MCP has no way to wait for a pipeline to finish

Problem

After pushing a change, agents often need to know when the resulting pipeline finishes, for example to confirm a deploy or check whether tests passed. The GitLab MCP server has get_pipeline, but no way to wait. Agents either call it in a loop, spending a call and context on each check, or fall back to a shell loop that polls the API with sleep.

Proposal

Add a way to wait for a pipeline to reach a finished state, for example:

• a wait_for_completion option on get_pipeline with a maximum wait time, returning when the pipeline succeeds, fails or is canceled, or when the wait time runs out, or
• a poll_after_seconds hint in get_pipeline responses for running pipelines, like get_duo_session already returns.

Open questions for engineering

• How long a single MCP call can reasonably stay open, and whether a hint is the safer option.
• Whether the same applies to jobs.

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