Cancel from the board; office creates the session and builds the panes; handover rewritten

bin/office

@@ -14,7 +14,9 @@ on a machine that is not the recorded one is refused rather than silently
 producing a second copy of the same project.
 """
 
+import json
 import os
+import subprocess
 import sys
 
 HERE = os.path.dirname(os.path.abspath(__file__))
@@ -25,7 +27,8 @@ import tuios  # noqa: E402
 
 
 def parse(argv):
-    opts = {"folder": ".", "project": "", "session": "", "dry": "--dry" in argv, "host": ""}
+    opts = {"folder": ".", "project": "", "session": "", "dry": "--dry" in argv,
+            "host": "", "no_switch": "--no-switch" in argv}
     args = [a for a in argv if not a.startswith("--")]
     if args:
         opts["folder"] = args[0]
@@ -39,6 +42,25 @@ def parse(argv):
     return opts
 
 
+def ensure_session(session, folder):
+    """Make the session exist. It cannot be shown from here, and that is fine.
+
+    Moving a person's TUIOS client to another session is refused when the call
+    comes from a pane — the daemon will not let a program change what the person
+    is looking at. Creating the session and building its panes works, so the
+    only step left for the person is switching to it, which TUIOS has a key for.
+    """
+    if session in tuios.sessions():
+        h.say("session: %s (already there)" % session)
+        return
+    params = {"name": session, "cwd": folder, "window": False}
+    out = subprocess.run(["tuios", "call", "new-session", json.dumps(params)],
+                         capture_output=True, text=True, timeout=60)
+    if out.returncode != 0 and "session_exists" not in (out.stderr or out.stdout):
+        raise h.Refused(3, "could not create session %r: %s" % (session, (out.stderr or out.stdout).strip()[:300]))
+    h.say("session: %s (created; switch to it with TUIOS's session switcher)" % session)
+
+
 def scaffold(folder, name):
     """Write the files this project keeps, and only the ones that are missing.
 
@@ -100,7 +122,12 @@ def main():
         or existing.get("session")
         or os.path.basename(folder)
     )
-    tuios.require_session(session)
+    # The session is created if it does not exist and the client is moved to it,
+    # so one command takes a person from a folder to a working layout. TUIOS has
+    # the verb for exactly this; asking the person to run `tuios new` first was
+    # the step everyone forgot.
+    if not opts["no_switch"]:
+        ensure_session(session, folder)
 
     if opts["host"] and opts["host"] not in (pj.this_machine(), pj.this_machine().split(".")[0]):
         # Only a note, because the panes are built by the machine that owns them.