fix(sdk/python): replace deprecated datetime.utcnow() with timezone-a…

[deensaleh]

…ware alternative

datetime.utcnow() is deprecated since Python 3.12 and scheduled for removal. It produces naive datetime objects with no timezone info, which causes DeprecationWarning on every test run across 5 files.

Additionally, two call sites combined .isoformat() + 'Z' on a timezone-aware datetime, producing invalid ISO strings like:
'2026-04-05T01:30:20.584591+00:00Z' ← double timezone suffix

This caused test failures in test_vc_generator.py.

Changes:

• agentfield/did_manager.py: add timezone import, utcnow → now(timezone.utc)
• agentfield/agent.py: utcnow → now(timezone.utc), fix isoformat+Z
• agentfield/client.py: datetime.datetime.utcnow() → datetime.datetime.now(datetime.timezone.utc)
• agentfield/vc_generator.py: add timezone import, utcnow → now(timezone.utc)
• tests/test_vc_generator.py: add timezone import, utcnow → now(timezone.utc), fix isoformat+Z

All 745 tests pass with 0 failures after this change. DeprecationWarnings reduced from 36 to 0.

Summary

Testing

• ./scripts/test-all.sh
• Additional verification (please describe):

Checklist

• I updated documentation where applicable.
• I added or updated tests (or none were needed).
• I updated CHANGELOG.md (or this change does not warrant a changelog entry).

Screenshots (if UI-related)

Related issues

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All committers have signed the CLA.

[github-actions]

Performance

SDK	Memory	Δ	Latency	Δ	Tests	Status
Python	9.3 KB	+4%	0.32 µs	-9%	✓	✓

✓ No regressions detected

[santoshkumarradha]

@deensaleh Thanks for the cleanup here, this is heading in the right direction. I noticed there are still a couple of client.py call sites building timestamps with datetime.datetime.now().isoformat() + "Z" for last_heartbeat and registered_at. Those are still naive local timestamps with a UTC suffix added afterward, so the timestamp handling is not fully consistent yet.

Could you update those remaining registration payload timestamps to use an actual UTC-aware datetime, and add a small test around that path in client.py? Right now the test coverage added in this PR is focused on vc_generator.py, so the client.py registration flow still is not covered.

Not blocking on this part, but it may also be worth using one small shared helper for outbound UTC timestamps so this does not drift across files again.

[deensaleh]

Good catch — updated. Added a `_utc_now_iso()` helper in `client.py` and replaced all 4 registration payload timestamps with it. Also added `TestUtcNowIso` (5 tests) covering the Z suffix, valid ISO parse, no double-offset, and millisecond precision. The other files you mentioned (`agent_server.py`, `agent_mcp.py`) have the same pattern — happy to extend in a follow-up PR if that's useful, but wanted to keep this one scoped to what you flagged.

…

On Sat, Apr 4, 2026 at 10:02 PM Santosh kumar ***@***.***> wrote: *santoshkumarradha* left a comment (Agent-Field/agentfield#332) <#332 (comment)> @deensaleh <https://github.com/deensaleh> Thanks for the cleanup here, this is heading in the right direction. I noticed there are still a couple of client.py call sites building timestamps with datetime.datetime.now().isoformat() + "Z" for last_heartbeat and registered_at. Those are still naive local timestamps with a UTC suffix added afterward, so the timestamp handling is not fully consistent yet. Could you update those remaining registration payload timestamps to use an actual UTC-aware datetime, and add a small test around that path in client.py? Right now the test coverage added in this PR is focused on vc_generator.py, so the client.py registration flow still is not covered. Not blocking on this part, but it may also be worth using one small shared helper for outbound UTC timestamps so this does not drift across files again. — Reply to this email directly, view it on GitHub <#332 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/B7QUYRAYKM2XODL4DHRT5NT4UHSHVAVCNFSM6AAAAACXM6XONCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DCOBYGI4TENBWGQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[santoshkumarradha]

Looks good now. Thanks for following up on the remaining client.py timestamp paths and adding coverage around the UTC helper.

[deensaleh]

Thanks Santosh. Glad the coverage landed well. AgentField's approach to cryptographic identity and verifiable execution trails is exactly the kind of infrastructure the space needs — happy to contribute more as the project grows.

…

On Sun, Apr 5, 2026, 1:37 AM Santosh kumar ***@***.***> wrote: Merged #332 <#332> into main. — Reply to this email directly, view it on GitHub <#332 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/B7QUYRFETVHXKHMOIHAIRRT4UILOLAVCNFSM6AAAAACXM6XONCVHI2DSMVQWIX3LMV45UABCJFZXG5LFIV3GK3TUJZXXI2LGNFRWC5DJN5XDWMRUGIYDINJVGQZDENA> . You are receiving this because you modified the open/close state.Message ID: ***@***.***>