Task: Implement Hotfix: fix the main CI failures

(Describe what user-visible-or-internal change this task produces.)

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)

Every number this task claims about a tree, with the command that produced it and the commit it was measured at. A number without both is not a measurement, because a clean-up record describes a tree and trunk moves under a branch: a consumer count, a gate's component count and a suite's size all change with no code changing, and the reader of a bare number cannot tell which tree it came from. Where the raw output matters, put it in an evidence/ file beside the task and name that file in the Command column.

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The four CI failures on main are fixed in commit 438ed5e525. The gcc loop in xml_document_tests.cpp copies each string. The generator emits stable_arena for the recursive arenas of wide records, so MSVC no longer sees a std::deque of an incomplete type. client::disconnect waits for the closed callback, so the callback no longer locks a destroyed mutex. The two id links in the time-series plot capture are uppercase. Only CI proves the gcc, MSVC and workflow results.