feat(mcp): scaffold three project context tools

mcp_servers/project_context/__init__.py

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+"""Provider-neutral Project Context MCP server template."""
+
+from .server import build_server, dispatch
+
+__all__ = ["build_server", "dispatch"]

mcp_servers/project_context/foundation.py

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+"""Shared, stable boundary used by all Project Context tool work packages."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from dataclasses import dataclass
+from datetime import datetime
+from typing import Any, Protocol
+
+from pydantic import AnyUrl, BaseModel, ConfigDict, Field
+
+
+class ContractModel(BaseModel):
+    """Strict immutable model so provider-specific fields cannot leak to the Agent."""
+
+    model_config = ConfigDict(extra="forbid", frozen=True)
+
+
+class IdentityContext(ContractModel):
+    actor_id: str = Field(min_length=1, max_length=256)
+    org_unit: str = Field(min_length=1, max_length=128)
+    customer: str = Field(min_length=1, max_length=128)
+    project: str = Field(min_length=1, max_length=128)
+    granted_scopes: frozenset[str]
+
+
+class SourceCitation(ContractModel):
+    system: str = Field(min_length=1, max_length=64)
+    url: AnyUrl
+    revision: str = Field(min_length=1, max_length=256)
+    retrieved_at: datetime
+
+
+@dataclass(frozen=True)
+class DispatchResult:
+    ok: bool
+    payload: dict[str, Any]
+
+
+class PolicyDecisionPoint(Protocol):
+    def decide(self, identity: IdentityContext, tool_name: str, project_id: str) -> bool: ...
+
+
+class CredentialResolver(Protocol):
+    def resolve(self, identity: IdentityContext, tool_name: str) -> Any: ...
+
+
+@dataclass(frozen=True)
+class ProjectContextRuntime:
+    identity: IdentityContext
+    policy: PolicyDecisionPoint
+    credential_resolver: CredentialResolver
+
+
+class ProviderError(RuntimeError):
+    """A provider failure with a caller-safe message and retry classification."""
+
+    def __init__(self, code: str, message: str, *, retryable: bool) -> None:
+        super().__init__(message)
+        self.code = code
+        self.safe_message = message
+        self.retryable = retryable
+
+
+ToolHandler = Callable[[ContractModel, Any], dict[str, Any]]
+
+
+@dataclass(frozen=True)
+class ToolTemplate:
+    name: str
+    description: str
+    input_model: type[ContractModel]
+    output_model: type[ContractModel]
+    handler: ToolHandler
+
+    def declaration(self) -> dict[str, Any]:
+        return {
+            "name": self.name,
+            "description": self.description,
+            "inputSchema": self.input_model.model_json_schema(),
+            "outputSchema": self.output_model.model_json_schema(),
+        }
+
+
+def error_result(
+    code: str,
+    *,
+    category: str,
+    retryable: bool,
+    message: str,
+    suggested_action: str,
+    correlation_id: str,
+) -> DispatchResult:
+    return DispatchResult(
+        ok=False,
+        payload={
+            "error": {
+                "code": code,
+                "category": category,
+                "retryable": retryable,
+                "message": message,
+                "suggested_action": suggested_action,
+                "correlation_id": correlation_id,
+            }
+        },
+    )

mcp_servers/project_context/providers/__init__.py

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+"""One provider module per member-owned tool work package."""

mcp_servers/project_context/providers/change.py

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+"""Provider boundary owned with get_project_change_context."""
+
+from __future__ import annotations
+
+from typing import Any, Protocol
+
+from ..foundation import IdentityContext, ProviderError
+
+
+class ChangeProvider(Protocol):
+    def get_change_context(self, **arguments: Any) -> dict[str, Any]: ...
+
+
+class UnconfiguredChangeProvider:
+    def get_change_context(self, **arguments: Any) -> dict[str, Any]:
+        raise ProviderError(
+            "UNAVAILABLE",
+            "The change provider is not configured for this environment.",
+            retryable=False,
+        )
+
+
+def build_provider(identity: IdentityContext) -> ChangeProvider:
+    """Replace only this factory when wiring the approved read-only Git adapter."""
+    return UnconfiguredChangeProvider()

mcp_servers/project_context/providers/issue.py

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+"""Provider boundary owned with get_project_issue_context."""
+
+from __future__ import annotations
+
+from typing import Any, Protocol
+
+from ..foundation import IdentityContext, ProviderError
+
+
+class IssueProvider(Protocol):
+    def get_issue_context(self, **arguments: Any) -> dict[str, Any]: ...
+
+
+class UnconfiguredIssueProvider:
+    def get_issue_context(self, **arguments: Any) -> dict[str, Any]:
+        raise ProviderError(
+            "UNAVAILABLE",
+            "The issue provider is not configured for this environment.",
+            retryable=False,
+        )
+
+
+def build_provider(identity: IdentityContext) -> IssueProvider:
+    """Replace only this factory when wiring the approved read-only issue adapter."""
+    return UnconfiguredIssueProvider()

mcp_servers/project_context/providers/knowledge.py

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+"""Provider boundary owned with search_project_knowledge."""
+
+from __future__ import annotations
+
+from typing import Any, Protocol
+
+from ..foundation import IdentityContext, ProviderError
+
+
+class KnowledgeProvider(Protocol):
+    def search_knowledge(self, **arguments: Any) -> dict[str, Any]: ...
+
+
+class UnconfiguredKnowledgeProvider:
+    def search_knowledge(self, **arguments: Any) -> dict[str, Any]:
+        raise ProviderError(
+            "UNAVAILABLE",
+            "The knowledge provider is not configured for this environment.",
+            retryable=False,
+        )
+
+
+def build_provider(identity: IdentityContext) -> KnowledgeProvider:
+    """Replace only this factory when wiring approved project retrieval."""
+    return UnconfiguredKnowledgeProvider()

mcp_servers/project_context/registry.py

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+"""Immutable registry composed before member work starts to prevent merge conflicts."""
+
+from __future__ import annotations
+
+from types import MappingProxyType
+from typing import Any
+
+from .foundation import ToolTemplate
+from .tools.change_context import TOOL as CHANGE_CONTEXT_TOOL
+from .tools.issue_context import TOOL as ISSUE_CONTEXT_TOOL
+from .tools.knowledge_search import TOOL as KNOWLEDGE_SEARCH_TOOL
+
+TOOLS: tuple[ToolTemplate, ...] = (
+    ISSUE_CONTEXT_TOOL,
+    KNOWLEDGE_SEARCH_TOOL,
+    CHANGE_CONTEXT_TOOL,
+)
+TOOLS_BY_NAME = MappingProxyType({tool.name: tool for tool in TOOLS})
+TOOL_NAMES = tuple(tool.name for tool in TOOLS)
+
+
+def tool_declarations() -> list[dict[str, Any]]:
+    return [tool.declaration() for tool in TOOLS]

mcp_servers/project_context/runtime.py

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+"""Fail-closed identity, policy, and provider resolution for the template server."""
+
+from __future__ import annotations
+
+import os
+import sys
+from collections.abc import Callable
+from dataclasses import dataclass
+from typing import Any
+
+from .foundation import IdentityContext, ProjectContextRuntime, ProviderError
+from .providers.change import build_provider as build_change_provider
+from .providers.issue import build_provider as build_issue_provider
+from .providers.knowledge import build_provider as build_knowledge_provider
+
+MINIMUM_PYTHON = (3, 11)
+
+
+def require_supported_python(version_info: tuple[int, ...] | None = None) -> None:
+    """Fail with an actionable message before the MCP server starts."""
+    current = version_info or tuple(sys.version_info[:3])
+    if current[:2] < MINIMUM_PYTHON:
+        raise RuntimeError(
+            "Project Context MCP requires Python 3.11 or newer; "
+            f"current runtime is {current[0]}.{current[1]}"
+        )
+
+
+@dataclass(frozen=True)
+class ProjectScopePolicy:
+    """Pilot policy: read scope and exact identity-bound project are both mandatory."""
+
+    def decide(self, identity: IdentityContext, tool_name: str, project_id: str) -> bool:
+        return "read" in identity.granted_scopes and project_id == identity.project
+
+
+PROVIDER_FACTORIES: dict[str, Callable[[IdentityContext], Any]] = {
+    "get_project_issue_context": build_issue_provider,
+    "search_project_knowledge": build_knowledge_provider,
+    "get_project_change_context": build_change_provider,
+}
+
+
+@dataclass(frozen=True)
+class ProjectProviderResolver:
+    def resolve(self, identity: IdentityContext, tool_name: str) -> Any:
+        factory = PROVIDER_FACTORIES.get(tool_name)
+        if factory is None:
+            raise ProviderError("NOT_FOUND", "The requested tool is not registered.", retryable=False)
+        return factory(identity)
+
+
+def _required_environment(name: str) -> str:
+    value = os.environ.get(name, "").strip()
+    if not value:
+        raise RuntimeError(f"Project Context MCP cannot start: required setting {name} is missing")
+    return value
+
+
+def default_runtime() -> ProjectContextRuntime:
+    """Build immutable runtime state; missing identity configuration fails at boot."""
+    require_supported_python()
+    identity = IdentityContext(
+        actor_id=_required_environment("COWORK_MCP_ACTOR_ID"),
+        org_unit=_required_environment("COWORK_MCP_ORG_UNIT"),
+        customer=_required_environment("COWORK_MCP_CUSTOMER"),
+        project=_required_environment("COWORK_MCP_PROJECT"),
+        granted_scopes=frozenset({"read"}),
+    )
+    return ProjectContextRuntime(
+        identity=identity,
+        policy=ProjectScopePolicy(),
+        credential_resolver=ProjectProviderResolver(),
+    )

mcp_servers/project_context/server.py

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+"""Low-level MCP stdio adapter around the transport-agnostic Project Context core."""
+
+# ruff: noqa: UP045 -- Optional keeps the template importable with Pydantic on Python 3.9.
+
+from __future__ import annotations
+
+import json
+from typing import Any, Optional
+from uuid import uuid4
+
+from pydantic import ValidationError
+
+from .foundation import (
+    DispatchResult,
+    ProjectContextRuntime,
+    ProviderError,
+    error_result,
+)
+from .registry import TOOLS_BY_NAME, tool_declarations
+from .runtime import default_runtime, require_supported_python
+
+
+def dispatch(
+    name: str,
+    arguments: dict[str, Any],
+    runtime: ProjectContextRuntime,
+) -> DispatchResult:
+    """Validate → authorize → resolve provider → execute → validate output."""
+    correlation_id = str(uuid4())
+    tool = TOOLS_BY_NAME.get(name)
+    if tool is None:
+        return error_result(
+            "NOT_FOUND",
+            category="NOT_FOUND",
+            retryable=False,
+            message="The requested MCP tool is not registered.",
+            suggested_action="Refresh the tool list and choose one of the advertised tools.",
+            correlation_id=correlation_id,
+        )
+
+    try:
+        validated_input = tool.input_model.model_validate(arguments or {})
+    except ValidationError:
+        return error_result(
+            "INVALID_INPUT",
+            category="INVALID_INPUT",
+            retryable=False,
+            message="The tool arguments do not match the published input contract.",
+            suggested_action="Correct the required fields and value bounds, then call again.",
+            correlation_id=correlation_id,
+        )
+
+    project_id = str(validated_input.project_id)
+    if not runtime.policy.decide(runtime.identity, name, project_id):
+        return error_result(
+            "DENIED",
+            category="DENIED",
+            retryable=False,
+            message="The project is outside the caller's approved scope.",
+            suggested_action="Use an approved project or ask the project owner for access.",
+            correlation_id=correlation_id,
+        )
+
+    try:
+        provider = runtime.credential_resolver.resolve(runtime.identity, name)
+        raw_output = tool.handler(validated_input, provider)
+    except ProviderError as exc:
+        return error_result(
+            exc.code,
+            category=exc.code,
+            retryable=exc.retryable,
+            message=exc.safe_message,
+            suggested_action="Check the approved provider configuration and retry if allowed.",
+            correlation_id=correlation_id,
+        )
+    except Exception:  # noqa: BLE001 - provider failures must not crash or leak into the agent turn
+        return error_result(
+            "UPSTREAM_ERROR",
+            category="UPSTREAM_ERROR",
+            retryable=False,
+            message="The approved provider could not complete the request.",
+            suggested_action="Check the correlation ID in server logs; do not resend credentials.",
+            correlation_id=correlation_id,
+        )
+
+    try:
+        output_with_trace = {**raw_output, "correlation_id": correlation_id}
+        validated_output = tool.output_model.model_validate(output_with_trace)
+    except ValidationError:
+        return error_result(
+            "UPSTREAM_ERROR",
+            category="UPSTREAM_ERROR",
+            retryable=False,
+            message="The provider response did not match the published output contract.",
+            suggested_action="Fix the provider mapping before retrying the request.",
+            correlation_id=correlation_id,
+        )
+    return DispatchResult(ok=True, payload=validated_output.model_dump(mode="json"))
+
+
+def build_server(runtime: Optional[ProjectContextRuntime] = None):
+    from mcp import types
+    from mcp.server.lowlevel import Server
+
+    require_supported_python()
+    app_runtime = runtime or default_runtime()
+    app = Server("project_context")
+
+    @app.list_tools()
+    async def list_tools() -> list[types.Tool]:
+        return [types.Tool(**declaration) for declaration in tool_declarations()]
+
+    @app.call_tool()
+    async def call_tool(name: str, arguments: dict[str, Any]) -> types.CallToolResult:
+        result = dispatch(name, arguments or {}, app_runtime)
+        return types.CallToolResult(
+            content=[types.TextContent(
+                type="text",
+                text=json.dumps(result.payload, ensure_ascii=False, separators=(",", ":")),
+            )],
+            structuredContent=result.payload if result.ok else None,
+            isError=not result.ok,
+        )
+
+    return app
+
+
+def main() -> None:
+    import anyio
+    from mcp.server.stdio import stdio_server
+
+    app = build_server()
+
+    async def _run() -> None:
+        async with stdio_server() as (read, write):
+            await app.run(read, write, app.create_initialization_options())
+
+    anyio.run(_run)
+
+
+if __name__ == "__main__":
+    main()

mcp_servers/project_context/tools/__init__.py

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+"""Independent tool modules; ownership is documented in the team guide."""

mcp_servers/project_context/tools/change_context.py

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+"""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,
+)

mcp_servers/project_context/tools/issue_context.py

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+"""Member A work package: get_project_issue_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 IssueContextInput(ContractModel):
+    project_id: str = Field(min_length=1, max_length=128)
+    issue_key: str = Field(min_length=1, max_length=128)
+    detail: Literal["summary", "standard", "full"] = "standard"
+    cursor: Optional[str] = Field(default=None, max_length=2048)
+
+
+class RelatedItem(ContractModel):
+    item_id: str
+    relation: str
+    title: str
+    url: str
+
+
+class IssueContextOutput(ContractModel):
+    correlation_id: str
+    project_id: str
+    issue_key: str
+    title: str
+    status: str
+    description: str
+    acceptance_criteria: tuple[str, ...]
+    related: tuple[RelatedItem, ...]
+    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 = IssueContextInput.model_validate(arguments)
+    return provider.get_issue_context(**request.model_dump())
+
+
+TOOL = ToolTemplate(
+    name="get_project_issue_context",
+    description=(
+        "Returns one authorized work item's title, state, description, acceptance criteria, "
+        "related items, and pinned source. Use when an exact issue key is known. Do not use for "
+        "free-text knowledge search or Git change review."
+    ),
+    input_model=IssueContextInput,
+    output_model=IssueContextOutput,
+    handler=_handle,
+)

mcp_servers/project_context/tools/knowledge_search.py

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+"""Member B work package: search_project_knowledge."""
+
+# 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 KnowledgeSearchInput(ContractModel):
+    project_id: str = Field(min_length=1, max_length=128)
+    query: str = Field(min_length=2, max_length=1000)
+    detail: Literal["summary", "standard", "full"] = "standard"
+    top_k: int = Field(default=5, ge=1, le=20)
+    language: Optional[Literal["en", "ja", "vi"]] = None
+    cursor: Optional[str] = Field(default=None, max_length=2048)
+
+
+class KnowledgeItem(ContractModel):
+    document_id: str
+    chunk_id: str
+    title: str
+    excerpt: str
+    score: float = Field(ge=0, le=1)
+    source: SourceCitation
+
+
+class KnowledgeSearchOutput(ContractModel):
+    correlation_id: str
+    project_id: str
+    query: str
+    items: tuple[KnowledgeItem, ...]
+    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 = KnowledgeSearchInput.model_validate(arguments)
+    return provider.search_knowledge(**request.model_dump())
+
+
+TOOL = ToolTemplate(
+    name="search_project_knowledge",
+    description=(
+        "Searches approved knowledge for one authorized project and returns ranked excerpts with "
+        "pinned citations. Use for requirements, design notes, or runbooks when no exact issue is "
+        "known. Do not use for issue details or Git change review."
+    ),
+    input_model=KnowledgeSearchInput,
+    output_model=KnowledgeSearchOutput,
+    handler=_handle,
+)