Address PR review comments

- Treat None as "unset" in air_project_path setter (reverts to
  env var / default instead of crashing with Path(None))
- Use __dict__.copy() in config_context() so new fields are
  automatically saved/restored
- Mention both config property and env var in error messages
  for output_format and transform_tiling_script
- Incorporate PR #44 logging changes (rebase on top of
  feature/logging-knob-issue-40)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erwei-xilinx

amd_triton_npu/backend/config.py

@@ -148,6 +148,9 @@ def air_project_path(self) -> Path:
 
     @air_project_path.setter
     def air_project_path(self, value):
+        if value is None:
+            self._air_project_path = _UNSET
+            return
         self._air_project_path = value
 
     # ---- utilities ----
@@ -198,16 +201,10 @@ def config_context(**kwargs):
         with config_context(compile_only=True):
             kernel[grid](a, b, c)
     """
-    saved = {
-        "_compile_only": npu_config._compile_only,
-        "_transform_tiling_script": npu_config._transform_tiling_script,
-        "_bf16_emulation": npu_config._bf16_emulation,
-        "_output_format": npu_config._output_format,
-        "_air_project_path": npu_config._air_project_path,
-    }
+    saved = npu_config.__dict__.copy()
     try:
         set_config(**kwargs)
         yield npu_config
     finally:
-        for attr, val in saved.items():
-            object.__setattr__(npu_config, attr, val)
+        npu_config.__dict__.clear()
+        npu_config.__dict__.update(saved)

amd_triton_npu/backend/driver.py

@@ -220,7 +220,8 @@ def _get_output_format():
         if configured_format == "elf" and npu_version == "npu1":
             raise RuntimeError(
                 "ELF output format is not supported on npu1 (AIE2) devices. "
-                "Use 'xclbin' or set npu_config.output_format = None."
+                "Unset or change AMD_TRITON_NPU_OUTPUT_FORMAT, or set "
+                "npu_config.output_format to 'xclbin' or None."
             )
         return configured_format
     # Auto-detect: ELF for npu2, xclbin for npu1
@@ -427,9 +428,10 @@ def _get_transform_ir_string():
     if custom_script_path:
         if not os.path.isfile(custom_script_path):
             raise FileNotFoundError(
-                f"transform_tiling_script is set to '{custom_script_path}' "
-                f"but the file was not found (cwd: {os.getcwd()}). "
-                f"Use an absolute path or run from the directory containing the script."
+                f"transform_tiling_script / AIR_TRANSFORM_TILING_SCRIPT is set to "
+                f"'{custom_script_path}' but the file was not found "
+                f"(cwd: {os.getcwd()}). Use an absolute path or run from the "
+                f"directory containing the script."
             )
         with open(custom_script_path, "r") as f:
             logger.debug("Using custom tiling script from: %s", custom_script_path)