diff --git a/bot_bottle/db_store.py b/bot_bottle/db_store.py
index 5d4bf37..8950401 100644
--- a/bot_bottle/db_store.py
+++ b/bot_bottle/db_store.py
@@ -11,6 +11,30 @@ except ImportError:
     from migrations import TableMigrations  # type: ignore[import-not-found]  # pylint: disable=import-error,no-name-in-module
 
 
+# The single shared host state DB. All bot-bottle SQLite stores (supervise
+# queue, audit, the orchestrator registry) co-tenant this one file — the
+# TableMigrations schema_key namespaces each store's tables.
+HOST_DB_FILENAME = "bot-bottle.db"
+
+
+def host_db_path() -> Path:
+    """Path to the shared host state DB, `<bot_bottle_root>/db/bot-bottle.db`.
+
+    Kept in its own `db/` subdirectory (not directly under the root) so a
+    backend that can only bind-mount *directories* can share this one file
+    with a sidecar without exposing the root's other contents (git-gate
+    keys, per-bottle state, ...).
+
+    Resolves `bot_bottle_root` from `supervise_types` at call time (a lazy
+    import — avoids a load-time cycle, and lets a monkey-patch of
+    `supervise_types.bot_bottle_root` propagate here)."""
+    try:
+        from . import supervise_types as _st
+    except ImportError:  # flat imports inside the sidecar bundle
+        import supervise_types as _st  # type: ignore[import-not-found,no-redef]  # pylint: disable=import-error,no-name-in-module
+    return _st.bot_bottle_root() / "db" / HOST_DB_FILENAME
+
+
 class DbVersionError(Exception):
     """Raised when the on-disk schema is behind the current migration list."""
 
@@ -56,4 +80,4 @@ class DbStore:
             pass
 
 
-__all__ = ["DbStore", "DbVersionError"]
+__all__ = ["DbStore", "DbVersionError", "HOST_DB_FILENAME", "host_db_path"]
diff --git a/bot_bottle/orchestrator/registry.py b/bot_bottle/orchestrator/registry.py
index b8655ae..be835c0 100644
--- a/bot_bottle/orchestrator/registry.py
+++ b/bot_bottle/orchestrator/registry.py
@@ -35,9 +35,8 @@ import time
 from dataclasses import dataclass
 from pathlib import Path
 
-from ..db_store import DbStore
+from ..db_store import DbStore, host_db_path
 from ..migrations import TableMigrations
-from ..supervise_types import host_db_path
 
 # 256 bits of urandom, URL-safe — unguessable per-bottle identity token.
 IDENTITY_TOKEN_BYTES = 32
diff --git a/bot_bottle/supervise_types.py b/bot_bottle/supervise_types.py
index 80af0ae..1e579f0 100644
--- a/bot_bottle/supervise_types.py
+++ b/bot_bottle/supervise_types.py
@@ -5,22 +5,28 @@ Proposal, Response, AuditEntry, and host_db_path without creating a
 circular import (supervise imports from queue_store/audit_store and
 vice-versa).
 
-Patching bot_bottle_root on this module propagates through host_db_path
-because host_db_path looks up bot_bottle_root via sys.modules[__name__]
-at call time rather than capturing it at import time.
+host_db_path / HOST_DB_FILENAME now live in db_store (shared DB infra) and
+are re-exported here for the historical import path. db_store.host_db_path
+resolves bot_bottle_root from this module lazily, so patching
+supervise_types.bot_bottle_root still propagates to the DB path.
 """
 
 from __future__ import annotations
 
 import dataclasses
-import sys
 import uuid
 from dataclasses import dataclass
 from datetime import datetime, timezone
 from pathlib import Path
 
-
-HOST_DB_FILENAME = "bot-bottle.db"
+# host_db_path / HOST_DB_FILENAME now live in db_store (shared DB infra);
+# re-exported here for the historical import path. db_store resolves
+# bot_bottle_root from this module lazily, so patching
+# supervise_types.bot_bottle_root still propagates.
+try:
+    from .db_store import HOST_DB_FILENAME, host_db_path
+except ImportError:  # flat imports inside the sidecar bundle
+    from db_store import HOST_DB_FILENAME, host_db_path  # type: ignore[import-not-found,no-redef]  # pylint: disable=import-error,no-name-in-module
 
 TOOL_EGRESS_BLOCK = "egress-block"
 TOOL_EGRESS_ALLOW = "egress-allow"
@@ -47,19 +53,6 @@ def bot_bottle_root() -> Path:
     return Path.home() / ".bot-bottle"
 
 
-def host_db_path() -> Path:
-    # Look up bot_bottle_root through this module's live namespace so that
-    # monkey-patches on supervise_types.bot_bottle_root take effect.
-    #
-    # Lives in its own "db" subdirectory, not directly under
-    # bot_bottle_root(), so backends that can only bind-mount
-    # directories (macos_container's `container run --mount`, which
-    # rejects file sources with "is not a directory") can share this
-    # one file with a sidecar without also exposing bot_bottle_root()'s
-    # other contents (git-gate keys, per-bottle state, etc.).
-    return sys.modules[__name__].bot_bottle_root() / "db" / HOST_DB_FILENAME
-
-
 def _require_str(raw: dict[str, object], key: str) -> str:
     value = raw.get(key)
     if not isinstance(value, str):