[TS PBT] Save campaign artifacts before stdout publication

usvm-ts-fast-check/src/main/kotlin/org/usvm/ts/pbt/cli/CampaignFileRequest.kt

@@ -55,8 +55,11 @@ internal fun runCampaignFile(
     )
 
     val json = PropertyManifestJson.json.encodeToUtf8SafeString(artifact)
-    output.appendLine(json)
-    Files.writeString(Path.of(args[1]), json)
+    try {
+        Files.writeString(Path.of(args[1]), json)
+    } finally {
+        output.appendLine(json)
+    }
 
     campaignExitCode(artifact.result)
 } catch (error: IllegalArgumentException) {

usvm-ts-fast-check/src/test/kotlin/org/usvm/ts/pbt/cli/CampaignFileCliTest.kt

@@ -1,5 +1,6 @@
 package org.usvm.ts.pbt.cli
 
+import kotlinx.serialization.decodeFromString
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.io.TempDir
 import org.usvm.ts.pbt.backend.PropertyRunConfiguration
@@ -13,6 +14,8 @@ import org.usvm.ts.pbt.model.PropertyInput
 import org.usvm.ts.pbt.model.TypeScriptEntryPoint
 import org.usvm.ts.pbt.model.encodeToUtf8SafeString
 import org.usvm.ts.pbt.testResourcesRoot
+import java.io.IOException
+import java.io.Writer
 import java.nio.file.Files
 import java.nio.file.Path
 import kotlin.test.assertEquals
@@ -61,6 +64,57 @@ class CampaignFileCliTest {
         assertFalse(Files.exists(destination))
     }
 
+    @Test
+    fun `file artifact is readable before failing stdout publication`() {
+        val request = request(mode = PropertyCampaignMode.PBT_ONLY)
+        val path = directory.resolve("request.json")
+        val destination = directory.resolve("artifact.json")
+        Files.writeString(path, PropertyManifestJson.json.encodeToUtf8SafeString(request))
+        val errors = StringBuilder()
+        var stdoutAttempted = false
+        val output = object : Writer() {
+            override fun write(buffer: CharArray, offset: Int, length: Int) {
+                stdoutAttempted = true
+                val artifact = PropertyCampaignArtifact.read(destination)
+                assertEquals(PropertyCampaignMode.PBT_ONLY, artifact.result.mode)
+
+                throw IOException("stdout closed")
+            }
+
+            override fun flush() = Unit
+
+            override fun close() = Unit
+        }
+
+        val exit = runCampaignFile(arrayOf(path.toString(), destination.toString()), output, errors)
+        val artifact = PropertyCampaignArtifact.read(destination)
+
+        assertEquals(2, exit)
+        assertTrue(stdoutAttempted)
+        assertTrue(errors.contains("stdout closed"))
+        assertEquals(1, artifact.result.concrete?.numRuns)
+        assertEquals(37, artifact.configuration.seed)
+    }
+
+    @Test
+    fun `file write failure retains the full stdout artifact and original error`() {
+        val request = request(mode = PropertyCampaignMode.PBT_ONLY)
+        val path = directory.resolve("request.json")
+        val destination = directory.resolve("missing-parent").resolve("artifact.json")
+        Files.writeString(path, PropertyManifestJson.json.encodeToUtf8SafeString(request))
+        val output = StringBuilder()
+        val errors = StringBuilder()
+
+        val exit = runCampaignFile(arrayOf(path.toString(), destination.toString()), output, errors)
+        val artifact = PropertyManifestJson.json.decodeFromString<PropertyCampaignArtifact>(output.toString())
+
+        assertEquals(2, exit)
+        assertEquals(destination.toString(), errors.toString().trim())
+        assertFalse(Files.exists(destination))
+        assertEquals(1, artifact.result.concrete?.numRuns)
+        assertEquals(37, artifact.configuration.seed)
+    }
+
     private fun request(mode: PropertyCampaignMode) = CampaignFileRequest(
         sourceRoot = testResourcesRoot().resolve("properties/campaign").toString(),
         property = PropertyDefinition(