pkg/

Package applier defines decoded-change application contracts enforcing CO-4, CO-5, CO-6, and LK-3.

Package capabilities provides the embedded, validated support matrix and its Markdown renderer.

Package checkpoint defines durable resume contracts enforcing ST-1 and ST-2.

Package checksum defines shadow-fidelity contracts enforcing CO-1, CO-2, and CO-3.

Package copier defines chunked shadow-table copy contracts enforcing CO-4 and LK-3.

Package dbconn is the engine's database connectivity layer: pgx pool construction with safe session defaults (lock_timeout, statement_timeout), RDS/Aurora TLS, bounded retries for transient errors, and a helper to terminate backends blocking a session's lock acquisition.

Package decode defines logical-decoding contracts enforcing ST-4 and CO-4.

Package diffplan is the declarative front door as a library: a parsed desired-state schema in, the routed convergence plan out.

Package executor runs schema changes against the database.

Package lint checks DDL offline for patterns the engine would refuse, rewrite, or gate.

Package migrate is the imperative front door as a library: one parsed statement in — gate, resolve, introspect, classify, route, execute — and exactly one verdict out.

Package plan defines the machine-readable dry-run plan report: the stable JSON contract an operator or orchestrator consumes to decide whether and how a change would execute.

Package planner classifies schema-change statements: for each operation it decides whether PostgreSQL can run it online natively (possibly via a safer idiom it suggests), whether it needs the engine's copy-and-swap path, or whether it is refused.

Package preflight verifies preconditions before the engine writes anything (invariant ST-6).

Package progress defines the strategy-wide, machine-readable execution progress contract.

Package router assigns every classified statement to an execution backend.

Package schemachange orchestrates copy-and-swap schema changes while enforcing LK-2, LK-4, and ST-5.

Package schemadiff builds the canonical table model both front-ends share and diffs two models into an ordered statement list.

Package statement parses SQL through the real PostgreSQL grammar (wasilibs/go-pgquery, Wasm libpg_query) and reports the facts the engine's front door needs.

Package suggest is the advisory surface: it maps DDL that is risky as written to the safer native form the engine would run instead, offline and without executing anything.

Package verdict is the engine's structured outcome contract: every migrate invocation ends in exactly one verdict — executed natively, refused with a typed reason and, where one exists, a safer native idiom, or failed during execution with the executor's stable outcome code and a disclosure of what committed before the failure.