diff --git a/src/tui/expansion.zig b/src/tui/expansion.zig
new file mode 100644
index 0000000..721509f
--- /dev/null
+++ b/src/tui/expansion.zig
@@ -0,0 +1,166 @@
+/// Expand variables in arg
+/// {{project}} - The path to the current project directory
+/// {{file}} - The path to the current file
+/// {{line}} - The line number of the primary cursor
+/// {{column}} - The column of the primary cursor
+/// {{selection}} - The current selection of the primary cursor
+/// {{selections}} - All current selections seperated by NL characters
+/// {{selectionsZ}} - All current selections separated by NULL characters
+/// {{selections*}} All current selections expanded to multiple quoted arguments
+pub fn expand(allocator: Allocator, arg: []const u8) Error![]const u8 {
+    var result: std.Io.Writer.Allocating = .init(allocator);
+    defer result.deinit();
+    var iter = arg;
+
+    while (iter.len > 0) {
+        const pos_begin = std.mem.indexOf(u8, iter, var_begin_mark) orelse {
+            try result.writer.writeAll(iter);
+            break;
+        };
+        try result.writer.writeAll(iter[0..pos_begin]);
+        iter = iter[pos_begin + var_begin_mark.len ..];
+
+        const pos_end = std.mem.indexOf(u8, iter, var_end_mark) orelse {
+            try result.writer.writeAll(iter);
+            break;
+        };
+        const var_name = iter[0..pos_end];
+        iter = iter[pos_end + var_end_mark.len ..];
+
+        const func = variables.get(var_name) orelse {
+            std.log.err("unknown variable '{s}'", .{arg});
+            return error.NotFound;
+        };
+        const text = try func(allocator);
+        defer allocator.free(text);
+        try result.writer.writeAll(text);
+    }
+    return try result.toOwnedSlice();
+}
+
+pub fn expand_cbor(allocator: Allocator, args_cbor: []const u8) ![]const u8 {
+    var result: std.Io.Writer.Allocating = .init(allocator);
+    defer result.deinit();
+    var iter = args_cbor;
+    var len = try cbor.decodeArrayHeader(&iter);
+    try cbor.writeArrayHeader(&result.writer, len);
+    while (len > 0) : (len -= 1) {
+        var arg: []const u8 = undefined;
+        if (try cbor.matchValue(&iter, cbor.extract(&arg))) {
+            const expanded = try expand(allocator, arg);
+            defer allocator.free(expanded);
+            try cbor.writeValue(&result.writer, expanded);
+        } else {
+            if (try cbor.matchValue(&iter, cbor.extract_cbor(&arg)))
+                try result.writer.writeAll(arg);
+        }
+    }
+    return try result.toOwnedSlice();
+}
+
+const var_begin_mark = "{{";
+const var_end_mark = "}}";
+
+pub const Error = error{
+    OutOfMemory,
+    WriteFailed,
+    NotFound,
+};
+const variables = std.StaticStringMap(Function).initComptime(get_functions());
+
+const functions = struct {
+    pub fn project(allocator: Allocator) Error![]const u8 {
+        return try allocator.dupe(u8, tp.env.get().str("project"));
+    }
+
+    pub fn file(allocator: Allocator) Error![]const u8 {
+        const mv = tui.mainview() orelse return &.{};
+        const ed = mv.get_active_editor() orelse return &.{};
+        return allocator.dupe(u8, ed.file_path orelse &.{});
+    }
+
+    pub fn line(allocator: Allocator) Error![]const u8 {
+        const mv = tui.mainview() orelse return &.{};
+        const ed = mv.get_active_editor() orelse return &.{};
+        var stream: std.Io.Writer.Allocating = .init(allocator);
+        try stream.writer.print("{d}", .{ed.get_primary().cursor.row + 1});
+        return stream.toOwnedSlice();
+    }
+
+    pub fn column(allocator: Allocator) Error![]const u8 {
+        const mv = tui.mainview() orelse return &.{};
+        const ed = mv.get_active_editor() orelse return &.{};
+        var stream: std.Io.Writer.Allocating = .init(allocator);
+        try stream.writer.print("{d}", .{ed.get_primary().cursor.col + 1});
+        return stream.toOwnedSlice();
+    }
+
+    pub fn selection(allocator: Allocator) Error![]const u8 {
+        const mv = tui.mainview() orelse return &.{};
+        const ed = mv.get_active_editor() orelse return &.{};
+        const sel = ed.get_primary().selection orelse return &.{};
+        return allocator.dupe(u8, ed.get_selection(sel, allocator) catch &.{});
+    }
+
+    pub fn selections(allocator: Allocator) Error![]const u8 {
+        const mv = tui.mainview() orelse return &.{};
+        const ed = mv.get_active_editor() orelse return &.{};
+        var results: std.Io.Writer.Allocating = .init(allocator);
+        for (ed.cursels.items) |*cursel_| if (cursel_.*) |*cursel| {
+            const sel = cursel.selection orelse continue;
+            const text = ed.get_selection(sel, allocator) catch return error.WriteFailed;
+            defer allocator.free(text);
+            try results.writer.writeAll(text);
+            try results.writer.writeByte('\n');
+        };
+        return try results.toOwnedSlice();
+    }
+
+    pub fn selectionsZ(allocator: Allocator) Error![]const u8 {
+        const mv = tui.mainview() orelse return &.{};
+        const ed = mv.get_active_editor() orelse return &.{};
+        var results: std.Io.Writer.Allocating = .init(allocator);
+        for (ed.cursels.items) |*cursel_| if (cursel_.*) |*cursel| {
+            const sel = cursel.selection orelse continue;
+            const text = ed.get_selection(sel, allocator) catch return error.WriteFailed;
+            defer allocator.free(text);
+            try results.writer.writeAll(text);
+            try results.writer.writeByte(0);
+        };
+        return try results.toOwnedSlice();
+    }
+
+    // pub fn @"selections*"(allocator: Allocator) Error![][]const u8 {
+    //     const mv = tui.mainview() orelse return &.{};
+    //     const ed = mv.get_active_editor() orelse return &.{};
+    //     var results: std.ArrayList([]const u8) = .empty;
+    //     for (ed.cursels.items) |*cursel_| if (cursel_.*) |*cursel| {
+    //         const sel = cursel.selection orelse continue;
+    //         (try results.addOne(allocator)).* = ed.get_selection(sel, allocator);
+    //     };
+    //     return results.toOwnedSlice(allocator);
+    // }
+};
+
+fn get_functions() []struct { []const u8, Function } {
+    comptime switch (@typeInfo(functions)) {
+        .@"struct" => |info| {
+            var count = 0;
+            for (info.decls) |_| count += 1;
+            var funcs: [count]FunctionDef = undefined;
+            for (info.decls, 0..) |decl, i|
+                funcs[i] = .{ decl.name, &@field(functions, decl.name) };
+            return &funcs;
+        },
+        else => @compileError("expected tuple or struct type"),
+    };
+}
+
+const Function = *const fn (allocator: Allocator) Error![]const u8;
+const FunctionDef = struct { []const u8, Function };
+
+const std = @import("std");
+const Allocator = @import("std").mem.Allocator;
+const tp = @import("thespian");
+const cbor = @import("cbor");
+const tui = @import("tui.zig");