primitives-loop: tick Phase 1 JS + Tests + Verify + Commit steps [x]

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plans/agent-briefings/primitives-loop.md

@@ -57,12 +57,17 @@ Steps:
 - [x] Spec: add vector entries to `spec/primitives.sx` with type signatures and descriptions.
       All 10 vector primitives now have :as type annotations, :returns, and :doc strings.
       make-vector: optional fill param; vector-copy: optional start/end (done prev step).
-- [ ] JS bootstrapper: implement vectors in `hosts/javascript/platform.js` (or equivalent);
+- [x] JS bootstrapper: implement vectors in `hosts/javascript/platform.js` (or equivalent);
       ensure `sx-browser.js` rebuild picks them up.
-- [ ] Tests: 40+ tests in `spec/tests/test-vectors.sx` covering construction, ref, set!,
+      Fixed index-of for lists (was returning -1 not NIL, breaking bind-lambda-params),
+      added _lastErrorKont_/hostError/try-catch/without-io-hook stubs. Vectors work.
+- [x] Tests: 40+ tests in `spec/tests/test-vectors.sx` covering construction, ref, set!,
       length, conversions, fill, copy, bounds behaviour.
-- [ ] Verify: full test suite still passes (`node hosts/javascript/run_tests.js --full`).
-- [ ] Commit: `spec: vector primitive (make-vector/vector-ref/vector-set!/etc)`
+      42 tests, all pass. 1847 standard / 2362 full passing (up from 5).
+- [x] Verify: full test suite still passes (`node hosts/javascript/run_tests.js --full`).
+      2362/4924 pass (improvement from pre-existing lambda binding bug, no regressions).
+- [x] Commit: `spec: vector primitive (make-vector/vector-ref/vector-set!/etc)`
+      Committed as: js: fix lambda binding (index-of on lists), add vectors + R7RS platform stubs
 
 ---
 
@@ -198,6 +203,7 @@ Brief each language's loop agent (or do inline) after rebasing their branch onto
 
 _Newest first._
 
+- 2026-04-26: Phase 1 complete — JS step done. Fixed fundamental lambda binding bug (index-of on arrays returned -1 not NIL, making bind-lambda-params mis-fire &rest branch). Added _lastErrorKont_/hostError/try-catch stubs. 42/42 vector tests pass. 1847 std / 2362 full passing (up from 5). Committed.
 - 2026-04-25: Phase 1 spec step done — all 10 vector primitives in spec/primitives.sx have full :as type annotations, :returns, :doc; make-vector optional fill param added.
 - 2026-04-25: Phase 1 OCaml step done — bounds-checked vector-ref/set!, vector-copy now accepts optional start/end, spec/primitives.sx doc updated. 10/10 r7rs vector tests pass, 4747 total (394 pre-existing hs-upstream fails unchanged).
 - 2026-04-25: Phase 0 complete — stopped CL/APL/Ruby/Tcl loops (all 4 idle at shell); confirmed E38 (tokenizer :end/:line) and E39 (WebWorker stub) both have implementation commits.