diff --git a/packages/coding-agent/test/discovery/claude-commands.test.ts b/packages/coding-agent/test/discovery/claude-commands.test.ts
index 30774cf15..461c7ac8d 100644
--- a/packages/coding-agent/test/discovery/claude-commands.test.ts
+++ b/packages/coding-agent/test/discovery/claude-commands.test.ts
@@ -25,6 +25,7 @@ describe("Claude Code slash command discovery", () => {
 		resetSettingsForTest();
 		originalHome = process.env.HOME;
 		originalClaudeConfigDir = process.env.CLAUDE_CONFIG_DIR;
+		delete process.env.CLAUDE_CONFIG_DIR;
 		root = await fs.mkdtemp(path.join(os.tmpdir(), "omp-claude-commands-"));
 		home = path.join(root, "home");
 		project = path.join(root, "project");
diff --git a/packages/coding-agent/test/discovery/claude-plugins.test.ts b/packages/coding-agent/test/discovery/claude-plugins.test.ts
index f7ab94501..aa28719dd 100644
--- a/packages/coding-agent/test/discovery/claude-plugins.test.ts
+++ b/packages/coding-agent/test/discovery/claude-plugins.test.ts
@@ -86,6 +86,7 @@ describe("listClaudePluginRoots", () => {
 		originalOmpProfileEnv = process.env.OMP_PROFILE;
 		originalPiProfileEnv = process.env.PI_PROFILE;
 		originalClaudeConfigDir = process.env.CLAUDE_CONFIG_DIR;
+		delete process.env.CLAUDE_CONFIG_DIR;
 		tempDir = await fs.mkdtemp(path.join(os.tmpdir(), "claude-plugins-test-"));
 		testAgentDir = await fs.mkdtemp(path.join(os.tmpdir(), "claude-plugins-test-agent-"));
 		process.env.HOME = tempDir;
@@ -1378,15 +1379,19 @@ describe("listClaudePluginRoots", () => {
 
 describe("discoverAgents plugin precedence", () => {
 	let tempDir: string;
+	let originalClaudeConfigDir: string | undefined;
 
 	beforeEach(async () => {
 		clearClaudePluginRootsCache();
 		clearFsCache();
+		originalClaudeConfigDir = process.env.CLAUDE_CONFIG_DIR;
+		delete process.env.CLAUDE_CONFIG_DIR;
 		tempDir = await fs.mkdtemp(path.join(os.tmpdir(), "claude-plugins-precedence-test-"));
 	});
 
 	afterEach(async () => {
 		clearClaudePluginRootsCache();
+		restoreEnvValue("CLAUDE_CONFIG_DIR", originalClaudeConfigDir);
 		await removeWithRetries(tempDir);
 	});
 
diff --git a/packages/coding-agent/test/foreign-session-stores.test.ts b/packages/coding-agent/test/foreign-session-stores.test.ts
index 4b92d066c..e3af3e875 100644
--- a/packages/coding-agent/test/foreign-session-stores.test.ts
+++ b/packages/coding-agent/test/foreign-session-stores.test.ts
@@ -17,6 +17,7 @@ let originalClaudeConfigDir: string | undefined;
 beforeEach(async () => {
 	tempRoot = await fs.mkdtemp(path.join(os.tmpdir(), "omp-foreign-sessions-"));
 	originalClaudeConfigDir = process.env.CLAUDE_CONFIG_DIR;
+	delete process.env.CLAUDE_CONFIG_DIR;
 });
 
 afterEach(async () => {