diff --git a/apps/web/src/hooks/useDebouncedValue.test.ts b/apps/web/src/hooks/useDebouncedValue.test.ts
new file mode 100644
index 0000000..713e9dc
--- /dev/null
+++ b/apps/web/src/hooks/useDebouncedValue.test.ts
@@ -0,0 +1,78 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
+import { renderHook, act } from '@testing-library/react'
+import { useDebouncedValue } from './useDebouncedValue'
+
+describe('useDebouncedValue', () => {
+  beforeEach(() => {
+    vi.useFakeTimers()
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+  })
+
+  it('returns initial value immediately', () => {
+    const { result } = renderHook(() => useDebouncedValue('hello'))
+    expect(result.current).toBe('hello')
+  })
+
+  it('debounces value updates', () => {
+    const { result, rerender } = renderHook(
+      ({ value }) => useDebouncedValue(value, 300),
+      { initialProps: { value: 'a' } },
+    )
+
+    expect(result.current).toBe('a')
+
+    rerender({ value: 'b' })
+    expect(result.current).toBe('a')
+
+    act(() => { vi.advanceTimersByTime(299) })
+    expect(result.current).toBe('a')
+
+    act(() => { vi.advanceTimersByTime(1) })
+    expect(result.current).toBe('b')
+  })
+
+  it('resets timer on rapid updates', () => {
+    const { result, rerender } = renderHook(
+      ({ value }) => useDebouncedValue(value, 200),
+      { initialProps: { value: 'a' } },
+    )
+
+    rerender({ value: 'b' })
+    act(() => { vi.advanceTimersByTime(100) })
+
+    rerender({ value: 'c' })
+    act(() => { vi.advanceTimersByTime(100) })
+    expect(result.current).toBe('a')
+
+    act(() => { vi.advanceTimersByTime(100) })
+    expect(result.current).toBe('c')
+  })
+
+  it('uses custom delay', () => {
+    const { result, rerender } = renderHook(
+      ({ value }) => useDebouncedValue(value, 500),
+      { initialProps: { value: 'x' } },
+    )
+
+    rerender({ value: 'y' })
+    act(() => { vi.advanceTimersByTime(499) })
+    expect(result.current).toBe('x')
+
+    act(() => { vi.advanceTimersByTime(1) })
+    expect(result.current).toBe('y')
+  })
+
+  it('works with numeric values', () => {
+    const { result, rerender } = renderHook(
+      ({ value }) => useDebouncedValue(value, 100),
+      { initialProps: { value: 0 } },
+    )
+
+    rerender({ value: 42 })
+    act(() => { vi.advanceTimersByTime(100) })
+    expect(result.current).toBe(42)
+  })
+})
diff --git a/apps/web/src/utils/exprEvaluator.test.ts b/apps/web/src/utils/exprEvaluator.test.ts
new file mode 100644
index 0000000..9a52a5d
--- /dev/null
+++ b/apps/web/src/utils/exprEvaluator.test.ts
@@ -0,0 +1,138 @@
+import { describe, it, expect } from 'vitest'
+import { parseExpr, evaluateExpr, evaluateVisibleWhen } from './exprEvaluator'
+
+describe('parseExpr', () => {
+  it('parses equality expression', () => {
+    const ast = parseExpr("status == 'active'")
+    expect(ast).toEqual({
+      type: 'eq',
+      field: 'status',
+      value: 'active',
+    })
+  })
+
+  it('parses inequality expression', () => {
+    const ast = parseExpr("type != 'internal'")
+    expect(ast).toEqual({
+      type: 'neq',
+      field: 'type',
+      value: 'internal',
+    })
+  })
+
+  it('parses AND expression', () => {
+    const ast = parseExpr("status == 'active' AND role == 'admin'")
+    expect(ast).toEqual({
+      type: 'and',
+      left: { type: 'eq', field: 'status', value: 'active' },
+      right: { type: 'eq', field: 'role', value: 'admin' },
+    })
+  })
+
+  it('parses OR expression', () => {
+    const ast = parseExpr("status == 'active' OR status == 'pending'")
+    expect(ast).toEqual({
+      type: 'or',
+      left: { type: 'eq', field: 'status', value: 'active' },
+      right: { type: 'eq', field: 'status', value: 'pending' },
+    })
+  })
+
+  it('parses NOT expression', () => {
+    const ast = parseExpr("NOT status == 'deleted'")
+    expect(ast).toEqual({
+      type: 'not',
+      operand: { type: 'eq', field: 'status', value: 'deleted' },
+    })
+  })
+
+  it('parses parenthesized expression', () => {
+    const ast = parseExpr("(status == 'a' OR status == 'b') AND role == 'admin'")
+    expect(ast?.type).toBe('and')
+    expect(ast?.left?.type).toBe('or')
+  })
+
+  it('returns null for empty input', () => {
+    expect(parseExpr('')).toBeNull()
+  })
+
+  it('parses && and || operators', () => {
+    const ast = parseExpr("a == '1' && b == '2' || c == '3'")
+    expect(ast).toBeDefined()
+    expect(ast?.type).toBe('or')
+  })
+})
+
+describe('evaluateExpr', () => {
+  it('evaluates equality true', () => {
+    const ast = parseExpr("status == 'active'")!
+    expect(evaluateExpr(ast, { status: 'active' })).toBe(true)
+  })
+
+  it('evaluates equality false', () => {
+    const ast = parseExpr("status == 'active'")!
+    expect(evaluateExpr(ast, { status: 'inactive' })).toBe(false)
+  })
+
+  it('evaluates inequality', () => {
+    const ast = parseExpr("status != 'deleted'")!
+    expect(evaluateExpr(ast, { status: 'active' })).toBe(true)
+    expect(evaluateExpr(ast, { status: 'deleted' })).toBe(false)
+  })
+
+  it('evaluates AND', () => {
+    const ast = parseExpr("a == '1' AND b == '2'")!
+    expect(evaluateExpr(ast, { a: '1', b: '2' })).toBe(true)
+    expect(evaluateExpr(ast, { a: '1', b: '3' })).toBe(false)
+    expect(evaluateExpr(ast, { a: '0', b: '2' })).toBe(false)
+  })
+
+  it('evaluates OR', () => {
+    const ast = parseExpr("a == '1' OR b == '2'")!
+    expect(evaluateExpr(ast, { a: '1', b: 'x' })).toBe(true)
+    expect(evaluateExpr(ast, { a: 'x', b: '2' })).toBe(true)
+    expect(evaluateExpr(ast, { a: 'x', b: 'x' })).toBe(false)
+  })
+
+  it('evaluates NOT', () => {
+    const ast = parseExpr("NOT a == '1'")!
+    expect(evaluateExpr(ast, { a: '1' })).toBe(false)
+    expect(evaluateExpr(ast, { a: '2' })).toBe(true)
+  })
+
+  it('handles missing field as empty string', () => {
+    const ast = parseExpr("status == ''")!
+    expect(evaluateExpr(ast, {})).toBe(true)
+  })
+
+  it('converts non-string values to string', () => {
+    const ast = parseExpr("count == '5'")!
+    expect(evaluateExpr(ast, { count: 5 })).toBe(true)
+  })
+})
+
+describe('evaluateVisibleWhen', () => {
+  it('returns true for undefined expression', () => {
+    expect(evaluateVisibleWhen(undefined, {})).toBe(true)
+  })
+
+  it('returns true for empty string expression', () => {
+    expect(evaluateVisibleWhen('', {})).toBe(true)
+  })
+
+  it('evaluates complex expression', () => {
+    expect(
+      evaluateVisibleWhen("type == 'doctor' AND status == 'active'", {
+        type: 'doctor',
+        status: 'active',
+      }),
+    ).toBe(true)
+
+    expect(
+      evaluateVisibleWhen("type == 'doctor' AND status == 'active'", {
+        type: 'doctor',
+        status: 'inactive',
+      }),
+    ).toBe(false)
+  })
+})