Database Targets

nah can auto-allow db_write operations to specific databases when the target matches a configured allowlist. This requires opting in with a context policy.

Supported databases

Currently PostgreSQL (psql) and Snowflake (snowsql, snow sql, MCP). Target configs are shared across both — there's no way to scope a db_targets entry to a single database engine.

Setup

Two-step activation:

# ~/.config/nah/config.yaml
actions:
  db_write: context          # 1. route db_write through context resolver

db_targets:                   # 2. define allowed targets
  - database: ANALYTICS_DEV
    schema: PUBLIC
  - database: STAGING

Without db_write: context, the default policy (ask) applies to all database writes regardless of db_targets.

Target matching

• Case-insensitive -- analytics_dev matches ANALYTICS_DEV
• Wildcard -- database: "*" matches any database
• Schema optional -- omitting schema matches any schema in that database

db_targets:
  - database: "*"             # allow all databases (not recommended)
    schema: PUBLIC
  - database: DEV_DB          # any schema in DEV_DB
  - database: PROD
    schema: ANALYTICS         # only PROD.ANALYTICS

Target extraction

nah extracts database targets from CLI flags and MCP tool input.

CLI commands

Command	Database flag	Schema flag
psql	-d / --dbname / connection URL	(not extracted)
snowsql	-d / --dbname	-s / --schemaname
snow sql	--database	--schema

# psql: database from -d flag
psql -d analytics_dev -c "DROP TABLE old_data"

# psql: database from connection URL
psql postgresql://localhost/analytics_dev -c "DROP TABLE old_data"

# snowsql: database + schema
snowsql -d ANALYTICS_DEV -s PUBLIC -q "INSERT INTO ..."

# snow sql: long-form flags
snow sql --database ANALYTICS_DEV --schema PUBLIC -q "INSERT INTO ..."

MCP tools

For MCP tools (mcp__*), nah extracts database and schema from the tool's tool_input fields:

{
  "tool_name": "mcp__snowflake__execute_query",
  "tool_input": {
    "database": "ANALYTICS_DEV",
    "schema": "PUBLIC",
    "query": "INSERT INTO events ..."
  }
}

Decision flow

1. Command classified as db_write
2. Policy is context → context resolver runs
3. Target extracted from CLI flags or tool input
4. Target checked against db_targets allowlist
5. Match → allow / No match → ask / No target found → ask

Global config only

db_targets is only accepted in ~/.config/nah/config.yaml. Project config cannot modify it.