[ASWB] [Android] Kotlin source files in src/main/kotlin are not recognized as a source root

[phoenixwxy]

Description of the bug:

Bug Description
The Android Studio Bazel Plugin (ASWB) does not correctly identify src/main/kotlin as a source directory when it is used alongside a separate src/main/java directory within the same Bazel target.

While the project builds successfully using Bazel (from the command line or the IDE's "Build" button), the IDE itself fails to index the Kotlin files correctly. This leads to:

Failed Symbol Resolution: Code in .kt files is highlighted in red, with errors like "Unresolved reference".
No Code Completion: Standard IDE features for Kotlin do not work.
Broken Navigation: "Go to Declaration," "Find Usages," and other navigation features do not work for symbols defined in the kotlin/ directory.
The expected behavior is for the IDE to recognize both src/main/java and src/main/kotlin as source roots, enabling full IDE support for both Java and Kotlin files in the project, which is standard behavior in Gradle-based Android projects.

Steps to Reproduce
1.Create an Android project with the following directory structure, separating Java and Kotlin sources:

my_android_app/
└── src
    └── main
        ├── AndroidManifest.xml
        ├── BUILD.bazel
        ├── java/com/my/package/MyJavaClass.java
        └── kotlin/com/my/package/MyKotlinActivity.kt

2.In BUILD.bazel, define an android_binary or android_library target that includes both source directories in its srcs attribute, for example: srcs = glob(["java//*.java", "kotlin//*.kt"]).
3.Import the project into Android Studio using the Bazel plugin ("Import Bazel Project").
4.After the sync completes, open the MyKotlinActivity.kt file.
5.Observe that the IDE cannot resolve symbols, even basic ones like AppCompatActivity.
Minimal, Reproducible BUILD.bazel Example
Here is a sample BUILD.bazel file that demonstrates the issue:

# //apps/Android/bazel_demo/src/main/BUILD.bazel
load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_android_library")
# This library will contain the Kotlin code
kt_android_library(
    name = "lib_kt",
    srcs = glob(["kotlin/**/*.kt"]),
    custom_package = "com.phoenix.bazel_demo",
    manifest = "AndroidManifest.xml",
    resource_files = glob(["res/**"]),
    deps = [
        # Common Android dependencies
    ],
)
# A final binary that depends on the Kotlin library
# (A single android_binary with mixed sources also shows the issue)
android_binary(
    name = "app",
    srcs = glob(["java/**/*.java"]), # Assuming MainActivity is Java
    custom_package = "com.phoenix.bazel_demo",
    manifest = "AndroidManifest.xml",
    deps = [
        ":lib_kt",
    ],
)

Version Information
Android Studio Version:

Android Studio Otter 2 Feature Drop | 2025.2.2
Build #AI-252.27397.103.2522.14514259, built on December 1, 2025
Runtime version: 21.0.8+-14196175-b1038.72 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Linux 6.12.43+deb13-amd64
Current Desktop: GNOME

Android Studio Bazel Plugin Version: com.google.idea.bazel.aswb (14514259)

Bazel version: bazel 8.4.2
rules_android version:0.6.6
rules_kotlin version:2.2.0

Which category does this issue belong to?

Android

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

No response

Which operating system are you running Bazel on?

Linux User 6.12.43+deb13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.43-1 (2025-08-27) x86_64 GNU/Linux

What is the output of bazel info release?

release 8.4.2

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse HEAD ?

If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

No response

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response

[jagobagascon]

I'm having a similar issue. Not sure if its related but instead of highlighting my Kotlin code in red, Android Studio simply ignores it.

Code analysis is disabled for Kotlin files

and if I try to enable it I get this error:

[...]
INFO: Build completed successfully, 2 total actions
[...]
Fetched and parsed artifact info files in 14 ms
Fetching 0 new artifacts (0.00 MB) out of 201 requested...
Downloading done.
Building dependencies failed
  because: java.lang.IllegalArgumentException

Java code works perfectly fine.

[dongheekim23]

I've been having this issue as well and it seems like it's due to not specifying "kt_android_library" and "kt_android_local_test" as an Android rule in RuleKinds class. Adding the rule name to the set lets the IDE mark Kotlin/Java source folders correctly as source roots and enables go to declaration functionality, but like @jagobagascon mentioned above, syntax highlighting is disabled on both Kotlin and Java files (I'm using Android Studio Otter 3 2025.2.3 version which is the latest). It seems like at the end of query sync via Bazel sync, syntax highlighting gets disabled when it is enabled before the sync takes place.

Seems like updating the QuerySyncLanguage.JVM's DependencyTrackingBehavior from EXTERNAL_DEPENDENCIES to SELF just like QuerySyncLanguage.CC, then syntax highlighting works again, although 3rd-party dependencies from Maven repo, etc. don't get highlighted automatically. For the syntax highlighting, I didn't realize that you have to click on "build dependencies" explicitly to trigger downloading of external dependencies + enable syntax highlighting through code analysis in case there are missing dependencies, unlike C/C++ code (since their dependency tracker behavior is set to SELF, meaning no external dependencies are needed to be downloaded for code analysis). So adding the rule names will resolve the syntax highlighting issue as well.