fix(core): Create the cache dir before writing app-start config (JAVA-613)

The removed init-time mkdirs() ran on the dsn-hashed cache path and created
the un-hashed parent as a side effect. handleAppStartProfilingConfig writes
app_start_profiling_config into that parent via createNewFile(), which fails
with IOException when the parent is missing, and the surrounding catch
swallows it into a log line. The next launch then finds no config and cannot
start app-start profiling.

This was masked because the profiling traces dir still calls mkdirs() on
<cacheDir>/<dsnHash>/profiling_traces, creating the un-hashed grandparent --
but only when profiling is enabled, which every existing test did. The new
test leaves profiling off so nothing else materializes the dir.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: runningcode

sentry/src/main/java/io/sentry/Sentry.java

@@ -24,6 +24,7 @@
 import io.sentry.util.DebugMetaPropertiesApplier;
 import io.sentry.util.FileUtils;
 import io.sentry.util.InitUtil;
+import io.sentry.util.LazyDirectory;
 import io.sentry.util.LoadClass;
 import io.sentry.util.Platform;
 import io.sentry.util.SentryRandom;
@@ -463,8 +464,9 @@ private static void handleAppStartProfilingConfig(
           () -> {
             final String cacheDirPath = options.getCacheDirPathWithoutDsn();
             if (cacheDirPath != null) {
+              final @NotNull LazyDirectory cacheDir = new LazyDirectory(cacheDirPath);
               final @NotNull File appStartProfilingConfigFile =
-                  new File(cacheDirPath, APP_START_PROFILING_CONFIG_FILE_NAME);
+                  new File(cacheDir.getFile(), APP_START_PROFILING_CONFIG_FILE_NAME);
               try {
                 // We always delete the config file for app start profiling
                 FileUtils.deleteRecursively(appStartProfilingConfigFile);
@@ -481,6 +483,9 @@ private static void handleAppStartProfilingConfig(
                           "Tracing is disabled and app start profiling will not start.");
                   return;
                 }
+                // The cache dir is no longer created during init, so materialize it here before
+                // writing: createNewFile() fails if the parent is missing.
+                cacheDir.getOrCreate();
                 if (appStartProfilingConfigFile.createNewFile()) {
                   // If old app start profiling is false, it means the transaction will not be
                   // sampled, but we create the file anyway to allow continuous profiling on app

sentry/src/test/java/io/sentry/SentryTest.kt

@@ -1316,6 +1316,23 @@ class SentryTest {
     assertTrue(appStartProfilingConfigFile.exists())
   }
 
+  @Test
+  fun `init creates app start profiling config when the cache dir does not exist yet`() {
+    val path = getTempPath()
+    // Profiling is left disabled on purpose: it is the only other init-time consumer that creates
+    // the cache dir, so with it off nothing materializes the dir before the config is written.
+    initForTest {
+      it.dsn = dsn
+      it.cacheDirPath = path
+      it.isEnableAppStartProfiling = false
+      it.isStartProfilerOnAppStart = true
+      it.tracesSampleRate = 0.0
+      it.profilesSampleRate = null
+      it.executorService = ImmediateExecutorService()
+    }
+    assertTrue(File(path, "app_start_profiling_config").exists())
+  }
+
   @Test
   fun `init saves SentryAppStartProfilingOptions to disk`() {
     var options = SentryOptions()