001 subflow inline body

// ============================================================================
// VERIFIED REGRESSION TEST - DO NOT MODIFY WITHOUT DISCUSSION
// ============================================================================
// Test: inline_body inside subflow_impl default handler
// Feature: When a transform (e.g. [expand]) sets inline_body on a flow inside
//          a subflow_impl, the emitter must emit the inline code instead of
//          generating a handler call. This tests that the default handler
//          emission path respects Flow.inline_body.
// Verifies: Subflow can use [expand] transforms with branching continuations
// ============================================================================

~import "$std/template"
~import "$std/io"

const std = @import("std");

// Template: check if value > 0, return tagged union
~std.template:define(name: "check_positive") {
    blk: {
        const Result = union(enum) {
            positive: struct { val: i32 },
            negative: void,
        };
        const __value: i32 = {{ expr }};
        if (__value > 0) {
            break :blk Result{ .positive = .{ .val = __value } };
        } else {
            break :blk Result{ .negative = {} };
        }
    }
}

// [expand] event with branches — produces inline_body + switch
~[norun|expand]pub event check_positive { expr: Expression }
| positive { val: i32 }
| negative {}

// Event to test
~event classify { input: i32 }
| result { output: i32 }

// Subflow: uses check_positive (an [expand] with inline_body) inside subflow_impl
// This is the key pattern — inline_body must work in the default handler path
~classify = check_positive(expr: input)
| positive p |> result { output: p.val }
| negative |> result { output: -1 }

// Helper to print
~event print_result { value: i32 }
| done {}

~proc print_result {
    std.debug.print("{}\n", .{value});
    return .{ .done = .{} };
}

// Test 1: positive value → should output 42
~classify(input: 42)
| result r |> print_result(value: r.output)
    | done |> _

// Test 2: negative value → should output -1
~classify(input: -5)
| result r |> print_result(value: r.output)
    | done |> _