fix: preserve _meta during ACP serialization

[PsiACE]

Fix: #18

[Copilot]

Pull Request Overview

This PR adds support for field aliases in Pydantic models, specifically to map the field_meta attribute to the _meta JSON field for RPC serialization. The change enables proper serialization/deserialization of metadata fields using the JSON-RPC convention.

Key changes:

• Added populate_by_name=True configuration to allow models to accept both field names and their aliases during instantiation
• Updated serialization to use by_alias=True to output JSON with aliased field names (_meta instead of field_meta)
• Modified schema generation to automatically inject custom BaseModel configuration

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/acp/schema.py	Adds custom BaseModel class with populate_by_name=True configuration to support field aliases
src/acp/utils.py	Updates serialize_params to use by_alias=True for proper JSON field name mapping
src/acp/connection.py	Updates response serialization to use aliases and additional JSON-safe options
scripts/gen_schema.py	Adds schema generation logic to automatically inject custom BaseModel configuration
tests/test_utils.py	Adds test coverage for alias serialization behavior
examples/echo_agent.py	Demonstrates usage of field_meta attribute with the new alias support

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[Copilot]

The loop continues after finding the first from pydantic import line, but it should break after processing. This will cause issues if there are multiple pydantic import lines, as subsequent iterations will try to insert the BaseModel class definition multiple times at different positions.

Suggested change

	if not line.startswith("from pydantic import "):
	continue
	imports = [part.strip() for part in line[len("from pydantic import ") :].split(",")]
	has_alias = any(part == "BaseModel as _BaseModel" for part in imports)
	has_config = any(part == "ConfigDict" for part in imports)
	new_imports = []
	for part in imports:
	if part == "BaseModel":
	new_imports.append("BaseModel as _BaseModel")
	has_alias = True
	else:
	new_imports.append(part)
	if not has_alias:
	new_imports.append("BaseModel as _BaseModel")
	if not has_config:
	new_imports.append("ConfigDict")
	lines[idx] = "from pydantic import " + ", ".join(new_imports)
	insert_idx = idx + 1
	lines.insert(insert_idx, "")
	lines.insert(insert_idx + 1, "class BaseModel(_BaseModel):")
	lines.insert(insert_idx + 2, " model_config = ConfigDict(populate_by_name=True)")
	lines.insert(insert_idx + 3, "")
	break
	if line.startswith("from pydantic import "):
	imports = [part.strip() for part in line[len("from pydantic import ") :].split(",")]
	has_alias = any(part == "BaseModel as _BaseModel" for part in imports)
	has_config = any(part == "ConfigDict" for part in imports)
	new_imports = []
	for part in imports:
	if part == "BaseModel":
	new_imports.append("BaseModel as _BaseModel")
	has_alias = True
	else:
	new_imports.append(part)
	if not has_alias:
	new_imports.append("BaseModel as _BaseModel")
	if not has_config:
	new_imports.append("ConfigDict")
	lines[idx] = "from pydantic import " + ", ".join(new_imports)
	insert_idx = idx + 1
	lines.insert(insert_idx, "")
	lines.insert(insert_idx + 1, "class BaseModel(_BaseModel):")
	lines.insert(insert_idx + 2, " model_config = ConfigDict(populate_by_name=True)")
	lines.insert(insert_idx + 3, "")
	break

[Copilot]

The conditions if not has_alias and if not has_config will always be False when the loop at line 235-240 already found BaseModel and converted it to the alias. Since line 232-233 check for existing alias/config, and lines 236-238 ensure the alias is added when BaseModel is found, these additional checks are redundant. The logic should either rely on the existing checks (lines 232-233) or simplify this section.

Suggested change

	has_alias = any(part == "BaseModel as _BaseModel" for part in imports)
	has_config = any(part == "ConfigDict" for part in imports)
	new_imports = []
	for part in imports:
	if part == "BaseModel":
	new_imports.append("BaseModel as _BaseModel")
	has_alias = True
	else:
	new_imports.append(part)
	if not has_alias:
	new_imports.append("BaseModel as _BaseModel")
	if not has_config:
	new_imports = []
	for part in imports:
	if part == "BaseModel":
	new_imports.append("BaseModel as _BaseModel")
	else:
	new_imports.append(part)
	# Ensure "BaseModel as _BaseModel" and "ConfigDict" are present
	if "BaseModel as _BaseModel" not in new_imports:
	new_imports.append("BaseModel as _BaseModel")
	if "ConfigDict" not in new_imports: