feat(sdk/go): Go SDK PR decomposition plan

[rhuss]

Go SDK PR Decomposition Plan

The Go SDK contribution (#2044) is feature-complete but too large for practical review in its current 3-PR form. This tracking issue describes the decomposition into 6 smaller, independently reviewable PRs.

Motivation

The Go SDK contribution totals ~50K lines across ~500 files. In its current 3-PR form, PR #2225 alone is ~38K lines (117 files), which is too large for a single review sitting. In the contributor meeting on 2026-07-14, we discussed decomposing the PRs to make them more approachable for reviewers.

Strategy

Hybrid foundation + vertical slices. The first PR is intentionally larger because it carries the shared foundation (module setup, all types, interfaces, auth, gRPC infrastructure) plus the sandbox client as the first fully working vertical. After that first merge, the SDK is usable end-to-end for sandbox management. Each subsequent PR then incrementally adds one more resource group, and after every merge the SDK is fully working with an expanded API surface.

Each PR includes a structured "How to Review" section with review zones (must-review, pattern-review, skim).

PR Checklist

• PR A: Foundation + types + sandbox (~4.6K code + ~8.5K tests, 79 files) - feat(sdk/go): add Go SDK foundation, types, and sandbox client (A) #2271
  Module setup, all domain types, full ClientInterface, shared infrastructure (errors, auth, gRPC), sandbox client + converter + tests.
  After merge: consumers can go get the module and create/manage sandboxes.

• PR B: Exec + file + health (~1.2K code + ~1.8K tests, 18 files)
  Command execution, file transfer, health checks. Interfaces, clients, converters, tests.
  After merge: consumers can run commands and transfer files.

• PR C: Provider + profile + config + refresh (~2.2K code + ~3.3K tests, 26 files)
  Provider management and credential lifecycle. Interfaces, clients, converters, tests.
  After merge: consumers can manage AI providers and credentials.

• PR D: Policy + service + TCP + SSH (~2.6K code + ~3.9K tests, 22 files)
  Network policy, service exposure, tunneling. Interfaces, clients, converters, tests.
  After merge: consumers can manage network policies and expose services.

• PR E: Gateway + OIDC + edge + fakes (~12K lines, 70 files)
  Gateway auto-discovery, OIDC authentication flows, edge client, in-memory test fakes.
  After merge: consumers can auto-discover gateways, authenticate via OIDC, and write tests with fakes.

• PR F: Docs + CI (~0.5K lines, 7 files)
  4 MDX documentation pages, CI job, mise tasks, SDK navigation.
  After merge: SDK is documented and CI-tested.

Review Guide

Each PR description will include:

• Review zones: files categorized as must-review, pattern-review, or skim
• Pattern exemplars: one test file per pattern to review carefully, spot-check others
• Key design decisions: what was decided and why

Supersedes

This plan supersedes the current 3-PR split:

• feat(sdk/go): add Go SDK foundation and core clients (1/3) #2225 (1/3) will be closed and replaced by PRs A-D
• feat(sdk/go): add gateway client, auth, and fakes (2/3) #2226 (2/3) will be closed and replaced by PR E
• docs(sdk/go): add documentation and CI job (3/3) #2227 (3/3) will be closed and replaced by PR F