test: make unsafe test coercion explicit

Move test coercion out of a hidden global and require each test to import the helper so review tools and runtime scripts can see the unsafe boundary.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/ralph-loop/completion-promise-detector-test-input.test.ts

@@ -1,5 +1,6 @@
 /// <reference types="bun-types" />
 import type { PluginInput } from "@opencode-ai/plugin"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
 
 export type SessionMessage = {
 	info?: { role?: string }
@@ -16,7 +17,7 @@ export function createPluginInput(messages: SessionMessage[]): PluginInput {
 		$: {} as PluginInput["$"],
 	} as PluginInput
 
-	const messagesFunction = testCoerce<PluginInput["client"]["session"]["messages"]>(async () => ({ data: messages }))
+	const messagesFunction = unsafeTestValue<PluginInput["client"]["session"]["messages"]>(async () => ({ data: messages }))
 	pluginInput.client.session.messages = messagesFunction
 
 	return pluginInput

src/hooks/ralph-loop/reset-strategy-race-condition.test.ts

@@ -1,6 +1,7 @@
 /// <reference types="bun-types" />
 import { describe, expect, test } from "bun:test"
 import { createRalphLoopHook } from "./index"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
 
 function createDeferred(): {
   promise: Promise<void>
@@ -44,7 +45,7 @@ describe("ralph-loop reset strategy race condition", () => {
     const selectSessionDeferred = createDeferred()
 
     const hook = createRalphLoopHook(
-      testCoerce<Parameters<typeof createRalphLoopHook>[0]>({
+      unsafeTestValue<Parameters<typeof createRalphLoopHook>[0]>({
         directory: process.cwd(),
         client: {
           session: {

src/hooks/ralph-loop/ulw-loop-verification.test.ts

@@ -5,6 +5,7 @@ import { join } from "node:path"
 import { createRalphLoopHook } from "./index"
 import { ULTRAWORK_VERIFICATION_PROMISE } from "./constants"
 import { clearState, writeState } from "./storage"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
 
 describe("ulw-loop verification", () => {
 	const testDir = join(tmpdir(), `ulw-loop-verification-${Date.now()}`)
@@ -15,7 +16,7 @@ describe("ulw-loop verification", () => {
 	let oracleTranscriptPath: string
 
 	function createMockPluginInput() {
-		return testCoerce<Parameters<typeof createRalphLoopHook>[0]>({
+		return unsafeTestValue<Parameters<typeof createRalphLoopHook>[0]>({
 			client: {
 				session: {
 					promptAsync: async (opts: { path: { id: string }; body: { parts: Array<{ type: string; text: string }> } }) => {