Amend ADR-0007 for operator queries, and add the guest's query, verify and target_limit exports #1188

Background

ADR-0007 says a binding reaches the engine through a plan lowered from data. ADR-0009 makes the operator, not the index, the thing a query names, and gives probabilistic terms verify and target_limit. ADR-0009's appendix B sketches what then crosses the binding.

Problem

The data grammar a binding lowers names a field and, for a query, picks the term by the field's EQL type. It has no operator and no operator input, and no export can verify a decrypted value or size a fetch. Without them the Go SDK cannot offer per-operator queries, and a language SDK would have to reimplement the tokenizer to verify, which is the "lives twice" cost ADR-0007 accepts only for an encoder.

Proposal

• Amend ADR-0007 with the query side, after ADR-0009 is accepted: the operator and its input in the data grammar, the term and its query domain back, and verify and target_limit as engine exports.
• A guest export that derives a query term from a plan, a field, an operator name and its input. It refuses an operator the field's type does not answer, with the same shape of error as a mistyped field.
• A batched verify export: one term and a page of decrypted values in, one boolean per value out.
• A target_limit export: a term, want and the statistics in, the limit out.
• The engine catalog reports, per EQL type, the operators it answers and the fidelity of each, so a generator can ask before the program runs.
• Tests on the Rust side, and Go tests through the guest that hold the exports to the Rust results.

Related

• Depends on stack-encrypt: name the operator, not the index, in a query (Eq and Matches) #1182, stack-encrypt: verify a Matches query's rows after decrypt (Probabilistic) #1183 and stack-encrypt: size a probabilistic query's fetch with target_limit and Stats #1184.
• Go SDK: generate one query method per operator, with Verify and TargetLimit on probabilistic terms #1189: the Go SDK methods built on these exports.
• docs(adr): ADR-0009, operators select the index and a query term is not the stored term #1177: ADR-0009, appendix B.
• Tracking: implement ADR-0009, operator-typed query terms for Stack Encrypt #1178: tracks ADR-0009.