feat(images): expose temperature control for Gemini image models

backend/src/images/dto/create_imagen_dto.py

@@ -104,6 +104,18 @@ class CreateImagenDto(BaseDto):
         default=False,
         description="Whether to use Google Search for image generation.",
     )
+    temperature: float | None = Field(
+        default=None,
+        ge=0.0,
+        le=2.0,
+        description=(
+            "Sampling temperature for Gemini image models. Lower values stay "
+            "closer to the prompt and the reference images, which matters when "
+            "editing and you want the rest of the frame preserved; higher "
+            "values vary more. Left unset, the model's own default applies. "
+            "Ignored by Imagen models, which do not expose it."
+        ),
+    )
     resolution: Literal["1K", "2K", "4K"] = Field(
         default="1K",
         description="Resolution of the generated image.",

backend/src/images/imagen_service.py

@@ -467,6 +467,7 @@ def gemini_generate_image(
     aspect_ratio: str | None = None,
     google_search: bool = False,
     resolution: str | None = None,
+    temperature: float | None = None,
 ) -> types.GeneratedImage | None:
     """Generates an image using the Gemini API for text-to-image or
     image-to-image.
@@ -515,6 +516,9 @@ def gemini_generate_image(
                 response_modalities=["Text", "Image"],
                 image_config=image_config,
                 tools=tools if tools else None,
+                # Omitted when unset so the model's own default applies rather
+                # than us pinning one.
+                temperature=temperature,
             )
             response: types.GenerateContentResponse = (
                 vertexai_client.models.generate_content(
@@ -735,6 +739,7 @@ async def _async_worker():
                                         aspect_ratio=request_dto.aspect_ratio,
                                         google_search=request_dto.google_search,
                                         resolution=request_dto.resolution,
+                                        temperature=request_dto.temperature,
                                     )
                                     for _ in range(request_dto.number_of_media)
                                 ]
@@ -811,6 +816,7 @@ async def _async_worker():
                                     aspect_ratio=request_dto.aspect_ratio,
                                     google_search=request_dto.google_search,
                                     resolution=request_dto.resolution,
+                                    temperature=request_dto.temperature,
                                 )
                                 for _ in range(request_dto.number_of_media)
                             ]

backend/tests/images/test_imagen_service.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 """Tests for Imagen Service."""
 
-
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
@@ -1277,3 +1276,42 @@ def test_vto_dto_validation_failures():
     with pytest.raises(ValidationError) as exc_info:
         VtoDto(workspace_id=1, person_image=valid_input)
     assert "At least one garment" in str(exc_info.value)
+
+
+def test_gemini_generate_image_forwards_temperature():
+    """Temperature reaches the model when set.
+
+    Editing benefits from a low value: it keeps the result close to the
+    reference images so the untouched parts of the frame are preserved.
+    """
+    mock_client = MagicMock()
+    mock_client.models.generate_content.return_value = MagicMock(candidates=[])
+
+    gemini_generate_image(
+        gcs_service=MagicMock(),
+        vertexai_client=mock_client,
+        prompt="Make the sky orange",
+        model=GenerationModelEnum.GEMINI_2_5_FLASH_IMAGE,
+        bucket_name="bucket",
+        temperature=0.2,
+    )
+
+    config = mock_client.models.generate_content.call_args.kwargs["config"]
+    assert config.temperature == 0.2
+
+
+def test_gemini_generate_image_omits_temperature_when_unset():
+    """Unset means the model's own default applies, not one we chose."""
+    mock_client = MagicMock()
+    mock_client.models.generate_content.return_value = MagicMock(candidates=[])
+
+    gemini_generate_image(
+        gcs_service=MagicMock(),
+        vertexai_client=mock_client,
+        prompt="A cat",
+        model=GenerationModelEnum.GEMINI_2_5_FLASH_IMAGE,
+        bucket_name="bucket",
+    )
+
+    config = mock_client.models.generate_content.call_args.kwargs["config"]
+    assert config.temperature is None

frontend/src/app/common/components/flow-prompt-box/flow-prompt-box.component.html

@@ -85,6 +85,21 @@
             <mat-icon class="!h-4 !w-4 !flex !items-center !justify-center">{{ selectedResolution() | lowercase }}</mat-icon>
           </button>
         }
+        <!--
+          Temperature is worth seeing at a glance while iterating on an edit,
+          so it sits with the other settings rather than only inside the popup.
+        -->
+        @if (supportsTemperature) {
+          <button
+            (click)="toggleSettingsMenu(); $event.stopPropagation()"
+            [matTooltip]="temperature === null
+              ? 'Temperature: model default. Lower stays closer to the prompt and references.'
+              : 'Temperature ' + temperature + '. Lower stays closer to the prompt and references.'"
+            class="rounded-md bg-neutral-800 px-2 py-1 cursor-pointer hover:bg-neutral-700"
+          >
+            {{ temperature === null ? 'T auto' : 'T ' + temperature }}
+          </button>
+        }
       </div>
     </div>
 
@@ -479,6 +494,31 @@
           }
         </div>
 
+        <!-- Temperature: Gemini image models only -->
+        @if (supportsTemperature) {
+          <div class="relative">
+            <label for="temperature" class="block text-xs font-medium text-neutral-400 mb-1.5">
+              Temperature
+            </label>
+            <div class="flex items-center gap-2">
+              <input id="temperature" type="range" min="0" max="2" step="0.05"
+                [value]="temperature ?? 1"
+                (input)="onTemperatureInput($event)"
+                class="h-1 w-28 cursor-pointer accent-blue-600" />
+              <span class="w-8 text-right font-mono text-xs text-neutral-300">
+                {{ temperature === null ? 'auto' : temperature }}
+              </span>
+              <button *ngIf="temperature !== null"
+                (click)="temperatureChanged.emit(null)"
+                matTooltip="Use the model default"
+                class="text-[10px] text-neutral-500 hover:text-neutral-300">reset</button>
+            </div>
+            <p class="mt-1 text-[10px] text-neutral-600">
+              Lower stays closer to the prompt and references — useful when editing.
+            </p>
+          </div>
+        }
+
         <!-- Duration Dropdown -->
         @if (hasDurationOptions()) {
           <div class="relative">

frontend/src/app/common/components/flow-prompt-box/flow-prompt-box.component.ts

@@ -145,13 +145,16 @@ export class FlowPromptBoxComponent implements OnInit, OnDestroy {
   @Output() clearReferenceVideo = new EventEmitter<Event>();
   @Output() openAudioSelectorForReference = new EventEmitter<void>();
   @Output() clearReferenceAudio = new EventEmitter<Event>();
+  @Output() temperatureChanged = new EventEmitter<number | null>();
 
   @Input() image1Preview: string | null = null;
   @Input() image2Preview: string | null = null;
   @Input() referenceImages: ReferenceImage[] = [];
   @Input() referenceImagesType: 'ASSET' | 'STYLE' = 'ASSET';
   @Input() referenceVideo: any | null = null;
   @Input() referenceAudio: any | null = null;
+  /** null means "use the model's default" rather than a chosen value. */
+  @Input() temperature: number | null = null;
 
   @ViewChild('modeTrigger') modeTrigger!: ElementRef;
   @ViewChild('modeMenu') modeMenu!: ElementRef;
@@ -237,6 +240,16 @@ export class FlowPromptBoxComponent implements OnInit, OnDestroy {
     this.promptChanged.emit(target.value);
   }
 
+  /** Whether the active model accepts a sampling temperature. */
+  get supportsTemperature(): boolean {
+    return !!this.getSelectedModelObject()?.capabilities?.supportsTemperature;
+  }
+
+  onTemperatureInput(event: Event): void {
+    const value = (event.target as HTMLInputElement).value;
+    this.temperatureChanged.emit(value === '' ? null : Number(value));
+  }
+
   onEditOverlayClick(num?: NumPos, index?: number, ref?: ReferenceImage): void {
     if (num) {
       this.editImage.emit({num});

frontend/src/app/common/config/model-config.ts

@@ -37,6 +37,11 @@ export interface ModelCapability {
   supportsVoice?: boolean;
   supportsLanguage?: boolean;
   supportsSeed?: boolean;
+  /**
+   * Whether sampling temperature can be set. Gemini image models accept it;
+   * Imagen does not expose it, and Gemini Omni rejects it outright.
+   */
+  supportsTemperature?: boolean;
 }
 
 export interface GenerationModelConfig {
@@ -79,6 +84,7 @@ export const MODEL_CONFIGS: GenerationModelConfig[] = [
       ], // All
       supportedResolutions: ['1K', '2K', '4K'],
       supportedDurations: [],
+      supportsTemperature: true,
       supportsGoogleSearch: true,
     },
   },
@@ -109,6 +115,7 @@ export const MODEL_CONFIGS: GenerationModelConfig[] = [
       ], // All
       supportedResolutions: ['1K'],
       supportedDurations: [],
+      supportsTemperature: true,
       supportsGoogleSearch: true,
     },
   },
@@ -135,6 +142,7 @@ export const MODEL_CONFIGS: GenerationModelConfig[] = [
       ], // All
       supportedResolutions: ['1K', '2K', '4K'],
       supportedDurations: [],
+      supportsTemperature: true,
       supportsGoogleSearch: true,
     },
   },
@@ -161,6 +169,7 @@ export const MODEL_CONFIGS: GenerationModelConfig[] = [
       ],
       supportedResolutions: ['1K', '2K', '4K'],
       supportedDurations: [],
+      supportsTemperature: true,
     },
   },
 

frontend/src/app/common/models/search.model.ts

@@ -32,6 +32,11 @@ export type ImagenRequest = {
   useBrandGuidelines: boolean;
   enhancePrompt?: boolean;
   googleSearch?: boolean;
+  /**
+   * Sampling temperature for Gemini image models. Undefined means the
+   * model's own default. Imagen and Gemini Omni do not accept it.
+   */
+  temperature?: number;
   resolution?: '1K' | '2K' | '4K';
 };
 

frontend/src/app/home/home.component.html

@@ -383,6 +383,8 @@
           (promptChanged)="onPromptChanged($event)" (aspectRatioChanged)="onAspectRatioChanged($event)"
           (resolutionChanged)="onResolutionChanged($event)" (outputsChanged)="onOutputsChanged($event)"
           (generateClicked)="onGenerateClicked()" (rewriteClicked)="onRewriteClicked()"
+          [temperature]="searchRequest.temperature ?? null"
+          (temperatureChanged)="onTemperatureChanged($event)"
           (modelSelected)="onModelSelected($event)" (openImageSelectorForReference)="onOpenImageSelectorForReference()"
           (onReferenceImageDrop)="onReferenceImageDrop($event)" (clearReferenceImage)="onClearReferenceImage($event)"
           (editReferenceImage)="onEditPromptReferenceImage($event)"

frontend/src/app/home/home.component.ts

@@ -854,6 +854,11 @@ export class HomeComponent implements OnInit, AfterViewInit, OnDestroy {
       });
   }
 
+  onTemperatureChanged(value: number | null): void {
+    this.searchRequest.temperature = value ?? undefined;
+    this.saveState();
+  }
+
   resetAllFilters() {
     this.searchRequest = {
       prompt: '',