host: five Project-panel bounds still cut text on UTF-16 units, so a dossier or a board card can carry half an emoji #2005

Implementation: FlyBot (ours) — PR follows within 24h. Do not pick up without a pickup-ok comment on this issue.

Written-by: FlyBot Lead
Claimed-by: FlyBot Lead
Claim-Id: 9ce27c65909b4c5c982d5f505017a3a6
Branch: dev/1-project-panel-code-point-cuts
Base: a989587
At: 2026-11-01T07:36:07Z

Implementation: FlyBot (ours) — PR follows within 24h. Do not pick up without a pickup-ok comment.

Written-by: FlyBot Lead

What happens

Five bounds in the Project surfaces still cut with String.prototype.slice, which counts UTF-16 units, so a cut that lands inside a surrogate pair leaves half an emoji in the answer. The Dossier panel and the board cards render � where the emoji was, and the half pair travels through the host/client JSON as an unpaired surrogate.

Live main a989587f, all slice(0, N) on a string the user or another home supplied:

The same file already does it right one line away: core/src/host/project-team.js:49 uses cut(text(room.name), 200).text (from #1981). That is the shape to copy.

Reproduction (node, the live-main expressions)

• assistant title 'a'.repeat(76) + '😀' + 'b'.repeat(10) → slice(0,77) + '…' = 78 units, isWellFormed() === false, one lone high surrogate, tail "aaaa\ud83d…"
• board oneLine: 'a'.repeat(199) + '😀tail' → 200 units, not well formed, tail "aaaaa\ud83d"
• board title: '## ' + 'a'.repeat(199) + '😀' → heading stripped, slice(0,200) → not well formed, tail "aaa\ud83d"
• dossier capped(name, 200): 'a'.repeat(199) + '😀' → 200 units, not well formed
• dossier memory.head: 'a'.repeat(3999) + '😀' → 4000 units, not well formed

With the bound moved back onto the code point (cut), the same inputs give 76 / 199 / 199 / 199 / 3999 units and are all well formed — the emoji is dropped whole, never halved.

Expected

Every one of those answers stays well formed. Use the shared cut() (core/src/shared/text-boundary.js, re-exported from core/src/host/text.js), not a manual slice — a slice on an already well-formed string is still wrong at the bound.

Scope

• the five sites above; capped() can call cut(...).text once and cover all its call sites.
• tests: one case per site in core/test/project-assistant.test.js, core/test/project-board.test.js, core/test/project-team.test.js — red first on live main, and each case must be able to fail alone (mutate one site, only its case goes red).
• generated files: all three sources have full-file mirrors under patches/ds-bot/files/src/host/, so run node scripts/ds-bot-patches.mjs generate and commit the mirrors it writes; never hand-edit them, and a second generate must be a no-op.
• no core/client.js change (these are host answers).
• changelog fragment.

Dedup

Searched open and closed issues on live main: the room-name bound in project-team.js was fixed by #1981 (cut(text(room.name), 200).text); #1916 and #1917 swept other host modules and list no project-* file; no open issue covers these five. In flight today, #1998 touches member-status.js / group-status.test.js and #2004 touches room-membership.js, so neither collides.