diff --git a/src/common/beam/BeamView.tsx b/src/common/beam/BeamView.tsx
index cc026f9c0..99dac24e9 100644
--- a/src/common/beam/BeamView.tsx
+++ b/src/common/beam/BeamView.tsx
@@ -29,7 +29,7 @@ export function BeamView(props: {
   const {
     /* root */ editInputHistoryMessage,
     /* scatter */ setRayCount, startScatteringAll, stopScatteringAll,
-    /* gather */ setFusionIndex, setFusionLlmId, startFusion, stopFusion,
+    /* gather */ setFusionIndex, setFusionLlmId, fusionCustomize, fusionStart, fusionStop,
   } = props.beamStore.getState();
   const {
     /* root */ inputHistory, inputIssues, inputReady,
@@ -140,8 +140,9 @@ export function BeamView(props: {
           isMobile={props.isMobile}
           fusionIndex={fusionIndex}
           setFusionIndex={setFusionIndex}
-          onStartFusion={startFusion}
-          onStopFusion={stopFusion}
+          onFusionCustomize={fusionCustomize}
+          onFusionStart={fusionStart}
+          onFusionStop={fusionStop}
         />
 
         {/* Fusion Output */}
diff --git a/src/common/beam/gather/BeamGatherConfig.tsx b/src/common/beam/gather/BeamGatherConfig.tsx
index 25595fb2d..e67dc88ca 100644
--- a/src/common/beam/gather/BeamGatherConfig.tsx
+++ b/src/common/beam/gather/BeamGatherConfig.tsx
@@ -6,8 +6,10 @@ import { Box, Typography } from '@mui/joy';
 import { ChatMessageMemo } from '../../../apps/chat/components/message/ChatMessage';
 
 import { createDMessage } from '~/common/state/store-chats';
-import { BeamStoreApi, useBeamStore } from '~/common/beam/store-beam.hooks';
-import { GATHER_DEBUG_NONCUSTOM } from '~/common/beam/beam.config';
+
+import type { TInstruction } from './beam.gather';
+import { BeamStoreApi, useBeamStore } from '../store-beam.hooks';
+import { GATHER_DEBUG_NONCUSTOM } from '../beam.config';
 
 
 const gatherConfigWrapperSx: SxProps = {
@@ -34,6 +36,79 @@ const configChatInstructionSx: SxProps = {
   flex: 1,
 };
 
+function InstructionWrapper(props: { children: React.ReactNode }) {
+  return (
+    <Box sx={{ display: 'flex', flexDirection: 'column', mx: 'var(--Pad)' }}>
+      {props.children}
+    </Box>
+  );
+}
+
+
+function ReadOnlyInstruction(props: { instruction: TInstruction, isMobile: boolean }) {
+  const { instruction } = props;
+
+  // render 'chat-generate'
+  if (instruction.type === 'chat-generate') {
+    return (
+      <InstructionWrapper>
+        <Box sx={{ display: 'flex', alignItems: 'center' }}>
+          <Typography level='body-xs'>
+            System Prompt:
+          </Typography>
+          <ChatMessageMemo
+            message={createDMessage('assistant', instruction.systemPrompt)}
+            fitScreen={props.isMobile}
+            showAvatar={false}
+            adjustContentScaling={-1}
+            sx={configChatInstructionSx}
+          />
+        </Box>
+        <Box sx={{ display: 'flex', alignItems: 'center' }}>
+          <Typography level='body-xs'>
+            User Prompt:
+          </Typography>
+          <ChatMessageMemo
+            message={createDMessage('assistant', instruction.userPrompt)}
+            fitScreen={props.isMobile}
+            showAvatar={false}
+            adjustContentScaling={-1}
+            sx={configChatInstructionSx}
+          />
+        </Box>
+      </InstructionWrapper>
+    );
+  }
+
+  // render 'user-input-checklist'
+  if (instruction.type === 'user-input-checklist') {
+    return (
+      <InstructionWrapper>
+        <Box sx={{ display: 'flex', alignItems: 'center' }}>
+          <Typography level='body-xs'>
+            Checklist:
+          </Typography>
+          <ChatMessageMemo
+            message={createDMessage('assistant', '#### Test\n- [ ] test\n- [ ] ...')}
+            fitScreen={props.isMobile}
+            showAvatar={false}
+            adjustContentScaling={-1}
+            sx={configChatInstructionSx}
+          />
+        </Box>
+      </InstructionWrapper>
+    );
+  }
+
+  return (
+    <InstructionWrapper>
+      <Typography level='body-xs'>
+        Unknown Instruction
+      </Typography>
+    </InstructionWrapper>
+  );
+}
+
 
 export function BeamGatherConfig(props: {
   beamStore: BeamStoreApi
@@ -41,7 +116,7 @@ export function BeamGatherConfig(props: {
 }) {
 
   // state
-  const [viewInstructionIndex, setViewInstructionIndex] = React.useState(0);
+  // const [viewInstructionIndex, setViewInstructionIndex] = React.useState(0);
 
   // external state
   const fusion = useBeamStore(props.beamStore, store => {
@@ -49,64 +124,23 @@ export function BeamGatherConfig(props: {
     return (fusion?.isEditable || GATHER_DEBUG_NONCUSTOM) ? fusion : null;
   });
 
-
-  // [effect] sync the fusion program index to the viewInstructionIndex
-  React.useEffect(() => {
-    fusion && setViewInstructionIndex(fusion.currentInstructionIndex);
-  }, [fusion]);
-
+  // // [effect] sync the fusion program index to the viewInstructionIndex
+  // React.useEffect(() => {
+  //   fusion && setViewInstructionIndex(fusion.currentInstructionIndex);
+  // }, [fusion]);
 
   // derived state
-  const instruction = React.useMemo(() => {
-    return fusion?.instructions[viewInstructionIndex] ?? null;
-  }, [fusion, viewInstructionIndex]);
+  // const instructions = React.useMemo(() => {
+  //   return fusion?.instructions ?? null;
+  // }, [fusion]);
 
+  const instructions = fusion?.instructions ?? null;
 
-  // render instruction
-  const instructionComponent = React.useMemo(() => {
-    if (instruction && instruction.type === 'chat-generate') {
-      return <>
-        {instruction.systemPrompt && (
-          <Box sx={{ display: 'flex', alignItems: 'center', mx: 'var(--Pad)' }}>
-            <Typography level='body-xs'>
-              System Prompt:
-            </Typography>
-            <ChatMessageMemo
-              message={createDMessage('assistant', instruction.systemPrompt)}
-              fitScreen={props.isMobile}
-              showAvatar={false}
-              adjustContentScaling={-1}
-              sx={configChatInstructionSx}
-            />
-          </Box>
-        )}
-        {instruction.userPrompt && (
-          <Box sx={{ display: 'flex', alignItems: 'center', ml: 'var(--Pad)' }}>
-            <Typography level='body-xs'>
-              User Prompt:
-            </Typography>
-            <ChatMessageMemo
-              message={createDMessage('assistant', instruction.userPrompt)}
-              fitScreen={props.isMobile}
-              showAvatar={false}
-              adjustContentScaling={-1}
-              sx={configChatInstructionSx}
-            />
-
-          </Box>
-        )}
-      </>;
-    }
-    return null;
-  }, [instruction, props.isMobile]);
-
-
-  if (!instructionComponent)
-    return null;
-
-  return (
+  return !!instructions?.length ? (
     <Box sx={gatherConfigWrapperSx}>
-      {instructionComponent}
+      {instructions.map((instruction, stepIndex) =>
+        <ReadOnlyInstruction key={'step-' + stepIndex} instruction={instruction} isMobile={props.isMobile} />,
+      )}
     </Box>
-  );
+  ) : null;
 }
\ No newline at end of file
diff --git a/src/common/beam/gather/BeamGatherPane.tsx b/src/common/beam/gather/BeamGatherPane.tsx
index 4f2e0056f..ac220e608 100644
--- a/src/common/beam/gather/BeamGatherPane.tsx
+++ b/src/common/beam/gather/BeamGatherPane.tsx
@@ -1,9 +1,10 @@
 import * as React from 'react';
 
 import type { SxProps } from '@mui/joy/styles/types';
-import { Box, Button, ButtonGroup, FormControl, SvgIconProps, Typography } from '@mui/joy';
+import { Box, Button, ButtonGroup, FormControl, IconButton, SvgIconProps, Tooltip, Typography } from '@mui/joy';
 import AutoAwesomeIcon from '@mui/icons-material/AutoAwesome';
 import AutoAwesomeOutlinedIcon from '@mui/icons-material/AutoAwesomeOutlined';
+import EditRoundedIcon from '@mui/icons-material/EditRounded';
 import MergeRoundedIcon from '@mui/icons-material/MergeRounded';
 import StopRoundedIcon from '@mui/icons-material/StopRounded';
 
@@ -15,7 +16,7 @@ import { useScrollToBottom } from '~/common/scroll-to-bottom/useScrollToBottom';
 import { GATHER_COLOR } from '../beam.config';
 import { beamPaneSx } from '../BeamCard';
 
-import { FUSION_PROGRAMS } from './beam.gather';
+import { FUSION_FACTORIES } from './beam.gather';
 
 
 const mobileBeamGatherPane: SxProps = {
@@ -47,21 +48,25 @@ export function BeamGatherPane(props: {
   gatherLlmIcon?: React.FunctionComponent<SvgIconProps>,
   fusionIndex: number | null,
   setFusionIndex: (index: number | null) => void
-  onStartFusion: () => void,
-  onStopFusion: () => void,
+  onFusionCustomize: (index: number) => void,
+  onFusionStart: () => void,
+  onFusionStop: () => void,
 }) {
 
   // external state
   const { setStickToBottom } = useScrollToBottom();
 
   // derived state
-  const { gatherCount, gatherEnabled, gatherBusy, setFusionIndex } = props;
+  const { gatherCount, gatherEnabled, gatherBusy, setFusionIndex, onFusionCustomize } = props;
 
   const handleFusionActivate = React.useCallback((idx: number, shiftPressed: boolean) => {
     setStickToBottom(true);
     setFusionIndex((idx !== props.fusionIndex || !shiftPressed) ? idx : null);
   }, [props.fusionIndex, setFusionIndex, setStickToBottom]);
 
+  const handleFusionCustomize = React.useCallback(() => {
+    props.fusionIndex !== null && onFusionCustomize(props.fusionIndex);
+  }, [onFusionCustomize, props.fusionIndex]);
 
   const Icon = props.gatherLlmIcon || (gatherBusy ? AutoAwesomeIcon : AutoAwesomeOutlinedIcon);
 
@@ -85,10 +90,13 @@ export function BeamGatherPane(props: {
 
       {/* Method */}
       <FormControl sx={{ my: '-0.25rem' }}>
-        <FormLabelStart title={<><AutoAwesomeOutlinedIcon sx={{ fontSize: 'md', mr: 0.5 }} />Method</>} sx={{ mb: '0.25rem' /* orig: 6px */ }} />
-        <Box sx={{ display: 'flex', flexAlign: 'center', gap: 1 }}>
+        <FormLabelStart
+          title={<><AutoAwesomeOutlinedIcon sx={{ fontSize: 'md', mr: 0.5 }} />Method</>}
+          sx={{ mb: '0.25rem' /* orig: 6px */ }}
+        />
+        <Box sx={{ display: 'flex', alignItems: 'center', gap: 1 }}>
           <ButtonGroup variant='outlined'>
-            {FUSION_PROGRAMS.map((fusion, idx) => {
+            {FUSION_FACTORIES.map((fusion, idx) => {
               const isActive = idx === props.fusionIndex;
               return (
                 <Button
@@ -108,6 +116,13 @@ export function BeamGatherPane(props: {
               );
             })}
           </ButtonGroup>
+          {(props.fusionIndex !== null) && (
+            <Tooltip disableInteractive title='Customize This Merge'>
+              <IconButton size='sm' color='success' disabled={props.gatherBusy || props.fusionIndex === 2} onClick={handleFusionCustomize}>
+                <EditRoundedIcon />
+              </IconButton>
+            </Tooltip>
+          )}
         </Box>
       </FormControl>
 
@@ -123,7 +138,7 @@ export function BeamGatherPane(props: {
           variant='solid' color={GATHER_COLOR}
           disabled={!gatherEnabled || gatherBusy} loading={gatherBusy}
           endDecorator={<MergeRoundedIcon />}
-          onClick={props.onStartFusion}
+          onClick={props.onFusionStart}
           sx={{ minWidth: 120 }}
         >
           Merge
@@ -133,7 +148,7 @@ export function BeamGatherPane(props: {
           // key='gather-stop'
           variant='solid' color='danger'
           endDecorator={<StopRoundedIcon />}
-          onClick={props.onStopFusion}
+          onClick={props.onFusionStop}
           sx={{ minWidth: 120 }}
         >
           Stop
diff --git a/src/common/beam/gather/beam.gather.ts b/src/common/beam/gather/beam.gather.ts
index af03323b8..d541c43c3 100644
--- a/src/common/beam/gather/beam.gather.ts
+++ b/src/common/beam/gather/beam.gather.ts
@@ -9,45 +9,53 @@ import { GATHER_PLACEHOLDER } from '../beam.config';
 
 // Choose, Improve, Fuse, Manual
 
-export const FUSION_PROGRAMS: { label: string, factory: () => BFusion }[] = [
+const commonInitialization = (isEditable: boolean): Pick<BFusion,
+  'isEditable' | 'currentInstructionIndex' | 'llmId' | 'status' | 'outputMessage'
+> => ({
+  isEditable,
+  currentInstructionIndex: 0,
+  llmId: null,
+  status: 'idle',
+  outputMessage: createDMessage('assistant', GATHER_PLACEHOLDER),
+});
+
+export const FUSION_FACTORIES: { label: string, factory: () => BFusion }[] = [
   {
-    label: 'Guided', factory: () => ({
+    label: 'Guided',
+    factory: () => ({
       instructions: [{
         type: 'chat-generate',
-        systemPrompt: 'You are',
-        userPrompt: 'Perform this',
+        systemPrompt: 'You arfe',
+        userPrompt: 'Perform thiws',
         outputType: 'fin',
+      }, {
+        type: 'user-input-checklist',
       }],
-      currentInstructionIndex: 0,
-      isEditable: false,
-      llmId: null,
-      status: 'idle',
-      outputMessage: createDMessage('assistant', GATHER_PLACEHOLDER),
+      ...commonInitialization(false),
     }),
   },
   {
-    label: 'Fuse', factory: () => ({
+    label: 'Fuse',
+    factory: () => ({
       instructions: [{
         type: 'chat-generate',
         systemPrompt: 'You are an editor',
         userPrompt: 'Best of all',
         outputType: 'fin',
       }],
-      currentInstructionIndex: 0,
-      isEditable: false,
-      llmId: null,
-      status: 'idle',
-      outputMessage: createDMessage('assistant', GATHER_PLACEHOLDER + '2'),
+      ...commonInitialization(false),
     }),
   },
   {
-    label: 'Custom', factory: () => ({
-      instructions: [],
-      currentInstructionIndex: 0,
-      isEditable: true,
-      llmId: null,
-      status: 'idle',
-      outputMessage: createDMessage('assistant', GATHER_PLACEHOLDER + '3'),
+    label: 'Custom',
+    factory: () => ({
+      instructions: [{
+        type: 'chat-generate',
+        systemPrompt: 'You are a custom editor',
+        userPrompt: 'Best of all',
+        outputType: 'fin',
+      }],
+      ...commonInitialization(true),
     }),
   },
 ];
@@ -73,7 +81,7 @@ export function fusionGatherStop(fusion: BFusion): BFusion {
 
 /// Gather Store Slice ///
 
-type TInstruction = {
+export type TInstruction = {
   type: 'chat-generate',
   systemPrompt: string;
   userPrompt: string;
@@ -84,14 +92,14 @@ type TInstruction = {
 
 export interface BFusion {
   // set at creation, adjusted later if this is a custom fusion (and only when idle)
+  isEditable: boolean; // only true on a single custom fusion
   instructions: TInstruction[];
-  currentInstructionIndex: number;
-  isEditable: boolean;
 
-  // set at lifecycle
+  // set at start
   llmId: DLLMId | null;
 
   // variable
+  currentInstructionIndex: number; // points to the next instruction to execute
   status: 'idle' | 'fusing' | 'success' | 'stopped' | 'error';
   outputMessage: DMessage;
   issue?: string;
@@ -115,7 +123,7 @@ export const reInitGatherStateSlice = (prevFusions: BFusion[]): GatherStateSlice
 
   return {
     // recreate all fusions (no recycle)
-    fusions: FUSION_PROGRAMS.map(spec => spec.factory()),
+    fusions: FUSION_FACTORIES.map(spec => spec.factory()),
     fusionIndex: null,
     fusionLlmId: null,
     isGathering: false,
@@ -126,8 +134,12 @@ export interface GatherStoreSlice extends GatherStateSlice {
 
   setFusionIndex: (index: number | null) => void;
   setFusionLlmId: (llmId: DLLMId | null) => void;
-  startFusion: () => void;
-  stopFusion: () => void;
+
+  fusionCustomize: (sourceIndex: number) => void;
+  fusionStart: () => void;
+  fusionStop: () => void;
+
+  _fusionUpdate: (fusionIndex: number, update: Partial<BFusion> | ((fusion: BFusion) => (Partial<BFusion> | null))) => void;
 
 }
 
@@ -147,12 +159,37 @@ export const createGatherSlice: StateCreator<GatherStoreSlice, [], [], GatherSto
       fusionLlmId: llmId,
     }),
 
-  startFusion: () => {
+  fusionCustomize: (sourceIndex: number) => {
+    const { fusions, setFusionIndex, _fusionUpdate } = _get();
+    const editableFusionIndex = fusions.findIndex(fusion => fusion.isEditable);
+    const fusionFactory = FUSION_FACTORIES[sourceIndex];
+    if (editableFusionIndex === -1 || editableFusionIndex === sourceIndex || !fusionFactory)
+      return;
+    _fusionUpdate(editableFusionIndex, customFusion => {
+      // Terminate current custom fusion, if any
+      fusionGatherStop(customFusion);
+      return {
+        ...fusionFactory.factory(),
+        isEditable: true,
+      };
+    });
+    setFusionIndex(editableFusionIndex);
+  },
+
+  fusionStart: () => {
     console.log('startGatheringCurrent');
   },
 
-  stopFusion: () => {
+  fusionStop: () => {
     console.log('stopGatheringCurrent');
   },
 
+  _fusionUpdate: (fusionIndex: number, update: Partial<BFusion> | ((fusion: BFusion) => (Partial<BFusion> | null))) =>
+    _set(state => ({
+      fusions: state.fusions.map((fusion, index) => (index === fusionIndex)
+        ? { ...fusion, ...(typeof update === 'function' ? update(fusion) : update) }
+        : fusion,
+      ),
+    })),
+
 });
diff --git a/src/common/beam/scatter/beam.scatter.ts b/src/common/beam/scatter/beam.scatter.ts
index 700fbe322..cbf96e7ee 100644
--- a/src/common/beam/scatter/beam.scatter.ts
+++ b/src/common/beam/scatter/beam.scatter.ts
@@ -264,12 +264,13 @@ export const createScatterSlice: StateCreator<RootStoreSlice & GatherStoreSlice
       scatterLlmId: llmId,
     }),
 
-  _rayUpdate: (rayId: BRayId, update: Partial<BRay> | ((ray: BRay) => Partial<BRay>)) => _set(state => ({
-    rays: state.rays.map(ray => (ray.rayId === rayId)
-      ? { ...ray, ...(typeof update === 'function' ? update(ray) : update) }
-      : ray,
-    ),
-  })),
+  _rayUpdate: (rayId: BRayId, update: Partial<BRay> | ((ray: BRay) => Partial<BRay>)) =>
+    _set(state => ({
+      rays: state.rays.map(ray => (ray.rayId === rayId)
+        ? { ...ray, ...(typeof update === 'function' ? update(ray) : update) }
+        : ray,
+      ),
+    })),
 
 
   syncRaysStateToBeam: () => {