Add the abandon command

A4 already names abandon as one of the ways out of a halt (continue,
re-plan, or abandon) and 0.2 closes a work item as completed or
abandoned, but no command did it: from a gate or a question the only way
to drop a task was to edit the state database.

- 'abandon' ends the task from any waiting state and returns to IDLE.
  The move is made durable first; then the plan issue and any open
  milestone PR are closed with a note (branches kept), and any
  unresolved intent is aborted so boot reconciliation does not gate on
  work dropped on purpose. A Gitea failure is reported, not fatal.
- Like 'status' it is a command in every state, never read as an answer
  or feedback. While work runs, 'stop' comes first, as before.
- The restart / stranded question and the PR_OPEN hints mention it.
- Spec: B1 gains the abandon edge and B2 the command.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/src/nisse_dev/control.py

@@ -55,6 +55,10 @@ TRANSITIONS = {
     # than passing through a separate FINISHED state.
     (PR_OPEN, MILESTONE_PLANNING),
     (PR_OPEN, IDLE),
+    # abandon (A4, B2): the operator may end the task from any waiting state.
+    # (AWAIT_INPUT may go anywhere already.)
+    (AWAIT_ARCH_SIGNOFF, IDLE),
+    (AWAIT_MILESTONE_SIGNOFF, IDLE),
 }
 
 
@@ -65,7 +69,7 @@ _WORKING = (PLANNING_ARCH, MILESTONE_PLANNING, EXECUTING)
 
 _BOOT_CHOICES = (
     "reply 'continue' to pick up where the restart cut in, "
-    "or 're-plan' to plan the current step again"
+    "'re-plan' to plan the current step again, or 'abandon' to drop the task"
 )
 
 
@@ -117,6 +121,8 @@ class MilestonePublisher(Protocol):
 
     def comment(self, index: int, body: str) -> None: ...
 
+    def close_pull_request(self, index: int, note: str) -> None: ...
+
 
 class PlanBoard(Protocol):
     """The Gitea side of plan gating; the concrete one is in
@@ -128,6 +134,8 @@ class PlanBoard(Protocol):
 
     def echo(self, issue: int, text: str) -> None: ...
 
+    def close(self, issue: int, note: str) -> None: ...
+
 
 class PlanningAgent(Protocol):
     def plan(
@@ -428,6 +436,13 @@ class Orchestrator:
         text = msg.text.strip()
         if text == "status":
             self._send_status(current)
+        elif text == "abandon":
+            # Like status, a command in every waiting state: it takes
+            # precedence over reading the word as an answer or feedback.
+            if current == IDLE:
+                self._transport.send_message("no active task; nothing to abandon")
+            else:
+                self._abandon(msg.sender)
         elif current == IDLE:
             if text.startswith("use "):
                 self._begin_project(text[4:].strip())
@@ -821,7 +836,7 @@ class Orchestrator:
             self._transition(PR_OPEN, cause=f"[stub] milestone {milestone} done")
             self._transport.send_message(
                 f"[stub] milestone {milestone} done; no publisher, so no PR — "
-                "say 'next milestone' or 'project complete'"
+                "say 'next milestone', 'project complete' or 'abandon'"
             )
             return
         gate = self._data.get("gate") or {}
@@ -869,13 +884,49 @@ class Orchestrator:
             "'project complete'"
         )
 
+    def _abandon(self, sender: str) -> None:
+        """End the task on the operator's word (A4: continue, re-plan, or
+        abandon), closing its Gitea records. Only reached from a waiting
+        state: while work runs the reply is "busy; say 'stop'" instead.
+
+        The move to IDLE is made durable first, so a failure while tidying
+        Gitea can never leave a live task behind a closed plan issue."""
+        note = f"abandoned by {sender}"
+        board_state = self._data.get("board") or {}
+        pr = self._data.get("pr") or {}
+        project = self._project
+        self.stop_watching()
+        self._data = {**_fresh_data()}
+        self._project = None
+        self._store.oplog.task_id = None
+        self._transition(IDLE, cause=f"operator: abandon ({sender})")
+
+        # Dropped on purpose: boot reconciliation must not gate on it.
+        for intent in self._store.pending_intents():
+            self._store.abort_intent(intent.id, cause=note)
+        problems: list[str] = []
+        if self._board is not None and board_state.get("issue"):
+            try:
+                self._board.close(int(board_state["issue"]), note)
+            except GiteaError as exc:
+                problems.append(f"plan issue #{board_state['issue']}: {exc}")
+        if self._publisher is not None and pr.get("number"):
+            try:
+                self._publisher.close_pull_request(int(pr["number"]), note)
+            except GiteaError as exc:
+                problems.append(f"PR #{pr['number']}: {exc}")
+        closed = "; could not close " + ", ".join(problems) if problems else ""
+        self._transport.send_message(
+            f"task on {project} abandoned{closed}. Say 'use <project>' to start another"
+        )
+
     def _return_to_pr_open(self, cause: str) -> None:
         self._transition(PR_OPEN, cause=cause)
         pr = self._data.get("pr") or {}
         self._watch_pr(pr)
         self._transport.send_message(
             f"PR #{pr.get('number')} is open and watched for review comments; "
-            "say 'next milestone' or 'project complete'"
+            "say 'next milestone', 'project complete' or 'abandon'"
         )
 
     def _watch_pr(self, pr: dict[str, Any]) -> None:
@@ -909,8 +960,8 @@ class Orchestrator:
         else:
             pr = self._data.get("pr") or {}
             self._transport.send_message(
-                f"PR #{pr.get('number')} is open; say 'next milestone' or "
-                "'project complete'"
+                f"PR #{pr.get('number')} is open; say 'next milestone', "
+                "'project complete' or 'abandon'"
             )
 
     def _watch(