coder · ThomasK33 · Jul 10, 2026 · Jul 9, 2026
diff --git a/coderd/x/chatd/quickgen.go b/coderd/x/chatd/quickgen.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"net/http"
 	"slices"
 	"strings"
 	"time"
@@ -54,9 +55,57 @@ const titleGenerationPrompt = "Write a short title for the user's message. " +
 // quickgenTemperature keeps title and status-label output stable
 // across repeated runs over the same input. Fantasy providers drop
 // this with a call warning for models that reject it (OpenAI
-// reasoning models, Anthropic thinking models).
+// reasoning models, Anthropic thinking models), but only for model
+// names they recognize. generateQuickgenObject handles models that
+// reject the parameter at the API instead.
 const quickgenTemperature = 0.0
 
+// generateQuickgenObject generates a structured object with provider
+// retries and the pinned quickgen temperature. Model aliases served
+// through gateways such as AI Bridge are not recognized by fantasy's
+// per-model parameter stripping and can reject temperature with a
+// bad-request error, so the call is retried without temperature when
+// the model rejects it.
+func generateQuickgenObject[T any](
+	ctx context.Context,
+	model fantasy.LanguageModel,
+	call fantasy.ObjectCall,
+) (*fantasy.ObjectResult[T], error) {
+	call.Temperature = ptr.Ref(quickgenTemperature)
+	var result *fantasy.ObjectResult[T]
+	err := chatretry.Retry(ctx, func(retryCtx context.Context) error {
+		var genErr error
+		result, genErr = object.Generate[T](retryCtx, model, call)
+		if call.Temperature != nil && isTemperatureRejectedError(genErr) {
+			// The model rejects the temperature parameter. Drop it
+			// for this and any later retry attempts.
+			call.Temperature = nil
+			result, genErr = object.Generate[T](retryCtx, model, call)
+		}
+		return genErr
+	}, nil)
+	return result, err
+}
+
+// isTemperatureRejectedError reports whether a provider rejected the
+// request because the model does not accept the temperature parameter,
+// for example Anthropic's "`temperature` is deprecated for this model."
+// or OpenAI's "Unsupported parameter: 'temperature' is not supported
+// with this model.". Quickgen only sends a valid temperature value, so
+// any bad-request response mentioning temperature means the model
+// rejects the parameter itself.
+func isTemperatureRejectedError(err error) bool {
+	var providerErr *fantasy.ProviderError
+	if !errors.As(err, &providerErr) {
+		return false
+	}
+	if providerErr.StatusCode != http.StatusBadRequest {
+		return false
+	}
+	text := strings.ToLower(providerErr.Error() + " " + string(providerErr.ResponseBody))
+	return strings.Contains(text, "temperature")
+}
+
 const (
 	// maxConversationContextRunes caps the conversation sample in manual
 	// title prompts to avoid exceeding model context windows.
@@ -555,19 +604,13 @@ func generateStructuredTitleWithUsage(
 	}
 
 	var maxOutputTokens int64 = 256
-	var result *fantasy.ObjectResult[generatedTitle]
-	err := chatretry.Retry(ctx, func(retryCtx context.Context) error {
-		var genErr error
-		result, genErr = object.Generate[generatedTitle](retryCtx, model, fantasy.ObjectCall{
-			Prompt:            prompt,
-			SchemaName:        "propose_title",
-			SchemaDescription: "Propose a short chat title.",
-			MaxOutputTokens:   &maxOutputTokens,
-			Temperature:       ptr.Ref(quickgenTemperature),
-			ProviderOptions:   providerOptions,
-		})
-		return genErr
-	}, nil)
+	result, err := generateQuickgenObject[generatedTitle](ctx, model, fantasy.ObjectCall{
+		Prompt:            prompt,
+		SchemaName:        "propose_title",
+		SchemaDescription: "Propose a short chat title.",
+		MaxOutputTokens:   &maxOutputTokens,
+		ProviderOptions:   providerOptions,
+	})
 	if err != nil {
 		var usage fantasy.Usage
 		var noObjErr *fantasy.NoObjectGeneratedError
@@ -1023,18 +1066,12 @@ func generateStructuredTurnStatusLabel(
 	}
 
 	var maxOutputTokens int64 = 64
-	var result *fantasy.ObjectResult[generatedTurnStatusLabel]
-	err := chatretry.Retry(ctx, func(retryCtx context.Context) error {
-		var genErr error
-		result, genErr = object.Generate[generatedTurnStatusLabel](retryCtx, model, fantasy.ObjectCall{
-			Prompt:            prompt,
-			SchemaName:        "propose_turn_status_label",
-			SchemaDescription: "Propose a compact chat status label.",
-			MaxOutputTokens:   &maxOutputTokens,
-			Temperature:       ptr.Ref(quickgenTemperature),
-		})
-		return genErr
-	}, nil)
+	result, err := generateQuickgenObject[generatedTurnStatusLabel](ctx, model, fantasy.ObjectCall{
+		Prompt:            prompt,
+		SchemaName:        "propose_turn_status_label",
+		SchemaDescription: "Propose a compact chat status label.",
+		MaxOutputTokens:   &maxOutputTokens,
+	})
 	if err != nil {
 		return "", xerrors.Errorf("generate structured turn status label: %w", err)
 	}

diff --git a/coderd/x/chatd/quickgen_internal_test.go b/coderd/x/chatd/quickgen_internal_test.go
@@ -17,6 +17,7 @@ import (
 	"github.com/sqlc-dev/pqtype"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/mock/gomock"
+	"golang.org/x/xerrors"
 
 	"cdr.dev/slog/v3/sloggers/slogtest"
 	"github.com/coder/coder/v2/coderd/database"
@@ -901,6 +902,48 @@ func TestGenerateStructuredTitleWithUsage_OpenAICompatibleRequiredToolChoice(t *
 		"title generation should pin temperature for repeatable output")
 }
 
+// newTemperatureRejectedError mirrors the bad-request error returned
+// through AI Bridge by models that do not accept the temperature
+// parameter.
+func newTemperatureRejectedError() *fantasy.ProviderError {
+	return &fantasy.ProviderError{
+		Title: "bad request",
+		Message: `POST "http://coder-aibridge/v1/messages": 400 Bad Request ` +
+			`{"error":{"message":"` + "`temperature`" + ` is deprecated for this model.",` +
+			`"type":"invalid_request_error"},"request_id":"","type":"error"}`,
+		StatusCode: http.StatusBadRequest,
+	}
+}
+
+func TestGenerateStructuredTitleWithUsage_DropsRejectedTemperature(t *testing.T) {
+	t.Parallel()
+
+	var sawTemperature []bool
+	model := &chattest.FakeModel{
+		GenerateObjectFn: func(_ context.Context, call fantasy.ObjectCall) (*fantasy.ObjectResponse, error) {
+			sawTemperature = append(sawTemperature, call.Temperature != nil)
+			if call.Temperature != nil {
+				return nil, newTemperatureRejectedError()
+			}
+			return &fantasy.ObjectResponse{
+				Object: map[string]any{"title": "Failed workspace logs"},
+			}, nil
+		},
+	}
+
+	title, _, err := generateStructuredTitleWithUsage(
+		t.Context(),
+		model,
+		nil,
+		titleGenerationPrompt,
+		"summarize failed workspace build logs",
+	)
+	require.NoError(t, err)
+	require.Equal(t, "Failed workspace logs", title)
+	require.Equal(t, []bool{true, false}, sawTemperature,
+		"generation should retry without temperature after the model rejects it")
+}
+
 func newOpenAICompatStructuredOutputServer(
 	t *testing.T,
 	toolName string,
@@ -1013,6 +1056,50 @@ func TestGenerateStructuredTurnStatusLabel(t *testing.T) {
 			"status-label generation should pin temperature for repeatable output")
 	})
 
+	t.Run("drops temperature when model rejects it", func(t *testing.T) {
+		t.Parallel()
+
+		var sawTemperature []bool
+		model := &chattest.FakeModel{
+			GenerateObjectFn: func(_ context.Context, call fantasy.ObjectCall) (*fantasy.ObjectResponse, error) {
+				sawTemperature = append(sawTemperature, call.Temperature != nil)
+				if call.Temperature != nil {
+					return nil, newTemperatureRejectedError()
+				}
+				return &fantasy.ObjectResponse{
+					Object: map[string]any{"label": "Submitted PR"},
+				}, nil
+			},
+		}
+
+		label, err := generateStructuredTurnStatusLabel(t.Context(), model, turnStatusLabelPrompt, "done")
+		require.NoError(t, err)
+		require.Equal(t, "Submitted PR", label)
+		require.Equal(t, []bool{true, false}, sawTemperature,
+			"generation should retry without temperature after the model rejects it")
+	})
+
+	t.Run("surfaces unrelated bad request errors", func(t *testing.T) {
+		t.Parallel()
+
+		var calls int
+		model := &chattest.FakeModel{
+			GenerateObjectFn: func(_ context.Context, _ fantasy.ObjectCall) (*fantasy.ObjectResponse, error) {
+				calls++
+				return nil, &fantasy.ProviderError{
+					Title:      "bad request",
+					Message:    "tools.0.custom.input_schema: JSON schema is invalid",
+					StatusCode: http.StatusBadRequest,
+				}
+			},
+		}
+
+		_, err := generateStructuredTurnStatusLabel(t.Context(), model, turnStatusLabelPrompt, "done")
+		require.ErrorContains(t, err, "JSON schema is invalid")
+		require.Equal(t, 1, calls,
+			"bad requests unrelated to temperature should not trigger a second attempt")
+	})
+
 	t.Run("rejects narrative label", func(t *testing.T) {
 		t.Parallel()
 
@@ -1037,6 +1124,72 @@ func TestGenerateStructuredTurnStatusLabel(t *testing.T) {
 	})
 }
 
+func TestIsTemperatureRejectedError(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{
+			name: "nil error",
+			err:  nil,
+			want: false,
+		},
+		{
+			name: "plain error mentioning temperature",
+			err:  xerrors.New("temperature is deprecated for this model"),
+			want: false,
+		},
+		{
+			name: "bad request rejecting temperature",
+			err:  newTemperatureRejectedError(),
+			want: true,
+		},
+		{
+			name: "wrapped bad request rejecting temperature",
+			err:  xerrors.Errorf("tool-based generation failed: %w", newTemperatureRejectedError()),
+			want: true,
+		},
+		{
+			name: "bad request with temperature only in response body",
+			err: &fantasy.ProviderError{
+				Title:        "bad request",
+				Message:      "provider request failed",
+				StatusCode:   http.StatusBadRequest,
+				ResponseBody: []byte(`{"error":{"message":"Unsupported parameter: 'temperature' is not supported with this model."}}`),
+			},
+			want: true,
+		},
+		{
+			name: "bad request unrelated to temperature",
+			err: &fantasy.ProviderError{
+				Title:      "bad request",
+				Message:    "tools.0.custom.input_schema: JSON schema is invalid",
+				StatusCode: http.StatusBadRequest,
+			},
+			want: false,
+		},
+		{
+			name: "server error mentioning temperature",
+			err: &fantasy.ProviderError{
+				Title:      "internal server error",
+				Message:    "temperature processing failed",
+				StatusCode: http.StatusInternalServerError,
+			},
+			want: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			require.Equal(t, tt.want, isTemperatureRejectedError(tt.err))
+		})
+	}
+}
+
 func mustChatMessage(
 	t *testing.T,
 	role database.ChatMessageRole,