backend: prescription start/end dates + dispense ledger

Add optional startDate/endDate columns to prescriptions (schema,
validation, types, service) — when set, endDate drives expiry.

Add a new append-only `dispenses` resource (schema, types, validation,
service, route at /api/dispenses) recording who received which medication,
gated on the existing inventory RBAC statement. Migration 0020.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/services/dispenses.ts

@@ -0,0 +1,61 @@
+import { desc, eq } from "drizzle-orm";
+
+import { db } from "../db/index.js";
+import { dispenses } from "../db/schema/dispenses.js";
+import type { DispenseInput } from "../lib/dispense-validation.js";
+import type { Dispense } from "../types/dispense.js";
+
+type DispenseRow = typeof dispenses.$inferSelect;
+
+function toDispense(row: DispenseRow): Dispense {
+  return {
+    id: row.id,
+    fileNumber: row.patientFileNumber,
+    name: row.patientName,
+    initials: row.patientInitials,
+    medication: row.medication,
+    dose: row.dose,
+    quantity: row.quantity,
+    unit: row.unit,
+    prescriptionId: row.prescriptionId,
+    dispensedBy: row.dispensedBy,
+    dispensedByName: row.dispensedByName,
+    dispensedAt: row.dispensedAt.toISOString(),
+    notes: row.notes,
+    createdAt: row.createdAt.toISOString(),
+  };
+}
+
+export async function listDispenses(orgId: string): Promise<Dispense[]> {
+  const rows = await db
+    .select()
+    .from(dispenses)
+    .where(eq(dispenses.organizationId, orgId))
+    .orderBy(desc(dispenses.dispensedAt));
+  return rows.map(toDispense);
+}
+
+export async function createDispense(
+  orgId: string,
+  dispenser: { id: string; name: string },
+  input: DispenseInput,
+): Promise<Dispense> {
+  const [row] = await db
+    .insert(dispenses)
+    .values({
+      organizationId: orgId,
+      patientFileNumber: input.fileNumber,
+      patientName: input.name,
+      patientInitials: input.initials,
+      medication: input.medication,
+      dose: input.dose,
+      quantity: input.quantity,
+      unit: input.unit,
+      prescriptionId: input.prescriptionId ?? null,
+      dispensedBy: dispenser.id,
+      dispensedByName: dispenser.name,
+      notes: input.notes ?? null,
+    })
+    .returning();
+  return toDispense(row!);
+}

backend/src/services/prescriptions.ts

@@ -22,6 +22,8 @@ function toPrescription(row: PrescriptionRow): Prescription {
     frequency: row.frequency,
     prescriber: row.prescriber,
     prescribedAt: row.prescribedAt,
+    startDate: row.startDate,
+    endDate: row.endDate,
     status: row.status,
     duration: row.duration,
     notes: row.notes,
@@ -45,6 +47,8 @@ function columns(orgId: string, input: PrescriptionInput, createdBy?: string) {
     duration: input.duration ?? null,
     notes: input.notes ?? null,
     source: input.source,
+    startDate: input.startDate ?? null,
+    endDate: input.endDate ?? null,
     // Only set prescribedAt when supplied; otherwise the column default (today).
     ...(input.prescribedAt ? { prescribedAt: input.prescribedAt } : {}),
     ...(createdBy ? { createdBy } : {}),