Add Bun-first SQLite runtime adapter for Node-targeted bundles

[Copilot]

Node-targeted consumers could still fail at runtime because the package statically imported bun:sqlite, which survives bundling into Node CLI artifacts. This change keeps Bun as the primary runtime while allowing Node consumers to load the package without pulling in bun:* imports at module initialization.

• Runtime backend selection

  • Replace the top-level bun:sqlite import with a runtime-selected SQLite adapter.
  • Prefer bun:sqlite on Bun.
  • Fall back to built-in node:sqlite on supported Node runtimes.

• Engine/store lifecycle

  • Make SecretStore.open() asynchronous so the backend can be resolved lazily.
  • Update engine call sites to await store initialization without changing the public SecretsEngine API.

• Packaging and runtime expectations

  • Build the published package for a Node target so bundled consumers do not retain a hard bun:sqlite dependency.
  • Document Bun-first/Node-compatible runtime behavior and the Node requirement for built-in SQLite support.

• Regression coverage

  • Add a bundle-level regression test that builds a Node-targeted consumer and executes it under Node to verify the package no longer fails with ERR_UNSUPPORTED_ESM_URL_SCHEME.

import { SecretsEngine } from "@wgtechlabs/secrets-engine";

const secrets = await SecretsEngine.open({ path: "/tmp/secrets-store" });
await secrets.set("cli.version", "1.0.0");

console.log(await secrets.get("cli.version"));

await secrets.close();

Original prompt

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This section details on the original issue you should resolve

<issue_title>Node-targeted npm CLIs fail because the package imports bun:sqlite</issue_title>
<issue_description>## Summary
Using @wgtechlabs/secrets-engine in a package that is built for Node and published to npm can fail at runtime because the package imports bun:sqlite.

In practice this makes the package Bun-only for bundled Node CLI releases, even when the consumer application itself targets Node.

Repro

Consumer build:

bun build src/index.ts --outfile dist/index.js --target node
node dist/index.js --version

Actual result

Node fails during module loading with:

Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only URLs with a scheme in: file, data, and node are supported by the default ESM loader. Received protocol 'bun:'

Why this matters

I hit this in a released npm CLI because Bun bundled the dependency graph into a Node-targeted artifact, and the resulting build still contained bun:sqlite imports.

That means the package is not currently safe to consume from a published Node CLI unless the consumer is also effectively Bun-only.

Expected result

One of these should happen:

1. The package provides a Node-safe backend or conditional runtime adapter.
2. The package clearly documents that it is Bun-only.
3. The package exposes a storage abstraction that allows Node consumers to avoid bundling bun:* imports.

Notes

I am happy to help test a fix from the consumer side.
</issue_description>

<agent_instructions>Let's add support to both Node and Bun but make the bun the primary support.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Node-targeted npm CLIs fail because the package imports bun:sqlite #4

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[Copilot]

Pull request overview

Adds a runtime-selected SQLite adapter so @wgtechlabs/secrets-engine can be bundled for (and executed on) Node without a hard bun:sqlite import at module init time, while keeping Bun as the preferred runtime.

Changes:

• Replace static bun:sqlite import with a lazy runtime adapter that prefers Bun and falls back to node:sqlite.
• Make SecretStore.open() async and update engine call sites to await store initialization.
• Update packaging/metadata + docs, and add a regression test that bundles a Node-targeted consumer and runs it under Node.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/engine.test.ts	Adds a bundle-level regression test that builds for target: "node" and executes via node
src/store.ts	Introduces runtime-selected SQLite opener (Bun-first, Node fallback) and makes SecretStore.open() async
src/engine.ts	Awaits async store initialization in engine open + detached-store cleanup
package.json	Builds dist with --target node and declares engines.node >= 22.5.0
README.md	Documents Bun-first / Node-compatible behavior and Node’s built-in sqlite requirement

[warengonzaga]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied the thread feedback in 58939a9. The Node-targeted bundle regression now skips when the local node runtime cannot import node:sqlite, so Node 20 CI won’t fail while newer Node runtimes still exercise the path.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

[warengonzaga]

@copilot apply code review as necessary as possible.

[Copilot]

@copilot apply code review as necessary as possible.

Applied the remaining review fixes in 87f86ba. CI now uses Node 22.5.0 so the Node SQLite regression runs on a supported runtime, and the generated bundle now uses .mjs so Node exercises the ESM loader path.