fix: salvage backstory from truncated JSON, request compact output

Model sometimes returns pretty-printed JSON with newlines/indentation,
wasting tokens and causing truncation. Now requests compact single-line
JSON. When JSON is truncated, regex-extracts the backstory field rather
than setting raw JSON as the backstory text.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/llm/backstoryGenerator.ts

@@ -120,7 +120,15 @@ export async function generateBackstoryAndDesires(
   try {
     parsed = JSON.parse(result);
   } catch {
-    // JSON parse failed — use raw string as backstory fallback
+    // Try to salvage truncated JSON — extract backstory field even if desires are cut off
+    const backstoryMatch = result.match(/"backstory"\s*:\s*"((?:[^"\\]|\\.)*)"/);
+    if (backstoryMatch) {
+      logService?.log('warning', 'LLM', `JSON truncated for backstory (entity ${entityId}), salvaged backstory field`);
+      logLlmDebug({ templateName: 'backstoryAndDesires', stage: 'parse_salvaged', response: result });
+      world.addComponent<string>(entityId, 'backstory', backstoryMatch[1]);
+      return;
+    }
+    // Truly unparseable — use raw string as backstory fallback
     logService?.log('warning', 'LLM', `JSON parse failed for backstory (entity ${entityId}), using raw string`);
     logLlmDebug({ templateName: 'backstoryAndDesires', stage: 'parse_failed', response: result });
     world.addComponent<string>(entityId, 'backstory', result);

server/src/llm/templates.ts

@@ -75,7 +75,7 @@ export const templates: Record<string, PromptTemplate> = {
       'The backstory should reflect their personality without referencing professions or institutions that do not exist. ' +
       'Desires should be grounded in what is achievable or aspirational given the current world state.\n\n' +
       'Be concise. Keep backstory under 2 sentences. Keep desire descriptions short (under 10 words).\n\n' +
-      'Respond ONLY with a valid JSON object. No explanation, no markdown, just JSON.',
+      'Respond ONLY with compact single-line JSON. No newlines, no indentation, no markdown.',
     userPrompt:
       'New settler: {{npcName}}\n' +
       'Stats (each ranges 3-18, 10 is average): {{stats}}\n\n' +