Add Go worker agent prototype

coordinator/internal/agent/sanitize.go

@@ -0,0 +1,58 @@
+package agent
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+)
+
+var (
+	// Go's regexp (RE2) has no lookbehind, so these patterns conservatively
+	// anchor on the characters that typically precede a local path:
+	// whitespace, quotes, parens, brackets, or the start of the message.
+	windowsPathPattern = regexp.MustCompile(`[A-Za-z]:\\[^\s'"\],)]+`)
+	posixPathPattern   = regexp.MustCompile(`(^|[\s'"(\[=])/(?:[^\s'"\],)]+)`)
+)
+
+// SanitizeErrorMessage keeps coordinator-visible failures useful without
+// exposing local paths. It mirrors the Python worker's sanitizer: local work
+// directories and absolute paths are redacted, and the message is truncated
+// to 300 characters.
+func SanitizeErrorMessage(message string, workDir string) string {
+	message = strings.ReplaceAll(message, workDir, "<worker-dir>")
+	message = windowsPathPattern.ReplaceAllString(message, "<path>")
+	message = posixPathPattern.ReplaceAllString(message, "${1}<path>")
+	if len(message) > 300 {
+		message = message[:300]
+	}
+	return message
+}
+
+// IsRetryableError classifies failures for the coordinator. Invalid scientific
+// input and missing local tools are permanent; everything else (transient
+// transport errors, unexpected runner failures) may be retried.
+func IsRetryableError(err error) bool {
+	if err == nil {
+		return false
+	}
+	switch err.(type) {
+	case *CoordinatorError:
+		return false
+	case *os.PathError:
+		return false
+	}
+	return true
+}
+
+// TaskRunnerExit classifies subprocess exits.
+const (
+	ExitPermanent = 3 // runner classified the failure as invalid input
+)
+
+func runnerExitError(exit int, stderr string) error {
+	if exit == ExitPermanent {
+		return &CoordinatorError{msg: stderr}
+	}
+	return fmt.Errorf("task runner failed with exit code %d: %s", exit, stderr)
+}