* fix(#2832): gsd-sdk auto detects Codex runtime correctly
Two-part fix for #2832 (gsd-sdk auto silently routing non-Claude runtime
projects through the Claude Agent SDK):
1. Runtime gate at the `auto` entry point. New `runtime-gate.ts` exports
`assertRuntimeSupportsAutoMode(config)` which throws an actionable error
when `GSD_RUNTIME` / `config.runtime` resolves to a non-Claude runtime
(codex, gemini, opencode, etc.). The autonomous orchestrator only knows
how to drive `@anthropic-ai/claude-agent-sdk` today; failing fast with a
clear pointer at the in-session slash commands beats the previous instant
`[FAILED] $0.00 0.1s` flake. Wired into `cli.ts` before the GSD/InitRunner
construction.
2. Runtime-aware `resolveModel()` in `session-runner.ts`. The profile -> id
map (`balanced -> claude-sonnet-4-6`, etc.) was applied unconditionally,
so even with `runtime: codex` and `resolve_model_ids: omit` the SDK
forced a Claude id into `query()`. Now the profile map only fires when
the runtime is Claude and the explicit `resolve_model_ids: "omit"` knob
short-circuits to undefined, mirroring `query/config-query.ts`.
Tests (vitest, sdk/src):
- runtime-gate.test.ts (8 cases): claude / unset / unknown pass; codex,
gemini, opencode throw; GSD_RUNTIME wins over config.runtime; error
message references #2832 and the slash-command workaround.
- session-runner.test.ts (4 new cases under "resolveModel runtime
awareness (#2832)"): codex runtime + balanced profile -> no model
injected; resolve_model_ids: omit -> no model; claude runtime still
resolves to claude-sonnet-4-6 (no regression); explicit options.model
wins on any runtime.
* fix(#2832): address CR — env-precedence in resolveModel + accurate source attribution
Two CodeRabbit findings on PR #2844:
1. session-runner.ts:resolveModel() (Major) — read runtime via detectRuntime()
so GSD_RUNTIME env precedence is honored. Without this, a Codex run with
a Claude-shaped config still fell into the Claude-only profile-id branch.
2. runtime-gate.ts:assertRuntimeSupportsAutoMode() (Minor) — when GSD_RUNTIME
holds an unsupported value, detectRuntime() falls through to config but
the source label still reported the discarded env value. Fix: validate
env against SUPPORTED_RUNTIMES before attributing the source.
Tests added for both: env-precedence in session-runner, source attribution
in runtime-gate. 17/17 pass.
