From f6fc95d0460ce51b8453c63beab4271da159adf7 Mon Sep 17 00:00:00 2001
From: "torlando-agent[bot]"
 <281092095+torlando-agent[bot]@users.noreply.github.com>
Date: Tue, 11 Aug 2026 01:19:07 +0000
Subject: [PATCH] fix: prevent tile worker starvation on unchanged map model

---
 lib/tdeck_ui/UI/LXMF/MapScreen.cpp            |  4 ++-
 lib/tdeck_ui/UI/LXMF/MapScreenPresenter.h     |  1 +
 .../build_scripts/test_map_screen_contract.py | 11 ++++++++
 tests/native/test_map_screen_presenter.cpp    | 27 +++++++++++++++++++
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/lib/tdeck_ui/UI/LXMF/MapScreen.cpp b/lib/tdeck_ui/UI/LXMF/MapScreen.cpp
index 1a9508b0..933247e2 100644
--- a/lib/tdeck_ui/UI/LXMF/MapScreen.cpp
+++ b/lib/tdeck_ui/UI/LXMF/MapScreen.cpp
@@ -620,7 +620,9 @@ void MapScreen::updateModel(const Pyxis::MapView::Request& request) {
         presenter_.recenter(true, request.local_location)) {
         center_initialized_ = true;
     }
-    requests_released_ = false;
+    if (!presenter_.frameBuiltForCurrentEpoch()) {
+        requests_released_ = false;
+    }
     (void)presenter_.buildFrame(request);
     unlockState();
 }
diff --git a/lib/tdeck_ui/UI/LXMF/MapScreenPresenter.h b/lib/tdeck_ui/UI/LXMF/MapScreenPresenter.h
index fe9fc3ce..075c05ff 100644
--- a/lib/tdeck_ui/UI/LXMF/MapScreenPresenter.h
+++ b/lib/tdeck_ui/UI/LXMF/MapScreenPresenter.h
@@ -102,6 +102,7 @@ public:
     std::uint32_t zoom() const { return zoom_; }
     std::uint32_t generation() const { return generation_; }
     std::uint32_t frameEpoch() const { return frame_epoch_; }
+    bool frameBuiltForCurrentEpoch() const { return frame_built_for_epoch_; }
     std::size_t requestCount() const { return request_count_; }
     std::size_t completionCount() const { return completion_count_; }
 
diff --git a/tests/build_scripts/test_map_screen_contract.py b/tests/build_scripts/test_map_screen_contract.py
index 6ad16e26..2ea37e2f 100644
--- a/tests/build_scripts/test_map_screen_contract.py
+++ b/tests/build_scripts/test_map_screen_contract.py
@@ -77,6 +77,17 @@ def test_worker_predecodes_and_render_path_has_no_io():
     assert "MAX_COMPLETIONS_PER_TICK = 1" in text(UI / "MapScreen.h")
 
 
+def test_unchanged_model_does_not_starve_released_tile_requests():
+    source = text(UI / "MapScreen.cpp")
+    presenter = text(UI / "MapScreenPresenter.h")
+    update = function_body(source, "void MapScreen::updateModel(")
+    assert "frameBuiltForCurrentEpoch" in presenter
+    guard = update.index("if (!presenter_.frameBuiltForCurrentEpoch())")
+    revoke = update.index("requests_released_ = false")
+    build = update.index("presenter_.buildFrame(request)")
+    assert guard < revoke < build
+
+
 def test_selected_pack_is_the_only_sd_tile_source():
     source = text(UI / "MapScreen.cpp")
     header = text(UI / "MapScreen.h")
diff --git a/tests/native/test_map_screen_presenter.cpp b/tests/native/test_map_screen_presenter.cpp
index af568122..ac0db32e 100644
--- a/tests/native/test_map_screen_presenter.cpp
+++ b/tests/native/test_map_screen_presenter.cpp
@@ -67,6 +67,32 @@ void fixedCapacityAndDedupe() {
     }
 }
 
+void frameBuildLifecycleKeepsReleasedWorkAvailable() {
+    MapScreenPresenter presenter;
+    presenter.show();
+    CHECK(!presenter.frameBuiltForCurrentEpoch());
+    CHECK(presenter.buildFrame(requestAt(0.0, 0.0, 3)) ==
+          Pyxis::MapView::Result::OK);
+    CHECK(presenter.frameBuiltForCurrentEpoch());
+
+    // Rebuilding the unchanged UI model must not revoke the worker's access
+    // to requests that were released after the first render of this epoch.
+    CHECK(presenter.buildFrame(requestAt(0.0, 0.0, 3)) ==
+          Pyxis::MapView::Result::OK);
+    CHECK(presenter.frameBuiltForCurrentEpoch());
+
+    CHECK(presenter.zoomBy(1));
+    CHECK(!presenter.frameBuiltForCurrentEpoch());
+    CHECK(presenter.buildFrame(requestAt(0.0, 0.0, 4)) ==
+          Pyxis::MapView::Result::OK);
+    CHECK(presenter.frameBuiltForCurrentEpoch());
+
+    presenter.invalidateTiles();
+    CHECK(!presenter.frameBuiltForCurrentEpoch());
+    presenter.hide();
+    CHECK(!presenter.frameBuiltForCurrentEpoch());
+}
+
 void staleCompletionsRejectedAndAcceptedOnce() {
     MapScreenPresenter presenter;
     presenter.show();
@@ -285,6 +311,7 @@ void deterministicHundredThousandOperationStress() {
 
 int main() {
     fixedCapacityAndDedupe();
+    frameBuildLifecycleKeepsReleasedWorkAvailable();
     staleCompletionsRejectedAndAcceptedOnce();
     newestFrameReusesSlotsAndPurgesOldRequests();
     generationPanZoomAndRecenterBounds();