Why Signed State

The core distinction is:

• a signed message proves "I said this"
• a signed state proves "this fact was part of my committed state"

That difference matters when a protocol needs more than one-off authorship.

What Signed State Adds

Signed state gives you:

• membership: this fact was in my set
• absence: this fact was not in my set
• history: this was true under root R at a given time or version
• selective disclosure: I can reveal one slice without revealing everything
• amortization: one root authenticates many facts
• composition: verified facts can be used to derive higher-order facts

When It Matters

Signed state is worth the cost when:

• more than one peer contributes facts to the outcome
• facts evolve over time
• old states still matter
• verifiers usually need only a subset of the total state
• disputes or audits are likely

When It Does Not

Signed state is usually not worth it when:

• one signed document is enough
• one authority owns almost all relevant truth
• full disclosure is acceptable
• the protocol has no real historical or dispute pressure

Practical Test

A protocol is a strong candidate when it is:

• multi-peer
• stateful
• partial

If one of those is missing, plain signatures may be enough.