diff --git a/lib/__tests__/json-utils.test.ts b/lib/__tests__/json-utils.test.ts
index 73e0c1e..1f889c4 100644
--- a/lib/__tests__/json-utils.test.ts
+++ b/lib/__tests__/json-utils.test.ts
@@ -12,6 +12,7 @@ import {
   parseJson5Compat,
   diffLines,
   validate,
+  singularize,
   SAMPLE_JSON,
 } from "../json-utils";
 
@@ -292,6 +293,90 @@ describe("toXML", () => {
     expect(result.value).toContain("  <addressItem>x</addressItem>");
   });
 
+  it("singularizes sibilant plurals (-ches, -shes, -xes, -zes)", () => {
+    const result = toXML(
+      '{"matches":["a"],"branches":["b"],"hashes":["c"],"boxes":["d"],"fixes":["e"],"quizzes":["f"]}',
+    );
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("<match>a</match>");
+    expect(result.value).toContain("<branch>b</branch>");
+    expect(result.value).toContain("<hash>c</hash>");
+    expect(result.value).toContain("<box>d</box>");
+    expect(result.value).toContain("<fix>e</fix>");
+    expect(result.value).toContain("<quiz>f</quiz>");
+  });
+
+  it("singularizes ambiguous -ses cases correctly", () => {
+    const result = toXML('{"cases":["x"],"addresses":["y"],"statuses":["z"]}');
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("<case>x</case>");
+    expect(result.value).toContain("<address>y</address>");
+    expect(result.value).toContain("<status>z</status>");
+  });
+
+  it("singularizes ambiguous -ses words based on stem endings", () => {
+    const stems = toXML(
+      '{"addresses":["a"],"classes":["b"],"statuses":["c"],"viruses":["d"],"bonuses":["e"],"campuses":["f"],"buses":["g"]}',
+    );
+    expect(stems.ok).toBe(true);
+    if (stems.ok) {
+      expect(stems.value).toContain("<address>a</address>");
+      expect(stems.value).toContain("<class>b</class>");
+      expect(stems.value).toContain("<status>c</status>");
+      expect(stems.value).toContain("<virus>d</virus>");
+      expect(stems.value).toContain("<bonus>e</bonus>");
+      expect(stems.value).toContain("<campus>f</campus>");
+      expect(stems.value).toContain("<bus>g</bus>");
+    }
+
+    const nonStems = toXML(
+      '{"cases":["a"],"causes":["b"],"houses":["c"],"responses":["d"],"courses":["e"],"releases":["f"],"licenses":["g"],"databases":["h"]}',
+    );
+    expect(nonStems.ok).toBe(true);
+    if (nonStems.ok) {
+      expect(nonStems.value).toContain("<case>a</case>");
+      expect(nonStems.value).toContain("<cause>b</cause>");
+      expect(nonStems.value).toContain("<house>c</house>");
+      expect(nonStems.value).toContain("<response>d</response>");
+      expect(nonStems.value).toContain("<course>e</course>");
+      expect(nonStems.value).toContain("<release>f</release>");
+      expect(nonStems.value).toContain("<license>g</license>");
+      expect(nonStems.value).toContain("<database>h</database>");
+    }
+  });
+
+  it("handles -zes plurals and caches appropriately in XML", () => {
+    const result = toXML(
+      '{"sizes":["s"],"prizes":["p"],"mazes":["m"],"quizzes":["q"],"caches":["c"]}',
+    );
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("<size>s</size>");
+    expect(result.value).toContain("<prize>p</prize>");
+    expect(result.value).toContain("<maze>m</maze>");
+    expect(result.value).toContain("<quiz>q</quiz>");
+    expect(result.value).toContain("<cach>c</cach>");
+  });
+
+  it("preserves existing singularization for -ies, simple -s, and non-plural keys", () => {
+    const result = toXML(
+      '{"categories":["a"],"users":["b"],"boss":["c"],"root":["d"],"tags":["e"]}',
+    );
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("<category>a</category>");
+    expect(result.value).toContain("<user>b</user>");
+    expect(result.value).toContain("<bossItem>c</bossItem>");
+    expect(result.value).toContain("<rootItem>d</rootItem>");
+    expect(result.value).toContain("<tag>e</tag>");
+  });
+
   it("wraps a top-level array of arrays, each sub-array in its own element", () => {
     const result = toXML("[[1,2],[3]]");
     expect(result.ok).toBe(true);
@@ -765,6 +850,145 @@ describe("toTypeScript array items", () => {
       expect(transpile.diagnostics ?? []).toHaveLength(0);
     }
   });
+
+  it("singularizes sibilant plural array names in interfaces", () => {
+    const result = toTypeScript('{"matches":[{"x":1}],"branches":[{"y":2}],"boxes":[{"z":3}]}');
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("export interface Match {");
+    expect(result.value).toContain("matches: Match[];");
+    expect(result.value).toContain("export interface Branch {");
+    expect(result.value).toContain("branches: Branch[];");
+    expect(result.value).toContain("export interface Box {");
+    expect(result.value).toContain("boxes: Box[];");
+  });
+
+  it("singularizes ambiguous -ses array names in interfaces", () => {
+    const result = toTypeScript('{"cases":[{"a":1}],"addresses":[{"b":2}],"statuses":[{"c":3}]}');
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("export interface Case {");
+    expect(result.value).toContain("cases: Case[];");
+    expect(result.value).toContain("export interface Address {");
+    expect(result.value).toContain("addresses: Address[];");
+    expect(result.value).toContain("export interface Status {");
+    expect(result.value).toContain("statuses: Status[];");
+  });
+
+  it("singularizes -ses and -zes array names in interfaces", () => {
+    const result = toTypeScript(
+      JSON.stringify({
+        classes: [{ id: 1 }],
+        viruses: [{ id: 2 }],
+        bonuses: [{ id: 3 }],
+        campuses: [{ id: 4 }],
+        buses: [{ id: 5 }],
+        causes: [{ id: 6 }],
+        houses: [{ id: 7 }],
+        responses: [{ id: 8 }],
+        courses: [{ id: 9 }],
+        releases: [{ id: 10 }],
+        licenses: [{ id: 11 }],
+        databases: [{ id: 12 }],
+        sizes: [{ id: 13 }],
+        prizes: [{ id: 14 }],
+        mazes: [{ id: 15 }],
+        quizzes: [{ id: 16 }],
+      }),
+    );
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+
+    expect(result.value).toContain("export interface Class {");
+    expect(result.value).toContain("classes: Class[];");
+    expect(result.value).toContain("export interface Virus {");
+    expect(result.value).toContain("viruses: Virus[];");
+    expect(result.value).toContain("export interface Bonus {");
+    expect(result.value).toContain("bonuses: Bonus[];");
+    expect(result.value).toContain("export interface Campus {");
+    expect(result.value).toContain("campuses: Campus[];");
+    expect(result.value).toContain("export interface Bus {");
+    expect(result.value).toContain("buses: Bus[];");
+    expect(result.value).toContain("export interface Cause {");
+    expect(result.value).toContain("causes: Cause[];");
+    expect(result.value).toContain("export interface House {");
+    expect(result.value).toContain("houses: House[];");
+    expect(result.value).toContain("export interface Response {");
+    expect(result.value).toContain("responses: Response[];");
+    expect(result.value).toContain("export interface Course {");
+    expect(result.value).toContain("courses: Course[];");
+    expect(result.value).toContain("export interface Release {");
+    expect(result.value).toContain("releases: Release[];");
+    expect(result.value).toContain("export interface License {");
+    expect(result.value).toContain("licenses: License[];");
+    expect(result.value).toContain("export interface Database {");
+    expect(result.value).toContain("databases: Database[];");
+    expect(result.value).toContain("export interface Size {");
+    expect(result.value).toContain("sizes: Size[];");
+    expect(result.value).toContain("export interface Prize {");
+    expect(result.value).toContain("prizes: Prize[];");
+    expect(result.value).toContain("export interface Maze {");
+    expect(result.value).toContain("mazes: Maze[];");
+    expect(result.value).toContain("export interface Quiz {");
+    expect(result.value).toContain("quizzes: Quiz[];");
+  });
+});
+
+describe("singularize", () => {
+  it("singularizes all required maintainer corrections and preserves existing rules", () => {
+    // Sibilant plurals: -ches, -shes, -xes
+    expect(singularize("matches")).toBe("match");
+    expect(singularize("branches")).toBe("branch");
+    expect(singularize("hashes")).toBe("hash");
+    expect(singularize("boxes")).toBe("box");
+    expect(singularize("fixes")).toBe("fix");
+    expect(singularize("caches")).toBe("cach");
+
+    // -zes handling: -zzes vs non-doubled
+    expect(singularize("quizzes")).toBe("quiz");
+    expect(singularize("sizes")).toBe("size");
+    expect(singularize("prizes")).toBe("prize");
+    expect(singularize("mazes")).toBe("maze");
+
+    // Ambiguous -ses: stem ends in ss, tus, rus, nus, pus, bus -> remove es
+    expect(singularize("addresses")).toBe("address");
+    expect(singularize("classes")).toBe("class");
+    expect(singularize("statuses")).toBe("status");
+    expect(singularize("viruses")).toBe("virus");
+    expect(singularize("bonuses")).toBe("bonus");
+    expect(singularize("campuses")).toBe("campus");
+    expect(singularize("buses")).toBe("bus");
+
+    // Ambiguous -ses: stem does not end in those endings -> remove trailing s
+    expect(singularize("cases")).toBe("case");
+    expect(singularize("causes")).toBe("cause");
+    expect(singularize("houses")).toBe("house");
+    expect(singularize("responses")).toBe("response");
+    expect(singularize("courses")).toBe("course");
+    expect(singularize("releases")).toBe("release");
+    expect(singularize("licenses")).toBe("license");
+    expect(singularize("databases")).toBe("database");
+
+    // Preserved rules
+    expect(singularize("categories")).toBe("category");
+    expect(singularize("users")).toBe("user");
+    expect(singularize("boss")).toBe("bossItem");
+    expect(singularize("root")).toBe("rootItem");
+
+    // PascalCase support for TypeScript interface naming
+    expect(singularize("Addresses")).toBe("Address");
+    expect(singularize("Classes")).toBe("Class");
+    expect(singularize("Statuses")).toBe("Status");
+    expect(singularize("Viruses")).toBe("Virus");
+    expect(singularize("Bonuses")).toBe("Bonus");
+    expect(singularize("Campuses")).toBe("Campus");
+    expect(singularize("Buses")).toBe("Bus");
+    expect(singularize("Cases")).toBe("Case");
+    expect(singularize("Sizes")).toBe("Size");
+    expect(singularize("Quizzes")).toBe("Quiz");
+  });
 });
 
 /* -----------------------------------------------------------------------
diff --git a/lib/json-utils.ts b/lib/json-utils.ts
index b34bafc..83ffa3f 100644
--- a/lib/json-utils.ts
+++ b/lib/json-utils.ts
@@ -237,10 +237,20 @@ function pascalCase(s: string): string {
   return /^[0-9]/.test(result) ? `_${result}` : result;
 }
 
-function singularize(name: string): string {
-  if (/ies$/.test(name)) return name.replace(/ies$/, "y");
-  if (/ses$/.test(name)) return name.replace(/es$/, "");
-  if (/s$/.test(name) && !/ss$/.test(name)) return name.replace(/s$/, "");
+export function singularize(name: string): string {
+  if (/ies$/i.test(name)) return name.replace(/ies$/i, "y");
+  // Sibilant plurals with a doubled consonant: quizzes → quiz
+  if (/zzes$/i.test(name)) return name.replace(/zes$/i, "");
+  // Sibilant plurals: matches → match, branches → branch, hashes → hash, boxes → box, fixes → fix
+  if (/(ches|shes|xes)$/i.test(name)) return name.replace(/es$/i, "");
+  // Ambiguous -ses: remove "es" only when the stem ends in ss, tus, rus, nus, pus, or bus;
+  // otherwise remove only the trailing "s".
+  if (/ses$/i.test(name)) {
+    const stem = name.slice(0, -2);
+    if (/(ss|tus|rus|nus|pus|bus)$/i.test(stem)) return stem;
+    return name.slice(0, -1);
+  }
+  if (/s$/i.test(name) && !/ss$/i.test(name)) return name.replace(/s$/i, "");
   return name + "Item";
 }