diff --git a/web/src/lib/api/client/app/leadsync/createSource.ts b/web/src/lib/api/client/app/leadsync/createSource.ts
new file mode 100644
index 000000000..9e1b274f8
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/createSource.ts
@@ -0,0 +1,19 @@
+import type {
+    CreateLeadSyncSource,
+    LeadSyncSource,
+} from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// Saves a new on-demand source. The backend validates the connection is the
+// org's google_sheets connection, dedup is valid, and column_mapping maps a
+// column to 'email'.
+export default async function createSource(
+    input: CreateLeadSyncSource,
+): Promise<LeadSyncSource> {
+    return await Request<LeadSyncSource>({
+        method: "POST",
+        url: "/lead-sync/sources",
+        data: input,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/deleteSource.ts b/web/src/lib/api/client/app/leadsync/deleteSource.ts
new file mode 100644
index 000000000..d4e576837
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/deleteSource.ts
@@ -0,0 +1,10 @@
+import Request from "../../Request";
+
+// Deletes a saved source (org-scoped). Backend returns 204 No Content.
+export default async function deleteSource(id: string): Promise<void> {
+    await Request<void>({
+        method: "DELETE",
+        url: `/lead-sync/sources/${id}`,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/getGoogleConnection.ts b/web/src/lib/api/client/app/leadsync/getGoogleConnection.ts
new file mode 100644
index 000000000..609af68d5
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/getGoogleConnection.ts
@@ -0,0 +1,12 @@
+import type { LeadSyncConnection } from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// Reports whether the org has a connected (hidden) google_sheets OAuth
+// connection usable for lead-sync. Drives "Connect Google" vs the sheet picker.
+export default async function getGoogleConnection(): Promise<LeadSyncConnection> {
+    return await Request<LeadSyncConnection>({
+        method: "GET",
+        url: "/lead-sync/google/connection",
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/getSource.ts b/web/src/lib/api/client/app/leadsync/getSource.ts
new file mode 100644
index 000000000..3006ffb4f
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/getSource.ts
@@ -0,0 +1,11 @@
+import type { LeadSyncSource } from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// Returns one saved source (org-scoped).
+export default async function getSource(id: string): Promise<LeadSyncSource> {
+    return await Request<LeadSyncSource>({
+        method: "GET",
+        url: `/lead-sync/sources/${id}`,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/getSpreadsheet.ts b/web/src/lib/api/client/app/leadsync/getSpreadsheet.ts
new file mode 100644
index 000000000..b2d3fdab2
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/getSpreadsheet.ts
@@ -0,0 +1,16 @@
+import type { SheetMeta } from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// Returns a spreadsheet's title + tabs (read via the connection's refreshed
+// Google token) so the UI can render a tab picker.
+export default async function getSpreadsheet(input: {
+    connection_id: string;
+    sheet_id: string;
+}): Promise<SheetMeta> {
+    return await Request<SheetMeta>({
+        method: "POST",
+        url: "/lead-sync/google/spreadsheet",
+        data: input,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/listSources.ts b/web/src/lib/api/client/app/leadsync/listSources.ts
new file mode 100644
index 000000000..58ce00f6f
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/listSources.ts
@@ -0,0 +1,14 @@
+import type { LeadSyncSource } from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// Lists this org's saved sync sources, optionally filtered to one campaign
+// (powers both the global Contacts > Sync sources area and the per-campaign
+// "Connect a Google Sheet" list).
+export default async function listSources(campaignId?: string): Promise<{ data: LeadSyncSource[] }> {
+    return await Request<{ data: LeadSyncSource[] }>({
+        method: "GET",
+        url: "/lead-sync/sources",
+        params: campaignId ? { campaign_id: campaignId } : undefined,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/previewSheet.ts b/web/src/lib/api/client/app/leadsync/previewSheet.ts
new file mode 100644
index 000000000..3e11ff92b
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/previewSheet.ts
@@ -0,0 +1,18 @@
+import type { ImportPreview } from "@/lib/api/client/app/contacts/importContacts";
+import Request from "../../Request";
+
+// Reads the first ~21 rows of a tab and returns the exact contacts
+// ImportPreview JSON shape, so the frontend reuses its contact-import column
+// mapper verbatim.
+export default async function previewSheet(input: {
+    connection_id: string;
+    sheet_id: string;
+    tab_title: string;
+}): Promise<ImportPreview> {
+    return await Request<ImportPreview>({
+        method: "POST",
+        url: "/lead-sync/google/preview",
+        data: input,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/syncSource.ts b/web/src/lib/api/client/app/leadsync/syncSource.ts
new file mode 100644
index 000000000..9788571cd
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/syncSource.ts
@@ -0,0 +1,13 @@
+import type { LeadSyncResult } from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// "Sync now": reads the full sheet tab, encodes rows as CSV in memory, and runs
+// the existing contact ImportCommit (upsert by email, attach categories +
+// target campaign). Naturally idempotent (email upsert), so no Idempotency-Key.
+export default async function syncSource(id: string): Promise<LeadSyncResult> {
+    return await Request<LeadSyncResult>({
+        method: "POST",
+        url: `/lead-sync/sources/${id}/sync`,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/client/app/leadsync/updateSource.ts b/web/src/lib/api/client/app/leadsync/updateSource.ts
new file mode 100644
index 000000000..3e1e42e95
--- /dev/null
+++ b/web/src/lib/api/client/app/leadsync/updateSource.ts
@@ -0,0 +1,19 @@
+import type {
+    LeadSyncSource,
+    UpdateLeadSyncSource,
+} from "@/lib/api/models/app/leadsync/LeadSync";
+import Request from "../../Request";
+
+// Edits a saved source; omitted fields are left unchanged. clear_campaign:true
+// detaches the target campaign.
+export default async function updateSource(
+    id: string,
+    input: UpdateLeadSyncSource,
+): Promise<LeadSyncSource> {
+    return await Request<LeadSyncSource>({
+        method: "PATCH",
+        url: `/lead-sync/sources/${id}`,
+        data: input,
+        authorization: true,
+    });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useCreateLeadSyncSource.ts b/web/src/lib/api/hooks/app/leadsync/useCreateLeadSyncSource.ts
new file mode 100644
index 000000000..2be73c8fa
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useCreateLeadSyncSource.ts
@@ -0,0 +1,13 @@
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import createSource from "@/lib/api/client/app/leadsync/createSource";
+
+// Saves a new sync source and refreshes every source list.
+export default function useCreateLeadSyncSource() {
+    const qc = useQueryClient();
+    return useMutation({
+        mutationFn: createSource,
+        onSuccess: () => {
+            qc.invalidateQueries({ queryKey: ["lead-sync", "sources"] });
+        },
+    });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useDeleteLeadSyncSource.ts b/web/src/lib/api/hooks/app/leadsync/useDeleteLeadSyncSource.ts
new file mode 100644
index 000000000..a181e982f
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useDeleteLeadSyncSource.ts
@@ -0,0 +1,13 @@
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import deleteSource from "@/lib/api/client/app/leadsync/deleteSource";
+
+// Deletes a saved source and refreshes every source list.
+export default function useDeleteLeadSyncSource() {
+    const qc = useQueryClient();
+    return useMutation({
+        mutationFn: deleteSource,
+        onSuccess: () => {
+            qc.invalidateQueries({ queryKey: ["lead-sync", "sources"] });
+        },
+    });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useGoogleConnection.ts b/web/src/lib/api/hooks/app/leadsync/useGoogleConnection.ts
new file mode 100644
index 000000000..ea969a6a3
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useGoogleConnection.ts
@@ -0,0 +1,12 @@
+import { useQuery } from "@tanstack/react-query";
+import getGoogleConnection from "@/lib/api/client/app/leadsync/getGoogleConnection";
+
+// Reports whether the org has a connected google_sheets OAuth connection
+// usable for lead-sync. Drives the "Connect Google Sheets" vs sheet-picker UI.
+export default function useGoogleConnection() {
+    return useQuery({
+        queryKey: ["lead-sync", "google", "connection"],
+        queryFn: getGoogleConnection,
+        staleTime: 10_000,
+    });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useLeadSyncSources.ts b/web/src/lib/api/hooks/app/leadsync/useLeadSyncSources.ts
new file mode 100644
index 000000000..9f0037135
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useLeadSyncSources.ts
@@ -0,0 +1,12 @@
+import { useQuery } from "@tanstack/react-query";
+import listSources from "@/lib/api/client/app/leadsync/listSources";
+
+// Lists saved sync sources, optionally filtered to one campaign. Used by both
+// the global Contacts > Sync sources area and the per-campaign list.
+export default function useLeadSyncSources(campaignId?: string) {
+    return useQuery({
+        queryKey: ["lead-sync", "sources", campaignId ?? null],
+        queryFn: () => listSources(campaignId),
+        staleTime: 10_000,
+    });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useSheetMeta.ts b/web/src/lib/api/hooks/app/leadsync/useSheetMeta.ts
new file mode 100644
index 000000000..682956d8e
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useSheetMeta.ts
@@ -0,0 +1,13 @@
+import { useMutation } from "@tanstack/react-query";
+import getSpreadsheet from "@/lib/api/client/app/leadsync/getSpreadsheet";
+import previewSheet from "@/lib/api/client/app/leadsync/previewSheet";
+
+// Fetching spreadsheet metadata and previewing a tab are user-triggered
+// actions inside the wizard (not background queries), so they're mutations.
+export function useGetSpreadsheet() {
+    return useMutation({ mutationFn: getSpreadsheet });
+}
+
+export function usePreviewSheet() {
+    return useMutation({ mutationFn: previewSheet });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useSyncLeadSyncSource.ts b/web/src/lib/api/hooks/app/leadsync/useSyncLeadSyncSource.ts
new file mode 100644
index 000000000..6b663ad02
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useSyncLeadSyncSource.ts
@@ -0,0 +1,15 @@
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import syncSource from "@/lib/api/client/app/leadsync/syncSource";
+
+// "Sync now". On success, refreshes the source list (so last_synced_at /
+// last_result / status update) and contacts (new/updated rows landed).
+export default function useSyncLeadSyncSource() {
+    const qc = useQueryClient();
+    return useMutation({
+        mutationFn: syncSource,
+        onSuccess: () => {
+            qc.invalidateQueries({ queryKey: ["lead-sync", "sources"] });
+            qc.invalidateQueries({ queryKey: ["contacts"] });
+        },
+    });
+}
diff --git a/web/src/lib/api/hooks/app/leadsync/useUpdateLeadSyncSource.ts b/web/src/lib/api/hooks/app/leadsync/useUpdateLeadSyncSource.ts
new file mode 100644
index 000000000..7ac3a6730
--- /dev/null
+++ b/web/src/lib/api/hooks/app/leadsync/useUpdateLeadSyncSource.ts
@@ -0,0 +1,15 @@
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import updateSource from "@/lib/api/client/app/leadsync/updateSource";
+import type { UpdateLeadSyncSource } from "@/lib/api/models/app/leadsync/LeadSync";
+
+// Edits a saved source and refreshes every source list.
+export default function useUpdateLeadSyncSource() {
+    const qc = useQueryClient();
+    return useMutation({
+        mutationFn: (input: { id: string; body: UpdateLeadSyncSource }) =>
+            updateSource(input.id, input.body),
+        onSuccess: () => {
+            qc.invalidateQueries({ queryKey: ["lead-sync", "sources"] });
+        },
+    });
+}
diff --git a/web/src/lib/api/models/app/leadsync/LeadSync.ts b/web/src/lib/api/models/app/leadsync/LeadSync.ts
new file mode 100644
index 000000000..a73722486
--- /dev/null
+++ b/web/src/lib/api/models/app/leadsync/LeadSync.ts
@@ -0,0 +1,116 @@
+// Mirror of the backend's models/lead_sync.go shapes. Field names match the
+// JSON contract exactly. Lead-sync is an on-demand Google Sheet → contacts
+// importer: a saved "sync source" the user re-runs via a "Sync now" button.
+//
+// We deliberately REUSE the contact-import column-mapping + result types from
+// the import wizard rather than redeclaring them, so the same TargetPicker /
+// MapStep mapper and result rendering work verbatim against /google/preview
+// and /sources/:id/sync responses.
+
+import type {
+    ImportColumnMapping,
+    ImportDedupStrategy,
+    ImportPreview,
+    ImportResult,
+} from "@/lib/api/client/app/contacts/importContacts";
+
+// Re-export the reused contact-import types under lead-sync names so callers
+// can import everything lead-sync from one module.
+export type {
+    ImportColumnMapping,
+    ImportDedupStrategy,
+    ImportPreview,
+    ImportResult,
+};
+
+// LeadSyncStatus mirrors models.LeadSyncStatus. The synchronous SyncNow only
+// ever lands on idle/error; "syncing" exists for completeness/future async use.
+export type LeadSyncStatus = "idle" | "syncing" | "error";
+
+// A saved on-demand Google-Sheet → contacts source.
+export interface LeadSyncSource {
+    id: string;
+    organization_id: string;
+    created_by_user_id: string;
+    provider: string;
+    connection_id: string;
+    sheet_id: string;
+    sheet_title?: string;
+    tab_title?: string;
+    a1_range?: string;
+    has_header: boolean;
+    column_mapping: ImportColumnMapping[];
+    dedup: ImportDedupStrategy;
+    target_campaign_id?: string;
+    category_ids: string[];
+    subscribed_default: boolean;
+    label?: string;
+    status: LeadSyncStatus;
+    last_synced_at?: string;
+    last_result?: ImportResult;
+    last_error?: string;
+    created_at: string;
+    updated_at: string;
+}
+
+// Result of POST /sources/:id/sync.
+export interface LeadSyncResult {
+    source_id: string;
+    result: ImportResult;
+}
+
+// Reports whether the org has a connected (hidden) google_sheets OAuth
+// connection usable for lead-sync.
+export interface LeadSyncConnection {
+    connected: boolean;
+    connection: {
+        id: string;
+        external_account_name: string;
+        status: string;
+    } | null;
+}
+
+// One tab of a spreadsheet, from /google/spreadsheet.
+export interface SheetTab {
+    title: string;
+    index: number;
+}
+
+// Spreadsheet metadata returned by /google/spreadsheet — drives the tab picker.
+export interface SheetMeta {
+    sheet_id: string;
+    title: string;
+    tabs: SheetTab[];
+}
+
+// Request body for creating a new source.
+export interface CreateLeadSyncSource {
+    connection_id: string;
+    sheet_id: string;
+    sheet_title: string;
+    tab_title: string;
+    has_header: boolean;
+    column_mapping: ImportColumnMapping[];
+    dedup: ImportDedupStrategy;
+    target_campaign_id?: string;
+    category_ids: string[];
+    subscribed_default?: boolean;
+    label: string;
+}
+
+// Request body for PATCH — all fields optional; omitted ⇒ unchanged.
+// `clear_campaign: true` detaches the target campaign (a nil pointer alone
+// can't express "clear").
+export interface UpdateLeadSyncSource {
+    sheet_id?: string;
+    sheet_title?: string;
+    tab_title?: string;
+    has_header?: boolean;
+    column_mapping?: ImportColumnMapping[];
+    dedup?: ImportDedupStrategy;
+    target_campaign_id?: string;
+    clear_campaign?: boolean;
+    category_ids?: string[];
+    subscribed_default?: boolean;
+    label?: string;
+}