fix(vscode): preserve cached reasoning variants

.changeset/quiet-variants-cache.md

@@ -0,0 +1,5 @@
+---
+"kilo-code": patch
+---
+
+Preserve cached reasoning variants when starting new VS Code sessions.

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

@@ -66,15 +66,24 @@ describe("session variants", () => {
 
   it("persists an explicit default selection", () => {
     const state = setup()
+    state.selections["agent/code/anthropic/claude-sonnet-4"] = "high"
     state.variants.select(undefined)
     expect(state.selections).toEqual({ "agent/code/anthropic/claude-sonnet-4": "" })
     expect(state.variants.current()).toBeUndefined()
     expect(state.messages).toEqual([{ type: "persistVariant", key: "agent/code/anthropic/claude-sonnet-4", value: "" }])
   })
 
-  it("carries the model default across model changes", () => {
-    const state = setup()
-    state.variants.carry(model, undefined, "code")
-    expect(state.selections).toEqual({ "agent/code/anthropic/claude-sonnet-4": "" })
+  it("does not shadow a cached variant when carrying the model default", () => {
+    const global = setup()
+    global.selections["agent/code/anthropic/claude-sonnet-4"] = "high"
+    global.variants.carry(model, undefined, "code")
+    expect(global.selections).toEqual({ "agent/code/anthropic/claude-sonnet-4": "high" })
+    expect(global.messages).toEqual([])
+
+    const session = setup("session-a")
+    session.selections["agent/code/anthropic/claude-sonnet-4"] = "high"
+    session.variants.carry(model, undefined, "code", "session-a")
+    expect(session.selections).toEqual({ "agent/code/anthropic/claude-sonnet-4": "high" })
+    expect(session.variants.current()).toBe("high")
   })
 })

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

@@ -53,7 +53,10 @@ export function createSessionVariants(options: Options) {
   const carry = (selection: ModelSelection, value: string | undefined, name: string, sessionID?: string) => {
     const list = Object.keys(options.find(selection)?.variants ?? {})
     if (list.length === 0) return
-    const next = value === undefined ? DEFAULT_VARIANT : preserveVariant(value, list)
+    // An absent value means the model default, not an explicit user choice.
+    // Do not write a default sentinel here because it would shadow a cached
+    // agent-level variant when this selection is resolved for a new session.
+    const next = preserveVariant(value, list)
     if (next === undefined) return
     const key = variantKey(selection, name, sessionID)
     options.set(key, next)