Disable sampler on error (#426)

mentat/sampler/sampler.py

@@ -45,6 +45,7 @@ def parse_message(message: ChatCompletionMessageParam) -> dict[str, str]:
 
 
 class Sampler:
+    active: bool = True
     diff_active: str | None = None
     commit_active: str | None = None
     last_sample_id: str | None = None

mentat/sampler/utils.py

@@ -12,6 +12,11 @@ def get_active_snapshot_commit(repo: Repo) -> str | None:
     """Returns the commit hash of the current active snapshot, or None if there are no active changes."""
     if not repo.is_dirty():
         return None
+    if not repo.config_reader().has_option("user", "name"):
+        raise SampleError(
+            "ERROR: Git user.name not set. Please run 'git config --global user.name"
+            ' "Your Name"\'.'
+        )
     try:
         # Stash active changes and record the current position
         for file in get_non_gitignored_files(Path(repo.working_dir)):

mentat/session.py

@@ -20,7 +20,13 @@
 from mentat.conversation import Conversation
 from mentat.cost_tracker import CostTracker
 from mentat.ctags import ensure_ctags_installed
-from mentat.errors import ContextSizeInsufficient, MentatError, SessionExit, UserError
+from mentat.errors import (
+    ContextSizeInsufficient,
+    MentatError,
+    SampleError,
+    SessionExit,
+    UserError,
+)
 from mentat.git_handler import get_git_root_for_path
 from mentat.llm_api_handler import LlmApiHandler, is_test_environment
 from mentat.logging_config import setup_logging
@@ -179,8 +185,16 @@ async def _main(self):
                     for file_edit in file_edits:
                         file_edit.resolve_conflicts()
 
-                    if session_context.sampler:
-                        session_context.sampler.set_active_diff()
+                    if session_context.sampler and session_context.sampler.active:
+                        try:
+                            session_context.sampler.set_active_diff()
+                        except SampleError as e:
+                            stream.send(
+                                f"Sampler error setting active diff: {e}. Disabling"
+                                " sampler.",
+                                color="red",
+                            )
+                            session_context.sampler.active = False
 
                     applied_edits = await code_file_manager.write_changes_to_files(
                         file_edits