diff --git a/dashboard/habits.html b/dashboard/habits.html
index cba9669..ed833a6 100644
--- a/dashboard/habits.html
+++ b/dashboard/habits.html
@@ -1696,9 +1696,29 @@
             if (content.classList.contains('visible')) {
                 content.classList.remove('visible');
                 chevron.classList.remove('expanded');
+                // Save collapsed state to localStorage
+                localStorage.setItem('habits-stats-collapsed', 'true');
             } else {
                 content.classList.add('visible');
                 chevron.classList.add('expanded');
+                // Save expanded state to localStorage
+                localStorage.setItem('habits-stats-collapsed', 'false');
+            }
+        }
+        
+        function restoreWeeklySummaryState() {
+            const content = document.getElementById('weeklySummaryContent');
+            const chevron = document.getElementById('weeklySummaryChevron');
+            const isCollapsed = localStorage.getItem('habits-stats-collapsed');
+            
+            // Default is collapsed (isCollapsed === null means first visit)
+            // Only expand if explicitly set to 'false'
+            if (isCollapsed === 'false') {
+                content.classList.add('visible');
+                chevron.classList.add('expanded');
+            } else {
+                content.classList.remove('visible');
+                chevron.classList.remove('expanded');
             }
         }
         
@@ -2452,6 +2472,9 @@
             }
         });
         
+        // Restore collapsed/expanded state from localStorage
+        restoreWeeklySummaryState();
+        
         loadHabits();
     </script>
 </body>
diff --git a/dashboard/tests/test_habits_frontend.py b/dashboard/tests/test_habits_frontend.py
index 9e42986..4ce2d50 100644
--- a/dashboard/tests/test_habits_frontend.py
+++ b/dashboard/tests/test_habits_frontend.py
@@ -2,6 +2,7 @@
 Test suite for Habits frontend page structure and navigation
 Story US-002: Frontend - Compact habit cards (~100px height)
 Story US-003: Frontend - Check/uncheck toggle behavior
+Story US-005: Frontend - Stats section collapse with chevron
 Story US-006: Frontend - Page structure, layout, and navigation link
 Story US-007: Frontend - Habit card component
 Story US-008: Frontend - Create habit modal with all options
@@ -1752,9 +1753,23 @@ def run_all_tests():
         test_render_habits_uses_search,
         test_event_listeners_initialized,
         test_typecheck_us004,
+        # US-005 tests (Stats section collapse)
+        test_stats_section_collapsed_by_default,
+        test_stats_header_clickable_with_chevron,
+        test_toggle_function_exists,
+        test_chevron_rotates_on_expand,
+        test_content_displays_when_visible,
+        test_localstorage_save_on_toggle,
+        test_restore_function_exists,
+        test_restore_expands_when_false,
+        test_restore_collapses_by_default,
+        test_restore_called_on_page_load,
+        test_css_transition_300ms,
+        test_height_constraint_collapsed,
+        test_typecheck_us005,
     ]
     
-    print(f"\nRunning {len(tests)} frontend tests for US-002, US-003, US-006 through US-014...\n")
+    print(f"\nRunning {len(tests)} frontend tests for US-002, US-003, US-005, US-006 through US-014...\n")
     
     failed = []
     for test in tests:
@@ -2258,5 +2273,260 @@ def test_typecheck_us004():
     assert result.returncode == 0, f"Typecheck failed: {result.stderr}"
     print("✓ Test 137: Typecheck passes")
 
+# ========== US-005 Tests: Stats section collapse with chevron ==========
+
+def test_stats_section_collapsed_by_default():
+    """Test 138: Stats section (weekly summary) starts collapsed by default"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check that weekly-summary-content does NOT have 'visible' class by default in HTML
+    assert '<div class="weekly-summary-content" id="weeklySummaryContent">' in content or \
+           '<div class="weekly-summary-content"' in content, \
+        "weekly-summary-content should not have 'visible' class in HTML"
+    
+    # Check CSS: content should be display:none when not visible
+    assert '.weekly-summary-content {' in content, "Should have weekly-summary-content CSS"
+    assert 'display: none' in content, "Content should be display:none by default"
+    
+    print("✓ Test 138: Stats section starts collapsed (display:none)")
+
+def test_stats_header_clickable_with_chevron():
+    """Test 139: Stats header is clickable and has chevron icon"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check header has onclick handler
+    assert 'onclick="toggleWeeklySummary()"' in content, \
+        "Header should have onclick='toggleWeeklySummary()'"
+    
+    # Check for chevron icon
+    assert 'weekly-summary-chevron' in content, "Should have chevron element"
+    assert 'data-lucide="chevron-down"' in content, "Should use Lucide chevron-down icon"
+    
+    # Check header is styled as clickable
+    assert 'cursor: pointer' in content, "Header should have cursor:pointer"
+    
+    print("✓ Test 139: Stats header is clickable with chevron icon")
+
+def test_toggle_function_exists():
+    """Test 140: toggleWeeklySummary function exists and toggles visibility"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check function exists
+    assert 'function toggleWeeklySummary()' in content, \
+        "toggleWeeklySummary function should be defined"
+    
+    # Find function body
+    func_start = content.find('function toggleWeeklySummary()')
+    func_end = content.find('\n        }', func_start + 1000)
+    func_body = content[func_start:func_end]
+    
+    # Check it toggles visibility class
+    assert 'classList.contains(\'visible\')' in func_body, \
+        "Should check if content has 'visible' class"
+    assert 'classList.remove(\'visible\')' in func_body, \
+        "Should remove 'visible' class when collapsing"
+    assert 'classList.add(\'visible\')' in func_body, \
+        "Should add 'visible' class when expanding"
+    
+    # Check it toggles chevron class
+    assert 'classList.remove(\'expanded\')' in func_body, \
+        "Should remove 'expanded' class from chevron when collapsing"
+    assert 'classList.add(\'expanded\')' in func_body, \
+        "Should add 'expanded' class to chevron when expanding"
+    
+    print("✓ Test 140: toggleWeeklySummary toggles visible and expanded classes")
+
+def test_chevron_rotates_on_expand():
+    """Test 141: Chevron rotates 180deg when expanded"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check for chevron rotation CSS
+    assert '.weekly-summary-chevron.expanded' in content, \
+        "Should have .expanded class styles for chevron"
+    assert 'transform: rotate(180deg)' in content, \
+        "Chevron should rotate 180deg when expanded"
+    
+    # Check for transition
+    assert 'transition:' in content.lower(), "Chevron should have transition"
+    
+    print("✓ Test 141: Chevron rotates 180deg when expanded")
+
+def test_content_displays_when_visible():
+    """Test 142: Content displays (display:block) when visible class is added"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check for .visible class CSS
+    assert '.weekly-summary-content.visible' in content, \
+        "Should have CSS for .visible class"
+    assert 'display: block' in content, \
+        "Content should be display:block when visible"
+    
+    print("✓ Test 142: Content displays when visible class is added")
+
+def test_localstorage_save_on_toggle():
+    """Test 143: toggleWeeklySummary saves state to localStorage"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Find toggleWeeklySummary function
+    func_start = content.find('function toggleWeeklySummary()')
+    func_end = content.find('\n        }', func_start + 1500)
+    func_body = content[func_start:func_end]
+    
+    # Check it saves to localStorage
+    assert 'localStorage.setItem' in func_body, \
+        "Should save state to localStorage"
+    assert "'habits-stats-collapsed'" in func_body or '"habits-stats-collapsed"' in func_body, \
+        "Should use 'habits-stats-collapsed' key"
+    assert "'true'" in func_body or '"true"' in func_body, \
+        "Should save 'true' for collapsed state"
+    assert "'false'" in func_body or '"false"' in func_body, \
+        "Should save 'false' for expanded state"
+    
+    print("✓ Test 143: toggleWeeklySummary saves state to localStorage")
+
+def test_restore_function_exists():
+    """Test 144: restoreWeeklySummaryState function exists and loads from localStorage"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check function exists
+    assert 'function restoreWeeklySummaryState()' in content, \
+        "restoreWeeklySummaryState function should be defined"
+    
+    # Find function body
+    func_start = content.find('function restoreWeeklySummaryState()')
+    func_end = content.find('\n        }', func_start + 1000)
+    func_body = content[func_start:func_end]
+    
+    # Check it loads from localStorage
+    assert 'localStorage.getItem' in func_body, \
+        "Should load state from localStorage"
+    assert "'habits-stats-collapsed'" in func_body or '"habits-stats-collapsed"' in func_body, \
+        "Should use 'habits-stats-collapsed' key"
+    
+    print("✓ Test 144: restoreWeeklySummaryState loads from localStorage")
+
+def test_restore_expands_when_false():
+    """Test 145: restoreWeeklySummaryState expands when localStorage is 'false'"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Find restore function
+    func_start = content.find('function restoreWeeklySummaryState()')
+    func_end = content.find('\n        }', func_start + 1000)
+    func_body = content[func_start:func_end]
+    
+    # Check it expands when isCollapsed === 'false'
+    assert "isCollapsed === 'false'" in func_body or 'isCollapsed==="false"' in func_body or \
+           "isCollapsed === \"false\"" in func_body, \
+        "Should check if isCollapsed is 'false'"
+    assert 'classList.add(\'visible\')' in func_body, \
+        "Should add 'visible' class when expanding"
+    assert 'classList.add(\'expanded\')' in func_body, \
+        "Should add 'expanded' class to chevron when expanding"
+    
+    print("✓ Test 145: restoreWeeklySummaryState expands when localStorage is 'false'")
+
+def test_restore_collapses_by_default():
+    """Test 146: restoreWeeklySummaryState keeps collapsed when localStorage is null or 'true'"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Find restore function
+    func_start = content.find('function restoreWeeklySummaryState()')
+    func_end = content.find('\n        }', func_start + 1000)
+    func_body = content[func_start:func_end]
+    
+    # Check it handles null/true cases (else branch or explicit check)
+    assert 'else' in func_body, "Should have else branch for collapsed state"
+    assert 'classList.remove(\'visible\')' in func_body, \
+        "Should remove 'visible' class for collapsed state"
+    assert 'classList.remove(\'expanded\')' in func_body, \
+        "Should remove 'expanded' class from chevron for collapsed state"
+    
+    print("✓ Test 146: restoreWeeklySummaryState keeps collapsed by default")
+
+def test_restore_called_on_page_load():
+    """Test 147: restoreWeeklySummaryState is called on page load"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check that restore function is called in initialization section
+    # It should be called before or near loadHabits()
+    init_section = content[-3000:]  # Last 3000 chars
+    
+    assert 'restoreWeeklySummaryState()' in init_section, \
+        "Should call restoreWeeklySummaryState() on page load"
+    
+    # Check it's called before loadHabits (or at least in the init section)
+    restore_pos = init_section.find('restoreWeeklySummaryState()')
+    load_pos = init_section.find('loadHabits()')
+    assert restore_pos < load_pos, \
+        "restoreWeeklySummaryState should be called before loadHabits"
+    
+    print("✓ Test 147: restoreWeeklySummaryState called on page load")
+
+def test_css_transition_300ms():
+    """Test 148: CSS uses 300ms ease transition for animations"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Find weekly-summary CSS sections
+    chevron_css_start = content.find('.weekly-summary-chevron')
+    chevron_css_end = content.find('}', chevron_css_start)
+    chevron_css = content[chevron_css_start:chevron_css_end]
+    
+    # Check for transition
+    assert 'transition:' in chevron_css.lower(), \
+        "Chevron should have transition"
+    
+    # The transition should be in the base CSS (using var(--transition-base) or explicit)
+    # var(--transition-base) is typically 300ms ease from common.css
+    assert 'var(--transition-base)' in chevron_css or '0.3s' in chevron_css or '300ms' in chevron_css, \
+        "Should use 300ms transition (or --transition-base variable)"
+    
+    print("✓ Test 148: CSS uses transition for smooth animation")
+
+def test_height_constraint_collapsed():
+    """Test 149: Collapsed state shows minimal height (~30px header only)"""
+    html_path = Path(__file__).parent.parent / 'habits.html'
+    content = html_path.read_text()
+    
+    # Check header padding/height
+    header_css_start = content.find('.weekly-summary-header {')
+    header_css_end = content.find('}', header_css_start)
+    header_css = content[header_css_start:header_css_end]
+    
+    # Header should have padding to create ~30px height
+    assert 'padding:' in header_css.lower(), "Header should have padding"
+    
+    # Content should be hidden (display:none) when not visible
+    content_css_start = content.find('.weekly-summary-content {')
+    content_css_end = content.find('}', content_css_start)
+    content_css = content[content_css_start:content_css_end]
+    
+    assert 'display: none' in content_css or 'display:none' in content_css, \
+        "Content should be display:none when collapsed"
+    
+    print("✓ Test 149: Collapsed state shows minimal height (header only)")
+
+def test_typecheck_us005():
+    """Test 150: Typecheck passes for US-005 changes"""
+    repo_root = Path(__file__).parent.parent.parent
+    result = subprocess.run(
+        ['python3', '-m', 'py_compile', 'dashboard/api.py', 'dashboard/habits_helpers.py'],
+        cwd=repo_root,
+        capture_output=True,
+        text=True
+    )
+    assert result.returncode == 0, f"Typecheck failed: {result.stderr}"
+    print("✓ Test 150: Typecheck passes")
+
 if __name__ == '__main__':
     run_all_tests()