feat(mcp): expose thread model selection

[juliusmarminge]

Part 7/16 of the shared-core and MCP stack. Based on #10556. Next: #10558.

Read thread configuration and change the calling thread provider/model/options through existing selection and switch commands.

This intentionally limits writes to the caller. Permission-mode changes, cross-thread configuration and multi-command retry transactions are separate work. Provider/model discovery already exists in orchestrator_capabilities.

The command choice is now shared with client-runtime through modelSelectionCommandType; MCP does not maintain a separate provider comparison.

MCP-only rebuild of #8695, preserving attribution to Julius Marminge's original work. Original branches remain available for separate service follow-ups.

Validation: The composed stack passes 94 tests across 12 focused files, including shared core MCP and real MCP/V2 integration, attachment intake, project RPC/service contracts, and client model command selection. Server/contracts/shared/client-runtime typechecks and targeted format/lint/diff checks pass. New behavior coverage lives with the shared operation; no per-tool mock suite was added. Current-head CI is shown below.

Layer size: 4 files, +59/-0. No domain-service production implementation or documentation files change in this MCP layer.

Prepared with Codex in the OpenAI agent runtime.

Note

Add t3_thread_configuration and t3_thread_configure MCP tools for thread model selection

• Adds a read-only t3_thread_configuration tool that returns the calling thread's ID, model selection, runtime mode, and interaction mode
• Adds a destructive t3_thread_configure tool that dispatches a model-selection command to the current writable thread without changing permission modes or other threads
• Registers both tools in ThreadToolkit, adds t3_thread_configuration to the Claude read-only allowlist, and adds display-name entries in the T3 MCP presentation map
• Risk: t3_thread_configure opens the current thread for writing and dispatches a command; callers that invoke it concurrently may interleave sequence numbers. Reviewers should check ThreadToolkitHandlersLive configure handler in handlers.ts for dispatch and error-mapping behavior

^{Macroscope summarized b0152bc.}

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR adds new MCP tools, including a mutating tool that changes the calling thread's model or provider and can invoke existing provider-switch orchestration. The implementation is localized, but the new MCP dispatch branches lack direct behavioral coverage, so the change warrants human review.

Notes:

• Diff unchanged. Approvability was decided on eligibility alone.

No code changes detected at b0152bc. Prior analysis still applies.

^{You can add or adjust custom eligibility rules. Learn more.}

[github-actions]

Thread transfer impact

⚠️ The latest CI run did not produce a thread transfer result for b0152bc.

This comment will update automatically after the next completed run.

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