diff --git a/cmd/executor.go b/cmd/executor.go
index 5c8d265..3e95dfe 100644
--- a/cmd/executor.go
+++ b/cmd/executor.go
@@ -100,10 +100,21 @@ func upLocal(opts upLocalOpts) error {
 		return fmt.Errorf("rendering payload: %w", err)
 	}
 
-	// Resolve payload entries into upload pairs
+	// Resolve payload entries into upload pairs. Inline content payloads are
+	// written to temp files that are uploaded individually by their own
+	// sandbox_path, so their source paths must survive until SandboxCreate.
+	// They MUST NOT live inside payloadDir: createSandbox renames payloadDir
+	// into a staging directory, which would invalidate any path pointing inside
+	// it and fail every upload with "local path does not exist" (issue #84).
 	var extraUploads []gateway.Upload
 	if opts.harness != nil && len(opts.harness.Payloads) > 0 {
-		resolved, err := agent.ResolvePayloads(opts.harness.Payloads, opts.harnessDir, payloadDir)
+		contentDir, err := os.MkdirTemp("", "harness-payload-content-")
+		if err != nil {
+			return fmt.Errorf("creating payload content dir: %w", err)
+		}
+		defer os.RemoveAll(contentDir)
+
+		resolved, err := agent.ResolvePayloads(opts.harness.Payloads, opts.harnessDir, contentDir)
 		if err != nil {
 			return fmt.Errorf("resolving payloads: %w", err)
 		}
diff --git a/cmd/executor_test.go b/cmd/executor_test.go
index 0bcb15b..ee95520 100644
--- a/cmd/executor_test.go
+++ b/cmd/executor_test.go
@@ -8,6 +8,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/stackrox/harness-openshell/internal/agent"
 	"github.com/stackrox/harness-openshell/internal/gateway"
 )
 
@@ -264,3 +265,50 @@ providers:
 		t.Fatal("expected error for --agent research when file doesn't exist, should not fall back to embedded")
 	}
 }
+
+// TestUpLocal_InlineContentPayloadPathSurvivesRename is a regression test for
+// issue #84: inline content payloads were written into payloadDir, which
+// createSandbox renames into a staging directory. The rename invalidated the
+// stored upload paths, so every SandboxCreate failed with "local path does not
+// exist". The fix stages inline content in a separate temp dir that survives
+// the rename — so every upload Src must still resolve at create time.
+func TestUpLocal_InlineContentPayloadPathSurvivesRename(t *testing.T) {
+	dir := setupTestAgent(t)
+
+	var uploadsChecked bool
+	gw := &mockGW{
+		providers: map[string]bool{"github": true, "google-vertex-ai": true, "atlassian": true},
+		onSandboxCreate: func(opts gateway.SandboxCreateOpts) error {
+			for _, u := range opts.Uploads {
+				if _, err := os.Stat(u.Src); err != nil {
+					return fmt.Errorf("upload Src %q not accessible at create time: %w", u.Src, err)
+				}
+			}
+			uploadsChecked = true
+			return nil
+		},
+	}
+
+	harness := &agent.Harness{
+		Payloads: []agent.PayloadEntry{
+			{SandboxPath: "/sandbox/opencode.json", Content: `{"model": "test"}`},
+		},
+	}
+
+	err := upLocal(upLocalOpts{
+		harnessDir: dir,
+		gw:         gw,
+		agentPath:  filepath.Join(dir, "agents", "default.yaml"),
+		noTTY:      true,
+		harness:    harness,
+	})
+	if err != nil {
+		t.Fatalf("upLocal: %v", err)
+	}
+	if !uploadsChecked {
+		t.Fatal("SandboxCreate was not called; upload paths were never validated")
+	}
+	if gw.createCalls != 1 {
+		t.Fatalf("expected exactly 1 SandboxCreate call, got %d", gw.createCalls)
+	}
+}
diff --git a/cmd/helpers_test.go b/cmd/helpers_test.go
index 386a7bc..ba35721 100644
--- a/cmd/helpers_test.go
+++ b/cmd/helpers_test.go
@@ -28,6 +28,7 @@ type mockGW struct {
 	deletedNames      []string
 	gatewayListResult []gateway.GatewayInfo
 	onGatewayRemove   func(string)
+	onSandboxCreate   func(gateway.SandboxCreateOpts) error
 }
 
 func (m *mockGW) InferenceGet() error { return m.inferenceErr }
@@ -41,6 +42,11 @@ func (m *mockGW) ProviderList() ([]string, error) { return m.providerList, m.pro
 func (m *mockGW) SandboxCreate(opts gateway.SandboxCreateOpts) error {
 	m.createCalls++
 	m.createOpts = append(m.createOpts, opts)
+	if m.onSandboxCreate != nil {
+		if err := m.onSandboxCreate(opts); err != nil {
+			return err
+		}
+	}
 	if m.createErr != nil && m.createCalls == 1 {
 		return m.createErr
 	}