diff --git a/scripts/verify-plate-normalization.mjs b/scripts/verify-plate-normalization.mjs
new file mode 100644
index 0000000..dce8581
--- /dev/null
+++ b/scripts/verify-plate-normalization.mjs
@@ -0,0 +1,86 @@
+#!/usr/bin/env node
+/**
+ * Quick manual verification for plate normalization.
+ *
+ * Usage:  node scripts/verify-plate-normalization.mjs
+ *
+ * Demonstrates that:
+ *   339ه‍77  (ه + U+200D)  ->  339ه77  ->  letter ه -> code 15
+ *   339ي77   (Arabic ي)    ->  339ی77  ->  letter ی -> code 16
+ */
+
+// ---------- paste the pure function here so no build needed ----------
+function normalizePlateText(text) {
+  if (!text) return text;
+  let result = String(text);
+  result = result.normalize("NFKC");
+  result = result.replace(/[\u200C\u200D\u200E\u200F\uFEFF]/g, "");
+  result = result.replace(/\u064A/g, "\u06CC"); // Arabic ي → Persian ی
+  result = result.trim();
+  return result;
+}
+
+// ---------- the canonical plate-letter → code mapping ----------
+const PLATE_LETTER_MAP = {
+  الف: 1, ب: 2, پ: 3, ج: 4, د: 5,
+  س: 6, ص: 7, ط: 8, ع: 9, ق: 10,
+  ل: 11, م: 12, ن: 13, و: 14, ه: 15,
+  ی: 16, ک: 17, ژ: 18, ت: 19, ث: 20,
+  ز: 21, ش: 22, ف: 23, گ: 24,
+};
+
+function extractAndMap(plateString) {
+  const normalized = normalizePlateText(plateString);
+
+  // Simple parser: digits | letter | digits  (left+right digits, 1 letter)
+  const match = normalized.match(/^(\d+)([^\d]+)(\d+)$/);
+  if (!match) return { input: plateString, normalized, error: "no match" };
+
+  const [, leftDigits, letterRaw, rightDigits] = match;
+  const letter = normalizePlateText(letterRaw);
+  const code = PLATE_LETTER_MAP[letter];
+
+  return {
+    input: plateString,
+    normalized,
+    leftDigits,
+    letter,
+    rightDigits,
+    code,
+    ok: code !== undefined,
+  };
+}
+
+// ---------- test cases ----------
+const cases = [
+  { desc: "ه + ZWJ (the original bug)", plate: "339ه\u200D77" },
+  { desc: "Arabic ي → Persian ی",        plate: "339ي77" },
+  { desc: "ه + ZWNJ",                    plate: "339ه\u200C77" },
+  { desc: "RTL mark around letter",      plate: "339\u200Fه\u200E77" },
+  { desc: "BOM + ZWJ combined",          plate: "\uFEFF339ه\u200D77" },
+  { desc: "clean letter (no junk)",       plate: "339ه77" },
+  { desc: "full plate: الف",             plate: "11الف22" },
+  { desc: "full plate: ی",               plate: "55ی99" },
+];
+
+console.log("Plate Normalization Verification\n");
+console.log("=".repeat(72));
+
+let allPassed = true;
+for (const { desc, plate } of cases) {
+  const r = extractAndMap(plate);
+  const status = r.ok ? "PASS" : "FAIL";
+  if (!r.ok) allPassed = false;
+
+  console.log(`\n[${status}] ${desc}`);
+  console.log(`  Input:     ${JSON.stringify(plate)}`);
+  console.log(`  Normalized: ${JSON.stringify(r.normalized)}`);
+  if (r.letter) {
+    console.log(`  Letter:    ${r.letter}  (U+${r.letter.charCodeAt(0).toString(16).toUpperCase().padStart(4, "0")})`);
+  }
+  console.log(`  Code:      ${r.code ?? "undefined"}`);
+}
+
+console.log("\n" + "=".repeat(72));
+console.log(allPassed ? "\n  All tests PASSED ✓" : "\n  Some tests FAILED ✗");
+process.exit(allPassed ? 0 : 1);
diff --git a/src/claim-request-management/claim-request-management.module.ts b/src/claim-request-management/claim-request-management.module.ts
index a61076f..552c58f 100644
--- a/src/claim-request-management/claim-request-management.module.ts
+++ b/src/claim-request-management/claim-request-management.module.ts
@@ -57,6 +57,7 @@ import { JwtModule } from "@nestjs/jwt";
 import { MediaPolicyModule } from "src/media-policy/media-policy.module";
 import { FanavaranAuditModule } from "src/fanavaran/fanavaran-audit.module";
 import { FanavaranLookupModule } from "src/fanavaran/fanavaran-lookup.module";
+import { PlateNormalizerModule } from "src/utils/plate-normalizer/plate-normalizer.module";
 
 @Module({
   imports: [
@@ -67,6 +68,7 @@ import { FanavaranLookupModule } from "src/fanavaran/fanavaran-lookup.module";
     }),
     FanavaranAuditModule,
     FanavaranLookupModule,
+    PlateNormalizerModule,
     PublicIdModule,
     UsersModule,
     RequestManagementModule,
diff --git a/src/claim-request-management/claim-request-management.service.ts b/src/claim-request-management/claim-request-management.service.ts
index 1509ae9..36e6e6d 100644
--- a/src/claim-request-management/claim-request-management.service.ts
+++ b/src/claim-request-management/claim-request-management.service.ts
@@ -156,6 +156,7 @@ import {
   resolvePartCaptureIndex,
 } from "src/helpers/outer-damage-parts";
 import { normalizeMoneyAmountString } from "src/utils/unicode-digits";
+import { PlateNormalizerService } from "src/utils/plate-normalizer/plate-normalizer.service";
 
 import {
   CAPTURE_PHASE_DAMAGED_PARTY_DOC_KEYS,
@@ -352,6 +353,7 @@ export class ClaimRequestManagementService {
     private readonly fanavaranLookupService: FanavaranLookupService,
     private readonly fileMakerDbService: FileMakerDbService,
     private readonly fieldExpertDbService: FieldExpertDbService,
+    private readonly plateNormalizer: PlateNormalizerService,
   ) {}
 
   private requiredDocumentKeysV2(isCarBody: boolean): string[] {
@@ -503,7 +505,7 @@ export class ClaimRequestManagementService {
     const ir = Number(irRaw);
     const leftDigits = Number(leftRaw);
     const centerDigits = Number(centerRaw);
-    const centerAlphabet = String(alphaRaw || "").trim();
+    const centerAlphabet = this.plateNormalizer.normalizePlateText(String(alphaRaw || ""));
     if (
       !Number.isFinite(ir) ||
       !Number.isFinite(leftDigits) ||
@@ -530,11 +532,11 @@ export class ClaimRequestManagementService {
       Number.isFinite(Number(p.leftDigits)) &&
       Number.isFinite(Number(p.centerDigits)) &&
       Number.isFinite(Number(p.ir)) &&
-      String(p.centerAlphabet || "").trim()
+      this.plateNormalizer.normalizePlateText(String(p.centerAlphabet || ""))
     ) {
       return {
         leftDigits: Number(p.leftDigits),
-        centerAlphabet: String(p.centerAlphabet).trim(),
+        centerAlphabet: this.plateNormalizer.normalizePlateText(String(p.centerAlphabet)),
         centerDigits: Number(p.centerDigits),
         ir: Number(p.ir),
       };
@@ -3602,9 +3604,10 @@ export class ClaimRequestManagementService {
     if (centerAlphabet == null) return null;
     const raw = String(centerAlphabet).trim();
     if (!raw) return null;
-    const asNumber = Number(raw);
+    const normalized = this.plateNormalizer.normalizePlateText(raw);
+    const asNumber = Number(normalized);
     if (Number.isFinite(asNumber)) return asNumber;
-    return FANAVARAN_PLATE_LETTER_CODE[raw] ?? null;
+    return this.plateNormalizer.resolvePlateLetterCode(normalized, FANAVARAN_PLATE_LETTER_CODE);
   }
 
   private formatFanavaranPlateNo(
diff --git a/src/plates/plates.module.ts b/src/plates/plates.module.ts
index 4da9f75..53db18b 100644
--- a/src/plates/plates.module.ts
+++ b/src/plates/plates.module.ts
@@ -4,6 +4,7 @@ import { ClientModule } from "src/client/client.module";
 import { PlateDbService } from "src/plates/entites/db-service/plate.db.service";
 import { SandHubModule } from "src/sand-hub/sand-hub.module";
 import { UsersModule } from "src/users/users.module";
+import { PlateNormalizerModule } from "src/utils/plate-normalizer/plate-normalizer.module";
 import { PlatesModel, PlatesSchema } from "./entites/schema/plate.schema";
 import { PlatesService } from "./plates.service";
 
@@ -12,6 +13,7 @@ import { PlatesService } from "./plates.service";
     UsersModule,
     SandHubModule,
     ClientModule,
+    PlateNormalizerModule,
     MongooseModule.forFeature([
       { name: PlatesModel.name, schema: PlatesSchema },
     ]),
diff --git a/src/plates/plates.service.ts b/src/plates/plates.service.ts
index e6ffd11..e41695a 100644
--- a/src/plates/plates.service.ts
+++ b/src/plates/plates.service.ts
@@ -7,20 +7,23 @@ import {
 import { Types } from "mongoose";
 import { PlateDbService } from "src/plates/entites/db-service/plate.db.service";
 import { AddPlateDto } from "src/profile/dto/user/AddPlateDto";
+import { PlateNormalizerService } from "src/utils/plate-normalizer/plate-normalizer.service";
 
 @Injectable()
 export class PlatesService {
   constructor(
     private readonly plateDbService: PlateDbService,
+    private readonly plateNormalizer: PlateNormalizerService,
   ) {}
 
   async addPlate(currentUser, body: AddPlateDto) {
     const { plate, nationalCodeOfInsurer } = body;
 
+    const normalizedAlphabet = this.plateNormalizer.normalizePlateText(String(plate.centerAlphabet || ""));
     const duplicate = await this.plateDbService.findOne({
       userId: currentUser,
       leftDigits: plate.leftDigits,
-      centerAlphabet: plate.centerAlphabet,
+      centerAlphabet: normalizedAlphabet,
       centerDigits: plate.centerDigits,
       ir: plate.ir,
       nationalCodeOfInsurer,
@@ -31,6 +34,7 @@ export class PlatesService {
 
     const newPlateData = await this.plateDbService.create({
       ...plate,
+      centerAlphabet: normalizedAlphabet,
       userId: currentUser,
       nationalCodeOfInsurer: body.nationalCodeOfInsurer,
     });
diff --git a/src/request-management/inquiry-refresh.service.ts b/src/request-management/inquiry-refresh.service.ts
index 5353c37..525949b 100644
--- a/src/request-management/inquiry-refresh.service.ts
+++ b/src/request-management/inquiry-refresh.service.ts
@@ -7,6 +7,7 @@ import {
 import { Types } from "mongoose";
 import { ClaimCaseDbService } from "src/claim-request-management/entites/db-service/claim-case.db.service";
 import { SandHubService } from "src/sand-hub/sand-hub.service";
+import { PlateNormalizerService } from "src/utils/plate-normalizer/plate-normalizer.service";
 import { BlameRequestType } from "src/Types&Enums/blame-request-management/blameRequestType.enum";
 import { BlameRequestDbService } from "./entities/db-service/blame-request.db.service";
 import { PartyRole } from "./entities/schema/partyRole.enum";
@@ -33,6 +34,7 @@ export class InquiryRefreshService {
     private readonly blameRequestDbService: BlameRequestDbService,
     private readonly claimCaseDbService: ClaimCaseDbService,
     private readonly sandHubService: SandHubService,
+    private readonly plateNormalizer: PlateNormalizerService,
   ) {}
 
   async reinquiryInquiries(
@@ -592,7 +594,7 @@ export class InquiryRefreshService {
         centerDigits !== undefined &&
         ir !== undefined
       ) {
-        const plateLetter = String(centerAlphabet).trim();
+        const plateLetter = this.plateNormalizer.normalizePlateText(String(centerAlphabet));
         const parsed: PlateParts = {
           leftDigits: Number(leftDigits),
           centerAlphabet: plateLetter,
@@ -622,8 +624,7 @@ export class InquiryRefreshService {
     const ir = Number(irRaw);
     const leftDigits = Number(leftRaw);
     const centerDigits = Number(centerRaw);
-    const centerAlphabet = String(alphaRaw || "").trim();
-
+    const centerAlphabet = this.plateNormalizer.normalizePlateText(String(alphaRaw || ""));
     if (
       !Number.isFinite(ir) ||
       !Number.isFinite(leftDigits) ||
diff --git a/src/request-management/request-management.module.ts b/src/request-management/request-management.module.ts
index 9da5a2d..c93a8a7 100644
--- a/src/request-management/request-management.module.ts
+++ b/src/request-management/request-management.module.ts
@@ -12,6 +12,7 @@ import { UsersModule } from "src/users/users.module";
 import { CronModule } from "src/utils/cron/cron.module";
 import { PublicIdModule } from "src/utils/public-id/public-id.module";
 import { HashModule } from "src/utils/hash/hash.module";
+import { PlateNormalizerModule } from "src/utils/plate-normalizer/plate-normalizer.module";
 import { SmsOrchestrationModule } from "src/sms-orchestration/sms-orchestration.module";
 import { WorkflowStepManagementModule } from "src/workflow-step-management/workflow-step-management.module";
 import { AuthModule } from "src/auth/auth.module";
@@ -59,6 +60,7 @@ import { InquiryRefreshService } from "./inquiry-refresh.service";
     SmsOrchestrationModule,
     PublicIdModule,
     HashModule,
+    PlateNormalizerModule,
     WorkflowStepManagementModule,
     PlatesModule,
     MulterModule.register({
diff --git a/src/sand-hub/sand-hub.module.ts b/src/sand-hub/sand-hub.module.ts
index dbc48fc..3b2dc12 100644
--- a/src/sand-hub/sand-hub.module.ts
+++ b/src/sand-hub/sand-hub.module.ts
@@ -5,6 +5,7 @@ import { createHttpModuleOptions } from "src/core/config/http-proxy.factory";
 import { MongooseModule } from "@nestjs/mongoose";
 import { ClientModule } from "src/client/client.module";
 import { SystemSettingsModule } from "src/system-settings/system-settings.module";
+import { PlateNormalizerModule } from "src/utils/plate-normalizer/plate-normalizer.module";
 import { SandHubDbService } from "src/sand-hub/entity/db-service/sand-hub.db.service";
 import { SandHubModel, SandHubSchema } from "./entity/schema/sand-hub.schema";
 import { SandHubService } from "./sand-hub.service";
@@ -17,6 +18,7 @@ import { SandHubService } from "./sand-hub.service";
       useFactory: createHttpModuleOptions,
     }),
     SystemSettingsModule,
+    PlateNormalizerModule,
     ClientModule,
     MongooseModule.forFeature([
       { name: SandHubModel.name, schema: SandHubSchema },
diff --git a/src/sand-hub/sand-hub.service.spec.ts b/src/sand-hub/sand-hub.service.spec.ts
index 3e09e01..1392658 100644
--- a/src/sand-hub/sand-hub.service.spec.ts
+++ b/src/sand-hub/sand-hub.service.spec.ts
@@ -9,6 +9,9 @@ describe("SandHubService inquiry mocks", () => {
     isInquiryLive: jest.fn(),
     getMockCompanyContext: jest.fn(),
   };
+  const plateNormalizer = {
+    normalizePlateText: (text: string) => text,
+  };
 
   let service: SandHubService;
 
@@ -30,6 +33,7 @@ describe("SandHubService inquiry mocks", () => {
       httpService as any,
       sandHubDbService as any,
       externalInquirySettings as unknown as ExternalInquirySettingsService,
+      plateNormalizer as any,
     );
     externalInquirySettings.isInquiryLive.mockResolvedValue(false);
     externalInquirySettings.getMockCompanyContext.mockResolvedValue({
diff --git a/src/sand-hub/sand-hub.service.ts b/src/sand-hub/sand-hub.service.ts
index a6f8b5e..6925b65 100644
--- a/src/sand-hub/sand-hub.service.ts
+++ b/src/sand-hub/sand-hub.service.ts
@@ -12,6 +12,7 @@ import {
 import { SandHubDbService } from "src/sand-hub/entity/db-service/sand-hub.db.service";
 import { SandHubModel } from "src/sand-hub/entity/schema/sand-hub.schema";
 import { ExternalInquirySettingsService } from "src/client/external-inquiry-settings.service";
+import { PlateNormalizerService } from "src/utils/plate-normalizer/plate-normalizer.service";
 import type { ExternalInquiryType } from "src/common/types/external-inquiry.types";
 import type { MockInquiryCompanyContext } from "src/common/types/external-inquiry.types";
 import { SandHubDetailDto, SandHubInquiryOptions } from "./dto/sand-hub.dto";
@@ -39,6 +40,7 @@ export class SandHubService {
     private readonly httpService: HttpService,
     private readonly sandHubDbService: SandHubDbService,
     private readonly externalInquirySettings: ExternalInquirySettingsService,
+    private readonly plateNormalizer: PlateNormalizerService,
   ) {}
 
   private clientRefFrom(options?: SandHubInquiryOptions): string | undefined {
@@ -162,8 +164,8 @@ export class SandHubService {
       nationalCodeOfInsurer: nationalCode,
       plate: {
         leftDigits: Number(payload.part1 ?? payload.leftTwoDigits ?? 16),
-        centerAlphabet: String(
-          payload.part2 ?? payload.serialLetter ?? "12",
+        centerAlphabet: this.plateNormalizer.normalizePlateText(
+          String(payload.part2 ?? payload.serialLetter ?? "12"),
         ),
         centerDigits: Number(payload.part3 ?? payload.threeDigits ?? 498),
         ir: Number(payload.part4 ?? payload.rightTwoDigits ?? 60),
diff --git a/src/utils/plate-normalizer/plate-normalizer.module.ts b/src/utils/plate-normalizer/plate-normalizer.module.ts
new file mode 100644
index 0000000..f73e135
--- /dev/null
+++ b/src/utils/plate-normalizer/plate-normalizer.module.ts
@@ -0,0 +1,8 @@
+import { Module } from "@nestjs/common";
+import { PlateNormalizerService } from "./plate-normalizer.service";
+
+@Module({
+  providers: [PlateNormalizerService],
+  exports: [PlateNormalizerService],
+})
+export class PlateNormalizerModule {}
diff --git a/src/utils/plate-normalizer/plate-normalizer.service.ts b/src/utils/plate-normalizer/plate-normalizer.service.ts
new file mode 100644
index 0000000..7f9ae1f
--- /dev/null
+++ b/src/utils/plate-normalizer/plate-normalizer.service.ts
@@ -0,0 +1,79 @@
+import { Injectable, Logger } from "@nestjs/common";
+
+/**
+ * Characters stripped from plate text during normalization.
+ * These invisible Unicode code-points can sneak in via copy-paste
+ * or OCR and break exact-match lookups against the plate letter map.
+ */
+const INVISIBLE_CHARS = [
+  "\u200C", // Zero-Width Non-Joiner
+  "\u200D", // Zero-Width Joiner
+  "\u200E", // Left-to-Right Mark
+  "\u200F", // Right-to-Left Mark
+  "\uFEFF", // BOM / Zero-Width No-Break Space
+];
+
+const INVISIBLE_RE = new RegExp(`[${INVISIBLE_CHARS.join("")}]`, "g");
+
+/**
+ * Normalize a Persian license-plate character (or short text) so that
+ * visually-identical Unicode variants collapse to the canonical form
+ * used in the plate letter mapping.
+ *
+ * Steps (in order):
+ * 1. NFKC normalization  — folds compatibility equivalents
+ * 2. Strip invisible Unicode characters (ZWJ, ZWNJ, LTR/RTL marks, BOM)
+ * 3. Convert Arabic ي (U+064A) → Persian ی (U+06CC)
+ * 4. Trim leading/trailing whitespace
+ */
+export function normalizePlateText(text: string): string {
+  if (!text) return text;
+
+  let result = String(text);
+
+  // 1. Unicode NFKC normalization
+  result = result.normalize("NFKC");
+
+  // 2. Remove invisible characters
+  result = result.replace(INVISIBLE_RE, "");
+
+  // 3. Arabic ي → Persian ی
+  result = result.replace(/\u064A/g, "\u06CC");
+
+  // 4. Trim whitespace
+  result = result.trim();
+
+  return result;
+}
+
+@Injectable()
+export class PlateNormalizerService {
+  private readonly logger = new Logger(PlateNormalizerService.name);
+
+  /** @see module-level {@link normalizePlateText} */
+  normalizePlateText(text: string): string {
+    return normalizePlateText(text);
+  }
+
+  /**
+   * Normalize a plate letter and, if it doesn't resolve in the given
+   * mapping, log the raw Unicode code-points for debugging.
+   *
+   * @returns the numeric code from `mapping`, or `null` when the letter
+   *          is unknown after normalization.
+   */
+  resolvePlateLetterCode(
+    letter: string,
+    mapping: Record<string, number>,
+  ): number | null {
+    const normalized = this.normalizePlateText(letter);
+
+    const code = mapping[normalized];
+    if (code !== undefined) return code;
+
+    this.logger.debug(
+      `Unknown plate letter: ${normalized} [${Array.from(normalized).map((c) => `U+${c.charCodeAt(0).toString(16).toUpperCase().padStart(4, "0")}`).join(", ")}]`,
+    );
+    return null;
+  }
+}
diff --git a/src/utils/plate-normalizer/plate-normalizer.spec.ts b/src/utils/plate-normalizer/plate-normalizer.spec.ts
new file mode 100644
index 0000000..6351c66
--- /dev/null
+++ b/src/utils/plate-normalizer/plate-normalizer.spec.ts
@@ -0,0 +1,131 @@
+import { PlateNormalizerService, normalizePlateText } from "./plate-normalizer.service";
+
+describe("normalizePlateText (pure function)", () => {
+  it("returns unchanged text for a clean plate letter", () => {
+    expect(normalizePlateText("ه")).toBe("ه");
+    expect(normalizePlateText("الف")).toBe("الف");
+  });
+
+  it("strips Zero-Width Joiner (U+200D)", () => {
+    // ه + ZWJ  — the exact scenario from the issue
+    const input = "ه\u200D";
+    expect(normalizePlateText(input)).toBe("ه");
+  });
+
+  it("strips Zero-Width Non-Joiner (U+200C)", () => {
+    expect(normalizePlateText("ه\u200C")).toBe("ه");
+  });
+
+  it("strips Left-to-Right Mark (U+200E)", () => {
+    expect(normalizePlateText("ه\u200E")).toBe("ه");
+  });
+
+  it("strips Right-to-Left Mark (U+200F)", () => {
+    expect(normalizePlateText("ه\u200F")).toBe("ه");
+  });
+
+  it("strips BOM (U+FEFF)", () => {
+    expect(normalizePlateText("\uFEFFه")).toBe("ه");
+  });
+
+  it("converts Arabic ي (U+064A) to Persian ی (U+06CC)", () => {
+    expect(normalizePlateText("\u064A")).toBe("\u06CC");
+  });
+
+  it("does not alter already-Persian ی (U+06CC)", () => {
+    expect(normalizePlateText("\u06CC")).toBe("\u06CC");
+  });
+
+  it("handles a full plate string: 339ه\u200D77 → 339ه77", () => {
+    expect(normalizePlateText("339ه\u200D77")).toBe("339ه77");
+  });
+
+  it("handles multiple invisible chars interleaved", () => {
+    const input = "\u200F339\u200Cه\u200D\uFEFF77\u200E";
+    expect(normalizePlateText(input)).toBe("339ه77");
+  });
+
+  it("trims whitespace", () => {
+    expect(normalizePlateText("  ه  ")).toBe("ه");
+  });
+
+  it("applies NFKC normalization", () => {
+    // Full-width digit ３ (U+FF13) → ASCII 3
+    expect(normalizePlateText("３")).toBe("3");
+  });
+
+  it("returns empty string for empty input", () => {
+    expect(normalizePlateText("")).toBe("");
+  });
+});
+
+describe("PlateNormalizerService", () => {
+  let service: PlateNormalizerService;
+
+  beforeEach(() => {
+    service = new PlateNormalizerService();
+  });
+
+  describe("normalizePlateText", () => {
+    it("delegates to the pure function", () => {
+      expect(service.normalizePlateText("ه\u200D")).toBe("ه");
+    });
+  });
+
+  describe("resolvePlateLetterCode", () => {
+    const PLATE_LETTER_MAP: Record<string, number> = {
+      "\u0627\u0644\u0641": 1, // الف
+      "\u0628": 2,
+      "\u067E": 3,
+      "\u062C": 4,
+      "\u062F": 5,
+      "\u0633": 6,
+      "\u0635": 7,
+      "\u0637": 8,
+      "\u0639": 9,
+      "\u0642": 10,
+      "\u0644": 11,
+      "\u0645": 12,
+      "\u0646": 13,
+      "\u0648": 14,
+      "\u0647": 15, // ه
+      "\u06CC": 16, // ی
+      "\u06A9": 17,
+      "\u0698": 18,
+      "\u062A": 19,
+      "\u062B": 20,
+      "\u0632": 21,
+      "\u0634": 22,
+      "\u0641": 23,
+      "\u06AF": 24,
+    };
+
+    it("returns 15 for clean ه", () => {
+      expect(service.resolvePlateLetterCode("ه", PLATE_LETTER_MAP)).toBe(15);
+    });
+
+    it("returns 15 for ه + ZWJ (the bug scenario)", () => {
+      expect(service.resolvePlateLetterCode("ه\u200D", PLATE_LETTER_MAP)).toBe(
+        15,
+      );
+    });
+
+    it("returns 16 for Arabic ي (mapped to Persian ی)", () => {
+      expect(
+        service.resolvePlateLetterCode("\u064A", PLATE_LETTER_MAP),
+      ).toBe(16);
+    });
+
+    it("returns null for an unknown letter and logs it", () => {
+      const spy = jest.spyOn(
+        (service as any).logger,
+        "debug",
+      );
+      expect(service.resolvePlateLetterCode("؟", PLATE_LETTER_MAP)).toBeNull();
+      expect(spy).toHaveBeenCalledWith(
+        expect.stringContaining("Unknown plate letter"),
+      );
+      spy.mockRestore();
+    });
+  });
+});