diff --git a/src/drt/BUILD b/src/drt/BUILD
index be713569a38..1e7aee6cfec 100644
--- a/src/drt/BUILD
+++ b/src/drt/BUILD
@@ -24,7 +24,10 @@ cc_library(
 cc_library(
     name = "base_types",
     srcs = ["src/frBaseTypes.cpp"],
-    hdrs = ["src/frBaseTypes.h"],
+    hdrs = [
+        "src/dr/FlexMazeTypes.h",
+        "src/frBaseTypes.h",
+    ],
     includes = ["src"],
     deps = [
         "//src/odb/src/db",
@@ -91,11 +94,11 @@ cc_library(
         "src/db/tech/frTechObject.h",
         "src/db/tech/frViaDef.h",
         "src/db/tech/frViaRuleGenerate.h",
-        "src/dr/FlexMazeTypes.h",
     ],
     includes = [
         "src",
     ],
+    visibility = ["//src/drt:__subpackages__"],
     deps = [
         ":base_types",
         "//src/odb/src/db",
@@ -104,10 +107,44 @@ cc_library(
     ],
 )
 
+# Headers owned by :drt but also consumed by :ui. Kept package-private so
+# nothing outside //src/drt can depend on them.
+cc_library(
+    name = "drt_private_hdrs",
+    hdrs = [
+        "src/AbstractGraphicsFactory.h",
+        "src/distributed/drUpdate.h",
+        "src/dr/AbstractDRGraphics.h",
+        "src/dr/FlexDR.h",
+        "src/dr/FlexGridGraph.h",
+        "src/dr/FlexWavefront.h",
+        "src/frDesign.h",
+        "src/frRegionQuery.h",
+        "src/gc/FlexGC.h",
+        "src/global.h",
+        "src/pa/AbstractPAGraphics.h",
+        "src/pa/FlexPA.h",
+        "src/pa/FlexPA_unique.h",
+        "src/ta/AbstractTAGraphics.h",
+        "src/ta/FlexTA.h",
+    ],
+    includes = ["src"],
+    visibility = ["//visibility:private"],
+    deps = [
+        ":base_types",
+        ":db_hdrs",
+        "//src/dst",
+        "//src/odb/src/db",
+        "//src/utl",
+        "@boost.container",
+        "@boost.polygon",
+        "@boost.serialization",
+    ],
+)
+
 cc_library(
     name = "drt",
     srcs = [
-        "src/AbstractGraphicsFactory.h",
         "src/DesignCallBack.cpp",
         "src/DesignCallBack.h",
         "src/TritonRoute.cpp",
@@ -132,14 +169,11 @@ cc_library(
         "src/distributed/RoutingCallBack.h",
         "src/distributed/RoutingJobDescription.h",
         "src/distributed/drUpdate.cpp",
-        "src/distributed/drUpdate.h",
         "src/distributed/frArchive.cpp",
         "src/distributed/frArchive.h",
         "src/distributed/paUpdate.cpp",
         "src/distributed/paUpdate.h",
-        "src/dr/AbstractDRGraphics.h",
         "src/dr/FlexDR.cpp",
-        "src/dr/FlexDR.h",
         "src/dr/FlexDRFlow.cpp",
         "src/dr/FlexDR_conn.cpp",
         "src/dr/FlexDR_conn.h",
@@ -148,16 +182,11 @@ cc_library(
         "src/dr/FlexDR_maze.cpp",
         "src/dr/FlexDR_rq.cpp",
         "src/dr/FlexGridGraph.cpp",
-        "src/dr/FlexGridGraph.h",
         "src/dr/FlexGridGraph_maze.cpp",
-        "src/dr/FlexWavefront.h",
-        "src/frDesign.h",
         "src/frProfileTask.h",
         "src/frRTree.h",
         "src/frRegionQuery.cpp",
-        "src/frRegionQuery.h",
         "src/gc/FlexGC.cpp",
-        "src/gc/FlexGC.h",
         "src/gc/FlexGC_cut.cpp",
         "src/gc/FlexGC_eol.cpp",
         "src/gc/FlexGC_impl.h",
@@ -167,30 +196,24 @@ cc_library(
         "src/gc/FlexGC_metspc.cpp",
         "src/gc/FlexGC_rq.cpp",
         "src/global.cpp",
-        "src/global.h",
         "src/io/GuideProcessor.cpp",
         "src/io/GuideProcessor.h",
         "src/io/io.cpp",
         "src/io/io.h",
         "src/io/io_parser_helper.cpp",
         "src/io/io_pin.cpp",
-        "src/pa/AbstractPAGraphics.h",
         "src/pa/FlexPA.cpp",
-        "src/pa/FlexPA.h",
         "src/pa/FlexPA_acc_pattern.cpp",
         "src/pa/FlexPA_acc_point.cpp",
         "src/pa/FlexPA_init.cpp",
         "src/pa/FlexPA_row_pattern.cpp",
         "src/pa/FlexPA_unique.cpp",
-        "src/pa/FlexPA_unique.h",
         "src/rp/FlexRP.cpp",
         "src/rp/FlexRP.h",
         "src/rp/FlexRP_init.cpp",
         "src/rp/FlexRP_prep.cpp",
         "src/serialization.h",
-        "src/ta/AbstractTAGraphics.h",
         "src/ta/FlexTA.cpp",
-        "src/ta/FlexTA.h",
         "src/ta/FlexTA_assign.cpp",
         "src/ta/FlexTA_end.cpp",
         "src/ta/FlexTA_init.cpp",
@@ -209,6 +232,7 @@ cc_library(
     deps = [
         ":base_types",
         ":db_hdrs",
+        ":drt_private_hdrs",
         ":pin_access_service",
         "//src/dst",
         "//src/odb/src/db",
@@ -231,29 +255,13 @@ cc_library(
 cc_library(
     name = "ui",
     srcs = [
-        "include/drt/TritonRoute.h",
-        "src/AbstractGraphicsFactory.h",
         "src/GraphicsFactory.cpp",
         "src/GraphicsFactory.h",
         "src/MakeTritonRoute.cpp",
-        "src/distributed/drUpdate.h",
-        "src/dr/AbstractDRGraphics.h",
-        "src/dr/FlexDR.h",
         "src/dr/FlexDR_graphics.cpp",
         "src/dr/FlexDR_graphics.h",
-        "src/dr/FlexGridGraph.h",
-        "src/dr/FlexWavefront.h",
-        "src/frDesign.h",
-        "src/frRegionQuery.h",
-        "src/gc/FlexGC.h",
-        "src/global.h",
-        "src/pa/AbstractPAGraphics.h",
-        "src/pa/FlexPA.h",
         "src/pa/FlexPA_graphics.cpp",
         "src/pa/FlexPA_graphics.h",
-        "src/pa/FlexPA_unique.h",
-        "src/ta/AbstractTAGraphics.h",
-        "src/ta/FlexTA.h",
         "src/ta/FlexTA_graphics.cpp",
         "src/ta/FlexTA_graphics.h",
         ":swig",
@@ -273,6 +281,7 @@ cc_library(
         ":base_types",
         ":db_hdrs",
         ":drt",
+        ":drt_private_hdrs",
         ":pin_access_service",
         "//:ord",
         "//src/dst",
diff --git a/src/drt/src/dr/FlexDR.cpp b/src/drt/src/dr/FlexDR.cpp
index c86b22f17b9..6179120364b 100644
--- a/src/drt/src/dr/FlexDR.cpp
+++ b/src/drt/src/dr/FlexDR.cpp
@@ -42,6 +42,7 @@
 #include "distributed/frArchive.h"
 #include "dr/AbstractDRGraphics.h"
 #include "dr/FlexDR_conn.h"
+#include "drt/TritonRoute.h"
 #include "dst/BalancerJobDescription.h"
 #include "dst/Distributed.h"
 #include "dst/JobMessage.h"
diff --git a/src/drt/src/dr/FlexDR.h b/src/drt/src/dr/FlexDR.h
index b074e3dad55..aa12f6d3e7f 100644
--- a/src/drt/src/dr/FlexDR.h
+++ b/src/drt/src/dr/FlexDR.h
@@ -36,7 +36,6 @@
 #include "dr/FlexGridGraph.h"
 #include "dr/FlexMazeTypes.h"
 #include "dr/FlexWavefront.h"
-#include "drt/TritonRoute.h"
 #include "dst/JobMessage.h"
 #include "frBaseTypes.h"
 #include "frDesign.h"
@@ -58,6 +57,7 @@ class Logger;
 
 namespace drt {
 
+class TritonRoute;
 class frConstraint;
 struct SearchRepairArgs;