fix(ddlmod): recognize the ? placeholder in constraint clauses

[h2zi]

Symptom

AutoMigrate on an existing table that is missing a foreign key declared in the model fails with:

table constraint_children__temp has no column named CONSTRAINT

Cause

CreateConstraint appends the constraint to the DDL field list in the form produced by constraint.Build(): CONSTRAINT ? FOREIGN KEY .... The constraintRegexp used by getColumns to filter out constraint clauses requires a backquoted constraint name, so the placeholder clause isn't recognized — the literal token CONSTRAINT is extracted as a column name and lands in the rebuild's INSERT INTO ... SELECT.

Fix

Accept a quoted or unquoted name as well as the ? placeholder, matching the more tolerant compileConstraintRegexp already used by addConstraint/removeConstraint. The now-unused sqliteColumnQuote is removed.

Covered by an end-to-end test: create the parent, create the child table without the FK, then AutoMigrate the child model — previously failing, now the constraint is added and data survives the rebuild.

🤖 Generated with Claude Code

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Merge order (this batch: #241 → #242 → #243 → #244 → #245 → #246, plus #234 from the previous batch): all seven are functionally independent and merge cleanly in any order. Several append tests to the same test files, so whichever merges later may show a trivial append-only conflict in migrator_test.go/ddlmod_test.go — I'll rebase the remaining ones promptly after each merge, as before.

[Copilot]

Pull request overview

Fixes SQLite AutoMigrate table-rebuild failures when GORM emits constraint clauses using the CONSTRAINT ? ... placeholder format, ensuring those clauses are not mis-parsed as column definitions during rebuild/copy.

Changes:

• Update DDL parsing to recognize CONSTRAINT ? ... (and more broadly tolerate quoted/unquoted constraint names) when filtering constraint clauses.
• Remove the now-unused sqliteColumnQuote constant.
• Add an end-to-end regression test that reproduces the failure and verifies data survival + FK creation after AutoMigrate.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
ddlmod.go	Broadens constraintRegexp so getColumns/DDL parsing skips CONSTRAINT ? ... clauses instead of treating CONSTRAINT as a column name.
migrator_test.go	Adds a regression test covering AutoMigrate of an existing table missing an FK, ensuring rebuild succeeds and data remains.

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