fix(adapters): wrap redacted MCP output in CallToolResult

[gzak]

Summary

• mcp_tool_interceptor was returning output_check.redacted_data (a plain str) when a redaction policy applied to an MCP tool result
• langchain-mcp-adapters expects the interceptor to return MCPToolCallResult (CallToolResult | ToolMessage | Command) and unconditionally accesses .content on the return value, causing AttributeError: 'str' object has no attribute 'content'
• Now wraps the redacted string in CallToolResult(content=[TextContent(type="text", text=...)]), which is the correct type for the interceptor contract
• Adds mcp>=1.0.0 as a new langgraph optional extra (pip install 'axonflow[langgraph]') and to dev dependencies
• Uses a lazy import with a clear ImportError message if mcp is not installed

Fixes #119

Test plan

• test_returns_redacted_data_when_present updated to assert the return is a CallToolResult with the correct TextContent
• All 15 TestMCPToolInterceptor tests pass
• Full suite: 631 passed, 22 skipped

[saurabhjain1592]

Good fix — the CallToolResult wrapping is correct and the Optional → X | None modernization is a nice cleanup.

CI is red because the test matrix in .github/workflows/ci.yml still includes 3.9:

python-version: ['3.9', '3.10', '3.11', '3.12']

The 3.9 job fails on requires-python >= 3.10, which triggers fail-fast and cancels the other jobs. Drop 3.9 from the matrix and it should go green.

Also check if release.yml has a similar matrix or 3.9 reference that needs updating.

[saurabhjain1592]

Two blocking issues before this can merge. The redaction fix itself is correct.

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[P1] Top-level mcp import makes the LangGraph adapter unusable without the extra

from mcp.types import CallToolResult, TextContent is now at module level in langgraph.py. This means from axonflow.adapters import AxonFlowLangGraphAdapter fails with ImportError unless mcp is installed, even for users who only use the workflow-gating parts of the adapter and never call mcp_tool_interceptor().

This is a regression from the current optional-dependency model and contradicts the PR description ("Uses a lazy import with a clear ImportError message if mcp is not installed").

Fix: move the mcp import inside mcp_tool_interceptor() or the redaction branch, and raise a helpful ImportError there instead.

---

[P1] Bugfix PR quietly drops advertised Python 3.9 support

pyproject.toml now sets requires-python = ">=3.10" and masfeat.py rewrites all types to X | None (3.10+ syntax), but the rest of the repo still advertises and tests 3.9. The PR's own test (3.9) job is already failing at install time: Package 'axonflow' requires a different Python: 3.9.25 not in '>=3.10'.

Dropping 3.9 is fine (it's EOL), but it should be an explicit, separate change with:

• CI matrix updated (.github/workflows/ci.yml and release.yml) to remove 3.9
• README compatibility section updated
• Release notes calling out the compatibility break

Recommendation: split this PR into two:

1. The CallToolResult bugfix (with lazy import) — can ship as a patch release
2. The Python 3.9 drop + Optional modernization — ships as a minor or major version bump

That way the bugfix isn't blocked on the compatibility discussion and users on 3.9 still get the fix.

[saurabhjain1592]

Two issues I'd strongly recommend fixing before merging. The redaction fix itself is correct.

---

[P1] Top-level mcp import breaks LangGraph adapter for users who don't have mcp installed

from mcp.types import CallToolResult, TextContent is now at module level in langgraph.py. This means from axonflow.adapters import AxonFlowLangGraphAdapter fails with ImportError unless mcp is installed, even for users who only use the workflow-gating parts of the adapter and never call mcp_tool_interceptor().

This is a regression from the current optional-dependency model and contradicts the PR description ("Uses a lazy import with a clear ImportError message if mcp is not installed").

Fix: move the mcp import inside mcp_tool_interceptor() or the redaction branch, and raise a helpful ImportError there instead.

---

[P1] Bugfix PR quietly drops advertised Python 3.9 support

pyproject.toml now sets requires-python = ">=3.10" and masfeat.py rewrites all types to X | None (3.10+ syntax), but the rest of the repo still advertises and tests 3.9. The PR's own test (3.9) job is already failing at install time: Package 'axonflow' requires a different Python: 3.9.25 not in '>=3.10'.

Dropping 3.9 is fine (it's EOL), but it should be an explicit, separate change with:

• CI matrix updated (.github/workflows/ci.yml and release.yml) to remove 3.9
• README compatibility section updated
• Release notes calling out the compatibility break

Recommendation: split this PR into two:

1. The CallToolResult bugfix (with lazy import) — can ship as a patch release
2. The Python 3.9 drop + Optional modernization — ships as a minor or major version bump

That way the bugfix isn't blocked on the compatibility discussion and users on 3.9 still get the fix.