diff --git a/sdk/src/query-gsd-tools-runtime.ts b/sdk/src/query-gsd-tools-runtime.ts
index 1db59bc82..d58b38e3f 100644
--- a/sdk/src/query-gsd-tools-runtime.ts
+++ b/sdk/src/query-gsd-tools-runtime.ts
@@ -7,7 +7,7 @@ import { QuerySubprocessAdapter } from './query-subprocess-adapter.js';
 import { QueryNativeDirectAdapter } from './query-native-direct-adapter.js';
 import { QueryNativeHotpathAdapter } from './query-native-hotpath-adapter.js';
 import { formatQueryRawOutput } from './query-raw-output-projection.js';
-import { GSDToolsError } from './gsd-tools-error.js';
+import { failureToolsError, timeoutToolsError } from './query-tools-error-factory.js';
 
 export interface GSDToolsRuntime {
   registry: ReturnType<typeof createRegistry>;
@@ -34,18 +34,18 @@ export function createGSDToolsRuntime(opts: {
     timeoutMs: opts.timeoutMs,
     workstream: opts.workstream,
     createTimeoutError: (message, command, args, stderr, timeoutMs) =>
-      GSDToolsError.timeout(message, command, args, stderr, timeoutMs),
+      timeoutToolsError(message, command, args, stderr, timeoutMs),
     createFailureError: (message, command, args, exitCode, stderr) =>
-      GSDToolsError.failure(message, command, args, exitCode, stderr),
+      failureToolsError(message, command, args, exitCode, stderr),
   });
 
   const nativeDirectAdapter = new QueryNativeDirectAdapter({
     timeoutMs: opts.timeoutMs,
     dispatch: (registryCommand, registryArgs) => registry.dispatch(registryCommand, registryArgs, opts.projectDir),
     createTimeoutError: (message, command, args) =>
-      GSDToolsError.timeout(message, command, args, '', opts.timeoutMs),
+      timeoutToolsError(message, command, args, '', opts.timeoutMs),
     createFailureError: (message, command, args, cause) =>
-      GSDToolsError.failure(message, command, args, 1, '', { cause }),
+      failureToolsError(message, command, args, 1, '', cause),
   });
 
   const transport = new GSDTransport(registry, {
diff --git a/sdk/src/query-tools-error-factory.test.ts b/sdk/src/query-tools-error-factory.test.ts
new file mode 100644
index 000000000..dad1075e6
--- /dev/null
+++ b/sdk/src/query-tools-error-factory.test.ts
@@ -0,0 +1,25 @@
+import { describe, expect, it } from 'vitest';
+import { ErrorClassification, GSDError } from './errors.js';
+import {
+  failureToolsError,
+  timeoutToolsError,
+  toToolsErrorFromUnknown,
+} from './query-tools-error-factory.js';
+
+describe('query tools error factory', () => {
+  it('builds timeout and failure tools errors', () => {
+    expect(timeoutToolsError('t', 'state', ['load'], '', 10).classification).toEqual({ kind: 'timeout', timeoutMs: 10 });
+    expect(failureToolsError('f', 'state', ['load'], 1).classification).toEqual({ kind: 'failure' });
+  });
+
+  it('maps GSDError to failure with semantic exit code', () => {
+    const err = toToolsErrorFromUnknown('state', ['load'], new GSDError('bad', ErrorClassification.Validation));
+    expect(err.exitCode).toBe(10);
+    expect(err.classification).toEqual({ kind: 'failure' });
+  });
+
+  it('maps timeout-like unknown errors to timeout classification', () => {
+    const err = toToolsErrorFromUnknown('state', ['load'], new Error('gsd-tools timed out after 50ms: state load'));
+    expect(err.classification).toEqual({ kind: 'timeout', timeoutMs: 50 });
+  });
+});
diff --git a/sdk/src/query-tools-error-factory.ts b/sdk/src/query-tools-error-factory.ts
new file mode 100644
index 000000000..838f51381
--- /dev/null
+++ b/sdk/src/query-tools-error-factory.ts
@@ -0,0 +1,31 @@
+import { GSDError, exitCodeFor } from './errors.js';
+import { GSDToolsError } from './gsd-tools-error.js';
+import { errorMessage, toFailureSignal } from './query-failure-classification.js';
+
+export function timeoutToolsError(message: string, command: string, args: string[], stderr = '', timeoutMs?: number): GSDToolsError {
+  return GSDToolsError.timeout(message, command, args, stderr, timeoutMs);
+}
+
+export function failureToolsError(
+  message: string,
+  command: string,
+  args: string[],
+  exitCode: number | null,
+  stderr = '',
+  cause?: unknown,
+): GSDToolsError {
+  return GSDToolsError.failure(message, command, args, exitCode, stderr, cause === undefined ? undefined : { cause });
+}
+
+export function toToolsErrorFromUnknown(command: string, args: string[], err: unknown): GSDToolsError {
+  if (err instanceof GSDError) {
+    return failureToolsError(err.message, command, args, exitCodeFor(err.classification), '', err);
+  }
+
+  const msg = errorMessage(err);
+  const signal = toFailureSignal(err);
+  if (signal.kind === 'timeout') {
+    return timeoutToolsError(msg, command, args, '', signal.timeoutMs);
+  }
+  return failureToolsError(msg, command, args, 1, '', err instanceof Error ? err : undefined);
+}
diff --git a/sdk/src/query-tools-error-mapper.ts b/sdk/src/query-tools-error-mapper.ts
index 06f54b6eb..835545b6e 100644
--- a/sdk/src/query-tools-error-mapper.ts
+++ b/sdk/src/query-tools-error-mapper.ts
@@ -1,27 +1,9 @@
-import { GSDError, exitCodeFor } from './errors.js';
-import { GSDToolsError } from './gsd-tools-error.js';
-import { errorMessage, toFailureSignal } from './query-failure-classification.js';
+import { toToolsErrorFromUnknown } from './query-tools-error-factory.js';
+import type { GSDToolsError } from './gsd-tools-error.js';
 
 /**
  * Module owning projection of internal errors to GSDToolsError contract.
  */
 export function toGSDToolsError(command: string, args: string[], err: unknown): GSDToolsError {
-  if (err instanceof GSDError) {
-    return GSDToolsError.failure(
-      err.message,
-      command,
-      args,
-      exitCodeFor(err.classification),
-      '',
-      { cause: err },
-    );
-  }
-
-  const msg = errorMessage(err);
-  const signal = toFailureSignal(err);
-  if (signal.kind === 'timeout') {
-    return GSDToolsError.timeout(msg, command, args, '', signal.timeoutMs, err instanceof Error ? { cause: err } : undefined);
-  }
-
-  return GSDToolsError.failure(msg, command, args, 1, '', err instanceof Error ? { cause: err } : undefined);
+  return toToolsErrorFromUnknown(command, args, err);
 }