KiCAD nightly builds occasionally return a SwigPyObject from
pcbnew.LoadBoard, and SaveBoard can leave self.board with no method
dispatch as a side-effect of certain sequences (delete_trace + auto-save
is the one users have hit in the wild). Before this fix, open_project
would keep reporting "Opened project: foo.kicad_pcb" while every
subsequent board operation failed with AttributeError on
GetDesignSettings / GetBoardEdgesBoundingBox / GetCurrentViaSize, with
no path to recovery short of restarting the MCP server.
Add two helpers in KiCADInterface:
* _is_board_healthy(board=None) probes for stable BOARD methods
(GetDesignSettings, GetBoardEdgesBoundingBox, GetFileName) — these
are missing on a dehydrated SwigPyObject, so hasattr() catches the
state without segfaulting.
* _safe_load_board(path) wraps pcbnew.LoadBoard, checks health, and
on dehydration reloads the pcbnew module via importlib.reload and
retries once. Returns None when recovery is impossible so callers
surface real failure rather than fake success.
Wire the helpers in:
* handle_command's open_project / create_project path validates the
loaded board and either recovers (with a warnings[] entry) or
returns success=False with an explicit "restart the MCP server"
errorDetails — never claims success when the board is unusable.
* _auto_save_board now detects dehydration introduced by SaveBoard
itself and reloads from disk so the next command sees a usable
proxy. This is the post-delete_trace failure mode users hit.
* _handle_place_component, _handle_sync_schematic_to_board,
_handle_import_svg_logo and _handle_refill_zones all go through
_safe_load_board instead of bare LoadBoard, surfacing real errors
consistently.
Also fix two adjacent issues observed in the same incident:
* _handle_check_kicad_ui used to call manager.is_running() and
manager.get_process_info() separately, with different detection
methods. They could disagree, producing the confusing
running=True, processes=[] state users hit after manually
quitting KiCAD. processes is now the single source of truth and
running is derived from len().
* run_drc accepts a timeoutSec param (default 600s, clamped to
[10, 1800]) so callers with smaller MCP transport budgets can
bound the kicad-cli subprocess. Same timeout is applied to the
optional report-generation subprocess. Error message names the
actual timeout that fired.
Tests: tests/test_swig_dehydration.py adds 17 unit tests covering
detection, recovery, the open_project surfacing path, the auto-save
post-recovery path, the check_kicad_ui consistency, and the run_drc
timeout clamping. Full suite: same 12 pre-existing failures both
before and after this change, +17 new tests passing.
Note: the SWIG dehydration is fundamentally a pcbnew memory bug
exposed by repeated LoadBoard calls in a single Python process;
this PR is a defensive recovery layer, not a fix to the underlying
binding. Complementary to PR #151 (auto-save-guard), which expands
the LoadBoard call rate by refusing saves on external file change
and forcing re-open_project cycles.
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