feat(web): make grouped tool summaries specific (#1134)

web/src/chat/toolGroups.test.ts

@@ -141,6 +141,33 @@ describe('isEligibleForToolGrouping', () => {
     })
 })
 
+describe('Codex activity headings', () => {
+    it('associates only an immediately preceding reasoning heading', () => {
+        const reasoning = makeToolBlock('reasoning-1', 'CodexReasoning', { title: 'Inspecting authentication' })
+        const visible = buildVisibleChatBlocks([
+            reasoning,
+            makeToolBlock('read-1', 'Read', { file_path: 'auth.ts' }),
+            makeToolBlock('read-2', 'Read', { file_path: 'session.ts' }),
+        ], { hasMoreMessages: false })
+
+        expect(visible).toHaveLength(2)
+        expect(isToolGroupBlock(visible[1])).toBe(true)
+        expect(isToolGroupBlock(visible[1]) ? visible[1].activityTitle : null).toBe('Inspecting authentication')
+    })
+
+    it('does not carry a heading across a text boundary', () => {
+        const visible = buildVisibleChatBlocks([
+            makeToolBlock('reasoning-1', 'CodexReasoning', { title: 'Inspecting authentication' }),
+            makeTextBlock('text-boundary'),
+            makeToolBlock('read-1', 'Read', { file_path: 'auth.ts' }),
+            makeToolBlock('read-2', 'Read', { file_path: 'session.ts' }),
+        ], { hasMoreMessages: false })
+
+        const group = visible.find(isToolGroupBlock)
+        expect(group?.activityTitle).toBeNull()
+    })
+})
+
 describe('buildVisibleChatBlocks', () => {
     it('groups contiguous eligible root tool cards', () => {
         const visible = buildVisibleChatBlocks([

web/src/chat/toolGroups.ts

@@ -30,6 +30,7 @@ export type ToolGroupBlock = {
     defaultOpen: boolean
     historyState: 'complete' | 'needs-older-history'
     needsOlderHistory: boolean
+    activityTitle?: string | null
     summary: ToolGroupSummary
 }
 
@@ -258,6 +259,11 @@ export function buildVisibleChatBlocks(
 
         const startsAtOldestVisibleBoundary = visibleBlocks.length === 0
         const needsOlderHistory = options.hasMoreMessages && startsAtOldestVisibleBoundary
+        const previousBlock = visibleBlocks.at(-1)
+        const activityTitle = previousBlock?.kind === 'tool-call'
+            && previousBlock.tool.name === 'CodexReasoning'
+            ? getInputStringAny(previousBlock.tool.input, ['title'])
+            : null
         visibleBlocks.push({
             kind: 'tool-group',
             id: createToolGroupId(tools, needsOlderHistory, previousGroups),
@@ -269,6 +275,7 @@ export function buildVisibleChatBlocks(
             defaultOpen: false,
             historyState: needsOlderHistory ? 'needs-older-history' : 'complete',
             needsOlderHistory,
+            activityTitle,
             summary: summarizeToolGroup(tools)
         })
         index = cursor - 1