add response versioning support in messages for regeneration improvements

test/reasoning.test.js

@@ -77,6 +77,7 @@ test("thinking streams separately and survives reload, retry, branch and import"
     assert.equal(bot.content, "Answer");
     const retry = await api(`/chats/${chatId}/messages/${bot.id}/retry`, {});
     assert.equal(retry.message.thinking, undefined);
+    await api(`/chats/${chatId}/messages/${bot.id}/versions/0`, {});
     const branch = await api(`/chats/${chatId}/messages/${bot.id}/branch`, {confirmed: true});
     assert.equal(branch.messages.at(-1).thinking, bot.thinking);
     const exported = await api(`/exports/chats/${chatId}?format=json`);
@@ -125,6 +126,19 @@ test("thinking streams separately and survives reload, retry, branch and import"
     assert.match(roleplayWire, /event: done/);
     assert.ok(requests.at(-1).messages.some(message => message.content.includes("Guide")));
     assert.equal(requests.at(-1).think, true);
+    const roleplayMessages = (await api(`/chats/${roleplay.chat.id}/messages`)).messages;
+    for (const target of [roleplayMessages[0], roleplayMessages.at(-1)]) {
+        const retryResponse = await fetch(base + `/chats/${roleplay.chat.id}/messages/${target.id}/retry/stream`, {
+            method: "POST", headers: {"Content-Type": "application/json", Cookie: cookie},
+            body: JSON.stringify({model: "qwen3:14b", reasoning: true})
+        });
+        const retryWire = await retryResponse.text();
+        assert.match(retryWire, /event: thinking/);
+        assert.match(retryWire, /event: chunk/);
+        assert.match(retryWire, /event: done/);
+        assert.ok(requests.at(-1).messages.some(message => message.content.includes("Guide")));
+        assert.equal(requests.at(-1).think, true);
+    }
 });
 
 test("reasoning disclosure is collapsed, preserves open state and renders text safely", (t) => {