fix(gui): resolve session slowdown and hang under sustained compare load

A long GUI session could degrade until the app needed to be force-quit. Root cause was runaway /progress polling on the Webpage and Document compare pages: if a compare response was ever lost, the 200ms poller fired indefinitely and saturated the bridge's 16-thread worker pool, 503-ing every request including /cancel.

- Cap progress polling on WebpageComparePage and DocumentComparePage (progressPollMax ~5min); on timeout, cancel the wedged compare on the bridge and recover the UI. Mirror the same cancel-on-timeout in Main.qml's progress cap.

- Bound log file growth: rotate linsync.log to a single .1 backup past 8 MiB at startup (logging.rs).

- Release the global bridge state lock during /save file I/O via a three-phase prepare/perform/finish split, with a re-lock race guard so a concurrent edit is never silently marked saved.

- Keep /cancel and /progress servicable under saturation: route them before the worker-cap check (spawn-first, request-line routing) so the UI can always recover an in-flight compare.

- Bump workspace version to 1.16.3 and sync packaging recipes, changelogs, and metainfo.

Author: visorcraft

Cargo.lock

@@ -9,7 +9,7 @@ members = [
 resolver = "3"
 
 [workspace.package]
-version = "1.16.2"
+version = "1.16.3"
 edition = "2024"
 license = "GPL-3.0-only"
 repository = "https://github.com/visorcraft/LinSync"

Cargo.toml

@@ -47,6 +47,13 @@ Controls.Pane {
     property int progressCurrent: 0
     property int progressTotal: 0
     property string progressMessage: ""
+    // Defensive iteration cap for the progress timer so a compare whose XHR
+    // never completes (bridge worker wedged, OCR plugin hang, lost response)
+    // cannot poll /progress forever and saturate the bridge connection pool.
+    // At 200 ms intervals, 1500 iterations == 5 minutes. Mirrors Main.qml's
+    // progressPollMax safety net.
+    property int progressPollCount: 0
+    readonly property int progressPollMax: 1500
     property int selectedRenderedPageIndex: -1
     readonly property bool isRenderedMode: modeCombo.currentText === "Rendered"
     property real renderedZoom: 1.0
@@ -98,6 +105,7 @@ Controls.Pane {
         root.progressCurrent = 0;
         root.progressTotal = 0;
         root.progressMessage = "";
+        root.progressPollCount = 0;
 
         const modeStr = {
             "OCR Text": "ocr_text",
@@ -142,6 +150,23 @@ Controls.Pane {
         repeat: true
         running: root.running && root.activeRequestId !== ""
         onTriggered: {
+            if (!root.running || root.activeRequestId === "") {
+                progressTimer.stop()
+                return
+            }
+            // If the compare XHR never reports back, stop polling, cancel the
+            // request on the bridge (so its worker slot is freed), and recover
+            // the UI instead of polling forever and exhausting the connection
+            // pool — the "app gets slow until restarted" failure mode.
+            root.progressPollCount += 1
+            if (root.progressPollCount > root.progressPollMax) {
+                root.bridgeGet("/cancel?id=" + encodeURIComponent(root.activeRequestId), function () {})
+                root.running = false
+                root.activeRequestId = ""
+                root.statusText = qsTr("Compare timed out — no response from the bridge")
+                progressTimer.stop()
+                return
+            }
             root.bridgeGet("/progress?id=" + encodeURIComponent(root.activeRequestId), function (ok, data) {
                 if (!ok || !data)
                     return;

apps/linsync-gui/qml/DocumentComparePage.qml

@@ -6825,6 +6825,14 @@ Kirigami.ApplicationWindow {
             }
             root.progressPollCount += 1
             if (root.progressPollCount > root.progressPollMax) {
+                // Compare never reported back. Cancel it on the bridge so its
+                // worker slot is freed (cooperative cancel — polled by the
+                // folder/text/image compare loops), then recover the UI
+                // instead of polling forever and exhausting the connection
+                // pool — the "app gets slow until restarted" failure mode.
+                var hungId = root.activeRequestId
+                if (hungId && root.bridgeUrl)
+                    root.bridgeGet("/cancel?id=" + encodeURIComponent(hungId), function () {})
                 root.comparing = false
                 root.activeRequestId = ""
                 root.statusText = qsTr("Compare monitoring timed out")

apps/linsync-gui/qml/Main.qml

@@ -65,6 +65,13 @@ Controls.Pane {
     property int progressTotal: 0
     property string progressMessage: ""
     property bool pendingNewTab: false
+    // Defensive iteration cap for the progress timer so a compare whose XHR
+    // never completes (bridge worker wedged, plugin hang, lost response)
+    // cannot poll /progress forever and saturate the bridge connection pool.
+    // At 200 ms intervals, 1500 iterations == 5 minutes. Mirrors Main.qml's
+    // progressPollMax safety net.
+    property int progressPollCount: 0
+    readonly property int progressPollMax: 1500
 
     // Per-row diff tints over the page background (left=red, right=green,
     // changed=amber); "equal" rows are absent → transparent.
@@ -131,6 +138,7 @@ Controls.Pane {
         root.progressCurrent = 0;
         root.progressTotal = 0;
         root.progressMessage = "";
+        root.progressPollCount = 0;
         const left = encodeURIComponent(root.leftUrl);
         const right = encodeURIComponent(root.rightUrl);
         const mode = encodeURIComponent(root.subMode);
@@ -196,6 +204,25 @@ Controls.Pane {
         repeat: true
         running: root.busy && root.activeRequestId !== ""
         onTriggered: {
+            if (!root.busy || root.activeRequestId === "") {
+                progressTimer.stop()
+                return
+            }
+            // If the compare XHR never reports back, stop polling, cancel the
+            // request on the bridge (so its worker slot is freed), and recover
+            // the UI instead of polling forever and exhausting the connection
+            // pool — the "app gets slow until restarted" failure mode.
+            root.progressPollCount += 1
+            if (root.progressPollCount > root.progressPollMax) {
+                root.bridgeGet("/cancel?id=" + encodeURIComponent(root.activeRequestId), function () {})
+                root.busy = false
+                root.activeRequestId = ""
+                root.pendingNewTab = false
+                root.resultError = true
+                root.resultSummary = qsTr("Compare timed out — no response from the bridge")
+                progressTimer.stop()
+                return
+            }
             root.bridgeGet("/progress?id=" + encodeURIComponent(root.activeRequestId), function (ok, data) {
                 if (!ok || !data)
                     return;