Fix misleading extrapolation time in buffer_core (#832)

[selimrecep]

Description

This PR fixes the issue where extrapolation errors incorrectly prioritize metadata gathered during the initial source-to-root traversal (Phase 1). By comparing timestamps from both traversal phases, the error now correctly reports the 'latest data' time for the specific link on the requested transform path.

Verification

Reproduced with the script in #832:

• Before: Reported 10s staleness from unrelated 'map' frame.
• After: Reports 0.1s staleness for the actual 'odom -> base_link' path.

Fixes #832

[selimrecep]

IMHO TF2 error detection logic should be more path-aware in general, but I just wanted to focus on this specific bug for now.

[tfoote]

Thanks for adding this extra logic. Can you use the issue example to add a test case so that we can validate the error exists and that this fixes it and make sure that this doesn't regress at some point in the future.

The reproduction in the issues should provide most of what you need.

[selimrecep]

Done

[tfoote]

Thanks for the test too. It looks good to me now.

[ahcorde]

Pulls: #896
Gist: https://gist.githubusercontent.com/ahcorde/ccf434b60715e64e4abc3e29fe357122/raw/a1dd8e171ed2aa8958932f14ef5aedf09453b878/ros2.repos
BUILD args: --packages-above-and-dependencies tf2
TEST args: --packages-above tf2
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/18540

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[ahcorde]

https://github.com/Mergifyio backport kilted jazzy humble

[mergify]

backport kilted jazzy humble

✅ Backports have been created

Details

• #897 Fix misleading extrapolation time in buffer_core (#832) (backport #896) has been created for branch kilted
• #898 Fix misleading extrapolation time in buffer_core (#832) (backport #896) has been created for branch jazzy
• #899 Fix misleading extrapolation time in buffer_core (#832) (backport #896) has been created for branch humble