feat(BA-6600): return per-requirement selection failures with suggestions

changes/12448.enhance.md

@@ -0,0 +1 @@
+Evaluate every kernel requirement during agent selection and report each placement failure with a structured remediation suggestion, instead of aborting at the first unplaceable kernel.

src/ai/backend/manager/sokovan/scheduler/provisioner/selectors/__init__.py

@@ -8,19 +8,19 @@
     NoAvailableAgentError,
     NoCompatibleAgentError,
 )
-
-# Then import selector which depends on exceptions
 from .selector import (
     AbstractAgentSelector,
     AgentSelection,
     AgentSelectionConfig,
     AgentSelectionCriteria,
     AgentSelector,
     KernelResourceSpec,
-    ResourceRequirements,
     SessionMetadata,
 )
 
+# Then import selector which depends on exceptions
+from .types import ResourceRequirements
+
 __all__ = [
     # Exceptions
     "AgentSelectionError",

src/ai/backend/manager/sokovan/scheduler/provisioner/selectors/concentrated.py

@@ -18,8 +18,8 @@
     AgentSelectionConfig,
     AgentSelectionCriteria,
     AgentStateTracker,
-    ResourceRequirements,
 )
+from .types import ResourceRequirements
 from .utils import count_unutilized_capabilities, order_slots_by_priority
 
 

src/ai/backend/manager/sokovan/scheduler/provisioner/selectors/dispersed.py

@@ -14,8 +14,8 @@
     AgentSelectionConfig,
     AgentSelectionCriteria,
     AgentStateTracker,
-    ResourceRequirements,
 )
+from .types import ResourceRequirements
 from .utils import count_unutilized_capabilities, order_slots_by_priority