fix: restore vectors when segments are re-enabled via API

[jasonfish568]

Summary

Fixes #39988.

The Service API used the segment update path for enabled: true. After a segment was disabled, its vector had already been deleted, so updating the missing Elasticsearch document did not restore it.

This change reuses the existing enable flow used by the Web Console when the request only sets enabled: true. Requests that also change content or keywords keep the current update behavior. This keeps Web and Service API behavior on the same code path and avoids duplicating indexing logic.

Validation

• make lint
• make type-check
• make test TARGET_TESTS=api/tests/unit_tests/services/test_dataset_service_segment.py (44 passed)
• Docker E2E with Tongyi embedding and Elasticsearch: disable removed the vector, API-only enable recreated it, and retrieval returned the segment

From Codex

[github-actions]

Pyrefly Diff

base → PR

--- /tmp/pyrefly_base.txt	2026-08-05 13:06:44.221520285 +0000
+++ /tmp/pyrefly_pr.txt	2026-08-05 13:06:30.413423296 +0000
@@ -7663,13 +7663,13 @@
 ERROR Argument `SimpleNamespace` is not assignable to parameter `dataset` with type `Dataset` in function `services.dataset_service.SegmentService.delete_child_chunk` [bad-argument-type]
    --> tests/unit_tests/services/test_dataset_service_segment.py:280:64
 ERROR Argument `SimpleNamespace` is not assignable to parameter `segment` with type `DocumentSegment` in function `services.dataset_service.SegmentService.update_child_chunk` [bad-argument-type]
-   --> tests/unit_tests/services/test_dataset_service_segment.py:953:49
+    --> tests/unit_tests/services/test_dataset_service_segment.py:1010:49
 ERROR Argument `SimpleNamespace` is not assignable to parameter `document` with type `Document` in function `services.dataset_service.SegmentService.update_child_chunk` [bad-argument-type]
-   --> tests/unit_tests/services/test_dataset_service_segment.py:953:68
+    --> tests/unit_tests/services/test_dataset_service_segment.py:1010:68
 ERROR Argument `SimpleNamespace` is not assignable to parameter `dataset` with type `Dataset` in function `services.dataset_service.SegmentService.update_child_chunk` [bad-argument-type]
-   --> tests/unit_tests/services/test_dataset_service_segment.py:953:87
+    --> tests/unit_tests/services/test_dataset_service_segment.py:1010:87
 ERROR Argument `SimpleNamespace` is not assignable to parameter `dataset` with type `Dataset` in function `services.dataset_service.SegmentService.delete_child_chunk` [bad-argument-type]
-   --> tests/unit_tests/services/test_dataset_service_segment.py:967:60
+    --> tests/unit_tests/services/test_dataset_service_segment.py:1024:60
 ERROR Argument `str` is not assignable to parameter `type` with type `Literal['basic', 'bearer', 'custom'] | None` in function `services.entities.external_knowledge_entities.external_knowledge_entities.AuthorizationConfig.__init__` [bad-argument-type]
    --> tests/unit_tests/services/test_external_dataset_service.py:119:60
 ERROR Argument `str` is not assignable to parameter `type` with type `Literal['api-key', 'no-auth']` in function `services.entities.external_knowledge_entities.external_knowledge_entities.Authorization.__init__` [bad-argument-type]

[github-actions]

Pyrefly Type Coverage

Metric	Base	PR	Delta
Type coverage	57.36%	57.36%	-0.00%
Strict coverage	56.94%	56.94%	-0.00%
Typed symbols	37,032	37,032	0
Untyped symbols	27,731	27,735	+4
Modules	3103	3103	0