mcp(api[pane_tools]): drop respawn-pane resolver fallbacks

Trim respawn_pane's signature to the parameters it actually honors.
The session_name / session_id / window_id fields existed only to mirror
sibling pane tools' shared resolver shape, but the in-tool guard raised
ToolError on any combination missing pane_id — so they were dead surface
area broadcasting targeting flexibility to LLMs that did not exist.

Validation now lives at the FastMCP schema boundary (pane_id: str, no
default) instead of an in-tool ToolError raise. The two tests that
exercised the runtime guard are deleted; one became a Python TypeError
on the trimmed signature, the other passed a parameter that no longer
exists. The remaining respawn_pane tests are unchanged — they all
called with explicit pane_id from the start.

Settled before respawn-pane reaches origin/main so no compat alias
ships.

Author: tony

CHANGES

@@ -107,6 +107,16 @@ _Notes on upcoming releases will be added here_
   branch. Settled before the tool reached ``origin/main`` so no
   compatibility alias is shipped — alignment is the load-bearing
   reason, not a fix to a previously released name.
+- {tooliconl}`respawn-pane` signature drops the optional
+  ``session_name`` / ``session_id`` / ``window_id`` resolver fallbacks
+  that sibling pane tools accept. The runtime guard would have raised
+  on any combination missing ``pane_id`` anyway (the tool requires
+  explicit ``pane_id`` to prevent silent-kill-via-resolver), so the
+  parameters were dead surface area broadcasting targeting flexibility
+  to LLMs that did not exist. Validation now lives at the FastMCP
+  schema boundary via ``pane_id: str`` rather than an in-tool
+  ``ToolError`` raise. Settled before the tool reached ``origin/main``
+  so no compat alias ships.
 
 ### Refactor
 

src/libtmux_mcp/tools/pane_tools/lifecycle.py

@@ -60,10 +60,7 @@ def kill_pane(
 
 @handle_tool_errors
 def respawn_pane(
-    pane_id: str | None = None,
-    session_name: str | None = None,
-    session_id: str | None = None,
-    window_id: str | None = None,
+    pane_id: str,
     kill: bool = True,
     shell: str | None = None,
     start_directory: str | None = None,
@@ -84,11 +81,13 @@ def respawn_pane(
     variables for the relaunched command (one ``-e KEY=VALUE`` flag
     per entry).
 
-    ``pane_id`` is required — no fallback to ``_resolve_pane``'s
-    "first pane in session/window" behaviour. Default ``kill=True``
-    will terminate the resolved pane's process, so accidental targeting
-    can silently kill an unrelated server. Resolve via ``list_panes``
-    first.
+    ``pane_id`` is required — sibling pane tools accept a hierarchical
+    fallback (``session_name`` / ``window_id`` / ``pane_index``) that
+    resolves to "first pane in session/window", but combined with
+    default ``kill=True`` that fallback could silently kill an
+    unrelated process. The signature deliberately omits the resolver
+    fields so the FastMCP schema rejects them at the framework
+    boundary. Resolve via ``list_panes`` first.
 
     Tip: call ``get_pane_info`` first if you need to capture
     ``pane_current_command`` before respawn — the new process loses its
@@ -99,15 +98,7 @@ def respawn_pane(
     Parameters
     ----------
     pane_id : str
-        Pane ID (e.g. '%1'). Required — no fallback resolution.
-    session_name : str, optional
-        Accepted for backwards-compatibility with the ``_resolve_pane``
-        signature shared across pane tools, but the explicit ``pane_id``
-        guard above raises before this is consulted.
-    session_id : str, optional
-        See ``session_name``.
-    window_id : str, optional
-        See ``session_name``.
+        Pane ID (e.g. '%1'). Required.
     kill : bool
         When True (default), pass ``-k`` to tmux so the current
         process is killed before respawning. When False, respawn
@@ -140,21 +131,8 @@ def respawn_pane(
         Serialized pane metadata after respawn. The pane_id is
         preserved; pane_pid reflects the new process.
     """
-    if pane_id is None:
-        msg = (
-            "respawn_pane requires an explicit pane_id (e.g. '%1') because "
-            "default kill=True will terminate the resolved pane's process. "
-            "Resolve the target via list_panes first."
-        )
-        raise ToolError(msg)
     server = _get_server(socket_name=socket_name)
-    pane = _resolve_pane(
-        server,
-        pane_id=pane_id,
-        session_name=session_name,
-        session_id=session_id,
-        window_id=window_id,
-    )
+    pane = _resolve_pane(server, pane_id=pane_id)
     caller = _get_caller_identity()
     if (
         caller is not None

tests/test_pane_tools.py

@@ -312,38 +312,6 @@ def test_respawn_pane_self_kill_guard(
     new_pane.kill()
 
 
-def test_respawn_pane_rejects_implicit_target(mcp_server: Server) -> None:
-    """respawn_pane refuses when no targeting parameter is supplied.
-
-    Without ``pane_id`` (or any other discriminator) ``_resolve_pane``
-    falls back to the first pane of the first window of the first
-    session — combined with default ``kill=True`` that could silently
-    kill an unrelated server. The runtime guard requires explicit
-    ``pane_id``.
-    """
-    with pytest.raises(ToolError, match="explicit pane_id"):
-        respawn_pane(socket_name=mcp_server.socket_name)
-
-
-def test_respawn_pane_rejects_session_only_target(
-    mcp_server: Server, mcp_session: Session
-) -> None:
-    """respawn_pane refuses ``session_name`` without ``pane_id``.
-
-    ``session_name`` alone resolves to the first pane of the first
-    window, which is not what the caller intends when recovering a
-    wedged shell elsewhere in the session. The guard requires
-    ``pane_id`` regardless of which other targeting parameters are
-    present.
-    """
-    assert mcp_session.session_name is not None
-    with pytest.raises(ToolError, match="explicit pane_id"):
-        respawn_pane(
-            session_name=mcp_session.session_name,
-            socket_name=mcp_server.socket_name,
-        )
-
-
 def test_respawn_pane_kill_false_on_dead_pane_succeeds(
     mcp_server: Server, mcp_session: Session
 ) -> None: