A sigil is the one place something QNTX does is defined: what it is for, what
goes in, what comes out and how it refuses.
The HTTP API and MCP are surfaces of a sigil, and A2A will be one. A sigil is
one endpoint and one tool, and every surface does the same thing and refuses
the same way.
A signum holds the sigils of one subject: watchers is a signum, and list,
create, read, update and delete are its sigils. To A2A a signum is a skill.
Their shape is proto and nothing else. What is not a shape, the function that
answers, lives in server/sigil.
Reach lines name sigils and signa, per surface where that matters. The const
table is the floor, lines in system govern at runtime, and a caller is shown
only what they reach.
A2A is ROOT's alone for the foreseeable future, and it is for the owner's own
agents first: an agent is a token, and what it says is written under its own
DID. The boundary to other systems is deferred, and it will be runtime lines
in the attestation DSL.
Some routes are not sigils: .well-known, the /auth ceremony, / and /health,
/g/, /s/, the sockets, /mcp.