feat(lint): flag a CONCURRENTLY operation inside a transaction block

[aparajon]

Why

PostgreSQL refuses every CONCURRENTLY form inside an explicit transaction block. Many schema change tools wrap each file in BEGIN … COMMIT, so a file that adds an index the safe way still fails at that statement and rolls back. Lint flagged BEGIN and COMMIT as unrecognized, but said nothing about the statement that actually breaks.

What

• Lint tracks the block a script opens and reports each CONCURRENTLY operation inside it as concurrent-in-transaction, an error. That covers CREATE INDEX, DROP INDEX, REINDEX, and DETACH PARTITION.
• A savepoint, or a COMMIT AND CHAIN that opens the next block at once, keeps the script inside its block. COMMIT, ROLLBACK, and PREPARE TRANSACTION close it.
• statement.TransactionControlOf reads those statements from the parse tree, so lint never matches on text.
• The lint report moves to format_version 3, since a new code is a contract change. docs/lint-report.md and the reference doc describe the code.
• An integration test runs each flagged form inside a block against a real server and requires it to be refused with active_sql_transaction.

New text output

$ pg-sprite lint changes.sql
changes.sql:2:1:
  CREATE INDEX CONCURRENTLY i ON t (c);

error[concurrent-in-transaction]:
  CREATE INDEX i — PostgreSQL refuses CONCURRENTLY inside a transaction
  block, so the script fails here and the block rolls back

help:
  run this statement on its own, outside the BEGIN … COMMIT block

docs:
  https://github.com/block/pg-sprite/blob/main/docs/postgres-online-ddl-reference.md#concurrent-in-transaction

Before this change the same statement printed no finding; only BEGIN and COMMIT were flagged, as unrecognized operations.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Explicitly disabled REINDEX concurrency incorrectly triggers the new transaction error.

1 open issue

• Decode REINDEX CONCURRENTLY false before enforcing transaction restriction · New

What changed in this PR

Adds script-level transaction tracking to pg-sprite lint so concurrent operations inside explicit transaction blocks produce an error.

Changes:

• Parses transaction controls and emits concurrent-in-transaction findings.
• Adds unit, renderer, and PostgreSQL integration tests.
• Updates the lint report to version 3, documentation, and demo assertions.

File	Description
pkg/​statement/​transaction.go	Parses transaction-control effects.
pkg/​statement/​transaction_test.go	Tests transaction-control classification.
pkg/​lint/​transaction_integration_test.go	Checks PostgreSQL refusal of concurrent operations.
pkg/​lint/​lint.go	Tracks blocks and emits the new diagnostic.
pkg/​lint/​lint_test.go	Tests block tracking and report version.
internal/​cli/​lint_text.go	Renders diagnostic explanation and help.
internal/​cli/​lint_test.go	Tests diagnostic text output.
docs/​postgres-online-ddl-reference.md	Explains the new diagnostic.
docs/​lint-report.md	Documents version 3 and the new code.
docs/​cli-output-examples.md	Updates the JSON example version.
demo/​tour.sh	Expects lint report version 3.

_{Review effort: Balanced}