feat(kernel): R7b Swift walker — swift module, tree-sitter-swift 0.7.3 bump, swift default-routed (#1381)

Fifth R7b batch-3 port, checklist-first recipe
(docs/design/swift-kernel-port-checklist.md, 1,056 lines — the largest of the
arc, with a built-extractor-validated emission pin and a childForFieldName
truth table).

Grammar bump first, validated standalone: tree-sitter-wasms ^0.4.0 (ABI 13) →
crate 0.7.3 — with a provenance twist: the wasm is built from the CRATE
TARBALL's src/ (alex-pinkus keeps generated files off main and the
0.7.3-with-generated-files tag ships an older ABI-14 generation that can never
sha-match; grammar.json rules are JSON-equal; the tarball is byte-for-byte
what the kernel's cargo build compiles — table identity by construction).
Older crates evaluated and rejected: clean-parse shapes are byte-identical on
0.7.3 (53-line CST battery diff, all inert), so an older pin buys nothing and
loses the macro-era wins. Delta = error-set membership (63 old-error files
parse clean: swift-testing #expect, #Preview/#GET macros, package access,
typed throws — vapor 23.1%→9.3%; 21 NEW-only regressions in 3 probed
construct classes) + two gate-found categories: docstring boundaries near #if
directives (7 clean files, docstring-field-only — verified mechanically) and
array-literal-callee call refs (2 refs, 1 file). Every hunk classified via
the error-union rule + parked-ref↔edge ripple pairing.

Walker (the arc's biggest) centers on the #1020 DEDICATED property branch:
computed properties → property nodes with the getter walked under the
property (SwiftUI body), static let/var → constant/variable, stored → field,
decorator/type-annotation/@Siblings-attr-arg refs all attached to the
ENCLOSING TYPE, stored initializer calls attributed to the class. Preserved
bug-for-bug: the never-resolving 'parameter' field (zero param type refs,
zero signatures), present-false isAsync, open→internal visibility,
everything-is-extends inheritance (first type_identifier per specifier), no
instantiates refs ever, subscript reads as `calls arr`, `defer` as `calls
defer`, multi-case enum entries minting only the first case, /** */ block
docs ignored AND chain-breaking, init/deinit/subscript minting no nodes with
visitNode-routed bodies (calls → class, static reads → nothing), multi-
segment extension resolveName, sugar extension names, the #selector shapes,
and the value_argument label-forward skip. ONE fix found by the sweep (then
pinned in the fixture + checklist): the shared `assignment` shadow-prune case
is swift-live — declared-then-assigned `let X: T` prunes X as a value-ref
target.

Gates: sweeps 0-diff Alamofire 89/98, vapor 224/247, swift-nio 407/554
(--max-deferral 0.3 — swift error incidence is 9–27% on BOTH arms,
structural; every deferral count matches the survey's table exactly);
full-init dumps byte-identical ×3 (31.9k/20.7k/126.3k lines); the Alamofire
census reproduces property=348 (the #1020 number) on the kernel arm;
kernel-swift-parity suite (206-line torture + CRLF + the #if-between-enum-
cases defer fixture) + swift grammar-parity row; full suite 2,626 green ×2
under CODEGRAPH_KERNEL_EXPECT=1. DEFAULT_ROUTED += swift (14 langs).

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

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

@@ -610,7 +610,7 @@ 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. | ☑ |
 | dart, scala, lua, luau, r | dedicated files | T1 | crates.io (luau/r/scala: verify crate freshness vs our wasm) | Long-tail T1; port opportunistically after the big five. | ☐ |
 | kotlin | `languages/kotlin.ts` | T1½ | crates.io | Expect/actual pairing is synthesis-side (fine); extraction is clean but validate against a KMP repo. | ☐ |
-| swift | shared + dedicated branch | T1½ | crates.io | **Trap:** in-class property extraction lives in `tree-sitter.ts`'s DEDICATED branch, not `swift.ts` (#1020 — Alamofire went 0→348 props). Gate on Alamofire. | ☐ |
+| 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. | ☑ |
 | metal, cuda | dialects over the cpp grammar | **T2** (rides c/cpp) | crates.io (cpp) | **DONE (rides R7a)** — `.metal`/`.cu`/`.cuh` map to 'cpp' and their blanks run in the hoisted preParse (filePath rides along for the extension gates); hoist-parity pinned in kernel-ccpp-parity.test.ts + the metal/cuda suites. | ☑ |
 | objc | `languages/objc.ts` | T2 | crates.io | Rides the c-cpp trap family; RN bridge extraction feeds `rnCrossPlatformEdges` (synthesis-side, fine). | ☐ |