ocaml-opam-tinyflags-rollout-review

name	ocaml-opam-tinyflags-rollout-review
description	Review TinyFlags flag definitions and call sites for safe OCaml rollouts.

TinyFlags Rollout Review

Use this skill before increasing rollout percentages or shipping a new TinyFlags-backed behavior in an OCaml package.

Review Checklist

• Every flag definition passes an explicit ~default argument.
• Boolean rollouts use int values in 0..100.
• Variant rollout totals do not exceed 100.
• Unknown variants are not referenced in rollout pairs.
• Evaluation contexts include a stable Tinyflags.Context.t with a meaningful id (user, session, or account identity).
• alcotest specs exercise both default and rollout-allocated paths.
• No match arm assumes rollout bucketing is random per request.

OCaml Details

Check that flag construction is centralized — a single Tinyflags.make_exn [ ... ] call inside the project's flags module is the target of review. Scattered registries make rollouts hard to reason about.

let flags =
  Tinyflags.make_exn
    [
      ("checkout-redesign",
       Boolean (Tinyflags.Bool.make_exn ~default:false ~rollout:10 ()));
    ]

Build evaluation contexts at the request boundary, not at every call site:

let context = Tinyflags.Context.make ~id:request.user_id ()

Rollout changes should be small and reviewable. If a rollout moves from 0 to 100, confirm the disabled branch can be deleted or document why the flag remains temporary.