diff --git a/frontend/src/api/l1.ts b/frontend/src/api/l1.ts
index 512cc0f1..482d089a 100644
--- a/frontend/src/api/l1.ts
+++ b/frontend/src/api/l1.ts
@@ -1,7 +1,10 @@
 import { apiClient } from './client'
 import type {
   IntakeRequest,
-  IntakeResponse,
+  IntakeResult,
+  L1Categories,
+  NextNodeRequest,
+  NextNodeResult,
   QueueRow,
   WalkSession,
   AdhocNote,
@@ -9,7 +12,23 @@ import type {
 
 export const l1Api = {
   intake: (body: IntakeRequest) =>
-    apiClient.post<IntakeResponse>('/l1/intake', body).then(r => r.data),
+    apiClient.post<IntakeResult>('/l1/intake', body).then(r => r.data),
+
+  nextNode: (sessionId: string, body: NextNodeRequest) =>
+    apiClient
+      .post<NextNodeResult>(`/l1/sessions/${sessionId}/next-node`, body)
+      .then(r => r.data),
+
+  escalations: () =>
+    apiClient.get<WalkSession[]>('/l1/escalations').then(r => r.data),
+
+  getCategories: () =>
+    apiClient.get<L1Categories>('/accounts/me/l1-categories').then(r => r.data),
+
+  setCategories: (enabled: string[]) =>
+    apiClient
+      .patch<L1Categories>('/accounts/me/l1-categories', { enabled })
+      .then(r => r.data),
 
   queue: (statusFilter?: string) =>
     apiClient.get<QueueRow[]>('/l1/queue', {
diff --git a/frontend/src/types/l1.ts b/frontend/src/types/l1.ts
index 95c499b5..ea74a577 100644
--- a/frontend/src/types/l1.ts
+++ b/frontend/src/types/l1.ts
@@ -1,4 +1,4 @@
-export type SessionKind = 'flow' | 'proposal' | 'adhoc'
+export type SessionKind = 'flow' | 'proposal' | 'adhoc' | 'ai_build'
 export type SessionStatus = 'active' | 'resolved' | 'escalated' | 'abandoned'
 export type TicketKind = 'psa' | 'internal'
 
@@ -42,11 +42,53 @@ export interface IntakeRequest {
   customer_name?: string
   customer_contact?: string
   flow_id?: string
+  force_build?: boolean
 }
 
-export interface IntakeResponse {
-  session_id: string
-  session_kind: SessionKind
-  ticket_id: string
-  ticket_kind: TicketKind
+export type IntakeOutcome = 'matched' | 'suggest' | 'out_of_scope' | 'build'
+
+export interface NearMiss {
+  flow_id: string
+  flow_name: string
+  score: number
+}
+
+/** Phase 2A intake response — `outcome` drives the frontend dispatch.
+ *  Session fields are present only for `matched` / `build`. */
+export interface IntakeResult {
+  outcome: IntakeOutcome
+  session_id?: string
+  session_kind?: SessionKind
+  ticket_id?: string
+  ticket_kind?: TicketKind
+  flow_id?: string        // for 'matched'
+  near_miss?: NearMiss     // for 'suggest'
+  category?: string        // for 'out_of_scope'
+}
+
+/** A single node of an AI-built decision tree, returned by /next-node. */
+export type TreeNode =
+  | { node_type: 'question'; id: string; text: string }
+  | { node_type: 'instruction'; id: string; text: string }
+  | { node_type: 'resolved'; id: string; text: string }
+  | { node_type: 'escalate'; id: string; reason_category?: string; text: string }
+  | { node_type: 'needs_review'; id: string; text: string }
+
+export interface NextNodeRequest {
+  node_id?: string
+  node_text?: string       // rendered text of the node being answered
+  answer?: 'yes' | 'no'
+  acknowledged?: boolean
+  note?: string
+}
+
+export interface NextNodeResult {
+  node: TreeNode
+  session_status: string
+}
+
+export interface L1Categories {
+  enabled: string[]
+  available: string[]
+  hard_floor: string[]
 }