diff --git a/package.json b/package.json
index 28c8399..7029b89 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,7 @@
 {
   "name": "@iklab/testkit",
-  "version": "1.0.0",
+
+  "version": "1.1.0",
   "description": "Test quality toolkit — boundary values, flakiness prediction, duplicate detection, static test scanner.",
   "author": "Ihor Kosheliev",
   "license": "MIT",
diff --git a/src/__tests__/boundaries.test.ts b/src/__tests__/boundaries.test.ts
index 1d2f105..a28f9e9 100644
--- a/src/__tests__/boundaries.test.ts
+++ b/src/__tests__/boundaries.test.ts
@@ -464,3 +464,39 @@ describe("boundaries — structure", () => {
     }
   });
 });
+
+describe("boundaries.custom", () => {
+  it("returns provided values", () => {
+    const result = boundaries.custom({
+      valid: [18, 25, 65],
+      invalid: [-1, 0, 17, 151],
+      boundary: [18, 150],
+    });
+    expect(result.valid).toEqual([18, 25, 65]);
+    expect(result.invalid).toEqual([-1, 0, 17, 151]);
+    expect(result.boundary).toEqual([18, 150]);
+  });
+
+  it("defaults boundary to empty array", () => {
+    const result = boundaries.custom({
+      valid: ["a"],
+      invalid: [""],
+    });
+    expect(result.boundary).toEqual([]);
+  });
+
+  it("throws on missing valid array", () => {
+    expect(() => boundaries.custom({ valid: null as any, invalid: [] })).toThrow(TypeError);
+  });
+
+  it("throws on missing invalid array", () => {
+    expect(() => boundaries.custom({ valid: [], invalid: null as any })).toThrow(TypeError);
+  });
+
+  it("works with testEach", () => {
+    const { testEach } = require("../test-each");
+    const result = boundaries.custom({ valid: [1], invalid: [0], boundary: [1] });
+    const rows = testEach(result);
+    expect(rows.length).toBeGreaterThan(0);
+  });
+});
diff --git a/src/__tests__/coverage.test.ts b/src/__tests__/coverage.test.ts
new file mode 100644
index 0000000..a8d51d9
--- /dev/null
+++ b/src/__tests__/coverage.test.ts
@@ -0,0 +1,64 @@
+import { coverage } from "../coverage";
+
+describe("coverage", () => {
+  it("matches tests to requirements", () => {
+    const result = coverage(
+      ["should login with valid credentials", "should show error for wrong password"],
+      ["User can login", "User sees error on invalid password", "User can reset password"],
+      { threshold: 0.2 }
+    );
+    expect(result.coveragePercent).toBe(67);
+    expect(result.covered).toHaveLength(2);
+    expect(result.uncovered).toEqual(["User can reset password"]);
+  });
+
+  it("returns 100% when all requirements covered", () => {
+    const result = coverage(
+      ["should create user", "should delete user"],
+      ["Create user", "Delete user"]
+    );
+    expect(result.coveragePercent).toBe(100);
+    expect(result.uncovered).toHaveLength(0);
+  });
+
+  it("returns 0% when nothing matches", () => {
+    const result = coverage(
+      ["should render homepage"],
+      ["User can upload avatar"]
+    );
+    expect(result.coveragePercent).toBe(0);
+    expect(result.uncovered).toHaveLength(1);
+  });
+
+  it("handles empty arrays", () => {
+    expect(coverage([], []).coveragePercent).toBe(100);
+    expect(coverage(["test"], []).coveragePercent).toBe(100);
+    expect(coverage([], ["req"]).coveragePercent).toBe(0);
+  });
+
+  it("respects custom threshold", () => {
+    const result = coverage(
+      ["should show products"],
+      ["Display product catalog"],
+      { threshold: 0.5 }
+    );
+    // Higher threshold = fewer matches
+    expect(result.coveragePercent).toBeLessThanOrEqual(100);
+  });
+
+  it("provides mapping with matched tests", () => {
+    const result = coverage(
+      ["should create user account", "should validate email"],
+      ["User registration"],
+      { threshold: 0.2 }
+    );
+    expect(result.mapping).toHaveLength(1);
+    expect(result.mapping[0].requirement).toBe("User registration");
+    expect(result.mapping[0].covered).toBe(true);
+  });
+
+  it("throws on invalid input", () => {
+    expect(() => coverage(null as any, [])).toThrow(TypeError);
+    expect(() => coverage([], null as any)).toThrow(TypeError);
+  });
+});
diff --git a/src/__tests__/suggest.test.ts b/src/__tests__/suggest.test.ts
new file mode 100644
index 0000000..5e7fa1a
--- /dev/null
+++ b/src/__tests__/suggest.test.ts
@@ -0,0 +1,43 @@
+import { suggest } from "../suggest";
+
+describe("suggest", () => {
+  it("suggests negative case for create operations", () => {
+    const result = suggest("should create a new user");
+    expect(result.suggestions.some(s => s.includes("negative"))).toBe(true);
+  });
+
+  it("suggests auth for login-related tests", () => {
+    const result = suggest("should login with valid credentials");
+    expect(result.suggestions.some(s => s.includes("auth"))).toBe(true);
+  });
+
+  it("suggests boundary for search operations", () => {
+    const result = suggest("should search products by name");
+    expect(result.suggestions.some(s => s.includes("boundary") || s.includes("special characters"))).toBe(true);
+  });
+
+  it("suggests file edge cases for upload operations", () => {
+    const result = suggest("should upload user avatar");
+    expect(result.suggestions.some(s => s.includes("file") || s.includes("oversized"))).toBe(true);
+  });
+
+  it("suggests error handling for payment operations", () => {
+    const result = suggest("should process payment checkout");
+    expect(result.suggestions.some(s => s.includes("error") || s.includes("fail"))).toBe(true);
+  });
+
+  it("returns generic suggestions for vague descriptions", () => {
+    const result = suggest("should work");
+    expect(result.suggestions.length).toBeGreaterThan(0);
+  });
+
+  it("returns generic suggestions for empty input", () => {
+    const result = suggest("");
+    expect(result.suggestions).toHaveLength(4);
+  });
+
+  it("score reflects number of suggestions", () => {
+    const result = suggest("should create user");
+    expect(result.score).toBe(result.suggestions.length);
+  });
+});
diff --git a/src/boundaries.ts b/src/boundaries.ts
index 31980a1..f382b8d 100644
--- a/src/boundaries.ts
+++ b/src/boundaries.ts
@@ -282,4 +282,14 @@ export const boundaries = {
   password: passwordBoundaries,
   phone: phoneBoundaries,
   uuid: uuidBoundaries,
+  custom(rules: { valid: unknown[]; invalid: unknown[]; boundary?: unknown[] }): BoundaryResult {
+    if (!rules || !Array.isArray(rules.valid) || !Array.isArray(rules.invalid)) {
+      throw new TypeError("custom() requires { valid: unknown[], invalid: unknown[] }");
+    }
+    return {
+      valid: [...rules.valid],
+      invalid: [...rules.invalid],
+      boundary: rules.boundary ? [...rules.boundary] : [],
+    };
+  },
 };
diff --git a/src/coverage.ts b/src/coverage.ts
new file mode 100644
index 0000000..858f09b
--- /dev/null
+++ b/src/coverage.ts
@@ -0,0 +1,48 @@
+import type { CoverageResult, CoverageMapping } from "./types";
+
+export function coverage(
+  tests: string[],
+  requirements: string[],
+  options?: { threshold?: number }
+): CoverageResult {
+  const threshold = Math.max(0, Math.min(1, options?.threshold ?? 0.3));
+
+  if (!Array.isArray(tests) || !Array.isArray(requirements)) {
+    throw new TypeError("coverage() requires arrays of strings");
+  }
+
+  const mapping: CoverageMapping[] = requirements.map((req) => {
+    const matchedTests = tests
+      .map((test, idx) => ({ test, idx, sim: similarity(req, test) }))
+      .filter((m) => m.sim >= threshold)
+      .sort((a, b) => b.sim - a.sim)
+      .map((m) => m.test);
+    return { requirement: req, matchedTests, covered: matchedTests.length > 0 };
+  });
+
+  const covered = mapping.filter((m) => m.covered).map((m) => m.requirement);
+  const uncovered = mapping.filter((m) => !m.covered).map((m) => m.requirement);
+  const coveragePercent = requirements.length > 0
+    ? Math.round((covered.length / requirements.length) * 100)
+    : 100;
+
+  return { covered, uncovered, coveragePercent, mapping };
+}
+
+// Local Jaccard similarity (same algorithm as duplicates.ts but decoupled)
+function tokenize(text: string): Set<string> {
+  const STOP_WORDS = new Set(["a","an","the","is","are","was","were","be","been","being","have","has","had","do","does","did","will","would","could","should","may","might","shall","can","need","must","to","of","in","for","on","with","at","by","from","as","into","about","between","through","after","before","during","and","but","or","not","no","it","its","this","that","these","those","i","we","you","he","she","they","my","our","your"]);
+  return new Set(
+    text.toLowerCase().replace(/[^a-z0-9\s]/g, " ").split(/\s+/).filter((w) => w.length > 1 && !STOP_WORDS.has(w))
+  );
+}
+
+function similarity(a: string, b: string): number {
+  const setA = tokenize(a);
+  const setB = tokenize(b);
+  if (setA.size === 0 || setB.size === 0) return 0;
+  let intersection = 0;
+  for (const token of setA) if (setB.has(token)) intersection++;
+  const union = new Set([...setA, ...setB]).size;
+  return union > 0 ? intersection / union : 0;
+}
diff --git a/src/index.ts b/src/index.ts
index 1fc7565..7357d29 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,6 +2,8 @@ export { boundaries } from "./boundaries";
 export { flaky } from "./flaky";
 export { testEach } from "./test-each";
 export { detectDuplicates } from "./duplicates";
+export { coverage } from "./coverage";
+export { suggest } from "./suggest";
 
 export type {
   BoundaryResult,
@@ -18,4 +20,7 @@ export type {
   DuplicateOptions,
   TestEachOptions,
   TestEachRow,
+  CoverageResult,
+  CoverageMapping,
+  SuggestionResult,
 } from "./types";
diff --git a/src/suggest.ts b/src/suggest.ts
new file mode 100644
index 0000000..871a7b4
--- /dev/null
+++ b/src/suggest.ts
@@ -0,0 +1,52 @@
+import type { SuggestionResult } from "./types";
+
+const PATTERNS: { pattern: RegExp; category: string; suggestion: string }[] = [
+  { pattern: /^should\s+(create|add|save|insert|post|submit|register|sign.?up)/i, category: "negative", suggestion: "Consider negative case: what happens with invalid or missing input?" },
+  { pattern: /^should\s+(update|edit|modify|change|patch)/i, category: "negative", suggestion: "Consider negative case: what if the resource doesn't exist?" },
+  { pattern: /^should\s+(delete|remove|destroy)/i, category: "negative", suggestion: "Consider negative case: what if the resource is already deleted?" },
+  { pattern: /^should\s+(display|show|render|list|get|fetch|load|read)/i, category: "empty", suggestion: "Consider edge case: what if the result is empty or null?" },
+  { pattern: /^should\s+(search|filter|sort|find)/i, category: "boundary", suggestion: "Consider boundary: what about empty query, very long query, or special characters?" },
+  { pattern: /login|auth|sign.?in|session|token/i, category: "auth", suggestion: "Consider auth: what if the user is not authenticated or session expired?" },
+  { pattern: /upload|file|image|attachment|document/i, category: "file", suggestion: "Consider edge case: what about empty files, oversized files, or unsupported formats?" },
+  { pattern: /payment|checkout|order|cart|price|billing/i, category: "error", suggestion: "Consider error handling: what if payment fails or times out?" },
+  { pattern: /email|notification|sms|message/i, category: "async", suggestion: "Consider async: what if delivery fails or is delayed?" },
+  { pattern: /permission|role|access|admin/i, category: "auth", suggestion: "Consider authorization: what if user lacks required permissions?" },
+  { pattern: /pagination|page|scroll|infinite|load.?more/i, category: "boundary", suggestion: "Consider boundary: first page, last page, empty page, page beyond max." },
+  { pattern: /concurrent|parallel|simultaneous|race/i, category: "concurrency", suggestion: "Consider concurrency: what if two users perform the same action simultaneously?" },
+];
+
+// Generic suggestions when no specific patterns match
+const GENERIC: string[] = [
+  "Consider negative case: what happens when input is invalid?",
+  "Consider edge case: empty or null values.",
+  "Consider boundary values: min, max, zero, one.",
+  "Consider error handling: what if the operation fails?",
+];
+
+export function suggest(description: string): SuggestionResult {
+  if (typeof description !== "string" || description.trim().length === 0) {
+    return { suggestions: GENERIC, score: GENERIC.length };
+  }
+
+  const matched = new Map<string, string>();
+  for (const p of PATTERNS) {
+    if (p.pattern.test(description) && !matched.has(p.category)) {
+      matched.set(p.category, p.suggestion);
+    }
+  }
+
+  // Always check for missing common aspects
+  const lower = description.toLowerCase();
+  if (!lower.includes("error") && !lower.includes("fail") && !lower.includes("invalid") && !matched.has("negative")) {
+    matched.set("negative", "Consider negative case: what happens with invalid input?");
+  }
+  if (!lower.includes("empty") && !lower.includes("null") && !lower.includes("zero") && !lower.includes("none") && !matched.has("empty")) {
+    matched.set("empty", "Consider edge case: empty, null, or zero values.");
+  }
+  if (!lower.includes("boundary") && !lower.includes("limit") && !lower.includes("max") && !lower.includes("min") && !matched.has("boundary")) {
+    matched.set("boundary", "Consider boundary values for relevant fields.");
+  }
+
+  const suggestions = Array.from(matched.values());
+  return { suggestions, score: suggestions.length };
+}
diff --git a/src/types.ts b/src/types.ts
index eb40c24..0dec269 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -96,3 +96,23 @@ export interface TestEachOptions {
 
 /** A single test.each row: [label, input, expected]. */
 export type TestEachRow = [string, unknown, boolean];
+
+// Coverage
+export interface CoverageMapping {
+  requirement: string;
+  matchedTests: string[];
+  covered: boolean;
+}
+
+export interface CoverageResult {
+  covered: string[];
+  uncovered: string[];
+  coveragePercent: number;
+  mapping: CoverageMapping[];
+}
+
+// Suggestions
+export interface SuggestionResult {
+  suggestions: string[];
+  score: number;
+}