Feature: Autocomplete / IntelliSense for SQL editing

[muk2]

Overview

Add schema-aware autocomplete to the SQL editor, providing suggestions for table names, column names, SQL keywords, and functions as the user types.

Goals

• Fast, responsive autocomplete popup triggered by typing
• Schema-aware: suggest real table/column names from the connected database
• Keyword/function completion for SQL syntax
• Contextual suggestions (e.g., after FROM suggest tables, after SELECT suggest columns)

---

Proposed Behavior

Trigger

• Autocomplete popup appears automatically after typing 2+ characters
• Can also be manually triggered with Ctrl+Space
• Dismiss with Esc

Suggestion Sources (priority order)

1. Table names — from loaded schema (qualified: schema.table)
2. Column names — from tables already referenced in the query
3. SQL keywords — SELECT, FROM, WHERE, JOIN, etc.
4. SQL functions — COUNT(), JSONB_BUILD_OBJECT(), etc.
5. SQL types — INTEGER, TIMESTAMPTZ, JSONB, etc.

Navigation

• Up/Down — navigate suggestions
• Tab or Enter — accept suggestion
• Esc — dismiss popup
• Continue typing to filter suggestions

Context Awareness

After typing...	Suggest...
FROM	Table names
JOIN	Table names
SELECT t.	Columns of table aliased as t
WHERE	Column names from referenced tables
::	Type names
Any partial word	Keywords, functions, tables matching prefix

---

Implementation Suggestions

• Add AutocompleteState struct to App (active, suggestions list, selected index, filter text)
• Build suggestion list from app.tables, app.schemas, SQL_KEYWORDS, SQL_FUNCTIONS, SQL_TYPES
• Render as a floating popup widget below the cursor position
• Use case-insensitive prefix matching for filtering
• Cache column lists per table to avoid repeated DB queries

UI Mockup

SELECT u.|
         ┌──────────────────┐
         │ id          INT4 │
         │ name        TEXT │
         │ email       TEXT │
         │ created_at  TSTZ │
         └──────────────────┘

Definition of Done

• Autocomplete popup renders correctly below cursor
• Table and column names from schema appear as suggestions
• SQL keywords and functions appear as suggestions
• Typing filters the list in real-time
• Tab/Enter inserts the selected suggestion
• Esc dismisses the popup
• No noticeable input lag when popup is active