[BUG] Zagreb Electric Tram - Arrivals Unknown

[bojankoma]

Describe the bug
A clear and concise description of what the bug is.

Feed Related Bug

Feed compatibility may change based on provider outages or changes in API. Bugs should not be reported for provider outages.

• This bug is related to feed compatibility
  List Feed(s) affected:

• My custom feed I've been testing in user_feeds.json for Zagreb Electric Tram.

• Feed resources can be accessed directly from the URL or the feed provider's website

• I have confirmed this is not related to a provider's outage

To Reproduce
Steps to reproduce the behavior:

1. Add Zagreb Electric Tram data found here user_feeds.json
2. Configure the Zagreb Electric Tram
3. Select Route IDs 4 and 11
4. Select both Poljanice IV stop (256_1 and 256_2)
5. Submit configuration
6. Created entity arrivals are always Unknown, sometimes 0 minutes.

Expected behavior
I would expect the realtime data to be pulled every 5 to 10 minutes and refreshed.
Entities should display minutes in their arrival sensors.

Screenshots

Logs
Attached logs here:

config_entry-gtfs_realtime-01KANRHTBABVMW608TZJQP334K.json

Home Assistant
Version: 2025.11.3
Install Method

• HAOS
• Container
• Other

Additional context
Thank you for your great work, you saved me weeks of developing this integration. It's exactly what I was looking for. I have a few options to offer as help and more context:
a) I do suspect that my provider data might not be 100% up to standard. I suspect that stop IDs 256_1 and 256_2 have the suffix of directional platforms XYZ_1 and XYZ_2 (where XYZ is 256 here in my example). That suffix probably isn't matched or mixed in properly in trip information.
b) On the other hand, maybe trip information isn't updated as frequent in this HA integration - my provider allows 5 to 10 minute intervals. Meaning, that 0m value of arrival happens when a GTFS update protobuf is downloaded and parsed at exact time when a tram arrives on the stop. Else it isn't included in trip info update, hence Unknown.

Please let me know of anything I can do or provide more details, I'd like to eventually do a PR and include Zagreb GTFS in main branch and production release.

[bcpearce]

@bojankoma thanks for the report and for trying out the integration. I'll see if I can take a look at it soon. At first glance it seems really similar to #43, where I found that the feed only reported realtime updates as a change from the static schedule. It would probably require changes to the underlying library https://github.com/bcpearce/gtfs-station-stop to allow reporting scheduled trips as well as realtime trip updates.

[bojankoma]

@bcpearce I'm not sure if it helps but...
I did use the underlying library gtfs-station-stop to smash together an ugly test script:

import time
import FeedSubject
import StationStop

urls = ["https://www.zet.hr/gtfs-rt-protobuf"]
feed_subject = FeedSubject(urls)

while True:
    station_stop_nb = StationStop("256_1", feed_subject)
    station_stop_sb = StationStop("256_2", feed_subject)

    feed_subject.update()

    for arrival in station_stop_nb.arrivals:
        minutes_to = (arrival.time - time.time()) / 60.0
        print(f"{arrival.route} in {minutes_to:.1f} at {station_stop_nb.id}")

    for arrival in station_stop_sb.arrivals:
        minutes_to = (arrival.time - time.time()) / 60.0
        print(f"{arrival.route} in {minutes_to:.1f} at {station_stop_sb.id}")

    print(f"---")

    time.sleep(10)

... and I do get results as expected and can confirm actual trams are arriving at the given time:

4 in -2.2 at 256_1
4 in -4.3 at 256_2
---
4 in -2.3 at 256_1
4 in -4.5 at 256_2
---
4 in -2.5 at 256_1
4 in -4.7 at 256_2
---
4 in -4.9 at 256_2
---
4 in -5.0 at 256_2
---
4 in -5.2 at 256_2
---
4 in -5.4 at 256_2
11 in 1.3 at 256_2
---
11 in 1.3 at 256_2
---
11 in 1.3 at 256_2
---
11 in 1.3 at 256_2
---
11 in 1.4 at 256_2
---
11 in 1.2 at 256_2
---
11 in 1.0 at 256_2
---
11 in 0.5 at 256_2
---
11 in 0.0 at 256_2
---
11 in -0.1 at 256_2
---
11 in -0.2 at 256_2
---
11 in -0.4 at 256_2
---
11 in -0.6 at 256_2
---
11 in -2.9 at 256_1
11 in -0.7 at 256_2
---
11 in -0.9 at 256_2
---
11 in -1.1 at 256_2
---

To my surprise, my data provider seems to follow some sort of standard after all.
I had to pull (update) data periodically to get the output.
Perhaps adding a new input field in HA offering hour/minute to select the period of refreshing the trip update data, just like static data?

[EDIT] Just read your reply again. OK, I get it, scheduled trips aren't included at the moment. Thanks, I'll wait for the update then.

[ilaktasic]

Hi @bojankoma I managed to integrate ZET with https://github.com/vingerha/gtfs2, feel free to contact me if you need more details.