separate the concerns, leave hardcoded groups for testing

Author: asirko-soft

scripts/build/build/target.py

@@ -225,14 +225,30 @@ def __init__(self, name, builder_class, **kwargs):
     def isUnifiedBuild(self, parts: List[TargetPart]):
         """Checks if the given parts combine into a unified build.
 
-        Returns the unified group ID (e.g., 'main', 'no-read-client', 'rpc-json')
-        if this is a unified build, or None otherwise.
+        Returns the unified group ID based on the combination of modifiers present.
+        The group determines which output directory and build configuration to use.
         """
+        has_unified = False
         for part in parts:
             if part.build_arguments.get('unified', False):
-                # Return the group ID, defaulting to 'main' for backward compatibility
-                return part.build_arguments.get('unified_group', 'main')
-        return None
+                has_unified = True
+                break
+
+        if not has_unified:
+            return None
+
+        # Auto-detect unified group based on which other modifiers are present
+        has_no_read_client = any(part.build_arguments.get('chip_enable_read_client', None) == False
+                                 for part in parts)
+        has_rpc = any(part.build_arguments.get('enable_rpcs', False)
+                      for part in parts)
+
+        if has_no_read_client:
+            return 'group2'
+        elif has_rpc:
+            return 'group3'
+        else:
+            return 'main'
 
     def AppendFixedTargets(self, parts: List[TargetPart]):
         """Append a list of potential targets/variants.
@@ -467,12 +483,17 @@ def Create(self, name: str, runner, repository_path: str, output_prefix: str,
         for part in parts:
             kargs.update(part.build_arguments)
 
+        # Determine unified group before creating builder
+        unified_group = self.isUnifiedBuild(parts)
+        if unified_group:
+            kargs['unified_group'] = unified_group
+
         logging.info("Preparing builder '%s'" % (name,))
 
         builder = self.builder_class(repository_path, runner=runner, **kargs)
         builder.target = self
         builder.identifier = name
-        unified_group = self.isUnifiedBuild(parts)
+
         if unified_group:
             # Use group-specific output directory
             # group2 = apps with chip_enable_read_client=false

scripts/build/builders/host.py

@@ -416,16 +416,18 @@ def __init__(self, root, runner, app: HostApp, board=HostBoard.NATIVE,
                  enable_webrtc=False,
                  terms_and_conditions_required: Optional[bool] = None, chip_enable_nfc_based_commissioning=None,
                  chip_enable_read_client=True,
-                 unified=False
+                 unified=False,
+                 unified_group=None
                  ):
         """
         Construct a host builder.
 
         Params (limited docs, documenting interesting ones):
 
            - unified: build will happen in a SINGLE output directory instead of separated out
-                      into per-target directories. The specific unified group is automatically
-                      determined based on build configuration (chip_enable_read_client, enable_rpcs, etc.)
+                      into per-target directories.
+           - unified_group: which unified group this build belongs to (determined automatically
+                           by target.py based on modifiers present)
         """
 
         # Unified builds use the top level root for compilation
@@ -455,21 +457,14 @@ def __init__(self, root, runner, app: HostApp, board=HostBoard.NATIVE,
             self.extra_gn_options.append('chip_enable_read_client=false')
 
         if unified:
-            # Auto-detect unified group based on build configuration
-            if not chip_enable_read_client:
-                unified_group = 'group2'
-            elif enable_rpcs:
-                unified_group = 'group3'
-            else:
-                unified_group = 'main'
-            
             self.extra_gn_options.append('target_os="all"')
             self.extra_gn_options.append('matter_enable_tracing_support=true')
             # All unified builds use JSON logging for better debugging
             self.extra_gn_options.append('matter_log_json_payload_hex=true')
             self.extra_gn_options.append('matter_log_json_payload_decode_full=true')
 
-            self.build_command = app.UnifiedTargetName(unified_group)
+            # Use the unified_group determined by target.py
+            self.build_command = app.UnifiedTargetName(unified_group or 'main')
 
         if not enable_wifipaf:
             self.extra_gn_options.append(