fix: don't reduce a composite primary key to its autoIncrement column

[h2zi]

Symptom

type Model struct {
    A int    `gorm:"primaryKey;autoIncrement"`
    B string `gorm:"primaryKey"`
}

AutoMigrate succeeds but creates (`a` integer PRIMARY KEY AUTOINCREMENT, `b` text) — B's primary-key declaration is silently dropped (related reports: #134, #126, glebarez#148).

Cause

DataTypeOf emits integer PRIMARY KEY AUTOINCREMENT for any auto-increment int field. When the rendered field type already contains PRIMARY KEY, GORM skips the table-level PRIMARY KEY (a, b) clause, so the composite key degrades to a single column.

Fix

AUTOINCREMENT only applies to a single-column INTEGER PRIMARY KEY in SQLite, so when the field is part of a multi-column key the clause is dropped and the table-level PRIMARY KEY (a, b) takes effect. Single-key behavior — including autoIncrement without an explicit primaryKey tag — is unchanged, verified by pragma_table_info in the test.

🤖 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]

🟢 Ready to approve

The change is narrowly scoped to SQLite type rendering for composite keys and is covered by a targeted regression test that reproduces the reported silent primary-key drop.

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Pull request overview

Fixes SQLite DDL generation for models that declare a composite primary key where one column is tagged autoIncrement, ensuring the composite key is preserved instead of being silently reduced to a single-column INTEGER PRIMARY KEY AUTOINCREMENT.

Changes:

• Prevent dataTypeOf from emitting integer PRIMARY KEY AUTOINCREMENT when the field participates in a multi-column primary key.
• Add a regression test asserting AutoMigrate preserves both primary-key columns for a composite key model.

File summaries

File	Description
sqlite.go	Avoids emitting INTEGER PRIMARY KEY AUTOINCREMENT for auto-increment fields in composite primary keys so table-level PRIMARY KEY(a,b) is not suppressed.
migrator_test.go	Adds a regression test that verifies composite primary keys retain all key columns after AutoMigrate.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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