Two review findings on 32821c6.
1. Once the shielded rollback body runs after a real client cancellation it
can fail (the COM hard timeout, _safe_send_command's own deadline, an
ezdxf quarantine refusal). That RuntimeError escaped run_spec as an
ordinary error and the mcp lowlevel server, which had already answered
the cancelled request, tried to respond a second time: `assert not
self._completed` in mcp/shared/session.py escaped the server task group
and the whole session died (measured through the real transport: the next
system_status was never answered and Client.__aexit__ re-raised the
AssertionError). run_spec now decides by the exception it is handling:
after a cancellation the rollback error is logged and the cancellation is
what propagates, so the SDK's cancellation suppression applies; after any
other error the rollback error propagates as before, with the original
chained as its context.
2. The docstring promised the rollback on both engines, but on the live
AutoCAD 2026 ComBackend.transaction_rollback sent `_UNDO B` with no UNDO
Mark in the stack (StartUndoMark/EndUndoMark form an undo *group*, not a
Mark), AutoCAD answered "This will undo everything. OK? <Y>", SendCommand
blocked at that prompt, _run gave up after 60 s, the entities stayed and
every COM client was rejected until a human pressed ESC. transaction_begin
now types `_.UNDO _M` before StartUndoMark (refused with ok:false while
CMDACTIVE, where the Mark would be swallowed as input), and
transaction_rollback ends the group and sends `_.UNDO _B`, which returns
exactly to that Mark - also on an empty transaction, where `_UNDO 1` would
be one step too many. A rollback with no transaction is refused the way the
headless engine refuses it, because an unmarked Back is that prompt.
Measured with the real ComBackend in a scratch Documents.Add() document on
the running AutoCAD 2026 (closed with Close(False)): begin 31 ms ->
entity_create_line + circle -> rollback 63 ms -> 3 entities back to 1,
CMDACTIVE 0, no prompt; an empty begin/rollback leaves the older line;
begin/commit unchanged.
Tests: the two failure modes on run_spec (anyio scope cancellation with a
raising rollback completes the task group and logs; a ValueError with a
raising rollback still raises the rollback error with the ValueError as
context), the real-transport case (client.cancel mid-run, rollback raises,
the next request is answered, cleanup through the real rollback), the COM
shape now pins `_.UNDO _M, StartUndoMark, EndUndoMark, _.UNDO _B`, and
test_com_sprint3 grows a Mark-keeping fake document whose unmarked Back
fails the way the prompt does: begin before the group, rollback consumes the
Mark, rollback without a transaction sends nothing, begin refuses on
CMDACTIVE.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
ruff format was never run repo-wide; CI now enforces 'ruff format --check', so normalize every module once. No behavior changes.
Co-authored-by: Cursor <cursoragent@cursor.com>
Audit-driven fixes across the dual backend, the premium workflow, and the
engineering layer. 318 tests, ruff-clean.
Quality gate (the moat):
- drawing_finalize now runs the premium ISO-128 critique in addition to the
8-step validator; leftover construction, non-ISO lineweights, untrimmed
corners, duplicates and dim overlap block the gate (strict_critique fails on
warnings too).
- dim_overlap critique no longer a no-op (dim reference point + bbox fallback);
dim/construction layers resolve from the active layer set (iso13567 too).
Stability / correctness:
- view_screenshot & drawing_export_pdf render headless via Agg (no more
worker-thread SIGSEGV).
- gear tooth profile no longer self-overlaps at high tooth counts; section view
no longer duplicates bore lines; validator keyway heuristic fixed.
- ezdxf aligned/angular dim API, full-circle polar array duplicate already
covered by Sprint 1; this bundle adds save-format-from-extension,
entity_offset side selection, ARC length, properties parity (bounding_box /
rotation / char_height), mtext rotation.
COM robustness (mocked-COM tested):
- CoUninitialize on teardown; transaction commit/rollback try/finally + UNDO via
the CMDACTIVE guard; system_run_lisp guard + USERS1 value capture;
set_variable type coercion; HWND via Application.HWND; BlockInfo.description.
Security:
- HTTP remote-bind guard fires on every launch path (incl. `fastmcp run`);
StaticTokenVerifier wired into FastMCP; AutoLISP allowlist bypass-vector tests.
Hygiene: linetype-on-demand in _apply_attrs, honest view_zoom returns, snap-on-arc
sweep handling, point_tangent acos clamp, dynamic tool_groups / tool count,
word-boundary SPUR/HELICAL, undo-stack locking.
Deferred: R22 (undo/transaction stack isolation) lands with the I1 refiner (1.2),
which depends on it.
