diff --git a/src/shared/legacy-plugin-warning.test.ts b/src/shared/legacy-plugin-warning.test.ts
index adbfcfa8b..3bc16c3b1 100644
--- a/src/shared/legacy-plugin-warning.test.ts
+++ b/src/shared/legacy-plugin-warning.test.ts
@@ -6,40 +6,22 @@ import { checkForLegacyPluginEntry } from "./legacy-plugin-warning"
 
 describe("checkForLegacyPluginEntry", () => {
   let testConfigDir = ""
-  let originalXdgConfigHome: string | undefined
-  let originalOpenCodeConfigDir: string | undefined
 
   beforeEach(() => {
-    originalXdgConfigHome = process.env.XDG_CONFIG_HOME
-    originalOpenCodeConfigDir = process.env.OPENCODE_CONFIG_DIR
     testConfigDir = join(tmpdir(), `omo-legacy-check-${Date.now()}-${Math.random().toString(36).slice(2)}`)
-    mkdirSync(join(testConfigDir, "opencode"), { recursive: true })
-    process.env.XDG_CONFIG_HOME = testConfigDir
-    delete process.env.OPENCODE_CONFIG_DIR
+    mkdirSync(testConfigDir, { recursive: true })
   })
 
   afterEach(() => {
-    if (originalXdgConfigHome === undefined) {
-      delete process.env.XDG_CONFIG_HOME
-    } else {
-      process.env.XDG_CONFIG_HOME = originalXdgConfigHome
-    }
-
-    if (originalOpenCodeConfigDir === undefined) {
-      delete process.env.OPENCODE_CONFIG_DIR
-    } else {
-      process.env.OPENCODE_CONFIG_DIR = originalOpenCodeConfigDir
-    }
-
     rmSync(testConfigDir, { recursive: true, force: true })
   })
 
   it("detects a bare legacy plugin entry", () => {
     // given
-    writeFileSync(join(testConfigDir, "opencode", "opencode.json"), JSON.stringify({ plugin: ["oh-my-opencode"] }, null, 2))
+    writeFileSync(join(testConfigDir, "opencode.json"), JSON.stringify({ plugin: ["oh-my-opencode"] }, null, 2))
 
     // when
-    const result = checkForLegacyPluginEntry()
+    const result = checkForLegacyPluginEntry(testConfigDir)
 
     // then
     expect(result.hasLegacyEntry).toBe(true)
@@ -49,10 +31,10 @@ describe("checkForLegacyPluginEntry", () => {
 
   it("detects a version-pinned legacy plugin entry", () => {
     // given
-    writeFileSync(join(testConfigDir, "opencode", "opencode.json"), JSON.stringify({ plugin: ["oh-my-opencode@3.10.0"] }, null, 2))
+    writeFileSync(join(testConfigDir, "opencode.json"), JSON.stringify({ plugin: ["oh-my-opencode@3.10.0"] }, null, 2))
 
     // when
-    const result = checkForLegacyPluginEntry()
+    const result = checkForLegacyPluginEntry(testConfigDir)
 
     // then
     expect(result.hasLegacyEntry).toBe(true)
@@ -62,10 +44,10 @@ describe("checkForLegacyPluginEntry", () => {
 
   it("does not flag a canonical plugin entry", () => {
     // given
-    writeFileSync(join(testConfigDir, "opencode", "opencode.json"), JSON.stringify({ plugin: ["oh-my-openagent"] }, null, 2))
+    writeFileSync(join(testConfigDir, "opencode.json"), JSON.stringify({ plugin: ["oh-my-openagent"] }, null, 2))
 
     // when
-    const result = checkForLegacyPluginEntry()
+    const result = checkForLegacyPluginEntry(testConfigDir)
 
     // then
     expect(result.hasLegacyEntry).toBe(false)
@@ -75,10 +57,10 @@ describe("checkForLegacyPluginEntry", () => {
 
   it("detects legacy entries in quoted jsonc config", () => {
     // given
-    writeFileSync(join(testConfigDir, "opencode", "opencode.jsonc"), '{\n  "plugin": ["oh-my-opencode"]\n}\n')
+    writeFileSync(join(testConfigDir, "opencode.jsonc"), '{\n  "plugin": ["oh-my-opencode"]\n}\n')
 
     // when
-    const result = checkForLegacyPluginEntry()
+    const result = checkForLegacyPluginEntry(testConfigDir)
 
     // then
     expect(result.hasLegacyEntry).toBe(true)
@@ -86,8 +68,10 @@ describe("checkForLegacyPluginEntry", () => {
   })
 
   it("returns no warning data when config is missing", () => {
+    // given — empty dir, no config files
+
     // when
-    const result = checkForLegacyPluginEntry()
+    const result = checkForLegacyPluginEntry(testConfigDir)
 
     // then
     expect(result.hasLegacyEntry).toBe(false)
diff --git a/src/shared/legacy-plugin-warning.ts b/src/shared/legacy-plugin-warning.ts
index 5e97a764f..c8a7e94df 100644
--- a/src/shared/legacy-plugin-warning.ts
+++ b/src/shared/legacy-plugin-warning.ts
@@ -1,4 +1,5 @@
 import { existsSync, readFileSync } from "node:fs"
+import { join } from "node:path"
 
 import { parseJsoncSafe } from "./jsonc-parser"
 import { getOpenCodeConfigPaths } from "./opencode-config-dir"
@@ -14,7 +15,15 @@ export interface LegacyPluginCheckResult {
   legacyEntries: string[]
 }
 
-function getOpenCodeConfigPath(): string | null {
+function getOpenCodeConfigPath(overrideConfigDir?: string): string | null {
+  if (overrideConfigDir) {
+    const jsonPath = join(overrideConfigDir, "opencode.json")
+    const jsoncPath = join(overrideConfigDir, "opencode.jsonc")
+    if (existsSync(jsoncPath)) return jsoncPath
+    if (existsSync(jsonPath)) return jsonPath
+    return null
+  }
+
   const { configJsonc, configJson } = getOpenCodeConfigPaths({ binary: "opencode", version: null })
 
   if (existsSync(configJsonc)) return configJsonc
@@ -30,8 +39,8 @@ function isCanonicalPluginEntry(entry: string): boolean {
   return entry === PLUGIN_NAME || entry.startsWith(`${PLUGIN_NAME}@`)
 }
 
-export function checkForLegacyPluginEntry(): LegacyPluginCheckResult {
-  const configPath = getOpenCodeConfigPath()
+export function checkForLegacyPluginEntry(overrideConfigDir?: string): LegacyPluginCheckResult {
+  const configPath = getOpenCodeConfigPath(overrideConfigDir)
   if (!configPath) {
     return { hasLegacyEntry: false, hasCanonicalEntry: false, legacyEntries: [] }
   }