docs+test+ergonomics(cli): address Copilot review on #1086 export

Three corrections from @copilot-pull-request-reviewer:

1. **Top-of-module docstring updated.** The "Commands" list and
   "Examples" block now mention `mempalace export -o <dir>` so
   `mempalace --help` documents the new subcommand consistently
   with the rest. The epilog is built from this docstring via
   __doc__, so a stale list is what users actually see.

2. **Per-subcommand --palace dropped.** Other subcommands
   (mine/search/mcp/status/wake-up) all read args.palace from
   the global root-parser flag; export's local duplicate broke
   that consistency. Replaced with a comment explaining the
   choice. Usage is now `mempalace --palace <p> export -o <d>`.
   (cmd_export already accesses args.palace, which still resolves
   correctly via the global parser.)

3. **test_main_export_dispatches added.** Mirrors the
   test_main_<cmd>_dispatches pattern used for every other
   subcommand. Asserts the argparse wiring delivers both the
   global --palace and the -o/--output to cmd_export, and locks
   in that --output (long form) is also accepted.

45/45 tests pass in tests/test_cli.py.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jphein

mempalace/cli.py

@@ -16,6 +16,7 @@
     mempalace mine <dir> --mode convos    Mine conversation exports
     mempalace mine <dir> --mode extract   Mine binary office documents (PDF/DOCX/etc.)
     mempalace search "query"              Find anything, exact words
+    mempalace export -o <dir>             Export the palace as browsable markdown (one file per room)
     mempalace mcp                         Show MCP setup command
     mempalace wake-up                     Show L0 + L1 wake-up context
     mempalace wake-up --wing my_app       Wake-up for a specific project
@@ -27,6 +28,7 @@
     mempalace mine ~/.claude/projects/-Users-you-Projects-my_app --mode convos --wing my_app
     mempalace search "why did we switch to GraphQL"
     mempalace search "pricing discussion" --wing my_app --room costs
+    mempalace export -o ~/Desktop/palace-export
 """
 
 import os
@@ -1784,7 +1786,10 @@ def main():
     p_export.add_argument(
         "-o", "--output", required=True, help="Output directory for markdown files"
     )
-    p_export.add_argument("--palace", help="Path to palace directory (default: from config)")
+    # No per-subcommand --palace: rely on the root parser's global --palace
+    # so usage is `mempalace --palace <path> export -o <dir>` — consistent
+    # with mine / search / mcp / status / wake-up which all read args.palace
+    # from the global flag.
 
     args = parser.parse_args()
     _apply_backend_arg(args)

tests/test_cli.py

@@ -823,6 +823,36 @@ def test_main_split_dispatches():
         mock_cmd.assert_called_once()
 
 
+def test_main_export_dispatches():
+    """Argparse wiring + main() dispatch for the export subcommand.
+
+    Locks in -o/--output as the required arg and that the global
+    --palace flag (root parser) reaches cmd_export via args.palace
+    — there is no per-subcommand --palace.
+    """
+    from mempalace.cli import cmd_export  # noqa: F401 — sanity import
+
+    with (
+        patch("sys.argv", ["mempalace", "--palace", "/tmp/p", "export", "-o", "/tmp/out"]),
+        patch("mempalace.cli.cmd_export") as mock_cmd,
+    ):
+        main()
+        mock_cmd.assert_called_once()
+        # Forwarded args carry both the global --palace and -o/--output.
+        forwarded = mock_cmd.call_args[0][0]
+        assert forwarded.palace == "/tmp/p"
+        assert forwarded.output == "/tmp/out"
+
+    # And the long form -o == --output.
+    with (
+        patch("sys.argv", ["mempalace", "export", "--output", "/tmp/out2"]),
+        patch("mempalace.cli.cmd_export") as mock_cmd,
+    ):
+        main()
+        mock_cmd.assert_called_once()
+        assert mock_cmd.call_args[0][0].output == "/tmp/out2"
+
+
 def test_mcp_command_prints_setup_guidance(monkeypatch, capsys):
     monkeypatch.setattr(sys, "argv", ["mempalace", "mcp"])