[16.1.X] Adjust TICL v4 track linking to work with (extended) pixel tracks

[mmusich]

PR description:

As it has become clear in the meanwhile that in this release cycle the default TICL reconstruction will remain v4 (This PR enabling TICL v5 targets the cycle 17.0.X), I forward-port part of commit fa4b170 (from PR #50179) to allow efficient track linking in TICLv4 with extended pixel tracks in 16.1.X.

PR validation:

See description in PR #50031

If this PR is a backport please specify the original PR and why you need to backport that PR. If this PR will be backported please specify to which release cycle the backport is meant for:

Partial forward port of #50179 to CMSSW_16_1_X.

[mmusich]

type ngt

[cmsbuild]

A new Pull Request was created by @mmusich for CMSSW_16_1_X.

It involves the following packages:

• RecoHGCal/TICL (reconstruction)

@Moanwar, @cmsbuild, @jfernan2, @mandrenguyen, @srimanob can you please review it and eventually sign? Thanks.
@apsallid, @denizsun, @felicepantaleo, @forthommel, @hatakeyamak, @lecriste, @rovere, @salimcerci, @sameasy, @sobhatta this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

[cmsbuild]

cms-bot internal usage

[mmusich]

test parameters:

• workflows = ph2_hlt

[mmusich]

@cmsbuild, please test

[cmsbuild]

+1

Size: This PR adds an extra 20KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-93ffee/53311/summary.html
COMMIT: 5d934e0
CMSSW: CMSSW_16_1_X_2026-05-18-1100/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/50967/53311/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 66
• DQMHistoTests: Total histograms compared: 4563745
• DQMHistoTests: Total failures: 2643
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 4561082
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 65 files compared)
• Checked 274 log files, 233 edm output root files, 66 DQM output files
• TriggerResults: found differences in 2 / 64 workflows

[jfernan2]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_16_1_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_17_0_X is complete. This pull request will now be reviewed by the release team before it's merged. @ftenchini, @sextonkennedy, @mandrenguyen (and backports should be raised in the release meeting by the corresponding L2)

[mandrenguyen]

+1