fix: Require MCP compatible with current Pydantic

[buildingjoshbetter]

Scope

Follow-up to #757 and draft #773. Restore the minimum-MCP installed-wheel gate after an independently released Pydantic update exposed an upstream private-import dependency. No MCP tool behavior or model configuration changes.

Reproduction and root cause

The same TrueMemory source and MCP 1.19.0 passed with Pydantic 2.13.5/core 2.46.5, then failed at import mcp with Pydantic 2.14.0/core 2.50.0, before importing TrueMemory. MCP 1.21.0 also failed. MCP 1.21.1 passed with both Pydantic versions.

MCP imported the private pydantic._internal._typing_extra.eval_type_backport utility removed in Pydantic 2.14. MCP upstream fix, MCP 1.21.1 release, Pydantic removal.

Changes

• Require mcp[cli]>=1.21.1,<2.0 and update the minimum-version wheel lanes.
• Retain minimum/latest MCP checks across Linux, macOS and Windows, plus Python 3.10.
• Add explicit MCP 1.21.1 with Pydantic 2.11.0 and 2.14.0 cases. Other dependencies use normal resolution; this is not a claim of full minimum-transitive support.
• Mirror dependency checks in the release gate, without triggering publication.
• Emit only public package versions before the wheel smoke test, preserving its existing provenance, console, protocol and privacy assertions.

Validation

The isolated Linux dependency A/B matrix used actual CLI help/version and the existing stdio protocol assertions: initialize, 11 tools, six alwaysLoad entries, and directive schema. It was source-based, so rebuilt-wheel verification remains separate.

A freshly built and installed wheel passed the existing full MCP smoke test on Python 3.12.15 with MCP 1.30.0 and Pydantic 2.13.5. Log SHA256: eb50f64ec0acd7f1fc83d988fc225f4230d46046286ef05bfbfadb3c3582538f.

Ruff, Python 3.10 syntax, YAML parsing, all 13 expanded CI/release requirement branches, diagnostic negative control, and changed-content/commit-identity scans passed. Existing smoke-test helper bodies are unchanged.

Clean hosted installed-wheel boundary checks now pass at ebd35e44441663a74ebc8d30c29202eab887cf57:

• Python 3.10.22, MCP 1.21.1, Pydantic 2.11.0/core 2.33.0.
• Python 3.12.15, MCP 1.21.1, Pydantic 2.14.0/core 2.50.0.

Both logs show pip check and actual isolated installed-wheel protocol success. Other hosted jobs remain pending at this update. The remote minimum-pair smoke also passed, but its pip check failed because the reused image contained an unrelated SDK2 companion requiring newer Pydantic. That failed environment check remains recorded; the clean hosted environment supplies the lower-bound compatibility evidence.

No models loaded, personal fixtures used, main merge, tag or package release performed. Issue #757 remains open until integration gates pass.