# `mix attesto_mcp_server.gen.migration`
[🔗](https://github.com/XukuLLC/attesto_mcp_server/blob/v2.8.0/lib/mix/tasks/attesto_mcp_server.gen.migration.ex#L1)

Generates the Ecto migrations backing
`AttestoMCP.Server.SessionStore.Ecto` and
`AttestoMCP.Server.UrlElicitationStore.Ecto`.

The generated migrations create two PostgreSQL tables:
`attesto_mcp_sessions` and `attesto_mcp_url_elicitations`. Rows are keyed by
the namespace and an identifier so several independently named MCP servers
can safely share a repository.

The `attesto_mcp_sessions` table stores complete versioned session records as
JSONB in `record`; `created_at_ms`, `last_seen_ms`, `absolute_timeout_ms`, and
`idle_timeout_ms` mirror the record for validation, while `expires_at_ms` is a
denormalized value used for bounded SQL-side expiry filtering and cleanup.
A separate concurrent expression index supports per-principal admission. An
existing host can rerun this task to generate that index migration without
replacing its table migrations.

The `attesto_mcp_url_elicitations` table stores staged approval records with
their action, JSONB fields, timestamps, and optional consumed timestamp for
atomic single-use verification.

This task only writes migration files. It never invokes `Ecto.Migrator` or
changes the database. Apply the files from the host application's normal
migration workflow.

## Usage

    mix attesto_mcp_server.gen.migration --repo MyApp.Repo

## Options

  * `--help` - print usage and the accepted options, then exit without
    generating a migration.
  * `--repo` - the Ecto repo the migrations are generated for. It may be
    supplied more than once when several repos intentionally share the
    same application package. When omitted, configured Ecto repos are
    discovered using `Mix.Ecto`, and none or an ambiguous set is rejected.
  * `--schema-prefix` - an optional validated PostgreSQL schema used as
    Ecto's `prefix:` for every table and index. The schema is created with
    `CREATE SCHEMA IF NOT EXISTS` by the migration and is left in place on
    rollback. Table names are fixed because the runtime schemas query
    `attesto_mcp_sessions` and `attesto_mcp_url_elicitations`.
  * `--migrations-path` - directory in which migrations are written. It
    defaults to the repo's `priv/<repo>/migrations` directory. An explicit
    path may only be used with one repo so generation cannot partially
    write competing migrations into the same directory.
  * `--skip-url-elicitations` - do not generate the optional
    `attesto_mcp_url_elicitations` table. A host that does not use URL
    elicitation can rerun the task for later additions, such as the
    principal admission index, without that table coming back.

Each migration file is skipped when a file with that base name already exists
in the path. An existing host that reruns the task therefore receives only the
new file. Generated files are formatted and end with a newline, so they pass
`mix format --check-formatted` unchanged.

The generated migrations are idempotent: tables and indexes are created only
when absent and dropped only when present. The principal admission index
migration depends on the sessions table and fails before any DDL when that
table does not exist, so Ecto does not record it as applied and it runs again
once the sessions migration has been applied.

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*Consult [api-reference.md](api-reference.md) for complete listing*