diff --git a/.gitignore b/.gitignore
index 3facd9e..5791ae2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,8 +41,8 @@ reaper_config.yaml
 *.log
 
 # Temporary Test Scripts
+#test_*.py
 tmp/
-test_*.py
 test_release.zip
 test_release/
 DiscoReaper
diff --git a/requirements.txt b/requirements.txt
index aba503e..d3d7224 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,4 +8,7 @@ pydantic # Data validation using Python type hints
 lottie # Lottie file manipulation and conversion
 Pillow # Image processing (required for GIF rendering)
 cairosvg # SVG rendering (required for Lottie conversion)
-psutil # System information (CPU, RAM, etc.)
\ No newline at end of file
+psutil # System information (CPU, RAM, etc.)
+pytest # Testing framework
+pytest-asyncio # Async testing for pytest
+pytest-mock # Mocking for pytest
\ No newline at end of file
diff --git a/runtests.sh b/runtests.sh
new file mode 100755
index 0000000..81f1576
--- /dev/null
+++ b/runtests.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+# Convenient script to run the Discord Reaper test suite.
+# Automatically handles VENV activation and PYTHONPATH.
+
+# Change to the project root directory (where the script is located)
+cd "$(dirname "$0")"
+
+# Activate the virtual environment if it exists
+if [ -d "venv" ]; then
+    source venv/bin/activate
+fi
+
+# Set PYTHONPATH to the current directory so src is discoverable
+export PYTHONPATH=.
+
+# Run pytest with any arguments passed to this script, defaulting to tests/
+if [ $# -eq 0 ]; then
+    pytest -v -s -p no:warnings tests/
+else
+    pytest -s "$@"
+fi
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..383ed0f
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,170 @@
+import pytest
+import shutil
+import yaml
+from pathlib import Path
+from unittest.mock import AsyncMock, MagicMock
+from src.core.backup_database import BackupDatabase
+from src.core.configuration import AppConfig
+
+LOG_FILE = (Path(__file__).parent.parent / ".reaper_tests.log").resolve()
+
+def _log(msg: str):
+    """Write a message to the shared test log file."""
+    with open(LOG_FILE, "a") as f:
+        f.write(f"{msg}\n")
+
+@pytest.fixture
+def log():
+    """Fixture to provide the logging function to tests."""
+    return _log
+
+def pytest_configure(config):
+    """Register global warning filters and marks."""
+    # Register marks if needed
+    config.addinivalue_line("markers", "asyncio: mark test as asyncio")
+    
+    # Silence benign async mock and ResourceWarnings globally
+    config.addinivalue_line("filterwarnings", "ignore::RuntimeWarning")
+    config.addinivalue_line("filterwarnings", "ignore::ResourceWarning")
+
+def pytest_sessionstart(session):
+    """Clear the log file at the beginning of the test session."""
+    with open(LOG_FILE, "w") as f:
+        f.write("--- Reaper Test Session Started ---\n")
+
+def pytest_report_header(config):
+    """Print data source status to the console header."""
+    test_data_dir = (Path(__file__).parent.parent / "ReaperFiles-AutoTest").resolve()
+    if test_data_dir.exists():
+        return f"[DATA_SOURCE] Automated Test Directory: FOUND ({test_data_dir.name})"
+    else:
+        return "[DATA_SOURCE] Automated Test Directory: NOT FOUND (Falling back to MOCKS)"
+
+@pytest.hookimpl(tryfirst=True, hookwrapper=True)
+def pytest_runtest_makereport(item, call):
+    """Hook to catch test results and log them to .reaper_tests.log."""
+    outcome = yield
+    rep = outcome.get_result()
+    
+    # We only log on the 'call' phase (the actual test run)
+    if rep.when == "call":
+        status = rep.outcome.upper()
+        _log(f"RESULT: {item.nodeid} -> {status}")
+        if rep.failed:
+            _log(f"--- FAILURE DETAILS for {item.name} ---\n{rep.longreprtext}\n---------------------")
+    elif not rep.passed:
+        # Catch setup/teardown failures
+        _log(f"ERROR in {item.nodeid} [{rep.when}]: {rep.outcome.upper()}")
+        if rep.failed:
+            _log(f"--- ERROR DETAILS ---\n{rep.longreprtext}\n---------------------")
+
+def pytest_warning_recorded(warning_message, when, nodeid, location):
+    """Hook to catch and log warnings to .reaper_tests.log."""
+    msg = f"WARNING: {warning_message.message}"
+    if nodeid:
+        msg = f"WARNING in {nodeid} [{when}]: {warning_message.message}"
+    _log(msg)
+
+@pytest.fixture
+def test_data_dir():
+    return (Path(__file__).parent.parent / "ReaperFiles-AutoTest").resolve()
+
+@pytest.fixture
+def reaper_config(test_data_dir):
+    config_path = test_data_dir / "reaper_config.yaml"
+    if config_path.exists():
+        with open(config_path, "r") as f:
+            data = yaml.safe_load(f)
+        return data
+    # Fallback mock config
+    return {
+        "discord_bot_token": "mock_discord_token",
+        "discord_server_id": "123456789012345678",
+        "tool_mode": "backup_transfer",
+        "target_platform": "fluxer",
+        "fluxer_bot_token": "mock_fluxer_token",
+        "fluxer_server_id": "987654321098765432",
+        "stoat_bot_token": "mock_stoat_token",
+        "stoat_server_id": "MOCK_STOAT_COMMUNITY",
+        "anonymize_users": False,
+        "log_level": "DEBUG"
+    }
+
+@pytest.fixture
+def temp_db(test_data_dir, tmp_path, reaper_config):
+    # If the real test data exists, use it
+    if test_data_dir.exists():
+        target_id = reaper_config.get("fluxer_server_id") if reaper_config.get("target_platform") == "fluxer" else reaper_config.get("stoat_server_id")
+        db_files = list(test_data_dir.glob(f"*-{target_id}.db"))
+        if not db_files:
+            db_files = list(test_data_dir.glob("*.db"))
+            
+        if db_files:
+            original_db = db_files[0]
+            temp_db_path = tmp_path / "test_migration.db"
+            print(f"[DATA_SOURCE] USE_SAMPLE_DB: {original_db.name}")
+            _log(f"[DATA_SOURCE] USE_SAMPLE_DB: {original_db.name}")
+            shutil.copy(original_db, temp_db_path)
+            return temp_db_path
+
+    # Fallback: Create an empty mock database with the required schema
+    temp_db_path = tmp_path / "mock_migration.db"
+    print("[DATA_SOURCE] USE_MOCK_DB: Fallback to empty schema")
+    _log("[DATA_SOURCE] USE_MOCK_DB: Fallback to empty schema")
+    db = BackupDatabase(temp_db_path)
+    # The BackupDatabase constructor already initializes the schema
+    return temp_db_path
+
+@pytest.fixture
+def backup_db(temp_db):
+    db = BackupDatabase(temp_db)
+    yield db
+    # No explicit close needed for now as it's a persistent connection
+
+@pytest.fixture
+def backup_reader(test_data_dir, reaper_config, tmp_path):
+    sid = reaper_config.get("discord_server_id")
+    backup_path = test_data_dir / f"DISCORD_BACKUP-{sid}"
+    
+    if not test_data_dir.exists() or not backup_path.exists():
+        # Fallback: create mock backup structure
+        mock_path = tmp_path / f"DISCORD_BACKUP-{sid}"
+        print(f"[DATA_SOURCE] USE_MOCK_BACKUP: {mock_path.name}")
+        _log(f"[DATA_SOURCE] USE_MOCK_BACKUP: {mock_path.name}")
+        mock_path.mkdir(parents=True, exist_ok=True)
+        db_path = mock_path / "backup.db"
+        db = BackupDatabase(db_path)
+        # Populate with minimal mock data for BackupReader to work
+        db._conn.execute("INSERT OR IGNORE INTO guild_profile (id, name) VALUES (?, ?)", (int(sid), "Mock Guild"))
+        db._conn.execute("INSERT OR IGNORE INTO channels (id, name, type) VALUES (?, ?, ?)", (123, "mock-channel", 0))
+        db._conn.commit()
+        from src.core.backup_reader import BackupReader
+        return BackupReader(mock_path)
+        
+    print(f"[DATA_SOURCE] USE_SAMPLE_BACKUP: {backup_path.name}")
+    _log(f"[DATA_SOURCE] USE_SAMPLE_BACKUP: {backup_path.name}")
+    from src.core.backup_reader import BackupReader
+    return BackupReader(backup_path)
+
+@pytest.fixture
+def mock_discord_reader():
+    reader = MagicMock()
+    reader.guild = MagicMock()
+    reader.fetch_message_history = AsyncMock()
+    reader.download_attachment = AsyncMock(return_value=b"fake_data")
+    reader.download_sticker = AsyncMock(return_value=b"fake_sticker_data")
+    return reader
+
+@pytest.fixture
+def mock_fluxer_writer():
+    writer = MagicMock()
+    writer.send_message = AsyncMock(return_value="fluxer_msg_123")
+    writer.send_marker = AsyncMock()
+    return writer
+
+@pytest.fixture
+def mock_stoat_writer():
+    writer = MagicMock()
+    writer.send_message = AsyncMock(return_value="stoat_msg_123")
+    writer.send_marker = AsyncMock()
+    return writer
diff --git a/tests/test_database.py b/tests/test_database.py
new file mode 100644
index 0000000..c70a880
--- /dev/null
+++ b/tests/test_database.py
@@ -0,0 +1,139 @@
+import pytest
+from src.core.backup_database import BackupDatabase
+
+
+@pytest.fixture
+def db():
+    from tests.conftest import _log
+    msg = "[DATA_SOURCE] UNIT_TEST: Using in-memory database"
+    print(msg)
+    _log(msg)
+    return BackupDatabase(":memory:")
+
+
+def test_db_initialization(db):
+    res = db._conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name='guild_profile'"
+    ).fetchone()
+    assert res is not None
+    assert res["name"] == "guild_profile"
+
+
+def test_save_get_guild_profile(db):
+    profile = {
+        "id": "123456789",
+        "name": "Test Server",
+        "description": "Testing",
+        "owner_id": "987654321",
+        "ignore_channels": ["111", "222"],
+    }
+    db.set_guild_profile(profile)
+    got = db.get_guild_profile()
+    assert got["name"] == "Test Server"
+    assert got["id"] == 123456789
+    assert got["ignore_channels"] == ["111", "222"]
+
+
+def test_save_get_roles(db):
+    roles = [
+        {"id": "1", "name": "Admin", "color": 0xFF0000, "position": 1, "permissions": 8, "hoist": True, "mentionable": True},
+        {"id": "2", "name": "User",  "color": 0x0000FF, "position": 2, "permissions": 0, "hoist": False, "mentionable": False},
+    ]
+    db.save_roles(roles)
+    got = db.get_all_roles()
+    assert len(got) == 2
+    assert {r["name"] for r in got} == {"Admin", "User"}
+
+
+def test_save_get_channels(db):
+    channels = [
+        {"id": 10, "name": "general", "type": 0, "position": 0, "category_id": None,
+         "topic": "Talk", "nsfw": 0, "bitrate": None, "slowmode_delay": None},
+        {"id": 20, "name": "voice", "type": 2, "position": 1, "category_id": None,
+         "topic": None, "nsfw": 0, "bitrate": 64000, "slowmode_delay": None},
+    ]
+    db.save_channels(channels)
+    got = db.get_all_channels()
+    assert len(got) == 2
+    assert {c["name"] for c in got} == {"general", "voice"}
+
+
+def test_save_messages_and_attachments(db):
+    messages = [
+        {
+            "id": 101, "channel_id": 10, "author_id": 999, "content": "Hello",
+            "timestamp": "2023-01-01T00:00:00Z", "type": 0,
+            "message_reference": None, "is_pinned": 0, "extra_data": None,
+            "attachments": [
+                {"id": 1, "filename": "file.png", "size": 100,
+                 "url": "http://cdn.test/file.png", "content_type": "image/png", "local_hash": "abc"}
+            ],
+        }
+    ]
+    db.save_messages_batch(messages)
+    msg = db._conn.execute("SELECT content FROM messages WHERE id=101").fetchone()
+    assert msg["content"] == "Hello"
+    att = db._conn.execute("SELECT filename FROM attachments WHERE message_id=101").fetchone()
+    assert att["filename"] == "file.png"
+
+
+def test_get_last_message_id(db):
+    msgs = [
+        {"id": 200, "channel_id": 10, "author_id": 1, "content": "a",
+         "timestamp": "2023-01-01T00:00:00Z", "type": 0,
+         "message_reference": None, "is_pinned": 0, "extra_data": None},
+        {"id": 201, "channel_id": 10, "author_id": 1, "content": "b",
+         "timestamp": "2023-01-01T00:01:00Z", "type": 0,
+         "message_reference": None, "is_pinned": 0, "extra_data": None},
+    ]
+    db.save_messages_batch(msgs)
+    assert db.get_last_message_id("10") == 201
+
+
+def test_stats_by_channel(db):
+    msgs = [
+        {"id": 101, "channel_id": 10, "author_id": 1, "content": "Hi",
+         "timestamp": "2023-01-01T00:00:00Z", "type": 0,
+         "message_reference": None, "is_pinned": 0, "extra_data": None},
+        {"id": 102, "channel_id": 10, "author_id": 1, "content": "Bye",
+         "timestamp": "2023-01-01T00:01:00Z", "type": 0,
+         "message_reference": None, "is_pinned": 0, "extra_data": None},
+    ]
+    db.save_messages_batch(msgs)
+    stats = db.get_stats_by_channel()
+    assert stats[10]["message_count"] == 2
+
+
+def test_save_threads(db):
+    threads = [
+        {"id": 300, "name": "thread-1", "type": 11, "parent_id": 10,
+         "message_count": 5, "member_count": 2, "archived": 0,
+         "archive_timestamp": None, "auto_archive_duration": 1440,
+         "locked": 0, "applied_tags": None},
+    ]
+    db.save_threads(threads)
+    got = db.get_threads_by_parent("10")
+    assert len(got) == 1
+    assert got[0]["name"] == "thread-1"
+
+
+def test_media_pool(db):
+    db.add_media_to_pool("hash123", "/path/file.png", 512, "image/png", "http://cdn.test/file.png")
+    db._conn.commit()
+    entry = db.get_media_by_hash("hash123")
+    assert entry is not None
+    assert entry["local_path"] == "/path/file.png"
+
+
+def test_get_messages_paged_after_id(db):
+    msgs = [
+        {"id": i, "channel_id": 10, "author_id": 1, "content": f"msg{i}",
+         "timestamp": f"2023-01-01T00:0{i}:00Z", "type": 0,
+         "message_reference": None, "is_pinned": 0, "extra_data": None}
+        for i in range(5)
+    ]
+    db.save_messages_batch(msgs)
+    page = db.get_messages_paged("10", limit=3, offset=0)
+    assert len(page) == 3
+    page_after = db.get_messages_paged("10", limit=10, after_id="2")
+    assert all(m["id"] > 2 for m in page_after)
diff --git a/tests/test_migration.py b/tests/test_migration.py
new file mode 100644
index 0000000..8a17c50
--- /dev/null
+++ b/tests/test_migration.py
@@ -0,0 +1,138 @@
+import pytest
+from unittest.mock import MagicMock, AsyncMock, patch
+from src.core.base import MigrationContext
+from src.core.configuration import AppConfig
+from src.core.backup_reader import ChannelType
+from src.fluxer.migrate_message import migrate_messages as fluxer_migrate, _process_and_send_message as fluxer_send
+from src.stoat.migrate_message import migrate_messages as stoat_migrate, _process_and_send_message as stoat_send
+
+import yaml
+from pathlib import Path
+
+# --- Platform Detection (Same as e2e_simulation) ---
+def get_platforms():
+    """Determine which platforms to test based on config, or use defaults."""
+    config_path = (Path(__file__).parent.parent / "ReaperFiles-AutoTest/reaper_config.yaml").resolve()
+    if not config_path.exists():
+        return ["fluxer", "stoat"]
+    with open(config_path, "r") as f:
+        data = yaml.safe_load(f)
+    platforms = []
+    if data.get("fluxer_bot_token"): platforms.append("fluxer")
+    if data.get("stoat_bot_token"): platforms.append("stoat")
+    return platforms if platforms else ["fluxer", "stoat"]
+
+# --- Unit Tests (Transformation Logic) ---
+
+@pytest.fixture
+def mock_context(mock_discord_reader, mock_fluxer_writer, mock_stoat_writer):
+    context = MagicMock(spec=MigrationContext)
+    context.discord_reader = mock_discord_reader
+    context.fluxer_writer = mock_fluxer_writer
+    context.stoat_writer = mock_stoat_writer
+    context.state = MagicMock()
+    context.state.get_user_alias.return_value = "TestAlias"
+    context.state.emoji_map = {}
+    context.state.channel_map = {}
+    context.is_running = True
+    return context
+
+@pytest.fixture
+def mock_message():
+    msg = MagicMock()
+    msg.id = 111
+    msg.author.id = 222
+    msg.author.display_name = "Author"
+    msg.content = "Test content"
+    msg.attachments = []
+    msg.embeds = []
+    msg.stickers = []
+    msg.created_at.timestamp.return_value = 1600000000.0
+    msg.flags.forwarded = False
+    msg.reference = None
+    return msg
+
+@pytest.mark.asyncio
+async def test_migration_transform_fluxer(mock_context, mock_message):
+    stats = {"messages": 0, "attachments": 0}
+    result = await fluxer_send(context=mock_context, msg=mock_message, target_channel_id="c1", stats=stats)
+    assert result == "fluxer_msg_123"
+    assert stats["messages"] == 1
+    assert mock_context.fluxer_writer.send_message.called
+
+@pytest.mark.asyncio
+async def test_migration_transform_stoat(mock_context, mock_message):
+    stats = {"messages": 0, "attachments": 0}
+    result = await stoat_send(context=mock_context, msg=mock_message, target_channel_id="c1", stats=stats)
+    assert result == "stoat_msg_123"
+    assert stats["messages"] == 1
+    assert mock_context.stoat_writer.send_message.called
+
+# --- Integration Tests (Backup Reader) ---
+
+@pytest.mark.asyncio
+async def test_backup_reader_interaction(backup_reader, reaper_config):
+    await backup_reader.start()
+    assert backup_reader.guild is not None
+    # Verify ID from config (or mock default)
+    assert str(backup_reader.guild.id) == reaper_config.get("discord_server_id")
+    
+    channels = await backup_reader.fetch_channels()
+    assert len(channels) > 0
+
+# --- E2E Simulation ---
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("platform", get_platforms())
+async def test_migration_e2e_loop(reaper_config, test_data_dir, tmp_path, platform, request):
+    config = AppConfig(
+        discord_bot_token=reaper_config["discord_bot_token"],
+        discord_server_id=reaper_config["discord_server_id"],
+        target_platform=platform,
+        fluxer_bot_token=reaper_config.get("fluxer_bot_token"),
+        fluxer_server_id=reaper_config.get("fluxer_server_id"),
+        stoat_bot_token=reaper_config.get("stoat_bot_token"),
+        stoat_server_id=reaper_config.get("stoat_server_id"),
+        anonymize_users=reaper_config["anonymize_users"]
+    )
+    
+    if test_data_dir.exists():
+        base_dir = test_data_dir
+        msg = f"[DATA_SOURCE] E2E_SIMULATION: Using sample data from {base_dir.name}"
+    else:
+        base_dir = tmp_path
+        msg = f"[DATA_SOURCE] E2E_SIMULATION: Fallback to mock data in {base_dir}"
+    
+    from tests.conftest import _log
+    print(msg)
+    _log(msg)
+    
+    context = MigrationContext(config, source_mode="backup", base_dir=str(base_dir))
+    
+    mock_writer = request.getfixturevalue(f"mock_{platform}_writer")
+    if platform == "fluxer":
+        context.fluxer_writer = mock_writer
+        migrate_func = fluxer_migrate
+    else:
+        context.stoat_writer = mock_writer
+        migrate_func = stoat_migrate
+        
+    context.is_running = True
+    from src.core.database import MigrationDatabase
+    context.state.db = MigrationDatabase(tmp_path / f"e2e_{platform}.db", platform=platform)
+    
+    await context.discord_reader.start()
+    channels = await context.discord_reader.fetch_channels()
+    text_channels = [c for c in channels if c.type == ChannelType.text]
+    
+    if text_channels:
+        source_channel_id = text_channels[0].id
+        target_channel_id = "999" if platform == "fluxer" else "stoat123"
+        
+        mock_writer.send_message.side_effect = lambda **kwargs: "ok"
+        
+        # Test just the first available channel to keep it fast
+        stats = await migrate_func(context=context, source_channel_id=source_channel_id, target_channel_id=target_channel_id)
+        assert stats["messages"] >= 0
+    
+    await context.discord_reader.close()
diff --git a/tests/test_ui.py b/tests/test_ui.py
new file mode 100644
index 0000000..b69001d
--- /dev/null
+++ b/tests/test_ui.py
@@ -0,0 +1,117 @@
+import pytest
+import asyncio
+from pathlib import Path
+from unittest.mock import MagicMock, AsyncMock, patch
+from textual.app import App
+from src.ui.main_app import ReaperApp, ConfigSelectionScreen, ConfigScreen
+from src.ui.mode_screen import ModeScreen
+from src.core.configuration import AppConfig
+
+import os
+from textual.widgets import ListItem, ListView, Input, Button
+
+
+
+@pytest.fixture
+def mock_configs(tmp_path, log):
+    reaper_dir = tmp_path / "ReaperFiles-TestConfig"
+    reaper_dir.mkdir()
+    (reaper_dir / "reaper_config.yaml").write_text("discord_bot_token: 'fake'\ndiscord_server_id: '123'\ntool_mode: 'backup_only'")
+    
+    old_cwd = os.getcwd()
+    os.chdir(tmp_path)
+    log(f"CWD changed to: {tmp_path}")
+    yield tmp_path
+    os.chdir(old_cwd)
+
+async def wait_for_screen(app, screen_class, timeout=5.0):
+    import time
+    start = time.time()
+    while time.time() - start < timeout:
+        if isinstance(app.screen, screen_class):
+            return True
+        await asyncio.sleep(0.1)
+    return False
+
+@pytest.mark.asyncio
+async def test_ui_minimal_launch(mock_configs, log):
+    """Verify app launch and screen transition to ModeScreen."""
+    log("Running test_ui_minimal_launch")
+    try:
+        # Reverting to AsyncMock to avoid WorkerError. 
+        # RuntimeWarnings are now handled globally in conftest.py.
+        with patch("src.ui.main_app.ConfigSelectionScreen.check_updates", AsyncMock()):
+            app = ReaperApp()
+            async with app.run_test() as pilot:
+                await wait_for_screen(app, ConfigSelectionScreen)
+                await pilot.click(ListItem)
+                await wait_for_screen(app, ModeScreen)
+                assert isinstance(app.screen, ModeScreen)
+                log("test_ui_minimal_launch PASSED")
+    except Exception as e:
+        log(f"test_ui_minimal_launch FAILED: {e}")
+        raise
+
+@pytest.mark.asyncio
+async def test_ui_config_wizard_save(mock_configs, log):
+    """Verify configuration editing and saving."""
+    log("Running test_ui_config_wizard_save")
+    try:
+        with patch("src.ui.main_app.ConfigSelectionScreen.check_updates", AsyncMock()):
+            app = ReaperApp()
+            async with app.run_test() as pilot:
+                await wait_for_screen(app, ConfigSelectionScreen)
+                await pilot.click(ListItem)
+                await wait_for_screen(app, ModeScreen)
+                await pilot.click("#btn_config")
+                await wait_for_screen(app, ConfigScreen)
+                
+                screen = app.screen
+                inp = screen.query_one("#inp_discord_token", Input)
+                inp.value = "new_fake_token"
+                
+                with patch("src.ui.main_app.save_config") as mock_save:
+                    await pilot.click("#btn_save")
+                    await pilot.pause(0.2)
+                    assert mock_save.called
+                    log("test_ui_config_wizard_save PASSED")
+    except Exception as e:
+        log(f"test_ui_config_wizard_save FAILED: {e}")
+        raise
+
+@pytest.mark.asyncio
+async def test_ui_operation_trigger(mock_configs, log):
+    """Verify that an operation can be triggered."""
+    log("Running test_ui_operation_trigger")
+    from src.ui.shuttle_ops import OperationPane
+    from src.ui.modals import ChannelPickerScreen, ProgressScreen
+    try:
+        with patch("src.ui.main_app.ConfigSelectionScreen.check_updates", AsyncMock()):
+            # run_validate is decorated with @work in shuttle_ops.py, so it MUST be a coroutine (AsyncMock)
+            with patch.object(OperationPane, "run_validate", AsyncMock()):
+                app = ReaperApp()
+                async with app.run_test() as pilot:
+                    await wait_for_screen(app, ConfigSelectionScreen)
+                    await pilot.click(ListItem)
+                    await wait_for_screen(app, ModeScreen)
+                    
+                    pane = app.screen.query_one(OperationPane)
+                    pane.tokens_valid = True
+                    pane.src_channels = [{"id": 1, "name": "t"}]
+                    pane.src_cat_map = {None: "D"}
+                    pane.tgt_channels = [{"id": 2, "name": "t"}]
+                    pane.tgt_cat_map = {None: "D"}
+                    pane.all_tgt_channels = pane.tgt_channels
+                    
+                    btn = pane.query_one("#op_backup_msgs", Button)
+                    btn.disabled = False
+                    await pilot.pause(0.2)
+                    btn.focus()
+                    await pilot.press("enter")
+                    
+                    await wait_for_screen(app, (ChannelPickerScreen, ProgressScreen))
+                    assert isinstance(app.screen, (ChannelPickerScreen, ProgressScreen))
+                    log("test_ui_operation_trigger PASSED")
+    except Exception as e:
+        log(f"test_ui_operation_trigger FAILED: {e}")
+        raise
diff --git a/tests/test_utils.py b/tests/test_utils.py
new file mode 100644
index 0000000..18a75c4
--- /dev/null
+++ b/tests/test_utils.py
@@ -0,0 +1,60 @@
+import pytest
+from unittest.mock import MagicMock
+from src.core.utils import parse_snowflake, resolve_discord_links
+
+def test_parse_snowflake_valid():
+    assert parse_snowflake("12345") == 12345
+    assert parse_snowflake(12345) == 12345
+    assert parse_snowflake("  67890  ") == 67890
+
+def test_parse_snowflake_invalid():
+    assert parse_snowflake(None) is None
+    assert parse_snowflake("") is None
+    assert parse_snowflake("none") is None
+    assert parse_snowflake("NULL") is None
+    assert parse_snowflake("not_a_number") is None
+
+def test_resolve_discord_links_no_content():
+    assert resolve_discord_links("", None, "fluxer", "target_id") == ""
+    assert resolve_discord_links(None, None, "fluxer", "target_id") is None
+
+def test_resolve_discord_links_no_mapping():
+    mock_state = MagicMock()
+    mock_state.get_target_channel_id.return_value = None
+    mock_state.get_target_category_id.return_value = None
+    mock_state.find_message_mapping.return_value = (None, None)
+    
+    content = "Check this: https://discord.com/channels/1/2/3"
+    resolved = resolve_discord_links(content, mock_state, "fluxer", "target_server")
+    assert "[`discord-message`](<https://discord.com/channels/1/2/3>)" in resolved
+
+def test_resolve_discord_links_channel_mapping():
+    mock_state = MagicMock()
+    mock_state.get_target_channel_id.return_value = "target_chan_456"
+    mock_state.find_message_mapping.return_value = (None, None)
+    
+    content = "Go to https://discord.com/channels/123/456"
+    
+    # Test Fluxer
+    resolved_fluxer = resolve_discord_links(content, mock_state, "fluxer", "target_server")
+    assert "https://fluxer.app/channels/target_server/target_chan_456" in resolved_fluxer
+    
+    # Test Stoat
+    resolved_stoat = resolve_discord_links(content, mock_state, "stoat", "target_server")
+    assert "https://stoat.chat/server/target_server/channel/target_chan_456" in resolved_stoat
+
+def test_resolve_discord_links_message_mapping():
+    mock_state = MagicMock()
+    mock_state.find_message_mapping.return_value = ("target_chan_456", "target_msg_789")
+    
+    content = "Look at this: https://discord.com/channels/123/456/789"
+    
+    # Test Fluxer
+    resolved_fluxer = resolve_discord_links(content, mock_state, "fluxer", "target_server")
+    assert "https://fluxer.app/channels/target_server/target_chan_456/target_msg_789" in resolved_fluxer
+
+def test_resolve_discord_links_skips_wrapped():
+    mock_state = MagicMock()
+    content = "Already wrapped: [link](https://discord.com/channels/1/2/3)"
+    resolved = resolve_discord_links(content, mock_state, "fluxer", "target_server")
+    assert resolved == content