Autocomplete (#46)

* Add smart SQL autocomplete with context-aware suggestions

- New SQL completion engine using sqlparse for context detection
- Suggests tables after FROM/JOIN, columns after WHERE/SELECT, operators after column names
- Lazy loading of columns to avoid UI lag during schema indexing
- Scrollable autocomplete dropdown with keyboard navigation
- Auto-hide when cursor moves away from typing position
- Fuzzy matching and alias resolution support

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* fix: prompt for password when connection password is empty

Previously, an empty string password was treated differently from None,
meaning connections with empty passwords would fail instead of prompting
the user. Now both None and empty string trigger the password prompt.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* fix: add Azure SQL Database compatibility for MSSQL adapter

Azure SQL Database does not support cross-database queries or USE
statements. This fix:

- Adds _get_cursor_for_database() that tries USE first (fast for
  regular SQL Server), then falls back to creating a new connection
  with the target database (for Azure SQL)
- Stores config and driver on connection object for reconnection
- Removes all cross-database reference syntax ([Database].schema.table)
- Updates all adapter methods to use the new approach

Also adds unit tests verifying no cross-database references are used,
and integration tests for Azure SQL Database.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* refactor: split SQL completion into separate modules by statement type

Reorganizes sql_completion.py into a package with separate modules:
- core.py: base classes and utilities
- completion.py: main SQLCompletion class
- alter_table.py, create_table.py, create_index.py, create_view.py,
  delete.py, drop.py, insert.py, truncate.py, update.py: statement handlers

Also introduces QueryTextArea widget that wraps TextArea with SQL
autocomplete functionality, simplifying the integration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* fix: don't show completions without SQL context

- Return empty completions when there's no SQL content yet (just
  whitespace). This prevents showing irrelevant keywords when pressing
  space/enter on an empty query.
- Add handlers for IN ( and EXISTS ( patterns to suggest SELECT for
  subqueries.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* fix: use correct database context when clicking tables in tree

For Azure SQL Database, clicking a table from a different database now
correctly executes the query against that database:

- build_select_query no longer includes [database] prefix (breaks Azure)
- Added _query_target_database to track which database to query
- Query execution uses apply_database_override when target differs
- Target database is cleared after use to not affect user-typed queries

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* fix: use fully qualified table names in autocomplete when no default database

When connected without a default database (multiple databases visible),
autocomplete now suggests fully qualified names like [db].[schema].[table]
instead of just table names. This allows queries to work correctly.

Uses adapter.quote_identifier() for proper quoting (brackets for SQL Server).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* feat: idle scheduler for background schema loading and UX improvements

Idle Scheduler:
- Add idle scheduler inspired by browser's requestIdleCallback API
- Execute background work during user idle periods (500ms threshold)
- Queue schema loading (tables/views/procedures) as idle jobs
- Add --debug-idle-scheduler flag to show scheduler status bar
- Preload columns for tables found in query editor during idle

Shared Cache:
- Tree and autocomplete now share _db_object_cache for tables/views/procedures
- Expanding tree nodes populates autocomplete cache and vice versa
- Refresh ('f') clears both object cache and column cache

Azure SQL:
- Add separate AzureSQLAdapter with required database field
- Simplify MSSQL adapter by removing Azure-specific fallback logic

Autocomplete UX:
- Add *, DISTINCT, TOP, ALL to SELECT clause completions
- Remove table names from SELECT suggestions (belong after FROM)
- Dropdown stays visible when window loses focus
- Dropdown constrained to stay within bounds (no right-edge cutoff)

* Enter key dismisses autocomplete instead of accepting

- Enter now hides the autocomplete dropdown and inserts a newline
- Only Tab accepts autocomplete suggestions
- Added suppress flag to prevent autocomplete from re-triggering
  after Enter dismisses it (newline text change was re-showing dropdown)

* Persist active database preference across sessions

Introduces _active_database separate from current_config.database to
preserve tree structure while allowing users to set a preferred database.

- Added get/set_database_preference() to config.py for persistence
- On connect: load cached preference into _active_database
- On 'u' press: save preference and reload schema for new database
- On disconnect: clear _active_database
- Star display in tree now uses _active_database
- Autocomplete schema loading now respects _active_database

The connection config (and tree structure) remains unchanged - only the
user's runtime preference is cached in settings.json.

* Add system_databases property per adapter and fix ESC behavior

- Add system_databases property to DatabaseAdapter base class
- Define system databases for each adapter:
  - MSSQL: master, tempdb, model, msdb
  - PostgreSQL: template0, template1
  - MySQL/MariaDB: mysql, information_schema, performance_schema, sys
  - ClickHouse: system, information_schema
  - Snowflake: SNOWFLAKE
- Update autocomplete to filter using adapter.system_databases
- ESC key now closes autocomplete AND exits to normal mode
- Add unit tests for system_databases property

* Fix ESC key priority on modal screens

Add priority=True to escape bindings on all modal screens to ensure
ESC key is handled correctly when other bindings are active.

* Fix error display in results table

Flatten multi-line error messages to single line since DataTable cells
only display one line. Replaces textwrap with regex whitespace collapse.

* Add supports_cross_database_queries property and auto-switch databases

- Add supports_cross_database_queries property to DatabaseAdapter
  - Returns True for MSSQL, MySQL, ClickHouse, Snowflake (support USE)
  - Returns False for PostgreSQL, CockroachDB, D1 (require reconnection)
- Add switch_database() method to ConnectionSession for reconnecting
  to a different database while reusing SSH tunnel
- Auto-switch database when expanding database nodes or their contents
  - For cross-db adapters: sets active database (USE approach)
  - For non-cross-db adapters: reconnects to the database
  - Falls back to reconnection if USE fails (e.g., Azure SQL)
- Remove 'u' keybinding - Enter on database node now sets it active
- Apply active database to query execution context
- Add helper functions in providers.py for database requirement checks
- Update tests with new mock attributes

* Remove Azure SQL adapter - use MSSQL with automatic fallback

Azure SQL is now handled by the MSSQL adapter with automatic fallback:
- If USE statement fails, automatically reconnect to target database
- Retry the operation after reconnection
- Show original error only if reconnection also fails

This makes Azure SQL work transparently without a separate adapter.

* Handle cross-db capability in autocomplete

* Handle ESC in leader menu

* Add tests for autocomplete database modes

* Add autocomplete demo gifs

* Hide autocomplete after statement terminator (semicolon)

Previously, typing a semicolon after a complete statement would show
irrelevant suggestions (tables or keywords). Now the autocomplete
popup hides when the cursor is immediately after a semicolon.

* Remove db caching

* Fix password prompt for explicitly empty passwords

- Only prompt for password when password is None (not set), not when
  it's an empty string (explicitly set to empty)
- Some databases allow passwordless connections, so "" should be valid
- Remove Azure SQL adapter tests (adapter was removed)

---------

Co-authored-by: Peter Adams <18162810+Maxteabag@users.noreply.github.com>

Author: Maxteabag

demos/autocomplete-01-basics.gif

@@ -31,6 +31,7 @@ dependencies = [
     "pyperclip>=1.8.2",
     "keyring>=24.0.0",
     "docker>=7.0.0",
+    "sqlparse>=0.5.0",
 ]
 dynamic = ["version"]
 

demos/autocomplete-02-select-from.gif

@@ -17,7 +17,9 @@
 from textual.lazy import Lazy
 from textual.screen import ModalScreen
 from textual.timer import Timer
-from textual.widgets import Static, TextArea, Tree
+from textual.widgets import Static, Tree
+
+from .widgets import QueryTextArea
 from textual.worker import Worker
 
 from .config import (
@@ -51,6 +53,7 @@
     TreeFilterInput,
     VimMode,
 )
+from .idle_scheduler import init_idle_scheduler, on_user_activity, IdleScheduler
 
 
 class SSMSTUI(
@@ -208,6 +211,17 @@ class SSMSTUI(
         padding: 0 1;
     }
 
+    #idle-scheduler-bar {
+        height: 1;
+        background: $primary-darken-3;
+        padding: 0 1;
+        display: none;
+    }
+
+    #idle-scheduler-bar.visible {
+        display: block;
+    }
+
     #sidebar,
     #query-area,
     #results-area {
@@ -260,7 +274,6 @@ class SSMSTUI(
         Binding("z", "collapse_tree", "Collapse", show=False),
         Binding("j", "tree_cursor_down", "Down", show=False),
         Binding("k", "tree_cursor_up", "Up", show=False),
-        Binding("u", "use_database", "Use as default", show=False),
         Binding("v", "view_cell", "View cell", show=False),
         Binding("u", "edit_cell", "Update cell", show=False),
         Binding("h", "results_cursor_left", "Left", show=False),
@@ -297,6 +310,7 @@ def __init__(
         self._startup_connection = startup_connection
         self._startup_connect_config: ConnectionConfig | None = None
         self._debug_mode = os.environ.get("SQLIT_DEBUG") == "1"
+        self._debug_idle_scheduler = os.environ.get("SQLIT_DEBUG_IDLE_SCHEDULER") == "1"
         self._startup_profile = os.environ.get("SQLIT_PROFILE_STARTUP") == "1"
         self._startup_mark = self._parse_startup_mark(os.environ.get("SQLIT_STARTUP_MARK"))
         self._startup_init_time = time.perf_counter()
@@ -355,7 +369,9 @@ def __init__(
         self._state_machine = UIStateMachine()
         self._session_factory: Any | None = None
         self._last_query_table: dict | None = None
-        # Omarchy theme sync state
+        self._query_target_database: str | None = None  # Target DB for auto-generated queries
+        # Idle scheduler for background work
+        self._idle_scheduler: IdleScheduler | None = None
 
         if mock_profile:
             self._session_factory = self._create_mock_session_factory(mock_profile)
@@ -387,8 +403,8 @@ def object_tree(self) -> Tree:
         return self.query_one("#object-tree", Tree)
 
     @property
-    def query_input(self) -> TextArea:
-        return self.query_one("#query-input", TextArea)
+    def query_input(self) -> QueryTextArea:
+        return self.query_one("#query-input", QueryTextArea)
 
     @property
     def results_table(self) -> SqlitDataTable:
@@ -416,6 +432,10 @@ def results_area(self) -> Any:
     def status_bar(self) -> Static:
         return self.query_one("#status-bar", Static)
 
+    @property
+    def idle_scheduler_bar(self) -> Static:
+        return self.query_one("#idle-scheduler-bar", Static)
+
     @property
     def autocomplete_dropdown(self) -> Any:
         from .widgets import AutocompleteDropdown
@@ -509,7 +529,7 @@ def compose(self) -> ComposeResult:
 
                 with Vertical(id="main-panel"):
                     with Container(id="query-area"):
-                        yield TextArea(
+                        yield QueryTextArea(
                             "",
                             language="sql",
                             id="query-input",
@@ -521,6 +541,7 @@ def compose(self) -> ComposeResult:
                         yield ResultsFilterInput(id="results-filter")
                         yield Lazy(SqlitDataTable(id="results-table", zebra_stripes=True, show_header=False))
 
+            yield Static("", id="idle-scheduler-bar")
             yield Static("Not connected", id="status-bar")
 
         yield ContextFooter()
@@ -531,6 +552,15 @@ def on_mount(self) -> None:
         self._startup_stamp("on_mount_start")
         self._restart_argv = self._compute_restart_argv()
 
+        # Initialize and start idle scheduler
+        self._idle_scheduler = init_idle_scheduler(self)
+        self._idle_scheduler.start()
+
+        # Show idle scheduler debug bar if enabled
+        if self._debug_idle_scheduler:
+            self.idle_scheduler_bar.add_class("visible")
+            self._idle_scheduler_bar_timer = self.set_interval(0.1, self._update_idle_scheduler_bar)
+
         self._theme_manager.register_builtin_themes()
         self._theme_manager.register_textarea_themes()
 

demos/autocomplete-03-joins.gif

@@ -161,6 +161,11 @@ def main() -> int:
         action="store_true",
         help="Show startup timing in the status bar.",
     )
+    parser.add_argument(
+        "--debug-idle-scheduler",
+        action="store_true",
+        help="Show idle scheduler status in the status bar.",
+    )
 
     subparsers = parser.add_subparsers(dest="command", help="Available commands")
 
@@ -284,6 +289,10 @@ def main() -> int:
         os.environ["SQLIT_DEBUG"] = "1"
     else:
         os.environ.pop("SQLIT_DEBUG", None)
+    if args.debug_idle_scheduler:
+        os.environ["SQLIT_DEBUG_IDLE_SCHEDULER"] = "1"
+    else:
+        os.environ.pop("SQLIT_DEBUG_IDLE_SCHEDULER", None)
     if args.profile_startup or args.debug:
         os.environ["SQLIT_STARTUP_MARK"] = str(startup_mark)
     else:

demos/autocomplete-04-clauses.gif

@@ -88,6 +88,7 @@ def get_all_schemas() -> Any:
     "SchemaField": ("sqlit.db.schema", "SchemaField"),
     "SelectOption": ("sqlit.db.schema", "SelectOption"),
     # Adapters (through sqlit.db.adapters, which itself lazy-loads)
+    "AzureSQLAdapter": ("sqlit.db.adapters", "AzureSQLAdapter"),
     "CockroachDBAdapter": ("sqlit.db.adapters", "CockroachDBAdapter"),
     "DuckDBAdapter": ("sqlit.db.adapters", "DuckDBAdapter"),
     "FirebirdAdapter": ("sqlit.db.adapters", "FirebirdAdapter"),

pyproject.toml

@@ -182,12 +182,37 @@ def supports_multiple_databases(self) -> bool:
         """Whether this database type supports multiple databases."""
         pass
 
+    @property
+    def supports_cross_database_queries(self) -> bool:
+        """Whether this database supports cross-database queries.
+
+        When True, queries can reference tables in other databases using
+        fully qualified names (e.g., [db].[schema].[table] in SQL Server).
+
+        When False, each database is isolated and a specific database must
+        be selected before querying. Connection creation will require a
+        database to be specified.
+
+        Defaults to True. Override in subclasses for databases like PostgreSQL
+        where each database is isolated.
+        """
+        return True
+
     @property
     @abstractmethod
     def supports_stored_procedures(self) -> bool:
         """Whether this database type supports stored procedures."""
         pass
 
+    @property
+    def system_databases(self) -> frozenset[str]:
+        """Set of system database names to exclude from user listings.
+
+        Override in subclasses for database-specific system databases.
+        Returns lowercase names for case-insensitive comparison.
+        """
+        return frozenset()
+
     @property
     def default_schema(self) -> str:
         """The default schema for this database type.
@@ -250,6 +275,10 @@ def validate_config(self, config: ConnectionConfig) -> None:
         """Validate provider-specific config values."""
         return None
 
+    def detect_capabilities(self, conn: Any, config: ConnectionConfig) -> None:
+        """Detect runtime capabilities after establishing a connection."""
+        return None
+
     def get_auth_type(self, config: ConnectionConfig) -> Any | None:
         """Return the provider-specific auth type, if applicable."""
         return None
@@ -567,6 +596,10 @@ class MySQLBaseAdapter(CursorBasedAdapter):
     def supports_multiple_databases(self) -> bool:
         return True
 
+    @property
+    def system_databases(self) -> frozenset[str]:
+        return frozenset({"mysql", "information_schema", "performance_schema", "sys"})
+
     @property
     def supports_stored_procedures(self) -> bool:
         return True
@@ -821,6 +854,15 @@ def supports_multiple_databases(self) -> bool:
     def supports_stored_procedures(self) -> bool:
         return True
 
+    @property
+    def system_databases(self) -> frozenset[str]:
+        return frozenset({"template0", "template1"})
+
+    @property
+    def supports_cross_database_queries(self) -> bool:
+        """PostgreSQL databases are isolated; cross-database queries not supported."""
+        return False
+
     @property
     def default_schema(self) -> str:
         return "public"

sqlit/app.py

@@ -61,6 +61,10 @@ def driver_import_names(self) -> tuple[str, ...]:
     def supports_multiple_databases(self) -> bool:
         return True
 
+    @property
+    def system_databases(self) -> frozenset[str]:
+        return frozenset({"system", "information_schema", "INFORMATION_SCHEMA"})
+
     @property
     def supports_stored_procedures(self) -> bool:
         # ClickHouse doesn't have traditional stored procedures