# Frame boundaries: isolated worlds

<sub>**Advanced.** Hard isolation walls inside a single interpreter.</sub>

Everything so far has lived in one **aetheric frame** — the default world. A
frame is the outermost boundary in Melder: it owns its own conduits, registries,
control plane, and dynamic posture. Name a different one and you get a second
world that shares nothing with the first:

```python
tenant_a = md.Spellbook(aetheric_frame="tenant-a")
tenant_b = md.Spellbook(aetheric_frame="tenant-b")
```

Bind a distinct class in each world — a subclass per tenant is enough. A spell
ID is the SHA256 of the registered object's code (its methods, constructor,
class-level values and bases), with nothing from the bind call in it, and spell
IDs are unique across the process: the same class bound in another frame is the
same spell, and it is refused whatever `binding_name` or `spellframe` it gets.
A `unique` spell is a singleton **per frame** — not per process. Two classes,
two frames, two instances, one interpreter. To register one class in several
worlds instead, turn `process_wide_unique_spell_ids` off in the Aether
configuration before the first frame exists; spell IDs are then unique per frame.

That makes frames the natural seam for multi-tenancy, plugin isolation, and test
isolation (a fresh frame per test is a fresh world). Conduits link *within* a
frame; they do not link across one — the wall is real.

> Don't confuse the two "frames": `spellframe=` is an **address key** that
> categorizes spells *inside* a world. `aetheric_frame=` is the **world itself**.

## Three widths of category

Once you see it, the same idea repeats at three scales — each one a wider
boundary than the last:

| Scale | Categorizes | Owner |
|:---|:---|:---|
| **`spellframe`** | Spells *within* one world | The book that bound them |
| **Conduit** | Worlds of resolution, linked by contract | Each conduit owns its category |
| **`aetheric_frame`** | Entire isolated worlds | The frame itself |

Pick the narrowest one that expresses what you mean. Most systems need only the
first; large ones grow into the second; the third is for genuine isolation.

## Runnable examples

- [Frames as worlds](../examples/advanced/02-frames-as-worlds.md) — Advanced 02

[All advanced examples](../examples/advanced/index.md) · [Level contents](index.md) · [Full contents](../contents.md)

[Canonical page source](https://github.com/Synaptic724/melder/blob/90d52e0a12cb0743d62568d5a19ce954a54443bc/README.md)