diff --git a/src/app/api/labs/[id]/route.ts b/src/app/api/labs/[id]/route.ts
new file mode 100644
index 000000000..829f88498
--- /dev/null
+++ b/src/app/api/labs/[id]/route.ts
@@ -0,0 +1,188 @@
+import { NextRequest } from "next/server";
+
+import { apiHandler, requireAuth } from "@/lib/api-handler";
+import {
+  apiError,
+  apiSuccess,
+  getClientIp,
+  returnAllZodIssues,
+  safeJson,
+  sanitiseZodIssues,
+} from "@/lib/api-response";
+import { auditLog } from "@/lib/auth/audit";
+import { prisma } from "@/lib/db";
+import { decryptNoteFromBytes, encryptNoteToBytes } from "@/lib/labs/store";
+import { annotate } from "@/lib/logging/context";
+import {
+  classifyReferenceRange,
+  updateLabResultSchema,
+} from "@/lib/validations/labs";
+
+/**
+ * v1.17.1 — single lab-result resource (`/api/labs/{id}`).
+ *
+ * GET returns the row including its decrypted note (the detail view is the
+ * one place the plaintext note surfaces). PUT applies a partial edit
+ * (`data` built field-by-field; an explicit `null` clears `panel` / `note` /
+ * a reference bound, an omitted key leaves it untouched). DELETE soft-deletes
+ * by stamping `deletedAt`. Cross-user rows surface as 404 (existence sealed).
+ */
+
+type RouteParams = { params: Promise<{ id: string }> };
+
+export const GET = apiHandler(
+  async (_request: NextRequest, { params }: RouteParams) => {
+    const { user } = await requireAuth();
+    const { id } = await params;
+
+    const row = await prisma.labResult.findFirst({
+      where: { id, deletedAt: null },
+    });
+    if (!row || row.userId !== user.id) {
+      return apiError("Lab result not found", 404);
+    }
+
+    annotate({ action: { name: "labs.get" }, meta: { labResultId: id } });
+
+    return apiSuccess({
+      id: row.id,
+      panel: row.panel,
+      analyte: row.analyte,
+      value: row.value,
+      unit: row.unit,
+      referenceLow: row.referenceLow,
+      referenceHigh: row.referenceHigh,
+      takenAt: row.takenAt.toISOString(),
+      source: row.source,
+      note: row.noteEncrypted
+        ? decryptNoteFromBytes(row.noteEncrypted)
+        : null,
+      rangeStatus: classifyReferenceRange(
+        row.value,
+        row.referenceLow,
+        row.referenceHigh,
+      ),
+      createdAt: row.createdAt.toISOString(),
+      updatedAt: row.updatedAt.toISOString(),
+    });
+  },
+);
+
+export const PUT = apiHandler(
+  async (request: NextRequest, { params }: RouteParams) => {
+    const { user } = await requireAuth();
+    const { id } = await params;
+
+    const existing = await prisma.labResult.findFirst({
+      where: { id, deletedAt: null },
+    });
+    if (!existing || existing.userId !== user.id) {
+      return apiError("Lab result not found", 404);
+    }
+
+    const { data: body, error: jsonError } = await safeJson(request, {
+      maxBytes: 16 * 1024,
+    });
+    if (jsonError) return jsonError;
+
+    const parsed = updateLabResultSchema.safeParse(body);
+    if (!parsed.success) {
+      annotate({
+        action: { name: "labs.update.validation-failed" },
+        meta: { issue_count: parsed.error.issues.length, labResultId: id },
+      });
+      const auditIssues = sanitiseZodIssues(parsed.error.issues, {
+        stripValuesFromMessage: true,
+      });
+      prisma.auditLog
+        .create({
+          data: {
+            userId: user.id,
+            action: "labs.update.validation-failed",
+            details: JSON.stringify({ issues: auditIssues, labResultId: id }),
+          },
+        })
+        .catch(() => {
+          /* swallow — the 422 response is the contract */
+        });
+      return returnAllZodIssues(parsed.error, 422);
+    }
+
+    const d = parsed.data;
+
+    // Build `data` field-by-field. `undefined` → leave the column untouched;
+    // an explicit `null` on `panel` / `note` / a reference bound clears it.
+    const data: Record<string, unknown> = {};
+    if (d.panel !== undefined) data.panel = d.panel;
+    if (d.analyte !== undefined) data.analyte = d.analyte;
+    if (d.value !== undefined) data.value = d.value;
+    if (d.unit !== undefined) data.unit = d.unit;
+    if (d.referenceLow !== undefined) data.referenceLow = d.referenceLow;
+    if (d.referenceHigh !== undefined) data.referenceHigh = d.referenceHigh;
+    if (d.takenAt !== undefined) data.takenAt = d.takenAt;
+    if (d.note !== undefined) {
+      data.noteEncrypted = d.note ? encryptNoteToBytes(d.note) : null;
+    }
+
+    const updated = await prisma.labResult.update({ where: { id }, data });
+
+    await auditLog("labResult.update", {
+      userId: user.id,
+      ipAddress: getClientIp(request),
+      details: { labResultId: id },
+    });
+
+    annotate({ action: { name: "labs.update" }, meta: { labResultId: id } });
+
+    return apiSuccess({
+      id: updated.id,
+      panel: updated.panel,
+      analyte: updated.analyte,
+      value: updated.value,
+      unit: updated.unit,
+      referenceLow: updated.referenceLow,
+      referenceHigh: updated.referenceHigh,
+      takenAt: updated.takenAt.toISOString(),
+      source: updated.source,
+      hasNote: updated.noteEncrypted !== null,
+      rangeStatus: classifyReferenceRange(
+        updated.value,
+        updated.referenceLow,
+        updated.referenceHigh,
+      ),
+      createdAt: updated.createdAt.toISOString(),
+      updatedAt: updated.updatedAt.toISOString(),
+    });
+  },
+);
+
+export const DELETE = apiHandler(
+  async (request: NextRequest, { params }: RouteParams) => {
+    const { user } = await requireAuth();
+    const { id } = await params;
+
+    const existing = await prisma.labResult.findFirst({
+      where: { id, deletedAt: null },
+    });
+    if (!existing || existing.userId !== user.id) {
+      return apiError("Lab result not found", 404);
+    }
+
+    // Soft-delete: stamp `deletedAt`. Every read filters `deletedAt: null`,
+    // so the row is invisible from here on. A re-delete is idempotent.
+    await prisma.labResult.update({
+      where: { id },
+      data: { deletedAt: new Date() },
+    });
+
+    await auditLog("labResult.delete", {
+      userId: user.id,
+      ipAddress: getClientIp(request),
+      details: { labResultId: id, analyte: existing.analyte },
+    });
+
+    annotate({ action: { name: "labs.delete" }, meta: { labResultId: id } });
+
+    return apiSuccess({ deleted: true });
+  },
+);
diff --git a/src/app/api/labs/route.ts b/src/app/api/labs/route.ts
new file mode 100644
index 000000000..a80ff3f41
--- /dev/null
+++ b/src/app/api/labs/route.ts
@@ -0,0 +1,188 @@
+import { NextRequest } from "next/server";
+
+import { apiHandler, requireAuth } from "@/lib/api-handler";
+import {
+  apiSuccess,
+  getClientIp,
+  returnAllZodIssues,
+  safeJson,
+  sanitiseZodIssues,
+} from "@/lib/api-response";
+import { auditLog } from "@/lib/auth/audit";
+import { prisma } from "@/lib/db";
+import { withIdempotency } from "@/lib/idempotency";
+import { encryptNoteToBytes } from "@/lib/labs/store";
+import { annotate } from "@/lib/logging/context";
+import {
+  classifyReferenceRange,
+  createLabResultSchema,
+  listLabResultsSchema,
+} from "@/lib/validations/labs";
+
+/**
+ * v1.17.1 — structured lab-result store (`/api/labs`).
+ *
+ * GET lists the caller's live results with optional analyte / panel / date
+ * filters. POST records a single reading. `userId` is always narrowed from
+ * the session — never a body field — and the write `data` object is built
+ * field-by-field (no mass assignment). The free-text note, when present, is
+ * AES-256-GCM encrypted into the `noteEncrypted` Bytes column before write.
+ */
+
+// The serialised row never echoes the encrypted note bytes back; the badge
+// status is computed server-side so the client renders a coherent, neutral
+// in/out-of-range verdict without re-deriving the rule.
+function serialiseLabResult(row: {
+  id: string;
+  panel: string | null;
+  analyte: string;
+  value: number;
+  unit: string;
+  referenceLow: number | null;
+  referenceHigh: number | null;
+  takenAt: Date;
+  source: string;
+  noteEncrypted: Uint8Array | null;
+  createdAt: Date;
+  updatedAt: Date;
+}) {
+  return {
+    id: row.id,
+    panel: row.panel,
+    analyte: row.analyte,
+    value: row.value,
+    unit: row.unit,
+    referenceLow: row.referenceLow,
+    referenceHigh: row.referenceHigh,
+    takenAt: row.takenAt.toISOString(),
+    source: row.source,
+    hasNote: row.noteEncrypted !== null,
+    rangeStatus: classifyReferenceRange(
+      row.value,
+      row.referenceLow,
+      row.referenceHigh,
+    ),
+    createdAt: row.createdAt.toISOString(),
+    updatedAt: row.updatedAt.toISOString(),
+  };
+}
+
+export const GET = apiHandler(async (request: NextRequest) => {
+  const { user } = await requireAuth();
+
+  const params = Object.fromEntries(request.nextUrl.searchParams);
+  const parsed = listLabResultsSchema.safeParse(params);
+  if (!parsed.success) {
+    annotate({
+      action: { name: "labs.list.validation-failed" },
+      meta: { issue_count: parsed.error.issues.length },
+    });
+    return returnAllZodIssues(parsed.error, 422);
+  }
+
+  const { analyte, panel, from, to, limit, offset, sortDir } = parsed.data;
+
+  const where = {
+    userId: user.id,
+    deletedAt: null,
+    ...(analyte && { analyte }),
+    ...(panel && { panel }),
+    ...(from || to
+      ? {
+          takenAt: {
+            ...(from && { gte: from }),
+            ...(to && { lte: to }),
+          },
+        }
+      : {}),
+  };
+
+  const [rows, total] = await Promise.all([
+    prisma.labResult.findMany({
+      where,
+      orderBy: { takenAt: sortDir },
+      take: limit,
+      skip: offset,
+    }),
+    prisma.labResult.count({ where }),
+  ]);
+
+  annotate({
+    action: { name: "labs.list" },
+    meta: { total, limit, offset },
+  });
+
+  return apiSuccess({
+    results: rows.map(serialiseLabResult),
+    meta: { total, limit, offset },
+  });
+});
+
+export const POST = apiHandler(withIdempotency<[NextRequest]>(postLabResult));
+
+async function postLabResult(request: NextRequest) {
+  const { user } = await requireAuth();
+
+  const { data: body, error: jsonError } = await safeJson(request, {
+    maxBytes: 16 * 1024,
+  });
+  if (jsonError) return jsonError;
+
+  const parsed = createLabResultSchema.safeParse(body);
+  if (!parsed.success) {
+    annotate({
+      action: { name: "labs.create.validation-failed" },
+      meta: { issue_count: parsed.error.issues.length },
+    });
+    // Free-text `analyte` / `unit` / `note` could land verbatim in a Zod
+    // issue message — strip values from the audit-ledger breadcrumb.
+    const auditIssues = sanitiseZodIssues(parsed.error.issues, {
+      stripValuesFromMessage: true,
+    });
+    prisma.auditLog
+      .create({
+        data: {
+          userId: user.id,
+          action: "labs.create.validation-failed",
+          details: JSON.stringify({ issues: auditIssues }),
+        },
+      })
+      .catch(() => {
+        /* swallow — the 422 response is the contract */
+      });
+    return returnAllZodIssues(parsed.error, 422);
+  }
+
+  const { panel, analyte, value, unit, referenceLow, referenceHigh, takenAt, note } =
+    parsed.data;
+
+  // Field-by-field assignment — never spread `parsed.data`. `source` is
+  // hardcoded "MANUAL" for this user-facing path; import paths set their own.
+  const created = await prisma.labResult.create({
+    data: {
+      userId: user.id,
+      panel: panel ?? null,
+      analyte,
+      value,
+      unit,
+      referenceLow: referenceLow ?? null,
+      referenceHigh: referenceHigh ?? null,
+      takenAt,
+      source: "MANUAL",
+      noteEncrypted: note ? encryptNoteToBytes(note) : null,
+    },
+  });
+
+  await auditLog("labResult.create", {
+    userId: user.id,
+    ipAddress: getClientIp(request),
+    details: { labResultId: created.id, analyte: created.analyte },
+  });
+
+  annotate({
+    action: { name: "labs.create" },
+    meta: { labResultId: created.id },
+  });
+
+  return apiSuccess(serialiseLabResult(created), 201);
+}
diff --git a/src/lib/labs/store.ts b/src/lib/labs/store.ts
new file mode 100644
index 000000000..b50ab1e05
--- /dev/null
+++ b/src/lib/labs/store.ts
@@ -0,0 +1,71 @@
+/**
+ * v1.17.1 — server-side helpers for the structured lab-result store.
+ *
+ * Two concerns live here:
+ *
+ *   1. The AES-256-GCM ↔ `Bytes` codec for `LabResult.noteEncrypted`. The
+ *      free-text note is the only sensitive column on the model; it shares
+ *      the `encrypt()` string format (`"<keyId>.<base64>"`) every other
+ *      `*Encrypted` column uses, encoded as UTF-8 bytes.
+ *
+ *   2. `findLatestLabResultForAnalytes` — the read point the Vorsorge
+ *      annual-blood-panel reminder consults to decide whether a panel was
+ *      recorded inside its lead-time window. Exposed here, NOT coupled to
+ *      the reminder's code, so the reminder can mark itself satisfied
+ *      without this module taking a dependency on it.
+ */
+import { Buffer } from "node:buffer";
+
+import { decrypt, encrypt } from "@/lib/crypto";
+import { prisma } from "@/lib/db";
+
+/** Encrypt a UTF-8 note into the `Bytes` payload the schema stores. */
+export function encryptNoteToBytes(plaintext: string): Uint8Array<ArrayBuffer> {
+  const ciphertext = encrypt(plaintext);
+  const encoded = Buffer.from(ciphertext, "utf8");
+  // Prisma `Bytes` maps to `Uint8Array<ArrayBuffer>`; allocate a fresh
+  // ArrayBuffer-backed view so the structural type stays stable.
+  const out = new Uint8Array(new ArrayBuffer(encoded.byteLength));
+  out.set(encoded);
+  return out;
+}
+
+/** Decrypt a stored `Bytes` note back to plaintext. Throws on a bad key id. */
+export function decryptNoteFromBytes(buf: Uint8Array): string {
+  return decrypt(Buffer.from(buf).toString("utf8"));
+}
+
+/**
+ * Latest live (non-tombstoned) lab result for any of the given analytes,
+ * recorded at or after `since`. Returns the single most-recent matching
+ * row by `takenAt`, or `null` when no matching result exists in the window.
+ *
+ * Case-insensitive analyte match so "HbA1c" / "hba1c" resolve the same — a
+ * lab report's casing is not the user's concern. The Vorsorge reminder
+ * passes the analytes that satisfy an annual blood panel (e.g. an HbA1c or
+ * a lipid marker) plus the reminder's window start; a non-null return means
+ * the panel was recorded and the reminder can mark itself satisfied.
+ */
+export async function findLatestLabResultForAnalytes(
+  userId: string,
+  analytes: string[],
+  since: Date,
+): Promise<{ id: string; analyte: string; takenAt: Date } | null> {
+  if (analytes.length === 0) return null;
+  const candidates = await prisma.labResult.findMany({
+    where: {
+      userId,
+      deletedAt: null,
+      takenAt: { gte: since },
+      // Prisma has no case-insensitive `in`; match each analyte
+      // case-insensitively and let the DB OR them together.
+      OR: analytes.map((a) => ({
+        analyte: { equals: a, mode: "insensitive" as const },
+      })),
+    },
+    orderBy: { takenAt: "desc" },
+    take: 1,
+    select: { id: true, analyte: true, takenAt: true },
+  });
+  return candidates[0] ?? null;
+}
diff --git a/src/lib/query-keys/index.ts b/src/lib/query-keys/index.ts
index d864a42bd..7a8e73804 100644
--- a/src/lib/query-keys/index.ts
+++ b/src/lib/query-keys/index.ts
@@ -21,6 +21,7 @@ import { cycleKeys } from "./cycle";
 import { dashboardKeys } from "./dashboard";
 import { insightsKeys } from "./insights";
 import { integrationKeys } from "./integrations";
+import { labKeys } from "./labs";
 import { measurementKeys } from "./measurements";
 import { medicationKeys } from "./medications";
 import { moodKeys } from "./mood";
@@ -40,6 +41,7 @@ export const queryKeys = {
   ...workoutKeys,
   ...settingsKeys,
   ...cycleKeys,
+  ...labKeys,
 };
 
 /**
diff --git a/src/lib/query-keys/labs.ts b/src/lib/query-keys/labs.ts
new file mode 100644
index 000000000..374b59753
--- /dev/null
+++ b/src/lib/query-keys/labs.ts
@@ -0,0 +1,33 @@
+/**
+ * v1.17.1 — TanStack Query keys for the structured lab-result store.
+ *
+ * `labResultsList` bakes the filter + pagination shape into the key so a
+ * filter change refetches without a same-key cache collision (the project's
+ * queryKey-factory invariant).
+ */
+export const labKeys = {
+  labResults: () => ["lab-results"] as const,
+
+  labResultsList: (params: {
+    analyte: string | undefined;
+    panel: string | undefined;
+    from: string | undefined;
+    to: string | undefined;
+    page: number;
+    sortDir: string;
+  }) =>
+    [
+      "lab-results",
+      "list",
+      params.analyte ?? null,
+      params.panel ?? null,
+      params.from ?? null,
+      params.to ?? null,
+      params.page,
+      params.sortDir,
+    ] as const,
+
+  /** Per-analyte trend series (≥2 values) shown inline on a grouped card. */
+  labAnalyteTrend: (analyte: string) =>
+    ["lab-results", "trend", analyte] as const,
+};
diff --git a/src/lib/validations/__tests__/labs.test.ts b/src/lib/validations/__tests__/labs.test.ts
new file mode 100644
index 000000000..712ce8328
--- /dev/null
+++ b/src/lib/validations/__tests__/labs.test.ts
@@ -0,0 +1,174 @@
+import { describe, it, expect } from "vitest";
+
+import {
+  classifyReferenceRange,
+  createLabResultSchema,
+  listLabResultsSchema,
+  updateLabResultSchema,
+} from "../labs";
+
+const FUTURE = new Date(Date.now() + 60 * 60 * 1000).toISOString();
+const RECENT = new Date(Date.now() - 60 * 60 * 1000).toISOString();
+
+describe("createLabResultSchema", () => {
+  it("accepts a minimal valid reading", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "HbA1c",
+      value: 5.4,
+      unit: "%",
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(true);
+  });
+
+  it("normalises a backdatable takenAt to a Date", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "LDL",
+      value: 110,
+      unit: "mg/dL",
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(true);
+    if (r.success) expect(r.data.takenAt).toBeInstanceOf(Date);
+  });
+
+  it("rejects a future takenAt", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "LDL",
+      value: 110,
+      unit: "mg/dL",
+      takenAt: FUTURE,
+    });
+    expect(r.success).toBe(false);
+  });
+
+  it("rejects an empty analyte", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "   ",
+      value: 1,
+      unit: "%",
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(false);
+  });
+
+  it("rejects a transposed reference range (low > high)", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "Ferritin",
+      value: 50,
+      unit: "ng/mL",
+      referenceLow: 300,
+      referenceHigh: 30,
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(false);
+  });
+
+  it("accepts a single (upper-only) reference bound", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "LDL",
+      value: 110,
+      unit: "mg/dL",
+      referenceHigh: 116,
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(true);
+  });
+
+  it("normalises an empty-string panel to undefined", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "TSH",
+      value: 2,
+      unit: "mIU/L",
+      panel: "",
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(true);
+    if (r.success) expect(r.data.panel).toBeUndefined();
+  });
+
+  it("rejects a non-finite value", () => {
+    const r = createLabResultSchema.safeParse({
+      analyte: "LDL",
+      value: Number.POSITIVE_INFINITY,
+      unit: "mg/dL",
+      takenAt: RECENT,
+    });
+    expect(r.success).toBe(false);
+  });
+});
+
+describe("updateLabResultSchema", () => {
+  it("accepts an explicit null to clear panel + note", () => {
+    const r = updateLabResultSchema.safeParse({ panel: null, note: null });
+    expect(r.success).toBe(true);
+    if (r.success) {
+      expect(r.data.panel).toBeNull();
+      expect(r.data.note).toBeNull();
+    }
+  });
+
+  it("accepts a partial value-only edit", () => {
+    const r = updateLabResultSchema.safeParse({ value: 5.6 });
+    expect(r.success).toBe(true);
+  });
+
+  it("still enforces the range order when both bounds are supplied", () => {
+    const r = updateLabResultSchema.safeParse({
+      referenceLow: 10,
+      referenceHigh: 1,
+    });
+    expect(r.success).toBe(false);
+  });
+});
+
+describe("listLabResultsSchema", () => {
+  it("defaults limit/offset/sortDir", () => {
+    const r = listLabResultsSchema.safeParse({});
+    expect(r.success).toBe(true);
+    if (r.success) {
+      expect(r.data.limit).toBe(100);
+      expect(r.data.offset).toBe(0);
+      expect(r.data.sortDir).toBe("desc");
+    }
+  });
+
+  it("caps limit at 500", () => {
+    const r = listLabResultsSchema.safeParse({ limit: "9999" });
+    expect(r.success).toBe(false);
+  });
+});
+
+describe("classifyReferenceRange", () => {
+  it("returns unknown when no bounds are given", () => {
+    expect(classifyReferenceRange(5, null, null)).toBe("unknown");
+    expect(classifyReferenceRange(5, undefined, undefined)).toBe("unknown");
+  });
+
+  it("returns in-range inside both bounds", () => {
+    expect(classifyReferenceRange(5, 4, 6)).toBe("in-range");
+  });
+
+  it("treats the bounds as inclusive", () => {
+    expect(classifyReferenceRange(4, 4, 6)).toBe("in-range");
+    expect(classifyReferenceRange(6, 4, 6)).toBe("in-range");
+  });
+
+  it("returns below when under the low bound", () => {
+    expect(classifyReferenceRange(3.9, 4, 6)).toBe("below");
+  });
+
+  it("returns above when over the high bound", () => {
+    expect(classifyReferenceRange(6.1, 4, 6)).toBe("above");
+  });
+
+  it("classifies against a single upper bound", () => {
+    expect(classifyReferenceRange(120, null, 116)).toBe("above");
+    expect(classifyReferenceRange(100, null, 116)).toBe("in-range");
+  });
+
+  it("classifies against a single lower bound", () => {
+    expect(classifyReferenceRange(8, 10, null)).toBe("below");
+    expect(classifyReferenceRange(12, 10, null)).toBe("in-range");
+  });
+});
diff --git a/src/lib/validations/labs.ts b/src/lib/validations/labs.ts
new file mode 100644
index 000000000..fde18bc7c
--- /dev/null
+++ b/src/lib/validations/labs.ts
@@ -0,0 +1,169 @@
+/**
+ * v1.17.1 — structured lab-result store.
+ *
+ * A minimal, generic `LabResult` capture path: a self-hoster records a
+ * biomarker reading (HbA1c, LDL, ferritin, TSH, …) with its value, unit,
+ * the lab's reference range, and the sample date. Pairs with the v1.17.1
+ * Vorsorge annual-blood-panel reminder, which otherwise has nowhere to
+ * record the result it reminds the user to obtain.
+ *
+ * The model is intentionally free-form on `analyte` + `unit` (no closed
+ * LOINC enum): a lab report prints whatever name and unit it likes, and a
+ * forced taxonomy would reject real-world values. The optional `panel`
+ * groups analytes that arrived together (e.g. "Großes Blutbild").
+ */
+import { z } from "zod/v4";
+
+import { validateEntryInstant } from "@/lib/validations/entry-instant";
+
+/**
+ * Far-past floor for a lab sample. A self-hoster legitimately backdates an
+ * old paper report, so the window is generous (50 years) but still rejects
+ * epoch-zero / corrupted-import instants via the shared 1900 floor.
+ */
+const LAB_TAKEN_AT_MAX_AGE_MS = 50 * 365.25 * 24 * 60 * 60 * 1000;
+
+/** Shared `takenAt` field: ISO string → Date, plausibility-bounded. */
+const takenAtField = validateEntryInstant(
+  z
+    .string()
+    .datetime({ message: "takenAt must be an ISO 8601 datetime" })
+    .transform((s) => new Date(s)),
+  {
+    maxAgeMs: LAB_TAKEN_AT_MAX_AGE_MS,
+    pastMessage: "Sample date is too far in the past",
+  },
+);
+
+/** Trimmed, bounded free-text field with a min-length guard. */
+const requiredText = (max: number) =>
+  z
+    .string()
+    .trim()
+    .min(1)
+    .max(max);
+
+const optionalPanel = z
+  .string()
+  .trim()
+  .min(1)
+  .max(120)
+  .optional()
+  // An empty-string panel is normalised to "no panel" so the grouping
+  // stays NULL-distinct rather than carrying a blank label.
+  .or(z.literal("").transform(() => undefined));
+
+const optionalNote = z
+  .string()
+  .trim()
+  .max(2000)
+  .optional()
+  .or(z.literal("").transform(() => undefined));
+
+/**
+ * Reference bounds are independently optional (a lab may report only an
+ * upper bound, e.g. LDL < 116). When BOTH are present the low bound must
+ * not exceed the high bound — a transposed range is a client error.
+ */
+const referenceLow = z.number().finite().optional();
+const referenceHigh = z.number().finite().optional();
+
+export const createLabResultSchema = z
+  .object({
+    panel: optionalPanel,
+    analyte: requiredText(120),
+    value: z.number().finite(),
+    unit: requiredText(40),
+    referenceLow,
+    referenceHigh,
+    takenAt: takenAtField,
+    note: optionalNote,
+  })
+  .refine(
+    (d) =>
+      d.referenceLow === undefined ||
+      d.referenceHigh === undefined ||
+      d.referenceLow <= d.referenceHigh,
+    {
+      message: "referenceLow must not exceed referenceHigh",
+      path: ["referenceLow"],
+    },
+  );
+
+export type CreateLabResultInput = z.infer<typeof createLabResultSchema>;
+
+/**
+ * Update schema: every field optional (partial edit). `panel` and `note`
+ * accept an explicit `null` to clear the stored value — distinct from an
+ * omitted key, which leaves the column untouched.
+ */
+export const updateLabResultSchema = z
+  .object({
+    panel: optionalPanel.or(z.null()),
+    analyte: requiredText(120).optional(),
+    value: z.number().finite().optional(),
+    unit: requiredText(40).optional(),
+    referenceLow: referenceLow.or(z.null()),
+    referenceHigh: referenceHigh.or(z.null()),
+    takenAt: takenAtField.optional(),
+    note: optionalNote.or(z.null()),
+  })
+  .refine(
+    (d) =>
+      d.referenceLow === undefined ||
+      d.referenceLow === null ||
+      d.referenceHigh === undefined ||
+      d.referenceHigh === null ||
+      d.referenceLow <= d.referenceHigh,
+    {
+      message: "referenceLow must not exceed referenceHigh",
+      path: ["referenceLow"],
+    },
+  );
+
+export type UpdateLabResultInput = z.infer<typeof updateLabResultSchema>;
+
+/** List query: filter by analyte (exact) + date range, paginate. */
+export const listLabResultsSchema = z.object({
+  analyte: z.string().trim().min(1).max(120).optional(),
+  panel: z.string().trim().min(1).max(120).optional(),
+  from: z
+    .string()
+    .datetime()
+    .transform((s) => new Date(s))
+    .optional(),
+  to: z
+    .string()
+    .datetime()
+    .transform((s) => new Date(s))
+    .optional(),
+  limit: z.coerce.number().int().min(1).max(500).default(100),
+  offset: z.coerce.number().int().min(0).default(0),
+  sortDir: z.enum(["asc", "desc"]).default("desc"),
+});
+
+export type ListLabResultsInput = z.infer<typeof listLabResultsSchema>;
+
+/**
+ * Reference-range classification. Deliberately a three-state, NEUTRAL
+ * verdict — the badge that renders it must stay calm and informative, NOT
+ * alarming (no red "out of range" tint). `"unknown"` when the lab reported
+ * no usable bounds.
+ *
+ * Bounds are treated as inclusive: a value exactly on the reference limit
+ * reads as in-range, matching how labs print "≤" / "≥" reference notation.
+ */
+export type ReferenceRangeStatus = "in-range" | "below" | "above" | "unknown";
+
+export function classifyReferenceRange(
+  value: number,
+  referenceLow: number | null | undefined,
+  referenceHigh: number | null | undefined,
+): ReferenceRangeStatus {
+  const hasLow = referenceLow !== null && referenceLow !== undefined;
+  const hasHigh = referenceHigh !== null && referenceHigh !== undefined;
+  if (!hasLow && !hasHigh) return "unknown";
+  if (hasLow && value < (referenceLow as number)) return "below";
+  if (hasHigh && value > (referenceHigh as number)) return "above";
+  return "in-range";
+}