feat(mcp): scaffold three project context tools

mcp_servers/project_context/tools/change_context.py

@@ -0,0 +1,55 @@
+"""Member C work package: get_project_change_context."""
+
+# ruff: noqa: UP045 -- Optional keeps Pydantic model evaluation compatible with Python 3.9.
+
+from __future__ import annotations
+
+from typing import Any, Literal, Optional
+
+from pydantic import Field
+
+from ..foundation import ContractModel, SourceCitation, ToolTemplate
+
+
+class ChangeContextInput(ContractModel):
+    project_id: str = Field(min_length=1, max_length=128)
+    change_id: str = Field(min_length=1, max_length=128)
+    detail: Literal["summary", "standard", "full"] = "standard"
+    cursor: Optional[str] = Field(default=None, max_length=2048)
+
+
+class ChangeContextOutput(ContractModel):
+    correlation_id: str
+    project_id: str
+    change_id: str
+    change_type: Literal["commit", "pull-request", "merge-request"]
+    title: str
+    state: str
+    summary: str
+    authors: tuple[str, ...]
+    files: tuple[str, ...]
+    commits: tuple[str, ...]
+    related_issues: tuple[str, ...]
+    source: SourceCitation
+    truncated: bool
+    returned: int = Field(ge=0)
+    remaining: int = Field(ge=0)
+    next_cursor: Optional[str] = None
+
+
+def _handle(arguments: ContractModel, provider: Any) -> dict[str, Any]:
+    request = ChangeContextInput.model_validate(arguments)
+    return provider.get_change_context(**request.model_dump())
+
+
+TOOL = ToolTemplate(
+    name="get_project_change_context",
+    description=(
+        "Returns provider-neutral context for one authorized commit, pull request, or merge request "
+        "with changed files, commits, related issues, and a pinned source. Use when an exact change "
+        "identifier is known. Do not use for issue details or free-text document search."
+    ),
+    input_model=ChangeContextInput,
+    output_model=ChangeContextOutput,
+    handler=_handle,
+)