Add coding symbol rail

src/tui.zig

@@ -4,6 +4,7 @@ const leader_mod = @import("leader.zig");
 const protocol = @import("protocol.zig");
 const replay = @import("replay.zig");
 const session_mod = @import("session.zig");
+const symbol_mod = @import("symbol.zig");
 
 // First terminal thin client surface, scriptable for E2E-style tests.
 // req: session/001, session/003, ui/001, coding/001, testing/001, testing/002
@@ -180,6 +181,7 @@ pub const Client = struct {
                 defer self.allocator.free(line);
                 try self.applyProtocol(line);
             },
+            .symbol => |symbol| try self.applyProtocol(symbol_mod.protocolCommand(symbol)),
             .not_built => {},
         }
     }
@@ -414,3 +416,54 @@ test "adversarial: unknown leader input recovers without saving or quitting" {
     try std.testing.expect(!client.quit);
     try std.testing.expectError(Error.NothingSaved, client.saved());
 }
+
+fn expectSymbolTrace(symbol_key: []const u8, expected_bytes: []const u8, expected_cursor_byte: usize) !void {
+    var client = try Client.init(std.testing.allocator, .{ .width = 64, .height = 4 });
+    defer client.deinit();
+
+    try client.handleTraceLine("open base");
+    try client.handleTraceLine("key space");
+    try client.handleTraceLine("key p");
+    const rail = try client.render(std.testing.allocator);
+    defer std.testing.allocator.free(rail);
+    try std.testing.expect(std.mem.indexOf(u8, rail, "symbols:") != null);
+
+    const line = try std.fmt.allocPrint(std.testing.allocator, "key {s}", .{symbol_key});
+    defer std.testing.allocator.free(line);
+    try client.handleTraceLine(line);
+
+    const snap = try client.session.snapshot();
+    try std.testing.expectEqualStrings(expected_bytes, snap.bytes);
+    try std.testing.expectEqual(expected_cursor_byte, snap.cursor_byte);
+}
+
+test "regular: symbol rail inserts paired braces brackets parens and quotes with cursor inside" {
+    try expectSymbolTrace("p", "()base", 1);
+    try expectSymbolTrace("b", "[]base", 1);
+    try expectSymbolTrace("c", "{}base", 1);
+    try expectSymbolTrace("q", "\"\"base", 1);
+    try expectSymbolTrace("e", "''base", 1);
+    try expectSymbolTrace("t", "``base", 1);
+}
+
+test "regular: symbol rail inserts slash pipe and underscore as single symbols" {
+    try expectSymbolTrace("s", "/base", 1);
+    try expectSymbolTrace("v", "|base", 1);
+    try expectSymbolTrace("u", "_base", 1);
+}
+
+test "adversarial: unknown symbol key does not mutate the buffer" {
+    var client = try Client.init(std.testing.allocator, .{ .width = 64, .height = 4 });
+    defer client.deinit();
+
+    try client.handleTraceLine("open base");
+    try client.handleTraceLine("key space");
+    try client.handleTraceLine("key p");
+    try client.handleTraceLine("key ?");
+
+    const snap = try client.session.snapshot();
+    try std.testing.expectEqualStrings("base", snap.bytes);
+    const frame = try client.render(std.testing.allocator);
+    defer std.testing.allocator.free(frame);
+    try std.testing.expect(std.mem.indexOf(u8, frame, "unknown symbol key") != null);
+}