[RaphaelFakhri]

What was changed

• SearchAttributes._to_proto_pair encodes TIME values with Time#iso8601(9) instead of Time#iso8601, so fractional seconds are no longer dropped.
• temporalio/search_attributes.rb now requires time, which provides Time#iso8601 and Time.iso8601.
• Adds test_search_attribute_time_sub_second to client_workflow_test.rb and a fixed changelog fragment.

Why?

Time#iso8601 with no argument writes whole seconds. A Time search attribute set to 08:00:00.123456789 is sent as 08:00:00Z, and that is what describe and list return. The server keeps the fraction: a raw Datetime payload with nanoseconds is returned unchanged, and the other SDKs send fractional seconds.

The SDK also never required time. On Ruby 3.3, an application that does not load it itself gets NoMethodError: undefined method 'iso8601' when it sets a TIME search attribute. The test suite does not catch this because its development dependencies load time.

Checklist

1. Closes [Bug] Time search attributes lose sub-second precision, and raise NoMethodError without require 'time' #653

2. How was this tested:

   • New test ClientWorkflowTest#test_search_attribute_time_sub_second starts a workflow with a nanosecond-precision TIME attribute and checks that describe returns the same Time. It fails before the change (expected 08:00:00.123456789 UTC, got 08:00:00 UTC) and passes after it.
   • WorkerWorkflowTest#test_search_attributes_memo passes.
   • A workflow that calls upsert_search_attributes with Workflow.now returns full nanoseconds in the workflow and in describe, with no illegal call errors.
   • Rubocop reports no offenses on the changed files.

3. Any docs updates needed? No.

[chris-olszewski]

Thanks for the find & fix!