From 9f99a7bc0b5482ec1e1b70376d44c3df963ffec2 Mon Sep 17 00:00:00 2001
From: Kyle Carberry <kyle@coder.com>
Date: Fri, 15 May 2026 09:33:54 -0400
Subject: [PATCH] fix(coderd): stabilize TestPatchChatMessage/ChangesModel
 flaky test (#25306)

Fixes coder/internal#1535

## Problem

`TestPatchChatMessage/ChangesModel` is flaky because it races with the
chat daemon's background processing.

`CreateChat` sets the chat to `pending` and the daemon picks it up
asynchronously. The test immediately calls `EditChatMessage` (which
changes the model to an override) while the first processing round is
still running. The `InsertChatMessages` SQL CTE unconditionally updates
`chats.last_model_config_id` to the model of the last inserted message.
When the daemon's in-flight message insertions commit after the edit
transaction, they overwrite `last_model_config_id` back to the default
model.

Similarly, after the edit sets the chat back to `pending`, the daemon
re-processes it. The test's `GetChat` call could race with this second
round.

## Fix

Poll for the chat to reach `waiting` (or `error`) status:
1. **Before editing**: wait for the initial processing round to complete
2. **After editing**: wait for the second processing round (triggered by
the edit) to complete

Then assert `last_model_config_id`, which is now stable.

> Generated with [Coder Agents](https://coder.com/agents) by @kylecarbs
---
 coderd/exp_chats_test.go | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/coderd/exp_chats_test.go b/coderd/exp_chats_test.go
index 61720a426c..77ad68acb6 100644
--- a/coderd/exp_chats_test.go
+++ b/coderd/exp_chats_test.go
@@ -7792,6 +7792,20 @@ func TestPatchChatMessage(t *testing.T) {
 		require.Equal(t, defaultModel.ID, chat.LastModelConfigID,
 			"chat starts on the default model")
 
+		// Wait for the initial chat processing to complete before
+		// editing. CreateChat sets the chat to pending and the daemon
+		// processes it asynchronously; editing while that first round
+		// is still running can race with message insertions that
+		// overwrite last_model_config_id.
+		testutil.Eventually(ctx, t, func(ctx context.Context) bool {
+			c, getErr := client.GetChat(ctx, chat.ID)
+			if getErr != nil {
+				return false
+			}
+			return c.Status != codersdk.ChatStatusPending &&
+				c.Status != codersdk.ChatStatusRunning
+		}, testutil.IntervalFast, "initial chat processing did not finish")
+
 		messagesResult, err := client.GetChatMessages(ctx, chat.ID, nil)
 		require.NoError(t, err)
 		var userMessageID int64
@@ -7816,6 +7830,19 @@ func TestPatchChatMessage(t *testing.T) {
 		require.Equal(t, overrideModel.ID, *edited.Message.ModelConfigID,
 			"replacement message must use the requested model")
 
+		// Wait for the second round of processing (triggered by the
+		// edit) to complete, then verify last_model_config_id.
+		// Reading immediately after EditChatMessage can race with the
+		// daemon re-processing the now-pending chat.
+		testutil.Eventually(ctx, t, func(ctx context.Context) bool {
+			c, getErr := client.GetChat(ctx, chat.ID)
+			if getErr != nil {
+				return false
+			}
+			return c.Status != codersdk.ChatStatusPending &&
+				c.Status != codersdk.ChatStatusRunning
+		}, testutil.IntervalFast, "post-edit chat processing did not finish")
+
 		updatedChat, err := client.GetChat(ctx, chat.ID)
 		require.NoError(t, err)
 		require.Equal(t, overrideModel.ID, updatedChat.LastModelConfigID,