Apply selected server maps automatically without config overlays

src/lib/server/fleet/config-compose.ts

@@ -14,6 +14,8 @@
 //   - Line endings default to \n for the composed output. Baseline CRLF is
 //     preserved if the baseline uses CRLF throughout.
 
+import { T5_ZOMBIE_MAPS } from './map-aliases.js';
+
 interface CfgLine {
     kind: 'set' | 'raw';
     key?: string;
@@ -122,3 +124,38 @@ export function composeCfg(baselineText: string, overlays: OverlayInput[]): stri
     // matches upstream cfg conventions.
     return bodyLines.join(parsed.eol) + parsed.eol;
 }
+
+/** Compose a server config, with its catalog map taking precedence over presets. */
+export function composeServerCfg(
+    baselineText: string,
+    overlays: OverlayInput[],
+    game: string | null,
+    map: string | null
+): string {
+    const composed = composeCfg(baselineText, overlays);
+    const selected = game === 't5' ? T5_ZOMBIE_MAPS.find((entry) => entry.canonical === map) : undefined;
+    // Legacy/unrecognized servers retain their existing config semantics.
+    if (!selected) return composed;
+
+    const eol = parseCfg(composed).eol;
+    const lines = composed.split(/\r?\n/);
+    lines.pop(); // composeCfg always emits a trailing newline.
+    const rotation = `set sv_maprotation "map ${selected.canonical}"`;
+    // Dvars are case-insensitive. Remove duplicate assignments, including
+    // seta and bare forms, so old map-choice overlays cannot undo selection.
+    const isRotation = /^\s*(?:(?:set|seta)\s+)?sv_maprotation\s+/i;
+    let applied = false;
+    const result: string[] = [];
+    for (const line of lines) {
+        if (!isRotation.test(line)) {
+            result.push(line);
+        } else if (!applied) {
+            result.push(rotation);
+            applied = true;
+        }
+    }
+    if (!applied) {
+        result.push('// Map selected by Electric Cherry', rotation);
+    }
+    return result.join(eol) + eol;
+}