fix: handle truncated tool call JSON — guide model to use bash heredoc for large files

When file_write gets a 15KB+ HTML payload, the streaming JSON gets
truncated. Now catches JSON parse errors and returns a specific
hint to use bash heredoc instead of silently failing.

src/bot/index.js

@@ -426,7 +426,20 @@ export async function initBot(config, api, tools, skills, agents) {
           if (!handler) {
             result = `❌ Unknown tool: ${fn.name}`;
           } else {
-            const args = JSON.parse(fn.arguments || '{}');
+            let args;
+            try {
+              args = JSON.parse(fn.arguments || '{}');
+            } catch (parseErr) {
+              // Tool call JSON was truncated (common with large file content in file_write)
+              const argLen = (fn.arguments || '').length;
+              result = `❌ ${fn.name} failed: Tool call arguments JSON was truncated (${argLen} chars). ` +
+                (fn.name === 'file_write'
+                  ? 'The file content is too large for a single tool call. Use bash with heredoc instead: bash({ command: "cat > /path/to/file << \'EOF\'\\ncontent here\\nEOF" })'
+                  : 'Retry with shorter arguments or split into smaller calls.');
+              logger.error(`  → ${fn.name} failed: ${parseErr.message} (args length: ${argLen})`);
+              loopMessages.push({ role: 'tool', tool_call_id: tc.id, content: result });
+              continue;
+            }
             logger.info(`  → ${fn.name}(${fn.arguments?.slice(0, 100)})`);
             result = String(await handler(args)).slice(0, 8000);
           }