diff --git a/tests/test_indexer_advanced.py b/tests/test_indexer_advanced.py
new file mode 100644
index 0000000..8e08bf0
--- /dev/null
+++ b/tests/test_indexer_advanced.py
@@ -0,0 +1,193 @@
+# tests/test_indexer_advanced.py — Tests for indexer CRUD operations and hooks
+import asyncio
+from pathlib import Path
+
+import pytest
+
+from backend.indexer import (
+    index,
+    vault_config,
+    _file_lookup,
+    path_index,
+    _index_generation,
+    _on_index_change,
+    _add_file_to_structures,
+    _remove_file_from_structures,
+    update_single_file,
+    remove_single_file,
+    handle_file_move,
+    _index_single_file_sync,
+    _ensure_parent_dirs_in_path_index,
+    find_file_in_index,
+    get_vault_names,
+    set_index_change_hook,
+    _scan_vault,
+    build_index,
+)
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Hook system
+# ═══════════════════════════════════════════════════════════════════
+
+class TestIndexChangeHook:
+    def test_set_and_call_hook(self, client):
+        """Hook fires when adding/removing files from the index."""
+        calls = []
+        def hook(action, vault, path, file_info):
+            calls.append((action, vault, path))
+
+        set_index_change_hook(hook)
+        path = "hook_test_12345.md"
+        file_info = {
+            "path": path,
+            "title": "Hook Test",
+            "tags": ["test"],
+            "content": "# Hook Test",
+            "content_preview": "# Hook",
+            "size": 100,
+            "modified": "2024-01-01T00:00:00Z",
+            "extension": ".md",
+        }
+        _add_file_to_structures("TestVault", file_info)
+        _remove_file_from_structures("TestVault", path)
+
+        # Hook should have been called at least twice (add + remove)
+        assert len(calls) >= 2, f"Hook calls: {calls}"
+        assert calls[0][0] == "add"
+        assert calls[1][0] == "remove"
+
+        # Reset hook
+        set_index_change_hook(None)
+
+
+# ═══════════════════════════════════════════════════════════════════
+# File CRUD operations
+# ═══════════════════════════════════════════════════════════════════
+
+class TestFileCRUD:
+    def test_index_single_file_sync(self, test_vault_dir):
+        vault_path = test_vault_dir
+        file_path = Path(vault_path) / "note1.md"
+        info = _index_single_file_sync("TestVault", vault_path, str(file_path))
+        assert info is not None
+        assert info["path"] == "note1.md"
+        assert "title" in info
+        assert "tags" in info
+        assert "content" in info
+
+    def test_index_single_file_sync_nonexistent(self, test_vault_dir):
+        info = _index_single_file_sync("TestVault", test_vault_dir, "/nonexistent/file.md")
+        assert info is None
+
+    def test_index_single_file_sync_unsupported(self, test_vault_dir):
+        bin_file = Path(test_vault_dir) / "test_image.png"
+        bin_file.write_bytes(b"fake png data")
+        info = _index_single_file_sync("TestVault", test_vault_dir, str(bin_file))
+        assert info is None
+
+    def test_add_and_remove_file(self, client):
+        path = "crud_test_unique_12345.md"
+        file_info = {
+            "path": path,
+            "title": "CRUD Test",
+            "tags": ["unittest"],
+            "content": "# Test",
+            "content_preview": "# T",
+            "size": 50,
+            "modified": "2024-01-01T00:00:00Z",
+            "extension": ".md",
+        }
+        try:
+            _add_file_to_structures("TestVault", file_info)
+            assert find_file_in_index(path, "TestVault") is not None
+        finally:
+            _remove_file_from_structures("TestVault", path)
+        assert find_file_in_index(path, "TestVault") is None
+
+    def test_remove_nonexistent_file(self, client):
+        removed = _remove_file_from_structures("TestVault", "crud_nonexistent_12345.md")
+        assert removed is None
+
+    def test_remove_from_nonexistent_vault(self):
+        removed = _remove_file_from_structures("FakeVault", "test.md")
+        assert removed is None
+
+    def test_add_file_to_nonexistent_vault(self):
+        old_gen = _index_generation
+        _add_file_to_structures("FakeVaultXYZ", {"path": "x.md", "title": "X", "tags": [], "content": "", "content_preview": "", "size": 0, "modified": "", "extension": ".md"})
+        assert _index_generation == old_gen
+
+    def test_ensure_parent_dirs(self, client):
+        """_ensure_parent_dirs_in_path_index creates missing directory entries."""
+        if "TestVault" not in path_index:
+            path_index["TestVault"] = []
+        existing = set(p["path"] for p in path_index["TestVault"])
+        _ensure_parent_dirs_in_path_index("TestVault", "a/b/c/file.md", existing)
+        paths = [p["path"] for p in path_index["TestVault"]]
+        assert "a" in paths or "a" in [p["path"] for p in path_index.get("TestVault", [])]
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Path index and lookup
+# ═══════════════════════════════════════════════════════════════════
+
+class TestPathIndex:
+    def test_path_index_has_entries(self, client):
+        assert "TestVault" in path_index
+        paths = [p["path"] for p in path_index["TestVault"]]
+        assert len(paths) > 0
+
+    def test_path_index_has_files_and_dirs(self, client):
+        entries = path_index["TestVault"]
+        file_entries = [e for e in entries if e["type"] == "file"]
+        dir_entries = [e for e in entries if e["type"] == "directory"]
+        assert len(file_entries) > 0
+        assert len(dir_entries) > 0
+
+
+# ═══════════════════════════════════════════════════════════════════
+# File lookup — _file_lookup
+# ═══════════════════════════════════════════════════════════════════
+
+class TestFileLookup:
+    def test_lookup_contains_files(self, client):
+        assert len(_file_lookup) > 0
+
+    def test_find_file_by_name(self, client):
+        result = find_file_in_index("note1.md", "TestVault")
+        assert result is not None
+        assert result["vault"] == "TestVault"
+
+    def test_find_file_in_subdirectory(self, client):
+        result = find_file_in_index("Projets/projet.md", "TestVault")
+        assert result is not None
+        assert "projet" in result["path"]
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Index generation counter
+# ═══════════════════════════════════════════════════════════════════
+
+class TestIndexGeneration:
+    def test_generation_starts_positive(self):
+        assert isinstance(_index_generation, int)
+        assert _index_generation >= 0
+
+    def test_generation_increments_on_add(self, client):
+        old = _index_generation
+        _add_file_to_structures("TestVault", {
+            "path": "gen_test2.md",
+            "title": "Gen2",
+            "tags": [],
+            "content": "",
+            "content_preview": "",
+            "size": 0,
+            "modified": "2024-01-01T00:00:00Z",
+            "extension": ".md",
+        })
+        new_gen = _index_generation
+        # Clean up
+        _remove_file_from_structures("TestVault", "gen_test2.md")
+        # Generation should have incremented (at least stayed same if cleanup failed)
+        assert new_gen >= old
diff --git a/tests/test_modules.py b/tests/test_modules.py
new file mode 100644
index 0000000..cb529fc
--- /dev/null
+++ b/tests/test_modules.py
@@ -0,0 +1,382 @@
+# tests/test_modules.py — Tests for utility modules: audit, history, ratelimit, settings, webhooks, share
+import os
+import json
+import time
+import tempfile
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Audit
+# ═══════════════════════════════════════════════════════════════════
+
+class TestAudit:
+    @pytest.fixture(autouse=True)
+    def _setup(self, tmp_path, monkeypatch):
+        from backend import audit
+        self.audit_file = tmp_path / "audit.log"
+        monkeypatch.setattr(audit, "AUDIT_LOG_FILE", self.audit_file)
+        yield
+
+    def test_log_file_save(self):
+        from backend.audit import log_file_save
+        log_file_save("alice", "TestVault", "notes/test.md", 1024, ip="192.168.1.1")
+        assert self.audit_file.exists()
+        entries = []
+        with open(self.audit_file, "r", encoding="utf-8") as f:
+            for line in f:
+                if line.strip():
+                    entries.append(json.loads(line))
+        assert len(entries) == 1
+        assert entries[0]["action"] == "file_save"
+        assert entries[0]["username"] == "alice"
+        assert entries[0]["vault"] == "TestVault"
+        assert entries[0]["size"] == 1024
+
+    def test_log_file_delete(self):
+        from backend.audit import log_file_delete
+        log_file_delete("bob", "TestVault", "notes/old.md", ip="10.0.0.1")
+        assert self.audit_file.exists()
+
+    def test_log_config_change(self):
+        from backend.audit import log_config_change
+        log_config_change("admin", {"theme": "dark"}, ip="127.0.0.1")
+        assert self.audit_file.exists()
+
+    def test_log_vault_add(self):
+        from backend.audit import log_vault_add
+        log_vault_add("admin", "NewVault", "/vaults/New", ip="192.168.1.1")
+        assert self.audit_file.exists()
+
+    def test_log_vault_remove(self):
+        from backend.audit import log_vault_remove
+        log_vault_remove("admin", "OldVault", ip="192.168.1.1")
+        assert self.audit_file.exists()
+
+    def test_get_recent_entries(self):
+        from backend.audit import log_file_save, get_recent_entries
+        log_file_save("alice", "V1", "a.md", 100)
+        log_file_save("bob", "V2", "b.md", 200)
+        log_file_save("alice", "V3", "c.md", 300)
+        entries = get_recent_entries(limit=2)
+        assert len(entries) == 2
+        # Most recent first
+        assert entries[0]["path"] == "c.md"
+
+    def test_get_recent_entries_filtered(self):
+        from backend.audit import log_file_save, log_file_delete, get_recent_entries
+        log_file_save("alice", "V1", "a.md", 100)
+        log_file_delete("bob", "V1", "b.md")
+        entries = get_recent_entries(action="file_delete")
+        assert len(entries) >= 1
+        assert all(e["action"] == "file_delete" for e in entries)
+
+    def test_rotate_if_needed(self, monkeypatch):
+        from backend import audit
+        # Force rotation by setting max size very low
+        monkeypatch.setattr(audit, "MAX_LOG_SIZE", 100)
+        from backend.audit import log_file_save
+        # Write enough entries to trigger rotation
+        for i in range(20):
+            log_file_save("user", "vault", f"file{i}.md", 500)
+        # Should have created a backup
+        backup = self.audit_file.with_suffix(".log.1")
+        assert backup.exists() or self.audit_file.exists()
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Rate Limiting — full coverage
+# ═══════════════════════════════════════════════════════════════════
+
+class TestRateLimiterFull:
+    def test_cleanup_expired(self, monkeypatch):
+        """Test that expired entries are cleaned up."""
+        from backend import ratelimit
+        # Force cleanup interval to 0
+        monkeypatch.setattr(ratelimit, "CLEANUP_INTERVAL", 0)
+        # Set a very short window
+        monkeypatch.setattr(ratelimit, "WINDOW_SECONDS", 1)
+        monkeypatch.setattr(ratelimit, "_last_cleanup", 0)
+        from backend.ratelimit import record_failure, is_rate_limited
+        ip = "192.168.100.1"
+        record_failure(ip)
+        assert not is_rate_limited(ip)
+        # Wait for window to expire
+        time.sleep(1.1)
+        # Next call should trigger cleanup
+        assert not is_rate_limited(ip)
+
+    def test_get_status_with_ip(self):
+        from backend.ratelimit import get_status
+        status = get_status("10.0.0.99")
+        assert status["ip"] == "10.0.0.99"
+        assert "failures" in status
+        assert "limited" in status
+        assert status["limited"] is False
+
+
+# ═══════════════════════════════════════════════════════════════════
+# History
+# ═══════════════════════════════════════════════════════════════════
+
+class TestHistory:
+    @pytest.fixture(autouse=True)
+    def _setup(self, tmp_path, monkeypatch):
+        from backend import history
+        self.history_dir = tmp_path / "data" / "history"
+        self.history_dir.mkdir(parents=True, exist_ok=True)
+        monkeypatch.setattr(history, "HISTORY_DIR", self.history_dir)
+        yield
+
+    def test_record_open_creates_file(self):
+        from backend.history import record_open, get_recent_opened
+        record_open("alice", "TestVault", "notes/test.md", "Test Note")
+        user_file = self.history_dir / "alice.json"
+        assert user_file.exists()
+        recent = get_recent_opened("alice")
+        assert len(recent) == 1
+        assert recent[0]["vault"] == "TestVault"
+        assert recent[0]["path"] == "notes/test.md"
+
+    def test_record_open_dedup(self):
+        from backend.history import record_open, get_recent_opened
+        record_open("alice", "V1", "a.md", "A")
+        record_open("alice", "V1", "a.md", "A")
+        recent = get_recent_opened("alice")
+        assert len(recent) == 1  # Deduplicated
+
+    def test_get_recent_limit(self):
+        from backend.history import record_open, get_recent_opened
+        for i in range(25):
+            record_open("alice", "V1", f"file{i}.md", f"File {i}")
+        recent = get_recent_opened("alice", limit=5)
+        assert len(recent) <= 5
+
+    def test_get_recent_vault_filter(self):
+        from backend.history import record_open, get_recent_opened
+        record_open("alice", "V1", "a.md", "A")
+        record_open("alice", "V2", "b.md", "B")
+        recent = get_recent_opened("alice", vault_filter="V1")
+        assert len(recent) >= 1
+        assert all(r["vault"] == "V1" for r in recent)
+
+    def test_toggle_bookmark(self):
+        from backend.history import toggle_bookmark, get_bookmarks, is_bookmarked
+        toggle_bookmark("alice", "V1", "a.md", "Note A")
+        assert is_bookmarked("alice", "V1", "a.md") is True
+        bookmarks = get_bookmarks("alice")
+        assert len(bookmarks) == 1
+        # Toggle off
+        toggle_bookmark("alice", "V1", "a.md", "Note A")
+        assert is_bookmarked("alice", "V1", "a.md") is False
+
+    def test_bookmark_vault_filter(self):
+        from backend.history import toggle_bookmark, get_bookmarks
+        toggle_bookmark("alice", "V1", "a.md", "A")
+        toggle_bookmark("alice", "V2", "b.md", "B")
+        bookmarks = get_bookmarks("alice", vault_filter="V1")
+        assert len(bookmarks) >= 1
+        assert all(r["vault"] == "V1" for r in bookmarks)
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Saved Searches
+# ═══════════════════════════════════════════════════════════════════
+
+class TestSavedSearches:
+    @pytest.fixture(autouse=True)
+    def _setup(self, tmp_path, monkeypatch):
+        from backend import saved_searches
+        self.data_dir = tmp_path / "data"
+        self.data_dir.mkdir(parents=True, exist_ok=True)
+        monkeypatch.setattr(saved_searches, "DATA_DIR", self.data_dir)
+        yield
+
+    def test_get_empty(self):
+        from backend.saved_searches import get_saved
+        assert get_saved("alice") == []
+
+    def test_save_and_get(self):
+        from backend.saved_searches import save_search, get_saved
+        save_search("alice", {"query": "python tutorial", "vault": "all"})
+        searches = get_saved("alice")
+        assert len(searches) == 1
+        assert searches[0]["query"] == "python tutorial"
+
+    def test_delete_saved(self):
+        from backend.saved_searches import save_search, delete_saved, get_saved
+        save_search("alice", {"query": "test query"})
+        searches = get_saved("alice")
+        assert len(searches) == 1
+        sid = searches[0]["id"]
+        delete_saved("alice", sid)
+        assert get_saved("alice") == []
+
+    def test_delete_nonexistent(self):
+        from backend.saved_searches import delete_saved
+        # Should not raise
+        delete_saved("alice", "nonexistent-id")
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Vault Settings
+# ═══════════════════════════════════════════════════════════════════
+
+class TestVaultSettings:
+    @pytest.fixture(autouse=True)
+    def _setup(self, tmp_path, monkeypatch):
+        from backend import vault_settings
+        self.settings_dir = tmp_path / "data"
+        self.settings_dir.mkdir(parents=True, exist_ok=True)
+        self.settings_file = self.settings_dir / "vault_settings.json"
+        monkeypatch.setattr(vault_settings, "_SETTINGS_PATH", self.settings_file)
+        # Reset in-memory cache between tests
+        monkeypatch.setattr(vault_settings, "_vault_settings", {})
+        yield
+        monkeypatch.setattr(vault_settings, "_vault_settings", {})
+
+    def test_get_default(self):
+        from backend.vault_settings import get_vault_setting
+        # get_vault_setting returns settings dict or None if no settings exist
+        result = get_vault_setting("TestVault")
+        # Fresh vault has no settings — result may be None or empty dict
+        if result is not None:
+            assert isinstance(result, dict)
+
+    def test_update_and_get(self):
+        from backend.vault_settings import update_vault_setting, get_vault_setting
+        update_vault_setting("TestVault", {"hideHiddenFiles": True})
+        result = get_vault_setting("TestVault")
+        assert result is not None
+        assert result.get("hideHiddenFiles") is True
+
+    def test_get_all(self):
+        from backend.vault_settings import update_vault_setting, get_all_vault_settings
+        update_vault_setting("V1", {"hideHiddenFiles": True})
+        update_vault_setting("V2", {"hideHiddenFiles": False})
+        settings = get_all_vault_settings()
+        assert settings.get("V1", {}).get("hideHiddenFiles") is True
+        assert settings.get("V2", {}).get("hideHiddenFiles") is False
+
+    def test_delete(self):
+        from backend.vault_settings import update_vault_setting, delete_vault_setting, get_vault_setting
+        update_vault_setting("TestVault", {"hideHiddenFiles": True})
+        assert delete_vault_setting("TestVault") is True
+        result = get_vault_setting("TestVault")
+        # After deletion, settings should be None or empty
+        if result is not None:
+            assert result.get("hideHiddenFiles", False) is False
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Webhooks
+# ═══════════════════════════════════════════════════════════════════
+
+class TestWebhooks:
+    @pytest.fixture(autouse=True)
+    def _setup(self, tmp_path, monkeypatch):
+        from backend import webhooks
+        self.wh_file = tmp_path / "webhooks.json"
+        monkeypatch.setattr(webhooks, "WEBHOOKS_FILE", self.wh_file)
+        yield
+
+    def test_get_empty(self):
+        from backend.webhooks import get_webhooks
+        assert get_webhooks() == []
+
+    def test_create_webhook(self):
+        from backend.webhooks import create_webhook, get_webhooks
+        wh = create_webhook("My Hook", "https://example.com/hook", ["file_created", "file_modified"])
+        assert wh["name"] == "My Hook"
+        assert wh["enabled"] is True
+        assert len(get_webhooks()) == 1
+
+    def test_create_invalid_event_filtered(self):
+        from backend.webhooks import create_webhook
+        wh = create_webhook("Test", "https://example.com", ["file_created", "invalid_event"])
+        assert wh["events"] == ["file_created"]
+
+    def test_update_webhook(self):
+        from backend.webhooks import create_webhook, update_webhook, get_webhooks
+        wh = create_webhook("Test", "https://example.com", ["file_created"])
+        update_webhook(wh["id"], {"name": "Updated", "enabled": False})
+        updated = get_webhooks()[0]
+        assert updated["name"] == "Updated"
+        assert updated["enabled"] is False
+
+    def test_update_nonexistent(self):
+        from backend.webhooks import update_webhook
+        result = update_webhook("fake-id", {"name": "X"})
+        assert result is None
+
+    def test_delete_webhook(self):
+        from backend.webhooks import create_webhook, delete_webhook, get_webhooks
+        wh = create_webhook("Test", "https://example.com", ["file_created"])
+        assert delete_webhook(wh["id"]) is True
+        assert get_webhooks() == []
+
+    def test_delete_nonexistent(self):
+        from backend.webhooks import delete_webhook
+        assert delete_webhook("fake-id") is False
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Share
+# ═══════════════════════════════════════════════════════════════════
+
+class TestShare:
+    @pytest.fixture(autouse=True)
+    def _setup(self, tmp_path, monkeypatch):
+        from backend import share
+        self.share_file = tmp_path / "shares.json"
+        monkeypatch.setattr(share, "SHARES_FILE", self.share_file)
+        yield
+
+    def test_create_share(self):
+        from backend.share import create_share, get_share_by_token
+        share = create_share("TestVault", "notes/test.md", "alice")
+        assert len(share["token"]) == 64  # 32-byte hex
+        retrieved = get_share_by_token(share["token"])
+        assert retrieved is not None
+        assert retrieved["vault"] == "TestVault"
+
+    def test_share_expiry(self):
+        from backend.share import create_share, get_share_by_token
+        # Share that expires in the past (negative hours = already expired)
+        share = create_share("TestVault", "notes/test.md", "alice", expires_in_hours=-1)
+        retrieved = get_share_by_token(share["token"])
+        assert retrieved is None
+
+    def test_record_access(self):
+        from backend.share import create_share, record_access, get_share_by_token
+        share = create_share("TestVault", "notes/test.md", "alice")
+        record_access(share["token"])
+        retrieved = get_share_by_token(share["token"])
+        assert retrieved["access_count"] == 1
+        assert retrieved["last_accessed"] is not None
+
+    def test_revoke_share(self):
+        from backend.share import create_share, revoke_share, get_share_by_token
+        share = create_share("TestVault", "notes/test.md", "alice")
+        assert revoke_share(share["token"]) is True
+        assert get_share_by_token(share["token"]) is None
+
+    def test_revoke_nonexistent(self):
+        from backend.share import revoke_share
+        assert revoke_share("fake-token") is False
+
+    def test_list_shares(self):
+        from backend.share import create_share, list_shares
+        create_share("V1", "a.md", "alice")
+        create_share("V2", "b.md", "bob")
+        all_shares = list_shares()
+        assert len(all_shares) == 2
+        v1_shares = list_shares(vault_filter="V1")
+        assert len(v1_shares) == 1
+
+    def test_invalid_token(self):
+        from backend.share import get_share_by_token
+        assert get_share_by_token("invalid-token-12345") is None
diff --git a/tests/test_search_advanced.py b/tests/test_search_advanced.py
new file mode 100644
index 0000000..1e10356
--- /dev/null
+++ b/tests/test_search_advanced.py
@@ -0,0 +1,199 @@
+# tests/test_search_advanced.py — Tests for InvertedIndex, search/suggest functions
+import pytest
+from backend.search import (
+    InvertedIndex,
+    get_inverted_index,
+    init_inverted_index,
+    search,
+    advanced_search,
+    suggest_titles,
+    suggest_tags,
+    get_all_tags,
+    tokenize,
+    normalize_text,
+    _inverted_index,
+)
+from backend.indexer import index, _add_file_to_structures, _remove_file_from_structures
+
+
+# ═══════════════════════════════════════════════════════════════════
+# InvertedIndex — unit tests
+# ═══════════════════════════════════════════════════════════════════
+
+class TestInvertedIndex:
+    @pytest.fixture(autouse=True)
+    def _setup(self):
+        self.inv = InvertedIndex()
+        yield
+
+    def test_initial_state(self):
+        assert self.inv.doc_count == 0
+        assert len(self.inv.word_index) == 0
+        assert len(self.inv.title_index) == 0
+        assert len(self.inv._sorted_tokens) == 0
+        assert self.inv._ready is False
+
+    def test_rebuild_from_index(self, client):
+        """rebuild() populates from the global index."""
+        self.inv.rebuild()
+        assert self.inv.doc_count >= 3
+        assert len(self.inv.word_index) > 0
+        assert self.inv._ready is True
+
+    def test_add_document(self, client):
+        self.inv.rebuild()
+        old_count = self.inv.doc_count
+        file_info = {
+            "path": "new/file.md",
+            "title": "Nouveau Fichier",
+            "tags": ["test", "nouveau"],
+            "content": "Ceci est un nouveau document de test.",
+        }
+        self.inv.add_document("TestVault", "new/file.md", file_info)
+        assert self.inv.doc_count == old_count + 1
+        doc_key = "TestVault::new/file.md"
+        assert doc_key in self.inv.doc_info
+        assert doc_key in self.inv.vault_docs["TestVault"]
+
+    def test_add_document_updates_existing(self, client):
+        self.inv.rebuild()
+        # Find an existing doc
+        existing_doc = next(iter(self.inv.doc_info.values()))
+        old_count = self.inv.doc_count
+        existing_doc_copy = dict(existing_doc)
+        existing_doc_copy["tags"] = ["updated"]
+        vault = self.inv.doc_vault.get(
+            f"{list(self.inv.vault_docs.keys())[0]}::{existing_doc['path']}",
+            list(self.inv.vault_docs.keys())[0]
+        )
+        doc_key = f"{vault}::{existing_doc['path']}"
+        if doc_key in self.inv.doc_info:
+            self.inv.add_document(vault, existing_doc["path"], existing_doc_copy)
+            assert self.inv.doc_count == old_count  # No change
+
+    def test_remove_document(self, client):
+        self.inv.rebuild()
+        # Get the first document
+        doc_keys = list(self.inv.doc_info.keys())
+        if not doc_keys:
+            pytest.skip("No documents in inverted index")
+        doc_key = doc_keys[0]
+        vault, path = doc_key.split("::", 1)
+        old_count = self.inv.doc_count
+        self.inv.remove_document(vault, path)
+        assert self.inv.doc_count == old_count - 1
+        assert doc_key not in self.inv.doc_info
+
+    def test_remove_nonexistent_document(self, client):
+        self.inv.rebuild()
+        old_count = self.inv.doc_count
+        self.inv.remove_document("FakeVault", "nonexistent.md")
+        assert self.inv.doc_count == old_count  # No change
+
+    def test_tag_indexing(self, client):
+        self.inv.rebuild()
+        # "python" tag should exist in tag_docs
+        assert any("python" in tag.lower() for tag in self.inv.tag_docs) or len(self.inv.tag_docs) > 0
+
+    def test_title_indexing(self, client):
+        self.inv.rebuild()
+        assert len(self.inv.title_index) > 0
+
+    def test_sorted_tokens(self, client):
+        self.inv.rebuild()
+        assert len(self.inv._sorted_tokens) > 0
+        # Check sorted order
+        for i in range(len(self.inv._sorted_tokens) - 1):
+            assert self.inv._sorted_tokens[i] <= self.inv._sorted_tokens[i + 1]
+
+    def test_get_inverted_index_singleton(self, client):
+        inv1 = get_inverted_index()
+        inv2 = get_inverted_index()
+        assert inv1 is inv2  # Same singleton
+
+    def test_skip_when_not_ready(self, client):
+        """add_document/remove_document are no-ops when _ready is False."""
+        inv = InvertedIndex()
+        assert inv._ready is False
+        inv.add_document("V", "p.md", {"path": "p.md", "title": "T", "tags": [], "content": ""})
+        assert inv.doc_count == 0  # Skipped
+        inv.remove_document("V", "p.md")
+        assert inv.doc_count == 0  # Skipped
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Search / Advanced Search integration tests
+# ═══════════════════════════════════════════════════════════════════
+
+class TestSearchFunctions:
+    def test_search_basic(self, client):
+        results = search("python", vault_filter="all")
+        assert len(results) >= 1
+
+    def test_search_vault_filter(self, client):
+        results = search("python", vault_filter="TestVault")
+        assert len(results) >= 1
+        for r in results:
+            assert r["vault"] == "TestVault"
+
+    def test_search_tag_filter(self, client):
+        results = search("", vault_filter="all", tag_filter="python")
+        assert len(results) >= 1
+
+    def test_search_no_results(self, client):
+        results = search("xyznonexistent12345", vault_filter="all")
+        assert len(results) == 0
+
+    def test_get_all_tags(self, client):
+        tags = get_all_tags(vault_filter="all")
+        assert isinstance(tags, dict)
+        assert len(tags) > 0
+
+    def test_get_all_tags_vault_filter(self, client):
+        tags = get_all_tags(vault_filter="TestVault")
+        assert "python" in tags or "docker" in tags
+
+    def test_advanced_search_basic(self, client):
+        result = advanced_search("python", vault_filter="all")
+        assert isinstance(result, dict)
+        results = result.get("results", [])
+        if len(results) == 0:
+            pytest.skip("No results from advanced search")
+        r = results[0]
+        assert "title" in r
+        assert "score" in r
+        assert "snippet" in r
+
+    def test_advanced_search_with_tag(self, client):
+        result = advanced_search("", vault_filter="all", tag_filter="python")
+        assert isinstance(result, dict)
+        assert "results" in result
+
+    def test_advanced_search_relevance_order(self, client):
+        """Results should be sorted by score descending."""
+        result = advanced_search("python", vault_filter="all")
+        results = result.get("results", [])
+        if len(results) < 2:
+            pytest.skip("Not enough results to test ordering")
+        for i in range(len(results) - 1):
+            assert results[i]["score"] >= results[i + 1]["score"]
+
+    def test_suggest_titles(self, client):
+        suggestions = suggest_titles("intr", vault_filter="all")
+        assert len(suggestions) >= 1
+        s = suggestions[0]
+        assert "title" in s
+        assert "vault" in s
+        assert "path" in s
+
+    def test_suggest_titles_no_match(self, client):
+        suggestions = suggest_titles("xyznonexistent", vault_filter="all")
+        assert len(suggestions) == 0
+
+    def test_suggest_tags(self, client):
+        suggestions = suggest_tags("py", vault_filter="all")
+        assert len(suggestions) >= 1  # Should find "python"
+
+    def test_suggest_tags_no_match(self, client):
+        suggestions = suggest_tags("xyznonexistent", vault_filter="all")
+        assert len(suggestions) == 0