fix(tstest): preserve streaming console output and correctly buffer incomplete TAP lines

ts/tstest.logging.ts

@@ -348,10 +348,10 @@ export class TsTestLogger {
     }
   }
   
-  // Console output from test files (non-TAP output)
+  // Console output from test files (non-TAP output) - complete lines
   testConsoleOutput(message: string) {
     if (this.options.json) return;
-    
+
     // In verbose mode, show console output immediately
     if (this.options.verbose) {
       this.log(this.format(`   ${message}`, 'dim'));
@@ -359,12 +359,48 @@ export class TsTestLogger {
       // In non-verbose mode, buffer the logs
       this.currentTestLogs.push(message);
     }
-    
+
     // Always log to test file if --logfile is specified
     if (this.currentTestLogFile) {
       this.logToTestFile(`   ${message}`);
     }
   }
+
+  // Streaming console output (preserves original formatting, no newline added)
+  testConsoleOutputStreaming(message: string) {
+    if (this.options.json) return;
+
+    const prefix = '   ';
+    if (this.options.verbose) {
+      // Use process.stdout.write to preserve streaming without adding newlines
+      process.stdout.write(this.format(prefix + message, 'dim'));
+    } else {
+      // Buffer without trailing newline - append to last entry if exists and incomplete
+      if (this.currentTestLogs.length > 0) {
+        // Append to the last buffered entry (for streaming segments)
+        this.currentTestLogs[this.currentTestLogs.length - 1] += message;
+      } else {
+        this.currentTestLogs.push(message);
+      }
+    }
+
+    // Log to test file without adding newline
+    if (this.currentTestLogFile) {
+      this.logToTestFileRaw(prefix + message);
+    }
+  }
+
+  private logToTestFileRaw(message: string) {
+    try {
+      // Remove ANSI color codes for file logging
+      const cleanMessage = message.replace(/\u001b\[[0-9;]*m/g, '');
+
+      // Append to test log file without adding newline
+      fs.appendFileSync(this.currentTestLogFile, cleanMessage);
+    } catch (error) {
+      // Silently fail to avoid disrupting the test run
+    }
+  }
   
   // Skipped test file
   testFileSkipped(filename: string, index: number, total: number, reason: string) {