feat: GSTACK_* env-key shim for Conductor workspaces

New lib/conductor-env-shim.ts promotes GSTACK_ANTHROPIC_API_KEY and
GSTACK_OPENAI_API_KEY to canonical names when canonical is empty. Wired
into the four TS entry points that hit paid APIs or gbrain embeddings:
gstack-gbrain-sync.ts, gstack-model-benchmark, preflight-agent-sdk.ts,
test/helpers/e2e-helpers.ts. Side-effect-only import, 15 lines total.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

bin/gstack-gbrain-sync.ts

@@ -35,6 +35,7 @@ import { execSync, spawnSync } from "child_process";
 import { homedir } from "os";
 import { createHash } from "crypto";
 
+import "../lib/conductor-env-shim";
 import { detectEngineTier, withErrorContext, canonicalizeRemote } from "../lib/gstack-memory-helpers";
 import { ensureSourceRegistered, sourcePageCount } from "../lib/gbrain-sources";
 import { localEngineStatus, type LocalEngineStatus } from "../lib/gbrain-local-status";

bin/gstack-model-benchmark

@@ -24,6 +24,7 @@
  *   gstack-model-benchmark --prompt "hi" --models claude,gpt,gemini --dry-run
  */
 
+import '../lib/conductor-env-shim';
 import * as fs from 'fs';
 import * as path from 'path';
 import { runBenchmark, formatTable, formatJson, formatMarkdown, type BenchmarkInput } from '../test/helpers/benchmark-runner';

lib/conductor-env-shim.ts

@@ -0,0 +1,14 @@
+/**
+ * Conductor workspaces don't inherit the user's interactive shell env, so the
+ * canonical ANTHROPIC_API_KEY / OPENAI_API_KEY may be missing while
+ * Conductor's GSTACK_-prefixed forms are present. Promote the GSTACK_ form to
+ * canonical when canonical is empty, so subprocesses (gbrain embed,
+ * @anthropic-ai/claude-agent-sdk, etc) pick it up.
+ *
+ * Import this for its side effect: `import "../lib/conductor-env-shim";`
+ */
+for (const key of ["ANTHROPIC_API_KEY", "OPENAI_API_KEY"] as const) {
+  if (!process.env[key] && process.env[`GSTACK_${key}`]) {
+    process.env[key] = process.env[`GSTACK_${key}`];
+  }
+}

scripts/preflight-agent-sdk.ts

@@ -16,6 +16,7 @@
  * side effects beyond stdout and a ~15 token API call.
  */
 
+import '../lib/conductor-env-shim';
 import { query, type SDKMessage } from '@anthropic-ai/claude-agent-sdk';
 import { readOverlay } from './resolvers/model-overlay';
 import { resolveClaudeBinary } from '../browse/src/claude-bin';

test/helpers/e2e-helpers.ts

@@ -5,6 +5,7 @@
  * tests across multiple files by category.
  */
 
+import '../../lib/conductor-env-shim';
 import { describe, test, beforeAll, afterAll, expect } from 'bun:test';
 import type { SkillTestResult } from './session-runner';
 import { EvalCollector, judgePassed } from './eval-store';