Your custom task uses @InputFiles for a jar classpath, and the build cache never hits across CI agents. Walk through diagnosing and fixing the input normalization.

## Step 1 — Reproduce and observe Enable cache diagnostics: run with `--build-cache -Dorg.gradle.caching.debug=true` or publish a build scan with `--scan`. The output shows each task's individual input property fingerprints and the resulting cache key. Compare the same task across two agents: you'll see the classpath property's hash differs even though the dependencies are identical. ## Step 2 — Identify the root cause Two failure modes typically combine: 1. **Wrong normalization.** A property declared `@InputFiles` (without classpath annotation) defaults to `ABSOLUTE` path sensitivity. Agent A resolves jars under `/agentA/caches/...`, agent B under `/agentB/...`; the absolute paths differ, so the fingerprint differs and the cache never matches. 2. **Non-reproducible jar content.** Even with paths normalized, jars built with embedded timestamps or unstable entry order hash differently per build, busting the fingerprint. ## Step 3 — Apply classpath semantics Replace the generic annotation with a classpath-aware one: ```kotlin abstract class LaunchTask : DefaultTask() { // BEFORE: order/path/byte sensitive, defaults to ABSOLUTE // @get:InputFiles abstract val classpath: ConfigurableFileCollection // AFTER: path-insensitive, jar-normalized runtime classpath @get:Classpath abstract val classpath: ConfigurableFileCollection } ``` `@Classpath` ignores the absolute location of jars and normalizes their internal entries, so two agents resolving the same dependencies fingerprint equally. If the classpath feeds a compiler, use `@CompileClasspath` instead to additionally collapse non-ABI changes. ## Step 4 — Make jars reproducible For archives you produce, ensure deterministic content so even content hashing is stable: ```kotlin tasks.withType<AbstractArchiveTask>().configureEach { isPreserveFileTimestamps = false isReproducibleFileOrder = true } ``` ## Step 5 — Prevent regression at scale This is a governance problem, not a one-off. Put the classpath annotation in your **convention plugin's** task types, and rely on Gradle's task validation (which warns when a cacheable task's file input lacks proper normalization) plus a CI check that no custom classpath input is declared as plain `@InputFiles`. Track shared-cache hit rate as a metric; a sudden drop usually means a new task shipped with the wrong normalization. ## Summary The portability of a classpath input is governed by its declared normalization. Generic `@InputFiles` is ABSOLUTE and byte-exact; `@Classpath`/`@CompileClasspath` are path-insensitive and jar/ABI-normalized. Choosing the right annotation — and keeping archives reproducible — is what makes a remote cache actually shared across agents.