diff --git a/docs/MOD_PACKAGES.md b/docs/MOD_PACKAGES.md
index 9fad8eca..2c2ea70a 100644
--- a/docs/MOD_PACKAGES.md
+++ b/docs/MOD_PACKAGES.md
@@ -757,6 +757,13 @@ some selections of one feature is a `[[requirement]]`, not a dependency.
 
 ## Implicit requirements across packages
 
+Trusted graphics plugins can call `psx_mod_set_internal_resolution(lines)` to
+request a rendering height for their session. Values from 120 through 8192 use
+the existing integer-scale resolver and backend allocation limits; zero clears
+the request. `PSX_INTERNAL_RESOLUTION` takes precedence. The player's saved
+resolution stays unchanged, and every new session clears the request before
+its mod plan activates, including rematches and sessions without that mod.
+
 The shared PGXP plugin uses `psx_mod_set_pgxp_precision(enabled, cpu_mode)`.
 This stores a session selection as well as setting live correction flags, so
 later renderer initialization cannot erase mod activation with the base video
diff --git a/runtime/CMakeLists.txt b/runtime/CMakeLists.txt
index e324baef..a8c1d80a 100644
--- a/runtime/CMakeLists.txt
+++ b/runtime/CMakeLists.txt
@@ -1248,6 +1248,12 @@ if(BUILD_TESTING)
     endif()
     add_test(NAME render_pass_plan_test COMMAND render_pass_plan_test)
 
+    add_executable(mod_internal_resolution_test
+        tests/test_mod_internal_resolution.c
+        src/mod_internal_resolution.c)
+    target_include_directories(mod_internal_resolution_test PRIVATE include)
+    add_test(NAME mod_internal_resolution_test COMMAND mod_internal_resolution_test)
+
     # Motion kit and per-frame driver for render-pass plugins: blending,
     # identity matching, limits and the crossfade fallback, on mock RAM.
     add_executable(render_pass_motion_test
diff --git a/runtime/include/mod_internal_resolution.h b/runtime/include/mod_internal_resolution.h
new file mode 100644
index 00000000..e81c6a4a
--- /dev/null
+++ b/runtime/include/mod_internal_resolution.h
@@ -0,0 +1,17 @@
+#ifndef PSX_MOD_INTERNAL_RESOLUTION_H
+#define PSX_MOD_INTERNAL_RESOLUTION_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Runtime session plumbing; plugins use mod_plugins.h. Zero means no request. */
+uint32_t psx_mod_internal_resolution_request(void);
+void psx_mod_internal_resolution_reset(void);
+
+#ifdef __cplusplus
+}
+#endif
+#endif
diff --git a/runtime/include/mod_plugins.h b/runtime/include/mod_plugins.h
index 353d298b..61fbbf4c 100644
--- a/runtime/include/mod_plugins.h
+++ b/runtime/include/mod_plugins.h
@@ -431,6 +431,13 @@ int psx_mod_set_adaptive_display_aspect(uint32_t max_numerator,
  * title's setting before activation.
  */
 int psx_mod_set_widescreen_hud_size(int proportional);
+/* Request an internal rendering height for this mod session (120..8192).
+ * The existing resolution resolver selects an integer raster scale and the
+ * backend applies its normal allocation limits. Zero clears the request.
+ * Player settings are preserved, explicit PSX_INTERNAL_RESOLUTION overrides
+   * win, and each session clears this request before activating its committed
+   * mod plan. */
+int psx_mod_set_internal_resolution(uint32_t target_lines);
 /*
  * Set the wall-clock cadence of simulated guest VBlanks. A value of zero
  * removes frontend pacing; 60 and higher request that many native guest
diff --git a/runtime/runtime.cmake b/runtime/runtime.cmake
index 06ed5efd..57ceae34 100644
--- a/runtime/runtime.cmake
+++ b/runtime/runtime.cmake
@@ -472,6 +472,7 @@ set(PSXRECOMP_RUNTIME_SOURCES
     ${PSXRECOMP_ROOT}/runtime/src/game_options.c
     ${PSXRECOMP_ROOT}/runtime/src/mod_builtin_speed.c
     ${PSXRECOMP_ROOT}/runtime/src/mod_builtin_pgxp.c
+    ${PSXRECOMP_ROOT}/runtime/src/mod_internal_resolution.c
     ${PSXRECOMP_ROOT}/runtime/src/mod_builtin_bezel.c
     ${PSXRECOMP_ROOT}/runtime/src/mod_builtin_ram.c
     ${PSXRECOMP_ROOT}/runtime/src/mod_builtin_hd_textures.c
diff --git a/runtime/src/main.cpp b/runtime/src/main.cpp
index c94e99de..d6dfb162 100644
--- a/runtime/src/main.cpp
+++ b/runtime/src/main.cpp
@@ -11,6 +11,7 @@
 #include "mod_controller_source.h"
 #include "window_size.h"     /* default game-window size */
 #include "internal_resolution.h" /* Settings -> Display -> Internal resolution */
+#include "mod_internal_resolution.h"
 #include "dynamic_resolution.h"  /* [video] dynamic_resolution: the step controller */
 #include "render_thread.h"        /* rt_get_stats: queue backpressure (dynres) */
 #include "psx_scheduler.h"   /* psx_scheduler_run — deterministic TCB scheduler */
@@ -1362,11 +1363,11 @@ static int video_scale_ceiling(void) {
     return g_video_renderer == 1 ? GL_MAX_INTERNAL_SCALE : SW_MAX_INTERNAL_SCALE;
 }
 
-/* The preset in effect this run: the environment override, else the
- * configured one. */
+/* Session priority: environment override, active mod request, player setting. */
 static int effective_internal_resolution(void) {
+    const uint32_t mod_lines = psx_mod_internal_resolution_request();
     return g_video_internal_res_env != PSX_IR_UNSET ? g_video_internal_res_env
-                                                    : g_video_internal_res;
+        : mod_lines ? (int)mod_lines : g_video_internal_res;
 }
 
 /* Resolve the Internal resolution preset into g_video_scale. display_px_h is
@@ -1703,6 +1704,7 @@ extern "C" int psx_mod_set_adaptive_display_aspect(
 static PSXModSessionBaseline g_mod_owned_baseline;
 
 static void reset_mod_owned_presentation(void) {
+    psx_mod_internal_resolution_reset();
     psx_local_mouse_clear();
     PSXModSessionScalars live;
     live.video_vsync = g_video_vsync;
diff --git a/runtime/src/mod_internal_resolution.c b/runtime/src/mod_internal_resolution.c
new file mode 100644
index 00000000..b272c902
--- /dev/null
+++ b/runtime/src/mod_internal_resolution.c
@@ -0,0 +1,19 @@
+#include "mod_plugins.h"
+#include "mod_internal_resolution.h"
+
+static uint32_t requested_lines;
+
+int psx_mod_set_internal_resolution(uint32_t target_lines) {
+    if (target_lines && (target_lines < 120u || target_lines > 8192u))
+        return 0;
+    requested_lines = target_lines;
+    return 1;
+}
+
+uint32_t psx_mod_internal_resolution_request(void) {
+    return requested_lines;
+}
+
+void psx_mod_internal_resolution_reset(void) {
+    requested_lines = 0;
+}
diff --git a/runtime/tests/test_mod_internal_resolution.c b/runtime/tests/test_mod_internal_resolution.c
new file mode 100644
index 00000000..f33ce426
--- /dev/null
+++ b/runtime/tests/test_mod_internal_resolution.c
@@ -0,0 +1,25 @@
+#include "mod_plugins.h"
+#include "mod_internal_resolution.h"
+#include <stdio.h>
+
+#define CHECK(x) do { if (!(x)) { fprintf(stderr, "Failed: %s\n", #x); return 1; } } while (0)
+
+int main(void) {
+    /* Disabled sessions retain the configured baseline; a later launch must
+     * not inherit an earlier active graphics mod's requested height. */
+    CHECK(psx_mod_internal_resolution_request() == 0u);
+    CHECK(psx_mod_set_internal_resolution(1080u));
+    CHECK(psx_mod_internal_resolution_request() == 1080u);
+    CHECK(!psx_mod_set_internal_resolution(119u));
+    CHECK(!psx_mod_set_internal_resolution(8193u));
+    CHECK(!psx_mod_set_internal_resolution(UINT32_MAX));
+    CHECK(psx_mod_internal_resolution_request() == 1080u);
+    psx_mod_internal_resolution_reset();
+    CHECK(psx_mod_internal_resolution_request() == 0u);
+    CHECK(psx_mod_set_internal_resolution(120u));
+    CHECK(psx_mod_set_internal_resolution(8192u));
+    CHECK(psx_mod_set_internal_resolution(0u));
+    CHECK(psx_mod_internal_resolution_request() == 0u);
+    puts("session-scoped mod resolution validation passed");
+    return 0;
+}