Surface structured RCON failure reasons in the fleet UI

rconGetStatus previously collapsed at least five distinct failure modes
(no password, no port, socket error, timeout, bad reply) into a single
null return, so the UI could only say "rcon unreachable" — useless when
diagnosing a real Alcatraz outage.

Refactored to rconStatusResult() returning a discriminated union with a
RconFailure reason and human-facing detail. The worker persists these as
"<reason>:<detail>" in last_error (no schema change). /api/servers now
returns the derived endpoint (host:port) per server plus a top-level
integrations block (rcon/komodo configured, timeout, default host).

Server detail page gains an RCON diagnostic panel when health is not
online: shows the exact endpoint being dialed, integration status,
timeout, a color-coded reason tag, the detail, and a targeted fix hint.
Wrong-password replies are detected via "bad rcon" text in the print
body.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/lib/ui/rconError.ts

@@ -0,0 +1,43 @@
+import type { RconFailure } from '$ui/stores/servers.js';
+
+export interface DecodedRconError {
+    reason: RconFailure;
+    detail: string;
+}
+
+const KNOWN: RconFailure[] = ['no-config', 'no-port', 'send-error', 'timeout', 'bad-reply', 'no-players'];
+
+/**
+ * Decode the "<reason>:<detail>" string the worker persists into
+ * `servers.last_error`. Returns null for empty/legacy strings so the UI can
+ * fall back to a generic message.
+ */
+export function decodeRconError(raw: string | null | undefined): DecodedRconError | null {
+    if (!raw) return null;
+    const idx = raw.indexOf(':');
+    if (idx <= 0) return null;
+    const reason = raw.slice(0, idx);
+    if (!KNOWN.includes(reason as RconFailure)) return null;
+    return { reason: reason as RconFailure, detail: raw.slice(idx + 1).trim() };
+}
+
+/**
+ * Human-facing hint about how to fix each RCON failure. Kept short — the
+ * detail already carries the specifics (host, port, byte counts, etc.).
+ */
+export function rconFixHint(reason: RconFailure): string {
+    switch (reason) {
+        case 'no-config':
+            return 'Set RCON_PASSWORD in the container env and restart.';
+        case 'no-port':
+            return 'Set game_port on the server row, or configure Komodo so it can resolve the port.';
+        case 'send-error':
+            return 'DNS or route problem — check the RCON host is reachable from this container.';
+        case 'timeout':
+            return 'Plutonium is not replying on the resolved UDP port. Verify the server is running and the port matches.';
+        case 'bad-reply':
+            return 'Something is listening but not speaking Plutonium RCON. Check the port and password.';
+        case 'no-players':
+            return 'Reply parsed but no player table was found — likely a server-side dialect mismatch.';
+    }
+}

src/lib/ui/stores/servers.ts

@@ -10,6 +10,12 @@ export interface RosterPlayer {
 }
 
 export type Health = 'online' | 'stale' | 'offline';
+export type RconFailure = 'no-config' | 'no-port' | 'send-error' | 'timeout' | 'bad-reply' | 'no-players';
+
+export interface RconEndpoint {
+    host: string;
+    port: number;
+}
 
 export interface ServerStatus {
     server: string;
@@ -20,6 +26,8 @@ export interface ServerStatus {
     health: Health;
     lastSeenAt: string | null;
     lastError: string | null;
+    endpoint: RconEndpoint | null;
+    reason: RconFailure | null;
 }
 
 export const statusByServer = writable<Map<string, ServerStatus>>(new Map());