test: add regression coverage for sync plugin hooks

[Hona]

Summary

• add a regression test for synchronous plugin hooks in Plugin.trigger
• cover both synchronous and asynchronous experimental.chat.system.transform hooks
• verify with bun test \"test/plugin/trigger.test.ts\" from packages/opencode

[Copilot]

Pull request overview

Adds regression coverage in packages/opencode to ensure Plugin.trigger correctly handles both synchronous and asynchronous implementations of the experimental.chat.system.transform hook.

Changes:

• Adds a new plugin.trigger test suite validating sync hooks don’t crash and async hooks are awaited.
• Creates temporary per-test plugin projects via a generated opencode.json and plugin.ts.

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[Copilot]

The hook type for "experimental.chat.system.transform" expects input.model to be a full SDK Model (per the Hooks definition in packages/plugin/src/index.ts), but the test passes { providerID, modelID } cast as any. This makes the regression less representative and could hide failures in plugins that legitimately read fields like model.id; consider passing a more realistic Model shape (or resolving one via the same provider/model helper used in runtime) so the test matches real inputs.

[Copilot]

Same as above: this test passes a minimal { providerID, modelID } object cast as any for input.model, but the hook contract is SDK Model. Using a more realistic Model (or at least including the expected fields like model.id) will make this regression test closer to real Plugin.trigger usage and less brittle if hooks start depending on model properties.

[Copilot]

This test file redefines XDG_* and OPENCODE_TEST_HOME at module scope, but packages/opencode/bunfig.toml already preloads ./test/preload.ts which sets those env vars for the whole suite. Overriding them again adds global env churn and can cause cross-test interference if Bun executes files in parallel; consider relying on preload.ts (remove the XDG/OPENCODE_TEST_HOME rewrites + dynamic imports) or at least scope the env mutation to only what this test needs (e.g. just OPENCODE_DISABLE_DEFAULT_PLUGINS) with a tight beforeAll/afterAll.

Suggested change

	import { afterAll, afterEach, describe, expect, test } from "bun:test"
	import fs from "fs/promises"
	import os from "os"
	import path from "path"
	import { pathToFileURL } from "url"
	const env = {
	XDG_CONFIG_HOME: process.env.XDG_CONFIG_HOME,
	XDG_DATA_HOME: process.env.XDG_DATA_HOME,
	XDG_STATE_HOME: process.env.XDG_STATE_HOME,
	XDG_CACHE_HOME: process.env.XDG_CACHE_HOME,
	OPENCODE_TEST_HOME: process.env.OPENCODE_TEST_HOME,
	OPENCODE_DISABLE_DEFAULT_PLUGINS: process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS,
	}
	const root = await fs.mkdtemp(path.join(os.tmpdir(), "opencode-plugin-trigger-xdg-"))
	process.env.XDG_CONFIG_HOME = path.join(root, "config")
	process.env.XDG_DATA_HOME = path.join(root, "data")
	process.env.XDG_STATE_HOME = path.join(root, "state")
	process.env.XDG_CACHE_HOME = path.join(root, "cache")
	process.env.OPENCODE_TEST_HOME = path.join(root, "home")
	process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS = "1"
	const { Plugin } = await import("../../src/plugin/index")
	const { Instance } = await import("../../src/project/instance")
	afterEach(async () => {
	await Instance.disposeAll()
	})
	afterAll(async () => {
	for (const [key, value] of Object.entries(env)) {
	if (value === undefined) delete process.env[key]
	else process.env[key] = value
	}
	await fs.rm(root, { recursive: true, force: true })
	import { afterAll, afterEach, beforeAll, describe, expect, test } from "bun:test"
	import fs from "fs/promises"
	import os from "os"
	import path from "path"
	import { pathToFileURL } from "url"
	import { Plugin } from "../../src/plugin/index"
	import { Instance } from "../../src/project/instance"
	let originalDisableDefaultPlugins = process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS
	beforeAll(() => {
	originalDisableDefaultPlugins = process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS
	process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS = "1"
	})
	afterEach(async () => {
	await Instance.disposeAll()
	})
	afterAll(async () => {
	if (originalDisableDefaultPlugins === undefined) {
	delete process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS
	} else {
	process.env.OPENCODE_DISABLE_DEFAULT_PLUGINS = originalDisableDefaultPlugins
	}