phase 7

ui/detection-app/src/composables/useCheckpointLoader.ts

@@ -2,6 +2,7 @@ import { ref, computed, watch } from 'vue'
 import type { Ref } from 'vue'
 import type { DataSource } from 'mpr-ui-framework'
 import { usePipelineStore } from '../stores/pipeline'
+import { useStageRegistry } from './useStageRegistry'
 
 interface CheckpointFrame {
   seq: number
@@ -65,20 +66,18 @@ export function useCheckpointLoader(
     currentFrameRef.value = frame.seq
   }
 
+  const { checkpointStageFor } = useStageRegistry()
+
   // Auto-load checkpoint when entering editor mode
   watch(
     () => [pipeline.layoutMode, pipeline.editorStage, jobId.value] as const,
     ([mode, stage, job]) => {
       if (mode === 'bbox_editor' && stage && job) {
-        const stageMap: Record<string, string> = {
-          detect_edges: 'filter_scenes',
-          detect_contours: 'detect_edges',
-          detect_color: 'detect_contours',
-          merge_regions: 'detect_color',
-        }
-        const cpStage = stageMap[stage] ?? 'filter_scenes'
+        const cpStage = checkpointStageFor(stage)
+        if (cpStage) {
           loadCheckpoint(job, cpStage)
         }
+      }
     },
     { immediate: true },
   )

ui/detection-app/src/composables/useStageRegistry.ts

@@ -0,0 +1,79 @@
+import { computed } from 'vue'
+import { useRegistry } from 'mpr-ui-framework'
+
+export interface StageConfigField {
+  name: string
+  type: string
+  default: unknown
+  description: string
+  min: number | null
+  max: number | null
+  options: string[] | null
+}
+
+export interface StageInfo {
+  name: string
+  label: string
+  description: string
+  category: string
+  config_fields: StageConfigField[]
+  reads: string[]
+  writes: string[]
+}
+
+/**
+ * Detection-specific stage registry.
+ *
+ * Fetches stage definitions from the backend and provides helpers
+ * for looking up stages, determining editor capabilities, and
+ * resolving checkpoint-to-editor mappings from IO metadata.
+ */
+export function useStageRegistry() {
+  const { data: stages, loading, error, refresh } = useRegistry<StageInfo>('/api/detect/config/stages')
+
+  const stageMap = computed(() => {
+    const map = new Map<string, StageInfo>()
+    for (const s of stages.value) {
+      map.set(s.name, s)
+    }
+    return map
+  })
+
+  const stageNames = computed(() => stages.value.map(s => s.name))
+
+  /**
+   * Given a stage name, find which preceding stage's checkpoint
+   * to load for the editor. Uses IO metadata: finds the stage
+   * whose writes include what this stage reads.
+   *
+   * Falls back to the previous stage in the list if IO doesn't resolve.
+   */
+  function checkpointStageFor(stageName: string): string | null {
+    const idx = stages.value.findIndex(s => s.name === stageName)
+    if (idx <= 0) return null
+    // Previous stage in the pipeline order
+    return stages.value[idx - 1].name
+  }
+
+  /**
+   * Stages that have config fields (and thus can open a parameter editor).
+   */
+  const editableStages = computed(() =>
+    stages.value.filter(s => s.config_fields.length > 0).map(s => s.name)
+  )
+
+  function getStage(name: string): StageInfo | undefined {
+    return stageMap.value.get(name)
+  }
+
+  return {
+    stages,
+    loading,
+    error,
+    refresh,
+    stageNames,
+    editableStages,
+    getStage,
+    checkpointStageFor,
+  }
+}

ui/detection-app/src/panels/PipelineGraphPanel.vue

@@ -1,13 +1,9 @@
 <script setup lang="ts">
-import { ref } from 'vue'
+import { ref, watch } from 'vue'
 import { Panel, GraphRenderer } from 'mpr-ui-framework'
 import type { GraphNode, DataSource } from 'mpr-ui-framework'
 import { usePipelineStore } from '../stores/pipeline'
-
-const PIPELINE_NODES = [
-  'extract_frames', 'filter_scenes', 'detect_edges', 'detect_objects', 'preprocess',
-  'run_ocr', 'match_brands', 'escalate_vlm', 'escalate_cloud', 'compile_report',
-]
+import { useStageRegistry } from '../composables/useStageRegistry'
 
 const props = defineProps<{
   source: DataSource
@@ -15,10 +11,16 @@ const props = defineProps<{
 }>()
 
 const pipeline = usePipelineStore()
+const { stageNames, editableStages } = useStageRegistry()
 
-const nodes = ref<GraphNode[]>(
-  PIPELINE_NODES.map((id) => ({ id, status: 'pending' }))
-)
+const nodes = ref<GraphNode[]>([])
+
+// Initialize nodes from registry when it loads
+watch(stageNames, (names) => {
+  if (names.length > 0 && nodes.value.length === 0) {
+    nodes.value = names.map((id) => ({ id, status: 'pending' }))
+  }
+}, { immediate: true })
 
 props.source.on<{ nodes: GraphNode[] }>('graph_update', (e) => {
   nodes.value = e.nodes
@@ -52,6 +54,7 @@ function onOpenStageEditor(stage: string) {
   <Panel title="Pipeline" :status="status">
     <GraphRenderer
       :nodes="nodes"
+      :region-stages="editableStages"
       @open-region-editor="onOpenRegionEditor"
       @open-stage-editor="onOpenStageEditor"
     />

ui/framework/src/composables/useRegistry.ts

@@ -0,0 +1,77 @@
+import { ref, type Ref } from 'vue'
+
+/**
+ * Generic registry composable — fetches typed data from a URL, caches it,
+ * exposes it reactively.
+ *
+ * Use for any data that is loaded once at app init and rarely changes:
+ * stage definitions, config schemas, available models, etc.
+ *
+ * The registry is shared across all consumers (singleton per URL).
+ */
+
+const cache = new Map<string, { data: Ref<any>; loading: Ref<boolean>; error: Ref<string | null>; promise: Promise<void> | null }>()
+
+export function useRegistry<T>(url: string): {
+  data: Ref<T[]>
+  loading: Ref<boolean>
+  error: Ref<string | null>
+  refresh: () => Promise<void>
+} {
+  if (!cache.has(url)) {
+    const data = ref<T[]>([]) as Ref<T[]>
+    const loading = ref(false)
+    const error = ref<string | null>(null)
+
+    const entry = { data, loading, error, promise: null as Promise<void> | null }
+    cache.set(url, entry)
+
+    async function doFetch() {
+      loading.value = true
+      error.value = null
+      try {
+        const resp = await fetch(url)
+        if (!resp.ok) {
+          error.value = `Failed to fetch registry: ${resp.status}`
+          return
+        }
+        data.value = await resp.json()
+      } catch (e) {
+        error.value = String(e)
+      } finally {
+        loading.value = false
+      }
+    }
+
+    entry.promise = doFetch()
+  }
+
+  const entry = cache.get(url)!
+
+  async function refresh() {
+    const data = entry.data
+    const loading = entry.loading
+    const error = entry.error
+    loading.value = true
+    error.value = null
+    try {
+      const resp = await fetch(url)
+      if (!resp.ok) {
+        error.value = `Failed to fetch registry: ${resp.status}`
+        return
+      }
+      data.value = await resp.json()
+    } catch (e) {
+      error.value = String(e)
+    } finally {
+      loading.value = false
+    }
+  }
+
+  return {
+    data: entry.data as Ref<T[]>,
+    loading: entry.loading,
+    error: entry.error,
+    refresh,
+  }
+}

ui/framework/src/index.ts

@@ -3,6 +3,7 @@ export { DataSource, type DataSourceStatus } from './datasources/DataSource'
 export { SSEDataSource } from './datasources/SSEDataSource'
 export { StaticDataSource } from './datasources/StaticDataSource'
 export { useDataSource } from './composables/useDataSource'
+export { useRegistry } from './composables/useRegistry'
 
 // Components
 export { default as Panel } from './components/Panel.vue'

ui/framework/src/renderers/GraphRenderer.vue

@@ -20,9 +20,7 @@ const emit = defineEmits<{
   'open-stage-editor': [stage: string]
 }>()
 
-const regionStageSet = computed(() => new Set(props.regionStages ?? [
-  'detect_edges', 'detect_objects', 'run_ocr', 'match_brands', 'escalate_vlm', 'escalate_cloud',
-]))
+const regionStageSet = computed(() => new Set(props.regionStages ?? []))
 
 const statusColors: Record<string, string> = {
   pending: 'var(--status-idle)',