attach-db

name	attach-db
description	Attach a DuckDB database file for use with /duckdb-skills:query. Explores the schema (tables, columns, row counts) and writes a SQL state file so subsequent queries can restore this session automatically via duckdb -init.
argument-hint	<path-to-database.duckdb>
allowed-tools	Bash

You are helping the user attach a DuckDB database file for interactive querying.

Database path given: $0

Follow these steps in order, stopping and reporting clearly if any step fails.

State file convention: see the "Resolve state directory" section below. All skills share a single state.sql file per project. Once resolved, any skill can use it with duckdb -init "$STATE_DIR/state.sql" -c "<QUERY>".

Step 1 — Resolve the database path

If $0 is a relative path, resolve it against $PWD to get an absolute path (RESOLVED_PATH).

RESOLVED_PATH="$(cd "$(dirname "$0")" 2>/dev/null && pwd)/$(basename "$0")"

Check the file exists:

test -f "$RESOLVED_PATH"

• File exists -> continue to Step 2.
• File not found -> ask the user if they want to create a new empty database (DuckDB creates the file on first write). If yes, continue. If no, stop.

Step 2 — Check DuckDB is installed

command -v duckdb

If not found, delegate to /duckdb-skills:install-duckdb and then continue.

Step 3 — Validate the database

duckdb "$RESOLVED_PATH" -c "PRAGMA version;"

• Success -> continue.
• Failure -> report the error clearly (e.g. corrupt file, not a DuckDB database) and stop.

Step 4 — Explore the schema

First, list all tables:

duckdb "$RESOLVED_PATH" -csv -c "
SELECT table_name, estimated_size
FROM duckdb_tables()
ORDER BY table_name;
"

If the database has no tables, note that it is empty and skip to Step 5.

For each table discovered (up to 20), run:

duckdb "$RESOLVED_PATH" -csv -c "
DESCRIBE <table_name>;
SELECT count() AS row_count FROM <table_name>;
"

Collect the column definitions and row counts for the summary.

Step 5 — Resolve the state directory

Check if a state file already exists in either location:

# Option 1: in the project directory
test -f .duckdb-skills/state.sql && STATE_DIR=".duckdb-skills"

# Option 2: in the home directory, scoped by project root path
PROJECT_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || echo "$PWD")"
PROJECT_ID="$(echo "$PROJECT_ROOT" | tr '/' '-')"
test -f "$HOME/.duckdb-skills/$PROJECT_ID/state.sql" && STATE_DIR="$HOME/.duckdb-skills/$PROJECT_ID"

If neither exists, ask the user:

Where would you like to store the DuckDB session state for this project?

1. In the project directory (.duckdb-skills/state.sql) — colocated with the project, easy to find. You can choose to gitignore it.
2. In your home directory (~/.duckdb-skills/<project-id>/state.sql) — keeps the project directory clean.

Based on their choice:

Option 1:

STATE_DIR=".duckdb-skills"
mkdir -p "$STATE_DIR"

Then ask: "Would you like to gitignore .duckdb-skills/?" If yes:

echo '.duckdb-skills/' >> .gitignore

Option 2:

PROJECT_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || echo "$PWD")"
PROJECT_ID="$(echo "$PROJECT_ROOT" | tr '/' '-')"
STATE_DIR="$HOME/.duckdb-skills/$PROJECT_ID"
mkdir -p "$STATE_DIR"

Step 6 — Append to the state file

state.sql is a shared, accumulative init file used by all duckdb-skills. It may already contain macros, LOAD statements, secrets, or other ATTACH statements written by other skills. Never overwrite it — always check for duplicates and append.

Derive the database alias from the filename without extension (e.g. my_data.duckdb → my_data). Check if this ATTACH already exists:

grep -q "ATTACH.*RESOLVED_PATH" "$STATE_DIR/state.sql" 2>/dev/null

If not already present, append:

cat >> "$STATE_DIR/state.sql" <<'STATESQL'
ATTACH IF NOT EXISTS 'RESOLVED_PATH' AS my_data;
USE my_data;
STATESQL

Replace RESOLVED_PATH and my_data with the actual values. If the alias would conflict with an existing one in the file, ask the user for a name.

Step 7 — Verify the state file works

duckdb -init "$STATE_DIR/state.sql" -c "SHOW TABLES;"

If this fails, fix the state file and retry.

Step 8 — Report

Summarize for the user:

• Database path: the resolved absolute path
• Alias: the database alias used in the state file
• State file: the resolved STATE_DIR/state.sql path
• Tables: name, column count, row count for each table (or note the DB is empty)
• Confirm the database is now active for /duckdb-skills:query

If the database is empty, suggest creating tables or importing data.