fallback-model.ts (1,696) folded into assistant-ui/tool/fallback-model/ with
three cohesive, self-contained leaf modules extracted (verbatim moves):
- types.ts (83) — the shared tool-view types/interfaces.
- format.ts (133) — pure value formatting/parsing (isRecord, compactPreview,
clampForDisplay, prettyJson, parseMaybeObject, unwrapToolPayload, numberValue,
contextValue, formatDurationSeconds).
- targets.ts (75) — url/path/preview detection + disclosure ids (looksLikeUrl,
findFirstUrl, hostnameOf, isPreviewableTarget, toolPart/GroupDisclosureId).
index.ts (1,434) keeps the tool-specific assembler (TOOL_META, titles, the count
machinery, subtitle/detail/diff, buildToolView) and re-exports the leaf modules,
so consumers importing `./fallback-model` are unchanged (folder index resolution)
— no importer or channel edits needed. The count/result/detail helpers reach
across each other around buildToolView, so they stay together to avoid a circular
split; the three leaves are the clean cut.
Behaviour-preserving: typecheck 0 errors, eslint clean, fallback-model test 24/26
(the 2 browser_navigate title failures are pre-existing on main — `hostnameOf`
intentionally includes the pathname; verified identical on the un-split file).
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