The filtering is done by tags. Triggering a task locally doesn't magically add tags, except for the user. For example, you can use:
https://chromium-swarm.appspot.com/tasklist?f=user%3Apcc%40chromium.org

I'll mark as WontFix because it works as intended, and filtering by user should be sufficient for the needs described here. Please reopen if filtering by user is insufficient.

It isn't because it doesn't allow me to filter out trybot-triggered jobs. This is what I get if I search for user:pcc@chromium.org (and extend the start time, which exposes the issue):

https://screenshot.googleplex.com/dyv7FBncxmA

I want to filter out everything except the top two lines.

When triggering locally, use the --tags flag. See ./swarming.py trigger --help for more information. The filtering is inclusive only, not exclusive. E.g. you can use == but not !=. Changing this is non trivial on the Cloud Datastore.