+        self.assertIsNone(self.problem(os.path.join(self.base, "pm-data")))
+        self.assertIsNone(self.problem(self.default_dir))
+
+    def test_relative_and_empty_paths_are_refused(self):
+        self.assertEqual(self.problem("pm-data"), "data-dir-not-absolute")
+        self.assertEqual(self.problem(""), "data-dir-not-absolute")
+
+    def test_served_folders_are_refused(self):
+        for name in ("output", "input", "temp"):
+            inside = os.path.join(self.comfy, name, "pm")
+            self.assertEqual(self.problem(inside), "data-dir-served", name)
+        self.assertEqual(
+            self.problem(os.path.join(self.comfy, "output")), "data-dir-served"
+        )
+
+    def test_public_user_folder_is_refused_but_system_users_are_fine(self):
+        public = os.path.join(self.comfy, "user", "default", "pm")
+        self.assertEqual(self.problem(public), "data-dir-served")
+        self.assertIsNone(self.problem(os.path.join(self.comfy, "user", "__pm")))
+
+    def test_gallery_source_is_refused(self):
+        source = os.path.join(self.base, "gallery")
+        os.makedirs(source)
+        self.assertEqual(
+            self.problem(os.path.join(source, "pm"), gallery_roots=[source]),
+            "data-dir-served",
+        )
+        self.assertEqual(
+            self.problem(
+                os.path.join(source, "pm"),
+                environ={ll.EXTRA_GALLERY_ROOTS_ENV: source},
+            ),
+            "data-dir-served",
+        )
+
+    def test_symlink_into_output_is_refused(self):
+        link = os.path.join(self.base, "link-to-output")
+        try:
+            os.symlink(os.path.join(self.comfy, "output"), link)
+        except (OSError, NotImplementedError):
+            self.skipTest("symlinks are not available")
+        self.assertEqual(self.problem(os.path.join(link, "pm")), "data-dir-served")
+
+    def test_case_variant_spelling_of_output_is_refused_where_the_volume_folds_case(
+        self,
+    ):
+        upper = os.path.join(self.comfy, "OUTPUT")
+        if not os.path.isdir(upper):
+            self.skipTest("this volume is case-sensitive")
+        self.assertEqual(self.problem(os.path.join(upper, "pm")), "data-dir-served")
+
+    def test_invalid_environment_folder_is_ignored_with_a_problem(self):
+        inside = os.path.join(self.comfy, "output", "pm")
+        location = self.resolve(environ={ll.DATA_DIR_ENV: inside})
+        self.assertEqual(location.source, ll.SOURCE_DEFAULT)
+        self.assertEqual(location.problem, "data-dir-served")
+        self.assertFalse(os.path.exists(inside))
+        relative = self.resolve(environ={ll.DATA_DIR_ENV: "relative/dir"})
+        self.assertEqual(relative.problem, "data-dir-not-absolute")
+
+
+class TestSameFolder(_Case):
+    def test_same_folder_follows_links_and_case(self):
+        self.assertTrue(ll.same_folder(self.ext, self.ext + os.sep))
+        self.assertFalse(ll.same_folder(self.ext, self.default_dir))
+        self.assertFalse(ll.same_folder(self.ext, os.path.join(self.base, "missing")))
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_library_location_wiring.py b/tests/test_library_location_wiring.py
new file mode 100644
index 00000000..d2fa31af
--- /dev/null
+++ b/tests/test_library_location_wiring.py
@@ -0,0 +1,169 @@
+"""Every data path asks the one resolver (#249 S6b).
+
+The database, the diagnostics database, config.json, the logs and the LoRA
+image cache all follow ``utils.library_location``: a folder named by
+``PROMPT_MANAGER_DATA_DIR`` (and, after a live move, the switched location).
+"""
+
+import os
+import pathlib
+import sys
+import tempfile
+import types
+import unittest
+import unittest.mock as mock
+from unittest.mock import MagicMock
+
+_mock_server = MagicMock()
+_mock_server.PromptServer.instance.routes = MagicMock()
+sys.modules.setdefault("server", _mock_server)
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from utils import library_location as ll  # noqa: E402
+
+
+class _EnvCase(unittest.TestCase):
+    def setUp(self):
+        self._tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self._tmp.cleanup)
+        base = os.path.realpath(self._tmp.name)
+        self.data = os.path.join(base, "pm-data")
+        patcher = mock.patch.dict(
+            os.environ,
+            {ll.DATA_DIR_ENV: self.data, ll.CONFIG_PATH_ENV: ""},
+        )
+        patcher.start()
+        self.addCleanup(patcher.stop)
+        # This test's own ComfyUI folders (the shared stub serves the system
+        # temp folder as "output", which would rightly refuse self.data).
+        comfy = os.path.join(base, "ComfyUI")
+        fp = types.ModuleType("folder_paths")
+        for name in ("output", "input", "temp", "user"):
+            setattr(fp, f"get_{name}_directory", lambda n=name: os.path.join(comfy, n))
+        modules = mock.patch.dict(sys.modules, {"folder_paths": fp})
+        modules.start()
+        self.addCleanup(modules.stop)
+        ll.clear_override()
+        self.addCleanup(ll.clear_override)
+
+
+class TestDatabasePath(_EnvCase):
+    def test_database_follows_the_data_folder(self):
+        from database.operations import _resolve_db_path
+
+        with mock.patch.dict(sys.modules, {"py.config": None}):
+            path = _resolve_db_path(None)
+        self.assertEqual(path, os.path.join(self.data, "prompts.db"))
+        self.assertTrue(os.path.isdir(self.data))
+        if os.name == "posix":
+            self.assertEqual(os.stat(self.data).st_mode & 0o777, 0o700)
+
+    def test_diagnostics_use_the_same_resolver(self):
+        from database.operations import _resolve_db_path
+        from utils.diagnostics import GalleryDiagnostics
+
+        with mock.patch.dict(sys.modules, {"py.config": None}):
+            self.assertEqual(GalleryDiagnostics._resolve_db_path(), _resolve_db_path())
+
+    def test_switched_location_wins(self):
+        from database.operations import _resolve_db_path
+
+        moved = ll.LibraryLocation(
+            ll.SOURCE_DEFAULT,
+            os.path.join(self.data, "moved", "prompts.db"),
+            os.path.join(self.data, "moved", "config.json"),
+            os.path.join(self.data, "moved"),
+        )
+        ll.switch_to(moved)
+        self.assertEqual(_resolve_db_path(None), moved.db_path)
+
+
+class TestConfigPath(_EnvCase):
+    def test_config_json_follows_the_data_folder(self):
+        from py.config import PromptManagerConfig
+
+        self.assertEqual(
+            PromptManagerConfig.get_config_path(),
+            os.path.join(self.data, "config.json"),
+        )
+
+    def test_explicit_config_path_still_wins(self):
+        from py.config import PromptManagerConfig
+
+        custom = os.path.join(self.data, "elsewhere.json")
+        with mock.patch.dict(os.environ, {ll.CONFIG_PATH_ENV: custom}):
+            self.assertEqual(PromptManagerConfig.get_config_path(), custom)
+
+    def test_keep_choice_round_trips(self):
+        from py.config import PromptManagerConfig
+
+        original = PromptManagerConfig.KEEP_LIBRARY_IN_NODE_FOLDER
+        self.addCleanup(
+            setattr, PromptManagerConfig, "KEEP_LIBRARY_IN_NODE_FOLDER", original
+        )
+        PromptManagerConfig.update_config({"library": {"keep_in_node_folder": True}})
+        self.assertTrue(PromptManagerConfig.KEEP_LIBRARY_IN_NODE_FOLDER)
+        self.assertEqual(
+            PromptManagerConfig.get_config()["library"], {"keep_in_node_folder": True}
+        )
+        PromptManagerConfig.update_config({"library": {"keep_in_node_folder": "yes"}})
+        self.assertTrue(PromptManagerConfig.KEEP_LIBRARY_IN_NODE_FOLDER)
+
+
+class TestLogsAndCache(_EnvCase):
+    def test_logs_go_to_the_data_folder(self):
+        from utils import logging_config
+        from utils.logging_config import PromptManagerLogger
+
+        manager = object.__new__(PromptManagerLogger)
+        self.addCleanup(self._close, manager)
+        manager.__init__()
+        self.assertEqual(manager.log_dir, pathlib.Path(self.data, "logs"))
+        self.assertTrue(manager.log_dir.is_dir())
+        self.assertIs(logging_config.library_location, ll)
+
+    @staticmethod
+    def _close(manager):
+        import logging
+
+        for handler in logging.getLogger("prompt_manager").handlers[:]:
+            if getattr(handler, "_prompt_manager_owned", False):
+                handler.close()
+        try:
+            from utils.logging_config import get_logger_manager
+
+            get_logger_manager()._setup_loggers()
+        except Exception:
+            pass
+
+    def test_lora_image_cache_follows_the_data_folder(self):
+        from py import lora_utils
+
+        cache = lora_utils.get_lora_image_cache_dir()
+        self.assertEqual(cache, pathlib.Path(self.data, "data", "lora_images"))
+
+
+class TestNodeFolderUnchangedForLegacyInstalls(unittest.TestCase):
+    """A node folder that holds the library keeps every path where it was."""
+
+    def test_legacy_paths(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            ext = os.path.join(tmp, "ext")
+            os.makedirs(ext)
+            open(os.path.join(ext, "prompts.db"), "wb").close()
+            fp = types.SimpleNamespace(
+                get_user_directory=lambda: os.path.join(tmp, "u")
+            )
+            location = ll.resolve_library(
+                None, environ={}, extension_root=ext, folder_paths=fp
+            )
+            self.assertEqual(location.db_path, os.path.join(ext, "prompts.db"))
+            self.assertEqual(
+                ll.logs_dir(environ={}, extension_root=ext, folder_paths=fp),
+                os.path.join(ext, "logs"),
+            )
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/utils/diagnostics.py b/utils/diagnostics.py
index 094d81c1..7d1aa769 100644
--- a/utils/diagnostics.py
+++ b/utils/diagnostics.py
@@ -69,8 +69,8 @@ class GalleryDiagnostics:
 
         Args:
             db_path: Path to the SQLite database file to diagnose.
-                     If None, resolves from config.json or defaults to
-                     prompts.db in the extension root.
+                     If None, the library's database (see
+                     ``utils.library_location``).
         """
         if db_path is None:
             db_path = self._resolve_db_path()
@@ -79,18 +79,12 @@ class GalleryDiagnostics:
 
     @staticmethod
     def _resolve_db_path() -> str:
-        """Resolve database path from config, matching PromptDatabase logic."""
-        extension_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+        """The library's database: the same resolver as PromptDatabase."""
         try:
-            from py.config import PromptManagerConfig
-
-            db_path = PromptManagerConfig.DEFAULT_DB_PATH
-        except Exception:
-            db_path = "prompts.db"
-
-        if not os.path.isabs(db_path):
-            db_path = os.path.normpath(os.path.join(extension_root, db_path))
-        return db_path
+            from ..database.operations import resolve_library_location
+        except ImportError:
+            from database.operations import resolve_library_location
+        return resolve_library_location().db_path
 
     def run_full_diagnostic(self) -> Dict[str, Any]:
         """Run a complete diagnostic check.
diff --git a/utils/library_location.py b/utils/library_location.py
new file mode 100644
index 00000000..f5b1797b
--- /dev/null
+++ b/utils/library_location.py
@@ -0,0 +1,418 @@
+"""Where the library lives (#249 S6b): the one resolver for every data path.
+
+The library is ``prompts.db``, ``config.json`` (it can hold the CivitAI key),
+the safety backups beside the database, the logs and the LoRA image cache.
+Inside the node folder an uninstall, a reinstall or a folder-replacing update
+deletes it, so new installs keep it in ComfyUI's system user folder
+``user/__promptmanager`` (``folder_paths.get_system_user_directory``), which
+ComfyUI's ``/userdata`` HTTP API refuses to serve.
+
+Resolution order (``resolve_library``):
+
+1. ``PROMPT_MANAGER_DATA_DIR``: an absolute folder outside every folder
+   ComfyUI or Prompt Manager serves. It is used when it holds a library or
+   when no node-folder library exists; an empty one never replaces a
+   node-folder library (that one stays in use, and Move library targets the
+   environment folder). An invalid value is ignored and reported.
+2. An explicit ``database.default_path`` in config.json, honoured as before
+   (a relative path is relative to the node folder). ``PROMPT_MANAGER_CONFIG_PATH``
+   still names config.json itself.
+3. The default data folder once a move finished there (its marker says
+   ``moved``), even before the old file was renamed.
+4. A node-folder ``prompts.db`` that was not moved: it stays in use until the
+   user moves it.
+5. The default data folder (new installs). Outside ComfyUI (no
+   ``folder_paths``) the node folder, as before.
+
+Nothing here moves, copies or creates data: it only reads the file system.
+After a live move the process uses ``switch_to``'s location until restart.
+This module imports only the standard library, so the logger can use it.
+"""
+
+import json
+import os
+import threading
+from dataclasses import dataclass
+from typing import Iterable, List, Mapping, Optional, Tuple
+
+DATA_DIR_ENV = "PROMPT_MANAGER_DATA_DIR"
+CONFIG_PATH_ENV = "PROMPT_MANAGER_CONFIG_PATH"
+EXTRA_GALLERY_ROOTS_ENV = "PROMPT_MANAGER_EXTRA_GALLERY_ROOTS"
+SYSTEM_USER_NAME = "promptmanager"
+SYSTEM_USER_PREFIX = "__"
+DATABASE_NAME = "prompts.db"
+CONFIG_NAME = "config.json"
+MARKER_NAME = "library-location.json"
+# config.json has always written its default; that value is not a choice.
+DEFAULT_DB_SETTING = "prompts.db"
+
+SOURCE_ENVIRONMENT = "environment"
+SOURCE_CONFIG = "config"
+SOURCE_NODE_FOLDER = "node_folder"
+SOURCE_DEFAULT = "default"
+SOURCES = (SOURCE_ENVIRONMENT, SOURCE_CONFIG, SOURCE_NODE_FOLDER, SOURCE_DEFAULT)
+
+MARKER_PENDING = "pending"
+MARKER_MOVED = "moved"
+
+EXTENSION_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+_UNSET = object()
+_override_lock = threading.Lock()
+_override: Optional["LibraryLocation"] = None
+
+
+@dataclass(frozen=True)
+class LibraryLocation:
+    """Where the library is and why.
+
+    ``target_dir`` is where Move library would put it (None outside ComfyUI);
+    ``problem`` is a code for something the user should know (an invalid or
+    empty ``PROMPT_MANAGER_DATA_DIR``, a move that did not finish).
+    """
+
+    source: str
+    db_path: str
+    config_path: str
+    data_dir: str
+    target_dir: Optional[str] = None
+    problem: Optional[str] = None
+
+    @property
+    def movable(self) -> bool:
+        return self.source == SOURCE_NODE_FOLDER and self.target_dir is not None
+
+
+def import_folder_paths():
+    """ComfyUI's ``folder_paths`` module, or None outside ComfyUI."""
+    try:
+        import folder_paths
+    except ImportError:
+        return None
+    return folder_paths
+
+
+def _folder_paths(value):
+    return import_folder_paths() if value is _UNSET else value
+
+
+def _call(module, name, *args) -> Optional[str]:
+    getter = getattr(module, name, None)
+    if not callable(getter):
+        return None
+    try:
+        value = getter(*args)
+    except Exception:  # an older or broken host: treat the folder as unknown
+        return None
+    return str(value) if value else None
+
+
+def default_data_dir(folder_paths=_UNSET) -> Optional[str]:
+    """``user/__promptmanager``, or None outside ComfyUI.
+
+    ComfyUI builds without ``get_system_user_directory`` get the same folder
+    joined by hand.
+    """
+    module = _folder_paths(folder_paths)
+    if module is None:
+        return None
+    folder = _call(module, "get_system_user_directory", SYSTEM_USER_NAME)
+    if folder:
+        return os.path.abspath(folder)
+    user = _call(module, "get_user_directory")
+    if not user:
+        return None
+    return os.path.abspath(os.path.join(user, SYSTEM_USER_PREFIX + SYSTEM_USER_NAME))
+
+
+def _identity(path: str) -> Optional[Tuple[int, int]]:
+    try:
+        stat = os.stat(path)
+    except (OSError, ValueError):
+        return None
+    return (stat.st_dev, stat.st_ino)
+
+
+def same_folder(first: str, second: str) -> bool:
+    """Whether two spellings name one existing folder (links and case folded)."""
+    one, two = _identity(first), _identity(second)
+    if one is None or two is None:
+        return False
+    if one[1] == 0:  # no file id on this volume: compare the spelling
+        return _spelling(first) == _spelling(second)
+    return one == two
+
+
+def _spelling(path: str) -> str:
+    return os.path.normcase(os.path.realpath(path))
+
+
+def _existing_ancestors(path: str) -> List[str]:
+    """``path`` (resolved) and its parents that exist, nearest first."""
+    current = os.path.realpath(path)
+    found = []
+    while True:
+        if os.path.isdir(current):
+            found.append(current)
+        parent = os.path.dirname(current)
+        if parent == current:
+            return found
+        current = parent
+
+
+def _inside_any(path: str, folders: Iterable[str]) -> bool:
+    """Whether ``path`` is one of ``folders`` or below one.
+
+    Compared by spelling (realpath + normcase) and by file identity of every
+    existing ancestor, so symlinks and case-insensitive volumes (Windows,
+    macOS) cannot hide a served folder.
+    """
+    folders = [folder for folder in folders if folder]
+    if not folders:
+        return False
+    spelling = _spelling(path)
+    sep = os.path.sep
+    for folder in folders:
+        root = _spelling(folder)
+        if spelling == root or spelling.startswith(root.rstrip(sep) + sep):
+            return True
+    identities = {_identity(folder) for folder in folders}
+    identities.discard(None)
+    identities = {item for item in identities if item[1] != 0}
+    return any(_identity(a) in identities for a in _existing_ancestors(path))
+
+
+def _served_folders(module, environ, gallery_roots) -> List[str]:
+    """Folders whose files ComfyUI or Prompt Manager hand out over HTTP."""
+    folders = []
+    if module is not None:
+        for name in (
+            "get_output_directory",
+            "get_input_directory",
+            "get_temp_directory",
+        ):
+            folder = _call(module, name)
+            if folder:
+                folders.append(folder)
+    extra = (environ or {}).get(EXTRA_GALLERY_ROOTS_ENV, "")
+    folders.extend(part for part in extra.split(os.pathsep) if part.strip())
+    folders.extend(str(root) for root in gallery_roots or () if root)
+    return folders
+
+
+def _in_public_user_folder(path: str, module) -> bool:
+    """Whether ``path`` lies in a ``/userdata``-served user folder (not ``__``)."""
+    user = _call(module, "get_user_directory") if module is not None else None
+    if not user:
+        return False
+    if not _inside_any(path, [user]) or same_folder(path, user):
+        return False
+    real_user = _spelling(user)
+    relative = os.path.relpath(_spelling(path), real_user)
+    first = relative.split(os.sep, 1)[0]
+    if first.startswith(os.pardir):
+        # Reached through a link or another spelling: judge by identity.
+        for ancestor in _existing_ancestors(path):
+            if same_folder(os.path.dirname(ancestor), user):
+                first = os.path.basename(ancestor)
+                break
+        else:
+            return False
+    return not first.startswith(SYSTEM_USER_PREFIX)
+
+
+def data_dir_problem(
+    path, *, folder_paths=_UNSET, environ=None, gallery_roots=()
+) -> Optional[str]:
+    """Why ``path`` cannot hold the library, as a code, or None.
+
+    ``data-dir-not-absolute``: empty or relative. ``data-dir-served``: inside
+    ComfyUI's output, input or temp folder, a public user folder, an extra
+    gallery root or a gallery source (their files are served over HTTP).
+    """
+    if not isinstance(path, str) or not path.strip() or not os.path.isabs(path):
+        return "data-dir-not-absolute"
+    module = _folder_paths(folder_paths)
+    if _inside_any(path, _served_folders(module, environ, gallery_roots)):
+        return "data-dir-served"
+    if _in_public_user_folder(path, module):
+        return "data-dir-served"
+    return None
+
+
+def read_marker(directory: Optional[str]) -> dict:
+    """The move marker in ``directory``, or ``{}`` when absent or unreadable."""
+    if not directory:
+        return {}
+    try:
+        with open(os.path.join(directory, MARKER_NAME), "r", encoding="utf-8") as fh:
+            data = json.load(fh)
+    except (OSError, ValueError):
+        return {}
+    if not isinstance(data, dict) or data.get("state") not in (
+        MARKER_PENDING,
+        MARKER_MOVED,
+    ):
+        return {}
+    return data
+
+
+def _marker_state(directory) -> Optional[str]:
+    return read_marker(directory).get("state")
+
+
+def switch_to(location: LibraryLocation) -> None:
+    """Use ``location`` for the rest of this process (after a live move)."""
+    global _override
+    with _override_lock:
+        _override = location
+
+
+def clear_override() -> None:
+    """Forget a live move's location (tests)."""
+    global _override
+    with _override_lock:
+        _override = None
+
+
+def current_override() -> Optional[LibraryLocation]:
+    with _override_lock:
+        return _override
+
+
+@dataclass(frozen=True)
+class _Decision:
+    data_dir: str
+    source: str
+    target_dir: Optional[str]
+    problem: Optional[str]
+    db_dir: Optional[str] = None  # when the database is not in data_dir
+
+
+def _decide(environ, extension_root, folder_paths, gallery_roots) -> _Decision:
+    """Which folder holds the library (before an explicit database path)."""
+    module = _folder_paths(folder_paths)
+    environ = os.environ if environ is None else environ
+    legacy_db = os.path.isfile(os.path.join(extension_root, DATABASE_NAME))
+    legacy = legacy_db or os.path.isfile(os.path.join(extension_root, CONFIG_NAME))
+    default = default_data_dir(module)
+    problem = None
+    env_dir = None
+    raw = environ.get(DATA_DIR_ENV, "")
+    if raw.strip():
+        problem = data_dir_problem(
+            raw.strip(),
+            folder_paths=module,
+            environ=environ,
+            gallery_roots=gallery_roots,
+        )
+        if problem is None:
+            env_dir = os.path.abspath(raw.strip())
+    target = env_dir or default
+    if env_dir is not None:
+        state = _marker_state(env_dir)
+        holds = os.path.isfile(os.path.join(env_dir, DATABASE_NAME))
+        if state != MARKER_PENDING and (holds or not legacy_db):
+            return _Decision(env_dir, SOURCE_ENVIRONMENT, env_dir, None)
+        problem = "move-unfinished" if state == MARKER_PENDING else "data-dir-empty"
+        return _Decision(extension_root, SOURCE_NODE_FOLDER, env_dir, problem)
+    if default is None:
+        return _Decision(extension_root, SOURCE_NODE_FOLDER, None, problem)
+    if _marker_state(default) == MARKER_MOVED and os.path.isfile(
+        os.path.join(default, DATABASE_NAME)
+    ):
+        return _Decision(default, SOURCE_DEFAULT, target, problem)
+    if legacy:
+        if _marker_state(default) == MARKER_PENDING:
+            problem = problem or "move-unfinished"
+        if legacy_db:
+            return _Decision(extension_root, SOURCE_NODE_FOLDER, target, problem)
+        # Only a node-folder config.json: keep reading it, but a new database
+        # never goes into the node folder.
+        return _Decision(extension_root, SOURCE_DEFAULT, target, problem, default)
+    return _Decision(default, SOURCE_DEFAULT, target, problem)
+
+
+def config_location(
+    environ=None, extension_root=None, folder_paths=_UNSET, gallery_roots=()
+) -> Tuple[str, str]:
+    """``(config.json path, data folder)``; needs no config value (no cycle)."""
+    override = current_override()
+    if override is not None:
+        return override.config_path, override.data_dir
+    environ = os.environ if environ is None else environ
+    root = extension_root or EXTENSION_ROOT
+    decision = _decide(environ, root, folder_paths, gallery_roots)
+    explicit = environ.get(CONFIG_PATH_ENV, "").strip()
+    config_path = explicit or os.path.join(decision.data_dir, CONFIG_NAME)
+    return config_path, decision.data_dir
+
+
+def is_explicit_db_setting(value) -> bool:
+    """Whether config.json's ``database.default_path`` names a chosen file."""
+    return isinstance(value, str) and value.strip() not in ("", DEFAULT_DB_SETTING)
+
+
+def resolve_library(
+    default_path=None,
+    *,
+    environ: Optional[Mapping[str, str]] = None,
+    extension_root: Optional[str] = None,
+    folder_paths=_UNSET,
+    gallery_roots=(),
+) -> LibraryLocation:
+    """The library's location now (the module docstring has the order)."""
+    override = current_override()
+    if override is not None:
+        return override
+    environ = os.environ if environ is None else environ
+    root = extension_root or EXTENSION_ROOT
+    decision = _decide(environ, root, folder_paths, gallery_roots)
+    config_path = environ.get(CONFIG_PATH_ENV, "").strip() or os.path.join(
+        decision.data_dir, CONFIG_NAME
+    )
+    if decision.source != SOURCE_ENVIRONMENT and is_explicit_db_setting(default_path):
+        db_path = default_path.strip()
+        if not os.path.isabs(db_path):
+            db_path = os.path.normpath(os.path.join(root, db_path))
+        return LibraryLocation(
+            SOURCE_CONFIG,
+            db_path,
+            config_path,
+            decision.data_dir,
+            decision.target_dir,
+            decision.problem,
+        )
+    return LibraryLocation(
+        decision.source,
+        os.path.join(decision.db_dir or decision.data_dir, DATABASE_NAME),
+        config_path,
+        decision.data_dir,
+        decision.target_dir,
+        decision.problem,
+    )
+
+
+def ensure_private_dir(path: str) -> str:
+    """Create ``path`` (and parents) if missing; a new folder is owner-only.
+
+    An existing folder is left as it is (its permissions are the user's).
+    """
+    if not os.path.isdir(path):
+        os.makedirs(path, mode=0o700, exist_ok=True)
+        if os.name == "posix":
+            try:
+                os.chmod(path, 0o700)
+            except OSError:
+                pass
+    return path
+
+
+def logs_dir(**kwargs) -> str:
+    """The folder for Prompt Manager's log files."""
+    return os.path.join(config_location(**kwargs)[1], "logs")
+
+
+def cache_dir(name: str, **kwargs) -> str:
+    """A re-creatable cache folder, ``<data folder>/data/<name>``."""
+    return os.path.join(config_location(**kwargs)[1], "data", name)
diff --git a/utils/logging_config.py b/utils/logging_config.py
index d9a62866..bb147a2e 100644
--- a/utils/logging_config.py
+++ b/utils/logging_config.py
@@ -18,6 +18,8 @@ from datetime import datetime
 from typing import Dict, Any, Optional, List
 from pathlib import Path
 
+from . import library_location
+
 
 class _OwnedRotatingFileHandler(logging.handlers.RotatingFileHandler):
     """Keep a retired owned sink closed when an in-flight record resumes."""
@@ -65,8 +67,12 @@ class PromptManagerLogger:
             return
 
         self._initialized = True
-        self.log_dir = Path(__file__).parent.parent / "logs"
-        self.log_dir.mkdir(exist_ok=True)
+        # The library's data folder (#249 S6b): the node folder for a library
+        # that was not moved, else ComfyUI's user/__promptmanager.
+        self.log_dir = Path(
+            library_location.logs_dir(extension_root=str(Path(__file__).parent.parent))
+        )
+        library_location.ensure_private_dir(str(self.log_dir))
 
         # Configuration
         self.config = {