diff --git a/web/src/api/acp.ts b/web/src/api/acp.ts
index 25d6b93..4039caa 100644
--- a/web/src/api/acp.ts
+++ b/web/src/api/acp.ts
@@ -47,6 +47,54 @@ export interface UpdateAgentKindReq {
   enabled?: boolean
 }
 
+// AcpSession mirrors the backend session DTO returned by /api/v1/acp/sessions.
+export interface AcpSession {
+  id: string
+  workspace_id: string
+  project_id: string
+  agent_kind_id: string
+  user_id: string
+  issue_id: string | null
+  requirement_id: string | null
+  agent_session_id: string | null
+  branch: string
+  cwd_path: string
+  is_main_worktree: boolean
+  status: 'starting' | 'running' | 'crashed' | 'exited'
+  pid: number | null
+  exit_code: number | null
+  last_error: string | null
+  started_at: string
+  ended_at: string | null
+}
+
+export interface CreateSessionReq {
+  workspace_id: string
+  agent_kind_id: string
+  branch?: string
+  issue_number?: number
+  requirement_number?: number
+  initial_prompt?: string
+}
+
+// AcpEvent is one frame from the session event stream (history REST + WS push).
+export interface AcpEvent {
+  id: number
+  direction: 'in' | 'out'
+  kind:
+    | 'request'
+    | 'response'
+    | 'notification'
+    | 'error'
+    | 'state'
+    | 'session_terminated'
+    | 'slow_consumer_disconnect'
+    | 'client_error'
+  method?: string
+  payload: unknown
+  truncated: boolean
+}
+
 const enc = (v: string) => encodeURIComponent(v)
 
 export const acpApi = {
@@ -62,4 +110,30 @@ export const acpApi = {
     remove: (id: string) =>
       request<void>(`/api/v1/acp/agent-kinds/${enc(id)}`, { method: 'DELETE' }),
   },
+  sessions: {
+    list: (all?: boolean) =>
+      request<AcpSession[]>('/api/v1/acp/sessions' + (all ? '?all=true' : '')),
+    get: (id: string) =>
+      request<AcpSession>(`/api/v1/acp/sessions/${enc(id)}`),
+    create: (req: CreateSessionReq) =>
+      request<AcpSession>('/api/v1/acp/sessions', { method: 'POST', body: req }),
+    terminate: (id: string) =>
+      request<void>(`/api/v1/acp/sessions/${enc(id)}`, { method: 'DELETE' }),
+    events: (id: string, since: number) =>
+      request<AcpEvent[]>(`/api/v1/acp/sessions/${enc(id)}/events?since=${since}`),
+  },
+}
+
+// openSessionWS opens a native WebSocket to /sessions/{id}/ws.
+//
+// Auth: browser WebSocket cannot send custom headers, so the token is sent
+// via the ?token= query parameter. The backend auth middleware accepts it
+// as a fallback to Authorization. Keep token lifetimes short.
+export function openSessionWS(sessionId: string, since: number, token: string): WebSocket {
+  const proto = window.location.protocol === 'https:' ? 'wss' : 'ws'
+  const host = window.location.host
+  const url =
+    `${proto}://${host}/api/v1/acp/sessions/${enc(sessionId)}` +
+    `/ws?since=${since}&token=${enc(token)}`
+  return new WebSocket(url)
 }