[deepnmr]

The declared Python 3.10 floor was already broken (the test suite imports tomllib), the mcp extra was unpinned so a 1.x resolve lacked MCPServer, every MCP tool failure reached the client as an opaque "Error executing tool", the Seedless kernels accepted non-finite Bloch vectors and mis-shaped waveforms with backend-dependent exceptions, and the sdist shipped repository-internal files.

• Raise requires-python to 3.11, pin mcp>=2.0,<3 and numpy>=2.0 / scipy>=1.13, add licence/classifier/URL metadata, and trim the sdist to what a builder needs.
• Add the MIT LICENSE and an optimalcontrol/py.typed marker.
• Surface MCP user errors through ToolError (the pinned ValueError text now reaches the model), reject n_seeds < 1 up front, and type the band argument as a BandSpec TypedDict so the tool schema documents its keys.
• Validate Seedless kernel inputs (Bloch-vector shape/finiteness, (n_steps, 2) waveform) before dispatch so both backends raise the same ValueError.
• Give ControlProblem.freeze a default of None and drop the boilerplate from the docs.
• Share the offset-operator dimension validation between grape and ensemble.
• Tests: tmp_path instead of /tmp, pinned match= on the Seedless rejections, parity tests assert the native extension is present, in-memory MCP client tests, failing-first kernel tests.

Validation: full native suite 288 passed (274 before + 14 new); NumPy fallback suite (full, minus the by-design Rust-only file) 273 passed, 15 deselected; Ruff and strict mypy clean; in-memory MCP probe shows the pinned messages for all four error cases; the new kernel tests fail against the original kernel (5 failed) and pass against the fix (18 passed); renaming the native .so makes the Bloch parity test fail at the new availability assert and restoring it turns it green again; maturin sdist contains none of .kbsi/, .github/, CLAUDE.md, AGENTS.md, .gitignore, .claude-plugin/, benchmarks/; the wheel carries py.typed, LICENSE, Requires-Python: >=3.11. Later waves of the same plan (lint/format adoption, Rust manifest, module split, example dedupe, direct tests, CI, docs) land on this branch as further commits.