diff --git a/ui/detection-app/src/App.vue b/ui/detection-app/src/App.vue
index b07be31..2e38800 100644
--- a/ui/detection-app/src/App.vue
+++ b/ui/detection-app/src/App.vue
@@ -138,7 +138,7 @@ function onJobStarted(newJobId: string) {
         <!-- === BBOX EDITOR MODE === -->
         <div v-else-if="pipeline.layoutMode === 'bbox_editor'" class="editor-layout">
           <div class="editor-top">
-            <SplitPane direction="horizontal" :initial-size="210" size-mode="px" :min="210" :max="350" anchor="second">
+            <SplitPane direction="horizontal" :initial-size="245" size-mode="px" :min="245" :max="350" anchor="second">
               <template #first>
                 <FramePanel :source="source" :status="status" :overlays="editorOverlays" :frame-image="currentFrameImage" :editor-boxes="editorBoxes" />
               </template>
diff --git a/ui/detection-app/src/components/StageConfigSliders.vue b/ui/detection-app/src/components/StageConfigSliders.vue
index e4a0fdd..19d50d2 100644
--- a/ui/detection-app/src/components/StageConfigSliders.vue
+++ b/ui/detection-app/src/components/StageConfigSliders.vue
@@ -1,5 +1,7 @@
 <script setup lang="ts">
-import { ref, onMounted, computed, watch } from 'vue'
+import { ref, onMounted, watch } from 'vue'
+import { ParameterEditor, useEditorExecution } from 'mpr-ui-framework'
+import type { ConfigField } from 'mpr-ui-framework'
 import {
   runEdgeDetection,
   runEdgeDetectionDebug,
@@ -8,30 +10,13 @@ import {
 } from '@/cv'
 import type { EdgeDetectionParams } from '@/cv'
 
-interface ConfigField {
-  name: string
-  type: string
-  default: unknown
-  description: string
-  min: number | null
-  max: number | null
-  options: string[] | null
-}
-
 const props = defineProps<{
-  /** Stage name (e.g. "detect_edges") */
   stage: string
-  /** Job ID (used for server mode fallback) */
   jobId: string
-  /** Currently displayed frame image (base64 JPEG) */
   frameImage?: string | null
-  /** Currently displayed frame sequence number */
   frameRef?: number | null
-  /** All checkpoint frames — when provided, Apply runs on the selection range */
   frames?: Array<{ seq: number; jpeg_b64: string }>
-  /** Index into frames[] for selection start (default 0) */
   selectionStart?: number
-  /** Index into frames[] for selection end (default frames.length - 1) */
   selectionEnd?: number
 }>()
 
@@ -46,14 +31,10 @@ const emit = defineEmits<{
 
 const fields = ref<ConfigField[]>([])
 const values = ref<Record<string, unknown>>({})
-const loading = ref(false)
-const error = ref<string | null>(null)
 const regionCount = ref<number | null>(null)
 const debugEnabled = ref(true)
-const autoApply = ref(true)  // auto-run on slider change (fast CV); uncheck for heavy stages
 const execMode = ref<'local' | 'server'>('local')
-const execTimeMs = ref<number | null>(null)
-const processingIndex = ref<number | null>(null)  // current frame index during multi-frame run
+const processingIndex = ref<number | null>(null)
 
 // Config field defaults for detect_edges (used when API is unavailable)
 const EDGE_DEFAULTS: ConfigField[] = [
@@ -67,8 +48,27 @@ const EDGE_DEFAULTS: ConfigField[] = [
   { name: 'edge_pair_min_distance', type: 'int', default: 15, description: 'Min pair distance (px)', min: 5, max: 200, options: null },
 ]
 
+// --- Execution logic (detection-specific) ---
+
+async function executeDetection() {
+  const hasFrames = props.frames && props.frames.length > 0
+  if (!props.frameImage && !hasFrames) return
+
+  if (execMode.value === 'local') {
+    await runLocal()
+  } else {
+    await runServer()
+  }
+}
+
+const {
+  loading, error, autoApply, execTimeMs,
+  apply: applyDetection, onParameterChange,
+} = useEditorExecution(executeDetection)
+
+// --- Init ---
+
 onMounted(async () => {
-  // Try loading from API, fall back to hardcoded defaults
   try {
     const resp = await fetch(`/api/detect/config/stages/${props.stage}`)
     if (resp.ok) {
@@ -85,26 +85,25 @@ onMounted(async () => {
     values.value[f.name] = f.default
   }
 
-  // Auto-run on first frame if already available
   if (props.frameImage) {
     applyDetection()
   }
 })
 
-// Auto-run when frame arrives after mount (checkpoint load is async)
 watch(() => props.frameImage, (newVal, oldVal) => {
   if (newVal && !oldVal && fields.value.length > 0) {
     applyDetection()
   }
 })
 
-// Auto-run when selection range changes (strip handle drag)
 watch([() => props.selectionStart, () => props.selectionEnd], () => {
-  if (autoApply.value) onSliderChange()
+  if (autoApply.value) onParameterChange()
 })
 
-const numericFields = computed(() => fields.value.filter(f => f.type === 'int' || f.type === 'float'))
-const boolFields = computed(() => fields.value.filter(f => f.type === 'bool'))
+function onFieldUpdate(name: string, value: unknown) {
+  values.value[name] = value
+  onParameterChange()
+}
 
 function resetDefaults() {
   for (const f of fields.value) {
@@ -113,42 +112,9 @@ function resetDefaults() {
   applyDetection()
 }
 
-let debounceTimer: ReturnType<typeof setTimeout> | null = null
+// --- Local CV execution ---
 
-function onSliderChange() {
-  if (!autoApply.value) return
-  if (debounceTimer) clearTimeout(debounceTimer)
-  debounceTimer = setTimeout(() => applyDetection(), 150)
-}
-
-async function applyDetection() {
-  const hasFrames = props.frames && props.frames.length > 0
-  if (!props.frameImage && !hasFrames) {
-    error.value = 'No frame available'
-    return
-  }
-
-  loading.value = true
-  error.value = null
-  execTimeMs.value = null
-
-  try {
-    if (execMode.value === 'local') {
-      await runLocal()
-    } else {
-      await runServer()
-    }
-  } catch (e) {
-    error.value = `${execMode.value} failed: ${e}`
-  } finally {
-    loading.value = false
-  }
-}
-
-/** Browser-side CV — runs on current frame or selection range */
 async function runLocal() {
-  const t0 = performance.now()
-
   const params: Partial<EdgeDetectionParams> = {
     cannyLow: values.value['edge_canny_low'] as number,
     cannyHigh: values.value['edge_canny_high'] as number,
@@ -159,7 +125,6 @@ async function runLocal() {
     pairMinDistance: values.value['edge_pair_min_distance'] as number,
   }
 
-  // Determine which frames to process
   const targetFrames = props.frames && props.frames.length > 0
     ? props.frames.slice(props.selectionStart ?? 0, (props.selectionEnd ?? props.frames.length - 1) + 1)
     : [{ seq: props.frameRef ?? 0, jpeg_b64: props.frameImage! }]
@@ -195,19 +160,18 @@ async function runLocal() {
       totalRegions += result.regions.length
       regions_by_frame[frameKey] = result.regions
     }
+
+    // Emit incrementally so overlays appear per frame, not all at once
+    emit('replay-result', { regions_by_frame: { ...regions_by_frame }, debug: { ...debug }, frameWidth, frameHeight })
   }
 
   processingIndex.value = null
-  execTimeMs.value = Math.round(performance.now() - t0)
   regionCount.value = totalRegions
-
-  emit('replay-result', { regions_by_frame, debug, frameWidth, frameHeight })
 }
 
-/** Server-side CV — calls GPU box via proxy */
-async function runServer() {
-  const t0 = performance.now()
+// --- Server CV execution ---
 
+async function runServer() {
   const body: Record<string, unknown> = { image: props.frameImage }
   for (const f of fields.value) {
     if (f.name !== 'enabled') {
@@ -231,7 +195,6 @@ async function runServer() {
   }
 
   const data = await resp.json()
-  execTimeMs.value = Math.round(performance.now() - t0)
   regionCount.value = data.regions?.length ?? 0
 
   const frameKey = String(props.frameRef ?? 0)
@@ -260,59 +223,24 @@ async function runServer() {
       <button class="sliders-reset" @click="resetDefaults" title="Reset to defaults">Reset</button>
     </div>
 
-    <!-- Local / Server toggle -->
     <div class="mode-toggle">
-      <button
-        :class="['mode-btn', { active: execMode === 'local' }]"
-        @click="execMode = 'local'"
-      >Local</button>
-      <button
-        :class="['mode-btn', { active: execMode === 'server' }]"
-        @click="execMode = 'server'"
-      >Server</button>
+      <button :class="['mode-btn', { active: execMode === 'local' }]" @click="execMode = 'local'">Local</button>
+      <button :class="['mode-btn', { active: execMode === 'server' }]" @click="execMode = 'server'">Server</button>
     </div>
 
     <div v-if="error" class="sliders-error">{{ error }}</div>
 
     <div class="sliders-list">
-      <!-- Boolean fields -->
-      <label v-for="f in boolFields" :key="f.name" class="slider-field bool-field">
-        <input
-          type="checkbox"
-          :checked="!!values[f.name]"
-          @change="(e) => { values[f.name] = (e.target as HTMLInputElement).checked; onSliderChange() }"
-        />
-        <span class="field-label" :title="f.description">{{ f.name.replace(/_/g, ' ') }}</span>
-      </label>
-
-      <!-- Numeric fields (range sliders) -->
-      <div v-for="f in numericFields" :key="f.name" class="slider-field">
-        <div class="field-header">
-          <span class="field-label" :title="f.description">{{ f.name.replace(/^edge_/, '').replace(/_/g, ' ') }}</span>
-          <span class="field-value">{{ values[f.name] }}</span>
-        </div>
-        <input
-          type="range"
-          :min="f.min ?? 0"
-          :max="f.max ?? 500"
-          :step="f.type === 'float' ? 0.01 : 1"
-          :value="values[f.name] as number"
-          @input="(e) => { values[f.name] = Number((e.target as HTMLInputElement).value); onSliderChange() }"
-        />
-        <div class="field-range">
-          <span>{{ f.min ?? 0 }}</span>
-          <span>{{ f.max ?? 500 }}</span>
-        </div>
-      </div>
+      <ParameterEditor
+        :fields="fields"
+        :values="values"
+        @update="onFieldUpdate"
+        @reset="resetDefaults"
+      />
     </div>
 
-    <!-- Footer -->
     <div class="sliders-footer">
-      <button
-        class="apply-btn"
-        :disabled="loading || autoApply"
-        @click="applyDetection"
-      >
+      <button class="apply-btn" :disabled="loading || autoApply" @click="applyDetection">
         {{ loading ? 'Running...' : 'Apply' }}
       </button>
       <label class="auto-apply-toggle">
@@ -411,79 +339,6 @@ async function runServer() {
   overflow-y: auto;
 }
 
-.slider-field {
-  display: flex;
-  flex-direction: column;
-  gap: 2px;
-}
-
-.bool-field {
-  flex-direction: row;
-  align-items: center;
-  gap: 6px;
-  cursor: pointer;
-}
-
-.field-header {
-  display: flex;
-  justify-content: space-between;
-  align-items: center;
-}
-
-.field-label {
-  color: var(--text-secondary);
-  font-size: 10px;
-  text-transform: capitalize;
-}
-
-.field-value {
-  font-weight: 600;
-  font-size: 10px;
-  color: var(--text-primary);
-  min-width: 30px;
-  text-align: right;
-}
-
-.field-range {
-  display: flex;
-  justify-content: space-between;
-  font-size: 9px;
-  color: var(--text-dim);
-}
-
-input[type="range"] {
-  -webkit-appearance: none;
-  appearance: none;
-  width: 100%;
-  height: 4px;
-  background: var(--surface-3);
-  border-radius: 2px;
-  outline: none;
-}
-
-input[type="range"]::-webkit-slider-thumb {
-  -webkit-appearance: none;
-  appearance: none;
-  width: 12px;
-  height: 12px;
-  border-radius: 50%;
-  background: var(--text-primary);
-  cursor: pointer;
-}
-
-input[type="range"]::-moz-range-thumb {
-  width: 12px;
-  height: 12px;
-  border-radius: 50%;
-  background: var(--text-primary);
-  cursor: pointer;
-  border: none;
-}
-
-input[type="checkbox"] {
-  accent-color: #00bcd4;
-}
-
 .sliders-footer {
   display: flex;
   align-items: center;
diff --git a/ui/detection-app/src/composables/useCheckpointLoader.ts b/ui/detection-app/src/composables/useCheckpointLoader.ts
index 2e62058..f14ca6e 100644
--- a/ui/detection-app/src/composables/useCheckpointLoader.ts
+++ b/ui/detection-app/src/composables/useCheckpointLoader.ts
@@ -66,11 +66,13 @@ export function useCheckpointLoader(
     currentFrameRef.value = frame.seq
   }
 
-  const { checkpointStageFor } = useStageRegistry()
+  const { stages, checkpointStageFor } = useStageRegistry()
 
-  // Auto-load checkpoint when entering editor mode
+  // Auto-load checkpoint when entering editor mode.
+  // Also watches stages — the registry fetch is async, so on first load
+  // stages may be empty. When they arrive, re-evaluate.
   watch(
-    () => [pipeline.layoutMode, pipeline.editorStage, jobId.value] as const,
+    () => [pipeline.layoutMode, pipeline.editorStage, jobId.value, stages.value.length] as const,
     ([mode, stage, job]) => {
       if (mode === 'bbox_editor' && stage && job) {
         const cpStage = checkpointStageFor(stage)
diff --git a/ui/framework/src/components/ParameterEditor.vue b/ui/framework/src/components/ParameterEditor.vue
new file mode 100644
index 0000000..0ae625e
--- /dev/null
+++ b/ui/framework/src/components/ParameterEditor.vue
@@ -0,0 +1,145 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+
+export interface ConfigField {
+  name: string
+  type: string
+  default: unknown
+  description: string
+  min: number | null
+  max: number | null
+  options: string[] | null
+}
+
+const props = defineProps<{
+  fields: ConfigField[]
+  values: Record<string, unknown>
+}>()
+
+const emit = defineEmits<{
+  'update': [name: string, value: unknown]
+  'reset': []
+}>()
+
+const numericFields = computed(() => props.fields.filter(f => f.type === 'int' || f.type === 'float'))
+const boolFields = computed(() => props.fields.filter(f => f.type === 'bool'))
+
+function onInput(name: string, value: unknown) {
+  emit('update', name, value)
+}
+</script>
+
+<template>
+  <div class="param-editor">
+    <!-- Boolean fields -->
+    <label v-for="f in boolFields" :key="f.name" class="param-field bool-field">
+      <input
+        type="checkbox"
+        :checked="!!values[f.name]"
+        @change="(e) => onInput(f.name, (e.target as HTMLInputElement).checked)"
+      />
+      <span class="field-label" :title="f.description">{{ f.name.replace(/_/g, ' ') }}</span>
+    </label>
+
+    <!-- Numeric fields (range sliders) -->
+    <div v-for="f in numericFields" :key="f.name" class="param-field">
+      <div class="field-header">
+        <span class="field-label" :title="f.description">{{ f.name.replace(/^edge_/, '').replace(/_/g, ' ') }}</span>
+        <span class="field-value">{{ values[f.name] }}</span>
+      </div>
+      <input
+        type="range"
+        :min="f.min ?? 0"
+        :max="f.max ?? 500"
+        :step="f.type === 'float' ? 0.01 : 1"
+        :value="values[f.name] as number"
+        @input="(e) => onInput(f.name, Number((e.target as HTMLInputElement).value))"
+      />
+      <div class="field-range">
+        <span>{{ f.min ?? 0 }}</span>
+        <span>{{ f.max ?? 500 }}</span>
+      </div>
+    </div>
+  </div>
+</template>
+
+<style scoped>
+.param-editor {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-2);
+}
+
+.param-field {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+
+.bool-field {
+  flex-direction: row;
+  align-items: center;
+  gap: 6px;
+  cursor: pointer;
+}
+
+.field-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.field-label {
+  color: var(--text-secondary);
+  font-size: 10px;
+  text-transform: capitalize;
+}
+
+.field-value {
+  font-weight: 600;
+  font-size: 10px;
+  color: var(--text-primary);
+  min-width: 30px;
+  text-align: right;
+}
+
+.field-range {
+  display: flex;
+  justify-content: space-between;
+  font-size: 9px;
+  color: var(--text-dim);
+}
+
+input[type="range"] {
+  -webkit-appearance: none;
+  appearance: none;
+  width: 100%;
+  height: 4px;
+  background: var(--surface-3);
+  border-radius: 2px;
+  outline: none;
+}
+
+input[type="range"]::-webkit-slider-thumb {
+  -webkit-appearance: none;
+  appearance: none;
+  width: 12px;
+  height: 12px;
+  border-radius: 50%;
+  background: var(--text-primary);
+  cursor: pointer;
+}
+
+input[type="range"]::-moz-range-thumb {
+  width: 12px;
+  height: 12px;
+  border-radius: 50%;
+  background: var(--text-primary);
+  cursor: pointer;
+  border: none;
+}
+
+input[type="checkbox"] {
+  accent-color: #00bcd4;
+}
+</style>
diff --git a/ui/framework/src/components/SplitPane.vue b/ui/framework/src/components/SplitPane.vue
index af77b73..7a1b0f4 100644
--- a/ui/framework/src/components/SplitPane.vue
+++ b/ui/framework/src/components/SplitPane.vue
@@ -64,9 +64,11 @@ const isHorizontal = computed(() => props.direction === 'horizontal')
 
 const sizedStyle = computed(() => {
   if (props.sizeMode === 'px') {
+    const sizeStr = size.value + 'px'
+    const minStr = props.min + 'px'
     return isHorizontal.value
-      ? { width: size.value + 'px', flexShrink: '0' }
-      : { height: size.value + 'px', flexShrink: '0' }
+      ? { width: sizeStr, minWidth: minStr, flexShrink: '0' }
+      : { height: sizeStr, minHeight: minStr, flexShrink: '0' }
   }
   return { flex: String(size.value) }
 })
diff --git a/ui/framework/src/composables/useEditorExecution.ts b/ui/framework/src/composables/useEditorExecution.ts
new file mode 100644
index 0000000..e968408
--- /dev/null
+++ b/ui/framework/src/composables/useEditorExecution.ts
@@ -0,0 +1,57 @@
+import { ref } from 'vue'
+
+export interface EditorExecutionOptions {
+  /** Debounce delay in ms for auto-apply. Default: 150 */
+  debounceMs?: number
+}
+
+/**
+ * Generic editor execution pattern — debounced apply with auto-apply toggle,
+ * loading/error/timing state tracking.
+ *
+ * The caller provides the actual execution function. This composable handles
+ * the orchestration: debounce, auto-apply, loading state, timing.
+ */
+export function useEditorExecution(
+  executeFn: () => Promise<void>,
+  options: EditorExecutionOptions = {},
+) {
+  const debounceMs = options.debounceMs ?? 150
+
+  const loading = ref(false)
+  const error = ref<string | null>(null)
+  const autoApply = ref(true)
+  const execTimeMs = ref<number | null>(null)
+
+  let debounceTimer: ReturnType<typeof setTimeout> | null = null
+
+  async function apply() {
+    loading.value = true
+    error.value = null
+    execTimeMs.value = null
+    const t0 = performance.now()
+    try {
+      await executeFn()
+      execTimeMs.value = Math.round(performance.now() - t0)
+    } catch (e) {
+      error.value = String(e)
+    } finally {
+      loading.value = false
+    }
+  }
+
+  function onParameterChange() {
+    if (!autoApply.value) return
+    if (debounceTimer) clearTimeout(debounceTimer)
+    debounceTimer = setTimeout(() => apply(), debounceMs)
+  }
+
+  return {
+    loading,
+    error,
+    autoApply,
+    execTimeMs,
+    apply,
+    onParameterChange,
+  }
+}
diff --git a/ui/framework/src/index.ts b/ui/framework/src/index.ts
index ddcaa5f..8d97ff1 100644
--- a/ui/framework/src/index.ts
+++ b/ui/framework/src/index.ts
@@ -4,12 +4,16 @@ export { SSEDataSource } from './datasources/SSEDataSource'
 export { StaticDataSource } from './datasources/StaticDataSource'
 export { useDataSource } from './composables/useDataSource'
 export { useRegistry } from './composables/useRegistry'
+export { useEditorExecution } from './composables/useEditorExecution'
+export type { EditorExecutionOptions } from './composables/useEditorExecution'
 
 // Components
 export { default as Panel } from './components/Panel.vue'
 export { default as LayoutGrid } from './components/LayoutGrid.vue'
 export { default as ResizeHandle } from './components/ResizeHandle.vue'
 export { default as SplitPane } from './components/SplitPane.vue'
+export { default as ParameterEditor } from './components/ParameterEditor.vue'
+export type { ConfigField } from './components/ParameterEditor.vue'
 
 // Renderers
 export { default as LogRenderer } from './renderers/LogRenderer.vue'