A-1270 part 1: move zstash into agent repo

Author: zhming0

go.mod

@@ -31,7 +31,6 @@ require (
 	github.com/buildkite/interpolate v0.1.5
 	github.com/buildkite/roko v1.4.0
 	github.com/buildkite/shellwords v1.0.1
-	github.com/buildkite/zstash v0.8.0
 	github.com/creack/pty v1.1.24
 	github.com/denisbrodbeck/machineid v1.0.1
 	github.com/dustin/go-humanize v1.0.1
@@ -51,7 +50,9 @@ require (
 	github.com/prometheus/client_golang v1.23.2
 	github.com/puzpuzpuz/xsync/v2 v2.5.1
 	github.com/qri-io/jsonschema v0.2.1
+	github.com/stretchr/testify v1.11.1
 	github.com/urfave/cli v1.22.17
+	github.com/wolfeidau/quickzip v1.0.2
 	go.opentelemetry.io/contrib/propagators/aws v1.43.0
 	go.opentelemetry.io/contrib/propagators/b3 v1.43.0
 	go.opentelemetry.io/contrib/propagators/jaeger v1.43.0
@@ -185,14 +186,12 @@ require (
 	github.com/secure-systems-lab/go-securesystemslib v0.10.0 // indirect
 	github.com/segmentio/asm v1.2.1 // indirect
 	github.com/shirou/gopsutil/v4 v4.26.3 // indirect
-	github.com/stretchr/testify v1.11.1 // indirect
 	github.com/tinylib/msgp v1.6.3 // indirect
 	github.com/tklauser/go-sysconf v0.3.16 // indirect
 	github.com/tklauser/numcpus v0.11.0 // indirect
 	github.com/trailofbits/go-mutexasserts v0.0.0-20250514102930-c1f3d2e37561 // indirect
 	github.com/urfave/cli/v3 v3.8.0 // indirect
 	github.com/vektah/gqlparser/v2 v2.5.32 // indirect
-	github.com/wolfeidau/quickzip v1.0.2 // indirect
 	github.com/yusufpapurcu/wmi v1.2.4 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/collector/component v1.55.0 // indirect

go.sum

@@ -166,8 +166,6 @@ github.com/buildkite/shellwords v1.0.1 h1:88OjMbEBf+EliVB0tizXJynpAM2CKOvYwepg5n
 github.com/buildkite/shellwords v1.0.1/go.mod h1:so0eQnTxgbo58CTYX+4BCx5UuMzvRha9dcKdCKl6NV4=
 github.com/buildkite/test-engine-client/v2 v2.5.1 h1:2Bx+UxKxsbyVB4pixuUMeevvoATrfYO7DKUpg3iI3jc=
 github.com/buildkite/test-engine-client/v2 v2.5.1/go.mod h1:JA61MSQxGU9GYx0CyED17ex83RSzcKI3LR3RVyuaH7M=
-github.com/buildkite/zstash v0.8.0 h1:z8hBGGKIaN/UX0MZh51P8s28mWaDBkgD3uMoOu6Q96g=
-github.com/buildkite/zstash v0.8.0/go.mod h1:60v4pl8PnsVA6b09MC47aTR8Z1QNJoeQqOGp2jkEww8=
 github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
 github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/cenkalti/backoff/v5 v5.0.3 h1:ZN+IMa753KfX5hd8vVaMixjnqRZ3y8CuJKRKj1xcsSM=

internal/cache/cache.go

@@ -8,11 +8,11 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/buildkite/agent/v3/internal/zstash"
+	"github.com/buildkite/agent/v3/internal/zstash/api"
+	"github.com/buildkite/agent/v3/internal/zstash/cache"
 	"github.com/buildkite/agent/v3/logger"
 	"github.com/buildkite/agent/v3/version"
-	"github.com/buildkite/zstash"
-	"github.com/buildkite/zstash/api"
-	"github.com/buildkite/zstash/cache"
 	"github.com/dustin/go-humanize"
 	"gopkg.in/yaml.v3"
 )

internal/cache/cache_test.go

@@ -10,9 +10,9 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/buildkite/agent/v3/internal/zstash"
+	"github.com/buildkite/agent/v3/internal/zstash/cache"
 	"github.com/buildkite/agent/v3/logger"
-	"github.com/buildkite/zstash"
-	"github.com/buildkite/zstash/cache"
 	"github.com/google/go-cmp/cmp"
 )