feat(intel): clarify firmware/DDC flow and preserve driver metadata

- Add explanatory comments across intel driver to clarify metadata parsing.
- Ensure driver selection preserves runtime options (e.g. "intel/ddc_override:AABB")
  so driver-specific metadata is passed through to the host and available to
  drivers via host.hci_metadata.
- Ensure transport parsing regex and metadata extraction so transport/source
  metadata is populated and visible to drivers.
- Example usage: passing [driver=intel/ddc_override:AABB] will be preserved and
  can be consumed by the Intel driver to apply a DDC override blob.

bumble/drivers/__init__.py

@@ -49,6 +49,10 @@ async def get_driver_for_host(host: Host) -> Optional[Driver]:
     driver_classes: dict[str, type[Driver]] = {"rtk": rtk.Driver, "intel": intel.Driver}
     probe_list: Iterable[str]
     if driver_name := host.hci_metadata.get("driver"):
+        # The "driver" metadata may include runtime options after a '/' (for example
+        # "intel/ddc=..."). Keep only the base driver name (the portion before the
+        # first slash) so it matches a key in driver_classes (e.g. "intel").
+        driver_name = driver_name.split("/")[0]
         # Only probe a single driver
         probe_list = [driver_name]
     else:

bumble/drivers/intel.py

@@ -459,6 +459,10 @@ class Driver(common.Driver):
             == ModeOfOperation.OPERATIONAL
         ):
             logger.debug("firmware already loaded")
+            # If the firmeare is already loaded, still attempt to load any
+            # device configuration (DDC). DDC can be applied independently of a
+            # firmware reload and may contain runtime overrides or patches.
+            await self.load_ddc_if_any()
             return
 
         # We only support some platforms and variants.
@@ -598,17 +602,39 @@ class Driver(common.Driver):
         await self.reset_complete.wait()
         logger.debug("reset complete")
 
-        # Load the device config if there is one.
+        await self.load_ddc_if_any(firmware_base_name)
+
+    async def load_ddc_if_any(self, firmware_base_name: Optional[str] = None) -> None:
+        """
+        Check for and load any Device Data Configuration (DDC) blobs.
+
+        Args:
+            firmware_base_name: Base name of the selected firmware (e.g. "ibt-XXXX-YYYY").
+                                If None, don't attempt to look up a .ddc file that
+                                corresponds to the firmware image.
+        Priority:
+        1. If a ddc_override was provided via driver metadata, use it (highest priority).
+        2. Otherwise, if firmware_base_name is provided, attempt to find a .ddc file
+           that corresponds to the selected firmware image.
+        3. Finally, if a ddc_addon was provided, append/load it after the primary DDC.
+        """
+        # If an explicit DDC override was supplied, use it and skip file lookup.
         if self.ddc_override:
             logger.debug("loading overridden DDC")
             await self.load_device_config(self.ddc_override)
         else:
-            ddc_name = f"{firmware_base_name}.ddc"
-            ddc_path = _find_binary_path(ddc_name)
-            if ddc_path:
-                logger.debug(f"loading DDC from {ddc_path}")
-                ddc_data = ddc_path.read_bytes()
-                await self.load_device_config(ddc_data)
+            # Only attempt .ddc file lookup if a firmware_base_name was provided.
+            if firmware_base_name is None:
+                logger.debug(
+                    "no firmware_base_name provided; skipping .ddc file lookup"
+                )
+            else:
+                ddc_name = f"{firmware_base_name}.ddc"
+                ddc_path = _find_binary_path(ddc_name)
+                if ddc_path:
+                    logger.debug(f"loading DDC from {ddc_path}")
+                    ddc_data = ddc_path.read_bytes()
+                    await self.load_device_config(ddc_data)
         if self.ddc_addon:
             logger.debug("loading DDC addon")
             await self.load_device_config(self.ddc_addon)

bumble/transport/__init__.py

@@ -84,7 +84,12 @@ async def open_transport(name: str) -> Transport:
     scheme, *tail = name.split(':', 1)
     spec = tail[0] if tail else None
     metadata = None
-    if spec and (m := re.search(r'\[(\w+=\w+(?:,\w+=\w+)*,?)\]', spec)):
+    # If a spec is provided, check for a metadata section in square brackets.
+    # The regex captures a comma-separated list of key=value pairs (allowing an
+    # optional trailing comma). The key is matched by \w+ and the value by [^,\]]+,
+    # meaning the value may contain any character except a comma or a closing
+    # bracket (']').
+    if spec and (m := re.search(r'\[(\w+=[^,\]]+(?:,\w+=[^,\]]+)*,?)\]', spec)):
         metadata_str = m.group(1)
         if m.start() == 0:
             # <metadata><spec>