From cf34cd2c94992358b7998df418848e110ed4c179 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 12 Sep 2026 20:15:18 -0700
Subject: [PATCH 1/3] feat(copilot): show model-authored tool activity

---
 .../hero-chat-loop/hero-tool-call-item.tsx    |   3 +-
 .../agent-group/agent-group-view.tsx          |   9 +-
 .../agent-group/agent-group.test.ts           |  39 ++++++-
 .../agent-group/tool-activity-group.tsx       |   7 +-
 .../agent-group/tool-call-item.test.tsx       |  83 ++++++++++++++
 .../components/agent-group/tool-call-item.tsx |  11 +-
 .../message-content/message-content.test.ts   |  27 +++++
 .../message-content/message-content.tsx       |  10 +-
 .../hooks/stream/turn-model-serialize.test.ts | 101 ++++++++++++++++++
 .../home/hooks/stream/turn-model-serialize.ts |   7 +-
 .../home/hooks/stream/turn-model.ts           |  10 +-
 .../[workspaceId]/home/hooks/use-chat.ts      |   6 ++
 .../app/workspace/[workspaceId]/home/types.ts |   3 +
 apps/sim/lib/api/contracts/copilot.ts         |   1 +
 apps/sim/lib/copilot/chat/display-message.ts  |   3 +
 .../copilot/chat/effective-transcript.test.ts |  64 +++++++++++
 .../lib/copilot/chat/effective-transcript.ts  |  24 +++--
 .../copilot/chat/persisted-message.test.ts    |  81 ++++++++++++++
 .../sim/lib/copilot/chat/persisted-message.ts |  11 ++
 .../generated/mothership-stream-v1-schema.ts  |   4 +
 .../copilot/generated/mothership-stream-v1.ts |   1 +
 .../copilot/request/handlers/handlers.test.ts |  85 +++++++++++++++
 apps/sim/lib/copilot/request/handlers/tool.ts |  39 +++++--
 apps/sim/lib/copilot/request/types.ts         |   2 +
 .../lib/copilot/tools/tool-display.test.ts    |  27 +++++
 apps/sim/lib/copilot/tools/tool-display.ts    |  35 ++++--
 26 files changed, 659 insertions(+), 34 deletions(-)

diff --git a/apps/sim/app/(landing)/components/hero/components/hero-chat-loop/hero-tool-call-item.tsx b/apps/sim/app/(landing)/components/hero/components/hero-chat-loop/hero-tool-call-item.tsx
index b659eae8b45..f32b4385062 100644
--- a/apps/sim/app/(landing)/components/hero/components/hero-chat-loop/hero-tool-call-item.tsx
+++ b/apps/sim/app/(landing)/components/hero/components/hero-chat-loop/hero-tool-call-item.tsx
@@ -11,6 +11,7 @@ export function HeroToolCallItem({
   renderStatus,
   toolName,
   displayTitle,
+  activityDescription,
   status,
 }: ToolCallItemProps) {
   const Icon =
@@ -21,7 +22,7 @@ export function HeroToolCallItem({
         : getToolIcon(toolName)
   const activity = (
     <ActivityStatus
-      label={getToolStatusDisplayTitle(displayTitle, status, toolName)}
+      label={getToolStatusDisplayTitle(displayTitle, status, toolName, activityDescription)}
       isActive={status === 'executing'}
       icon={<Icon className='size-full' />}
     />
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group-view.tsx b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group-view.tsx
index c9733459807..32183aec931 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group-view.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group-view.tsx
@@ -4,6 +4,7 @@ import { type ComponentType, type ReactNode, useMemo, useState } from 'react'
 import { ActivityStatus } from '@/components/ui/activity-status'
 import { isBrowserAgentAvailable } from '@/lib/browser-agent/transport'
 import { RETIRED_BROWSER_REQUEST_TAKEOVER_ID } from '@/lib/copilot/tools/retired-tools'
+import { getToolStatusDisplayTitle } from '@/lib/copilot/tools/tool-display'
 import { ActivityDisclosure } from '@/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/activity-disclosure'
 import { BrowserAgentIcon } from '@/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/browser-agent-icon'
 import { renderInlineMarkdown } from '@/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/inline-markdown'
@@ -52,7 +53,12 @@ export interface AgentGroupProps {
 }
 
 function toolStatusTitle(tool: ToolCallData): string {
-  return tool.displayTitle || String(tool.toolName ?? '')
+  return getToolStatusDisplayTitle(
+    tool.displayTitle || String(tool.toolName ?? ''),
+    tool.status,
+    tool.toolName,
+    tool.activityDescription
+  )
 }
 
 /**
@@ -213,6 +219,7 @@ export function AgentGroupView({
           toolCallId={item.data.id}
           toolName={item.data.toolName}
           displayTitle={item.data.displayTitle}
+          activityDescription={item.data.activityDescription}
           status={item.data.status}
           params={item.data.params}
           result={item.data.result}
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group.test.ts b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group.test.ts
index 8dd4c725517..1e0b1923cdc 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group.test.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/agent-group.test.ts
@@ -120,6 +120,43 @@ describe('AgentGroup inline main activity', () => {
     container.remove()
   })
 
+  it.each(['mothership', 'workflow', 'browser'])(
+    'uses the same model description in the %s live header and expanded row',
+    (agentName) => {
+      act(() =>
+        root.render(
+          createElement(AgentGroup, {
+            agentName,
+            agentLabel: agentName,
+            defaultExpanded: true,
+            isLaneOpen: true,
+            isStreaming: true,
+            items: [
+              {
+                type: 'tool',
+                data: {
+                  id: 'described-read',
+                  toolName: 'read',
+                  displayTitle: 'Reading files',
+                  activityDescription: 'Checking the project timeline',
+                  status: 'executing',
+                },
+              },
+            ],
+          })
+        )
+      )
+
+      const statuses = [...container.querySelectorAll('[role="status"]')]
+      expect(statuses).toHaveLength(agentName === 'mothership' ? 1 : 2)
+      for (const status of statuses) {
+        expect(status.textContent).toContain('Checking the project timeline')
+      }
+      expect(container.textContent).not.toContain('Reading files')
+      expect(container.querySelector('[class*="shimmer"]')).not.toBeNull()
+    }
+  )
+
   it.each([
     ['executing', 'Reading notes'],
     ['success', 'Read notes'],
@@ -733,6 +770,6 @@ describe('AgentGroup nested status line', () => {
       namedTool('Reading workflow', 'success' as ToolCallStatus, 1),
       group([namedTool('Deploying Invoice Sync as API', 'success' as ToolCallStatus, 2)]),
     ])
-    expect(header).toContain('Workflow Agent — Deploying Invoice Sync as API')
+    expect(header).toContain('Workflow Agent — Deployed Invoice Sync as API')
   })
 })
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-activity-group.tsx b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-activity-group.tsx
index d426fe587da..d86c2fbd3af 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-activity-group.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-activity-group.tsx
@@ -15,7 +15,12 @@ const MAX_SUMMARY_ACTIONS = 2
 export function getToolActivitySummary(tools: ToolCallData[]): string {
   if (tools.length === 1) {
     const tool = tools[0]
-    return getToolStatusDisplayTitle(tool.displayTitle, tool.status, tool.toolName)
+    return getToolStatusDisplayTitle(
+      tool.displayTitle,
+      tool.status,
+      tool.toolName,
+      tool.activityDescription
+    )
   }
   const labels = new Set<string>()
   let failed = 0
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx
index b52d7b1b0e6..a67ea10d4de 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx
@@ -48,6 +48,89 @@ describe('ToolCallItem', () => {
     expect(markup).not.toContain('Writing brief.md')
   })
 
+  it.each([
+    ['executing', 'Checking the invoice totals'],
+    ['success', 'Checked the invoice totals'],
+    ['error', 'Failed checking the invoice totals'],
+    ['cancelled', 'Stopped checking the invoice totals'],
+    ['rejected', 'Failed checking the invoice totals'],
+    ['skipped', 'Skipped checking the invoice totals'],
+  ] as const)(
+    'projects %s from the actual tool status onto the model description',
+    (status, title) => {
+      const markup = renderToStaticMarkup(
+        <ToolCallItem
+          toolName='prepare_file_edit'
+          displayTitle='Editing report.md'
+          activityDescription='Checking the invoice totals'
+          status={status}
+          streamingArgs='{"operation":"patch","title":"report.md"}'
+        />
+      )
+
+      expect(markup).toContain(title)
+      expect(markup).not.toContain('report.md')
+    }
+  )
+
+  it.each(['   ', 'a'.repeat(161)])(
+    'uses the existing title for an invalid description',
+    (activityDescription) => {
+      const markup = renderToStaticMarkup(
+        <ToolCallItem
+          toolName='grep'
+          displayTitle='Searching files'
+          activityDescription={activityDescription}
+          status='executing'
+        />
+      )
+
+      expect(markup).toContain('Searching files')
+    }
+  )
+
+  it('keeps an executing wait countdown in place of the model phrase', () => {
+    const markup = renderToStaticMarkup(
+      <ToolCallItem
+        toolName='wait'
+        displayTitle='Waiting'
+        activityDescription='Waiting for the export'
+        status='executing'
+        params={{ seconds: 10 }}
+      />
+    )
+
+    expect(markup).toContain('10s')
+    expect(markup).not.toContain('Waiting for the export')
+  })
+
+  it('renders model descriptions as text, without interpreting markup', () => {
+    const markup = renderToStaticMarkup(
+      <ToolCallItem
+        toolName='read'
+        displayTitle='Reading a page'
+        activityDescription='Reading <script>alert(1)</script>'
+        status='executing'
+      />
+    )
+
+    expect(markup).toContain('&lt;script&gt;')
+    expect(markup).not.toContain('<script>')
+  })
+
+  it('does not let model-authored outcome wording override a failure', () => {
+    const markup = renderToStaticMarkup(
+      <ToolCallItem
+        toolName='read'
+        displayTitle='Reading a page'
+        activityDescription='Stopped checking invoices'
+        status='error'
+      />
+    )
+
+    expect(markup).toContain('Failed: Stopped checking invoices')
+  })
+
   it('defensively applies the completed verb for every successful tool row', () => {
     const markup = renderToStaticMarkup(
       <ToolCallItem toolName='diff_workflows' displayTitle='Comparing workflows' status='success' />
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.tsx b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.tsx
index f7a1c4ceaae..116d6723ddb 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.tsx
@@ -45,6 +45,7 @@ export function CircleStop({ className }: { className?: string }) {
 export interface ToolCallItemProps {
   toolName: string
   displayTitle: string
+  activityDescription?: string
   status: ToolCallStatus
   params?: Record<string, unknown>
   result?: ToolCallData['result']
@@ -125,6 +126,7 @@ function useElapsedMs(
 export function ToolCallItem({
   toolName,
   displayTitle,
+  activityDescription,
   status,
   params,
   result,
@@ -188,7 +190,12 @@ export function ToolCallItem({
   const liveTitle = isCountingDown
     ? getWaitCountdownTitle(params, elapsedMs)
     : liveWorkspaceFileTitle || displayTitle
-  const title = getToolStatusDisplayTitle(liveTitle, status, toolName)
+  const title = getToolStatusDisplayTitle(
+    liveTitle,
+    status,
+    toolName,
+    isCountingDown ? undefined : activityDescription
+  )
 
   // A waiting terminal handoff swaps its row for the hand-back chip, the same
   // way a browser takeover does: the row would otherwise spin with nothing
@@ -209,7 +216,7 @@ export function ToolCallItem({
       <ToolPermissionCard
         toolCallId={toolCallId}
         toolName={toolName}
-        displayTitle={liveTitle}
+        displayTitle={title}
         params={params}
       />
     )
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.test.ts b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.test.ts
index c89261507ee..ab66c806c66 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.test.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.test.ts
@@ -162,6 +162,33 @@ describe('getOrchestratorMessageText', () => {
 })
 
 describe('parseBlocks span-identity tree', () => {
+  it.each(['read', 'respond', 'prepare_file_edit'])(
+    'prefers invocation intent over %s fallback titles',
+    (name) => {
+      const segments = parseBlocks([
+        {
+          type: 'tool_call',
+          toolCall: {
+            id: 'described-tool',
+            name,
+            status: 'success',
+            displayTitle: 'Fallback title',
+            activityDescription: '  Checking\nlaunch updates ',
+            params: { path: 'workspace/files/brief.md' },
+          },
+          timestamp: 1,
+        },
+      ])
+      const group = segments[0]
+      if (group.type !== 'agent_group') throw new Error('expected mothership group')
+      const tool = group.items[0]
+      if (tool?.type !== 'tool') throw new Error('expected tool activity')
+      expect(tool.data.displayTitle).toBe('Checked launch updates')
+      expect(tool.data.activityDescription).toBe('Checking launch updates')
+      expect(tool.data.params).toEqual({ path: 'workspace/files/brief.md' })
+    }
+  )
+
   it('refines a completed credential rename with its previous and new names', () => {
     const segments = parseBlocks([
       {
diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.tsx b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.tsx
index 54931cf07dd..2f029348744 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.tsx
@@ -19,6 +19,7 @@ import {
   getToolDisplayTitle,
   getToolStatusDisplayTitle,
   humanizeToolName,
+  normalizeToolActivityDescription,
 } from '@/lib/copilot/tools/tool-display'
 import { useChatSurface } from '@/app/workspace/[workspaceId]/home/components/chat-surface-context'
 import type { CredentialSubmissionPayload } from '@/app/workspace/[workspaceId]/home/components/message-content/components/special-tags'
@@ -200,15 +201,22 @@ function getOverrideDisplayTitle(tc: NonNullable<ContentBlock['toolCall']>): str
 }
 
 function toToolData(tc: NonNullable<ContentBlock['toolCall']>): ToolCallData {
+  const activityDescription = normalizeToolActivityDescription(tc.activityDescription)
   const overrideDisplayTitle = getOverrideDisplayTitle(tc)
   const resolvedTitle =
     overrideDisplayTitle || tc.displayTitle || getToolDisplayTitle(tc.name, tc.params)
-  const displayTitle = getToolStatusDisplayTitle(resolvedTitle, tc.status, tc.name)
+  const displayTitle = getToolStatusDisplayTitle(
+    resolvedTitle,
+    tc.status,
+    tc.name,
+    activityDescription
+  )
 
   return {
     id: tc.id,
     toolName: tc.name,
     displayTitle,
+    activityDescription,
     status: tc.status,
     params: tc.params,
     result: tc.result,
diff --git a/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.test.ts b/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.test.ts
index a764b32fa9b..242f236c5ba 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.test.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.test.ts
@@ -112,6 +112,107 @@ function blocksByType(blocks: ReturnType<typeof modelToContentBlocks>, type: str
   return blocks.filter((b) => b.type === type)
 }
 
+describe('model-authored tool activities', () => {
+  it.each(['main', 'subagent'] as const)(
+    'keeps %s descriptions stable through completion and snapshot replay',
+    (lane) => {
+      const scope: Scope | undefined =
+        lane === 'subagent'
+          ? { lane, spanId: 'browser-span', parentSpanId: 'main', agentId: 'browser' }
+          : undefined
+      const m = build([
+        env(
+          1,
+          'tool',
+          {
+            phase: 'call',
+            toolCallId: 'activity-call',
+            toolName: 'browser_click',
+            partial: true,
+          },
+          scope
+        ),
+      ])
+      expect(
+        modelToContentBlocks(m).find((b) => b.toolCall)?.toolCall?.activityDescription
+      ).toBeUndefined()
+      reduceEvent(
+        m,
+        env(
+          2,
+          'tool',
+          {
+            phase: 'call',
+            toolCallId: 'activity-call',
+            toolName: 'browser_click',
+            arguments: { ref: 'button-1' },
+            activityDescription: '  Opening  the export menu ',
+          },
+          scope
+        )
+      )
+      reduceEvent(
+        m,
+        env(
+          3,
+          'tool',
+          {
+            phase: 'result',
+            toolCallId: 'activity-call',
+            toolName: 'browser_click',
+            success: true,
+          },
+          scope
+        )
+      )
+      reduceEvent(
+        m,
+        env(
+          4,
+          'tool',
+          {
+            phase: 'call',
+            toolCallId: 'activity-call',
+            toolName: 'browser_click',
+            arguments: { ref: 'button-1' },
+            activityDescription: 'Opening another menu',
+          },
+          scope
+        )
+      )
+      const blocks = modelToContentBlocks(m)
+      const expected = {
+        status: 'success',
+        activityDescription: 'Opening the export menu',
+        displayTitle: 'Opening the export menu',
+        params: { ref: 'button-1' },
+      }
+      expect(blocks.find((b) => b.toolCall)?.toolCall).toMatchObject(expected)
+      const replayed = modelToContentBlocks(contentBlocksToModel(blocks))
+      expect(replayed.find((b) => b.toolCall)?.toolCall).toMatchObject(expected)
+    }
+  )
+
+  it.each([undefined, '', '   ', 12, 'x'.repeat(161)])(
+    'falls back to deterministic wording for invalid metadata %s',
+    (activityDescription) => {
+      const blocks = modelToContentBlocks(
+        build([
+          env(1, 'tool', {
+            phase: 'call',
+            toolCallId: 'fallback-call',
+            toolName: 'run_function',
+            arguments: { title: 'Checking the project setup' },
+            activityDescription,
+          }),
+        ])
+      )
+      expect(blocks[0].toolCall).toMatchObject({ displayTitle: 'Checking the project setup' })
+      expect(blocks[0].toolCall?.activityDescription).toBeUndefined()
+    }
+  )
+})
+
 describe('modelToContentBlocks', () => {
   it('emits main-lane blocks without spanId and subagent-lane blocks with spanId', () => {
     const blocks = modelToContentBlocks(build(fileDelegationEvents()))
diff --git a/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.ts b/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.ts
index 6088ee0419a..4cc1f5e7233 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model-serialize.ts
@@ -44,12 +44,13 @@ function isOpenToolStatus(status: ToolCallStatus): boolean {
 
 /**
  * Resolves a tool row's display title with the same precedence the live handler
- * used: the integration gateway's model-authored activity description first
- * (live even mid-argument-stream; the integration brand is the row icon), then
+ * used: the per-call model-authored activity description, then the legacy
+ * integration gateway description (live even mid-argument-stream), then
  * the streaming-args title while args stream, then the arg-derived title, then
  * the explicit `ui.title`.
  */
 function toolDisplayTitle(node: ToolNode): string | undefined {
+  if (node.activityDescription) return node.activityDescription
   const integrationTitle = resolveIntegrationToolDisplayTitle(node)
   if (integrationTitle) return integrationTitle
   const streamingTitle = node.streamingArgs
@@ -136,6 +137,7 @@ export function modelToContentBlocks(model: TurnModel): ContentBlock[] {
             name: node.name,
             status: nodeToToolStatus(node.status),
             ...(displayTitle ? { displayTitle } : {}),
+            ...(node.activityDescription ? { activityDescription: node.activityDescription } : {}),
             ...(node.integrationDescription
               ? { integrationDescription: node.integrationDescription }
               : {}),
@@ -308,6 +310,7 @@ export function contentBlocksToModel(blocks: ContentBlock[]): TurnModel {
             toolCallId: tc.id,
             toolName: tc.name,
             arguments: tc.params,
+            ...(tc.activityDescription ? { activityDescription: tc.activityDescription } : {}),
             // Carries an unanswered permission prompt across a snapshot rebuild
             // so the reloaded row is still actionable rather than a spinner.
             ...(tc.status === ToolCallStatus.awaiting_approval
diff --git a/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model.ts b/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model.ts
index 6097a22cf76..0b3bf5992d5 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/hooks/stream/turn-model.ts
@@ -11,7 +11,10 @@ import {
 import { CallIntegrationTool } from '@/lib/copilot/generated/tool-catalog-v1'
 import type { PersistedStreamEventEnvelope } from '@/lib/copilot/request/session/contract'
 import { extractStreamingStringArgument } from '@/lib/copilot/tools/streaming-args'
-import { CONTEXT_COMPACTION_DISPLAY_TITLE } from '@/lib/copilot/tools/tool-display'
+import {
+  CONTEXT_COMPACTION_DISPLAY_TITLE,
+  normalizeToolActivityDescription,
+} from '@/lib/copilot/tools/tool-display'
 
 /**
  * The single deterministic model of one assistant turn, derived purely from the
@@ -65,6 +68,8 @@ export interface ToolNode extends NodeBase {
   args?: Record<string, unknown>
   streamingArgs?: string
   uiTitle?: string
+  /** Model-authored activity text preserved across stream and snapshot replay. */
+  activityDescription?: string
   /**
    * Model-authored activity phrase for a gateway-resolved integration call
    * (e.g. "Reading recent emails"). Captured when the authoritative resolved
@@ -513,6 +518,7 @@ export function reduceEvent(model: TurnModel, envelope: PersistedStreamEventEnve
           tsMs
         )
         rebindResolvedIntegrationCall(node, toolName)
+        node.activityDescription ??= normalizeToolActivityDescription(payload.activityDescription)
         // Sim stamps this onto the call frame for a tool it is holding behind a
         // permission prompt. Only ever moves a live node INTO the waiting state;
         // a node that already has a result stays terminal, so a replayed call
@@ -531,8 +537,6 @@ export function reduceEvent(model: TurnModel, envelope: PersistedStreamEventEnve
         // description across a preserve-state rebuild.
         const restoredDescription = asString(payload.integrationDescription)
         if (restoredDescription) node.integrationDescription = restoredDescription
-        // Tool-call titles are derived from the tool name (+args) at serialize
-        // time; the stream only carries behavioral flags now.
         const ui = isRecordLike(payload.ui) ? payload.ui : undefined
         if (ui?.hidden === true) node.hidden = true
       } else if (phase === MothershipStreamV1ToolPhase.args_delta) {
diff --git a/apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.ts b/apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.ts
index 549a636aefa..c2ede00f541 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.ts
@@ -827,6 +827,9 @@ function toRawPersistedContentBlockBody(block: ContentBlock): Record<string, unk
           id: block.toolCall.id,
           name: block.toolCall.name,
           state: block.toolCall.status,
+          ...(block.toolCall.activityDescription
+            ? { activityDescription: block.toolCall.activityDescription }
+            : {}),
           ...(block.toolCall.params ? { params: block.toolCall.params } : {}),
           ...(block.toolCall.result ? { result: block.toolCall.result } : {}),
           ...(block.toolCall.calledBy ? { calledBy: block.toolCall.calledBy } : {}),
@@ -3601,6 +3604,9 @@ export function useChat(
               name: block.toolCall.name,
               state: isCancelled ? MothershipStreamV1ToolOutcome.cancelled : block.toolCall.status,
               params: block.toolCall.params,
+              ...(block.toolCall.activityDescription
+                ? { activityDescription: block.toolCall.activityDescription }
+                : {}),
               result: block.toolCall.result,
               ...(display ? { display } : {}),
               calledBy: block.toolCall.calledBy,
diff --git a/apps/sim/app/workspace/[workspaceId]/home/types.ts b/apps/sim/app/workspace/[workspaceId]/home/types.ts
index 15e8d9a1e1c..3844d7beea9 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/types.ts
+++ b/apps/sim/app/workspace/[workspaceId]/home/types.ts
@@ -73,6 +73,7 @@ export interface ToolCallData {
   id: string
   toolName: string
   displayTitle: string
+  activityDescription?: string
   status: ToolCallStatus
   params?: Record<string, unknown>
   result?: ToolCallResult
@@ -86,6 +87,8 @@ export interface ToolCallInfo {
   name: string
   status: ToolCallStatus
   displayTitle?: string
+  /** Model-authored activity text, separate from executable tool arguments. */
+  activityDescription?: string
   /** Model-authored activity phrase for a gateway-resolved integration call. */
   integrationDescription?: string
   params?: Record<string, unknown>
diff --git a/apps/sim/lib/api/contracts/copilot.ts b/apps/sim/lib/api/contracts/copilot.ts
index 7764656c753..5b57bfb830b 100644
--- a/apps/sim/lib/api/contracts/copilot.ts
+++ b/apps/sim/lib/api/contracts/copilot.ts
@@ -203,6 +203,7 @@ const storedToolCallSchema = z
     id: z.string().optional(),
     name: z.string().optional(),
     state: z.string().optional(),
+    activityDescription: z.string().optional(),
     params: z.record(z.string(), z.unknown()).optional(),
     result: z
       .object({
diff --git a/apps/sim/lib/copilot/chat/display-message.ts b/apps/sim/lib/copilot/chat/display-message.ts
index cce57fe0b7b..d185f2b27a1 100644
--- a/apps/sim/lib/copilot/chat/display-message.ts
+++ b/apps/sim/lib/copilot/chat/display-message.ts
@@ -5,6 +5,7 @@ import {
   MothershipStreamV1ToolOutcome,
 } from '@/lib/copilot/generated/mothership-stream-v1'
 import { isToolHiddenInUi } from '@/lib/copilot/tools/client/hidden-tools'
+import { normalizeToolActivityDescription } from '@/lib/copilot/tools/tool-display'
 import {
   type ChatContextKind,
   type ChatMessage,
@@ -38,11 +39,13 @@ function toToolCallInfo(block: PersistedContentBlock): ToolCallInfo | undefined
   if (!tc) return undefined
   if (isToolHiddenInUi(tc.name)) return undefined
   const status: ToolCallStatus = STATE_TO_STATUS[tc.state] ?? ToolCallStatus.error
+  const activityDescription = normalizeToolActivityDescription(tc.activityDescription)
   return {
     id: tc.id,
     name: tc.name,
     status,
     displayTitle: status === ToolCallStatus.cancelled ? 'Stopped by user' : tc.display?.title,
+    ...(activityDescription ? { activityDescription } : {}),
     params: tc.params,
     calledBy: tc.calledBy,
     result: tc.result,
diff --git a/apps/sim/lib/copilot/chat/effective-transcript.test.ts b/apps/sim/lib/copilot/chat/effective-transcript.test.ts
index c525a2cc81d..92672da3382 100644
--- a/apps/sim/lib/copilot/chat/effective-transcript.test.ts
+++ b/apps/sim/lib/copilot/chat/effective-transcript.test.ts
@@ -39,6 +39,70 @@ function buildUserMessage(id: string, content: string) {
 }
 
 describe('buildEffectiveChatTranscript', () => {
+  it.each(['main', 'subagent'] as const)(
+    'retains each %s activity description when reconstructing live history',
+    (lane) => {
+      const scope =
+        lane === 'subagent'
+          ? {
+              lane,
+              spanId: 'browser-span',
+              parentSpanId: 'main',
+              parentToolCallId: 'browser-parent',
+              agentId: 'browser',
+            }
+          : undefined
+      const call = (seq: number, toolCallId: string, activityDescription?: string) =>
+        toBatchEvent(seq, {
+          v: 1,
+          seq,
+          ts: new Date(seq).toISOString(),
+          type: MothershipStreamV1EventType.tool,
+          stream: { streamId: 'stream-1' },
+          scope,
+          payload: {
+            phase: 'call',
+            executor: 'go',
+            mode: 'sync',
+            toolCallId,
+            toolName: 'browser_click',
+            arguments: { ref: toolCallId },
+            activityDescription,
+          },
+        })
+      const result = buildEffectiveChatTranscript({
+        messages: [buildUserMessage('stream-1', 'Open the project settings')],
+        activeStreamId: 'stream-1',
+        streamSnapshot: {
+          events: [
+            call(1, 'menu-call', 'Opening the project menu'),
+            call(2, 'settings-call', 'Opening the settings page'),
+            call(3, 'menu-call'),
+          ],
+          previewSessions: [],
+          status: 'active',
+        },
+      })
+      const tools = result[1].contentBlocks
+        ?.filter((block) => block.toolCall)
+        .map((block) => block.toolCall)
+      expect(tools).toEqual([
+        expect.objectContaining({
+          id: 'menu-call',
+          activityDescription: 'Opening the project menu',
+          display: { title: 'Opening the project menu' },
+          params: { ref: 'menu-call' },
+        }),
+        expect.objectContaining({
+          id: 'settings-call',
+          activityDescription: 'Opening the settings page',
+          display: { title: 'Opening the settings page' },
+          params: { ref: 'settings-call' },
+        }),
+      ])
+    }
+  )
+
   it('returns the existing transcript when the stream owner is no longer the trailing user', () => {
     const messages = [
       buildUserMessage('stream-1', 'Hello'),
diff --git a/apps/sim/lib/copilot/chat/effective-transcript.ts b/apps/sim/lib/copilot/chat/effective-transcript.ts
index fd1e4423590..882ef7557a2 100644
--- a/apps/sim/lib/copilot/chat/effective-transcript.ts
+++ b/apps/sim/lib/copilot/chat/effective-transcript.ts
@@ -18,6 +18,7 @@ import type { StreamBatchEvent } from '@/lib/copilot/request/session/types'
 import {
   CONTEXT_COMPACTION_DISPLAY_TITLE,
   getToolDisplayTitle,
+  normalizeToolActivityDescription,
 } from '@/lib/copilot/tools/tool-display'
 
 interface StreamSnapshotLike {
@@ -187,6 +188,7 @@ function buildLiveAssistantMessage(params: {
     spanId?: string
     parentSpanId?: string
     displayTitle?: string
+    activityDescription?: string
     params?: Record<string, unknown>
     result?: { success: boolean; output?: unknown; error?: string }
     state?: string
@@ -199,6 +201,10 @@ function buildLiveAssistantMessage(params: {
     if (existingIndex !== undefined) {
       const existing = blocks[existingIndex]
       const existingToolCall = asPayloadRecord(existing.toolCall)
+      const activityDescription =
+        normalizeToolActivityDescription(existingToolCall?.activityDescription) ??
+        input.activityDescription
+      const displayTitle = activityDescription ?? input.displayTitle
       existing.toolCall = {
         ...(existingToolCall ?? {}),
         id: input.toolCallId,
@@ -209,10 +215,11 @@ function buildLiveAssistantMessage(params: {
         ...(ownershipWritable && input.calledBy ? { calledBy: input.calledBy } : {}),
         ...(input.params ? { params: input.params } : {}),
         ...(input.result ? { result: input.result } : {}),
-        ...(input.displayTitle
+        ...(activityDescription ? { activityDescription } : {}),
+        ...(displayTitle
           ? {
               display: {
-                title: input.displayTitle,
+                title: displayTitle,
               },
             }
           : existingToolCall?.display
@@ -247,6 +254,7 @@ function buildLiveAssistantMessage(params: {
         ...(input.calledBy ? { calledBy: input.calledBy } : {}),
         ...(input.params ? { params: input.params } : {}),
         ...(input.result ? { result: input.result } : {}),
+        ...(input.activityDescription ? { activityDescription: input.activityDescription } : {}),
         ...(input.displayTitle
           ? {
               display: {
@@ -366,16 +374,20 @@ function buildLiveAssistantMessage(params: {
           continue
         }
 
+        const activityDescription = normalizeToolActivityDescription(payload.activityDescription)
         ensureToolBlock({
           toolCallId,
           toolName: payload.toolName,
+          activityDescription,
           calledBy: scopedSubagent,
           ...(parentForBlock ? { parentToolCallId: parentForBlock } : {}),
           ...spanIdentity,
-          displayTitle: getToolDisplayTitle(
-            payload.toolName,
-            isRecordLike(payload.arguments) ? payload.arguments : undefined
-          ),
+          displayTitle:
+            activityDescription ??
+            getToolDisplayTitle(
+              payload.toolName,
+              isRecordLike(payload.arguments) ? payload.arguments : undefined
+            ),
           params: isRecordLike(payload.arguments) ? payload.arguments : undefined,
           state: typeof payload.status === 'string' ? payload.status : 'executing',
           isCallFrame: payload.phase === MothershipStreamV1ToolPhase.call,
diff --git a/apps/sim/lib/copilot/chat/persisted-message.test.ts b/apps/sim/lib/copilot/chat/persisted-message.test.ts
index 71a3f292156..015be248d1b 100644
--- a/apps/sim/lib/copilot/chat/persisted-message.test.ts
+++ b/apps/sim/lib/copilot/chat/persisted-message.test.ts
@@ -3,6 +3,7 @@
  */
 
 import { describe, expect, it } from 'vitest'
+import { copilotChatStopBodySchema } from '@/lib/api/contracts/copilot'
 import { toDisplayMessage } from '@/lib/copilot/chat/display-message'
 import type { OrchestratorResult } from '@/lib/copilot/request/types'
 import { resolveMessageCitations } from '@/app/workspace/[workspaceId]/home/components/message-content/resolve-citations'
@@ -15,6 +16,86 @@ import {
 } from './persisted-message'
 
 describe('persisted-message', () => {
+  it.each(['success', 'cancelled'] as const)(
+    'preserves model-authored activity metadata through persisted %s history and stop validation',
+    (status) => {
+      const result: OrchestratorResult = {
+        success: true,
+        content: '',
+        toolCalls: [],
+        contentBlocks: [
+          {
+            type: 'tool_call',
+            timestamp: 1,
+            toolCall: {
+              id: 'activity-call',
+              name: 'read',
+              status,
+              activityDescription: '  Checking   the project setup  ',
+              displayTitle: 'Checking the project setup',
+              params: { path: 'WORKSPACE.md' },
+            },
+          },
+        ],
+      }
+      const persisted = buildPersistedAssistantMessage(result)
+      const stopped = copilotChatStopBodySchema.parse({
+        chatId: 'chat-1',
+        streamId: 'stream-1',
+        content: '',
+        contentBlocks: persisted.contentBlocks,
+      })
+      expect(stopped.contentBlocks?.[0].toolCall?.activityDescription).toBe(
+        'Checking the project setup'
+      )
+      const display = toDisplayMessage(
+        normalizeMessage(persisted as unknown as Record<string, unknown>)
+      )
+      expect(display.contentBlocks?.[0].toolCall).toMatchObject({
+        status,
+        activityDescription: 'Checking the project setup',
+        params: { path: 'WORKSPACE.md' },
+      })
+    }
+  )
+
+  it('preserves activity metadata on legacy tool blocks without inferring it from old titles', () => {
+    const message = normalizeMessage({
+      id: 'message-1',
+      role: 'assistant',
+      content: '',
+      contentBlocks: [
+        {
+          type: 'tool_call',
+          toolCall: {
+            id: 'activity-call',
+            name: 'read',
+            state: 'success',
+            activityDescription: 'Checking the project setup',
+            display: { title: 'Checking the project setup' },
+          },
+        },
+        {
+          type: 'tool_call',
+          toolCall: {
+            id: 'legacy-call',
+            name: 'gmail_read_v2',
+            state: 'success',
+            display: { title: 'Read recent emails' },
+          },
+        },
+      ],
+    })
+    const display = toDisplayMessage(message)
+    expect(display.contentBlocks?.[0].toolCall?.activityDescription).toBe(
+      'Checking the project setup'
+    )
+    expect(display.contentBlocks?.[1].toolCall).toMatchObject({
+      displayTitle: 'Read recent emails',
+    })
+    expect(display.contentBlocks?.[1].toolCall?.activityDescription).toBeUndefined()
+  })
+
   it('round-trips canonical tool blocks through normalizeMessage', () => {
     const blockTimestamp = 1_700_000_000_000
     const result: OrchestratorResult = {
diff --git a/apps/sim/lib/copilot/chat/persisted-message.ts b/apps/sim/lib/copilot/chat/persisted-message.ts
index 85db3536dc6..8a01e6ab60c 100644
--- a/apps/sim/lib/copilot/chat/persisted-message.ts
+++ b/apps/sim/lib/copilot/chat/persisted-message.ts
@@ -22,6 +22,7 @@ import type {
   OrchestratorResult,
 } from '@/lib/copilot/request/types'
 import { RETIRED_BROWSER_REQUEST_TAKEOVER_ID } from '@/lib/copilot/tools/retired-tools'
+import { normalizeToolActivityDescription } from '@/lib/copilot/tools/tool-display'
 import type { BrowserTextSelection, TerminalTextSelection } from '@/stores/panel/types'
 
 export type PersistedToolState = LocalToolCallStatus | MothershipStreamV1ToolOutcome | 'interrupted'
@@ -36,6 +37,7 @@ interface PersistedToolCall {
   calledBy?: string
   durationMs?: number
   display?: { title?: string }
+  activityDescription?: string
 }
 
 export interface PersistedContentBlock {
@@ -284,10 +286,14 @@ function mapContentBlockBody(block: ContentBlock): PersistedContentBlock {
 
       const redactedResult = redactToolCallResult(block.toolCall.name, block.toolCall.result)
 
+      const activityDescription = normalizeToolActivityDescription(
+        block.toolCall.activityDescription
+      )
       const toolCall: PersistedToolCall = {
         id: block.toolCall.id,
         name: block.toolCall.name,
         state,
+        ...(activityDescription ? { activityDescription } : {}),
         ...(isSubagentTool && isNonTerminal ? {} : { result: redactedResult }),
         ...(isSubagentTool && isNonTerminal
           ? {}
@@ -466,6 +472,7 @@ interface RawBlock {
     params?: Record<string, unknown>
     result?: { success: boolean; output?: unknown; error?: string }
     display?: { text?: string; title?: string; phaseLabel?: string }
+    activityDescription?: string
     calledBy?: string
     durationMs?: number
     error?: string
@@ -523,10 +530,12 @@ function normalizeCanonicalBlock(block: RawBlock): PersistedContentBlock {
   if (block.status) result.status = block.status as MothershipStreamV1CompletionStatus
   if (block.parentToolCallId) result.parentToolCallId = block.parentToolCallId
   if (block.toolCall) {
+    const activityDescription = normalizeToolActivityDescription(block.toolCall.activityDescription)
     result.toolCall = {
       id: block.toolCall.id ?? '',
       name: block.toolCall.name ?? '',
       state: normalizeToolState(block.toolCall.state),
+      ...(activityDescription ? { activityDescription } : {}),
       ...(block.toolCall.params ? { params: block.toolCall.params } : {}),
       ...(block.toolCall.result ? { result: block.toolCall.result } : {}),
       ...(block.toolCall.calledBy ? { calledBy: block.toolCall.calledBy } : {}),
@@ -549,6 +558,7 @@ function normalizeCanonicalBlock(block: RawBlock): PersistedContentBlock {
 
 function normalizeLegacyBlock(block: RawBlock): PersistedContentBlock {
   if (block.type === 'tool_call' && block.toolCall) {
+    const activityDescription = normalizeToolActivityDescription(block.toolCall.activityDescription)
     return {
       type: MothershipStreamV1EventType.tool,
       phase: MothershipStreamV1ToolPhase.call,
@@ -556,6 +566,7 @@ function normalizeLegacyBlock(block: RawBlock): PersistedContentBlock {
         id: block.toolCall.id ?? '',
         name: block.toolCall.name ?? '',
         state: normalizeToolState(block.toolCall.state),
+        ...(activityDescription ? { activityDescription } : {}),
         ...(block.toolCall.params ? { params: block.toolCall.params } : {}),
         ...(block.toolCall.result ? { result: block.toolCall.result } : {}),
         ...(block.toolCall.calledBy ? { calledBy: block.toolCall.calledBy } : {}),
diff --git a/apps/sim/lib/copilot/generated/mothership-stream-v1-schema.ts b/apps/sim/lib/copilot/generated/mothership-stream-v1-schema.ts
index ecf8faf3f82..89cafd97fae 100644
--- a/apps/sim/lib/copilot/generated/mothership-stream-v1-schema.ts
+++ b/apps/sim/lib/copilot/generated/mothership-stream-v1-schema.ts
@@ -1176,6 +1176,10 @@ export const MOTHERSHIP_STREAM_V1_SCHEMA: JsonSchema = {
     MothershipStreamV1ToolCallDescriptor: {
       additionalProperties: false,
       properties: {
+        activityDescription: {
+          maxLength: 160,
+          type: 'string',
+        },
         arguments: {
           $ref: '#/$defs/MothershipStreamV1AdditionalPropertiesMap',
         },
diff --git a/apps/sim/lib/copilot/generated/mothership-stream-v1.ts b/apps/sim/lib/copilot/generated/mothership-stream-v1.ts
index 41a169a8648..421cab83293 100644
--- a/apps/sim/lib/copilot/generated/mothership-stream-v1.ts
+++ b/apps/sim/lib/copilot/generated/mothership-stream-v1.ts
@@ -144,6 +144,7 @@ export interface MothershipStreamV1ToolCallEventEnvelope {
   v: 1
 }
 export interface MothershipStreamV1ToolCallDescriptor {
+  activityDescription?: string
   arguments?: MothershipStreamV1AdditionalPropertiesMap
   executor: MothershipStreamV1ToolExecutor
   mode: MothershipStreamV1ToolMode
diff --git a/apps/sim/lib/copilot/request/handlers/handlers.test.ts b/apps/sim/lib/copilot/request/handlers/handlers.test.ts
index 33b1e718d59..cb1d2f9ea99 100644
--- a/apps/sim/lib/copilot/request/handlers/handlers.test.ts
+++ b/apps/sim/lib/copilot/request/handlers/handlers.test.ts
@@ -1870,6 +1870,7 @@ describe('sse-handlers tool lifecycle', () => {
           toolCallId: 'tool-dynamic-sim',
           toolName: 'gmail_read',
           arguments: { maxResults: 10 },
+          activityDescription: 'Reading the latest project updates',
           executor: MothershipStreamV1ToolExecutor.sim,
           mode: MothershipStreamV1ToolMode.async,
           phase: MothershipStreamV1ToolPhase.call,
@@ -1886,8 +1887,92 @@ describe('sse-handlers tool lifecycle', () => {
     expect(context.toolCalls.get('tool-dynamic-sim')?.status).toBe(
       MothershipStreamV1ToolOutcome.success
     )
+    expect(context.toolCalls.get('tool-dynamic-sim')?.activityDescription).toBe(
+      'Reading the latest project updates'
+    )
   })
 
+  it.each(['main', 'subagent'] as const)(
+    'retains a model-authored description on a finalized %s call without changing arguments',
+    async (lane) => {
+      isSimExecuted.mockReturnValue(false)
+      const handler = lane === 'subagent' ? subAgentHandlers.tool : sseHandlers.tool
+      const scope =
+        lane === 'subagent'
+          ? { lane, parentToolCallId: 'activity-parent', agentId: 'workflow' }
+          : undefined
+      const payload = {
+        toolCallId: `activity-${lane}`,
+        toolName: 'run_function',
+        executor: MothershipStreamV1ToolExecutor.go,
+        mode: MothershipStreamV1ToolMode.sync,
+        phase: MothershipStreamV1ToolPhase.call,
+      } as const
+      await handler(
+        { type: MothershipStreamV1EventType.tool, scope, payload: { ...payload, partial: true } },
+        context,
+        execContext,
+        {}
+      )
+      await handler(
+        {
+          type: MothershipStreamV1EventType.tool,
+          scope,
+          payload: {
+            ...payload,
+            arguments: { code: 'return 1' },
+            activityDescription: '  Checking   the project setup  ',
+          },
+        },
+        context,
+        execContext,
+        {}
+      )
+      const tool = context.toolCalls.get(payload.toolCallId)
+      expect(tool).toMatchObject({
+        activityDescription: 'Checking the project setup',
+        displayTitle: 'Checking the project setup',
+        params: { code: 'return 1' },
+      })
+      if (lane === 'subagent') {
+        expect(context.subAgentToolCalls['activity-parent'][0]).toBe(tool)
+      }
+      expect(executeTool).not.toHaveBeenCalled()
+    }
+  )
+
+  it.each(['executing', 'awaiting_approval', 'success'] as const)(
+    'captures late activity metadata for a %s call without reopening or executing it',
+    async (status) => {
+      context.toolCalls.set('activity-late', { id: 'activity-late', name: 'read', status })
+      const event: StreamEvent = {
+        type: MothershipStreamV1EventType.tool,
+        payload: {
+          phase: MothershipStreamV1ToolPhase.call,
+          executor: MothershipStreamV1ToolExecutor.go,
+          mode: MothershipStreamV1ToolMode.sync,
+          toolCallId: 'activity-late',
+          toolName: 'read',
+          arguments: { path: 'WORKSPACE.md' },
+          activityDescription: 'Checking the project setup',
+        },
+      }
+      await sseHandlers.tool(event, context, execContext, {})
+      await sseHandlers.tool(
+        { ...event, payload: { ...event.payload, activityDescription: 'Reading something else' } },
+        context,
+        execContext,
+        {}
+      )
+      expect(context.toolCalls.get('activity-late')).toMatchObject({
+        status,
+        activityDescription: 'Checking the project setup',
+        displayTitle: 'Checking the project setup',
+      })
+      expect(executeTool).not.toHaveBeenCalled()
+    }
+  )
+
   it('rebinds a gateway call to the resolved integration operation and branded activity', async () => {
     isSimExecuted.mockReturnValue(false)
     executeTool.mockResolvedValueOnce({ success: true, output: { emails: [] } })
diff --git a/apps/sim/lib/copilot/request/handlers/tool.ts b/apps/sim/lib/copilot/request/handlers/tool.ts
index cc88538a292..9e563ecd6e8 100644
--- a/apps/sim/lib/copilot/request/handlers/tool.ts
+++ b/apps/sim/lib/copilot/request/handlers/tool.ts
@@ -47,7 +47,10 @@ import { getToolEntry, isSimExecuted } from '@/lib/copilot/tool-executor'
 import { isToolHiddenInUi } from '@/lib/copilot/tools/client/hidden-tools'
 import { isUserLocalVfsToolCall } from '@/lib/copilot/tools/local-filesystem'
 import { extractStreamingStringArgument } from '@/lib/copilot/tools/streaming-args'
-import { getToolDisplayTitle } from '@/lib/copilot/tools/tool-display'
+import {
+  getToolDisplayTitle,
+  normalizeToolActivityDescription,
+} from '@/lib/copilot/tools/tool-display'
 import { isWorkflowToolName, resolveWorkflowToolTargetId } from '@/lib/copilot/tools/workflow-tools'
 import { getBlockByToolName } from '@/blocks/registry'
 import type { ToolScope } from './types'
@@ -71,6 +74,10 @@ const logger = createLogger('CopilotToolHandler')
 
 function applyToolDisplay(toolCall: ToolCallState | undefined): void {
   if (!toolCall?.name) return
+  if (toolCall.activityDescription) {
+    toolCall.displayTitle = toolCall.activityDescription
+    return
+  }
   // Integration rows show only the model-authored activity phrase; the trusted
   // integration branding is the icon, derived client-side from the operation
   // name (or streamed toolId) via the block registry. With no description yet,
@@ -439,7 +446,11 @@ async function handleCallPhase(
   const isGenerating = data.status === TOOL_CALL_STATUS.generating
   const isPartial = data.partial === true || isGenerating
   const existing = context.toolCalls.get(toolCallId)
-  if (existing) existing.agentId ??= agentId
+  const activityDescription = normalizeToolActivityDescription(data.activityDescription)
+  if (existing) {
+    existing.agentId ??= agentId
+    existing.activityDescription ??= activityDescription
+  }
   const isSubagent = scope === 'subagent'
   const ui = getToolCallUI(data)
 
@@ -486,10 +497,21 @@ async function handleCallPhase(
       agentId,
       ui,
       spanIdentity,
-      !isPartial
+      !isPartial,
+      activityDescription
     )
   } else {
-    registerMainToolCall(context, toolCallId, toolName, args, existing, agentId, ui, !isPartial)
+    registerMainToolCall(
+      context,
+      toolCallId,
+      toolName,
+      args,
+      existing,
+      agentId,
+      ui,
+      !isPartial,
+      activityDescription
+    )
   }
 
   if (isPartial) return
@@ -588,7 +610,8 @@ function registerSubagentToolCall(
   agentId: string,
   ui: { title?: string; phaseLabel?: string; hidden?: boolean },
   spanIdentity: { spanId?: string; parentSpanId?: string },
-  finalized: boolean
+  finalized: boolean,
+  activityDescription?: string
 ): void {
   if (!context.subAgentToolCalls[parentToolCallId]) {
     context.subAgentToolCalls[parentToolCallId] = []
@@ -607,6 +630,7 @@ function registerSubagentToolCall(
       name: toolName,
       status: 'pending',
       agentId,
+      ...(activityDescription ? { activityDescription } : {}),
       params: args,
       startTime: Date.now(),
     }
@@ -628,6 +652,7 @@ function registerSubagentToolCall(
   const existingSubagentToolCall = subagentToolCalls.find((tc) => tc.id === toolCallId)
   if (existingSubagentToolCall) {
     existingSubagentToolCall.agentId ??= agentId
+    existingSubagentToolCall.activityDescription ??= activityDescription
     if (!rebindResolvedIntegrationCall(existingSubagentToolCall, toolName, args)) {
       updateToolCallFromFrame(existingSubagentToolCall, toolName, args, finalized)
     }
@@ -645,7 +670,8 @@ function registerMainToolCall(
   existing: ToolCallState | undefined,
   agentId: string,
   ui: { title?: string; phaseLabel?: string; hidden?: boolean },
-  finalized: boolean
+  finalized: boolean,
+  activityDescription?: string
 ): void {
   const hideFromUi = isToolHiddenInUi(toolName) || ui.hidden === true
   if (existing) {
@@ -669,6 +695,7 @@ function registerMainToolCall(
       name: toolName,
       status: 'pending',
       agentId,
+      ...(activityDescription ? { activityDescription } : {}),
       params: args,
       startTime: Date.now(),
     }
diff --git a/apps/sim/lib/copilot/request/types.ts b/apps/sim/lib/copilot/request/types.ts
index 5a720b5bb99..1afdf77e4b8 100644
--- a/apps/sim/lib/copilot/request/types.ts
+++ b/apps/sim/lib/copilot/request/types.ts
@@ -29,6 +29,8 @@ export interface ToolCallState {
   /** Bounded registry ID of the agent that invoked this tool. */
   agentId?: string
   displayTitle?: string
+  /** Model-authored activity text, separate from executable tool arguments. */
+  activityDescription?: string
   /** Model-authored activity text for a gateway-resolved integration call. */
   integrationDescription?: string
   /** Accumulated partial JSON of the arguments while the model streams them. */
diff --git a/apps/sim/lib/copilot/tools/tool-display.test.ts b/apps/sim/lib/copilot/tools/tool-display.test.ts
index 9eae8f49e93..9c8a7d97f94 100644
--- a/apps/sim/lib/copilot/tools/tool-display.test.ts
+++ b/apps/sim/lib/copilot/tools/tool-display.test.ts
@@ -2,6 +2,7 @@
  * @vitest-environment node
  */
 import { describe, expect, it } from 'vitest'
+import { MOTHERSHIP_STREAM_V1_SCHEMA } from '@/lib/copilot/generated/mothership-stream-v1-schema'
 import {
   FfmpegOperationValues,
   ManageKnowledgeBaseOperationValues,
@@ -20,6 +21,7 @@ import {
   getWaitCountdownTitle,
   humanizeToolName,
   mvDisplayVerb,
+  normalizeToolActivityDescription,
 } from '@/lib/copilot/tools/tool-display'
 
 function representativeToolArgs(entry: ToolCatalogEntry): Record<string, unknown> {
@@ -816,3 +818,28 @@ describe('getToolStatusDisplayTitle for skipped and interrupted calls', () => {
     expect(getToolStatusDisplayTitle('Checks', 'skipped')).toBe('Skipped: Checks')
   })
 })
+
+describe('normalizeToolActivityDescription', () => {
+  it('matches the bound published by the producer contract', () => {
+    expect(MOTHERSHIP_STREAM_V1_SCHEMA).toHaveProperty(
+      '$defs.MothershipStreamV1ToolCallDescriptor.properties.activityDescription.maxLength',
+      160
+    )
+  })
+
+  it('normalizes a phrase without rewriting its meaning', () => {
+    expect(
+      normalizeToolActivityDescription('\uFEFF Checking\n\tthe\u00a0latest\u0085invoices  ')
+    ).toBe('Checking the latest invoices')
+  })
+
+  it.each([undefined, null, false, 42, {}, [], '', ' \n\t ', 'a'.repeat(161)])(
+    'ignores an invalid description: %j',
+    (value) => expect(normalizeToolActivityDescription(value)).toBeUndefined()
+  )
+
+  it('counts Unicode codepoints after whitespace normalization', () => {
+    expect(normalizeToolActivityDescription(`  ${'🧪'.repeat(160)}  `)).toBe('🧪'.repeat(160))
+    expect(normalizeToolActivityDescription('🧪'.repeat(161))).toBeUndefined()
+  })
+})
diff --git a/apps/sim/lib/copilot/tools/tool-display.ts b/apps/sim/lib/copilot/tools/tool-display.ts
index da4f01ddc7a..8bb48e1a54c 100644
--- a/apps/sim/lib/copilot/tools/tool-display.ts
+++ b/apps/sim/lib/copilot/tools/tool-display.ts
@@ -4,17 +4,23 @@ import { stripVersionSuffix, truncate } from '@sim/utils/string'
 /**
  * Single source of truth for copilot tool-call display titles.
  *
- * The mothership (Go) no longer emits any presentation metadata on the stream —
- * tool-call titles are derived entirely here, keyed by tool name (plus arguments
- * for the dynamic cases). The live client render layer (see
+ * Model-authored invocation descriptions take precedence when available. Fallback
+ * titles are derived here from the tool name and arguments. The live client render layer (see
  * `home/hooks/stream/stream-helpers.ts`) wraps this with workspace/block-name
  * enrichment for the run_* tools; every other surface (server persistence,
  * transcript replay, fallback rendering) calls `getToolDisplayTitle` directly.
  *
  * Icons are likewise client-owned — see `getAgentIcon` in the message-content
- * utils. Nothing about tool presentation lives on the Go side anymore.
+ * utils. Tool status, icons, and fallback wording remain deterministic.
  */
 
+/** Normalizes optional model-authored activity text using the producer's Unicode bound. */
+export function normalizeToolActivityDescription(value: unknown): string | undefined {
+  if (typeof value !== 'string') return undefined
+  const description = value.replace(/[\p{White_Space}\uFEFF]+/gu, ' ').trim()
+  return description && Array.from(description).length <= 160 ? description : undefined
+}
+
 type ToolArgs = Record<string, unknown> | undefined
 
 export const CONTEXT_COMPACTION_DISPLAY_TITLE = 'Summarizing context'
@@ -1439,8 +1445,12 @@ function statesTerminalOutcome(title: string): boolean {
 }
 
 /** Apply one terminal outcome prefix while preserving already-resolved titles. */
-function getToolOutcomeTitle(title: string, outcome: 'Failed' | 'Stopped' | 'Skipped'): string {
-  if (statesTerminalOutcome(title)) return title
+function getToolOutcomeTitle(
+  title: string,
+  outcome: 'Failed' | 'Stopped' | 'Skipped',
+  preserveExistingOutcome = true
+): string {
+  if (preserveExistingOutcome && statesTerminalOutcome(title)) return title
   const firstWord = firstWordOf(title)
   if (COMPLETED_VERB_REWRITES[firstWord]) {
     return `${outcome} ${firstWord.charAt(0).toLowerCase()}${firstWord.slice(1)}${title.slice(firstWord.length)}`
@@ -1472,16 +1482,21 @@ export function getToolStoppedTitle(title: string): string {
 export function getToolStatusDisplayTitle(
   title: string,
   status: string,
-  toolName?: string
+  toolName?: string,
+  activityDescription?: string
 ): string {
+  const description = normalizeToolActivityDescription(activityDescription)
+  title = description ?? title
   if (status === 'success' && toolName === 'browser_request_takeover') {
     return 'Resumed browser control'
   }
   if (status === 'success') return getToolCompletedTitle(title) ?? title
-  if (status === 'error' || status === 'rejected') return getToolFailedTitle(title)
+  if (status === 'error' || status === 'rejected') {
+    return getToolOutcomeTitle(title, 'Failed', !description)
+  }
   if (status === 'cancelled' || status === 'aborted' || status === 'interrupted') {
-    return getToolStoppedTitle(title)
+    return getToolOutcomeTitle(title, 'Stopped', !description)
   }
-  if (status === 'skipped') return getToolOutcomeTitle(title, 'Skipped')
+  if (status === 'skipped') return getToolOutcomeTitle(title, 'Skipped', !description)
   return title
 }

From b23f54858bdace254e96f6d0055dab7e13ba472c Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 12 Sep 2026 20:24:27 -0700
Subject: [PATCH 2/3] chore(copilot): remove unused outcome title wrappers

---
 apps/sim/lib/copilot/tools/tool-display.ts | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/apps/sim/lib/copilot/tools/tool-display.ts b/apps/sim/lib/copilot/tools/tool-display.ts
index 8bb48e1a54c..520e97b0462 100644
--- a/apps/sim/lib/copilot/tools/tool-display.ts
+++ b/apps/sim/lib/copilot/tools/tool-display.ts
@@ -1448,7 +1448,7 @@ function statesTerminalOutcome(title: string): boolean {
 function getToolOutcomeTitle(
   title: string,
   outcome: 'Failed' | 'Stopped' | 'Skipped',
-  preserveExistingOutcome = true
+  preserveExistingOutcome: boolean
 ): string {
   if (preserveExistingOutcome && statesTerminalOutcome(title)) return title
   const firstWord = firstWordOf(title)
@@ -1458,21 +1458,6 @@ function getToolOutcomeTitle(
   return `${outcome}: ${title}`
 }
 
-/**
- * Rewrite a resolved display title for a FAILED tool call. A gerund title
- * becomes "Failed <gerund>…" ("Searching for X" → "Failed searching for X");
- * anything else gets a "Failed: " prefix. Without this, an errored row kept
- * its present-tense activity title verbatim and read as still running.
- */
-export function getToolFailedTitle(title: string): string {
-  return getToolOutcomeTitle(title, 'Failed')
-}
-
-/** Rewrite a resolved display title for a CANCELLED tool call ("Stopped <gerund>…"). */
-export function getToolStoppedTitle(title: string): string {
-  return getToolOutcomeTitle(title, 'Stopped')
-}
-
 /**
  * Resolve the final title for a tool status at a rendering boundary. Persisted
  * and live snapshots intentionally keep the present-tense activity title so a

From f8bfcd38d57c73f01d070d2dbd41bc249d350a4a Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 12 Sep 2026 20:36:34 -0700
Subject: [PATCH 3/3] fix(copilot): keep model activity outcomes authoritative

---
 .../agent-group/tool-call-item.test.tsx       |  3 ++-
 .../lib/copilot/tools/tool-display.test.ts    | 22 ++++++++++++++++++
 apps/sim/lib/copilot/tools/tool-display.ts    | 23 +++++++++++++------
 3 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx
index a67ea10d4de..52e9489811d 100644
--- a/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.test.tsx
@@ -128,7 +128,8 @@ describe('ToolCallItem', () => {
       />
     )
 
-    expect(markup).toContain('Failed: Stopped checking invoices')
+    expect(markup).toContain('Failed checking invoices')
+    expect(markup).not.toContain('Stopped checking invoices')
   })
 
   it('defensively applies the completed verb for every successful tool row', () => {
diff --git a/apps/sim/lib/copilot/tools/tool-display.test.ts b/apps/sim/lib/copilot/tools/tool-display.test.ts
index 9c8a7d97f94..e79e95bebff 100644
--- a/apps/sim/lib/copilot/tools/tool-display.test.ts
+++ b/apps/sim/lib/copilot/tools/tool-display.test.ts
@@ -843,3 +843,25 @@ describe('normalizeToolActivityDescription', () => {
     expect(normalizeToolActivityDescription('🧪'.repeat(161))).toBeUndefined()
   })
 })
+
+describe('model-authored activity outcomes', () => {
+  it.each([
+    ['success', 'Checking invoices', 'Checked invoices'],
+    ['success', 'Check invoices', 'Completed: Check invoices'],
+    ['success', 'Reconciling invoices', 'Completed: Reconciling invoices'],
+    ['success', 'Revisando facturas', 'Completed: Revisando facturas'],
+    ['success', 'Stopped checking invoices', 'Completed checking invoices'],
+    ['success', 'Completed: Check invoices', 'Completed: Check invoices'],
+    ['error', 'Failed: Fetching invoices', 'Failed: Fetching invoices'],
+    ['error', 'Stopped checking invoices', 'Failed checking invoices'],
+    ['error', 'Completed checking invoices', 'Failed checking invoices'],
+    ['rejected', 'Failed checking invoices', 'Failed checking invoices'],
+    ['cancelled', 'Stopped reading notes', 'Stopped reading notes'],
+    ['interrupted', 'Completed: Check invoices', 'Stopped: Check invoices'],
+    ['skipped', 'Failed: Checking invoices', 'Skipped: Checking invoices'],
+  ])('projects %s once onto "%s"', (status, description, expected) => {
+    const title = getToolStatusDisplayTitle('Fallback', status, 'read', description)
+    expect(title).toBe(expected)
+    expect(getToolStatusDisplayTitle(title, status, 'read', description)).toBe(expected)
+  })
+})
diff --git a/apps/sim/lib/copilot/tools/tool-display.ts b/apps/sim/lib/copilot/tools/tool-display.ts
index 520e97b0462..3c716f61503 100644
--- a/apps/sim/lib/copilot/tools/tool-display.ts
+++ b/apps/sim/lib/copilot/tools/tool-display.ts
@@ -1408,11 +1408,8 @@ const COMPLETED_VERB_REWRITES: Record<string, string> = {
 /**
  * Rewrite a resolved display title to its past-tense form for a successfully
  * completed tool call (e.g. "Querying logs for X" -> "Queried logs for X").
- * Operates on the already-resolved title so enriched and persisted titles both
- * work. Returns undefined when the title has no leading gerund rewrite — the
- * caller keeps the original. Integration gateway descriptions are base-form
- * verb phrases ("Read recent emails") whose first word never matches a gerund
- * key, so they intentionally pass through unchanged.
+ * Returns undefined when no leading gerund rewrite is known; status formatting
+ * handles the fallback for model-authored and legacy titles.
  */
 export function getToolCompletedTitle(title: string): string | undefined {
   const spaceIndex = title.indexOf(' ')
@@ -1447,11 +1444,18 @@ function statesTerminalOutcome(title: string): boolean {
 /** Apply one terminal outcome prefix while preserving already-resolved titles. */
 function getToolOutcomeTitle(
   title: string,
-  outcome: 'Failed' | 'Stopped' | 'Skipped',
+  outcome: 'Completed' | 'Failed' | 'Stopped' | 'Skipped',
   preserveExistingOutcome: boolean
 ): string {
   if (preserveExistingOutcome && statesTerminalOutcome(title)) return title
   const firstWord = firstWordOf(title)
+  const statedOutcome = firstWord.replace(/:$/, '')
+  if (
+    !preserveExistingOutcome &&
+    (TERMINAL_TITLE_PREFIXES.has(statedOutcome) || statedOutcome === 'Completed')
+  ) {
+    return outcome + title.slice(statedOutcome.length)
+  }
   if (COMPLETED_VERB_REWRITES[firstWord]) {
     return `${outcome} ${firstWord.charAt(0).toLowerCase()}${firstWord.slice(1)}${title.slice(firstWord.length)}`
   }
@@ -1475,7 +1479,12 @@ export function getToolStatusDisplayTitle(
   if (status === 'success' && toolName === 'browser_request_takeover') {
     return 'Resumed browser control'
   }
-  if (status === 'success') return getToolCompletedTitle(title) ?? title
+  if (status === 'success') {
+    return (
+      getToolCompletedTitle(title) ??
+      (description ? getToolOutcomeTitle(title, 'Completed', false) : title)
+    )
+  }
   if (status === 'error' || status === 'rejected') {
     return getToolOutcomeTitle(title, 'Failed', !description)
   }