feat(vscode): add task header with cost, context usage, and compact button

Add a sticky TaskHeader component above the chat messages showing session
title, accumulated cost, context token usage, and a button to trigger
context compaction (summarization).

Wire cost and token data through the message pipeline (SSE message.updated
events and initial message load) so the webview can compute session totals.

Closes #166

packages/kilo-vscode/src/KiloProvider.ts

@@ -182,6 +182,9 @@ export class KiloProvider implements vscode.WebviewViewProvider {
         case "requestProviders":
           await this.fetchAndSendProviders()
           break
+        case "compact":
+          await this.handleCompact(message.sessionID, message.providerID, message.modelID)
+          break
       }
     })
   }
@@ -332,13 +335,15 @@ export class KiloProvider implements vscode.WebviewViewProvider {
       const workspaceDir = this.getWorkspaceDirectory()
       const messagesData = await this.httpClient.getMessages(sessionID, workspaceDir)
 
-      // Convert to webview format
+      // Convert to webview format, including cost/tokens for assistant messages
       const messages = messagesData.map((m) => ({
         id: m.info.id,
         sessionID: m.info.sessionID,
         role: m.info.role,
         parts: m.parts,
         createdAt: new Date(m.info.time.created).toISOString(),
+        cost: m.info.cost,
+        tokens: m.info.tokens,
       }))
 
       for (const message of messages) {
@@ -504,6 +509,32 @@ export class KiloProvider implements vscode.WebviewViewProvider {
     }
   }
 
+  /**
+   * Handle compact (context summarization) request from the webview.
+   */
+  private async handleCompact(sessionID?: string, providerID?: string, modelID?: string): Promise<void> {
+    if (!this.httpClient) {
+      return
+    }
+
+    const target = sessionID || this.currentSession?.id
+    if (!target) {
+      console.error("[Kilo New] KiloProvider: No sessionID for compact")
+      return
+    }
+
+    try {
+      const workspaceDir = this.getWorkspaceDirectory()
+      await this.httpClient.summarize(target, providerID || "kilo", modelID || "kilo/auto", workspaceDir)
+    } catch (error) {
+      console.error("[Kilo New] KiloProvider: Failed to compact session:", error)
+      this.postMessage({
+        type: "error",
+        message: error instanceof Error ? error.message : "Failed to compact session",
+      })
+    }
+  }
+
   /**
    * Handle permission response from the webview.
    */
@@ -672,7 +703,7 @@ export class KiloProvider implements vscode.WebviewViewProvider {
       }
 
       case "message.updated":
-        // Message info updated
+        // Message info updated — forward cost/tokens for assistant messages
         this.postMessage({
           type: "messageCreated",
           message: {
@@ -680,6 +711,8 @@ export class KiloProvider implements vscode.WebviewViewProvider {
             sessionID: event.properties.info.sessionID,
             role: event.properties.info.role,
             createdAt: new Date(event.properties.info.time.created).toISOString(),
+            cost: event.properties.info.cost,
+            tokens: event.properties.info.tokens,
           },
         })
         break

packages/kilo-vscode/src/services/cli-backend/http-client.ts

@@ -192,6 +192,18 @@ export class HttpClient {
     return true
   }
 
+  /**
+   * Trigger context compaction (summarization) for a session.
+   */
+  async summarize(sessionId: string, providerID: string, modelID: string, directory: string): Promise<boolean> {
+    return this.request<boolean>(
+      "POST",
+      `/session/${sessionId}/summarize`,
+      { providerID, modelID, auto: false },
+      { directory, allowEmpty: true },
+    )
+  }
+
   // ============================================
   // Permission Methods
   // ============================================

packages/kilo-vscode/src/services/cli-backend/index.ts

@@ -6,6 +6,7 @@ export type {
   SessionStatusInfo,
   MessageInfo,
   MessagePart,
+  TokenUsage,
   ToolState,
   PermissionRequest,
   SSEEvent,

packages/kilo-vscode/src/services/cli-backend/types.ts

@@ -18,6 +18,14 @@ export type SessionStatusInfo =
   | { type: "retry"; attempt: number; message: string; next: number }
   | { type: "busy" }
 
+// Token usage shape returned by the server on assistant messages
+export interface TokenUsage {
+  input: number
+  output: number
+  reasoning: number
+  cache: { read: number; write: number }
+}
+
 // Message types from MessageV2
 export interface MessageInfo {
   id: string
@@ -27,6 +35,9 @@ export interface MessageInfo {
     created: number
     completed?: number
   }
+  // Present on assistant messages
+  cost?: number
+  tokens?: TokenUsage
 }
 
 // Part types - simplified for UI display

packages/kilo-vscode/webview-ui/src/components/chat/ChatView.tsx

@@ -4,6 +4,7 @@
  */
 
 import { Component } from "solid-js"
+import { TaskHeader } from "./TaskHeader"
 import { MessageList } from "./MessageList"
 import { PromptInput } from "./PromptInput"
 import { PermissionDialog } from "./PermissionDialog"
@@ -11,6 +12,7 @@ import { PermissionDialog } from "./PermissionDialog"
 export const ChatView: Component = () => {
   return (
     <div class="chat-view">
+      <TaskHeader />
       <div class="chat-messages">
         <MessageList />
       </div>

packages/kilo-vscode/webview-ui/src/components/chat/TaskHeader.tsx

@@ -0,0 +1,75 @@
+/**
+ * TaskHeader component
+ * Sticky header above the chat messages showing session title,
+ * cost, context usage, and a compact button.
+ */
+
+import { Component, Show, createMemo } from "solid-js"
+import { IconButton } from "@kilocode/kilo-ui/icon-button"
+import { Tooltip } from "@kilocode/kilo-ui/tooltip"
+import { useSession } from "../../context/session"
+
+export const TaskHeader: Component = () => {
+  const session = useSession()
+
+  const title = createMemo(() => session.currentSession()?.title)
+  const hasMessages = createMemo(() => session.messages().length > 0)
+  const visible = createMemo(() => !!(title() && hasMessages()))
+  const busy = createMemo(() => session.status() === "busy")
+
+  const cost = createMemo(() => {
+    const total = session.totalCost()
+    if (total === 0) return undefined
+    return new Intl.NumberFormat("en-US", {
+      style: "currency",
+      currency: "USD",
+    }).format(total)
+  })
+
+  const context = createMemo(() => {
+    const usage = session.contextUsage()
+    if (!usage) return undefined
+    const tokens = usage.tokens.toLocaleString("en-US")
+    const pct = usage.percentage !== null ? `${usage.percentage}%` : undefined
+    return { tokens, pct }
+  })
+
+  return (
+    <Show when={visible()}>
+      <div class="task-header">
+        <div class="task-header-title" title={title()}>
+          {title()}
+        </div>
+        <div class="task-header-stats">
+          <Show when={cost()}>
+            {(c) => (
+              <Tooltip value="Session cost" placement="bottom">
+                <span class="task-header-stat">{c()}</span>
+              </Tooltip>
+            )}
+          </Show>
+          <Show when={context()}>
+            {(ctx) => (
+              <Tooltip
+                value={ctx().pct ? `${ctx().tokens} tokens (${ctx().pct} of context)` : `${ctx().tokens} tokens`}
+                placement="bottom"
+              >
+                <span class="task-header-stat">{ctx().pct ?? ctx().tokens}</span>
+              </Tooltip>
+            )}
+          </Show>
+          <Tooltip value="Compact session" placement="bottom">
+            <IconButton
+              icon="collapse"
+              size="small"
+              variant="ghost"
+              disabled={busy() || !hasMessages()}
+              onClick={() => session.compact()}
+              aria-label="Compact session"
+            />
+          </Tooltip>
+        </div>
+      </div>
+    </Show>
+  )
+}

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

@@ -29,6 +29,7 @@ import type {
   PermissionRequest,
   TodoItem,
   ModelSelection,
+  ContextUsage,
   ExtensionMessage,
 } from "../types/messages"
 
@@ -69,9 +70,14 @@ interface SessionContextValue {
   selected: Accessor<ModelSelection | null>
   selectModel: (providerID: string, modelID: string) => void
 
+  // Cost and context usage for the current session
+  totalCost: Accessor<number>
+  contextUsage: Accessor<ContextUsage | undefined>
+
   // Actions
   sendMessage: (text: string, providerID?: string, modelID?: string) => void
   abort: () => void
+  compact: () => void
   respondToPermission: (permissionId: string, response: "once" | "always" | "reject") => void
   createSession: () => void
   loadSessions: () => void
@@ -335,6 +341,22 @@ export const SessionProvider: ParentComponent = (props) => {
     })
   }
 
+  function compact() {
+    const sessionID = currentSessionID()
+    if (!sessionID) {
+      console.warn("[Kilo New] Cannot compact: no current session")
+      return
+    }
+
+    const sel = selected()
+    vscode.postMessage({
+      type: "compact",
+      sessionID,
+      providerID: sel?.providerID,
+      modelID: sel?.modelID,
+    })
+  }
+
   function respondToPermission(permissionId: string, response: "once" | "always" | "reject") {
     // Resolve sessionID from the stored permission request
     const permission = permissions().find((p) => p.id === permissionId)
@@ -405,6 +427,27 @@ export const SessionProvider: ParentComponent = (props) => {
     Object.values(store.sessions).sort((a, b) => new Date(b.updatedAt).getTime() - new Date(a.updatedAt).getTime()),
   )
 
+  // Total cost across all assistant messages in the current session
+  const totalCost = createMemo(() => {
+    return messages().reduce((sum, m) => sum + (m.role === "assistant" ? (m.cost ?? 0) : 0), 0)
+  })
+
+  // Context usage from the last assistant message that has token data
+  const contextUsage = createMemo<ContextUsage | undefined>(() => {
+    const msgs = messages()
+    for (let i = msgs.length - 1; i >= 0; i--) {
+      const m = msgs[i]
+      if (m.role !== "assistant" || !m.tokens) continue
+      const total = m.tokens.input + m.tokens.output + m.tokens.reasoning + m.tokens.cache.read + m.tokens.cache.write
+      if (total === 0) continue
+      const sel = selected()
+      const model = sel ? provider.findModel(sel) : undefined
+      const percentage = model?.contextLength ? Math.round((total / model.contextLength) * 100) : null
+      return { tokens: total, percentage }
+    }
+    return undefined
+  })
+
   const value: SessionContextValue = {
     currentSessionID,
     currentSession,
@@ -417,8 +460,11 @@ export const SessionProvider: ParentComponent = (props) => {
     permissions,
     selected,
     selectModel,
+    totalCost,
+    contextUsage,
     sendMessage,
     abort,
+    compact,
     respondToPermission,
     createSession,
     loadSessions,

packages/kilo-vscode/webview-ui/src/styles/chat.css

@@ -20,6 +20,44 @@
   min-height: 0;
 }
 
+/* ============================================
+   Task Header
+   ============================================ */
+
+.task-header {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 6px 12px;
+  background: var(--vscode-sideBar-background);
+  border-bottom: 1px solid var(--vscode-panel-border);
+  flex-shrink: 0;
+  min-height: 32px;
+}
+
+.task-header-title {
+  flex: 1;
+  font-size: 12px;
+  font-weight: 600;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  color: var(--vscode-foreground);
+}
+
+.task-header-stats {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  flex-shrink: 0;
+}
+
+.task-header-stat {
+  font-size: 11px;
+  color: var(--vscode-descriptionForeground);
+  white-space: nowrap;
+}
+
 .chat-input {
   flex-shrink: 0;
   border-top: 1px solid var(--vscode-panel-border);

packages/kilo-vscode/webview-ui/src/types/messages.ts

@@ -64,6 +64,20 @@ export interface PartDelta {
   textDelta?: string
 }
 
+// Token usage for assistant messages
+export interface TokenUsage {
+  input: number
+  output: number
+  reasoning: number
+  cache: { read: number; write: number }
+}
+
+// Context usage derived from the last assistant message's tokens
+export interface ContextUsage {
+  tokens: number
+  percentage: number | null
+}
+
 // Message structure (simplified for webview)
 export interface Message {
   id: string
@@ -72,6 +86,8 @@ export interface Message {
   content?: string
   parts?: Part[]
   createdAt: string
+  cost?: number
+  tokens?: TokenUsage
 }
 
 // Session info (simplified for webview)
@@ -345,6 +361,13 @@ export interface RequestProvidersMessage {
   type: "requestProviders"
 }
 
+export interface CompactRequest {
+  type: "compact"
+  sessionID: string
+  providerID?: string
+  modelID?: string
+}
+
 export type WebviewMessage =
   | SendMessageRequest
   | AbortRequest
@@ -359,6 +382,7 @@ export type WebviewMessage =
   | CancelLoginRequest
   | WebviewReadyRequest
   | RequestProvidersMessage
+  | CompactRequest
 
 // ============================================
 // VS Code API type