From 304a90186ac06b77cbcc955ebbe71d9416ad297d Mon Sep 17 00:00:00 2001
From: Hy4ri <41645758+Hy4ri@users.noreply.github.com>
Date: Thu, 17 Sep 2026 14:21:38 +0000
Subject: [PATCH] Fix: Avoid eager List allocation in countDiffLineStats for
 large diffs

Replaced `diff.split("\n")` with `diff.lineSequence()` in `FileRenderers.kt`'s `countDiffLineStats()` method. This prevents massive `ArrayList` allocations on the heap when processing multi-thousand-line diffs during tool card rendering, improving memory efficiency by evaluating the lines lazily.

Added comprehensive unit tests in `FileEditSupportTest.kt` covering empty diffs, header filtering, CRLF handling, and large multi-line diffs.
---
 .../ui/chat/tool/render/FileRenderers.kt      |  2 +-
 .../chat/tool/render/FileEditSupportTest.kt   | 54 +++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 app/src/test/java/com/m57/hermescontrol/ui/chat/tool/render/FileEditSupportTest.kt

diff --git a/app/src/main/java/com/m57/hermescontrol/ui/chat/tool/render/FileRenderers.kt b/app/src/main/java/com/m57/hermescontrol/ui/chat/tool/render/FileRenderers.kt
index eb8501c2..e053079d 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/chat/tool/render/FileRenderers.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/chat/tool/render/FileRenderers.kt
@@ -79,7 +79,7 @@ internal object FileEditSupport {
         var added = 0
         var removed = 0
 
-        for (line in diff.split("\n")) {
+        for (line in diff.lineSequence()) {
             when {
                 line.startsWith("+") && !line.startsWith("+++") -> added += 1
                 line.startsWith("-") && !line.startsWith("---") -> removed += 1
diff --git a/app/src/test/java/com/m57/hermescontrol/ui/chat/tool/render/FileEditSupportTest.kt b/app/src/test/java/com/m57/hermescontrol/ui/chat/tool/render/FileEditSupportTest.kt
new file mode 100644
index 00000000..eefed8a2
--- /dev/null
+++ b/app/src/test/java/com/m57/hermescontrol/ui/chat/tool/render/FileEditSupportTest.kt
@@ -0,0 +1,54 @@
+package com.m57.hermescontrol.ui.chat.tool.render
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class FileEditSupportTest {
+    @Test
+    fun testCountDiffLineStats_emptyDiff() {
+        val stats = FileEditSupport.countDiffLineStats("")
+        assertEquals(0, stats.added)
+        assertEquals(0, stats.removed)
+    }
+
+    @Test
+    fun testCountDiffLineStats_headerFiltering() {
+        val diff =
+            """
+            --- a/file.txt
+            +++ b/file.txt
+            @@ -1,5 +1,5 @@
+             unchanged
+            -removed line
+            +added line
+            """.trimIndent()
+        val stats = FileEditSupport.countDiffLineStats(diff)
+        assertEquals(1, stats.added)
+        assertEquals(1, stats.removed)
+    }
+
+    @Test
+    fun testCountDiffLineStats_crlfHandling() {
+        val diff = "---\r\n+++\r\n+added\r\n-removed\r\n+another\r\n"
+        val stats = FileEditSupport.countDiffLineStats(diff)
+        assertEquals(2, stats.added)
+        assertEquals(1, stats.removed)
+    }
+
+    @Test
+    fun testCountDiffLineStats_largeDiff() {
+        val sb = java.lang.StringBuilder()
+        sb.append("--- a/file.txt\n")
+        sb.append("+++ b/file.txt\n")
+
+        val count = 5000
+        for (i in 0 until count) {
+            sb.append("-old line $i\n")
+            sb.append("+new line $i\n")
+        }
+
+        val stats = FileEditSupport.countDiffLineStats(sb.toString())
+        assertEquals(count, stats.added)
+        assertEquals(count, stats.removed)
+    }
+}