O-006, Foreign Sovereignty

The error

error[O-006]: thresholds belong to receivers. This is the entire point.

What fired

A reference to another twin's attention or membrane: any construction that reads, lowers, spends, or otherwise touches the sovereign machinery of a twin from outside it.

Why the language forbids it

Axiom III, at full strength. Spec §4.8 is explicit that budgets and thresholds are legal only inside the twin they govern, and that referencing another twin's attention block "is not a permission error at runtime; it is a parse-impossible construction." Spec §5 counts this among its two load-bearing absences: no production allows an attention or membrane block to name a foreign twin as its subject. The Osmosis Protocol spec §3 states the underlying law of the pressure engine:

The threshold is the receiver's property; no sender may lower it.

This is the founding inversion of the whole project. For fifty years already, the ambient economics of communication have subsidized free access to strangers' minds: anyone could place an item on your attention at no cost to themselves, and the entire defensive apparatus (filters, folders, do-not-disturb, inbox-zero rituals) lived on your side, at your expense, forever losing. Law I (Receiver Sovereignty) ends the subsidy, and O-006 is where the ending is enforced. Note how little it would take to undo this: a single construct that lets a sender adjust a receiver's threshold, one line of grammar, rebuilds the inbox. Every "priority" flag, every "urgent" subject line, every notification a sender could force through was exactly that construct in the old world. The language refuses to contain it.

How to fix

You cannot, and that is the point. There is no rewrite of a foreign-sovereignty reference that preserves its intent, because the intent, reaching past someone's declared bar, is exactly the thing being forbidden.

What you can do instead, all of it on your own side of the membrane: declare better holds, so that when their gaps form, your supply is the relevant match; earn trust over time, since a receiver who bonds you moves you to a friendlier sender class with a lower threshold (their choice, made in their source); or stake reputation on genuinely valuable unsolicited knowledge. The receiver's bar stays theirs in every case.

In v0.1

Structurally unwritable: the reference interpreter's parser only ever attaches membrane and attention blocks to the enclosing twin, and no parsed form can name another twin's blocks. As with O-001, the explicit AST-level guard is dissertation Ch. 2 stage 3 work (the sovereignty checker in the Rust semantic analyzer), defending against trees constructed by tools rather than typed by hands.

The formal counterpart is open. Theorem 3 (Attention soundness), which states that interrupt placements at a twin never exceed its declared budgets for any behavior of any other twin, is the machine-checked version of "this is the entire point," and it has not been proven yet. See The Open Ledger.