diff --git a/cmd/deep-gen/main.go b/cmd/deep-gen/main.go
index 388f2bd..d0367ab 100644
--- a/cmd/deep-gen/main.go
+++ b/cmd/deep-gen/main.go
@@ -487,7 +487,6 @@ import (
 {{- end}}
 {{- if .NeedsDeep}}
 	deep "github.com/brunoga/deep/v5"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 {{- end}}
 {{- if .NeedsCrdt}}
 	crdt "github.com/brunoga/deep/v5/crdt"
@@ -515,7 +514,7 @@ func (t *{{.TypeName}}) Patch(p {{.P}}Patch[{{.TypeName}}], logger *slog.Logger)
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := {{.P}}ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/cmd/deep-gen/main_test.go b/cmd/deep-gen/main_test.go
index e3b67c9..6f60d0a 100644
--- a/cmd/deep-gen/main_test.go
+++ b/cmd/deep-gen/main_test.go
@@ -1,9 +1,12 @@
 package main
 
 import (
+	"go/parser"
+	"go/token"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
 )
@@ -43,3 +46,44 @@ func TestGeneratorOutput(t *testing.T) {
 		t.Errorf("generator output does not match golden file\nwant:\n%s\n\ngot:\n%s", goldenStr, gotStr)
 	}
 }
+
+// TestGeneratedCodeHasNoInternalImports asserts that code emitted by deep-gen
+// never imports an internal/... package of this module. Such imports compile
+// inside the module but break for any downstream user — see the bug fixed by
+// exposing deep.ApplyOpReflection as a public wrapper around the engine's
+// reflection fallback.
+func TestGeneratedCodeHasNoInternalImports(t *testing.T) {
+	tmpDir := t.TempDir()
+	genBin := filepath.Join(tmpDir, "deep-gen")
+	if out, err := exec.Command("go", "build", "-o", genBin, ".").CombinedOutput(); err != nil {
+		t.Fatalf("build deep-gen: %v\n%s", err, out)
+	}
+
+	// internal/testmodels is rich enough to exercise the reflection fallback
+	// (which is what previously dragged the internal/engine import in).
+	outFile := filepath.Join(tmpDir, "user_deep.go")
+	if out, err := exec.Command(genBin, "-type=User,Detail", "-output", outFile, "../../internal/testmodels").CombinedOutput(); err != nil {
+		t.Fatalf("run deep-gen: %v\n%s", err, out)
+	}
+
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, outFile, nil, parser.ImportsOnly)
+	if err != nil {
+		t.Fatalf("parse generated file: %v", err)
+	}
+
+	const modulePrefix = "github.com/brunoga/deep/v5/"
+	for _, imp := range file.Imports {
+		path, err := strconv.Unquote(imp.Path.Value)
+		if err != nil {
+			t.Fatalf("unquote import %q: %v", imp.Path.Value, err)
+		}
+		if !strings.HasPrefix(path, modulePrefix) {
+			continue
+		}
+		rel := strings.TrimPrefix(path, modulePrefix)
+		if rel == "internal" || strings.HasPrefix(rel, "internal/") || strings.Contains(rel, "/internal/") {
+			t.Errorf("generated code imports internal package %q; expose a public wrapper instead", path)
+		}
+	}
+}
diff --git a/engine.go b/engine.go
index 7a2f1b3..03ece6a 100644
--- a/engine.go
+++ b/engine.go
@@ -31,6 +31,16 @@ func WithLogger(l *slog.Logger) ApplyOption {
 	return func(c *applyConfig) { c.logger = l }
 }
 
+// ApplyOpReflection applies a single Operation to target using reflection.
+//
+// This is intended for use by code generated by deep-gen as a fallback for
+// operations the generated fast-path does not handle (e.g. slice index or map
+// key paths). It is not part of the stable user-facing API; prefer [Apply]
+// for normal use.
+func ApplyOpReflection[T any](target *T, op Operation, logger *slog.Logger) error {
+	return engine.ApplyOpReflection(target, op, logger)
+}
+
 // Apply applies a Patch to a target pointer.
 // v5 prioritizes the generated Patch method but falls back to reflection if needed.
 //
diff --git a/examples/atomic_config/proxyconfig_deep.go b/examples/atomic_config/proxyconfig_deep.go
index 2efca95..851414f 100644
--- a/examples/atomic_config/proxyconfig_deep.go
+++ b/examples/atomic_config/proxyconfig_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *ProxyConfig) Patch(p deep.Patch[ProxyConfig], logger *slog.Logger) erro
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
@@ -309,7 +308,7 @@ func (t *SystemMeta) Patch(p deep.Patch[SystemMeta], logger *slog.Logger) error
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/audit_logging/user_deep.go b/examples/audit_logging/user_deep.go
index 2ee2ee2..e970ee4 100644
--- a/examples/audit_logging/user_deep.go
+++ b/examples/audit_logging/user_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 	"strings"
@@ -32,7 +31,7 @@ func (t *User) Patch(p deep.Patch[User], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/concurrent_updates/stock_deep.go b/examples/concurrent_updates/stock_deep.go
index ece9251..44c6cf8 100644
--- a/examples/concurrent_updates/stock_deep.go
+++ b/examples/concurrent_updates/stock_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *Stock) Patch(p deep.Patch[Stock], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/config_manager/config_deep.go b/examples/config_manager/config_deep.go
index 838a797..4fded8b 100644
--- a/examples/config_manager/config_deep.go
+++ b/examples/config_manager/config_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 	"strings"
@@ -32,7 +31,7 @@ func (t *Config) Patch(p deep.Patch[Config], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/http_patch_api/resource_deep.go b/examples/http_patch_api/resource_deep.go
index f1d7672..b8bee12 100644
--- a/examples/http_patch_api/resource_deep.go
+++ b/examples/http_patch_api/resource_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *Resource) Patch(p deep.Patch[Resource], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/json_interop/uistate_deep.go b/examples/json_interop/uistate_deep.go
index 4ba2fd6..b2751f6 100644
--- a/examples/json_interop/uistate_deep.go
+++ b/examples/json_interop/uistate_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *UIState) Patch(p deep.Patch[UIState], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/keyed_inventory/inventory_deep.go b/examples/keyed_inventory/inventory_deep.go
index 16fafcb..dc0235a 100644
--- a/examples/keyed_inventory/inventory_deep.go
+++ b/examples/keyed_inventory/inventory_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *Item) Patch(p deep.Patch[Item], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
@@ -309,7 +308,7 @@ func (t *Inventory) Patch(p deep.Patch[Inventory], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/multi_error/strictuser_deep.go b/examples/multi_error/strictuser_deep.go
index b2442db..6b1f594 100644
--- a/examples/multi_error/strictuser_deep.go
+++ b/examples/multi_error/strictuser_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *StrictUser) Patch(p deep.Patch[StrictUser], logger *slog.Logger) error
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/policy_engine/employee_deep.go b/examples/policy_engine/employee_deep.go
index 48b96b2..ce03ed8 100644
--- a/examples/policy_engine/employee_deep.go
+++ b/examples/policy_engine/employee_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 )
@@ -31,7 +30,7 @@ func (t *Employee) Patch(p deep.Patch[Employee], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/state_management/docstate_deep.go b/examples/state_management/docstate_deep.go
index ff200b5..7e77670 100644
--- a/examples/state_management/docstate_deep.go
+++ b/examples/state_management/docstate_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 	"strings"
@@ -32,7 +31,7 @@ func (t *DocState) Patch(p deep.Patch[DocState], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/struct_map_keys/fleet_deep.go b/examples/struct_map_keys/fleet_deep.go
index 165dbc6..1b84ff2 100644
--- a/examples/struct_map_keys/fleet_deep.go
+++ b/examples/struct_map_keys/fleet_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 )
 
@@ -30,7 +29,7 @@ func (t *Fleet) Patch(p deep.Patch[Fleet], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/three_way_merge/systemconfig_deep.go b/examples/three_way_merge/systemconfig_deep.go
index f14d549..9436776 100644
--- a/examples/three_way_merge/systemconfig_deep.go
+++ b/examples/three_way_merge/systemconfig_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 	"strings"
@@ -32,7 +31,7 @@ func (t *SystemConfig) Patch(p deep.Patch[SystemConfig], logger *slog.Logger) er
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/examples/websocket_sync/gameworld_deep.go b/examples/websocket_sync/gameworld_deep.go
index 9aad386..87888ba 100644
--- a/examples/websocket_sync/gameworld_deep.go
+++ b/examples/websocket_sync/gameworld_deep.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 	"strings"
@@ -32,7 +31,7 @@ func (t *GameWorld) Patch(p deep.Patch[GameWorld], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
@@ -314,7 +313,7 @@ func (t *Player) Patch(p deep.Patch[Player], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
diff --git a/internal/testmodels/user_deep.go b/internal/testmodels/user_deep.go
index 70fa749..e4d1589 100644
--- a/internal/testmodels/user_deep.go
+++ b/internal/testmodels/user_deep.go
@@ -6,7 +6,6 @@ import (
 	deep "github.com/brunoga/deep/v5"
 	"github.com/brunoga/deep/v5/condition"
 	crdt "github.com/brunoga/deep/v5/crdt"
-	_deepengine "github.com/brunoga/deep/v5/internal/engine"
 	"log/slog"
 	"regexp"
 	"strings"
@@ -33,7 +32,7 @@ func (t *User) Patch(p deep.Patch[User], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}
@@ -564,7 +563,7 @@ func (t *Detail) Patch(p deep.Patch[Detail], logger *slog.Logger) error {
 		if err != nil {
 			errs = append(errs, err)
 		} else if !handled {
-			if err := _deepengine.ApplyOpReflection(t, op, logger); err != nil {
+			if err := deep.ApplyOpReflection(t, op, logger); err != nil {
 				errs = append(errs, err)
 			}
 		}