Avoid re-uploading existing Go cache entries

[jacobwgillespie]

Note

Medium Risk
Changes when cache entries are uploaded remotely; incorrect wrote detection could skip needed uploads, though behavior is covered by new tests.

Overview
Disk cache puts now return whether bytes were actually written. When the object and action index already exist at the expected size, the local put is a no-op and reports no write.

Remote uploads are skipped on those no-op puts (and when outputID is empty), so repeat Put calls for the same entry no longer spawn background HTTP PUTs to Depot. Parent directories are created with MkdirAll before writing cache files.

Handler metrics for get/put were adjusted so deferred error/hit/miss accounting still runs via an explicit retErr instead of named return parameters. Tests cover “second put does not hit remote” and the disk wrote flag.

^{Reviewed by Cursor Bugbot for commit f51083f. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Named return wrote shadowed by different-typed local variable
  • Renamed the local byte count from writeAtomic to bytesWritten so it no longer shadows the named boolean return value.

Or push these changes by commenting:

@cursor push 6b4e26b361

Preview (6b4e26b361)

diff --git a/pkg/cmd/gocache/gocache.go b/pkg/cmd/gocache/gocache.go
--- a/pkg/cmd/gocache/gocache.go
+++ b/pkg/cmd/gocache/gocache.go
@@ -613,12 +613,12 @@
 		}
 		zf.Close()
 	} else {
-		wrote, err := writeAtomic(file, body)
+		bytesWritten, err := writeAtomic(file, body)
 		if err != nil {
 			return "", false, fmt.Errorf("unable to write to disk: %w", err)
 		}
-		if wrote != size {
-			return "", false, fmt.Errorf("wrote %d bytes, expected %d", wrote, size)
+		if bytesWritten != size {
+			return "", false, fmt.Errorf("wrote %d bytes, expected %d", bytesWritten, size)
 		}
 	}

_{You can send follow-ups to the cloud agent here.}

^{Reviewed by Cursor Bugbot for commit dd3a563. Configure here.}