# `Cyclium.Migrations.V25`
[🔗](https://github.com/Cyclium/cyclium_ex/blob/main/lib/cyclium/migrations/v25.ex#L1)

V25: Add an open `metadata` bag (`:map` → nvarchar(max) via TDS) to
`cyclium_episodes` and `cyclium_episode_steps`.

Every existing `:map` column on these tables has a specific, framework-owned
purpose (`trigger_ref`, `budget`, `classification`, `error_detail`,
`dry_run_opts`, `args_redacted`, `result_ref`), so there was no place to hang
per-run attributes — most importantly *which model/LLM actually ran*. The
model is actor-level config resolved at runtime and observable in Datadog
(`llm_model`), but it was not queryable in the DB.

`metadata` is a general key/value bag so new per-run attributes don't each need
a migration:

  * On `cyclium_episodes` it holds the **primary** model the episode ran under
    (e.g. `%{"model" => "gpt-5.4-2026-03-05"}`), stamped once.
  * On `cyclium_episode_steps` it records a model **only when that step
    diverges** from the episode's primary model, so a single-model episode
    doesn't repeat the model on every synthesis step.

Nullable with no default, matching the other `:map` columns (a SQL default of
`%{}` isn't portable to the nvarchar(max) representation); the app layer
treats `NULL` as the empty bag.

# `down`

# `up`

---

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