fix: 按复位请求目标确认参考版本并隔离复位状态

防止在途旧帧提前触发归零，并保留旧 reset 用法。SDK 101 项针对性回归与 lint 通过。

docs/sensor-bundles.md

@@ -165,6 +165,16 @@ compute the same numbers.
 ## Resetting the reference
 
 Both backends process externally supplied frames through the same profile. After a gap in the
-input - a pause, a seek, a scene change - call `session.reset()`. It is queued to the stage that
-owns the tracker, so the reference frame is rebased on the frame about to be computed rather than
-on a buffer the pipeline is still reading.
+input - a pause, a seek, a scene change - call `session.reset()`. It is queued to the stages that
+own the sensor state, so the reference frame is rebased on the frame about to be computed rather
+than on a buffer the pipeline is still reading: the flow stage resets the image/tracker state and
+bumps the reference version, and the HHD stage resets the force/readout state (filters, contact
+flags, calibration session) on the first frame carrying the new version, before decomposing it.
+`FrameSnapshot.tracker_reset_seq` is the version that frame was measured with.
+
+When driving `StreamPipeline` directly, call `target = pipeline.request_reset()` to obtain the
+future reference version reserved by that request. Confirm it only when a snapshot carries
+`tracker_reset_seq >= target`; the current output frame can trail an earlier reset and cannot
+identify a new request. Requests share a target until flow claims it; a later request gets a new
+target even while the earlier reset is still being applied. The existing `reset()` returns `None`.
+Regression coverage lives in `tests/test_pipeline.py` (request coalescing and reset-in-progress).