diff --git a/src/services/test-runner.js b/src/services/test-runner.js
index 461c303..36384e4 100644
--- a/src/services/test-runner.js
+++ b/src/services/test-runner.js
@@ -24,6 +24,7 @@ import {
   runTests,
 } from '../test-runner/index.js';
 import * as output from '../utils/output.js';
+import { writeSession as defaultWriteSession } from '../utils/session.js';
 import { createBuildObject } from './build-manager.js';
 
 export class TestRunner extends EventEmitter {
@@ -46,6 +47,7 @@ export class TestRunner extends EventEmitter {
       getBuild,
       finalizeApiBuild,
       output,
+      writeSession: defaultWriteSession,
       createError: (message, code) => new VizzlyError(message, code),
     };
   }
@@ -94,7 +96,7 @@ export class TestRunner extends EventEmitter {
   }
 
   async createBuild(options, tdd) {
-    return createBuild({
+    let buildId = await createBuild({
       runOptions: options,
       tdd,
       config: this.config,
@@ -105,6 +107,18 @@ export class TestRunner extends EventEmitter {
         output: this.deps.output,
       },
     });
+
+    if (!tdd && buildId) {
+      let writeSession = this.deps.writeSession || defaultWriteSession;
+      writeSession({
+        buildId,
+        branch: options?.branch,
+        commit: options?.commit,
+        parallelId: options?.parallelId,
+      });
+    }
+
+    return buildId;
   }
 
   async finalizeBuild(buildId, isTddMode, success, executionTime) {
diff --git a/tests/commands/preview.test.js b/tests/commands/preview.test.js
index 1442294..f745029 100644
--- a/tests/commands/preview.test.js
+++ b/tests/commands/preview.test.js
@@ -7,6 +7,8 @@ import {
   previewCommand,
   validatePreviewOptions,
 } from '../../src/commands/preview.js';
+import { TestRunner } from '../../src/services/test-runner.js';
+import { readSession, writeSession } from '../../src/utils/session.js';
 
 /**
  * Create mock output object that tracks calls
@@ -225,6 +227,89 @@ describe('previewCommand', () => {
     assert.strictEqual(capturedBuildId, 'session-build-123');
   });
 
+  it('uses build ID written by testRunner.createBuild', async () => {
+    let output = createMockOutput();
+    let capturedBuildId = null;
+    let buildIdFromRunner = 'api-build-from-test-runner';
+    let branch = 'feature/storybook-session';
+
+    let testRunner = new TestRunner(
+      {
+        apiKey: 'test-token',
+        apiUrl: 'https://api.test',
+        comparison: {},
+      },
+      {},
+      {
+        deps: {
+          spawn: () => {
+            throw new Error('spawn should not be called in createBuild test');
+          },
+          createApiClient: () => ({}),
+          createApiBuild: async () => ({ id: buildIdFromRunner }),
+          getBuild: async () => ({ id: buildIdFromRunner }),
+          finalizeApiBuild: async () => {},
+          output: {
+            debug: () => {},
+          },
+          writeSession: session => {
+            writeSession(session, { cwd: testDir, env: {} });
+          },
+          createError: (message, code) => {
+            let error = new Error(message);
+            error.code = code;
+            return error;
+          },
+        },
+      }
+    );
+
+    await testRunner.createBuild(
+      {
+        buildName: 'Storybook Build',
+        branch,
+        commit: 'abc123def456',
+        parallelId: 'parallel-227',
+      },
+      false
+    );
+
+    await previewCommand(
+      distDir,
+      {},
+      {},
+      {
+        loadConfig: async () => ({
+          apiKey: 'test-token',
+          apiUrl: 'https://api.test',
+        }),
+        readSession: options =>
+          readSession({
+            ...options,
+            cwd: testDir,
+            env: {},
+          }),
+        detectBranch: async () => branch,
+        createApiClient: () => ({}),
+        getBuild: async () => ({ project: { isPublic: true } }),
+        uploadPreviewZip: async (_client, buildId) => {
+          capturedBuildId = buildId;
+          return {
+            previewUrl: 'https://preview.test',
+            uploaded: 3,
+            totalBytes: 1000,
+            newBytes: 800,
+            reusedBlobs: 0,
+          };
+        },
+        output,
+        exit: () => {},
+      }
+    );
+
+    assert.strictEqual(capturedBuildId, buildIdFromRunner);
+  });
+
   it('uses explicit build ID from options over session', async () => {
     let output = createMockOutput();
     let capturedBuildId = null;
diff --git a/tests/services/test-runner.test.js b/tests/services/test-runner.test.js
new file mode 100644
index 0000000..6d0bab7
--- /dev/null
+++ b/tests/services/test-runner.test.js
@@ -0,0 +1,88 @@
+import assert from 'node:assert';
+import { describe, it } from 'node:test';
+import { TestRunner } from '../../src/services/test-runner.js';
+
+function createDeps(overrides = {}) {
+  return {
+    spawn: () => {
+      throw new Error('spawn should not be called in createBuild tests');
+    },
+    createApiClient: () => ({}),
+    createApiBuild: async () => ({ id: 'api-build-123' }),
+    getBuild: async () => ({ id: 'api-build-123' }),
+    finalizeApiBuild: async () => {},
+    output: {
+      debug: () => {},
+    },
+    writeSession: () => {},
+    createError: (message, code) => {
+      let error = new Error(message);
+      error.code = code;
+      return error;
+    },
+    ...overrides,
+  };
+}
+
+describe('services/test-runner', () => {
+  describe('createBuild', () => {
+    it('writes session context for API builds', async () => {
+      let writtenSessions = [];
+      let deps = createDeps({
+        writeSession: session => {
+          writtenSessions.push(session);
+        },
+      });
+      let testRunner = new TestRunner(
+        {
+          apiKey: 'test-key',
+          apiUrl: 'https://api.vizzly.dev',
+          comparison: {},
+        },
+        {},
+        { deps }
+      );
+
+      let buildId = await testRunner.createBuild(
+        {
+          buildName: 'Storybook Build',
+          branch: 'feature/session',
+          commit: 'abc123def456',
+          parallelId: 'parallel-42',
+        },
+        false
+      );
+
+      assert.strictEqual(buildId, 'api-build-123');
+      assert.deepStrictEqual(writtenSessions, [
+        {
+          buildId: 'api-build-123',
+          branch: 'feature/session',
+          commit: 'abc123def456',
+          parallelId: 'parallel-42',
+        },
+      ]);
+    });
+
+    it('does not write session context for TDD builds', async () => {
+      let writeSessionCalled = false;
+      let deps = createDeps({
+        writeSession: () => {
+          writeSessionCalled = true;
+        },
+      });
+      let testRunner = new TestRunner({}, {}, { deps });
+
+      let buildId = await testRunner.createBuild(
+        {
+          buildName: 'TDD Build',
+          branch: 'main',
+        },
+        true
+      );
+
+      assert.ok(buildId.startsWith('build-'));
+      assert.strictEqual(writeSessionCalled, false);
+    });
+  });
+});