feat(kernel): R7b Scala walker — scala module, vendored-grammar-C master@0aca5d0a6f, scala default-routed (#1385)

R7b batch 4 #3 (docs/design/scala-kernel-port-checklist.md is the
authoritative quirk list). The third vendored-grammar-C language and the
biggest grammar in the tree (35MB parser.c): the vendored wasm is
tree-sitter/tree-sitter-scala master@0aca5d0a6f — a post-v0.26.0 generation
sync that is not a release (the 0.26.0 crate is 30 states BEHIND, so a
crate pin would be a silent downgrade). NO wasm change: production has
parsed with this exact revision since #91 — the kernel-grammar-parity row
(ABI 15, 26,650 states, 32 fields, id-by-id tables) is the whole alignment
proof.

Preserved bug-for-bug (all probe-pinned): the leak-through asymmetries —
extension methods mint NO nodes (first def's body calls leak to the
enclosing scope, later defs invisible, and the braced form resolves its
body field to the `{` TOKEN via first-match-wins field lookup → whole
extension invisible); anonymous `new T { … }` template_body members leak to
the enclosing scope (findAnonymousClassBody misses template_body); the
bodied-vs-bodiless class asymmetry (bodiless headers walk class_parameters
→ default-value calls emit FROM the class; bodied ones never see them) —
plus first-segment import names (`import com.example.C` → `com`), the
val/var hook keyed on the enclosing-definition NODE TYPE (object vals →
constants/value-ref targets, class/trait/enum/given vals → fields) with
consumed initializers, every def routed through extractMethod with the
top-level function fallback, nested defs in bodies minting NOTHING (the
inverse of kotlin) while body-local classes extract fully, curried
signatures keeping only the FIRST parameter list (type params win the
`parameters` field), enum cases positioned at the CASE node with invisible
params/extends tails, extends with-chains via scalaBaseTypeName,
`@deprecated(args)` decorates, the #750 capitalized-chain re-encode
(`WidgetS.create().render`), literal-receiver silence, static-member reads
AND writes, infix invisibility, `derives` silence, scaladoc retention with
the CRLF `\r` pin, full value-reference machinery (shadow prune, last-wins
same-name targets, `$X`/`${X}` interpolation reads), and SCALA_SPEC
fn-refs (bare ids + postfix eta unwrap + varinit, var-init non-capture).

Gates: parity sweeps first-run 0-diff on os-lib/cats/scala3-compiler-src/
scala3-library-src — 1,935 clean files byte-parity, deferrals 0/15/57/116
matching the survey's predictions exactly (scala-3's PHANTOM hasError
files — flag-true, zero ERROR nodes, capture-checking `^` — defer on the
FLAG); full-init dumps byte-identical ×3 (os-lib, cats, scala3 whole-repo
950,889 dump lines); kernel-scala-parity suite (9 fixtures + 9 in-memory
CRLF variants incl. Scala-3 indentation through the external scanner +
phantom/real-error defer pins + first-segment/namespace/value-ref pins);
full suite 2,669 green ×3 with CODEGRAPH_KERNEL_EXPECT=1
(kernel-scaffold's stays-wasm example moved scala → pascal).
DEFAULT_ROUTED += scala (19 langs).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/design/rust-kernel-migration-plan.md

@@ -610,7 +610,8 @@ parity before porting the language.
 | rust | `languages/rust.ts` | T1 | crates.io | **DONE (R7b #1, 2026-07-20)** — `rustlang.rs` walker; grammar bumped to v0.24.2 (crate + vendored wasm together). Parity 0-diff on ripgrep/tokio/rust-analyzer + dump byte-identical ×3; rust-analyzer's parser crates defer 18% (token-macro tables, both-arm parse errors — grammar-inherent). Quirk list: docs/design/rust-lang-kernel-port-checklist.md. | ☑ |
 | r | `languages/r.ts` | T1 | crates.io | **DONE (R7b batch 4 #1, 2026-07-20)** — `rlang.rs` walker; NO grammar change (crate pin `=1.2.0`: the crates.io tarball ships parser.c AND scanner.c sha-identical to the r-lib v1.2.0 tag the vendored wasm was built from — first true no-op grammar prep). The lightest-shared-surface, heaviest-hook port: r.ts works entirely through visitNode (every type list empty but `callTypes`), four shared machineries dead by language gates, walker = file node + hook transcription + generic extractCall. Parity 0-diff on AnomalyDetection/dplyr/ggplot2/shiny (838 files, deferrals 0/0/0/1 — the 1 = a moustache-template pseudo-R file, both-arm) + dump byte-identical ×3 (dplyr/ggplot2/shiny). kernel-parity.mjs gained lowercased-extension matching (`.R` is the dominant casing). Quirk list: docs/design/r-kernel-port-checklist.md. | ☑ |
 | lua, luau | `languages/lua.ts` + `luau.ts` (36-line extension) | T1 | lua: **vendored C** (v0.4.1 not on crates.io); luau: crates.io `=1.2.0` (tag≡crate sha-verified) | **DONE (R7b batch 4 #2, 2026-07-20)** — ONE walker (`lua.rs`, ccpp-style dialect flag); lua = the second vendored-grammar-C language (v0.4.1 tag artifacts, shas in the checklist); luau = plain crate pin. NO wasm change for either — grammar-parity rows replace the bump gate. Ports the require/visitNode-hook asymmetries (top-level imports vs body `calls "require"`), receiver-QN methods, the top-level initializer-visibility inversion, raw-text callee world (colon/bracket/glue chains, paren-conversion), LUA_SPEC fn-ref capture, LuaDoc `- `-keeping docstrings, and the lua↔luau isExported wire divergence. Parity 0-diff kong/lazy.nvim/lua-resty-core/lune/Fusion (1,734 clean files; deferrals 1/0/0/3/8 — every one matching the survey's both-arm predictions) + dump byte-identical ×4 (kong 157,650 dump lines). Quirk list: docs/design/lua-luau-kernel-port-checklist.md. | ☑ |
-| dart, scala | dedicated files | T1 | **vendored C** (revs not on crates.io — batch-4 probe) | Long-tail T1, surveys COMPLETE 2026-07-20 (checklists in docs/design/). dart = tree-sitter-wasms artifact byte-copy re-vendor + UserNobody14 d4d8f3e vendored-C (sibling-body double-walk is the port hazard); scala = master 0aca5d0a6f vendored-C (35MB parser.c; phantom-hasError dominant on scala-3). | ☐ |
+| scala | `languages/scala.ts` | T1 | **vendored C** (master@0aca5d0a6f — not a release; crate 0.26.0 is 30 states behind) | **DONE (R7b batch 4 #3, 2026-07-20)** — `scala.rs` walker; the third vendored-grammar-C language (35MB parser.c — the biggest grammar in the tree). NO wasm change (production has parsed with this exact revision since #91) — the grammar-parity row is the whole alignment proof. Ports the leak-through asymmetries (extension first-def call leak + braced-form invisibility via the `{`-token body field, anon `new T {…}` template_body member leaks, bodied-vs-bodiless class_parameters), first-segment import names, the val/var hook's enclosing-NODE-TYPE kinds, defs-as-methods with top-level function fallback, nested-def invisibility, curried/type-params-first signatures, the #750 capitalized re-encode, static-member WRITES, scaladoc retention, full value-refs (last-wins targets) + SCALA_SPEC fn-refs (varinit + postfix eta). Parity 0-diff os-lib/cats/scala3-compiler-src/scala3-library-src (1,935 clean files; deferrals 0/15/57/116 — every count matching the survey exactly; scala-3 PHANTOM hasError deferred on the flag) + dump byte-identical ×3 (scala3 whole-repo 950,889 dump lines). Quirk list: docs/design/scala-kernel-port-checklist.md. | ☑ |
+| dart | `languages/dart.ts` | T1 | **vendored C** (UserNobody14 d4d8f3e — reached via tree-sitter-wasms' unpinned github dep) | Long-tail T1, survey COMPLETE 2026-07-20 (docs/design/dart-kernel-port-checklist.md). Port = vendored-C + byte-copy the tree-sitter-wasms wasm artifact into src/extraction/wasm/ (kills the unpinned-dep hazard). The sibling-body DOUBLE-WALK (duplicate ids, ×3 refs) is the port hazard; sweeps --max-deferral 0.3. | ☐ |
 | kotlin | `languages/kotlin.ts` | T1½ | **vendored C** (crate unusable) | **DONE (R7b #6, 2026-07-20)** — `kotlin.rs` walker; the arc's FIRST vendored-grammar-C language: fwcd 0.3.8's sha-matched parser.c/scanner.c compile inside codegraph-kernel via build.rs + cc (the crates.io crate pins tree-sitter <0.23; tree-sitter-kotlin-ng is a different grammar). Behavior-neutral wasm re-vendor (dumps byte-identical old-vs-new ×3). Two walker firsts: extension-fn receiver QNs + owner-contains, and extractModifiers→decorators (KMP expect/actual — 412 synthesized edges identical both arms on kotlinx.coroutines). Parity 0-diff okio/okhttp/kotlinx.coroutines (1,861 clean files; deferral 4.7–8.5% both-arm incl. PHANTOM hasError files). Quirk list: docs/design/kotlin-kernel-port-checklist.md. | ☑ |
 | swift | shared + dedicated branch | T1½ | crates.io | **DONE (R7b #5, 2026-07-20)** — `swift.rs` walker incl. the #1020 dedicated property branch (Alamofire's 348 property nodes reproduced exactly on the kernel arm); grammar bumped to crate 0.7.3 (wasm built from the CRATE TARBALL's src — the tag ships an older ABI-14 generation; delta = error-set membership + 2 gate-found categories, all classified). Parity 0-diff Alamofire/vapor/swift-nio (720 clean files; deferral 9–27% both-arm structural — sweeps use --max-deferral 0.3). One walker fix found by the sweep: the shared `assignment` shadow-prune case is swift-live (declared-then-assigned `let X: T`). Quirk list: docs/design/swift-kernel-port-checklist.md. | ☑ |
 | c, cpp | `languages/c-cpp.ts` | **T2** | crates.io | **DONE (R7a, 2026-07-17)** — `ccpp/` walker; ALL pre-passes stayed TS-side via the route-point preParse hoist (+6 new blanks added during gating — see the checklist doc); content-based `.h` C-vs-C++ detection stays upstream at detectLanguage. Parity 0-diff + dump byte-identical on redis/git/fmt/protobuf/ALS. | ☑ |