Split control messages by scope: the root ctl takes the session's builtins and reads the settings, a pane's ctl its own

Every builtin could only be clicked, or written to exec, and the settings
could be read only as the Config window's prose. acme keeps window verbs on
a window's ctl, and webfs and upas/fs keep session settings on a root ctl.
Each builtin now declares its scope (scope = .session; settings are all
session, the rest pane), read by the registry. The root /ctl takes session
builtins and reads every setting in the words a write takes, so its read
written back changes nothing (panel and scene effects now take on/off like
the toggles, to make that true); a pane's ctl takes the pane's builtins
beside get, lock and unlock. Writes are checked whole and refused in Plan
9's ctl words (unknown control message "X", wrong #args ...), which 9ns
now maps to EINVAL (cloud9 re-pinned at a8c7a715). A builtin that would
prompt for its argument fails the write instead, and a refusal is answered
at once, not after the frame.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 56 insertions, 3 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index ffb00ff6..ed0a07dd 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -30,6 +30,14 @@ pub const capabilities: config.Runtime.Capabilities = .{
     .ligatures = pardes.platform == .gui,
 };
 
+/// Where a builtin acts: at the pane it runs from, or on the editor as a
+/// whole. acme keeps its window verbs on a window's ctl and its session
+/// commands elsewhere, as webfs and upas/fs keep session settings on a root
+/// ctl; pardes's root `ctl` takes the session builtins and a pane's `ctl`
+/// the pane ones. A builtin says `pub const scope: Scope = .session;`,
+/// and every setting is one; the rest act on their pane.
+pub const Scope = enum { pane, session };
+
 pub const Ctx = struct {
     p: *Pardes,
     pane: *Pane,
@@ -133,9 +141,14 @@ pub const registry = struct {
     pub fn takesArg(b: Builtin()) bool {
         inline for (manualBuiltinList(), 0..) |T, i|
             if (@intFromEnum(b) == i) return @hasDecl(T, "takes_arg") and T.takes_arg;
-        inline for (comptime settingList(), manualBuiltinCount()..) |setting, i|
-            if (@intFromEnum(b) == i) return setting.takesArg();
-        unreachable;
+        // Every setting takes its value, and a switch flips when bare.
+        return true;
+    }
+
+    pub fn scope(b: Builtin()) Scope {
+        inline for (manualBuiltinList(), 0..) |T, i|
+            if (@intFromEnum(b) == i) return if (@hasDecl(T, "scope")) T.scope else .pane;
+        return .session; // a setting
     }
 
     pub fn outputTraits(b: Builtin()) ?OutputTraits {
@@ -173,6 +186,17 @@ test "capabilities exactly gate setting and effect-source builtins" {
     try std.testing.expectEqual(EffectCode.enabled, effect_code_registered);
 }
 
+test "a builtin's scope is the pane unless it says session, and every setting is the session's" {
+    const Builtin = registry.Builtin();
+    try std.testing.expectEqual(Scope.pane, registry.scope(Builtin.Del));
+    try std.testing.expectEqual(Scope.pane, registry.scope(Builtin.Save));
+    try std.testing.expectEqual(Scope.session, registry.scope(Builtin.Newcol));
+    try std.testing.expectEqual(Scope.session, registry.scope(Builtin.Kill));
+    try std.testing.expectEqual(Scope.session, registry.scope(Builtin.Verbose));
+    for (comptime settingList()) |setting|
+        try std.testing.expectEqual(Scope.session, registry.scope(std.meta.stringToEnum(Builtin, setting.word).?));
+}
+
 test "Look does not announce itself on the message row; Del still does" {
     const Builtin = registry.Builtin();
     try std.testing.expect(!registry.announces(Builtin.Look));
@@ -233,6 +257,7 @@ pub const Exec = struct {
 // ---- session ----
 
 pub const Kill = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         c.p.quit = true;
         c.p.emit(.quit);
@@ -240,12 +265,14 @@ pub const Kill = struct {
 };
 
 pub const Dump = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         dump.dumpState(c.p) catch {};
     }
 };
 
 pub const Restore = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub fn run(c: Ctx) void {
         const path = c.arg orelse (c.p.last_dump orelse return);
@@ -256,6 +283,7 @@ pub const Restore = struct {
 };
 
 pub const Attach = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = pardes.can_attach;
     pub fn run(c: Ctx) void {
@@ -270,6 +298,7 @@ pub const Attach = struct {
 };
 
 pub const Detach = struct {
+    pub const scope: Scope = .session;
     pub const enabled = pardes.can_attach;
     pub fn run(c: Ctx) void {
         if (comptime enabled)
@@ -280,6 +309,7 @@ pub const Detach = struct {
 };
 
 pub const Mount = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = pardes.hosted;
     pub fn run(c: Ctx) void {
@@ -293,6 +323,7 @@ pub const Mount = struct {
 };
 
 pub const Unmount = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = pardes.hosted;
     pub fn run(c: Ctx) void {
@@ -318,12 +349,14 @@ pub const Msg = struct {
 };
 
 pub const NextColor = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         colors.setThemeIndex(c.p, (@as(usize, c.p.settings.theme) + 1) % pardes.themes.len);
     }
 };
 
 pub const ThemeSel = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.themes_buffer, .steps = true, .commands = true };
     pub fn run(c: Ctx) void {
         panes.Output.openThemes(c.p, c.id) catch |err| c.p.reportError(c.id, "themes", err);
@@ -331,6 +364,7 @@ pub const ThemeSel = struct {
 };
 
 pub const ThemeFile = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = pardes.hosted;
     pub fn run(c: Ctx) void {
@@ -342,6 +376,7 @@ pub const ThemeFile = struct {
 };
 
 pub const DumpThemes = struct {
+    pub const scope: Scope = .session;
     pub const enabled = pardes.hosted;
     pub fn run(c: Ctx) void {
         if (comptime enabled) {
@@ -355,6 +390,7 @@ pub const DumpThemes = struct {
 };
 
 pub const FontSel = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.fonts_buffer, .steps = true, .commands = true };
     pub const enabled = capabilities.font_picker;
     pub fn run(c: Ctx) void {
@@ -496,6 +532,7 @@ pub const New = struct {
 
 /// The same empty scratch, opened in a fresh column beside the calling pane.
 pub const Newcol = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         c.p.newScratchColumn(c.id);
     }
@@ -603,12 +640,14 @@ pub const Tty9p = struct {
 /// Fold the active pane's column into the one on its right, keeping its panes.
 /// The horizontal mirror of the vertical stacking `New` does.
 pub const Joincol = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         layout.joinCol(c.p);
     }
 };
 
 pub const Tutor = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         const free = c.p.freeSlot() orelse return;
         const nt = c.p.openTutorView(free) catch return;
@@ -617,6 +656,7 @@ pub const Tutor = struct {
 };
 
 pub const Help = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.help_buffer };
     pub fn run(c: Ctx) void {
         panes.Output.openHelp(c.p, c.id, "") catch |err| c.p.reportError(c.id, "help", err);
@@ -624,6 +664,7 @@ pub const Help = struct {
 };
 
 pub const Config = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.config_buffer };
     pub fn run(c: Ctx) void {
         panes.Output.openConfig(c.p, c.id) catch |err| c.p.reportError(c.id, "config", err);
@@ -631,6 +672,7 @@ pub const Config = struct {
 };
 
 pub const LocationsConfig = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const output: OutputTraits = .{ .name = "+LocationsConfig" };
 
@@ -660,6 +702,7 @@ pub const LocationsConfig = struct {
 };
 
 pub const Messages = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.messages_buffer };
     pub fn run(c: Ctx) void {
         panes.Output.openMessages(c.p, c.id) catch |err| c.p.reportError(c.id, "messages", err);
@@ -669,6 +712,7 @@ pub const Messages = struct {
 /// This build's version and what changed to reach it, printed into an output
 /// buffer the same way Config prints the live settings.
 pub const Changelog = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.changelog_buffer };
     pub fn run(c: Ctx) void {
         panes.Output.openChangelog(c.p, c.id) catch |err| c.p.reportError(c.id, "changelog", err);
@@ -676,6 +720,7 @@ pub const Changelog = struct {
 };
 
 pub const EffectCode = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = capabilities.panel_transitions or capabilities.scene_shaders;
     pub const output: OutputTraits = .{ .name = config.effect_code_buffer };
@@ -690,6 +735,7 @@ pub const EffectCode = struct {
 
 /// An optional SDL workspace-tag companion; never consumes input or text cells.
 pub const Pet = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = pardes.platform == .gui;
     pub fn run(c: Ctx) void {
@@ -793,6 +839,7 @@ pub const Right = struct {
 
 /// Ctrl-o: one step back into the history.
 pub const Back = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         c.p.jumpBy(-1);
     }
@@ -800,6 +847,7 @@ pub const Back = struct {
 
 /// Ctrl-i: one step forward again, up to wherever Back started.
 pub const Forward = struct {
+    pub const scope: Scope = .session;
     pub fn run(c: Ctx) void {
         c.p.jumpBy(1);
     }
@@ -821,6 +869,7 @@ pub const Last = struct {
 };
 
 pub const Jumplist = struct {
+    pub const scope: Scope = .session;
     pub const output: OutputTraits = .{ .name = config.jumps_buffer, .steps = true, .locations = true };
     pub fn run(c: Ctx) void {
         panes.Output.openJumps(c.p, c.id) catch |err| c.p.reportError(c.id, "jumplist", err);
@@ -920,6 +969,7 @@ pub const Lspwhy = struct {
 };
 
 pub const Peek = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = Board.enabled;
     pub const output: OutputTraits = .{ .name = config.peek_buffer };
@@ -932,6 +982,7 @@ pub const Peek = struct {
 };
 
 pub const Poke = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = Board.enabled;
     pub fn run(c: Ctx) void {
@@ -943,6 +994,7 @@ pub const Poke = struct {
 };
 
 pub const Hexdump = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = Board.enabled;
     pub const output: OutputTraits = .{ .name = config.hexdump_buffer };
@@ -955,6 +1007,7 @@ pub const Hexdump = struct {
 };
 
 pub const Gpio = struct {
+    pub const scope: Scope = .session;
     pub const takes_arg = true;
     pub const enabled = Board.enabled;
     pub const output: OutputTraits = .{ .name = config.gpio_buffer };