diff --git a/apps/sim/lib/copilot/tools/server/workflow/edit-workflow/builders.ts b/apps/sim/lib/copilot/tools/server/workflow/edit-workflow/builders.ts
index 529a0bc780..9d87c14b26 100644
--- a/apps/sim/lib/copilot/tools/server/workflow/edit-workflow/builders.ts
+++ b/apps/sim/lib/copilot/tools/server/workflow/edit-workflow/builders.ts
@@ -2,7 +2,11 @@ import crypto from 'crypto'
 import { createLogger } from '@sim/logger'
 import type { PermissionGroupConfig } from '@/lib/permission-groups/types'
 import { getEffectiveBlockOutputs } from '@/lib/workflows/blocks/block-outputs'
-import { buildCanonicalIndex, isCanonicalPair } from '@/lib/workflows/subblocks/visibility'
+import {
+  buildCanonicalIndex,
+  buildDefaultCanonicalModes,
+  isCanonicalPair,
+} from '@/lib/workflows/subblocks/visibility'
 import { hasTriggerCapability } from '@/lib/workflows/triggers/trigger-utils'
 import { getAllBlocks } from '@/blocks/registry'
 import type { BlockConfig } from '@/blocks/types'
@@ -130,6 +134,12 @@ export function createBlockFromParams(
       }
     })
 
+    const defaultModes = buildDefaultCanonicalModes(blockConfig.subBlocks)
+    if (Object.keys(defaultModes).length > 0) {
+      if (!blockState.data) blockState.data = {}
+      blockState.data.canonicalModes = defaultModes
+    }
+
     if (validatedInputs) {
       updateCanonicalModesForInputs(blockState, Object.keys(validatedInputs), blockConfig)
     }
diff --git a/apps/sim/lib/workflows/subblocks/visibility.ts b/apps/sim/lib/workflows/subblocks/visibility.ts
index 1ce0076b44..aab03ca5db 100644
--- a/apps/sim/lib/workflows/subblocks/visibility.ts
+++ b/apps/sim/lib/workflows/subblocks/visibility.ts
@@ -75,6 +75,23 @@ export function isCanonicalPair(group?: CanonicalGroup): boolean {
   return Boolean(group?.basicId && group?.advancedIds?.length)
 }
 
+/**
+ * Builds default canonical mode overrides for a block's subblocks.
+ * All canonical pairs default to `'basic'`.
+ */
+export function buildDefaultCanonicalModes(
+  subBlocks: SubBlockConfig[]
+): Record<string, 'basic' | 'advanced'> {
+  const index = buildCanonicalIndex(subBlocks)
+  const modes: Record<string, 'basic' | 'advanced'> = {}
+  for (const group of Object.values(index.groupsById)) {
+    if (isCanonicalPair(group)) {
+      modes[group.canonicalId] = 'basic'
+    }
+  }
+  return modes
+}
+
 /**
  * Determine the active mode for a canonical group.
  */
diff --git a/apps/sim/serializer/index.test.ts b/apps/sim/serializer/index.test.ts
index 8b0539144e..dfdf3a7be3 100644
--- a/apps/sim/serializer/index.test.ts
+++ b/apps/sim/serializer/index.test.ts
@@ -683,34 +683,37 @@ describe('Serializer', () => {
       expect(slackBlock?.config.params.username).toBe('bot')
     })
 
-    it.concurrent('should fall back to legacy advancedMode when canonicalModes not set', () => {
-      const serializer = new Serializer()
+    it.concurrent(
+      'should fall back to legacy advancedMode for non-credential canonical groups when canonicalModes not set',
+      () => {
+        const serializer = new Serializer()
 
-      const block: any = {
-        id: 'slack-1',
-        type: 'slack',
-        name: 'Test Slack Block',
-        position: { x: 0, y: 0 },
-        advancedMode: true,
-        subBlocks: {
-          operation: { value: 'send' },
-          destinationType: { value: 'channel' },
-          channel: { value: 'general' },
-          manualChannel: { value: 'C1234567890' },
-          text: { value: 'Hello world' },
-          username: { value: 'bot' },
-        },
-        outputs: {},
-        enabled: true,
-      }
+        const block: any = {
+          id: 'slack-1',
+          type: 'slack',
+          name: 'Test Slack Block',
+          position: { x: 0, y: 0 },
+          advancedMode: true,
+          subBlocks: {
+            operation: { value: 'send' },
+            destinationType: { value: 'channel' },
+            channel: { value: 'general' },
+            manualChannel: { value: 'C1234567890' },
+            text: { value: 'Hello world' },
+            username: { value: 'bot' },
+          },
+          outputs: {},
+          enabled: true,
+        }
 
-      const serialized = serializer.serializeWorkflow({ 'slack-1': block }, [], {})
-      const slackBlock = serialized.blocks.find((b) => b.id === 'slack-1')
+        const serialized = serializer.serializeWorkflow({ 'slack-1': block }, [], {})
+        const slackBlock = serialized.blocks.find((b) => b.id === 'slack-1')
 
-      expect(slackBlock).toBeDefined()
-      expect(slackBlock?.config.params.channel).toBe('C1234567890')
-      expect(slackBlock?.config.params.manualChannel).toBeUndefined()
-    })
+        expect(slackBlock).toBeDefined()
+        expect(slackBlock?.config.params.channel).toBe('C1234567890')
+        expect(slackBlock?.config.params.manualChannel).toBeUndefined()
+      }
+    )
 
     it.concurrent('should use basic value by default when no mode specified', () => {
       const serializer = new Serializer()
diff --git a/apps/sim/serializer/index.ts b/apps/sim/serializer/index.ts
index 6626468dd0..671535ef68 100644
--- a/apps/sim/serializer/index.ts
+++ b/apps/sim/serializer/index.ts
@@ -61,8 +61,9 @@ function shouldSerializeSubBlock(
     const group = canonicalId ? canonicalIndex.groupsById[canonicalId] : undefined
     if (group && isCanonicalPair(group)) {
       const mode =
-        canonicalModeOverrides?.[group.canonicalId] ??
-        (displayAdvancedOptions ? 'advanced' : resolveCanonicalMode(group, values))
+        canonicalModeOverrides?.[group.canonicalId] != null || !displayAdvancedOptions
+          ? resolveCanonicalMode(group, values, canonicalModeOverrides)
+          : 'advanced'
       const matchesMode =
         mode === 'advanced'
           ? group.advancedIds.includes(subBlockConfig.id)
@@ -374,8 +375,11 @@ export class Serializer {
 
     Object.values(canonicalIndex.groupsById).forEach((group) => {
       const { basicValue, advancedValue } = getCanonicalValues(group, params)
+      const hasExplicitOverride = canonicalModeOverrides?.[group.canonicalId] != null
       const pairMode =
-        canonicalModeOverrides?.[group.canonicalId] ?? (legacyAdvancedMode ? 'advanced' : 'basic')
+        hasExplicitOverride || !legacyAdvancedMode
+          ? resolveCanonicalMode(group, allValues, canonicalModeOverrides)
+          : 'advanced'
       const chosen = pairMode === 'advanced' ? advancedValue : basicValue
 
       const sourceIds = [group.basicId, ...group.advancedIds].filter(Boolean) as string[]
diff --git a/apps/sim/stores/workflows/utils.ts b/apps/sim/stores/workflows/utils.ts
index 89b6c9eea3..1352db5d10 100644
--- a/apps/sim/stores/workflows/utils.ts
+++ b/apps/sim/stores/workflows/utils.ts
@@ -3,6 +3,7 @@ import { v4 as uuidv4 } from 'uuid'
 import { DEFAULT_DUPLICATE_OFFSET } from '@/lib/workflows/autolayout/constants'
 import { getEffectiveBlockOutputs } from '@/lib/workflows/blocks/block-outputs'
 import { mergeSubblockStateWithValues } from '@/lib/workflows/subblocks'
+import { buildDefaultCanonicalModes } from '@/lib/workflows/subblocks/visibility'
 import { hasTriggerCapability } from '@/lib/workflows/triggers/trigger-utils'
 import { TriggerUtils } from '@/lib/workflows/triggers/triggers'
 import { getBlock } from '@/blocks'
@@ -196,6 +197,13 @@ export function prepareBlockState(options: PrepareBlockStateOptions): BlockState
     preferToolOutputs: !effectiveTriggerMode,
   })
 
+  if (blockConfig.subBlocks) {
+    const canonicalModes = buildDefaultCanonicalModes(blockConfig.subBlocks)
+    if (Object.keys(canonicalModes).length > 0) {
+      blockData.canonicalModes = canonicalModes
+    }
+  }
+
   return {
     id,
     type,