diff --git a/src/pages/api/v1/monitoring/ingest.ts b/src/pages/api/v1/monitoring/ingest.ts
new file mode 100644
index 0000000..2d707db
--- /dev/null
+++ b/src/pages/api/v1/monitoring/ingest.ts
@@ -0,0 +1,168 @@
+import { randomUUID } from 'node:crypto';
+import type { APIRoute } from 'astro';
+
+import type {
+  IsoUtcTimestamp,
+  OsohAuditTrailRecord,
+  OsohMonitoringEventRecord,
+  OsohStoreState,
+} from '../../../../../lib/server/osoh-store';
+import {
+  createEmptyOsohStoreState,
+} from '../../../../../lib/server/osoh-store';
+import {
+  resolveIngestAuth,
+  validateIngestPayload,
+} from '../../../../../lib/server/osoh-ingest';
+
+export const prerender = false;
+
+type RouteStage = 'auth' | 'validation' | 'accepted';
+
+type RouteErrorReason =
+  | 'missing_token'
+  | 'unknown_token'
+  | 'revoked_token'
+  | 'inactive_site'
+  | 'invalid_scope'
+  | 'invalid_json'
+  | 'invalid_payload'
+  | 'missing_event_type'
+  | 'invalid_event_type'
+  | 'missing_occurred_at'
+  | 'invalid_occurred_at'
+  | 'missing_payload_body'
+  | 'invalid_payload_body';
+
+const json = (body: unknown, status: number): Response =>
+  new Response(JSON.stringify(body), {
+    status,
+    headers: {
+      'content-type': 'application/json; charset=utf-8',
+      'cache-control': 'no-store',
+    },
+  });
+
+const nowIso = (): IsoUtcTimestamp => new Date().toISOString();
+
+const loadOsohStoreState = async (): Promise<OsohStoreState> => {
+  return createEmptyOsohStoreState();
+};
+
+const appendMonitoringEvent = async (
+  state: OsohStoreState,
+  event: OsohMonitoringEventRecord,
+): Promise<void> => {
+  state.monitoringEvents.push(event);
+};
+
+const appendAuditTrailRecord = async (
+  state: OsohStoreState,
+  record: OsohAuditTrailRecord,
+): Promise<void> => {
+  state.auditTrail.push(record);
+};
+
+const auditAuthFailure = async (
+  state: OsohStoreState,
+  reason: Extract<
+    RouteErrorReason,
+    'missing_token' | 'unknown_token' | 'revoked_token' | 'inactive_site' | 'invalid_scope'
+  >,
+): Promise<void> => {
+  await appendAuditTrailRecord(state, {
+    auditId: randomUUID(),
+    siteId: 'unknown',
+    action: 'site_updated',
+    occurredAt: nowIso(),
+    details: {
+      category: 'ingest_auth_failure',
+      reason,
+    },
+  });
+};
+
+export const POST: APIRoute = async ({ request }) => {
+  const state = await loadOsohStoreState();
+
+  const authResult = resolveIngestAuth(
+    state,
+    request.headers.get('authorization') ?? undefined,
+  );
+
+  if (!authResult.ok) {
+    await auditAuthFailure(state, authResult.reason);
+
+    return json(
+      {
+        ok: false,
+        stage: 'auth' satisfies RouteStage,
+        reason: authResult.reason satisfies RouteErrorReason,
+      },
+      401,
+    );
+  }
+
+  let body: unknown;
+
+  try {
+    body = await request.json();
+  } catch {
+    return json(
+      {
+        ok: false,
+        stage: 'validation' satisfies RouteStage,
+        reason: 'invalid_json' satisfies RouteErrorReason,
+      },
+      400,
+    );
+  }
+
+  const validationResult = validateIngestPayload(body);
+
+  if (!validationResult.ok) {
+    return json(
+      {
+        ok: false,
+        stage: 'validation' satisfies RouteStage,
+        reason: validationResult.reason satisfies RouteErrorReason,
+      },
+      400,
+    );
+  }
+
+  const receivedAt = nowIso();
+  const eventId = randomUUID();
+
+  await appendMonitoringEvent(state, {
+    eventId,
+    siteId: authResult.siteId,
+    eventType: validationResult.normalized.eventType,
+    occurredAt: validationResult.normalized.occurredAt,
+    receivedAt,
+    payload: validationResult.normalized.payload,
+  });
+
+  await appendAuditTrailRecord(state, {
+    auditId: randomUUID(),
+    siteId: authResult.siteId,
+    action: 'site_updated',
+    occurredAt: receivedAt,
+    details: {
+      category: 'ingest_event_accepted',
+      eventId,
+      eventType: validationResult.normalized.eventType,
+    },
+  });
+
+  return json(
+    {
+      ok: true,
+      stage: 'accepted' satisfies RouteStage,
+      eventId,
+      siteId: authResult.siteId,
+      receivedAt,
+    },
+    202,
+  );
+};