fix(migrations): stop 7bf4eac76958 renaming link constraints to a sha…

[manshusainishab]

Problem

A from-scratch flask db upgrade on PostgreSQL fails:

psycopg2.errors.DuplicateTable: relation "uq_pair" already exists
[SQL: ALTER TABLE cre_node_links ADD CONSTRAINT uq_pair UNIQUE (cre, node)]

Migration 7bf4eac76958 renames the unique constraints on both cre_links
(uq_cre_link_pair) and cre_node_links (uq_cre_node_link_pair) to the same
name uq_pair. On Postgres a UNIQUE constraint creates a schema-global index,
so the second uq_pair collides with the first — breaking any from-empty
migration on Postgres. (It slips by on SQLite, where batch_alter_table
rebuilds the table.)

Fix

Remove those two renames from 7bf4eac76958 (upgrade + downgrade). The preceding
migration 0d267ae11945 already creates the table-specific constraints, and the
SQLAlchemy models keep those names (uq_cre_link_pair / uq_cre_node_link_pair),
so we preserve them instead of collapsing both to uq_pair. The migration's
actual purpose (adding node.section_id and updating uq_node) is unchanged.

Validation

Full flask db upgrade from an empty PostgreSQL database now completes the entire
chain to head c7d8e9f0a1b2.

Note: completing the run also requires CRE_EMBED_EXPECTED_DIM to be set for the
pgvector migration (c7d8e9f0a1b2) on an empty DB — a separate, pre-existing
requirement of that migration, unrelated to this fix.

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📥 Commits

Reviewing files that changed from the base of the PR and between 2d1aa47 and e9a6b9f.

📒 Files selected for processing (1)

• migrations/versions/7bf4eac76958_add_rule_id_column.py

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Summary by CodeRabbit

• Bug Fixes
  • Updated database migration behavior to prevent unique-constraint naming conflicts in PostgreSQL.
  • Preserved existing uniqueness protections for link records while applying related schema updates safely.

Walkthrough

Changes

Migration constraint changes

Layer / File(s)	Summary
Remove link constraint renames migrations/versions/7bf4eac76958_add_rule_id_column.py	Upgrade and downgrade no longer rename unique constraints on cre_links and cre_node_links; remaining node constraint and section_id behaviors are unchanged.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: northdpole

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title matches the main change: it stops migration 7bf4eac76958 from renaming link constraints to a shared name.
Description check	✅ Passed	The description accurately explains the PostgreSQL migration failure and the fix to preserve table-specific constraint names.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Create PR with unit tests

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[manshusainishab]

@northdpole here is the PR with the fix as discussed I need a review and merge so I can take a fresh pull to continue with my next PR.