diff --git a/.github/workflows/build-cache.yml b/.github/workflows/build-cache.yml
index e162ad540..60fa951a3 100644
--- a/.github/workflows/build-cache.yml
+++ b/.github/workflows/build-cache.yml
@@ -28,7 +28,7 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: "1.27.2"
+          go-version: "1.27.3"
       - name: Verify Buildx selection and cache arguments reach the docker CLI
         if: matrix.language == 'go'
         run: go test ./agents/helpers/docker -run '^TestBuildx|^TestBuildOmits|^TestBuildCarries' -count=1 -v -timeout=5m
@@ -62,7 +62,7 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: "1.27.2"
+          go-version: "1.27.3"
       - uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
         with:
           name: registry-cache-${{ matrix.language }}
diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index f59d7bc67..fa71fac6e 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -112,7 +112,7 @@ jobs:
       - name: set up
         uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: "1.27.2"
+          go-version: "1.27.3"
 
       - name: checkout
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
diff --git a/agents/services/builder.go b/agents/services/builder.go
index 8c0f44f52..611351402 100644
--- a/agents/services/builder.go
+++ b/agents/services/builder.go
@@ -58,7 +58,13 @@ func (b *BuilderAgent) Build(ctx context.Context, req *builderv0.BuildRequest, o
 	if err == nil && cache != nil && resp.GetState().GetState() == builderv0.BuildStatus_SUCCESS && resp.GetResult().GetDockerBuildPlan() == nil && resp.GetCacheContractVersion() != dockerhelpers.CacheContractVersion {
 		return nil, fmt.Errorf("builder agent did not acknowledge build cache contract %s; upgrade the agent or remove cache options", dockerhelpers.CacheContractVersion)
 	}
-	if selected != "" && err == nil && resp.GetState().GetState() == builderv0.BuildStatus_SUCCESS && resp.GetResult().GetDockerBuildPlan() == nil && resp.GetBuildxBuilder() != selected {
+	// Only an in-agent image build has an executor to acknowledge. A recipe
+	// (docker_build_plan) is built by the caller, on the builder it selected;
+	// an answer with no result kind built nothing — a vendor-image agent whose
+	// image is published elsewhere — and has nothing to acknowledge either.
+	// Reading "no recipe" as "built in-agent" refused every render composing
+	// such an agent the moment the environment selected a builder.
+	if selected != "" && err == nil && resp.GetState().GetState() == builderv0.BuildStatus_SUCCESS && resp.GetResult().GetDockerBuildResult() != nil && resp.GetBuildxBuilder() != selected {
 		return nil, fmt.Errorf("builder agent did not acknowledge requested Buildx builder %q; upgrade the agent", selected)
 	}
 	if err == nil && req.GetExecution() != nil {
diff --git a/agents/services/builder_cache_test.go b/agents/services/builder_cache_test.go
index f5c5f3d23..149bc799b 100644
--- a/agents/services/builder_cache_test.go
+++ b/agents/services/builder_cache_test.go
@@ -2,7 +2,6 @@ package services
 
 import (
 	"context"
-	"fmt"
 	"net"
 	"sync/atomic"
 	"testing"
@@ -87,12 +86,21 @@ func (s *buildxTestServer) Build(ctx context.Context, req *builderv0.BuildReques
 	return resp, err
 }
 
+// Only an in-agent build has an executor to acknowledge: a recipe is built by
+// the caller on the builder it selected, and an answer that built nothing (a
+// vendor-image agent) has nothing to acknowledge. Treating "no recipe" as
+// "built in-agent" refused every render composing a vendor-image agent.
 func TestBuildxSelectionRequiresExecutorAcknowledgementOverGRPC(t *testing.T) {
-	for _, recipe := range []bool{false, true} {
-		t.Run(fmt.Sprintf("recipe=%t", recipe), func(t *testing.T) {
+	for name, result := range map[string]*builderv0.BuildResult{
+		"in-agent build": {Kind: &builderv0.BuildResult_DockerBuildResult{DockerBuildResult: &builderv0.DockerBuildResult{}}},
+		"recipe":         {Kind: &builderv0.BuildResult_DockerBuildPlan{DockerBuildPlan: &builderv0.DockerBuildPlan{}}},
+		"nothing built":  nil,
+	} {
+		t.Run(name, func(t *testing.T) {
+			recipe := name != "in-agent build"
 			wrapper := &BuilderWrapper{Base: &Base{loaded: true}}
-			if recipe {
-				wrapper.BuildResult = &builderv0.BuildResult{Kind: &builderv0.BuildResult_DockerBuildPlan{DockerBuildPlan: &builderv0.DockerBuildPlan{}}}
+			if result != nil {
+				wrapper.BuildResult = result
 			}
 			server := grpc.NewServer()
 			builderv0.RegisterBuilderServer(server, &buildxTestServer{
@@ -144,7 +152,7 @@ func TestBuildxCapabilitiesCheckedBeforeBuildOverGRPC(t *testing.T) {
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			implementation := &buildxTestServer{
-				DefaultBuilder:  NewDefaultBuilder(&BuilderWrapper{Base: &Base{loaded: true}}),
+				DefaultBuilder:  NewDefaultBuilder(&BuilderWrapper{Base: &Base{loaded: true}, BuildResult: &builderv0.BuildResult{Kind: &builderv0.BuildResult_DockerBuildResult{DockerBuildResult: &builderv0.DockerBuildResult{}}}}), // an in-agent build: the one answer that owes an acknowledgement
 				capabilities:    &builderv0.BuildCapabilitiesResponse{BuildxSelection: tc.supported},
 				capabilityError: tc.probeError,
 				acknowledgement: tc.ack,
diff --git a/go.mod b/go.mod
index cb90dfc38..dd72734c9 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/codefly-dev/core
 
-go 1.27.0
+go 1.27.3
 
 require (
 	buf.build/gen/go/bufbuild/protovalidate/protocolbuffers/go v1.36.12-20260825204119-511051f7f437.2
diff --git a/runners/sandbox/bwrap.go b/runners/sandbox/bwrap.go
index 29e854899..8a9eb6508 100644
--- a/runners/sandbox/bwrap.go
+++ b/runners/sandbox/bwrap.go
@@ -12,6 +12,7 @@ import (
 //	bwrap \
 //	  --die-with-parent \
 //	  --new-session \
+//	  --unshare-pid \
 //	  --proc /proc \
 //	  --dev /dev \
 //	  --tmpfs /tmp \
@@ -24,9 +25,18 @@ import (
 //	  [--unshare-net]
 //	  -- <originalCmd> <originalArgs...>
 //
-// `--die-with-parent` ensures the bwrap child gets SIGTERM if the Go
+// `--die-with-parent` asks for the bwrap child to be killed if the Go
 // parent dies abnormally. `--new-session` blocks TIOCSTI escapes from
-// the sandboxed process onto the controlling tty. The system-image
+// the sandboxed process onto the controlling tty. `--unshare-pid` is
+// what actually bounds the payload's lifetime: with it the payload runs
+// under a pid-namespace init bubblewrap supervises, so ending the
+// supervisor ends the namespace and every process in it. Without it the
+// bound rests on the parent-death signal alone, and that signal is not
+// delivered on every platform: on Ubuntu 26.04 (kernel 7.0, bubblewrap
+// 0.11.1 confined as bwrap//&unpriv_bwrap) a payload outlived its
+// terminated supervisor, in its own session because of --new-session,
+// holding the supervisor's stdio pipes, so the caller's reaper never
+// returned and cleanup ran into its deadline. The system-image
 // binds (/usr, /lib, etc.) are required because most binaries are
 // dynamically linked to libraries rooted there; without them, even
 // `cat` fails to start in the sandbox.
@@ -108,6 +118,7 @@ func (s *bwrapSandbox) buildArgs() []string {
 	args := []string{
 		"--die-with-parent",
 		"--new-session",
+		"--unshare-pid",
 		"--proc", "/proc",
 		"--dev", "/dev",
 		"--tmpfs", "/tmp",
diff --git a/runners/sandbox/sandbox_test.go b/runners/sandbox/sandbox_test.go
index c43929725..8e8484ff5 100644
--- a/runners/sandbox/sandbox_test.go
+++ b/runners/sandbox/sandbox_test.go
@@ -202,6 +202,21 @@ func TestBwrap_NetworkLoopback_UsesIsolatedNetwork(t *testing.T) {
 	require.Equal(t, []string{"/tmp/codefly-agent", "--fixture"}, cmd.Args[len(cmd.Args)-2:])
 }
 
+func TestBwrapPayloadLifetimeIsBoundToAPidNamespace(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		// bubblewrap is Linux-only; returning early per the no-skip rule.
+		return
+	}
+	sb, err := sandbox.New()
+	require.NoError(t, err)
+	cmd := exec.Command("/tmp/codefly-agent", "--fixture")
+	require.NoError(t, sb.Wrap(cmd))
+	args := strings.Join(cmd.Args, " ")
+	require.Contains(t, args, "--unshare-pid",
+		"the payload must run under a pid-namespace init bubblewrap supervises: --die-with-parent alone is not honoured on every platform (Ubuntu 26.04 let a payload outlive its terminated supervisor)")
+	require.Contains(t, args, "--die-with-parent")
+}
+
 func TestSandbox_Wrap_RefusesDoubleWrap(t *testing.T) {
 	sb, err := sandbox.New()
 	if err != nil {