go: parse.sx scaffold — primary expressions + Go precedence table + 17 tests [consumes-pratt consumes-ast]

Starts Phase 2. lib/go/parse.sx defines:
  * go-precedence-table — Go's five operator-precedence levels in the
    (NAME PREC ASSOC) entry shape from lib/guest/pratt.sx, ready for the
    binary-operator iteration to consume via pratt-op-lookup.
  * go-parse(src) — tokenises and parses ONE primary expression: int,
    float, imag, string, rune literals become (ast-literal VALUE);
    identifiers become (ast-var NAME). Built directly on lib/guest/ast.sx
    constructors — no intermediate AST shape.

Conformance.sh extended to load lib/guest/{ast,pratt}.sx and run the
new parse suite. Scoreboard cleanup: drop the "pending" parse row since
the suite is now real.

parse 17/17 (lex still 129/129). Total 146/146.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plans/go-on-sx.md

@@ -154,21 +154,28 @@ Progress-log line → push `origin/loops/go`.
   done** — hex floats deferred (rare). Move to Phase 2 next.
 
 ### Phase 2 — Parser (`lib/go/parse.sx`) ⬜
-- Consume `lib/guest/core/pratt.sx` + `lib/guest/core/ast.sx`. Chisel notes
-  `consumes-pratt consumes-ast`.
-- Grammar coverage:
-  - Declarations: `package`, `import`, `var`, `const`, `type`, `func`
-  - Types: basic, slice `[]T`, array `[N]T`, map `map[K]V`, chan `chan T`,
-    func `func(...)...`, struct, interface, pointer `*T`
-  - Expressions: literals, identifier, call, index `[]`, slice `[a:b]`,
-    type assertion `v.(T)`, operators
-  - Statements: `if`/`else`, `for` (C-style + range), `switch`, `select`,
-    `return`, `defer`, `go`, `break`/`continue`, assign, short-decl `:=`,
-    send `ch <- v`, recv `<-ch`
-- Output: SX-shaped AST per `lib/guest/core/ast.sx` conventions.
-- Tests: round-trip parse of hello world, fibonacci, FizzBuzz, goroutine
-  ping-pong, struct + method.
-- **Acceptance:** parse/ suite at 80+ tests.
+- [x] Parser scaffold + Go operator-precedence table (entry shape from
+      `lib/guest/pratt.sx`) + primary expressions (int/float/imag/string/
+      rune/ident → ast-literal / ast-var via `lib/guest/ast.sx`).
+- [ ] Binary operators (Pratt precedence climbing using
+      `pratt-op-lookup` + Go precedence table).
+- [ ] Unary operators (`!x`, `-x`, `^x`, `*p`, `&v`, `<-ch`).
+- [ ] Function calls `f(a, b)` and member access `x.field`.
+- [ ] Index `x[i]` and slice `x[a:b]`/`x[a:b:c]`.
+- [ ] Type assertion `v.(T)`.
+- [ ] Type expressions: basic, slice `[]T`, array `[N]T`, map `map[K]V`,
+      chan `chan T` / `chan<- T` / `<-chan T`, func, struct, interface,
+      pointer `*T`.
+- [ ] Composite literals: `T{...}`, `[]T{...}`, `map[K]V{...}`,
+      `struct{...}{...}`.
+- [ ] Declarations: `package`, `import`, `var`, `const`, `type`, `func`
+      (including methods, parameter lists, return types).
+- [ ] Statements: `if`/`else`, `for` (C-style + range), `switch` (expr +
+      type), `select`, `return`, `defer`, `go`, `break`/`continue`,
+      assign, short-decl `:=`, send `ch <- v`, recv `<-ch`.
+- [ ] End-to-end: hello-world, fibonacci, FizzBuzz, goroutine ping-pong,
+      struct + method.
+- **Acceptance:** parse/ suite at 80+ tests. Current: 17/17.
 
 ### Phase 3 — Bidirectional type checker, MVP (`lib/go/types.sx`) ⬜
 - **Independent implementation.** Do NOT use lib/guest/static-types-
@@ -427,6 +434,14 @@ Minimal repro: see `lib/go/lex.sx#gl-oct-digit?` and `#gl-match-op`.
 
 _Newest first. Append one dated entry per commit._
 
+- 2026-05-27 — Phase 2 first slice: `lib/go/parse.sx` parser scaffold.
+  Defines `go-precedence-table` using `lib/guest/pratt.sx` entry shape
+  `(NAME PREC ASSOC)` — five Go precedence levels, all left-associative
+  per Go spec § Operator precedence. `go-parse` tokenises via
+  `go-tokenize`, then `gp-parse-primary` reads one literal / identifier
+  and emits a canonical AST node via `lib/guest/ast.sx`'s `ast-literal`
+  / `ast-var`. parse 17/17, lex still 129/129, total 146/146.
+  `[consumes-pratt consumes-ast]`.
 - 2026-05-27 — **Phase 1 complete.** Operator-set audit: added missing
   `~` (Go 1.18+ generics type-set), exhaustive op coverage tests grouped
   by category. Two kit gaps observed and logged in Blockers: