diff --git a/src/agent/tools/memory.rs b/src/agent/tools/memory.rs
index 9abc712..5c673cb 100644
--- a/src/agent/tools/memory.rs
+++ b/src/agent/tools/memory.rs
@@ -245,11 +245,13 @@ fn output(args: &serde_json::Value) -> Result<String> {
         anyhow::bail!("invalid output key: {}", key);
     }
     let value = get_str(args, "value")?;
-    let dir = std::env::var("POC_AGENT_OUTPUT_DIR")
-        .map_err(|_| anyhow::anyhow!("no output directory set"))?;
-    let path = std::path::Path::new(&dir).join(key);
-    std::fs::write(&path, value)
-        .with_context(|| format!("writing output {}", path.display()))?;
+    // Write to disk if output dir is set (subprocess agents),
+    // otherwise just return success (forked agents extract from AST)
+    if let Ok(dir) = std::env::var("POC_AGENT_OUTPUT_DIR") {
+        let path = std::path::Path::new(&dir).join(&key);
+        std::fs::write(&path, &value)
+            .with_context(|| format!("writing output {}", path.display()))?;
+    }
     Ok(format!("{}: {}", key, value))
 }