The CLI stream mixin and the gateway think filter each carried a hand-copied think-tag
tuple guarded by a "must stay in sync" comment; adding a tag meant three edits. The
scrubber (agent/think_scrubber.py) now exports THINK_OPEN_TAGS/THINK_CLOSE_TAGS and both
consumers (and strip_think_blocks' regexes) bind to them.
acp_adapter/tools.py::_TITLE_BUILDERS hand-rolled 25 per-tool titles that
agent/display.build_tool_preview already produces (with redaction). ACP titles are now
"<tool>: <preview>"; no ACP-specific overrides remained necessary.