bench: matrix v4 adds page_setup_truth; correctness suite grows to 32 with three settings checks (A/B vs v1.5.1: 26 -> 32 / 32)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

benchmarks/tasks_v4.py

@@ -1,10 +1,16 @@
-"""The v4 task matrix: v3 plus the P&ID round trip (v1.6, track A).
+"""The v4 task matrix: v3 plus what 1.6 added.
 
-``pid_roundtrip`` draws a five-item P&ID through the same code the tools call
-and reads it back: the edge count, the absence of dangling ends and the
-instrument index are each derived independently of the drawing code. The
-published competitor reports were never asked this question; the chart shows
-``not_run`` for them, not zero.
+``pid_roundtrip`` (track A) draws a five-item P&ID through the same code the
+tools call and reads it back: the edge count, the absence of dangling ends
+and the instrument index are each derived independently of the drawing code.
+
+``page_setup_truth`` (track E) applies an ISO A3 landscape page setup to a
+layout, plots it through ``batch_plot`` and reads the sheet size back from
+the PDF's own ``/MediaBox`` — the setup is verified by the file, not by the
+setter's return value.
+
+The published competitor reports were never asked either question; the chart
+shows ``not_run`` for them, not zero.
 """
 
 from __future__ import annotations
@@ -12,7 +18,7 @@ from __future__ import annotations
 from benchmarks.tasks_v2 import TASKS_V2, TaskSpec
 from benchmarks.tasks_v3 import TASKS_V3
 
-#: Added in v1.6.0. The reader can fail this one on its own.
+#: Added in v1.6.0. Each can fail on its own.
 NEW_TASKS_V4: tuple[TaskSpec, ...] = (
     TaskSpec(
         "pid_roundtrip",
@@ -20,6 +26,12 @@ NEW_TASKS_V4: tuple[TaskSpec, ...] = (
         "Draw a P&ID from a spec and read back a matching graph, index and line list",
         1.0,
     ),
+    TaskSpec(
+        "page_setup_truth",
+        "pagesetup",
+        "Apply an ISO A3 page setup, plot it, and read the sheet size back from the PDF",
+        1.0,
+    ),
 )
 
 TASKS_V4: tuple[TaskSpec, ...] = TASKS_V3 + NEW_TASKS_V4