fix(sync): deduplicate overlapping delta after coalesced part.updated (#916)

* fix: hide archived section and empty folders when no sessions remain - Only push archived group in useSessionGrouping when there are archived sessions, preventing an empty archived section from rendering - Hide empty folders in archived bucket via shouldKeepFolder check in SessionGroupSection (folders with no sessions and no content in children are filtered out) - Always filter folders through shouldKeepFolder, not just during search * perf: memoize archived folder filtering * fix(sync): deduplicate overlapping delta after coalesced part.updated When message.part.updated coalesces in the event pipeline and a message.part.delta for the same part arrives in the same flush window, the reducer appends the delta verbatim to the already-complete field value, producing duplicated text in tool output and assistant messages. Add targeted overlap reconciliation: only when a part.updated replaces an existing part with overlapping string content, mark the next delta for that field as dedupe-eligible. Normal streaming deltas remain untouched (pure append). Covers four cases: - Full overlap: delta already present -> no-op - Partial overlap: only non-overlapping suffix appended - No overlap: unchanged append behavior - Legitimate repeated output (ha + ha -> haha): preserved --------- Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>
2026-04-15 10:12:30 +03:00
parent 9908f2dc9c
commit ea5c19e934
2 changed files with 199 additions and 2 deletions
@@ -0,0 +1,154 @@
+import { describe, expect, it } from 'bun:test'
+import { applyDirectoryEvent } from '../event-reducer'
+import { INITIAL_STATE } from '../types'
+
+describe('applyDirectoryEvent', () => {
+  it('does not duplicate overlapping delta text after a newer part.updated replaces an older one', () => {
+    const state = structuredClone(INITIAL_STATE)
+    const messageID = 'msg-1'
+    const partID = 'part-1'
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.updated',
+      properties: {
+        part: {
+          id: partID,
+          type: 'text',
+          messageID,
+          text: 'Fix typo in ToolOutputDialog — ',
+        },
+      },
+    })
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.updated',
+      properties: {
+        part: {
+          id: partID,
+          type: 'text',
+          messageID,
+          text: 'Fix typo in ToolOutputDialog — toolFailedToReadDiagram vs toolFailedReadDiagram • Let me fix it.',
+        },
+      },
+    })
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.delta',
+      properties: {
+        messageID,
+        partID,
+        field: 'text',
+        delta: 'toolFailedToReadDiagram vs toolFailedReadDiagram • Let me fix it.',
+      },
+    })
+
+    expect(state.part[messageID]).toHaveLength(1)
+    expect(state.part[messageID]?.[0]?.text).toBe(
+      'Fix typo in ToolOutputDialog — toolFailedToReadDiagram vs toolFailedReadDiagram • Let me fix it.',
+    )
+  })
+
+  it('appends only the non-overlapping suffix of a streaming delta', () => {
+    const state = structuredClone(INITIAL_STATE)
+    const messageID = 'msg-2'
+    const partID = 'part-2'
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.updated',
+      properties: {
+        part: {
+          id: partID,
+          type: 'text',
+          messageID,
+          text: 'toolFailedToReadDiagram vs toolFailedRead',
+        },
+      },
+    })
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.updated',
+      properties: {
+        part: {
+          id: partID,
+          type: 'text',
+          messageID,
+          text: 'toolFailedToReadDiagram vs toolFailedReadDiagra',
+        },
+      },
+    })
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.delta',
+      properties: {
+        messageID,
+        partID,
+        field: 'text',
+        delta: 'Diagram • Let me fix it.',
+      },
+    })
+
+    expect(state.part[messageID]?.[0]?.text).toBe(
+      'toolFailedToReadDiagram vs toolFailedReadDiagram • Let me fix it.',
+    )
+  })
+
+  it('appends a non-overlapping delta unchanged', () => {
+    const state = structuredClone(INITIAL_STATE)
+    const messageID = 'msg-3'
+    const partID = 'part-3'
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.updated',
+      properties: {
+        part: {
+          id: partID,
+          type: 'text',
+          messageID,
+          text: 'PR comment done — ',
+        },
+      },
+    })
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.delta',
+      properties: {
+        messageID,
+        partID,
+        field: 'text',
+        delta: 'Let me fix it.',
+      },
+    })
+
+    expect(state.part[messageID]?.[0]?.text).toBe('PR comment done — Let me fix it.')
+  })
+
+  it('preserves legitimate repeated output when no updated-to-delta dedupe window is active', () => {
+    const state = structuredClone(INITIAL_STATE)
+    const messageID = 'msg-4'
+    const partID = 'part-4'
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.updated',
+      properties: {
+        part: {
+          id: partID,
+          type: 'text',
+          messageID,
+          text: 'ha',
+        },
+      },
+    })
+
+    applyDirectoryEvent(state, {
+      type: 'message.part.delta',
+      properties: {
+        messageID,
+        partID,
+        field: 'text',
+        delta: 'ha',
+      },
+    })
+
+    expect(state.part[messageID]?.[0]?.text).toBe('haha')
+  })
+})