feat(search): add fuzzy subsequence matching

[xcha]

Summary / 摘要

Adds an opt-in fuzzy mode to @floatboat/nexus-plugin-search. Queries match as an ordered subsequence within a single line and carry an fzf-inspired relevance score; navigation, select-all, viewport highlighting and rendered table-cell highlights all follow fuzzy matches through the existing CodeMirror search pipeline.

Motivation / 背景与动机

Roadmap #17. Today a query like fbb cannot find foo bar baz — only literal, whole-word and regex modes exist. Implemented in-package (~130 lines) rather than adding a fuzzy library dependency, per GOVERNANCE §6.3.

• Issue:
• Roadmap (docs/ROADMAP.md): feat(core,react,vue,search,slash,toolbar): editor API, search, slash commands and toolbar enhancements #17 Fuzzy search → done
• OpenSpec change: openspec/changes/add-search-fuzzy

Changes / 变更内容

• packages/plugin-search:
  • SearchOptions.fuzzy, SearchMatch.score?, SearchPluginLabels.fuzzy? (additive only); new exported FuzzySearchQuery
  • Line-scoped subsequence matcher with a minimal-span alignment (forward pass + backward tighten), scored with match / word-boundary / camelCase / consecutive / gap-penalty / exact-case terms
  • FuzzyQueryHandler implements the CodeMirror search query-type protocol (nextMatch, prevMatch, matchAll, highlight, getReplacement), so fuzzy rides the standard search state field instead of a parallel UI
  • Panel: fuzzy toggle (localizable), mutual exclusion with regexp / wholeWord, replace toggle + row hidden while active
  • Fuzzy replace is find-only; getReplacement returns the matched text so a programmatically invoked replace is an identity transform rather than destructive
  • No new dependency: @codemirror/state is not declared here, editor state types are derived from @codemirror/view
• packages/plugin-search/test: 24 new tests (matcher scoring, line scope, CRLF, panel wiring, CM navigation, select-all, replace hiding, history recall, table highlights)
• docs/ROADMAP.md, docs/ROADMAP.zh.md: feat(core,react,vue,search,slash,toolbar): editor API, search, slash commands and toolbar enhancements #17 → done
• openspec/: proposal, plugin spec delta, tasks

Known trade-off: the fuzzy query-type protocol is not exported by @codemirror/search — only the runtime method names are stable. The handler is implemented against that shape and covered by integration tests that exercise the real commands. See the proposal's Design Notes for why subclassing SearchQuery was chosen over a parallel UI.

Testing / 测试

• Targeted suite: plugin-search 58/58 passing
• Typecheck clean: plugin-search, reference-plugins, electron-demo
• Full suite: 921 passed / 1 failed — the failure is pre-existing on main (apps/electron-demo/test/plugin-host-broker.test.ts:667, O_NONBLOCK is 0 on Windows); CI runs ubuntu-latest
• Build: ESM + d.ts clean; dist/ stays gitignored
• OpenSpec: openspec validate --strict not run — CLI is not installed locally
• Manual UI check in electron-demo: ✅ done, screenshots below — fuzzy toggle renders, fbb matches foo bar baz, camelCase boundaries score above mid-word matches, table cell highlights follow fuzzy spans, replace controls hide while fuzzy is active
• Repo CI: pending maintainer approval to run (fork PR from a first-time contributor)

Compliance / 合规自检

• CLA signed — signed when the bot prompted
• AI disclosure: the functional code in this PR was drafted with Claude Code. I reviewed it line by line and can walk through every decision in the proposal's Design Notes section.
• New dependencies: none (packages/plugin-search/package.json unchanged)
• No build artifacts committed
• No secrets / .env / personal vault data committed

Checklist / 自检清单

• Title follows Conventional Commits
• Public API changes update package README / types — no README exists for packages/plugin-search; types updated in-place, check:api does not cover this package
• Touched live-preview-table.ts — no, not touched
• New capability → OpenSpec proposal linked (add-search-fuzzy)
• Change aligns with project scope (GOVERNANCE.md §4)

Screenshots / Recordings

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All committers have signed the CLA.