diff --git a/packages/adapters/opencode-local/src/server/execute.ts b/packages/adapters/opencode-local/src/server/execute.ts
index c3d5d591..06f6478e 100644
--- a/packages/adapters/opencode-local/src/server/execute.ts
+++ b/packages/adapters/opencode-local/src/server/execute.ts
@@ -108,7 +108,11 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
   if (!hasExplicitApiKey && authToken) {
     env.PAPERCLIP_API_KEY = authToken;
   }
-  const runtimeEnv = ensurePathInEnv({ ...process.env, ...env });
+  const runtimeEnv = Object.fromEntries(
+    Object.entries(ensurePathInEnv({ ...process.env, ...env })).filter(
+      (entry): entry is [string, string] => typeof entry[1] === "string",
+    ),
+  );
   await ensureCommandResolvable(command, cwd, runtimeEnv);
 
   await ensureOpenCodeModelConfiguredAndAvailable({
@@ -216,7 +220,7 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
 
     const proc = await runChildProcess(runId, command, args, {
       cwd,
-      env,
+      env: runtimeEnv,
       stdin: prompt,
       timeoutSec,
       graceSec,