diff --git a/src/resources/extensions/gsd/tests/wave5-consistency-regressions.test.ts b/src/resources/extensions/gsd/tests/wave5-consistency-regressions.test.ts
new file mode 100644
index 000000000..15c64b6cf
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/wave5-consistency-regressions.test.ts
@@ -0,0 +1,107 @@
+// GSD State Machine — Wave 5 Consistency Regression Tests
+// Validates isClosedStatus usage in projections, upsertDecision seq preservation,
+// and event schema versioning.
+
+import { describe, test } from "node:test";
+import assert from "node:assert/strict";
+import { mkdtempSync, rmSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { isClosedStatus } from "../status-guards.js";
+import { openDatabase, closeDatabase, upsertDecision, _getAdapter } from "../gsd-db.js";
+
+// ── Fix 19: isClosedStatus covers all closed statuses ──
+
+describe("isClosedStatus used by projections", () => {
+  test("skipped is closed (projections now show checked)", () => {
+    assert.ok(isClosedStatus("skipped"));
+  });
+  test("complete is closed", () => {
+    assert.ok(isClosedStatus("complete"));
+  });
+  test("done is closed", () => {
+    assert.ok(isClosedStatus("done"));
+  });
+  test("in-progress is not closed", () => {
+    assert.ok(!isClosedStatus("in-progress"));
+  });
+});
+
+// ── Fix 20: upsertDecision preserves seq on update ──
+
+describe("upsertDecision preserves seq column", () => {
+  test("seq is preserved when decision is re-upserted", () => {
+    const tmp = mkdtempSync(join(tmpdir(), "gsd-upsert-test-"));
+    const dbPath = join(tmp, "gsd.db");
+    try {
+      openDatabase(dbPath);
+      const adapter = _getAdapter();
+      assert.ok(adapter, "adapter must be available");
+
+      // Insert two decisions
+      upsertDecision({
+        id: "D001", when_context: "ctx1", scope: "s1",
+        decision: "d1", choice: "c1", rationale: "r1",
+        revisable: "yes", made_by: "agent", superseded_by: null,
+      });
+      upsertDecision({
+        id: "D002", when_context: "ctx2", scope: "s2",
+        decision: "d2", choice: "c2", rationale: "r2",
+        revisable: "yes", made_by: "agent", superseded_by: null,
+      });
+
+      // Get original seq values
+      const rows1 = adapter.prepare("SELECT id, seq FROM decisions ORDER BY seq").all() as Array<{ id: string; seq: number }>;
+      assert.strictEqual(rows1[0].id, "D001");
+      assert.strictEqual(rows1[1].id, "D002");
+      const d001OriginalSeq = rows1[0].seq;
+
+      // Re-upsert D001 with updated content
+      upsertDecision({
+        id: "D001", when_context: "updated", scope: "s1",
+        decision: "d1-updated", choice: "c1", rationale: "r1",
+        revisable: "yes", made_by: "agent", superseded_by: null,
+      });
+
+      // Verify seq is preserved (not moved to end)
+      const rows2 = adapter.prepare("SELECT id, seq FROM decisions ORDER BY seq").all() as Array<{ id: string; seq: number }>;
+      assert.strictEqual(rows2[0].id, "D001", "D001 should still be first by seq");
+      assert.strictEqual(rows2[0].seq, d001OriginalSeq, "D001 seq should be preserved");
+      assert.strictEqual(rows2[1].id, "D002", "D002 should still be second");
+
+      // Verify content was updated
+      const updated = adapter.prepare("SELECT decision FROM decisions WHERE id = 'D001'").get() as { decision: string };
+      assert.strictEqual(updated.decision, "d1-updated");
+
+      closeDatabase();
+    } finally {
+      rmSync(tmp, { recursive: true, force: true });
+    }
+  });
+});
+
+// ── Fix 23: Event schema versioning ──
+
+describe("WorkflowEvent v field", () => {
+  test("appendEvent includes v:2 in output", async () => {
+    const tmp = mkdtempSync(join(tmpdir(), "gsd-event-v-test-"));
+    try {
+      const { appendEvent } = await import("../workflow-events.js");
+      appendEvent(tmp, {
+        cmd: "test-event",
+        params: { foo: "bar" },
+        ts: new Date().toISOString(),
+        actor: "system",
+      });
+
+      const { readFileSync } = await import("node:fs");
+      const logPath = join(tmp, ".gsd", "event-log.jsonl");
+      const line = readFileSync(logPath, "utf-8").trim();
+      const event = JSON.parse(line);
+      assert.strictEqual(event.v, 2, "New events should have v:2");
+      assert.strictEqual(event.cmd, "test-event");
+    } finally {
+      rmSync(tmp, { recursive: true, force: true });
+    }
+  });
+});