Follow-up to the two cherry-picked contributor commits (#111571 gateway, #111576 Desktop),
which neutralized the same class with two different mechanisms: an invisible U+200B after
the `[` on the gateway path and a phrase replacement ("RESERVED CONTROL MARKER NEUTRALIZED")
on the Desktop path.
Both room-transcript builders now share one frame set (the mid-turn steer marker open/close,
the compaction handoff, runtime/system notes, planning-state and async-delegation frames —
the same openers agent/title_generator and agent/context_compressor already classify as
harness-authored, case-insensitive) and one visible relabel: the opener `[` becomes
`[member-quoted `. The peer still reads what the member wrote, but the exact trusted shape
the system prompt tells the model to honour is gone and the label says who authored it.
A zero-width space is invisible to a human reading the transcript and easy for a model to
skip over; the visible label is not.
Genuine user lines, stored room events and the displayed message are untouched on both
surfaces (probed live: stored member event byte-identical, `User (user):` line verbatim).
Tests trimmed to one invariant per surface, built from agent.prompt_builder's real marker
constants on the Python side.
Co-authored-by: KoNit-K <124019182+KoNit-K@users.noreply.github.com>
Co-authored-by: Hukla <129692708+huklaa@users.noreply.github.com>
teknium1
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