fix(core): send NextToken when Hub.list_models pages through hub contents

[evakravi]

Problem

Hub.list_models() in sagemaker-core never returns on a hub with more than one page of contents. Hub._list_and_paginate_models reads NextToken from each list_hub_contents response but never sends it, so every call requests the first page and the loop never ends. On SageMakerPublicHub (743 models, 8 pages of 100) the call ran for 5 minutes without a result. The loop is the same in sagemaker-core 2.21.0 and in every v2 release with the hub module.

Solution

Pass the token as next_token on each call after the first. Session.list_hub_contents maps it to NextToken. #6262 is the same fix for v2.

Tests

A new unit test, sagemaker-core/tests/unit/jumpstart/hub/test_hub.py, serves each page once and raises KeyError on a second request for the same page. The old loop fails on its second call. On origin/master it fails with KeyError: ('ModelReference', None). On this branch it passes: 1 passed.

cd sagemaker-core && PYTHONPATH=src python -m pytest tests/unit/jumpstart/hub/test_hub.py

Live check with this branch against SageMakerPublicHub in us-west-2: Hub.list_models() returned in 2.6 s after 9 ListHubContents calls (1 ModelReference, 8 Model, 7 with NextToken). It returned 743 unique Model rows, each with OriginalCreationTime.

black==26.3.1 and flake8==7.1.2 pass on the new test. hub.py has 14 pre-existing pydocstyle findings and one pre-existing black diff on origin/master. This change adds none.

Merge Checklist

• I read the contribution guide.
• The change is backward compatible.
• The commits use the repository commit-message format.
• The change creates no S3 or STS client.
• The change has regression coverage and adds no dependency.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

Claude finished @evakravi's task in 53s —— View job

---

PR Review: fix(core): send NextToken when Hub.list_models pages through hub contents

• Read the PR diff (hub.py +2, test_hub.py +59)
• Verified the fix against Session.list_hub_contents mapping
• Reviewed correctness, tests, and edge cases

---

Verdict: LGTM ✅

The diagnosis and fix are correct. _list_and_paginate_models read NextToken from each response into next_token but never fed it back into the request, so every iteration re-fetched page 1 and while first_iteration or next_token never terminated. The two added lines fix exactly that.

I confirmed the token plumbing lines up end-to-end:

• hub.py:129-130 sets kwargs["next_token"] = next_token before subsequent calls.
• session_helper.py:2052-2054 reads kwargs.get("next_token") and maps it to the NextToken request field, then calls sagemaker_client.list_hub_contents.

So next_token (SDK) → NextToken (API) is the correct key, and the guard if next_token: correctly skips it on the first page and on empty/falsy tokens.

Things I checked that are fine

• No cross-call kwargs leakage. list_models invokes _list_and_paginate_models twice (once for ModelReference, once for Model), each with a freshly built dict unpacked via **{...}. Each call gets its own kwargs dict, so mutating kwargs["next_token"] in the reference pass can't leak into the model pass. The residual next_token left in kwargs after the loop is harmless since the loop has already exited.
• Termination. On the final page the response has no NextToken, so next_token becomes None and the loop exits — no off-by-one or extra empty request.
• Test quality. The test is well-constructed: pages.pop(...) guarantees each page is served exactly once, so the pre-fix infinite loop fails fast with KeyError instead of hanging, and assert pages == {} confirms every page (including the next_token-bearing ones) was actually requested. It exercises both content types and multi-page (page-2 → page-3) traversal.

Minor / optional (non-blocking)

• The test covers the paging mechanics well. If you wanted one more guard, an explicit assertion that the first request for each content type is sent without next_token (the ("...", None) keys already imply it, but only implicitly). Not necessary to merge.
• hub/ has no __init__.py, but the sibling test_interfaces.py/test_parsers.py live there too, so discovery is consistent with the existing layout — no action needed.

No correctness, security, or backward-compatibility concerns. The change is additive, matches the v2 companion fix (#6262), and has appropriate regression coverage.
• fix/jumpstart-hub-list-pagination-v3