fix: resolve 8 bugs affecting real users

- Fix KeyError 'root' in FileGrouper when merging groups with no root-level files
- Fix changelog commit parsing breaking on multiline bodies (use %x00 separator)
- Add empty choices/content checks in OpenAI, Anthropic, OpenRouter providers
- Fix config edit crash when config is empty
- Fix validate command using wrong color for 'no staged files'
- Add type check for corrupted YAML config (non-dict returns empty dict)

devgen/modules/changelog_generator.py

@@ -32,17 +32,21 @@ class ChangelogGenerator:
         else:
             cmd = self._resolve_range(to_ref)
         try:
-            return run_git_command(cmd).split("\n")
+            output = run_git_command(cmd)
+            # Use %x00 as separator to avoid splitting on newlines in commit bodies
+            # Then filter out empty strings
+            return [c for c in output.split("\0") if c.strip()]
         except subprocess.CalledProcessError as e:
             self.logger.error(f"Git command failed: {e}")
             raise RuntimeError(f"Git command failed: {e}") from e
 
     def _log_cmd(self, range_spec: str) -> List[str]:
-        # Format: hash|author|date|subject|body
+        # Format: hash|author|date|subject|body (separated by %x00 to avoid
+        # splitting on newlines within commit bodies)
         return [
             "git",
             "log",
-            "--format=%H|%an|%ad|%s|%b",
+            "--format=%H|%an|%ad|%s|%b%x00",
             "--date=short",
             range_spec,
         ]

devgen/modules/diff_builder.py

@@ -129,10 +129,7 @@ class FileGrouper:
             parent_path = str(Path(deepest).parent)
             new_key = "root" if parent_path == "." else parent_path
             files = groups.pop(deepest)
-            if new_key in groups:
-                groups[new_key].extend(files)
-            else:
-                groups["root"].extend(files)
+            groups.setdefault(new_key, []).extend(files)
         return groups