diff --git a/docs/reference/cli.md b/docs/reference/cli.md
index f3a6d129..120b0017 100644
--- a/docs/reference/cli.md
+++ b/docs/reference/cli.md
@@ -275,6 +275,7 @@ bench eval run --tasks-dir ./tasks --matrix matrix.yaml --trials 3
 | `--canonical-jobs-dir` | — | Materialize selected rollout directories for trainer conversion |
 | `--retry-policy` | `default` | Retry policy label for reproducible eval artifacts: `default` or `unscored-only` |
 | `--retry-attempts` | — | Override retry attempts for the eval run |
+| `--max-retries` | — | Alias for `--retry-attempts`; maximum retries per task |
 | `--retry-concurrency` | — | Reserved retry concurrency setting recorded in run config |
 | `--publish-hf` | — | Upload final eval artifacts to this Hugging Face dataset repo |
 | `--hf-prefix` | — | Path prefix inside the Hugging Face repo; requires `--publish-hf` |
diff --git a/src/benchflow/_utils/scoring.py b/src/benchflow/_utils/scoring.py
index b29efee3..9333bfd5 100644
--- a/src/benchflow/_utils/scoring.py
+++ b/src/benchflow/_utils/scoring.py
@@ -117,6 +117,10 @@ def classify_error(error: str | None) -> str | None:
     if not error:
         return None
     lower = error.lower()
+    if "missing credential" in lower or (
+        "required for model" in lower and "not set" in lower
+    ):
+        return PROVIDER_AUTH
     if "agent idle for" in lower:
         return IDLE_TIMEOUT
     if "install failed" in lower:
diff --git a/src/benchflow/agents/env.py b/src/benchflow/agents/env.py
index ebf83e15..e2fd1fda 100644
--- a/src/benchflow/agents/env.py
+++ b/src/benchflow/agents/env.py
@@ -72,6 +72,10 @@
 _AZURE_HOST_SUFFIXES = (".openai.azure.com", ".services.ai.azure.com")
 
 
+class MissingAgentCredentialError(ValueError):
+    """Raised when an agent/model pair is missing a required credential."""
+
+
 def _derive_azure_resource(agent_env: dict[str, str]) -> None:
     """Populate AZURE_RESOURCE from AZURE_API_ENDPOINT when not already set."""
     if agent_env.get(_AZURE_RESOURCE_ENV):
@@ -794,7 +798,7 @@ def resolve_agent_env(
                     required_key,
                 )
             else:
-                raise ValueError(
+                raise MissingAgentCredentialError(
                     f"{required_key} required for model {model!r} but not set. "
                     "Pass it explicitly (for example via --agent-env/agent_env) "
                     "or define it in .env."
diff --git a/src/benchflow/cli/main.py b/src/benchflow/cli/main.py
index 092e1617..8870ff05 100644
--- a/src/benchflow/cli/main.py
+++ b/src/benchflow/cli/main.py
@@ -557,6 +557,13 @@ def eval_run(
         int | None,
         typer.Option("--retry-attempts", help="Reserved retry-attempt override"),
     ] = None,
+    max_retries: Annotated[
+        int | None,
+        typer.Option(
+            "--max-retries",
+            help="Alias for --retry-attempts; maximum retries per task.",
+        ),
+    ] = None,
     retry_concurrency: Annotated[
         int | None,
         typer.Option("--retry-concurrency", help="Reserved retry concurrency"),
@@ -592,6 +599,13 @@ def eval_run(
     """
     _apply_dotenv_to_process_env()
 
+    if retry_attempts is not None and max_retries is not None:
+        print_error("--retry-attempts and --max-retries are aliases; pass only one")
+        raise typer.Exit(1)
+    retry_attempt_override = (
+        retry_attempts if retry_attempts is not None else max_retries
+    )
+
     request = EvalCreateRequest(
         config_file=config_file,
         tasks_dir=tasks_dir,
@@ -636,7 +650,7 @@ def eval_run(
         canonical_selection_out=canonical_selection_out,
         canonical_jobs_dir=canonical_jobs_dir,
         retry_policy=retry_policy,
-        retry_attempts=retry_attempts,
+        retry_attempts=retry_attempt_override,
         retry_concurrency=retry_concurrency,
         publish_hf=publish_hf,
         hf_prefix=hf_prefix,
@@ -901,6 +915,8 @@ def _run_config_file_eval(plan: "EvalPlan") -> None:
             j._config.prompts = plan.eval_prompts
         if req.agent_idle_timeout is not None:
             j._config.agent_idle_timeout = plan.eval_agent_idle_timeout
+        if req.retry_attempts is not None:
+            j._config.retry.max_retries = req.retry_attempts
         if plan.usage_tracking_overridden:
             j._config.usage_tracking = j._config.usage_tracking.overlay(
                 plan.eval_usage_tracking
diff --git a/src/benchflow/evaluation.py b/src/benchflow/evaluation.py
index 37fc5e1c..ceda266c 100644
--- a/src/benchflow/evaluation.py
+++ b/src/benchflow/evaluation.py
@@ -789,10 +789,12 @@ def from_yaml(cls, path: str | Path, **kwargs) -> Evaluation:
         # Detect format: legacy uses "agents" + "datasets", benchflow uses "agent"
         if "agents" in raw or "datasets" in raw:
             return cls._from_legacy_yaml(raw, **kwargs)
-        return cls._from_native_yaml(raw, **kwargs)
+        return cls._from_native_yaml(raw, config_path=path, **kwargs)
 
     @classmethod
-    def _from_native_yaml(cls, raw: dict, **kwargs) -> Evaluation:
+    def _from_native_yaml(
+        cls, raw: dict, config_path: Path | None = None, **kwargs
+    ) -> Evaluation:
         """Parse benchflow-native YAML."""
         from benchflow._utils.benchmark_repos import (
             TASK_ALIASES,
@@ -826,9 +828,23 @@ def _from_native_yaml(cls, raw: dict, **kwargs) -> Evaluation:
         elif "tasks_dir" in raw:
             # Legacy single-string format (backward compat).
             ref = raw["tasks_dir"]
+            if not isinstance(ref, str | Path):
+                raise ValueError(
+                    f"YAML 'tasks_dir' must be a path string; got {type(ref).__name__}."
+                )
             tasks_dir = Path(ref)
             if not tasks_dir.exists() and ref in TASK_ALIASES:
                 tasks_dir = ensure_tasks(ref)
+            elif not tasks_dir.exists() and str(ref) == ".cache/programbench-benchflow":
+                config_note = f" in {config_path}" if config_path is not None else ""
+                raise ValueError(
+                    f"YAML tasks_dir not found{config_note}: {ref}. "
+                    "Generate ProgramBench tasks first with "
+                    "`python benchmarks/programbench/run_programbench.py "
+                    "benchmarks/programbench/programbench-gemini-flash-lite.yaml` "
+                    "or `python -m benchmarks.programbench.main --output-dir "
+                    ".cache/programbench-benchflow`."
+                )
         else:
             raise ValueError("YAML config must have 'source' or 'tasks_dir'")
 
diff --git a/src/benchflow/rollout/__init__.py b/src/benchflow/rollout/__init__.py
index 2567fc00..db89e259 100644
--- a/src/benchflow/rollout/__init__.py
+++ b/src/benchflow/rollout/__init__.py
@@ -75,6 +75,7 @@
 from benchflow._utils.scoring import classify_error as classify_error
 from benchflow.acp.types import McpServerSpec
 from benchflow.agents.credentials import upload_credential
+from benchflow.agents.env import MissingAgentCredentialError
 from benchflow.agents.registry import AGENTS
 from benchflow.contracts import (
     AgentProtocolError,
@@ -2039,6 +2040,9 @@ async def run(self) -> RolloutResult:
             # placeholder during cleanup.
             self._error = str(e)
             logger.error(str(e))
+        except MissingAgentCredentialError as e:
+            self._error = f"Missing credential: {e}"
+            logger.error(self._error)
         except Exception as e:
             self._error = str(e)
             logger.error("Run failed", exc_info=True)
diff --git a/tests/test_agent_idle_timeout_cli.py b/tests/test_agent_idle_timeout_cli.py
index a38891a7..0d03f1a0 100644
--- a/tests/test_agent_idle_timeout_cli.py
+++ b/tests/test_agent_idle_timeout_cli.py
@@ -74,6 +74,57 @@ def test_eval_create_reasoning_effort_lands_in_config(tmp_path: Path):
     assert captured["config"].reasoning_effort == "max"
 
 
+def test_eval_create_max_retries_alias_lands_in_config(tmp_path: Path):
+    """Guards the fix from PR #918 / Linear ENG-169: --max-retries reaches RetryConfig."""
+    tasks = _make_tasks_dir(tmp_path)
+    captured: dict = {}
+
+    with _stub_evaluation_run(captured):
+        eval_run(
+            tasks_dir=tasks,
+            max_retries=3,
+            jobs_dir=str(tmp_path / "jobs"),
+        )
+
+    assert captured["config"].retry.max_retries == 3
+
+
+def test_eval_create_max_retries_alias_overrides_yaml_config(tmp_path: Path):
+    """Guards the fix from PR #918 / Linear ENG-169 on --config eval runs."""
+    tasks = _make_tasks_dir(tmp_path)
+    yaml_path = tmp_path / "config.yaml"
+    yaml_path.write_text(
+        "tasks_dir: " + str(tasks) + "\nagent: oracle\nmax_retries: 1\n"
+    )
+    captured: dict = {}
+
+    with _stub_evaluation_run(captured):
+        eval_run(
+            config_file=yaml_path,
+            max_retries=4,
+            jobs_dir=str(tmp_path / "jobs"),
+        )
+
+    assert captured["config"].retry.max_retries == 4
+
+
+def test_eval_create_rejects_duplicate_retry_aliases(tmp_path: Path):
+    """Guards the fix from PR #918 / Linear ENG-169 against ambiguous retry aliases."""
+    tasks = _make_tasks_dir(tmp_path)
+
+    try:
+        eval_run(
+            tasks_dir=tasks,
+            retry_attempts=1,
+            max_retries=2,
+            jobs_dir=str(tmp_path / "jobs"),
+        )
+    except typer.Exit as exc:
+        assert exc.exit_code == 1
+    else:
+        raise AssertionError("expected typer.Exit for duplicate retry aliases")
+
+
 def test_eval_create_reasoning_effort_overrides_yaml_config(tmp_path: Path):
     """Guards SkillsBench PR #825 so CLI effort overrides YAML defaults."""
     tasks = _make_tasks_dir(tmp_path)
diff --git a/tests/test_cli_edge_case_hardening.py b/tests/test_cli_edge_case_hardening.py
index 3bb97a04..e9863c06 100644
--- a/tests/test_cli_edge_case_hardening.py
+++ b/tests/test_cli_edge_case_hardening.py
@@ -9,6 +9,7 @@
 
 import json
 import os
+from pathlib import Path
 from types import SimpleNamespace
 
 import pytest
@@ -230,6 +231,46 @@ def test_yaml_string_prompts_are_wrapped_in_a_list(tmp_path):
     assert ev._config.prompts == ["do the thing"]
 
 
+def test_from_yaml_rejects_missing_tasks_dir_with_programbench_hint(tmp_path):
+    """Guards the fix from PR #918 / Linear ENG-162: missing ProgramBench tasks fail cleanly."""
+    from benchflow.evaluation import Evaluation
+
+    p = tmp_path / "programbench.yaml"
+    p.write_text("tasks_dir: .cache/programbench-benchflow\nagent: oracle\n")
+
+    with pytest.raises(ValueError, match=r"run_programbench\.py"):
+        Evaluation.from_yaml(p)
+
+
+def test_from_yaml_accepts_existing_programbench_tasks_dir(tmp_path, monkeypatch):
+    """Guards the fix from PR #918 / Linear ENG-162: generated ProgramBench dirs load."""
+    from benchflow.evaluation import Evaluation
+
+    (tmp_path / ".cache" / "programbench-benchflow").mkdir(parents=True)
+    p = tmp_path / "programbench.yaml"
+    p.write_text("tasks_dir: .cache/programbench-benchflow\nagent: oracle\n")
+
+    monkeypatch.chdir(tmp_path)
+
+    ev = Evaluation.from_yaml(p)
+
+    assert ev._tasks_dir == Path(".cache/programbench-benchflow")
+
+
+def test_eval_create_config_missing_tasks_dir_no_raw_traceback(tmp_path):
+    """Guards the fix from PR #918 / Linear ENG-162 at the CLI config boundary."""
+    p = tmp_path / "programbench.yaml"
+    p.write_text("tasks_dir: .cache/programbench-benchflow\nagent: oracle\n")
+
+    res = runner.invoke(app, ["eval", "create", "--config", str(p)])
+
+    assert res.exit_code == 1
+    assert "Traceback (most recent call last)" not in res.output
+    normalized = " ".join(res.output.split())
+    assert "YAML tasks_dir not found" in normalized
+    assert "run_programbench.py" in res.output
+
+
 # ── markup in user input crashes error handlers (H10/M13) ─────────────────────
 
 
diff --git a/tests/test_provider_auth_detection.py b/tests/test_provider_auth_detection.py
index 1f745f09..3de9c014 100644
--- a/tests/test_provider_auth_detection.py
+++ b/tests/test_provider_auth_detection.py
@@ -395,6 +395,30 @@ def spy_classify(e):
     assert rollout._provider_auth_status_cached == 401
 
 
+@pytest.mark.asyncio
+async def test_run_missing_credential_error_is_clean_provider_auth(
+    tmp_path, monkeypatch, caplog
+):
+    """Guards the fix from PR #918 / Linear ENG-257: missing credentials avoid tracebacks."""
+    from benchflow._utils.scoring import PROVIDER_AUTH, classify_error
+    from benchflow.agents.env import MissingAgentCredentialError
+
+    rollout = _auth_rollout(tmp_path, usage_source="unavailable")
+    rollout._rollout_dir = None
+    missing = MissingAgentCredentialError(
+        "GEMINI_API_KEY required for model 'gemini/gemini-3.1-flash' but not set."
+    )
+
+    monkeypatch.setattr(rollout, "setup", AsyncMock(side_effect=missing))
+    caplog.set_level("ERROR", logger="benchflow.rollout")
+
+    result = await rollout.run()
+
+    assert result.error == f"Missing credential: {missing}"
+    assert classify_error(result.error) == PROVIDER_AUTH
+    assert "Run failed" not in caplog.text
+
+
 def test_enforcement_still_fires_when_no_error_and_usage_missing(tmp_path):
     """Negative control for FIX 1 (PR #564 / issue #546): on a clean run with no
     ACP error and no captured provider usage, the legitimate required-usage