011 optional branch catchall

// ============================================================================
// Test 210_011: Optional Branch Catch-All |? Syntax (engaging forms only)
//
// Per the pay-for-nothing rule (docs/EFFECT_BRANCHES.md), bare-discard
// catch-alls (`|? |> _`, `|? Metatype _ |> _`) are parser-rejected:
// they opt into runtime cost (disabling comptime elision, routing every
// unhandled branch into a handler, building the metatype struct for
// metatype variants) while gaining zero information.
//
// This test now pins ONLY the engaging shapes — body does real work,
// optionally with metatype binding for tiered reflection.
// ============================================================================

const std = @import("std");

// Event with required and optional branches
~event process { value: u32 }
| success u32        // Required
| ?warning []const u8   // Optional
| ?debug []const u8 // Optional

~proc process|zig {
    return .{ .success = value };
}

~pub event observe { name: []const u8 }
~proc observe|zig {
    _ = name;
}

// Test 1: |? with Transition metatype binding, body does work
~process(value: 10)
| success _ |> _
|? Transition _ |> observe(name: "t1")

// Test 2: |? with Profile metatype binding, body does work
~process(value: 20)
| success _ |> _
|? Profile _ |> observe(name: "p2")

// Test 3: |? with Audit metatype binding, body does work
~process(value: 30)
| success _ |> _
|? Audit _ |> observe(name: "a3")

// Test 4: Mix explicit optional handling + engaging catch-all for the rest
~process(value: 40)
| success _ |> _
| warning _ |> _
|? Transition _ |> observe(name: "t4")

// Test 5: Catch-all with `_` binding but body does real work
~process(value: 50)
| success _ |> _
|? Transition _ |> observe(name: "discard-bind-real-body")