Add SSE cleanup

src/server.ts

@@ -30,6 +30,8 @@ import type {
 const sseClients = new Set<ReadableStreamDefaultController<string>>();
 const sessionWebSockets = new Map<number, ServerWebSocket<SessionData>>();
 const sessionStates = new Map<number, SessionState>();
+// Buffer for incomplete ANSI sequences per session to avoid leaking partial control codes
+const ansiCarryovers = new Map<number, string>();
 
 interface SessionData {
   deviceId: number;
@@ -79,6 +81,55 @@ function broadcastSSE(event: SSEEvent): void {
   }
 }
 
+// Detect and split any incomplete ANSI control sequence at the end of a chunk.
+// Returns [body, carry] where carry should be saved and prepended to the next chunk.
+function splitAnsiCarryover(chunk: string): [string, string] {
+  if (!chunk) return ["", ""];
+
+  const ESC = 0x1b;
+  const len = chunk.length;
+
+  // If last char is ESC, entire ESC starts a sequence we can't complete
+  if (chunk.charCodeAt(len - 1) === ESC) {
+    return [chunk.slice(0, -1), "\x1b"];
+  }
+
+  // Search from the last ESC backwards for a potentially incomplete sequence
+  for (let i = len - 2; i >= 0; i--) {
+    if (chunk.charCodeAt(i) !== ESC) continue;
+    const next = chunk[i + 1];
+    // OSC: ESC ] ... (terminated by BEL 0x07 or ST = ESC \
+    if (next === "]") {
+      const tail = chunk.slice(i + 2);
+      const hasBEL = tail.indexOf("\x07") !== -1;
+      const hasST = tail.indexOf("\x1b\\") !== -1;
+      if (!hasBEL && !hasST) {
+        return [chunk.slice(0, i), chunk.slice(i)];
+      }
+      // else complete; continue scanning
+      continue;
+    }
+    // CSI: ESC [ params final — ensure we have a final byte 0x40-0x7E
+    if (next === "[") {
+      let j = i + 2;
+      while (j < len && /[0-9;?]/.test(chunk[j] || "")) j++;
+      // If we reached end without a final byte, it's incomplete
+      if (j >= len) {
+        return [chunk.slice(0, i), chunk.slice(i)];
+      }
+      // Final byte exists at chunk[j]; sequence complete
+      continue;
+    }
+    // DCS/PM/APC and other ESC-prefixed two-char intros — if ESC is near end and likely incomplete, carry
+    // If ESC is the penultimate and we're at end, treat as incomplete unknown sequence
+    if (i >= len - 2) {
+      return [chunk.slice(0, i), chunk.slice(i)];
+    }
+    // Otherwise, unknown but complete; continue
+  }
+  return [chunk, ""];
+}
+
 // Initialize database
 const port = Number.parseInt(process.env.PORT || "7200", 10);
 initDb();
@@ -484,11 +535,25 @@ const server = Bun.serve<SessionData>({
 
         // Handle output message
         if (msg.type === "output") {
-          appendOutput(ws.data.sessionId, msg.data); // Store raw ANSI
+          const sessionId = ws.data.sessionId;
+          // Join with any saved carryover from previous chunk
+          const prevCarry = ansiCarryovers.get(sessionId) || "";
+          const combined = prevCarry ? prevCarry + msg.data : msg.data;
+          // Determine if new tail is an incomplete control sequence and split
+          const [body, carry] = splitAnsiCarryover(combined);
+          if (carry) {
+            ansiCarryovers.set(sessionId, carry);
+          } else if (prevCarry) {
+            // Clear carry if previously set and now resolved
+            ansiCarryovers.delete(sessionId);
+          }
+
+          appendOutput(sessionId, body); // Store raw ANSI without trailing incomplete fragment
+
           broadcastSSE({
             type: "output",
-            session_id: ws.data.sessionId,
-            data: ansiToHtml(msg.data), // Parse for display
+            session_id: sessionId,
+            data: ansiToHtml(body), // Parse for display
           });
           return;
         }