render: mark node as seen when POC_SESSION_ID is set

When poc-memory render is called inside a Claude session, add the
key to the seen set so the surface agent knows it's been shown.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/cli/node.rs

@@ -248,6 +248,22 @@ pub fn cmd_render(key: &[String]) -> Result<(), String> {
     let rendered = render_node(&store, &bare)
         .ok_or_else(|| format!("Node not found: {}", bare))?;
     print!("{}", rendered);
+
+    // Mark as seen if we're inside a Claude session
+    if let Ok(session_id) = std::env::var("POC_SESSION_ID") {
+        if !session_id.is_empty() {
+            let state_dir = std::path::PathBuf::from("/tmp/claude-memory-search");
+            let seen_path = state_dir.join(format!("seen-{}", session_id));
+            if let Ok(mut f) = std::fs::OpenOptions::new()
+                .create(true).append(true).open(seen_path)
+            {
+                use std::io::Write;
+                let ts = chrono::Local::now().format("%Y-%m-%dT%H:%M:%S");
+                let _ = writeln!(f, "{}\t{}", ts, bare);
+            }
+        }
+    }
+
     Ok(())
 }