Refresh native Git helper aliases after app upgrade

- Rebuild the app-private git-exec helper directory when the packaged native Git binary changes.
- Remove stale helper aliases before recreating symlinks/copies.
- Add regression coverage for refreshing cached Git exec aliases across binary changes.

app/build.gradle.kts

@@ -19,8 +19,8 @@ android {
         applicationId = "solutions.tretter.githugandroid"
         minSdk = 26
         targetSdk = 35
-        versionCode = 136
-        versionName = "0.1.135"
+        versionCode = 137
+        versionName = "0.1.136"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true

app/src/main/java/solutions/tretter/githugandroid/GitRuntime.kt

@@ -852,6 +852,7 @@ class GitRepositoryRuntime private constructor(
         } else {
             File(binary.parentFile ?: binary.absoluteFile.parentFile ?: sandboxesRoot, "git-exec")
         }
+        refreshGitExecDirectoryIfNeeded(directory, binary)
         directory.mkdirs()
 
         File(directory, "git").also { alias ->
@@ -870,7 +871,27 @@ class GitRepositoryRuntime private constructor(
         return directory
     }
 
+    private fun refreshGitExecDirectoryIfNeeded(directory: File, binary: File) {
+        val fingerprint = buildString {
+            append(binary.absolutePath)
+            append('\n')
+            append(binary.length())
+            append('\n')
+            append(binary.lastModified())
+        }
+        val stamp = File(directory, ".binary-fingerprint")
+        val previousFingerprint = stamp.takeIf { it.isFile }?.readText()
+        if (previousFingerprint != fingerprint) {
+            directory.deleteRecursively()
+        }
+        directory.mkdirs()
+        stamp.writeText(fingerprint)
+    }
+
     private fun createGitAlias(binary: File, alias: File) {
+        if (alias.exists() || Files.isSymbolicLink(alias.toPath())) {
+            alias.delete()
+        }
         if (context != null) {
             try {
                 Os.symlink(binary.absolutePath, alias.absolutePath)

app/src/test/java/solutions/tretter/githugandroid/GitSandboxEngineTest.kt

@@ -185,6 +185,37 @@ class GitSandboxEngineTest {
         }
     }
 
+    @Test
+    fun nativeGitExecAliasesRefreshWhenBinaryChanges() {
+        val git = testGitBinary()
+        assumeTrue(git.exists() && git.canExecute())
+        val root = Files.createTempDirectory("githug-exec-refresh").toFile()
+        try {
+            val firstGit = File(root, "first-git").also { git.copyTo(it); it.setExecutable(true) }
+            val secondGit = File(root, "second-git").also { git.copyTo(it); it.setExecutable(true) }
+            val level = level(
+                id = "exec-refresh-test",
+                title = "Exec Refresh Test",
+                description = "",
+                hints = emptyList(),
+                commandSuggestions = emptyList(),
+                setup = { RepoState(initialized = true) },
+                validator = { _, _ -> false },
+            )
+
+            GitRepositoryRuntime(root, firstGit).prepareLevel(level)
+            val alias = File(root, "git-exec/git")
+            assertTrue(alias.exists())
+            assertTrue(File(root, "git-exec/.binary-fingerprint").readText().contains(firstGit.absolutePath))
+
+            GitRepositoryRuntime(root, secondGit).prepareLevel(level)
+            assertTrue(alias.exists())
+            assertTrue(File(root, "git-exec/.binary-fingerprint").readText().contains(secondGit.absolutePath))
+        } finally {
+            root.deleteRecursively()
+        }
+    }
+
     @Test
     fun nativePushLevelHasDivergedStatusAndRebasesCleanly() {
         val git = testGitBinary()