diff --git a/frontend/src/types/ai-session.ts b/frontend/src/types/ai-session.ts
index 94bc6d08..0a684871 100644
--- a/frontend/src/types/ai-session.ts
+++ b/frontend/src/types/ai-session.ts
@@ -195,6 +195,8 @@ export interface AISessionDetail extends AISessionSummary {
   ticket_data: Record<string, unknown> | null
   steps: AISessionStepResponse[]
   conversation_messages: Array<{ role: string; content: string }>
+  is_branching: boolean
+  active_branch_id: string | null
 }
 
 export interface AISessionSearchResult {
diff --git a/frontend/src/types/branching.ts b/frontend/src/types/branching.ts
new file mode 100644
index 00000000..f01565a1
--- /dev/null
+++ b/frontend/src/types/branching.ts
@@ -0,0 +1,160 @@
+// ── Branches ──
+
+export interface BranchResponse {
+  id: string
+  session_id: string
+  parent_branch_id: string | null
+  fork_point_step_id: string | null
+  branch_order: number
+  label: string
+  status: 'active' | 'dead_end' | 'solved' | 'untried' | 'revived'
+  status_reason: string | null
+  status_changed_at: string | null
+  context_summary: {
+    tried: string[]
+    concluded: string
+    artifacts: string[]
+  } | null
+  evidence_from_branch_id: string | null
+  evidence_description: string | null
+  step_count: number
+  created_at: string
+  updated_at: string
+}
+
+export interface BranchTreeResponse {
+  branches: BranchResponse[]
+  active_branch_id: string | null
+}
+
+export interface ForkOption {
+  label: string
+  description: string
+}
+
+export interface ForkCreateRequest {
+  fork_reason: string
+  options: ForkOption[]
+}
+
+export interface ForkPointResponse {
+  id: string
+  session_id: string
+  parent_branch_id: string
+  trigger_step_id: string | null
+  fork_reason: string
+  options: Array<{
+    label: string
+    description: string
+    branch_id: string
+    status: string
+  }>
+  created_at: string
+}
+
+export interface BranchSwitchResponse {
+  active_branch_id: string
+  branch: BranchResponse
+  conversation_messages: Array<{ role: string; content: string }>
+}
+
+export interface ReviveRequest {
+  evidence_from_branch_id: string
+  evidence_description: string
+}
+
+export interface BranchMessageRequest {
+  message: string
+  upload_ids?: string[]
+}
+
+export interface BranchMessageResponse {
+  content: string
+  branch_id: string
+  step_id: string | null
+}
+
+// ── Handoffs ──
+
+export interface HandoffCreateRequest {
+  intent: 'park' | 'escalate'
+  engineer_notes?: string
+  priority?: 'normal' | 'elevated'
+}
+
+export interface HandoffResponse {
+  id: string
+  session_id: string
+  handed_off_by: string
+  intent: 'park' | 'escalate'
+  source_branch_id: string | null
+  snapshot: Record<string, unknown>
+  ai_assessment: string | null
+  ai_assessment_data: {
+    likely_cause: string
+    suggested_steps: string[]
+    confidence: number
+  } | null
+  artifacts: Array<{
+    name: string
+    type: string
+    reference: string
+  }> | null
+  engineer_notes: string | null
+  priority: 'normal' | 'elevated'
+  claimed_by: string | null
+  claimed_at: string | null
+  psa_note_pushed: boolean
+  notification_sent: boolean
+  created_at: string
+}
+
+export interface QueueItemResponse {
+  handoff_id: string
+  session_id: string
+  intent: 'park' | 'escalate'
+  problem_summary: string | null
+  problem_domain: string | null
+  priority: 'normal' | 'elevated'
+  handed_off_by_name: string | null
+  engineer_notes: string | null
+  branch_count: number
+  created_at: string
+  claimed_by: string | null
+  claimed_at: string | null
+}
+
+// ── Resolution Outputs ──
+
+export type ResolutionOutputType = 'psa_ticket_notes' | 'knowledge_base' | 'client_summary'
+export type ResolutionOutputStatus = 'draft' | 'approved' | 'pushed' | 'rejected'
+
+export interface ResolutionOutputResponse {
+  id: string
+  session_id: string
+  output_type: ResolutionOutputType
+  generated_content: string
+  structured_data: Record<string, unknown> | null
+  edited_content: string | null
+  status: ResolutionOutputStatus
+  pushed_to: string | null
+  pushed_at: string | null
+  pushed_reference: string | null
+  generated_by_model: string
+  created_at: string
+  updated_at: string
+}
+
+export interface AllResolutionOutputsResponse {
+  outputs: ResolutionOutputResponse[]
+}
+
+export interface ResolutionOutputEditRequest {
+  edited_content: string
+}
+
+export type PushDestination = 'psa' | 'kb_library' | 'clipboard' | 'email'
+
+export interface ResolutionOutputPushRequest {
+  destination: PushDestination
+}
diff --git a/frontend/src/types/index.ts b/frontend/src/types/index.ts
index 7fffdeb6..b44ccc84 100644
--- a/frontend/src/types/index.ts
+++ b/frontend/src/types/index.ts
@@ -13,6 +13,7 @@ export * from './analytics'
 export * from './copilot'
 export type { ChatListItem, RetentionSettings, ConclusionOutcome } from './assistant-chat'
 export * from './ai-session'
+export * from './branching'
 export * from './flow-proposal'
 export * from './flowpilot-analytics'
 export * from './upload'