diff --git a/src/test/java/com/taskflow/model/ProjectTest.java b/src/test/java/com/taskflow/model/ProjectTest.java
new file mode 100644
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--- /dev/null
+++ b/src/test/java/com/taskflow/model/ProjectTest.java
@@ -0,0 +1,126 @@
+package com.taskflow.model;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * Bug-pin tests for Project model methods.
+ *
+ * Tests marked with a BUG comment document currently broken behaviour.
+ * They should be updated (and the underlying issue fixed) when the bug
+ * is resolved.
+ */
+class ProjectTest {
+
+    // -----------------------------------------------------------------------
+    // getProgress() – division by zero when taskCount == 0
+    // -----------------------------------------------------------------------
+
+    /**
+     * BUG: getProgress() divides by taskCount without guarding against zero,
+     * producing NaN.  Related to Bug #3 / Issue #3.
+     */
+    @Test
+    void getProgress_withZeroTasks_returnsNaN() {
+        Project project = new Project("Demo", "DEMO");
+        // taskCount and completedTaskCount both default to 0
+        double progress = project.getProgress();
+        // BUG: should return 0.0 but returns NaN (0.0 / 0 = NaN)
+        assertTrue(Double.isNaN(progress),
+                "BUG: getProgress() should guard against taskCount == 0 but currently returns NaN");
+    }
+
+    @Test
+    void getProgress_withNonZeroTasks_returnsCorrectPercentage() {
+        Project project = new Project("Demo", "DEMO");
+        project.setTaskCount(10);
+        project.setCompletedTaskCount(5);
+        assertEquals(50.0, project.getProgress(), 0.001);
+    }
+
+    @Test
+    void getProgress_withAllTasksCompleted_returns100() {
+        Project project = new Project("Demo", "DEMO");
+        project.setTaskCount(4);
+        project.setCompletedTaskCount(4);
+        assertEquals(100.0, project.getProgress(), 0.001);
+    }
+
+    @Test
+    void getProgress_withNoCompletedTasks_returns0() {
+        Project project = new Project("Demo", "DEMO");
+        project.setTaskCount(8);
+        project.setCompletedTaskCount(0);
+        assertEquals(0.0, project.getProgress(), 0.001);
+    }
+
+    // -----------------------------------------------------------------------
+    // getMemberIds() – NPE on null members, NumberFormatException on bad data
+    // -----------------------------------------------------------------------
+
+    @Test
+    void getMemberIds_withValidMembers_returnsParsedIds() {
+        Project project = new Project("Demo", "DEMO");
+        project.setMembers("1,5,12,23");
+        List<Long> ids = project.getMemberIds();
+        assertEquals(4, ids.size());
+        assertEquals(1L, ids.get(0));
+        assertEquals(5L, ids.get(1));
+        assertEquals(12L, ids.get(2));
+        assertEquals(23L, ids.get(3));
+    }
+
+    @Test
+    void getMemberIds_withSingleMember_returnsSingleId() {
+        Project project = new Project("Demo", "DEMO");
+        project.setMembers("42");
+        List<Long> ids = project.getMemberIds();
+        assertEquals(1, ids.size());
+        assertEquals(42L, ids.get(0));
+    }
+
+    /**
+     * BUG: getMemberIds() calls members.split(",") without a null-check,
+     * throwing NullPointerException when members has never been set.
+     */
+    @Test
+    void getMemberIds_withNullMembers_throwsNullPointerException() {
+        Project project = new Project("Demo", "DEMO");
+        // members field is null (constructor does not initialise it)
+        assertThrows(NullPointerException.class, project::getMemberIds,
+                "BUG: getMemberIds() should handle null members gracefully but throws NPE");
+    }
+
+    /**
+     * Java's String.split(",") with default limit drops trailing empty tokens,
+     * so a trailing comma is silently tolerated — the caller may not notice
+     * the missing empty entry.  This test documents the actual (safe) behaviour.
+     */
+    @Test
+    void getMemberIds_withTrailingComma_parsesSuccessfully() {
+        Project project = new Project("Demo", "DEMO");
+        project.setMembers("1,2,3,");
+        // String.split(",") with limit=0 strips the trailing empty token —
+        // the result is [1, 2, 3], same as without the trailing comma.
+        List<Long> ids = project.getMemberIds();
+        assertEquals(3, ids.size());
+        assertEquals(1L, ids.get(0));
+        assertEquals(2L, ids.get(1));
+        assertEquals(3L, ids.get(2));
+    }
+
+    /**
+     * BUG: getMemberIds() does not trim whitespace before calling
+     * Long.parseLong(), causing NumberFormatException on "1, 2, 3".
+     */
+    @Test
+    void getMemberIds_withWhitespacePaddedIds_throwsNumberFormatException() {
+        Project project = new Project("Demo", "DEMO");
+        project.setMembers("1, 2, 3");
+        assertThrows(NumberFormatException.class, project::getMemberIds,
+                "BUG: getMemberIds() should trim whitespace before parsing but throws NumberFormatException");
+    }
+}