diff --git a/packages/kilo-vscode/src/KiloProvider.ts b/packages/kilo-vscode/src/KiloProvider.ts
index f09622232..a99dcbb99 100644
--- a/packages/kilo-vscode/src/KiloProvider.ts
+++ b/packages/kilo-vscode/src/KiloProvider.ts
@@ -285,6 +285,7 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
             message.providerID,
             message.modelID,
             message.agent,
+            message.variant,
             files,
           )
           break
@@ -439,6 +440,23 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
         case "telemetry":
           TelemetryProxy.capture(message.event, message.properties)
           break
+        case "persistVariant": {
+          const stored =
+            this.extensionContext?.globalState.get<Record<string, string | undefined>>("variantSelections") ?? {}
+          if (message.value === undefined) {
+            delete stored[message.key]
+          } else {
+            stored[message.key] = message.value
+          }
+          await this.extensionContext?.globalState.update("variantSelections", stored)
+          break
+        }
+        case "requestVariants": {
+          const variants =
+            this.extensionContext?.globalState.get<Record<string, string | undefined>>("variantSelections") ?? {}
+          this.postMessage({ type: "variantsLoaded", variants })
+          break
+        }
       }
     })
   }
@@ -1002,6 +1020,7 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
     providerID?: string,
     modelID?: string,
     agent?: string,
+    variant?: string,
     files?: Array<{ mime: string; url: string }>,
   ): Promise<void> {
     if (!this.httpClient) {
@@ -1057,6 +1076,7 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
         providerID,
         modelID,
         agent,
+        variant,
       })
     } catch (error) {
       console.error("[Kilo New] KiloProvider: Failed to send message:", error)
diff --git a/packages/kilo-vscode/src/services/cli-backend/http-client.ts b/packages/kilo-vscode/src/services/cli-backend/http-client.ts
index fcbb2646a..8892525c4 100644
--- a/packages/kilo-vscode/src/services/cli-backend/http-client.ts
+++ b/packages/kilo-vscode/src/services/cli-backend/http-client.ts
@@ -214,7 +214,7 @@ export class HttpClient {
     sessionId: string,
     parts: Array<{ type: "text"; text: string } | { type: "file"; mime: string; url: string }>,
     directory: string,
-    options?: { providerID?: string; modelID?: string; agent?: string },
+    options?: { providerID?: string; modelID?: string; agent?: string; variant?: string },
   ): Promise<void> {
     const body: Record<string, unknown> = { parts }
     if (options?.providerID && options?.modelID) {
@@ -224,6 +224,9 @@ export class HttpClient {
     if (options?.agent) {
       body.agent = options.agent
     }
+    if (options?.variant) {
+      body.variant = options.variant
+    }
 
     await this.request<void>("POST", `/session/${sessionId}/message`, body, { directory, allowEmpty: true })
   }
diff --git a/packages/kilo-vscode/src/services/cli-backend/types.ts b/packages/kilo-vscode/src/services/cli-backend/types.ts
index 461082255..bf143c714 100644
--- a/packages/kilo-vscode/src/services/cli-backend/types.ts
+++ b/packages/kilo-vscode/src/services/cli-backend/types.ts
@@ -139,6 +139,8 @@ export interface ProviderModel {
   latest?: boolean
   // Actual shape returned by the server (Provider.Model)
   limit?: { context: number; input?: number; output: number }
+  variants?: Record<string, Record<string, unknown>>
+  capabilities?: { reasoning: boolean }
 }
 
 // Provider definition
diff --git a/packages/kilo-vscode/webview-ui/src/components/chat/PromptInput.tsx b/packages/kilo-vscode/webview-ui/src/components/chat/PromptInput.tsx
index 64c26abaa..6f089960a 100644
--- a/packages/kilo-vscode/webview-ui/src/components/chat/PromptInput.tsx
+++ b/packages/kilo-vscode/webview-ui/src/components/chat/PromptInput.tsx
@@ -314,6 +314,18 @@ export const PromptInput: Component = () => {
         <div class="prompt-input-hint-selectors">
           <ModeSwitcher />
           <ModelSelector />
+          <Show when={session.variantList().length > 0}>
+            <Tooltip value={language.t("command.model.variant.cycle")} placement="top">
+              <Button
+                variant="ghost"
+                size="small"
+                onClick={() => session.cycleVariant()}
+                aria-label={language.t("command.model.variant.cycle")}
+              >
+                {session.currentVariant() ?? language.t("common.default")}
+              </Button>
+            </Tooltip>
+          </Show>
         </div>
         <div class="prompt-input-hint-actions">
           <Show
diff --git a/packages/kilo-vscode/webview-ui/src/context/session.tsx b/packages/kilo-vscode/webview-ui/src/context/session.tsx
index 2f1b4f836..58457b92a 100644
--- a/packages/kilo-vscode/webview-ui/src/context/session.tsx
+++ b/packages/kilo-vscode/webview-ui/src/context/session.tsx
@@ -48,6 +48,7 @@ interface SessionStore {
   todos: Record<string, TodoItem[]> // sessionID -> todos
   modelSelections: Record<string, ModelSelection> // sessionID -> model
   agentSelections: Record<string, string> // sessionID -> agent name
+  variantSelections: Record<string, string | undefined> // "providerID/modelID" -> variant name
 }
 
 interface SessionContextValue {
@@ -105,6 +106,11 @@ interface SessionContextValue {
   setSessionModel: (sessionID: string, providerID: string, modelID: string) => void
   setSessionAgent: (sessionID: string, name: string) => void
 
+  // Thinking variant for the selected model
+  variantList: () => string[]
+  currentVariant: () => string | undefined
+  cycleVariant: () => void
+
   // Actions
   sendMessage: (text: string, providerID?: string, modelID?: string, files?: FileAttachment[]) => void
   abort: () => void
@@ -177,6 +183,7 @@ export const SessionProvider: ParentComponent = (props) => {
     todos: {},
     modelSelections: {},
     agentSelections: {},
+    variantSelections: {},
   })
 
   // Keep pending selection in sync with provider default until the user
@@ -268,6 +275,56 @@ export const SessionProvider: ParentComponent = (props) => {
     clearInterval(agentRetryTimer)
   })
 
+  // Variant (thinking effort) selection — keyed by "providerID/modelID"
+  const variantKey = (sel: ModelSelection) => `${sel.providerID}/${sel.modelID}`
+
+  const variantList = () => {
+    const sel = selected()
+    if (!sel) return []
+    const model = provider.findModel(sel)
+    if (!model?.variants) return []
+    return Object.keys(model.variants)
+  }
+
+  const currentVariant = () => {
+    const sel = selected()
+    if (!sel) return undefined
+    const key = variantKey(sel)
+    const stored = store.variantSelections[key]
+    const list = variantList()
+    if (stored && list.includes(stored)) return stored
+    return undefined
+  }
+
+  const cycleVariant = () => {
+    const sel = selected()
+    if (!sel) return
+    const list = variantList()
+    if (list.length === 0) return
+    const key = variantKey(sel)
+    const current = store.variantSelections[key]
+    const next = (() => {
+      if (!current || !list.includes(current)) return list[0]
+      const idx = list.indexOf(current)
+      if (idx === list.length - 1) return undefined
+      return list[idx + 1]
+    })()
+    setStore("variantSelections", key, next)
+    vscode.postMessage({ type: "persistVariant", key, value: next })
+  }
+
+  // Load persisted variants from extension globalState
+  const unsubVariants = vscode.onMessage((message: ExtensionMessage) => {
+    if (message.type !== "variantsLoaded") return
+    for (const [k, v] of Object.entries(message.variants)) {
+      setStore("variantSelections", k, v)
+    }
+  })
+
+  vscode.postMessage({ type: "requestVariants" })
+
+  onCleanup(unsubVariants)
+
   // Handle messages from extension
   onMount(() => {
     const unsubscribe = vscode.onMessage((message: ExtensionMessage) => {
@@ -631,6 +688,7 @@ export const SessionProvider: ParentComponent = (props) => {
       providerID,
       modelID,
       agent,
+      variant: currentVariant(),
       files,
     })
   }
@@ -866,6 +924,9 @@ export const SessionProvider: ParentComponent = (props) => {
     },
     allMessages,
     allParts,
+    variantList,
+    currentVariant,
+    cycleVariant,
     sendMessage,
     abort,
     compact,
diff --git a/packages/kilo-vscode/webview-ui/src/types/messages.ts b/packages/kilo-vscode/webview-ui/src/types/messages.ts
index 8c9f7b003..06320f478 100644
--- a/packages/kilo-vscode/webview-ui/src/types/messages.ts
+++ b/packages/kilo-vscode/webview-ui/src/types/messages.ts
@@ -215,6 +215,8 @@ export interface ProviderModel {
   latest?: boolean
   // Actual shape returned by the server (Provider.Model)
   limit?: { context: number; input?: number; output: number }
+  variants?: Record<string, Record<string, unknown>>
+  capabilities?: { reasoning: boolean }
 }
 
 export interface Provider {
@@ -607,6 +609,12 @@ export interface AgentManagerMultiVersionProgressMessage {
   groupId?: string
 }
 
+// Stored variant selections loaded from extension globalState (extension → webview)
+export interface VariantsLoadedMessage {
+  type: "variantsLoaded"
+  variants: Record<string, string | undefined>
+}
+
 // Request webview to send initial prompt to a newly created session (extension → webview)
 export interface AgentManagerSendInitialMessage {
   type: "agentManager.sendInitialMessage"
@@ -663,6 +671,7 @@ export type ExtensionMessage =
   | AgentManagerSendInitialMessage
   | SetChatBoxMessage
   | TriggerTaskMessage
+  | VariantsLoadedMessage
 
 // ============================================
 // Messages FROM webview TO extension
@@ -680,6 +689,7 @@ export interface SendMessageRequest {
   providerID?: string
   modelID?: string
   agent?: string
+  variant?: string
   files?: FileAttachment[]
 }
 
@@ -947,6 +957,18 @@ export interface SetSessionsCollapsedRequest {
   collapsed: boolean
 }
 
+// Variant persistence (webview → extension)
+export interface PersistVariantRequest {
+  type: "persistVariant"
+  key: string
+  value: string | undefined
+}
+
+// Request stored variants from extension (webview → extension)
+export interface RequestVariantsMessage {
+  type: "requestVariants"
+}
+
 export type WebviewMessage =
   | SendMessageRequest
   | AbortRequest
@@ -999,6 +1021,8 @@ export type WebviewMessage =
   | CreateMultiVersionRequest
   | SetTabOrderRequest
   | SetSessionsCollapsedRequest
+  | PersistVariantRequest
+  | RequestVariantsMessage
 
 // ============================================
 // VS Code API type