Ren'Py build.classify rules for dynamically loaded assets that vanish in production builds

Resolving Missing Dynamic Assets

To ensure dynamically loaded assets are included in your production build, you must define a build.classify rule using a regular expression that matches the entire directory path. Because Ren'Py's static analysis cannot detect strings built at runtime, any file not explicitly matched by a classification rule is excluded from the .rpa archives.

Forcing Directory Classification

You can force the inclusion of an entire folder by using a regex pattern in options.rpy. This ensures that every file within that path is packaged, regardless of whether it is referenced in a script.

# Include everything in the 'game/images/dynamic/' folder into the 'images' archive
build.classify('game/images/dynamic/.*', 'images')

# If your assets are in a top-level folder like 'game/audio/music/'
build.classify('game/audio/music/.*', 'audio')

Case Sensitivity and Validation

Ren'Py does not currently provide a build-time "strict mode" to fail the build when assets are unclassified or when filename casing is mismatched. The Check Script (Lint) tool primarily validates static references and will not catch errors in dynamically constructed paths.

• The Risk: A path like "Images/bg.png" works on Windows/macOS (case-insensitive) but will fail on Linux or Android (case-sensitive) once packed into an archive.
• The Solution: You must implement an external naming convention check or a custom Python script to verify that your dynamic string builders match the actual on-disk casing exactly.

Archiving vs. Loose Files

While omitting a file from all build.classify rules keeps it as a loose file in the distribution, this is not recommended for dynamic assets. Loose files are exposed to the user and are more prone to platform-specific path resolution errors. Classifying them into an .rpa archive is the supported approach for production stability.

Verification Steps

1. Archive Inspection: Use an RPA extractor tool on your distribution build to verify the dynamic assets actually exist inside the .rpa file.
2. Cross-Platform Testing: Run the packaged build on a Linux environment to identify case-sensitivity failures that were masked by the SDK on Windows/macOS.

Diagnostic Note: Are you using absolute paths or paths relative to the game/ directory in your renpy.file() calls? This determines whether your build.classify regex needs to start with 'game/' or the subfolder name.