Dagster → Airflow 3 (Astro) migration

Migrate a Dagster project to Airflow 3 on Astro Runtime, honestly. The migration is asset-first (Dagster asset graphs translate to Airflow assets and asset-aware schedules, not flattened DAGs), incremental (domain by domain, Dagster stays authoritative until parity), and honest (every definition gets an explicit disposition; semantic deltas are documented, never papered over).

First time driving this? Read reference/quickstart.md first: hour-one commands, the glossary, and what can and cannot break.

Migration at a glance

1. Baseline the source project's tests, then inventory it read-only (scripts/inventory.py → manifest).
2. Review classifications (MECH/JUDG/REDESIGN/NONE per reference/mapping.md); make the go/no-go call (three outcomes; migrate-with-conditions is the common case, stay is the narrow one); plan DAG boundaries, per-edge IO decisions, and Gate 3 expectations into the manifest.
3. Trial-migrate 2-3 representative units end-to-end through every validation gate.
4. Migrate domain by domain through the six-gate ladder (reference/validation.md), tracking per-unit state (scripts/status.py); fix failure classes via reference/troubleshooting.md, never stub.
5. Map the platform layer (secrets, alerts, CI/CD, Deployments) per reference/astro-deployment.md.
6. Run side by side, then cut over per domain (consumers unpause first; see the checklist), keeping rollback one step away.
7. Deliver the migration report: every definition dispositioned, an equivalence row per trigger, losses stated plainly.

Version drift

Verified against Airflow 3.3.0 / Astro Runtime 3.3-2 / astronomer-cosmos 1.15 / Dagster 1.13 (2026-07). Version-sensitive rows in the references carry their floor (notably the 3.2-vs-3.3 partition surface). Before relying on a version-gated claim: check the target (airflow version, astro deployment inspect), probe imports for sdk surface (python3 -c "from airflow.sdk import X"), and prefer --help / API spec discovery over assuming verbatim CLI/REST contracts on newer versions. Playbook entries are version-scoped per entry.