Tracking: encrypted JSON documents (json_tree) in the Go SDK #1347

Background

json_tree is the EQL v4 type family for an encrypted JSON document. EQL (Encrypt Query Language) is the SQL library installed into a customer's PostgreSQL database. The family supports:

• containment (@>, <@);
• equality at a path;
• ordering and ranges at declared paths;
• -> extraction;
• subtree walks.

The Rust engine and the SQL are built in #1288, #1325, #1329 and #1336, with a property test in #1345.

Problem

None of this is usable from Go. The Go SDK reaches the engine only through a data plan (ADR-0007), and the engine refuses the JSON index there. The family is also missing from the EQL catalog, so no Go types are generated for it.

Proposal

The plan is docs/plans/2026-10-24-go-json-tree.md (#1353). It has five steps, one PR each. Steps 1-3 are Rust and unblock Go.

Sub-issues are listed below, in order.

Decisions are needed before step 4. The plan recommends an answer to each:

1. The Go types a field may have.
2. Crossing the guest boundary as JSON text.
3. The type of a containment needle.
4. Generated accessors for ordered paths.
5. The scope of the first release.