# Evidence sources Canonical HTML: https://spoolis.com/docs/sources. This page is also available in machine-readable Markdown. Connect arbitrary systems through immutable evidence capsules and reproducibly derived facts. ## Source contract Sources declare authentication, pagination, checkpointing, replay, schema-change, deletion, correction, and health semantics. Tier 0 supports CSV, JSON, file upload, HTTP with OpenAPI, signed webhooks, read-only SQL, S3-compatible object storage, and CloudEvents. ## Capsules and facts Capsules and facts are immutable and content-addressed. Evidence from another system is what Spoolis observed, with provenance. It is not truth by itself. Spoolis maintains the canonical accepted commercial state under the agreement's rules and authority model. ## Machine surfaces Use the source API, list_sources, add_source, sync_source, list_facts, or the matching CLI commands. Replayed jobs are no-ops and failed chunks retain their checkpoints.