Travis CI build caching limits with dynamic dependency updates

Cache Persistence and Dependency Rotation

Travis CI provides a cache key in the .travis.yml configuration to persist directories across builds, which is typically used for node_modules or vendor folders to optimize execution time.

When dependencies are updated frequently, relying on a static cache key can lead to stale artifacts being injected into new builds. While rotating the cache key manually is a known workaround, there is uncertainty regarding the optimal balance between cache hit rates and the risk of dependency drift in high-velocity environments.

• What are the documented limits for automatic cache invalidation when the underlying dependency manifest changes?
• Is there a mechanism to programmatically trigger a cache refresh without modifying the .travis.yml file?