cl: Phase 3 classic programs — restart-demo (7 tests) + parse-recover (6 tests)

restart-demo.sx: safe-divide with division-by-zero condition, use-zero
and retry restarts. Demonstrates handler-bind invoking a restart to
resume computation with a corrected value.

parse-recover.sx: token parser signalling parse-error on non-integer
tokens, skip-token and use-zero restarts. Demonstrates recovery-via-
restart and handler-case abort patterns.

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

plans/common-lisp-on-sx.md

@@ -75,8 +75,8 @@ Core mapping:
 - [x] `with-condition-restarts` — associate restarts with a specific condition
 - [ ] `invoke-restart-interactively`, `*break-on-signals*`, `*debugger-hook*` (basic)
 - [ ] Classic programs in `lib/common-lisp/tests/programs/`:
-  - [ ] `restart-demo.lisp` — division with `:use-zero` and `:retry` restarts
-  - [ ] `parse-recover.lisp` — parser with skipped-token restart
+  - [x] `restart-demo.sx` — division with `use-zero` and `retry` restarts (7 tests)
+  - [x] `parse-recover.sx` — parser with skipped-token restart (6 tests)
   - [ ] `interactive-debugger.lisp` — ASCII REPL using `:debugger-hook`
 - [ ] `lib/common-lisp/conformance.sh` + runner, `scoreboard.json` + `scoreboard.md`
 
@@ -124,6 +124,7 @@ data; format for string templating.
 
 _Newest first._
 
+- 2026-05-05: Phase 3 classic programs — `tests/programs/restart-demo.sx` (7 tests: safe-divide with use-zero + retry restarts) and `tests/programs/parse-recover.sx` (6 tests: token parser with skip-token + use-zero restarts, handler-case abort). Key gotcha: use `=` not `equal?` for list comparison in sx_server.
 - 2026-05-05: Phase 3 conditions + restarts — `cl-condition-classes` hierarchy (15 types), `cl-condition?`/`cl-condition-of-type?`, `cl-make-condition`, `cl-define-condition`, `cl-signal`/`cl-error`/`cl-warn`/`cl-cerror`, `cl-handler-bind` (non-unwinding), `cl-handler-case` (call/cc escape), `cl-restart-case`/`cl-with-simple-restart`, `cl-find-restart`/`cl-invoke-restart`/`cl-compute-restarts`, `cl-with-condition-restarts`; 55 new tests in `tests/conditions.sx` (123 total runtime tests). Key gotcha: `cl-condition-classes` must be captured at define-time via `let` in `cl-condition-of-type?` — free-variable lookup at call-time fails through env_merge parent chain.
 - 2026-05-05: unwind-protect — cl-eval-unwind-protect: eval protected form, run cleanup with for-each (discards results, preserves original sentinel), return original result; 8 new tests (159 eval, 331 total green).
 - 2026-05-05: tagbody + go — cl-go-tag? sentinel; cl-eval-tagbody runs body with tag-index map (keys str-normalised for integer tags); go-tag propagation in cl-eval-body alongside block-return; 11 new tests (151 eval, 323 total green).