wp db query under SQLite: Fatal — Undefined constant "DB_HOST"

[chubes4]

Repro

In a Studio site backed by Playground + SQLite drop-in:

wp db query "SELECT option_name FROM wp_options LIMIT 1"

Fatal:

Fatal error: Uncaught Error: Undefined constant "DB_HOST" in
phar:///tmp/wp-cli.phar/vendor/wp-cli/db-command/src/DB_Command.php:1798

Cause

wp db shells out to the mysql binary. The Playground SQLite stack defines no DB_HOST/DB_USER/DB_PASSWORD constants, and mysql isn't available in the runtime anyway. db-command tries to build a mysql --no-defaults … invocation using those constants and crashes before the missing-binary check.

Impact

Any agent or script that falls back to wp db query … for ad-hoc SQL against site state fatals. Affects anyone running Data Machine or Intelligence on Studio/Playground. Workaround (wp eval '$wpdb->get_results(...)') works but isn't obvious, especially to tooling that auto-reaches for wp db.

Suggested fix

Two reasonable options:

1. In the SQLite integration: short-circuit wp db subcommands with a clean "not available on SQLite — use wp eval or open the SQLite file directly" error. Graceful failure beats a fatal.
2. Predefine stub DB_* constants early in Playground's WP bootstrap so db-command at least errors with "mysql binary not found" instead of "undefined constant". Less clean but one-line.

Ideally route through (1) — wp db under SQLite should be a no-op with a clear message, not a crash.

Environment

• Playground dev/combined-fixes + Studio dev/combined-fixes (Studio apps/cli wired to v3.1.20 tarballs from a local self-host)
• wp-cli 2.12.0 (from the Playground-bundled wp-cli.phar)
• PHP 8.3, SQLite integration via MDI's db.php drop-in (behavior is the same with stock sqlite-database-integration drop-in per earlier observation)

[chubes4]

Closing as duplicate of #1618 — that's the umbrella for wp-cli commands that don't work under Playground's SQLite stack, and wp db query is explicitly listed there.

Root cause lives in wp-cli/db-command, not Playground:

• DB_Command::run() reads DB_HOST/DB_USER/DB_PASSWORD as bare constants, which PHP 8+ fatals on when those constants aren't defined at after_wp_config_load time.
• Add SQLite compatibility to wp db commands wp-cli/db-command#299 (merged, v2.1.5) adds SQLite detection and routes query, create, drop, reset, export, import, size through a dedicated SQLite trait, avoiding the bare-constant read path entirely. Playground just needs to pick up db-command ≥ 2.1.5 in its bundled wp-cli.phar.
• Add wpdb fallback for wp db query, wp db import, wp db drop, and wp db reset when mysql/mariadb binary is unavailable wp-cli/db-command#320 (draft) is a broader follow-up adding a $wpdb fallback when the mysql/mariadb binary is unavailable, which is architecturally the more robust path and has ongoing discussion about how query should behave to avoid bypassing the SQLite driver.

Apologies for the noise — should have found #1618 before filing.