[danny-avila]

Summary

• Adds a new PGVECTOR_CREATE_EXTENSION env var (default True — back-compatible) that, when set to False, skips the CREATE EXTENSION IF NOT EXISTS vector call langchain's PGVector runs on startup.
• Plumbs a create_extension argument through get_vector_store into ExtendedPgVector/AsyncPgVector.
• Documents the new env var in the README.

Fixes a startup crash on managed Postgres (RDS, Azure Database for PostgreSQL, Cloud SQL, etc.) where the application user is not a superuser but the vector extension has already been pre-installed out-of-band. Without this flag, the container loops on psycopg2.errors.InsufficientPrivilege: permission denied to create extension "vector".

Closes #275, closes #99.

Test plan

• tests/services/test_vector_store_factory.py — added test_get_vector_store_defaults_create_extension_true and test_get_vector_store_propagates_create_extension_false covering both sync and async modes.
• Manual: deploy with PGVECTOR_CREATE_EXTENSION=False against a Postgres instance where the app user is not a superuser and vector is pre-installed — container should start cleanly.
• Manual: deploy without the env var set — behavior should be unchanged (extension creation attempted as today).

🤖 Generated with Claude Code

[danny-avila]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 🚀

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