030 taps with auto discharge

// Library module: fs
// Phantom-tracked file operations for testing taps + auto-discharge

const std = @import("std");

const File = struct { handle: i32 };

// Open a file - returns opened! state (requires cleanup)
~pub event open { path: []const u8 }
| opened *File<opened!>

~proc open|zig {
    std.debug.print("Opening file\n", .{});
    const f = std.heap.page_allocator.create(File) catch unreachable;
    f.* = File{ .handle = 42 };
    return .{ .opened = f };
}

// Close - the ONLY consumer of [!opened]
~pub event close { file: *File<!opened> }

~proc close|zig {
    std.debug.print("Closing file (auto-discharged)\n", .{});
}

// A logging event for taps - can observe file handle from the tap binding
// The tap passes in the handle it observed from the opened event
~pub event log-open { handle: i32 }

~proc log-open|zig {
    // Note: Procs receive input via generated code, we just print a static message
    std.debug.print("TAP: Observed file open!\n", .{});
}