Artifacta MCP vs MCP Memory Gateway

list_sessions

List session IDs synthesized from the calling tenant's artifacts, ordered by most recent activity. Each entry includes artifact count, seal status, and first/last activity timestamps. Sessions are not first-class — they exist only as long as artifacts reference them.

store_artifact

Upload a file as a new artifact in a single call. Provide EITHER up to ~10 MB of base64-encoded bytes via `content`, OR a local filesystem `path` that the MCP server reads and streams as multipart/form-data (up to 500 MB). For files larger than 500 MB, use `request_upload_url` (Pro only) instead — `store_artifact` returns `file_too_large` for them. Tags the artifact with `session_id` / `agent_id` / `metadata` for later retrieval and returns the full artifact record including its new `artifact_id` and `content_hash`. Path uploads are confined. The `path` argument is constrained to the launcher-configured allow-list (default: the MCP server's CWD). Paths outside the allow-list, paths traversing symlinks out of it, and paths to known-sensitive locations (`~/.ssh`, `~/.aws`, `/etc/`, etc.) are refused with `invalid_request`. For crash-safe retries, supply your own `idempotency_key` (any string ≤256 chars): a replay within 24h returns the original artifact and never double-bills. If you omit it, the server auto-generates one and returns it under `_meta.idempotency_key`, but that key protects only in-process retries within a single call — it is lost if the server restarts, so pre-commit your own key when durability matters.

request_upload_url

Reserve a presigned R2 PUT URL for a file too large to send through `store_artifact` (over 500 MB up to 5 GB). Returns an `upload_url`, headers to include in the PUT, and an `artifact_id` in `pending` state. The agent (or its environment) PUTs the bytes directly to R2, then calls `complete_upload`. Pro plan only. Most agents should use `store_artifact` and let the MCP server pick the path automatically. Not retry-safe: this endpoint does not support idempotency keys, so on an HTTP 5xx or network error the reservation may or may not have been created. Do NOT blindly retry — the error guidance tells you to first call `list_artifacts` with the same `session_id`/`agent_id` to detect any pending artifact, so you don't create a duplicate.

complete_upload

Finalize an artifact previously reserved via `request_upload_url` after the bytes have been PUT to the presigned URL. Server verifies the blob, computes the content hash, transitions the artifact from `pending` to `active`, and increments tenant usage. Calling this on an already-active artifact is idempotent and returns the existing record. Calling before the PUT completes returns `upload_not_found` — wait and retry.

publish_artifact

Publish an existing artifact as a polished, shareable public page at https://artifacta.io/a/{slug}. Composes with store_artifact (store first, then publish). Returns a public_url anyone can open without an Artifacta account. Default visibility is unlisted (link-only); pass visibility:"public" for gallery-eligible later. Idempotent: re-publishing the same artifact_id updates the existing page and keeps the same URL.

unpublish_artifact

Remove the public page for an artifact, making the public URL inaccessible. The artifact itself is not deleted — only its shareable page is taken down. The URL stops resolving immediately. Idempotent: calling unpublish on an already-unpublished artifact is a no-op.