fix: refuse a result nested inside another type

[arcjet-rei]

gravity represents a result with Go's multiple return values (T, error, or error alone), which only a function's results can carry. A result in a record field, a variant case payload, a list element, an option payload or another result's ok type was written out anyway: gravity exited 0, and the Go failed to compile (R uint32, error as a struct field). gravity now refuses these at generation time with a message naming the position, as it already does for the result shapes it cannot generate.

A result in a function's own result is unaffected. Supporting nested results needs a decision on their Go type, which this change does not make.

🤖 Generated with Claude Code

[arcjet-review]

Arcjet Review — 🟢 Low Risk

Decision: Checked

Rationale: The PR makes a small, well-scoped code generation validation change to reject nested WIT result types before emitting invalid Go. The behavior is covered by targeted unit tests for record fields, variant payloads, list elements, option payloads, nested result ok types, and the still-supported top-level function result case. No escalation triggers fired, and the security review found no auth, injection, secrets, cryptography, or OWASP concerns.

Summary of Changes

Adds resolve_nested_type to refuse result types embedded inside other types, updates import analysis and compound type resolution to use it, and adds regression tests for rejected nested result positions while preserving top-level function result support.

Notes

The AI assessed this PR as approvable, but the trust level (1) does not allow auto-approval. A human reviewer must approve this PR.

_{Review: 0669fdd2 | Model: openai/gpt-5.5 | Powered by Arcjet Review}