[PierreRaybaut]

The instrument window recomputed its axes only when the X axis changed (size or bounds of the signals), so a new InstrumentFrame.value_range with the same time base was ignored. In the oscilloscope simulator, changing a channel scale or offset left the Y axis on the previous setting.

Now, when only the value range changes, the Y axis follows it (or is autoscaled alone when the range becomes None), and the user's zoom along X is kept, as when changing V/div on a real oscilloscope. A change of the X axis still rescales both axes.

Tests

• plugin_tools_app_test.py now zooms along X, then renders a frame with the same X and a new range: Y follows and the X zoom is kept; without a range, Y is autoscaled alone; a new X axis is rescaled. This test fails on the previous code (Y stayed at (-2, 2) instead of (-5, 5)).
• Plugin feature and backbone tests: 196 passed (the 3 plugin_generator_unit_test.py failures are environmental: sigimax missing in a subprocess).

DataLab-Web is not affected: a browser probe on the unchanged code showed that, after a user zoom, the Y axis follows a new value range and the X zoom is kept.

Assisted-by: Claude Opus 5.5