diff --git a/packages/ui/src/components/message-block.tsx b/packages/ui/src/components/message-block.tsx
index ac8497f73..cad75773c 100644
--- a/packages/ui/src/components/message-block.tsx
+++ b/packages/ui/src/components/message-block.tsx
@@ -298,6 +298,7 @@ interface MessageContentItemProps {
   showDeleteMessage?: boolean
   onDeleteHoverChange?: (state: DeleteHoverState) => void
   selectedMessageIds?: () => Set<string>
+  selectedToolPartKeys?: () => Set<string>
   onToggleSelectedMessage?: (messageId: string, selected: boolean) => void
 }
 
@@ -396,6 +397,7 @@ function MessageContentItem(props: MessageContentItemProps) {
           showDeleteMessage={props.showDeleteMessage}
           onDeleteHoverChange={props.onDeleteHoverChange}
           selectedMessageIds={props.selectedMessageIds}
+          selectedToolPartKeys={props.selectedToolPartKeys}
           onToggleSelectedMessage={props.onToggleSelectedMessage}
           onRevert={props.onRevert}
           onDeleteMessagesUpTo={props.onDeleteMessagesUpTo}
@@ -756,11 +758,6 @@ export default function MessageBlock(props: MessageBlockProps) {
   const isDeleteMessageHovered = () => {
     const hover = props.deleteHover?.() ?? ({ kind: "none" } as DeleteHoverState)
 
-    const selected = props.selectedMessageIds?.() ?? new Set<string>()
-    if (selected.has(props.messageId)) {
-      return true
-    }
-
     if (hover.kind === "message") {
       return hover.messageId === props.messageId
     }
@@ -1111,6 +1108,7 @@ export default function MessageBlock(props: MessageBlockProps) {
                     onDeleteHoverChange={props.onDeleteHoverChange}
                     onDeleteMessagesUpTo={props.onDeleteMessagesUpTo}
                     selectedMessageIds={props.selectedMessageIds}
+                    selectedToolPartKeys={props.selectedToolPartKeys}
                     onToggleSelectedMessage={props.onToggleSelectedMessage}
                     onContentRendered={props.onContentRendered}
                     forceExpanded={activeSearchMatch()?.partId === (item() as ReasoningDisplayItem).partId}
@@ -1302,7 +1300,7 @@ function StepCard(props: StepCardProps) {
     }
     const info = props.messageInfo
     const part = props.part as any
-    
+
     // step-finish parts have tokens embedded; also check messageInfo
     const partTokens = part?.tokens
     const infoTokens = info && info.role === "assistant" ? info.tokens : undefined
@@ -1310,7 +1308,7 @@ function StepCard(props: StepCardProps) {
     if (!tokens) {
       return null
     }
-    
+
     return {
       input: tokens.input ?? 0,
       output: tokens.output ?? 0,
@@ -1507,6 +1505,7 @@ interface ReasoningCardProps {
   onDeleteHoverChange?: (state: DeleteHoverState) => void
   onDeleteMessagesUpTo?: (messageId: string) => void | Promise<void>
   selectedMessageIds?: () => Set<string>
+  selectedToolPartKeys?: () => Set<string>
   onToggleSelectedMessage?: (messageId: string, selected: boolean) => void
   onContentRendered?: () => void
   forceExpanded?: boolean
@@ -1585,7 +1584,16 @@ function ReasoningCard(props: ReasoningCardProps) {
   const [deletingMessage, setDeletingMessage] = createSignal(false)
   const [deletingUpTo, setDeletingUpTo] = createSignal(false)
   const [scrollTopSnapshot, setScrollTopSnapshot] = createSignal(0)
-  const isSelectedForDeletion = () => Boolean(props.selectedMessageIds?.().has(props.messageId))
+  const isSelectedForDeletion = () => {
+    if (props.selectedMessageIds?.().has(props.messageId)) return true
+    const toolKeys = props.selectedToolPartKeys?.()
+    if (!toolKeys || toolKeys.size === 0) return false
+    const prefix = `${props.messageId}:`
+    for (const key of toolKeys) {
+      if (key.startsWith(prefix)) return true
+    }
+    return false
+  }
 
   createEffect(() => {
     setExpanded(Boolean(props.defaultExpanded))
@@ -1766,6 +1774,7 @@ function ReasoningCard(props: ReasoningCardProps) {
   return (
     <div
       class="delete-hover-scope message-reasoning-card"
+      data-delete-part-hover={isSelectedForDeletion() ? "true" : undefined}
       data-part-id={typeof (props.part as any)?.id === "string" ? (props.part as any).id : undefined}
     >
       <div class="message-reasoning-header">
diff --git a/packages/ui/src/components/message-item.tsx b/packages/ui/src/components/message-item.tsx
index d0f60386c..36d738f61 100644
--- a/packages/ui/src/components/message-item.tsx
+++ b/packages/ui/src/components/message-item.tsx
@@ -33,6 +33,7 @@ interface MessageItemProps {
   parts: ClientPart[]
   onRevert?: (messageId: string) => void
   selectedMessageIds?: () => Set<string>
+  selectedToolPartKeys?: () => Set<string>
   onToggleSelectedMessage?: (messageId: string, selected: boolean) => void
   onDeleteMessagesUpTo?: (messageId: string) => void | Promise<void>
   onFork?: (messageId?: string) => void
@@ -99,7 +100,16 @@ export default function MessageItem(props: MessageItemProps) {
     })
   })
 
-  const isSelectedForDeletion = () => Boolean(props.selectedMessageIds?.().has(props.record.id))
+  const isSelectedForDeletion = () => {
+    if (props.selectedMessageIds?.().has(props.record.id)) return true
+    const toolKeys = props.selectedToolPartKeys?.()
+    if (!toolKeys || toolKeys.size === 0) return false
+    const prefix = `${props.record.id}:`
+    for (const key of toolKeys) {
+      if (key.startsWith(prefix)) return true
+    }
+    return false
+  }
 
   let topRowEl: HTMLDivElement | undefined
   let actionsEl: HTMLDivElement | undefined
@@ -468,7 +478,10 @@ export default function MessageItem(props: MessageItemProps) {
       data-message-role={isUser() ? "user" : "assistant"}
       data-message-status={props.record.status}
     >
-      <header class={`message-item-header ${isUser() ? "pb-0.5" : "pb-0"}`}>
+      <header
+        class={`message-item-header ${isUser() ? "pb-0.5" : "pb-0"} delete-hover-scope`}
+        data-delete-part-hover={isSelectedForDeletion() ? "true" : undefined}
+      >
         <div class="message-item-header-row message-item-header-row--top" ref={(el) => (topRowEl = el)}>
           <div class="message-header-left">
             <div class="message-speaker-primary" ref={(el) => (speakerPrimaryEl = el)}>
diff --git a/packages/ui/src/components/message-section.tsx b/packages/ui/src/components/message-section.tsx
index 8efe06106..c55a68938 100644
--- a/packages/ui/src/components/message-section.tsx
+++ b/packages/ui/src/components/message-section.tsx
@@ -614,6 +614,17 @@ export default function MessageSection(props: MessageSectionProps) {
 
     const allowed = deletableMessageIds()
 
+    const toolPartsByMessage = new Map<string, Set<string>>()
+    for (const entry of toolParts) {
+      if (!allowed.has(entry.messageId)) continue
+      let ids = toolPartsByMessage.get(entry.messageId)
+      if (!ids) {
+        ids = new Set<string>()
+        toolPartsByMessage.set(entry.messageId, ids)
+      }
+      ids.add(entry.partId)
+    }
+
     const idsInSessionOrder = messageIds()
     const toDelete: string[] = []
     for (let idx = idsInSessionOrder.length - 1; idx >= 0; idx -= 1) {
@@ -623,6 +634,37 @@ export default function MessageSection(props: MessageSectionProps) {
       }
     }
 
+    const stepFinishPartsToDelete: { messageId: string; partId: string }[] = []
+    const reasoningPartsToDelete: { messageId: string; partId: string }[] = []
+    if (toolPartsByMessage.size > 0) {
+      const s = store()
+      for (const [messageId, selectedToolPartIds] of toolPartsByMessage.entries()) {
+        if (selected.has(messageId)) continue
+        const record = s.getMessage(messageId)
+        if (!record) continue
+        const stepFinishPartIds: string[] = []
+        const reasoningPartIds: string[] = []
+        for (const partId of record.partIds ?? []) {
+          const partRecord = record.parts?.[partId]
+          const part = partRecord?.data
+          if (!part) continue
+          if (part.type === "step-finish") {
+            stepFinishPartIds.push(partId)
+          }
+          if (part.type === "reasoning") {
+            reasoningPartIds.push(partId)
+          }
+        }
+        if (selectedToolPartIds.size === 0) continue
+        for (const partId of stepFinishPartIds) {
+          stepFinishPartsToDelete.push({ messageId, partId })
+        }
+        for (const partId of reasoningPartIds) {
+          reasoningPartsToDelete.push({ messageId, partId })
+        }
+      }
+    }
+
     try {
       for (const messageId of toDelete) {
         await deleteMessage(props.instanceId, props.sessionId, messageId)
@@ -631,6 +673,14 @@ export default function MessageSection(props: MessageSectionProps) {
         if (!allowed.has(messageId)) continue
         await deleteMessagePart(props.instanceId, props.sessionId, messageId, partId)
       }
+      for (const { messageId, partId } of stepFinishPartsToDelete) {
+        if (!allowed.has(messageId)) continue
+        await deleteMessagePart(props.instanceId, props.sessionId, messageId, partId)
+      }
+      for (const { messageId, partId } of reasoningPartsToDelete) {
+        if (!allowed.has(messageId)) continue
+        await deleteMessagePart(props.instanceId, props.sessionId, messageId, partId)
+      }
       clearDeleteMode()
     } catch (error) {
       showAlertDialog(t("messageSection.bulkDelete.failedMessage"), {
diff --git a/packages/ui/src/styles/messaging/delete-overlays.css b/packages/ui/src/styles/messaging/delete-overlays.css
index 344c8a1ed..c38b485b9 100644
--- a/packages/ui/src/styles/messaging/delete-overlays.css
+++ b/packages/ui/src/styles/messaging/delete-overlays.css
@@ -26,10 +26,16 @@
 .delete-hover-scope[data-delete-part-hover="true"]::before {
   content: "";
   position: absolute;
-  inset: -2px;
+  inset: -4px;
   background: var(--status-error-bg);
   border-radius: 0;
   pointer-events: none;
   /* Overlay must sit above the part card background. */
   z-index: 10;
 }
+
+
+
+.message-reasoning-card[data-delete-part-hover="true"]::before {
+  inset: 0;
+}