diff --git a/bin/gstack-gbrain-sync.ts b/bin/gstack-gbrain-sync.ts
index 732ee430c..4fc658ac4 100644
--- a/bin/gstack-gbrain-sync.ts
+++ b/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";
diff --git a/bin/gstack-model-benchmark b/bin/gstack-model-benchmark
index 7c48c910b..34227652c 100755
--- a/bin/gstack-model-benchmark
+++ b/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';
diff --git a/lib/conductor-env-shim.ts b/lib/conductor-env-shim.ts
new file mode 100644
index 000000000..7056525ec
--- /dev/null
+++ b/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}`];
+  }
+}
diff --git a/scripts/preflight-agent-sdk.ts b/scripts/preflight-agent-sdk.ts
index 8a0bc5618..6b3e9ea7c 100644
--- a/scripts/preflight-agent-sdk.ts
+++ b/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';
diff --git a/test/helpers/e2e-helpers.ts b/test/helpers/e2e-helpers.ts
index e51baa3f7..32510f13a 100644
--- a/test/helpers/e2e-helpers.ts
+++ b/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';