What causes a CI cache that grows until it slows builds or fills quota?

Every build writes a new cache entry but nothing prunes old ones, so the cache store fills with stale keys and eventually evicts useful entries or hits quota.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Stop Your CI Cache From Growing Unbounded

Quick answer: Use stable, content-derived cache keys with restore fallbacks, scope caches per branch, and prune old entries on a schedule to keep the store lean.

An ever-growing cache eventually costs you more than it saves. Disciplined keys and pruning keep it healthy. Here is how.

How to fix it

1. Use content-derived keys

Key caches on lockfile or asset hashes so identical inputs reuse one entry instead of creating a new one each run.

2. Scope and limit

Namespace caches per branch and rely on restore-keys so feature branches do not each leave a permanent full-size cache.

3. Prune on a schedule

Run a periodic job that deletes cache entries older than a retention window to reclaim space.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

The errors you never hear about are the ones quietly costing you players. Visibility turns them into a worklist.