feat: detect embedding model drift and add rebuild tool

[yeyitech]

Summary

• add persisted embedding compatibility metadata for local vectordb collections
• fail fast on server startup when the configured embedding identity no longer matches stored vectors
• add openviking-rebuild-vectors to delete stale per-account vectors and reindex all scopes from AGFS content
• cover metadata mismatch handling and rebuild traversal with targeted tests

Closes #1066.

Validation

• ruff check openviking/service/core.py openviking/service/vector_rebuild.py openviking/storage/embedding_compat.py openviking/storage/viking_fs.py openviking_cli/rebuild_vectors.py openviking_cli/utils/config/embedding_config.py openviking_cli/exceptions.py tests/storage/test_embedding_compat.py tests/service/test_vector_rebuild.py
• python -m compileall openviking/service/core.py openviking/service/vector_rebuild.py openviking/storage/embedding_compat.py openviking/storage/viking_fs.py openviking_cli/rebuild_vectors.py openviking_cli/utils/config/embedding_config.py tests/storage/test_embedding_compat.py tests/service/test_vector_rebuild.py
• python -m openviking_cli.rebuild_vectors --help
• manual validation harness for the new compatibility + rebuild logic (the repo still has the existing pytest-asyncio collection failure: AttributeError: 'Package' object has no attribute 'obj', so direct pytest collection is still blocked)

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 1066 - Partially compliant Compliant requirements: Record current embedding model identifier in metadata file Add openviking-rebuild-vectors tool to rebuild vectors Fail fast on startup with clear error when embedding model changes Non-compliant requirements: (No requirements violated, but implementation has bugs) Requires further human verification: Manual validation of the rebuild tool in real environment

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🏅 Score: 75

🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review NameError on Startup The initialize method uses an undefined variable config when calling ensure_embedding_collection_compatibility. This will cause a NameError and crash the server on startup. config, Blocking Sync Call in Async Function The fallback path for discover_accounts calls synchronous viking_fs.agfs.ls("/local") in an async function, which blocks the event loop. entries = viking_fs.agfs.ls("/local")

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Fix undefined config variable The variable config is not defined in the initialize method scope. Use self._config instead (the stored config instance) to avoid a NameError. openviking/service/core.py [281-286] if not self._embedding_compat_check_disabled(): await ensure_embedding_collection_compatibility( self._vikingdb_manager, - config, + self._config, config_path=os.environ.get("OPENVIKING_CONFIG_FILE"), ) Suggestion importance[1-10]: 9 __ Why: The variable config is indeed undefined in the initialize method scope; using self._config prevents a NameError, which is a critical correctness issue.	High
General	Remove blocking sync FS call The fallback path uses a synchronous viking_fs.agfs.ls("/local") call inside an async function, which blocks the event loop. Remove this fallback and require the async list_account_roots method, or wrap the sync call in a thread pool. openviking/service/vector_rebuild.py [53-56] -try: - entries = await viking_fs.list_account_roots() -except AttributeError: - entries = viking_fs.agfs.ls("/local") +entries = await viking_fs.list_account_roots() Suggestion importance[1-10]: 6 __ Why: The fallback uses a synchronous call inside an async function, which can block the event loop. Removing it aligns with the PR's addition of the async list_account_roots method.	Low