feat(lora-cycler): add sequential LoRA cycling through filtered pool

Add Lora Cycler node that cycles through LoRAs sequentially from a filtered pool. Supports configurable sort order, strength settings, and persists cycle progress across workflow save/load.

Backend:
- New LoraCyclerNode with cycle() method
- New /api/lm/loras/cycler-list endpoint
- LoraService.get_cycler_list() for filtered/sorted list

Frontend:
- LoraCyclerWidget with Vue.js component
- useLoraCyclerState composable
- LoraCyclerSettingsView for UI display

vue-widgets/src/composables/useLoraCyclerState.ts

@@ -0,0 +1,208 @@
+import { ref, watch, computed } from 'vue'
+import type { ComponentWidget, CyclerConfig, LoraPoolConfig } from './types'
+
+export interface CyclerLoraItem {
+  file_name: string
+  model_name: string
+}
+
+export function useLoraCyclerState(widget: ComponentWidget) {
+  // State refs
+  const currentIndex = ref(1)  // 1-based
+  const totalCount = ref(0)
+  const poolConfigHash = ref('')
+  const modelStrength = ref(1.0)
+  const clipStrength = ref(1.0)
+  const useCustomClipRange = ref(false)
+  const sortBy = ref<'filename' | 'model_name'>('filename')
+  const currentLoraName = ref('')
+  const currentLoraFilename = ref('')
+  const isLoading = ref(false)
+
+  // Build config object from current state
+  const buildConfig = (): CyclerConfig => ({
+    current_index: currentIndex.value,
+    total_count: totalCount.value,
+    pool_config_hash: poolConfigHash.value,
+    model_strength: modelStrength.value,
+    clip_strength: clipStrength.value,
+    use_same_clip_strength: !useCustomClipRange.value,
+    sort_by: sortBy.value,
+    current_lora_name: currentLoraName.value,
+    current_lora_filename: currentLoraFilename.value,
+  })
+
+  // Restore state from config object
+  const restoreFromConfig = (config: CyclerConfig) => {
+    currentIndex.value = config.current_index || 1
+    totalCount.value = config.total_count || 0
+    poolConfigHash.value = config.pool_config_hash || ''
+    modelStrength.value = config.model_strength ?? 1.0
+    clipStrength.value = config.clip_strength ?? 1.0
+    useCustomClipRange.value = !(config.use_same_clip_strength ?? true)
+    sortBy.value = config.sort_by || 'filename'
+    currentLoraName.value = config.current_lora_name || ''
+    currentLoraFilename.value = config.current_lora_filename || ''
+  }
+
+  // Generate hash from pool config for change detection
+  const hashPoolConfig = (poolConfig: LoraPoolConfig | null): string => {
+    if (!poolConfig || !poolConfig.filters) {
+      return ''
+    }
+    try {
+      return btoa(JSON.stringify(poolConfig.filters))
+    } catch {
+      return ''
+    }
+  }
+
+  // Fetch cycler list from API
+  const fetchCyclerList = async (
+    poolConfig: LoraPoolConfig | null
+  ): Promise<CyclerLoraItem[]> => {
+    try {
+      isLoading.value = true
+
+      const requestBody: Record<string, unknown> = {
+        sort_by: sortBy.value,
+      }
+
+      if (poolConfig?.filters) {
+        requestBody.pool_config = poolConfig.filters
+      }
+
+      const response = await fetch('/api/lm/loras/cycler-list', {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify(requestBody),
+      })
+
+      if (!response.ok) {
+        const errorData = await response.json()
+        throw new Error(errorData.error || 'Failed to fetch cycler list')
+      }
+
+      const data = await response.json()
+
+      if (!data.success) {
+        throw new Error(data.error || 'Failed to get cycler list')
+      }
+
+      return data.loras || []
+    } catch (error) {
+      console.error('[LoraCyclerState] Error fetching cycler list:', error)
+      throw error
+    } finally {
+      isLoading.value = false
+    }
+  }
+
+  // Refresh list and update state
+  const refreshList = async (poolConfig: LoraPoolConfig | null) => {
+    try {
+      const newHash = hashPoolConfig(poolConfig)
+      const hashChanged = newHash !== poolConfigHash.value
+
+      // Fetch the list
+      const loraList = await fetchCyclerList(poolConfig)
+
+      // Update total count
+      totalCount.value = loraList.length
+
+      // If pool config changed, reset index to 1
+      if (hashChanged) {
+        currentIndex.value = 1
+        poolConfigHash.value = newHash
+      }
+
+      // Clamp index to valid range
+      if (currentIndex.value > totalCount.value) {
+        currentIndex.value = Math.max(1, totalCount.value)
+      }
+
+      // Update current LoRA info
+      if (loraList.length > 0 && currentIndex.value > 0) {
+        const currentLora = loraList[currentIndex.value - 1]
+        if (currentLora) {
+          currentLoraName.value = sortBy.value === 'filename' 
+            ? currentLora.file_name 
+            : (currentLora.model_name || currentLora.file_name)
+          currentLoraFilename.value = currentLora.file_name
+        }
+      } else {
+        currentLoraName.value = ''
+        currentLoraFilename.value = ''
+      }
+
+      return loraList
+    } catch (error) {
+      console.error('[LoraCyclerState] Error refreshing list:', error)
+      throw error
+    }
+  }
+
+  // Set index manually
+  const setIndex = (index: number) => {
+    if (index >= 1 && index <= totalCount.value) {
+      currentIndex.value = index
+    }
+  }
+
+  // Computed property to check if clip strength is disabled
+  const isClipStrengthDisabled = computed(() => !useCustomClipRange.value)
+
+  // Watch model strength changes to sync with clip strength when not using custom range
+  watch(modelStrength, (newValue) => {
+    if (!useCustomClipRange.value) {
+      clipStrength.value = newValue
+    }
+  })
+
+  // Watch all state changes and update widget value
+  watch([
+    currentIndex,
+    totalCount,
+    poolConfigHash,
+    modelStrength,
+    clipStrength,
+    useCustomClipRange,
+    sortBy,
+    currentLoraName,
+    currentLoraFilename,
+  ], () => {
+    const config = buildConfig()
+    if (widget.updateConfig) {
+      widget.updateConfig(config)
+    } else {
+      widget.value = config
+    }
+  }, { deep: true })
+
+  return {
+    // State refs
+    currentIndex,
+    totalCount,
+    poolConfigHash,
+    modelStrength,
+    clipStrength,
+    useCustomClipRange,
+    sortBy,
+    currentLoraName,
+    currentLoraFilename,
+    isLoading,
+
+    // Computed
+    isClipStrengthDisabled,
+
+    // Methods
+    buildConfig,
+    restoreFromConfig,
+    hashPoolConfig,
+    fetchCyclerList,
+    refreshList,
+    setIndex,
+  }
+}