diff --git a/scaletest/chat/provider.go b/scaletest/chat/provider.go
index cea691e5a3..8ff35f4322 100644
--- a/scaletest/chat/provider.go
+++ b/scaletest/chat/provider.go
@@ -12,6 +12,7 @@ import (
 
 	"cdr.dev/slog/v3"
 	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/scaletest/llmmock"
 	"github.com/coder/retry"
 )
 
@@ -23,7 +24,7 @@ const (
 	scaletestModelName             = "scaletest-model"
 	scaletestModelDisplayName      = "Scaletest Model"
 	scaletestModelContextLimit     = int64(4096)
-	scaletestAIProviderProbePath   = "/api/v2/aibridge/" + scaletestAIProviderName + "/v1/chat/completions"
+	scaletestAIProviderProbePath   = "/api/v2/aibridge/" + scaletestAIProviderName + "/v1/models"
 	scaletestAIProviderProbeWait   = 15 * time.Second
 	scaletestAIProviderProbePeriod = 100 * time.Millisecond
 )
@@ -67,7 +68,7 @@ func EnsureScaletestModelConfig(ctx context.Context, client *codersdk.Client, lo
 	}
 
 	if providerAction != scaletestAIProviderActionReused {
-		if err := waitForScaletestAIProviderRoute(ctx, client, logger); err != nil {
+		if err := waitForScaletestAIProviderRoute(ctx, client, logger, llmMockURL); err != nil {
 			return uuid.Nil, xerrors.Errorf("wait for mock LLM provider reload: %w", err)
 		}
 	}
@@ -75,7 +76,7 @@ func EnsureScaletestModelConfig(ctx context.Context, client *codersdk.Client, lo
 	return ensureScaletestChatModelConfig(ctx, codersdk.NewExperimentalClient(client), logger, provider)
 }
 
-func waitForScaletestAIProviderRoute(ctx context.Context, client *codersdk.Client, logger slog.Logger) error {
+func waitForScaletestAIProviderRoute(ctx context.Context, client *codersdk.Client, logger slog.Logger, llmMockURL string) error {
 	deploymentConfig, err := client.DeploymentConfig(ctx)
 	if err != nil {
 		return xerrors.Errorf("get deployment config: %w", err)
@@ -86,38 +87,39 @@ func waitForScaletestAIProviderRoute(ctx context.Context, client *codersdk.Clien
 		return nil
 	}
 
+	expectedMarker, err := llmmock.ProbeMarkerForBaseURL(llmMockURL)
+	if err != nil {
+		return xerrors.Errorf("build mock LLM provider probe marker: %w", err)
+	}
+
 	logger.Info(ctx, "waiting for mock LLM provider reload", slog.F("provider_name", scaletestAIProviderName))
 	ctx, cancel := context.WithTimeout(ctx, scaletestAIProviderProbeWait)
 	defer cancel()
 
+	var lastStatus int
+	var lastBody string
 	for retrier := retry.New(scaletestAIProviderProbePeriod, scaletestAIProviderProbePeriod); retrier.Wait(ctx); {
-		res, err := client.Request(ctx, http.MethodPost, scaletestAIProviderProbePath, map[string]any{
-			"model": scaletestModelName,
-			"messages": []map[string]string{{
-				"role":    "user",
-				"content": "ping",
-			}},
-			"stream": false,
-		}, func(r *http.Request) {
+		res, err := client.Request(ctx, http.MethodGet, scaletestAIProviderProbePath, nil, func(r *http.Request) {
 			r.Header.Set("Authorization", "Bearer "+client.SessionToken())
 		})
 		if err != nil {
-			return err
+			return xerrors.Errorf("probe mock LLM provider route: %w", err)
 		}
 		body, err := io.ReadAll(io.LimitReader(res.Body, 4096))
 		_ = res.Body.Close()
 		if err != nil {
 			return xerrors.Errorf("read probe response: %w", err)
 		}
-		if res.StatusCode == http.StatusOK {
+		lastStatus = res.StatusCode
+		lastBody = strings.TrimSpace(string(body))
+		if res.StatusCode == http.StatusOK && strings.Contains(lastBody, expectedMarker) {
 			return nil
 		}
-		if res.StatusCode != http.StatusNotFound || !strings.Contains(string(body), "route not supported") {
-			return xerrors.Errorf("status %d: %s", res.StatusCode, strings.TrimSpace(string(body)))
-		}
-		logger.Debug(ctx, "mock LLM provider route is not ready")
+		logger.Debug(ctx, "mock LLM provider route is not ready",
+			slog.F("status_code", res.StatusCode),
+		)
 	}
-	return xerrors.Errorf("timed out waiting for mock LLM provider route")
+	return xerrors.Errorf("timed out waiting for mock LLM provider route to report marker %q (last status %d: %s)", expectedMarker, lastStatus, lastBody)
 }
 
 func ensureScaletestChatModelConfig(ctx context.Context, client *codersdk.ExperimentalClient, logger slog.Logger, provider codersdk.AIProvider) (uuid.UUID, error) {
diff --git a/scaletest/chat/provider_internal_test.go b/scaletest/chat/provider_internal_test.go
new file mode 100644
index 0000000000..765124b82a
--- /dev/null
+++ b/scaletest/chat/provider_internal_test.go
@@ -0,0 +1,192 @@
+package chat
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"sync/atomic"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/scaletest/llmmock"
+)
+
+func TestEnsureScaletestChatModelConfig(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	providerID := uuid.MustParse("44444444-4444-4444-4444-444444444444")
+	wrongProviderID := uuid.MustParse("55555555-5555-5555-5555-555555555555")
+	matchingConfigID := uuid.MustParse("66666666-6666-6666-6666-666666666666")
+	createdConfigID := uuid.MustParse("77777777-7777-7777-7777-777777777777")
+	provider := codersdk.AIProvider{ID: providerID}
+
+	t.Run("ReusesMatchingProviderAndModel", func(t *testing.T) {
+		t.Parallel()
+
+		client := codersdk.NewExperimentalClient(newProviderTestClient(t, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.Method == http.MethodGet && r.URL.Path == "/api/experimental/chats/model-configs":
+				writeJSON(t, rw, http.StatusOK, []codersdk.ChatModelConfig{
+					{
+						ID:           uuid.MustParse("88888888-8888-8888-8888-888888888888"),
+						AIProviderID: &wrongProviderID,
+						Model:        scaletestModelName,
+						Enabled:      true,
+					},
+					{
+						ID:           matchingConfigID,
+						AIProviderID: &providerID,
+						Model:        scaletestModelName,
+						Enabled:      true,
+					},
+				})
+			default:
+				t.Fatalf("unexpected request %s %s", r.Method, r.URL.Path)
+			}
+		})))
+
+		gotID, err := ensureScaletestChatModelConfig(ctx, client, testLogger(), provider)
+		require.NoError(t, err)
+		require.Equal(t, matchingConfigID, gotID)
+	})
+
+	t.Run("CreatesWhenNoConfigMatches", func(t *testing.T) {
+		t.Parallel()
+
+		var createReq codersdk.CreateChatModelConfigRequest
+		client := codersdk.NewExperimentalClient(newProviderTestClient(t, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.Method == http.MethodGet && r.URL.Path == "/api/experimental/chats/model-configs":
+				writeJSON(t, rw, http.StatusOK, []codersdk.ChatModelConfig{})
+			case r.Method == http.MethodPost && r.URL.Path == "/api/experimental/chats/model-configs":
+				require.NoError(t, json.NewDecoder(r.Body).Decode(&createReq))
+				writeJSON(t, rw, http.StatusCreated, codersdk.ChatModelConfig{
+					ID:           createdConfigID,
+					AIProviderID: &providerID,
+					Model:        scaletestModelName,
+					Enabled:      true,
+				})
+			default:
+				t.Fatalf("unexpected request %s %s", r.Method, r.URL.Path)
+			}
+		})))
+
+		gotID, err := ensureScaletestChatModelConfig(ctx, client, testLogger(), provider)
+		require.NoError(t, err)
+		require.Equal(t, createdConfigID, gotID)
+		require.Equal(t, &providerID, createReq.AIProviderID)
+		require.Equal(t, scaletestModelName, createReq.Model)
+		require.Equal(t, scaletestModelDisplayName, createReq.DisplayName)
+		require.NotNil(t, createReq.Enabled)
+		require.True(t, *createReq.Enabled)
+		require.NotNil(t, createReq.IsDefault)
+		require.False(t, *createReq.IsDefault)
+		require.NotNil(t, createReq.ContextLimit)
+		require.Equal(t, scaletestModelContextLimit, *createReq.ContextLimit)
+	})
+}
+
+func TestWaitForScaletestAIProviderRoute(t *testing.T) {
+	t.Parallel()
+
+	llmMockURL := "http://new.example.test/v1"
+	expectedMarker, err := llmmock.ProbeMarkerForBaseURL(llmMockURL)
+	require.NoError(t, err)
+
+	t.Run("WaitsUntilExpectedMarker", func(t *testing.T) {
+		t.Parallel()
+
+		var probeCount atomic.Int64
+		client := newProviderTestClient(t, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.Method == http.MethodGet && r.URL.Path == "/api/v2/deployment/config":
+				writeDeploymentConfig(t, rw, true)
+			case r.Method == http.MethodGet && r.URL.Path == scaletestAIProviderProbePath:
+				require.Equal(t, "Bearer test-session", r.Header.Get("Authorization"))
+				switch probeCount.Add(1) {
+				case 1:
+					writeJSON(t, rw, http.StatusOK, map[string]string{"scaletest_llm_mock": "coder-scaletest-llm-mock:old.example.test/v1"})
+				case 2:
+					writeText(rw, http.StatusBadGateway, "upstream proxy error")
+				case 3:
+					writeText(rw, http.StatusNotFound, "route not supported")
+				default:
+					writeJSON(t, rw, http.StatusOK, map[string]string{"scaletest_llm_mock": expectedMarker})
+				}
+			default:
+				t.Fatalf("unexpected request %s %s", r.Method, r.URL.Path)
+			}
+		}))
+
+		err := waitForScaletestAIProviderRoute(context.Background(), client, testLogger(), llmMockURL)
+		require.NoError(t, err)
+		require.Equal(t, int64(4), probeCount.Load())
+	})
+
+	t.Run("SkipsWhenAIGatewayRoutingDisabled", func(t *testing.T) {
+		t.Parallel()
+
+		client := newProviderTestClient(t, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.Method == http.MethodGet && r.URL.Path == "/api/v2/deployment/config":
+				writeDeploymentConfig(t, rw, false)
+			case r.URL.Path == scaletestAIProviderProbePath:
+				t.Fatal("probe route should not be called when AI Gateway routing is disabled")
+			default:
+				t.Fatalf("unexpected request %s %s", r.Method, r.URL.Path)
+			}
+		}))
+
+		err := waitForScaletestAIProviderRoute(context.Background(), client, testLogger(), llmMockURL)
+		require.NoError(t, err)
+	})
+}
+
+func newProviderTestClient(t *testing.T, handler http.Handler) *codersdk.Client {
+	t.Helper()
+
+	srv := httptest.NewServer(handler)
+	t.Cleanup(srv.Close)
+	serverURL, err := url.Parse(srv.URL)
+	require.NoError(t, err)
+	client := codersdk.New(serverURL)
+	client.SetSessionToken("test-session")
+	return client
+}
+
+func writeDeploymentConfig(t *testing.T, rw http.ResponseWriter, enabled bool) {
+	t.Helper()
+
+	writeJSON(t, rw, http.StatusOK, map[string]any{
+		"config": map[string]any{
+			"ai": map[string]any{
+				"bridge": map[string]any{
+					"enabled": enabled,
+				},
+				"chat": map[string]any{
+					"ai_gateway_routing_enabled": enabled,
+				},
+			},
+		},
+	})
+}
+
+func writeJSON(t *testing.T, rw http.ResponseWriter, status int, body any) {
+	t.Helper()
+
+	rw.Header().Set("Content-Type", "application/json")
+	rw.WriteHeader(status)
+	require.NoError(t, json.NewEncoder(rw).Encode(body))
+}
+
+func writeText(rw http.ResponseWriter, status int, body string) {
+	rw.Header().Set("Content-Type", "text/plain")
+	rw.WriteHeader(status)
+	_, _ = rw.Write([]byte(body))
+}
diff --git a/scaletest/llmmock/server.go b/scaletest/llmmock/server.go
index 8c9bdfe3c9..2d01a41d75 100644
--- a/scaletest/llmmock/server.go
+++ b/scaletest/llmmock/server.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"net/url"
 	"strings"
 	"time"
 
@@ -50,6 +51,24 @@ type Config struct {
 	TraceEnable bool
 }
 
+const probeMarkerPrefix = "coder-scaletest-llm-mock:"
+
+// ProbeMarkerForBaseURL returns the readiness marker emitted by the mock for a provider base URL.
+func ProbeMarkerForBaseURL(rawURL string) (string, error) {
+	parsed, err := url.Parse(rawURL)
+	if err != nil {
+		return "", xerrors.Errorf("parse LLM mock URL: %w", err)
+	}
+	if parsed.Host == "" {
+		return "", xerrors.Errorf("LLM mock URL %q is missing a host", rawURL)
+	}
+	return probeMarker(parsed.Host, parsed.Path), nil
+}
+
+func probeMarker(host string, basePath string) string {
+	return probeMarkerPrefix + host + strings.TrimRight(basePath, "/")
+}
+
 type llmRequest struct {
 	Model  string `json:"model"`
 	Stream bool   `json:"stream,omitempty"`
@@ -172,6 +191,7 @@ func (s *Server) APIAddress() string {
 func (s *Server) startAPIServer(ctx context.Context) error {
 	mux := http.NewServeMux()
 
+	mux.HandleFunc("GET /v1/models", s.handleOpenAIModels)
 	mux.HandleFunc("POST /v1/chat/completions", s.handleOpenAI)
 	mux.HandleFunc("POST /v1/responses", s.handleResponses)
 	mux.HandleFunc("POST /v1/messages", s.handleAnthropic)
@@ -201,6 +221,32 @@ func (s *Server) startAPIServer(ctx context.Context) error {
 	return nil
 }
 
+func (s *Server) handleOpenAIModels(w http.ResponseWriter, r *http.Request) {
+	pproflabel.Do(r.Context(), pproflabel.Service("llm-mock"), func(ctx context.Context) {
+		s.handleOpenAIModelsWithLabels(w, r.WithContext(ctx))
+	})
+}
+
+func (s *Server) handleOpenAIModelsWithLabels(w http.ResponseWriter, r *http.Request) {
+	basePath := strings.TrimSuffix(r.URL.Path, "/")
+	basePath = strings.TrimSuffix(basePath, "/models")
+	resp := struct {
+		Object           string     `json:"object"`
+		Data             []struct{} `json:"data"`
+		ScaletestLLMMock string     `json:"scaletest_llm_mock"`
+	}{
+		Object:           "list",
+		Data:             []struct{}{},
+		ScaletestLLMMock: probeMarker(r.Host, basePath),
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	if err := json.NewEncoder(w).Encode(resp); err != nil {
+		s.logger.Error(r.Context(), "failed to write OpenAI models response", slog.Error(err))
+	}
+}
+
 func (s *Server) handleOpenAI(w http.ResponseWriter, r *http.Request) {
 	pproflabel.Do(r.Context(), pproflabel.Service("llm-mock"), func(ctx context.Context) {
 		s.handleOpenAIWithLabels(w, r.WithContext(ctx))
diff --git a/scaletest/llmmock/server_test.go b/scaletest/llmmock/server_test.go
new file mode 100644
index 0000000000..5f6fb9d857
--- /dev/null
+++ b/scaletest/llmmock/server_test.go
@@ -0,0 +1,42 @@
+package llmmock_test
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"cdr.dev/slog/v3"
+	"cdr.dev/slog/v3/sloggers/sloghuman"
+	"github.com/coder/coder/v2/scaletest/llmmock"
+)
+
+func TestServerOpenAIModelsReportsProbeMarker(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	server := new(llmmock.Server)
+	err := server.Start(ctx, llmmock.Config{
+		Address: "127.0.0.1:0",
+		Logger:  slog.Make(sloghuman.Sink(io.Discard)).Leveled(slog.LevelDebug),
+	})
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		require.NoError(t, server.Stop())
+	})
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, server.APIAddress()+"/v1/models", nil)
+	require.NoError(t, err)
+	res, err := http.DefaultClient.Do(req)
+	require.NoError(t, err)
+	defer res.Body.Close()
+	require.Equal(t, http.StatusOK, res.StatusCode)
+
+	body, err := io.ReadAll(res.Body)
+	require.NoError(t, err)
+	expectedMarker, err := llmmock.ProbeMarkerForBaseURL(server.APIAddress() + "/v1")
+	require.NoError(t, err)
+	require.Contains(t, string(body), expectedMarker)
+}