080 body position expressions

✓ Passing This code compiles and runs correctly.

Code

// Test 210_080: body-position content without trailing `(...)` or `{...}`
// parses as an `.expression` Node, not as an invocation or branch_constructor.
//
// Lars's rule (locked 2026-05-24): invocations always have parens (or a
// Source-block `{`). Anything else at body position is a Zig expression.
//
// Shapes exercised here:
//  - string literal:      "Alice"
//  - integer literal:     42
//  - bare identifier:     reply
//  - arithmetic:          1 + 2

~pub event sample
! one []const u8 -> []const u8
! two []const u8 -> usize
! three []const u8 -> []const u8
! four []const u8 -> i32
| done

~sample()
! one _ |> "Alice"
! two _ |> 42
! three q |> q
! four _ |> 1 + 2
| done |> _
input.kz

Expected AST

{
  "module_annotations": [],
  "items": [
    {
      "type": "import_decl",
      "path": "$std/compiler",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 2,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 2,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 3,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 4,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 5,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 6,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 7,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 8,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 9,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 10,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 11,
        "col": 0
      }
    },
    {
      "type": "host_line",
      "module": "input",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 12,
        "col": 0
      }
    },
    {
      "type": "parse_error",
      "code": "PARSE003",
      "message": "event declaration missing input shape",
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 13,
        "col": 1
      },
      "raw_text": "~pub event sample\n! one []const u8 -> []const u8\n! two []const u8 -> usize\n! three []const u8 -> []const u8\n! four []const u8 -> i32\n| done\n\n"
    },
    {
      "type": "flow",
      "invocation": {
        "event": [
          "sample"
        ],
        "args": [],
        "variant": null
      },
      "continuations": [
        {
          "branch": "one",
          "kind": "effect",
          "is_catchall": false,
          "binding": "_",
          "binding_type": "branch_payload",
          "condition": null,
          "step": {
            "type": "expression",
            "expression": "\"Alice\""
          },
          "continuations": []
        },
        {
          "branch": "two",
          "kind": "effect",
          "is_catchall": false,
          "binding": "_",
          "binding_type": "branch_payload",
          "condition": null,
          "step": {
            "type": "expression",
            "expression": "42"
          },
          "continuations": []
        },
        {
          "branch": "three",
          "kind": "effect",
          "is_catchall": false,
          "binding": "q",
          "binding_type": "branch_payload",
          "condition": null,
          "step": {
            "type": "branch_constructor",
            "branch_constructor": {
              "branch_name": "q",
              "fields": [],
              "plain_value": null,
              "has_expressions": false
            }
          },
          "continuations": []
        },
        {
          "branch": "four",
          "kind": "effect",
          "is_catchall": false,
          "binding": "_",
          "binding_type": "branch_payload",
          "condition": null,
          "step": {
            "type": "expression",
            "expression": "1 + 2"
          },
          "continuations": []
        },
        {
          "branch": "done",
          "kind": "terminal",
          "is_catchall": false,
          "binding": null,
          "binding_type": "branch_payload",
          "condition": null,
          "step": {
            "type": "terminal"
          },
          "continuations": []
        }
      ],
      "pre_label": null,
      "post_label": null,
      "impl_of": null,
      "location": {
        "file": "tests/regression/200_COMPILER_FEATURES/210_PARSER/210_080_body_position_expressions/input.kz",
        "line": 21,
        "col": 0
      }
    }
  ]
}

Test Configuration

PARSER_TEST
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