feat(cli): help, and right-click copy and paste in the interactive chat

help prints what --help prints; help ACTION, what ACTION --help prints.

In the interactive chat a right-click on the conversation copies the text
selected with the mouse, else the line under the pointer: to the terminal
(OSC 52) and to the platform's clipboard tool. A right-click on the line
written in pastes the system clipboard's text at the cursor, its lines side
by side, read with wl-paste, xclip or xsel, pbpaste or PowerShell, else what
was copied here last. The conversation is selectable with the mouse, which
RichLog alone is not. The deb and rpm packages recommend wl-clipboard or
xclip for the paste.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/packages/meshbay-cli/src/meshbay_cli/commands/help.py b/packages/meshbay-cli/src/meshbay_cli/commands/help.py
new file mode 100644
index 0000000..6515800
--- /dev/null
+++ b/packages/meshbay-cli/src/meshbay_cli/commands/help.py
@@ -0,0 +1,27 @@
+"""`help`: what `--help` prints, for the program or for one action."""
+
+from ..errors import USAGE, CliError
+from ..output import sentence
+from .context import Context
+
+HELP = "what --help prints: the actions, or one action's options"
+
+
+def add_parser(sub, parent) -> None:
+    p = sub.add_parser("help", parents=[parent], help=HELP, description=sentence(HELP) + ".")
+    p.add_argument("topic", nargs="?", metavar="ACTION", help="the action to explain")
+
+
+async def run(ctx: Context) -> int:
+    from ..__main__ import build_parser
+    parser = build_parser()
+    topic = ctx.args.topic
+    if topic is None:
+        parser.print_help()
+        return 0
+    actions = next(a for a in parser._actions if hasattr(a, "choices") and a.choices
+                   and "help" in a.choices).choices
+    if topic not in actions:
+        raise CliError(USAGE, f"No action {topic!r}. The actions: {', '.join(actions)}.")
+    actions[topic].print_help()
+    return 0