test: add Gson parsing tests for job list models

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

app/src/test/java/com/example/resbuilder/JobListModelsTest.kt

@@ -0,0 +1,81 @@
+package com.example.resbuilder
+
+import com.example.resbuilder.data.model.JobListResponse
+import com.example.resbuilder.data.model.JobSummary
+import com.google.gson.Gson
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Tests for the API response models introduced with the "My Resumes" feature.
+ *
+ * These verify the exact wire format expected from `GET /jobs` so that a backend
+ * contract change fails loudly here rather than silently breaking the UI.
+ */
+class JobListModelsTest {
+
+    private val gson = Gson()
+
+    @Test
+    fun `parses a completed resume job from the backend shape`() {
+        val json = """
+            {
+              "jobs": [
+                {
+                  "job_id": "abc-123",
+                  "type": "resume",
+                  "status": "completed",
+                  "title": "Senior Android Engineer",
+                  "created_at": "2026-08-04T12:00:00Z"
+                }
+              ]
+            }
+        """.trimIndent()
+
+        val parsed = gson.fromJson(json, JobListResponse::class.java)
+
+        assertEquals(1, parsed.jobs.size)
+        val job = parsed.jobs[0]
+        assertEquals("abc-123", job.job_id)
+        assertEquals("resume", job.type)
+        assertEquals("completed", job.status)
+        assertEquals("Senior Android Engineer", job.title)
+        assertEquals("2026-08-04T12:00:00Z", job.created_at)
+    }
+
+    @Test
+    fun `title is null when backend omits it`() {
+        val json = """
+            {"jobs": [{"job_id": "x", "type": "cover_letter", "status": "queued"}]}
+        """.trimIndent()
+
+        val parsed = gson.fromJson(json, JobListResponse::class.java)
+        val job = parsed.jobs[0]
+
+        assertNull(job.title)
+        assertNull(job.created_at)
+        assertEquals("cover_letter", job.type)
+    }
+
+    @Test
+    fun `empty jobs list parses to empty collection`() {
+        val json = """{"jobs": []}"""
+
+        val parsed = gson.fromJson(json, JobListResponse::class.java)
+
+        assertTrue(parsed.jobs.isEmpty())
+    }
+
+    @Test
+    fun `JobSummary fields are immutable`() {
+        val job = JobSummary(job_id = "id", type = "resume", status = "completed")
+
+        // Reflectively assert all fields are val (final). This guards against
+        // regressions that would make the model mutable and thread-unsafe.
+        for (field in JobSummary::class.java.declaredFields) {
+            assertEquals("Field ${field.name} must be final", java.lang.reflect.Modifier.FINAL, field.modifiers and java.lang.reflect.Modifier.FINAL)
+        }
+    }
+}