Host Ownership of Shared Values

In the previous chapter:

• audiodeck became the host.
• audio_encode was embedded inside it.
• The UI was unified.
• Only audiodeck was enabled.

However, one important thing has not changed yet.

audio_encode is still storing its shared values in fallback storage.

Current State

Right now, shared values for audio_encode live in:

context.scene.qa_shared

So even though:

• audiodeck controls the panel
• audio_encode renders inside it

The data is still owned by generated fallback storage.

audiodeck controls the UI, but not the data.

Why This Matters

Suppose audiodeck already defines its own property group:

class AudioDeckProps(bpy.types.PropertyGroup):
    audio_path: bpy.props.StringProperty(
        name="Audio Path",
        subtype="FILE_PATH"
    )

And suppose it is registered as:

bpy.types.Scene.audiodeck_props = bpy.props.PointerProperty(
    type=AudioDeckProps
)

Now we have two places storing the same concept:

context.scene.audiodeck_props.audio_path
context.scene.qa_shared.project__audio_path

Two values. One meaning.

That duplication is unnecessary.

If audiodeck is the host, it should own the data.

The Mechanism: HostAPI

When audio_encode reads or draws a shared value, it does not directly access storage.

Instead, it calls:

host_api.get(...)
host_api.draw(...)

Until now, we were relying on the default fallback host.

Now we will provide our own.

Step 1 – Implement a Minimal HostAPI in audiodeck

Open:

audiodeck/__init__.py

Add the following class:

class AudioDeckHostAPI:

    def get(self, context, key, fallback_prop):
        if key == "project.audio_path":
            return context.scene.audiodeck_props.audio_path

        # fallback for unknown keys
        return getattr(context.scene.qa_shared, fallback_prop)

    def draw(self, layout, context, key, fallback_prop, label=None):
        if key == "project.audio_path":
            layout.prop(
                context.scene.audiodeck_props,
                "audio_path",
                text=label
            )
        else:
            layout.prop(
                context.scene.qa_shared,
                fallback_prop,
                text=label
            )

This class does two things:

• Routes "project.audio_path" into audiodeck_props.
• Falls back to generated storage for all other shared keys.

The plugin does not change. Only the host’s routing logic changes.

Step 2 – Inject the HostAPI

Modify the registration of audio_encode inside audiodeck.register():

audio_encode_ops.register(
    mode="plugin",
    host_api=AudioDeckHostAPI()
)

That is the entire ownership transfer.

What Changed?

Before:

audio_encode
    └── qa_shared

After:

audio_encode
    └── HostAPI
          └── audiodeck_props

Now:

• audio_encode reads from audiodeck storage.
• audio_encode draws audiodeck properties.
• Fallback storage remains available for other shared keys.

What Did NOT Change

• audio_encode tool script
• audio_encode shared decorator
• audio_encode operator logic
• audio_encode build process

Only audiodeck changed.

The plugin remains generated, reusable, and composable.

What You Have Now

At this point:

• UI ownership belongs to audiodeck.
• Data ownership belongs to audiodeck.
• audio_encode remains independent and reusable.
• The relationship is defined entirely through the HostAPI contract.

In the next chapter, we will make this routing scalable — so you do not have to write if key == ... for every shared value.