Merge pull request #13430 from Kilo-Org/investigate-duplicate-sse-rendering

fix(vscode): prevent duplicate reasoning with subagent inspectors

.changeset/isolated-reasoning-streams.md

@@ -0,0 +1,5 @@
+---
+"kilo-code": patch
+---
+
+Prevent duplicate reasoning and response text while subagent sessions are open.

packages/kilo-vscode/tests/unit/session-parts.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "bun:test"
-import { mergeOptimisticPart, mergeParts, sameParts } from "../../webview-ui/src/context/session-parts"
+import { createStore, produce } from "solid-js/store"
+import { isolate, mergeOptimisticPart, mergeParts, sameParts } from "../../webview-ui/src/context/session-parts"
 import type { Part } from "../../webview-ui/src/types/messages"
 
 function text(id: string, value: string, time: { start?: number; end?: number } = {}): Part {
@@ -20,6 +21,39 @@ function value(parts: Part[], id: string) {
   return part.text
 }
 
+describe("isolate", () => {
+  it("keeps shared reasoning snapshots independent across session stores", () => {
+    const shared = {
+      id: "r1",
+      messageID: "m1",
+      type: "reasoning",
+      text: "Thinking",
+      time: { start: 1 },
+    } satisfies Part
+    const [first, setFirst] = createStore({ parts: [shared].map(isolate) })
+    const [second, setSecond] = createStore({ parts: [shared].map(isolate) })
+
+    setFirst(
+      "parts",
+      produce((parts) => {
+        const part = parts[0]
+        if (part?.type === "reasoning") part.text += " once"
+      }),
+    )
+    setSecond(
+      "parts",
+      produce((parts) => {
+        const part = parts[0]
+        if (part?.type === "reasoning") part.text += " once"
+      }),
+    )
+
+    expect(first.parts[0]?.type === "reasoning" && first.parts[0].text).toBe("Thinking once")
+    expect(second.parts[0]?.type === "reasoning" && second.parts[0].text).toBe("Thinking once")
+    expect(shared.text).toBe("Thinking")
+  })
+})
+
 describe("mergeParts", () => {
   it("keeps a final streamed tail part created after the reconcile snapshot started", () => {
     const parts = mergeParts(
@@ -120,6 +154,31 @@ describe("mergeOptimisticPart", () => {
     expect(result.parts.map((part) => part.id)).toEqual(["client-text", "server-file"])
     expect(result.replaced).toBe("client-file")
   })
+
+  it("keeps streamed deltas independent across session stores", () => {
+    const shared = text("server", "start")
+    const [first, setFirst] = createStore({ parts: mergeOptimisticPart([], new Set(), shared).parts })
+    const [second, setSecond] = createStore({ parts: mergeOptimisticPart([], new Set(), shared).parts })
+
+    setFirst(
+      "parts",
+      produce((parts) => {
+        const part = parts[0]
+        if (part?.type === "text") part.text += " chunk"
+      }),
+    )
+    setSecond(
+      "parts",
+      produce((parts) => {
+        const part = parts[0]
+        if (part?.type === "text") part.text += " chunk"
+      }),
+    )
+
+    expect(value(first.parts, "server")).toBe("start chunk")
+    expect(value(second.parts, "server")).toBe("start chunk")
+    expect(value([shared], "server")).toBe("start")
+  })
 })
 
 describe("sameParts", () => {

packages/kilo-vscode/webview-ui/src/context/session-parts.ts

@@ -1,5 +1,9 @@
 import type { Part } from "../types/messages"
 
+export function isolate(part: Part): Part {
+  return { ...part }
+}
+
 function stream(part: Part): part is Extract<Part, { type: "text" | "reasoning" }> {
   return part.type === "text" || part.type === "reasoning"
 }
@@ -27,10 +31,11 @@ export function sameParts(local: Part[] = [], snapshot: Part[] = []): boolean {
 
 export function mergeOptimisticPart(current: Part[], ids: ReadonlySet<string>, part: Part) {
   const index = current.findIndex((item) => ids.has(item.id) && item.type === part.type)
-  if (index < 0) return { parts: [...current, part] }
+  const copy = isolate(part)
+  if (index < 0) return { parts: [...current, copy] }
   const old = current[index]!
   const next = current.slice()
-  next[index] = part
+  next[index] = copy
   return { parts: next, replaced: old.id }
 }
 

packages/kilo-vscode/webview-ui/src/context/session.tsx

@@ -79,7 +79,7 @@ import { getAgentModel } from "./session-model-store"
 import { resolveMessagePrefs } from "./session-preferences"
 import { errorIDs, preserveSessionErrors, withoutResolvedSessionErrors } from "./session-errors"
 import { PartStash } from "./part-stash"
-import { mergeOptimisticPart, mergeParts } from "./session-parts"
+import { isolate, mergeOptimisticPart, mergeParts } from "./session-parts"
 import { mergeMessages, sameReconcileShape } from "./session-merge"
 import { state as todoState } from "./todo-revert"
 import { sessionVariantKeys, transferVariants, variantKey } from "./session-variant-store"
@@ -1457,7 +1457,7 @@ export const SessionProvider: ParentComponent = (props) => {
       const cutoff = Math.max(0, messages.length - 15)
       for (let i = 0; i < messages.length; i++) {
         const msg = messages[i]!
-        const parts = msg.parts ?? []
+        const parts = msg.parts?.map(isolate) ?? []
         if (mode === "reconcile" && store.parts[msg.id] && !optimisticParts.has(msg.id)) {
           const merged = mergeParts(store.parts[msg.id], parts, input.since ?? Number.POSITIVE_INFINITY)
           setStore("parts", msg.id, reconcile(merged, { key: "id" }))
@@ -1546,7 +1546,7 @@ export const SessionProvider: ParentComponent = (props) => {
     if (message.parts && message.parts.length > 0) {
       optimisticParts.delete(message.id)
       stash.remove(message.id)
-      setStore("parts", message.id, message.parts)
+      setStore("parts", message.id, message.parts.map(isolate))
     }
     rebuildToolParts(message.sessionID, store.messages[message.sessionID] ?? [])
   }
@@ -1624,7 +1624,7 @@ export const SessionProvider: ParentComponent = (props) => {
           }
         } else {
           // Add new part
-          list.push(part)
+          list.push(isolate(part))
         }
       }),
     )
@@ -2067,7 +2067,7 @@ export const SessionProvider: ParentComponent = (props) => {
       setStore("messages", key, messages)
       for (const msg of messages) {
         if (msg.parts && msg.parts.length > 0) {
-          setStore("parts", msg.id, msg.parts)
+          setStore("parts", msg.id, msg.parts.map(isolate))
         }
       }
       rebuildToolParts(key, messages)