diff --git a/server/src/llm/providers/claude_code.rs b/server/src/llm/providers/claude_code.rs
index b3fd1e4..a945af9 100644
--- a/server/src/llm/providers/claude_code.rs
+++ b/server/src/llm/providers/claude_code.rs
@@ -120,6 +120,7 @@ impl ClaudeCodeProvider {
             .map_err(|e| format!("PTY task panicked: {e}"))??;
 
         let captured_session_id = sid_rx.await.ok();
+        slog!("[pty-debug] RECEIVED session_id: {:?}", captured_session_id);
         let structured_messages: Vec<Message> = msg_rx.try_iter().collect();
 
         Ok(ClaudeCodeResult {
@@ -346,6 +347,7 @@ fn process_json_event(
     // Capture session_id from the first event that carries it
     if let Some(tx) = sid_tx.take() {
         if let Some(sid) = json.get("session_id").and_then(|s| s.as_str()) {
+            slog!("[pty-debug] CAPTURED session_id: {}", sid);
             let _ = tx.send(sid.to_string());
         } else {
             *sid_tx = Some(tx);
diff --git a/server/src/matrix/bot.rs b/server/src/matrix/bot.rs
index 36d9b6a..b65c830 100644
--- a/server/src/matrix/bot.rs
+++ b/server/src/matrix/bot.rs
@@ -881,6 +881,7 @@ async fn handle_message(
             } else {
                 remaining
             };
+            slog!("[matrix-bot] session_id from chat_stream: {:?}", session_id);
             (reply, session_id)
         }
         Err(e) => {
@@ -903,6 +904,7 @@ async fn handle_message(
         let conv = guard.entry(room_id).or_default();
 
         // Store the session ID so the next turn uses --resume.
+        slog!("[matrix-bot] storing session_id: {:?} (was: {:?})", new_session_id, conv.session_id);
         if new_session_id.is_some() {
             conv.session_id = new_session_id;
         }
@@ -919,13 +921,12 @@ async fn handle_message(
         });
 
         // Trim to the configured maximum, dropping the oldest entries first.
-        // When trimming occurs, clear the session ID so the next turn starts
-        // a fresh Claude Code session (the old session's context would be
-        // stale since we've dropped entries from our tracking).
+        // The session_id is preserved: Claude Code's --resume loads the full
+        // conversation from its own session transcript on disk, so trimming
+        // our local tracking doesn't affect the LLM's context.
         if conv.entries.len() > ctx.history_size {
             let excess = conv.entries.len() - ctx.history_size;
             conv.entries.drain(..excess);
-            conv.session_id = None;
         }
 
         // Persist to disk so history survives server restarts.