DB viewer + query editor enhancements (home-screen-ux-query-editor) (#4)

* feat: add query_history table migration (v5) (Task 1)

* feat: add isDestructiveQuery utility (Task 2)

* feat: add tabType discriminator and openQueryTab to dbViewerStore (Task 3)

* feat: add execute_query command with pagination and query history (Task 4)

* feat: add typed wrappers for executeQuery, getQueryHistory, clearQueryHistory (Task 5)

* fix: global search bypasses folder scope when filters active (Task 6)

* feat: add TagFilterDropdown with checkboxes and empty state (Task 7)

* feat: add DbTypeFilterDropdown with checkboxes and clear all (Task 8)

* feat: wire TagFilterDropdown/DbTypeFilterDropdown into ActionRow, add inline tag creation (Task 9)

* feat: add Name input to GeneralTab for connection editing (Task 10)

* feat: add QueryEditor Monaco wrapper with SQL mode and Cmd+Enter (Task 11)

* feat: add DestructiveQueryDialog with SQL preview and confirmation (Task 12)

* feat: integrate query tabs, Monaco editor, destructive guard into DbViewerScreen (Task 13)

* fix: harden moveConnection against race conditions on rapid drags (Task 14)

* docs: update AGENTS.md implementation status for Home Screen UX + Query Editor (Task 15)

* feat: switch tag filter to OR semantics, add environment filter (F-T16)

* feat: add activeEnvironment filter state to uiStore and useFilteredConnections (F-T17)

* feat: add environment filter select to Filters dropdown (F-T18)

* feat: filter folder cards by tag match or contained connections (F-T19)

* fix: keep grid header width to content, border last column

* fix: hide select-all checkbox and empty-state when no table open

* fix: filter folder cards by any active filter, show global search results (F-T20)

* feat: show 'Showing Search Results' breadcrumb with clear button (F-T21)

* docs: update README + AGENTS.md for Query Editor, filters, and planned AI integration (BYOK)

* feat: refresh indicator with spinning icon and pulse, defer auto-refresh on tab switch

* feat: smart default schema selection, refresh schemas on database switch

* fix: auto-refresh waits for in-flight refresh to complete before next tick

* style: shrink db viewer sidebar nav icons from 20px to 16px

* style: shrink db viewer sidebar nav buttons to 32px (8px padding)

* style: make Tables panel title xs, regular weight, muted

* style: bump Tables panel title back to sm, keep regular weight and muted

* feat: export schema diagram as PNG/JPEG/SVG (entire schema or viewport)

* chore: lockfile for html-to-image

* fix: raise schema visualizer toolbar above legend so export menu isn't hidden

* feat: schema export via save dialog, transparent background option, save notification

* fix: render nothing in tab bar when no tabs are open

* style: reduce tab bar height from 40px to 36px

* style: reduce tab bar height to 32px

* style: revert tab bar height to 36px

* feat: split tab bar with fixed +Query and Changes actions on the right

* style: blue play-icon Query button in tab bar

* refactor: remove sidebar New Query button (now in tab bar)

* style: conditional bottom padding in sidebar toolbar when nothing is below

* feat: distinguish table and query tabs with icons

* style: tab icons follow active/inactive state, muted colors

* feat: query tab toolbar (run/format/dialect badge) + bare transparent editor

* style: blue rounded Run Query button in query toolbar

* feat: smart platform-aware shortcut tooltip on Run Query (⌘+⏎ / Ctrl+Enter)

* style: show only the shortcut in the Run Query tooltip

* fix: Cmd+Enter keybinding stale closure; add run pulse to query toolbar; bundle monaco locally (offline)

* feat: show placeholder text in empty query editor

* feat: SQL autocomplete — keywords + table names from active schema

* feat: per-table column autocomplete on 'table.' + docs update

* feat: query-variant result toolbar — export/refresh/columns left, smart-unit execution time right

* fix: populate execution_time_ms on query results so the toolbar can show time taken

* fix: re-measure monaco fonts after async font load to stop cursor drift

* feat: resizable + collapsible query results panel

* refactor: move results caret onto the resize handle (centered), bottom caret when collapsed

* style: thin drag strip with caret on its own centered pill

* refactor: remove Queue button from table toolbar (Changes lives in tab bar)

* style: changes button becomes bordered rounded icon with count badge

* docs: mark tab-bar Changes queue button in AGENTS.md and README

README.md

@@ -25,9 +25,9 @@ Most database GUI clients either lock essential productivity features behind pay
 | SSH tunneling | 🟡 (likely paid) | ✅ | 🟡 *Config UI done* |
 | OS credential vault | ✅ | ✅ | **Keychain / Secret Service** |
 | Workspace / folder hierarchy | ❌ | ❌ | **Multi-level tree + tags** |
-| Changes queue (stage & commit) | ❌ | ❌ | **✅ Queue → Commit All** |
-| Query history | ✅ (auto-saved) | ✅ | 🟡 *Upcoming* |
-| AI assistant | ✅ (BYO key) | ❌ (paid only) | ❌ |
+| Changes queue (stage & commit) | ❌ | ❌ | **✅ Queue → Commit All** (tab-bar **Changes** button with count badge toggles the commit panel) |
+| Query history | ✅ (auto-saved) | ✅ | 🟡 *Backend done, UI pending* |
+| AI assistant | ✅ (BYO key) | ❌ (paid only) | 🔮 *Planned — BYOK* |
 | Open source | ❌ | ✅ (GPLv3) | **✅ (MIT)** |
 | Desktop shell | Native webview | Electron (~250MB) | **Tauri 2.0 (~40MB)** |
 
@@ -96,10 +96,15 @@ Full tree-view navigation of all native PostgreSQL schema objects:
 - **Schema Visualizer (ER Diagram)** — interactive React Flow graph with dagre auto-layout, crow's foot notation (1:1, 1:N, N:M), color-coded relationships, schema selector, zoom controls, collapsible columns (PK/FK/unique-only), cross-schema FK support for PostgreSQL + SQLite
 
 ### SQL Editor & Query Workbench
-- **Multi-Tab Workspace** — unlimited named tabs, close with Cmd/Ctrl+W, session persistence across restarts
-- **Changes Queue** — queue INSERT/UPDATE/DELETE changes; preview before committing all
+- **Monaco SQL Editor** — lazy-loaded [Monaco Editor](https://microsoft.github.io/monaco-editor/) with SQL syntax highlighting, Cmd/Ctrl+Enter to run
+- **Custom Query Execution** — run arbitrary SQL on PostgreSQL + SQLite via the Rust `execute_query` command; subquery-wrapped pagination with automatic raw fallback for CTEs/multi-statement SQL
+- **Destructive Query Guard** — confirmation dialog for INSERT/UPDATE/DELETE/DROP/ALTER/TRUNCATE/CREATE/REPLACE before execution
+- **Query Tabs** — dedicated query tabs alongside table tabs, results rendered in the same virtualized data grid, close with Cmd/Ctrl+W
+- **SQL Autocomplete** — keyword + table suggestions from the active schema; typing `table.` suggests that table's columns (schema introspection, cached per schema)
+- **Multi-Tab Workspace** — unlimited named tabs, session persistence across restarts
+- **Changes Queue** — queue INSERT/UPDATE/DELETE changes; preview before committing all. The tab bar's **Changes** button (checklist icon + pending-count badge) toggles the bottom Commit All panel — the single entry point
 - **Smart Default Sort** — auto-detects `updated_at`, `created_at`, `_id` columns for logical initial sorting
-- *(Monaco Editor with SQL autocomplete, query history, and saved snippets — upcoming)*
+- *(query history UI dropdown, saved queries/snippets — upcoming)*
 
 ### Data Grid & Schema Browser
 - **Virtualized Grid** — row-level virtualization via `@tanstack/react-virtual` handles 100k+ rows
@@ -133,7 +138,7 @@ Full tree-view navigation of all native PostgreSQL schema objects:
 | **Frontend** | [React 19](https://react.dev) + [TypeScript](https://www.typescriptlang.org) | Component-based UI |
 | **Styling** | [Tailwind CSS](https://tailwindcss.com) | Utility-first, dark mode, glassmorphic design |
 | **State** | [Zustand](https://zustand.docs.pmnd.rs) / [Jotai](https://jotai.org) | Lightweight client-state for tabs, connections, queries |
-| **Code Editor** | *(planned)* [Monaco Editor](https://microsoft.github.io/monaco-editor/) | IDE-grade SQL editing with autocomplete (coming soon) |
+| **Code Editor** | [Monaco Editor](https://microsoft.github.io/monaco-editor/) | IDE-grade SQL editing with Cmd+Enter execution, lazy-loaded |
 | **Data Grid** | [TanStack Virtual](https://tanstack.com/virtual) | Virtualized row rendering for 100k+ rows |
 | **Local DB** | SQLite via [rusqlite](https://github.com/rusqlite/rusqlite) | User settings, saved queries, workspace state |
 
@@ -225,9 +230,11 @@ gridline/
 - **Phase 5 — Admin Tools** — `pg_dump`/`pg_restore` UI wrappers with real-time progress, DB-to-DB sync, backup/restore format selectors
 - **Phase 6 — Schema Visualizer** — Interactive ER diagram with React Flow + dagre, crow's foot notation, schema selector, legend, collapsible column views, PostgreSQL + SQLite support
 - **Home Screen & Organization** — Connection cards by folder, folders CRUD, tags CRUD with colors, global search (Cmd+K), import/export connections (JSON), bulk select/delete, DB type filter, demo SQLite database
+- **Query Editor (Core)** — Monaco SQL editor with Cmd+Enter execution, `execute_query` Rust command (PostgreSQL + SQLite, subquery pagination with raw fallback), query tabs in the DB viewer, destructive query confirmation dialog, `query_history` persistence backend
+- **Home Screen Filters** — Tag filter with OR semantics, folder cards matching tags or containing matching connections, DB type filter hiding empty folders, environment filter (All/Production/Staging/Development/None), global search across all folders with "Showing Search Results" breadcrumb + Clear
 
 ### 🟡 In Progress / Upcoming
-- **SQL Editor** — Monaco Editor integration with schema-aware SQL autocomplete, query history, saved queries
+- **Query Editor (Polish)** — SQL autocomplete (keywords, tables, and per-table columns), query history UI dropdown, saved queries
 - **SSH/SSL Runtime** — SSH tunnel via `ssh2` crate, SSL/TLS config passed to `sqlx`/`tokio-postgres`
 - **Inline Cell Editing** — Edit cells directly in the data grid
 - **Data Import** — CSV, JSON import with column mapping
@@ -238,6 +245,7 @@ gridline/
 - **Deeper PostgreSQL** — Indexes, constraints, materialized views, stored procedure view, user/role management
 - **Collaboration** — Team workspaces, shared connections, query sharing
 - **Notebook Reports** — SQL-backed markdown reports with embedded results
+- **AI Integration (BYOK)** — Bring-Your-Own-Key AI assistant: natural-language → SQL generation, query explanations, schema summaries, error suggestions. Key stored in OS keychain; only user's chosen provider sees SQL/text.
 
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