the serial letter normalization added to the code to normalize the Heh , Ya , Kaf and etc to the correct character

src/utils/plate-normalizer/plate-normalizer.service.ts

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+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;
+  }
+}