Plan 9 idiom for the control filesystem, and the regressions a624a56 left

The 9P tree stops being a command language wearing a filesystem. /new
created a pane as a side effect of a *read*; it is now Tcreate in /pane,
with Tremove to close, which cloud9's engine has always supported and the
editor never declared: tree.zig now says
`features = .{ .create = true, .remove = true }`. Eleven pane ctl verbs
become files that can be read as well as written -- dot, limit, dirty,
mark, scroll, look, exec -- leaving ctl with `get`, the one verb no file
would say better. Root /ctl splits into a read-only /status and the
/look and /exec files whose write IS the click. stat carries real sizes
where it used to answer 0, and qid versions track a pane's revision, so a
client can poll for change without re-reading the body.

Commit a624a56 moved raw-tty keys to an early-return branch that knew only
Ctrl-B and bare Escape, and in the same edit deleted the paste branch below
it. That cost Shift-Escape (the unconditional way out of tty mode) and both
paste chords: Ctrl-V and Ctrl-Shift-V reached the child as keystrokes, so an
agent CLI running in a pane took Ctrl-V for its image-paste binding and
answered "No image found in clipboard". Both are restored, with tests.

Nested detection was not subtly broken but deleted: 60367d8 removed
nested.zig's process-ancestry walk and left "am I inside pardes" derived from
PARDES_FORWARD_LOOK, which read "0" both for --nested and for "the listener
did not come up". PARDES_PID now answers that question on its own, checked
with kill(pid, 0); PARDES_9P and PARDES_PANE answer how to reach it; the flag
is gone. The posted-9P registry also self-heals now -- a session that aborts
cannot unlink its own socket, so posting sweeps entries whose target refuses
a connection, symlinks only and on a definite ECONNREFUSED only.

Elsewhere: tty scrolling is sticky-bottom, following new output only from
the last row, with typing and entering raw mode snapping back to live; the
boot layouts are a Boot enum instead of a chain of ifs, and the bare tty
startup (Boot.tty, which main.zig names) opens an empty text pane under the
shell while tests keep Boot.tty_shell; builtins announce themselves on the
message row under a Verbose setting that is on by default; Config prints
each setting the way you would type it back, so WindowOpacity 70 rather than
"WindowOpacity: 70%"; LocationsConfig opens its window only when called bare;
every tagline puts the word that closes the thing last, and a column now
outlives its panes -- closing the last one leaves an empty pane, and only
Delcol, newly on the column tagline, takes the column away.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

1 files changed, 16 insertions, 16 deletions

diff --git a/test/output.zig b/test/output.zig
index 07a1ce23..1fcb6104 100644
--- a/test/output.zig
+++ b/test/output.zig
@@ -543,10 +543,10 @@ test "Config prints the startup path and refreshes its one output" {
     const out = p.panes[opened].?.file.?;
     for ([_][]const u8{
         "Startup config: " ++ path ++ "\n",
-        "Theme: orchard\n",
-        "Shell requested (new panes): " ++ config.default_shell ++ " (default)\n",
-        "Shell effective (last spawn): (none)\n",
-        "Shell pending: on\n",
+        "Theme orchard\n",
+        "Shell requested (new panes) " ++ config.default_shell ++ " (default)\n",
+        "Shell effective (last spawn) (none)\n",
+        "Shell pending on\n",
     }) |line| try std.testing.expect(std.mem.indexOf(u8, out.content, line) != null);
     try std.testing.expectEqualStrings(config.config_buffer, std.fs.path.basename(out.path));
     try std.testing.expectEqual(panes.Output.Origin{ .cmd = .Config }, out.output.?.from);
@@ -653,36 +653,36 @@ test "every enabled setting builtin mutates the State Config reports" {
     try std.testing.expect(p.executeBuiltinLine(p.active, "Config"));
     const report = p.panes[p.active].?.file.?.content;
     for ([_][]const u8{
-        "Colors: off\n",
-        "Wrap: off\n",
-        "Tagbottom: on\n",
-        "Debug: on\n",
-        "Theme: acme\n",
-        "Shell requested (new panes): fish\n",
+        "Colors off\n",
+        "Wrap off\n",
+        "Tagbottom on\n",
+        "Debug on\n",
+        "Theme acme\n",
+        "Shell requested (new panes) fish\n",
     }) |line| try std.testing.expect(std.mem.indexOf(u8, report, line) != null);
     const transition = if (builtins.capabilities.panel_transitions)
-        try std.fmt.bufPrint(&buf, "Panel transition: {s}\n", .{
+        try std.fmt.bufPrint(&buf, "Panel transition {s}\n", .{
             config.Runtime.findAction(.{ .transition = p.settings.panel_transition }).?.word,
         })
     else
-        "Panel transition: unsupported\n";
+        "Panel transition unsupported\n";
     try std.testing.expect(std.mem.indexOf(u8, report, transition) != null);
     const scene_status = if (builtins.capabilities.scene_shaders) "on" else "unsupported";
     for ([_][]const u8{ "Crt", "Ripple", "Glitch" }) |name| {
-        const line = try std.fmt.bufPrint(&buf, "{s}: {s}\n", .{ name, scene_status });
+        const line = try std.fmt.bufPrint(&buf, "{s} {s}\n", .{ name, scene_status });
         try std.testing.expect(std.mem.indexOf(u8, report, line) != null);
     }
     const tagline = if (!builtins.capabilities.tagline_font_size)
-        "TaglineSize: unsupported\n"
+        "TaglineSize unsupported\n"
     else
-        try std.fmt.bufPrint(&buf, "TaglineSize: {d}%{s}\n", .{
+        try std.fmt.bufPrint(&buf, "TaglineSize {d}{s}\n", .{
             p.settings.font.tagline_percent,
             if (builtins.capabilities.font_picker) "" else " (build-time only)",
         });
     try std.testing.expect(std.mem.indexOf(u8, report, tagline) != null);
     if (chosen_font) |name| {
         try std.testing.expect(std.mem.indexOf(u8, report, name) != null);
-        try std.testing.expect(std.mem.indexOf(u8, report, "Font pending: on\n") != null);
+        try std.testing.expect(std.mem.indexOf(u8, report, "Font pending on\n") != null);
     }
 }