Migrate to the mcp 2.0 server API (closes #20)

[linsamtw]

Summary

Ports server.py off the mcp 1.x decorator API and drops the mcp<2.0.0 ceiling that 0.0.6 added as a stopgap (#18 / #16). mcp>=2.0.0 from here.

Everything below was verified against a real mcp==2.0.0 install, not from memory.

What mcp 2.0 actually changed

1. Handler registration moved to the constructor. The lowlevel Server still exists; @app.list_tools() is replaced by Server("finmind", on_list_tools=..., on_call_tool=..., on_list_resources=..., on_read_resource=...). Handlers take (ctx, params) and return full result models (ListToolsResult, CallToolResult, …) instead of bare lists.
2. Every type field is snake_case now, with camelCase kept as the JSON alias: inputSchema → input_schema, isError → is_error, mimeType → mime_type. This reaches tools.py and knowledge.py, not just server.py. The wire format is unchanged — verified below.

The one behaviour that needed restoring by hand

A raising call_tool handler	mcp 1.x	mcp 2.0
becomes	CallToolResult(isError=true) — the model sees the message and can retry	a JSON-RPC protocol error — the host reports a server failure

tools.dispatch raises only on an unknown tool name (everything else is already rendered as a 繁中 message), so the blast radius is narrow — but a purely mechanical port would have silently downgraded that path. on_call_tool now catches and returns is_error=True itself, and tests/test_server.py has a test whose only job is to keep it that way.

Verification

Unit tests — tests/test_server.py is new; server.py previously had zero unit coverage, and the handlers are now plain async functions that need no subprocess:

uv run --extra dev pytest -q          →  39 passed  (was 32)
uv run --python 3.10 pytest -q        →  39 passed  (3.10 floor holds)
uv run python smoke.py                →  SMOKE OK
uv run python chatgpt/build_instructions.py →  OK (7987/8000 chars)

End-to-end over real stdio JSON-RPC, checking the raw frames rather than the SDK's own view:

protocolVersion: 2024-11-05        ← old-protocol hosts still handshake fine
tool keys:       ['description', 'inputSchema', 'name']    ← camelCase intact
call keys:       ['content', 'isError']
unknown tool  →  result with isError: true   (NOT a protocol error)
resource keys:   [..., 'mimeType', ...]

mcp 2.0 accepts handshakes from 2024-11-05 through the new 2026-07-28, so existing Claude Desktop / Cursor / Gemini CLI configs keep working.

Not done here

smoke.py and regression/runner.py needed no changes — they speak raw JSON-RPC and are version-agnostic. Worth one manual run in a real host before tagging.

Release: the dependency floor crosses a major version, so 0.1.0 reads better than 0.0.7 — tag is yours to push.

🤖 Generated with Claude Code