diff --git a/functional_tests/test_per_message_export.py b/functional_tests/test_per_message_export.py
new file mode 100644
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--- /dev/null
+++ b/functional_tests/test_per_message_export.py
@@ -0,0 +1,309 @@
+#!/usr/bin/env python3
+# test_per_message_export.py
+"""
+Functional tests for the per-message export feature (Markdown client-side
+equivalent + Word backend).
+Version: 0.239.008
+Implemented in: 0.239.008
+
+Covers:
+ - Happy path: Word document built successfully from a valid message.
+ - Markdown export logic: correct header, timestamp and content rendered.
+ - Auth failure: unauthenticated caller receives 401.
+ - Ownership failure: caller who does not own the conversation receives 403.
+"""
+
+import sys
+import os
+import io
+
+sys.path.insert(
+    0,
+    os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'application', 'single_app')
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers – replicate key logic from route_backend_conversation_export.py
+# so the tests run without a live Flask + Cosmos DB environment.
+# ---------------------------------------------------------------------------
+
+def _normalize_content(content):
+    """Replicate _normalize_content from route_backend_conversation_export."""
+    if isinstance(content, str):
+        return content
+    if isinstance(content, list):
+        parts = []
+        for item in content:
+            if isinstance(item, dict):
+                if item.get('type') == 'text':
+                    parts.append(item.get('text', ''))
+                elif item.get('type') == 'image_url':
+                    parts.append('[Image]')
+                else:
+                    parts.append(str(item))
+            else:
+                parts.append(str(item))
+        return '\n'.join(parts)
+    if isinstance(content, dict):
+        if content.get('type') == 'text':
+            return content.get('text', '')
+        return str(content)
+    return str(content) if content else ''
+
+
+def _verify_ownership(conversation, requesting_user_id):
+    """Return (ok, status_code, error_msg)."""
+    if conversation is None:
+        return False, 404, 'Conversation not found'
+    if conversation.get('user_id') != requesting_user_id:
+        return False, 403, 'Access denied'
+    return True, 200, None
+
+
+def _check_auth(user_id):
+    """Simulate the authentication guard at the start of the endpoint."""
+    if not user_id:
+        return False, 401, 'User not authenticated'
+    return True, 200, None
+
+
+def _build_markdown_export(role, content, sender, timestamp):
+    """Replicate the client-side Markdown export logic from chat-message-export.js."""
+    lines = []
+    lines.append(f"### {sender}")
+    if timestamp:
+        lines.append(f"*{timestamp}*")
+    lines.append('')
+    lines.append(content)
+    lines.append('')
+    return '\n'.join(lines)
+
+
+# ---------------------------------------------------------------------------
+# Tests
+# ---------------------------------------------------------------------------
+
+def test_happy_path_word_export():
+    """Happy path: Word document is built without error for a valid message."""
+    print("🔍 Testing happy path – Word document generation...")
+
+    try:
+        from docx import Document as DocxDocument
+        from docx.shared import Pt
+    except ImportError as exc:
+        print(f"  ⚠️  python-docx not installed, skipping Word generation check: {exc}")
+        print("✅ test_happy_path_word_export skipped (dependency missing)")
+        return True
+
+    # Arrange
+    requesting_user_id = 'user-alice'
+    conversation = {'id': 'conv-001', 'user_id': 'user-alice'}
+    message = {
+        'id': 'msg-001',
+        'role': 'assistant',
+        'content': '**Hello**, world!\n\nThis is a test.',
+        'timestamp': '2025-06-01T10:00:00Z',
+        'citations': [
+            {'title': 'Reference Doc', 'url': 'https://example.com/ref'}
+        ]
+    }
+
+    # Auth check
+    auth_ok, auth_status, auth_err = _check_auth(requesting_user_id)
+    assert auth_ok, f"Auth should pass, got {auth_status}: {auth_err}"
+
+    # Ownership check
+    ok, status, err = _verify_ownership(conversation, requesting_user_id)
+    assert ok, f"Ownership check should pass, got {status}: {err}"
+
+    # Build Word document
+    doc = DocxDocument()
+    doc.add_heading('Message Export', level=1)
+
+    role = message.get('role', 'unknown').capitalize()
+    timestamp = message.get('timestamp', '')
+
+    meta_para = doc.add_paragraph()
+    meta_run = meta_para.add_run(f"Role: {role}")
+    meta_run.bold = True
+    if timestamp:
+        meta_para.add_run(f"    {timestamp}")
+
+    doc.add_paragraph('')
+
+    content = _normalize_content(message.get('content', ''))
+
+    # Add content as a paragraph (simplified – full logic tested in route unit)
+    doc.add_paragraph(content)
+
+    citations = message.get('citations', [])
+    if citations:
+        doc.add_heading('Citations', level=2)
+        for cit in citations:
+            source = cit.get('title') or cit.get('url', 'Unknown')
+            doc.add_paragraph(source, style='List Bullet')
+
+    # Serialise to buffer – if this raises, the test fails
+    buffer = io.BytesIO()
+    doc.save(buffer)
+    buffer.seek(0)
+    docx_bytes = buffer.read()
+
+    assert len(docx_bytes) > 0, "Generated docx should be non-empty"
+
+    # Round-trip verify
+    buffer.seek(0)
+    loaded = DocxDocument(io.BytesIO(docx_bytes))
+    headings = [p.text for p in loaded.paragraphs if p.style.name.startswith('Heading')]
+    assert 'Message Export' in headings, "Document should have 'Message Export' heading"
+
+    print("✅ test_happy_path_word_export passed!")
+    return True
+
+
+def test_happy_path_markdown_export():
+    """Happy path: Markdown file content is correctly formatted."""
+    print("🔍 Testing happy path – Markdown export...")
+
+    role = 'assistant'
+    content = 'Here is a **bold** answer.'
+    sender = 'Assistant'
+    timestamp = '2025-06-01T10:05:00Z'
+
+    markdown = _build_markdown_export(role, content, sender, timestamp)
+
+    assert '### Assistant' in markdown, "Should have role heading"
+    assert f'*{timestamp}*' in markdown, "Should include timestamp"
+    assert content in markdown, "Should include message content"
+    # File should start with the heading line
+    assert markdown.startswith('### Assistant'), "Heading should be first line"
+
+    print("✅ test_happy_path_markdown_export passed!")
+    return True
+
+
+def test_auth_failure_unauthenticated():
+    """Auth failure: an unauthenticated caller (no user_id) should get 401."""
+    print("🔍 Testing auth failure – unauthenticated request...")
+
+    for bad_user_id in (None, '', False):
+        ok, status, err = _check_auth(bad_user_id)
+        assert not ok, f"Auth should fail for user_id={bad_user_id!r}"
+        assert status == 401, f"Expected 401, got {status}"
+        assert err == 'User not authenticated', f"Unexpected error message: {err}"
+
+    print("✅ test_auth_failure_unauthenticated passed!")
+    return True
+
+
+def test_ownership_failure_wrong_user():
+    """Ownership failure: user requesting another user's conversation gets 403."""
+    print("🔍 Testing ownership failure – wrong user...")
+
+    conversation = {'id': 'conv-bob', 'user_id': 'user-bob'}
+    requesting_user = 'user-alice'
+
+    ok, status, err = _verify_ownership(conversation, requesting_user)
+
+    assert not ok, "Ownership check should fail"
+    assert status == 403, f"Expected 403, got {status}"
+    assert err == 'Access denied', f"Unexpected error message: {err}"
+
+    print("✅ test_ownership_failure_wrong_user passed!")
+    return True
+
+
+def test_ownership_failure_missing_conversation():
+    """Ownership failure: conversation not found should return 404."""
+    print("🔍 Testing ownership failure – conversation not found...")
+
+    ok, status, err = _verify_ownership(None, 'user-alice')
+
+    assert not ok, "Ownership check should fail for missing conversation"
+    assert status == 404, f"Expected 404, got {status}"
+    assert err == 'Conversation not found', f"Unexpected error message: {err}"
+
+    print("✅ test_ownership_failure_missing_conversation passed!")
+    return True
+
+
+def test_normalize_content_variants():
+    """Content normalisation handles strings, lists, and dicts correctly."""
+    print("🔍 Testing content normalisation...")
+
+    # Plain string – unchanged
+    assert _normalize_content('hello') == 'hello'
+
+    # List of text parts
+    result = _normalize_content([
+        {'type': 'text', 'text': 'Part 1'},
+        {'type': 'text', 'text': 'Part 2'},
+    ])
+    assert result == 'Part 1\nPart 2', f"Unexpected: {result!r}"
+
+    # Image entry in list
+    result = _normalize_content([
+        {'type': 'text', 'text': 'Before image'},
+        {'type': 'image_url', 'image_url': {'url': 'https://example.com/img.png'}},
+    ])
+    assert '[Image]' in result, "Image entries should render as [Image]"
+
+    # Dict with type=text
+    assert _normalize_content({'type': 'text', 'text': 'Hi'}) == 'Hi'
+
+    # None / empty
+    assert _normalize_content(None) == ''
+    assert _normalize_content('') == ''
+
+    print("✅ test_normalize_content_variants passed!")
+    return True
+
+
+def test_markdown_export_no_timestamp():
+    """Markdown export omits the timestamp line when timestamp is empty."""
+    print("🔍 Testing Markdown export without timestamp...")
+
+    markdown = _build_markdown_export('user', 'Hello!', 'User', '')
+
+    assert '### User' in markdown
+    assert 'Hello!' in markdown
+    # No italicised timestamp line should be present
+    lines = markdown.splitlines()
+    italic_lines = [line for line in lines if line.startswith('*') and line.endswith('*')]
+    assert not italic_lines, f"Should be no timestamp lines, found: {italic_lines}"
+
+    print("✅ test_markdown_export_no_timestamp passed!")
+    return True
+
+
+# ---------------------------------------------------------------------------
+# Runner
+# ---------------------------------------------------------------------------
+
+if __name__ == "__main__":
+    tests = [
+        test_happy_path_word_export,
+        test_happy_path_markdown_export,
+        test_auth_failure_unauthenticated,
+        test_ownership_failure_wrong_user,
+        test_ownership_failure_missing_conversation,
+        test_normalize_content_variants,
+        test_markdown_export_no_timestamp,
+    ]
+    results = []
+
+    for test_fn in tests:
+        print(f"\n🧪 Running {test_fn.__name__}...")
+        try:
+            results.append(test_fn())
+        except Exception as exc:
+            print(f"❌ {test_fn.__name__} failed: {exc}")
+            import traceback
+            traceback.print_exc()
+            results.append(False)
+
+    success = all(results)
+    passed = sum(1 for r in results if r)
+    print(f"\n📊 Results: {passed}/{len(results)} tests passed")
+    sys.exit(0 if success else 1)