PR #2050 tri-review — Vue SFC dual-script merge & JS/TS routing

Methods (3): GitNexus reviewer swarm + Compound-Engineering personas (both Claude) and Codex (the one independent engine). Engine breakdown: 8 Claude lanes — correctness, adversarial, maintainability, testing, risk, test/CI, plus a Vue-SFC expert and a TypeScript/tree-sitter expert added at your request (risk & test/CI ended mid-investigation; their domains were covered by the other lanes) — and Codex live. Codex ran as a foreground, not-prompted-from-Claude-output call and independently confirmed all three headline findings. Note on independence: the two Claude methods share priors, so Claude-only agreement is "consistent across personas," not independent confirmation; the strong signal here is Codex + a Claude lane + a reproduction.

What's solid (validated — credit where due): the extractVueScript merge logic and the new lang field work as intended on the sequential (<15-file) path, and the extractor unit tests pass. Two suspected problems were refuted and excluded (validation is a feature): (a) feeding a TS-grammar cached tree into emitJsScopeCaptures does not corrupt captures — it is guarded by jsCachedTreeMatchesGrammar and re-parsed; (b) the F89 lineOffset doc change is accurate — countNewlines(precedingText)+1 is genuinely 1-based and the consumer math (+ node 0-based row) is correct, no off-by-one introduced.

Headline (P1 — reproduced)

For a .vue with an explicit <script lang="js"> block followed by a <script setup lang="ts"> block, extractVueScript merges both and returns lang = blocks[0].lang = 'js', so emitVueScopeCaptures routes the combined JS+TS text to the JavaScript grammar. Reproduced with the repo's pinned grammars on that merged content: tree-sitter-javascript → 1 ERROR + 1 missing node, the interface fails to parse; tree-sitter-typescript → 0 errors, clean. This is a regression — before this PR only the <script setup> (TS) block was extracted and parsed as TS. (Trigger needs an explicit lang="js"; an absent lang routes to TS and is safe.) Codex and the adversarial lane independently confirmed/reproduced it.

Inline findings

• [P1] captures.ts:74 / vue-sfc-extractor.ts:269 — mixed-lang merged content routed to one grammar via blocks[0].lang (the headline above).
• [P2] captures.ts:62-63 — setupLang is read but never set by any caller (the bridge passes only { sourceKind }; the LanguageProvider contract type omits it; repo-wide grep finds zero setters). So in worker mode (≥15 files — the large-repo path this branch targets) every .vue routes to emitTsScopeCaptures, silently losing the JS-only passes (CJS require() decomposition, JSDoc type-bindings). Not a crash and not a regression vs base — but F92's routing fix doesn't reach the worker path, and the comment "the parse worker passes langs via sourceMeta.setupLang" is actively misleading.
• [P2] vue-sfc-extractor.ts:266 — lineOffset = blocks[0].lineOffset uses source order while combinedContent is built from ordered (non-setup first); divergent when <script setup> precedes <script>, and the single-newline join collapses the inter-block gap so the second block's lines are off regardless. Affects user-visible line numbers (jump-to-line / call-site annotations), not graph topology.
• [P2/P3] new fixtures — vue-dual-script/App.vue and vue-js-lang/App.vue are referenced by no test and lack the src/ mini-repo layout the integration suite uses; their natural home is test/integration/resolvers/vue-scope.test.ts (which currently runs only vue-composition-api / vue-options-api / vue-cross-file).

Lower-priority / notes

• Absent lang="" routes to TS even though Vue's default script lang is JS — harmless (TS is a superset) but plain <script> JS also misses the JS-only passes; consider routing '' | 'js' | 'jsx' → JS.
• lang="jsx"/"tsx" (newly advertised in the doc) route to the non-JSX TS grammar (grammar is chosen by the .vue extension) → JSX would ERROR-node. Pre-existing; consider trimming the doc claim.
• Stale doc: languages/vue/index.ts:40-42 still says "only <script setup> is processed… the non-setup block is skipped" — contradicts the new merge (that file is not in this diff).
• Comment at vue-sfc-extractor.ts:267-268 ("the template compiler will catch it") — GitNexus never runs the Vue template compiler; mismatched-lang blocks are silently mis-parsed here.

Test gaps

No test exercises the worker (pre-extracted-script) routing, the full-pipeline JS-lang or dual-script paths (the new fixtures would, if wired), <script setup>-before-<script> ordering, or symbol line numbers for merged blocks. The merge test asserts presence (toContain) but not order.

CI: all green except Vercel (deploy authorization, not a code issue) — typecheck/lint/tests/coverage pass. Coverage of this review: the full 5-file diff was read and the headline reproduced; the PR head moved mid-review (a main merge bringing in unrelated MCP work, #2049) but no Vue file changed, so these findings apply to the current head.

Automated multi-tool digest (GitNexus swarm + Compound-Engineering personas + Codex). Verify before acting; inline anchors mark the most load-bearing lines.