[TheGreatAxios]

Summary

• NoticeState drops its dead interrupt field: the shell writes it, composeNoticeLine never reads it
• The byte-identical oneLine()/abbreviate() collapse helpers share one implementation
• gapRows computes once in a shared MarkdownSplit builder used by both split paths
• The redundant agentName !== undefined null check is gone — first derives from agentName?.[0]
• The nested ternaries in the at-mention path lister become small if-blocks

Verification

• bun test over the co-located suites (notice-line, copy-path, tool-formatter, tool-formatter-web-brand, markdown-parser, at-mention/list): 177 pass, 0 fail
• bun run typecheck passes; oxfmt --check and oxlint pass on the seven changed files
• Item 1: interrupt is unread — grep finds no state.interrupt read in composeNoticeLine or anywhere in src/tui; the field and the shell/chrome.ts assignment are removed
• Item 2: oneLine(text, max=56) and abbreviate(value, max) are identical (replace(/\s+/g," ").trim(), then slice(0, max-1) + "…" when over max); both call sites share the same max-1 ellipsis; copy-path now calls abbreviate(payload.text, 56)
• Item 3: splitAtSettledHeading and splitAtSettledBlock both derive firstContent from rest.findIndex((line) => line.trim().length > 0); both now build through settledSplit
• Item 4: first = agentName?.[0], so first != null already implies a non-empty agentName; the extra agentName !== undefined check is redundant and removed (branch text unchanged)
• Item 5: nested ternaries at list.ts:42-43 and 59-68 are replaced with behavior-identical if-blocks

Fixes CL-10529

[linear-code]

CL-10529

[corbits-triage]

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