fix: invalidate native lib cache by content, not size only

plugin-build/plugin/src/main/kotlin/dev/nucleusframework/nna/plugin/codegen/FfmProxyGenerator.kt

@@ -428,7 +428,12 @@ class FfmProxyGenerator {
         appendLine("            val target = cacheDir.resolve(fileName)")
         appendLine("            stream.use { input ->")
         appendLine("                val bytes = input.readAllBytes()")
-        appendLine("                if (!Files.exists(target) || Files.size(target) != bytes.size.toLong()) {")
+        appendLine("                // Size match alone is not enough: same-size builds can carry different")
+        appendLine("                // symbols (e.g. after an API rename), so compare content before trusting the cache.")
+        appendLine("                val stale = !Files.exists(target) ||")
+        appendLine("                    Files.size(target) != bytes.size.toLong() ||")
+        appendLine("                    !Files.readAllBytes(target).contentEquals(bytes)")
+        appendLine("                if (stale) {")
         appendLine("                    val tmp = Files.createTempFile(cacheDir, name, \".tmp\")")
         appendLine("                    Files.write(tmp, bytes)")
         appendLine("                    Files.move(tmp, target, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE)")

plugin-build/plugin/src/test/kotlin/dev/nucleusframework/nna/plugin/codegen/FfmProxyGeneratorRuntimeTest.kt

@@ -0,0 +1,31 @@
+package dev.nucleusframework.nna.plugin.codegen
+
+import dev.nucleusframework.nna.plugin.ir.KneModule
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class FfmProxyGeneratorRuntimeTest {
+
+    @Test
+    fun `cache staleness check compares content, not only size`() {
+        val runtime = generateRuntime()
+
+        // A same-size library with different symbols must refresh the cache (issue #29).
+        assertTrue(
+            "Generated runtime must compare cached bytes with resource bytes",
+            runtime.contains("!Files.readAllBytes(target).contentEquals(bytes)"),
+        )
+    }
+
+    private fun generateRuntime(): String {
+        val module = KneModule(
+            libName = "demo",
+            packages = setOf("demo"),
+            classes = emptyList(),
+            dataClasses = emptyList(),
+            enums = emptyList(),
+            functions = emptyList(),
+        )
+        return FfmProxyGenerator().generate(module, "demo").getValue("KneRuntime.kt")
+    }
+}