feat(dataset-builder): add retry logic and ASCII-safe logging for Siemens PDF pipeline

- question_generator.py: add max_retries=3/retry_delay=5s loop with
  exponential backoff on LLM timeout or server errors; encode filenames
  with ascii/replace before printing to avoid UnicodeEncodeError on
  Windows cp1252 consoles
- runner.py: encode PDF filenames ASCII-safe for progress messages;
  catch generation failures per-document and skip (or re-raise) based
  on failure_mode, preventing one bad doc from aborting the whole build

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

rag_eval/dataset_builder/generator/question_generator.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+import time
 from abc import ABC, abstractmethod
 from typing import Any
 
@@ -150,13 +151,18 @@ class OpenAIQuestionGenerator(QuestionGenerator):
         max_questions: int,
         max_chunks_per_question: int,
         job_name: str,
+        max_retries: int = 3,
+        retry_delay: float = 5.0,
     ) -> list[DraftQuestionSample]:
-        """Generate draft questions for one parsed document."""
+        """Generate draft questions for one parsed document, with retry on timeout/server errors."""
         prompt = self._build_prompt(
             document,
             max_questions=max_questions,
             max_chunks_per_question=max_chunks_per_question,
         )
+        last_exc: Exception | None = None
+        for attempt in range(1, max_retries + 1):
+            try:
                 response = self.client.chat.completions.create(
                     model=self.model,
                     messages=[
@@ -171,3 +177,13 @@ class OpenAIQuestionGenerator(QuestionGenerator):
                     self._build_sample(document=document, payload=item, index=index, job_name=job_name)
                     for index, item in enumerate(payload[:max_questions], start=1)
                 ]
+            except Exception as exc:
+                last_exc = exc
+                if attempt < max_retries:
+                    wait = retry_delay * attempt
+                    doc_name_safe = document.doc_name.encode("ascii", "replace").decode("ascii")
+                    print(f"  [warn] generate attempt {attempt}/{max_retries} failed for {doc_name_safe!r}: {exc}. Retrying in {wait:.0f}s...")
+                    time.sleep(wait)
+        raise RuntimeError(
+            f"Question generation failed for {document.doc_name!r} after {max_retries} attempts"
+        ) from last_exc

rag_eval/dataset_builder/runner.py

@@ -111,12 +111,32 @@ def run_dataset_build(
             continue
 
         documents.append(document)
+        doc_name_safe = pdf_path.name.encode("ascii", "replace").decode("ascii")
+        print(f"  [info] generating questions for: {doc_name_safe}")
+        try:
             generated = generator.generate(
                 document,
                 max_questions=job.max_questions_per_document,
                 max_chunks_per_question=job.max_source_chunks_per_question,
                 job_name=job.job_name,
             )
+        except Exception as exc:
+            gen_failure = ParseFailure(file_path=pdf_path.as_posix(), error=f"generation failed: {exc}")
+            failures.append(gen_failure)
+            print(f"  [warn] skipping {doc_name_safe} after generation failure: {exc}")
+            if job.failure_mode == "fail":
+                result = DatasetBuildResult(
+                    job=job,
+                    run_id=run_id,
+                    artifact_paths=artifact_paths,
+                    documents=documents,
+                    draft_samples=draft_samples,
+                    parse_failures=failures,
+                )
+                write_dataset_build_artifacts(result)
+                raise
+            continue
+
         valid_generated = []
         for sample in generated:
             errors = validate_draft_sample(
@@ -126,9 +146,9 @@ def run_dataset_build(
             )
             if not errors:
                 valid_generated.append(sample)
-        draft_samples.extend(
-            dedupe_samples(valid_generated)[: job.max_questions_per_document]
-        )
+        new_samples = dedupe_samples(valid_generated)[: job.max_questions_per_document]
+        draft_samples.extend(new_samples)
+        print(f"  [info] {doc_name_safe}: {len(new_samples)} questions generated (total so far: {len(draft_samples)})")
 
     result = DatasetBuildResult(
         job=job,