fix: expose workbench message text

internal/cloud/server-workbench-http.test.ts

@@ -92,6 +92,8 @@ test("workbench read model exposes session, messages, turn, and trace without wr
     assert.equal(messages.body.contractVersion, "workbench-message-page-v1");
     assert.equal(messages.body.messages.length, 1);
     assert.equal(messages.body.messages[0].role, "user");
+    assert.equal(messages.body.messages[0].text, "ping");
+    assert.equal(messages.body.messages[0].parts[0].text, "ping");
     assert.equal(messages.body.hasMore, true);
 
     const turn = await getJson(port, `/v1/workbench/turns/${encodeURIComponent(traceId)}`);

internal/cloud/server-workbench-http.ts

@@ -417,6 +417,7 @@ function messageFact(message, index, session, snapshot) {
     turnId: safeTurnId(message?.turnId) || traceId,
     status: normalizeStatus(message?.status ?? (isAssistantLikeRole(role) ? session.status : "completed")),
     parts,
+    text: text || "",
     textPreview: text ? text.slice(0, 240) : null,
     createdAt: textValue(message?.createdAt ?? message?.timestamp ?? message?.at) || session.startedAt || session.updatedAt || null,
     updatedAt: textValue(message?.updatedAt) || session.updatedAt || null,