Tuist Elixir Review

Tuist Elixir Review

This skill is intentionally narrow. Generic Elixir style, naming, pipe chains, formatting, nesting depth, and String.to_atom/1-style hygiene are already covered by mix format and credo in CI — do not flag those. Focus on the rules below; they catch real bugs.

For each finding, cite path:line (or Module.function/arity) and quote the relevant snippet.

Only report findings whose cited snippet is present in the PR diff. If the concern comes from unchanged context, do not emit a finding, do not mention it as a note, and do not create a "findings outside this PR's diff" section. If every possible concern is outside the diff, return no findings.

Do not infer violations from nearby lines. A Mimic finding requires the exact token Mimic.copy( on the cited changed line. A migration timestamp finding requires the cited changed line to contain timestamps() without type: :timestamptz or a timestamp column without :timestamptz.

1. Authorization — lib/tuist/authorization.ex + AuthorizationPlug

The policy DSL is LetMe.Policy. Categories are declared via object :foo do ... end blocks. The API plug at server/lib/tuist_web/plugs/api/authorization/authorization_plug.ex hard-codes which categories are project-scoped:

@project_categories [:run, :bundle, :cache, :preview, :test, :build, :automation_alert]

Flag

• A new object :foo do block (project-scoped resource) without :foo being added to @project_categories in authorization_plug.ex. The route guard will silently miss the new category. Severity: high.
• An action that uses [:authenticated_as_project, ...] but omits :projects_match. This lets an authenticated project act on another project's resource. Severity: critical. The canonical correct form is allow([:authenticated_as_project, :projects_match]).
• :public_project or [:authenticated_as_user, :ops_access] allowed for :create, :update, or :delete actions. These flags are intended for read-only paths.
• A new action :read | :create | :update | :delete that doesn't cover all three subject kinds (:authenticated_as_user, :authenticated_as_project, :authenticated_as_account with a scopes_permit: check) without an inline desc(...) explaining the omission. Missing one is usually a bug; an explicit desc is the documented escape hatch.
• An account-token allow without a scopes_permit: check (e.g. bare [:authenticated_as_account]). Account tokens must always be scope-gated.

Do not flag

• Existing object/action blocks unchanged by the diff.
• Reordering of allow(...) lines within an action.
• /ops LiveView routes. They are not API AuthorizationPlug categories and do not belong in @project_categories.

2. Tenancy — bare Repo.get on multi-tenant schemas

Tenant-owned schemas include at least: Bundle, Run, Cache, Preview, CommandEvent, Build, Test, Project, AutomationAlert. They all carry a project_id or account_id.

Flag

• Tuist.Repo.get(Schema, id) / Repo.one(from(s in Schema, where: s.id == ^id)) without a project_id / account_id constraint for any of the schemas above, when the call is inside a controller, plug, LiveView, channel, MCP handler, or worker that already has the project/account in scope. This is a tenant leak (an attacker who guesses a UUID gets cross-tenant data). Severity: high.
• A new context function that takes an id and forwards it to Repo.get without also taking the project/account.

Do not flag

• Internal background jobs that intentionally operate across tenants (look for an explicit # admin / cross-tenant: ... comment or a function name like *_for_all/_global/_admin).
• Reads from non-tenant tables (User, Account, Organization, Subscription, etc.).
• Webhook handlers operating on a row that was already cryptographically selected upstream. When lib/tuist_web/plugs/webhook_plug.ex resolves a per-row HMAC secret (e.g. GitHubController.resolve_webhook_secret/1 matches a GitHubAppInstallation row whose webhook_secret HMACs the raw body, then stashes the row on conn.assigns[:github_installation]), downstream handlers reading that assign do not need a separate installation.account_id == expected_account_id check. There is no separate "expected account" — webhooks land on a global /webhooks/<provider> URL, and the row is the tenant context, selected by a per-row cryptographic capability. A redundant account_id equality check after valid_signature?/4 would compare the row's value to itself; it adds dead code, not a defense layer. If the cryptographic check fails, the request 403's before the handler ever runs.
• Internal dispatch paths whose inputs come from a query already scoped by tenant. When a function receives a struct produced by an upstream context function that already filters by project_id / account_id (e.g. FlakyTestsMonitor.evaluate/1 → AlertEvaluationWorker → ActionExecutor), do not flag the downstream call as needing its own scoping check. Trace the input chain before flagging; only flag when the input is user-controllable (URL param, body field, header).

3. ClickHouse IngestRepo is write-only

There are two ClickHouse repos in this codebase, and they are not interchangeable. Be precise about which one a call uses before flagging.

• Tuist.IngestRepo — write-only ingest path. Application code must not read from it; reads happen out of band.
• Tuist.ClickHouseRepo — the read-only ClickHouse repo (declared with read_only: true in server/lib/tuist/clickhouse_repo.ex).

Flag (Severity: high)

• Any call to Tuist.IngestRepo.all/1, Tuist.IngestRepo.get/2, Tuist.IngestRepo.get_by/2, Tuist.IngestRepo.one/1, Tuist.IngestRepo.exists?/1, or Tuist.IngestRepo.aggregate/3.
• Any from(... ) |> Tuist.IngestRepo.<read fn>.

The fix is almost always to read through Tuist.ClickHouseRepo (for ClickHouse-only data) or Tuist.Repo (PostgreSQL).

Do not flag

• Tuist.ClickHouseRepo.all/1, Tuist.ClickHouseRepo.one/1, Tuist.ClickHouseRepo.aggregate/3, or any other read through ClickHouseRepo. That repo exists specifically for application reads. Do not confuse it with IngestRepo.
• Writes via Tuist.IngestRepo.insert/2 / insert_all/2,3 — those are the intended use.

4. Test setup — Mimic copies belong in test_helper.exs

server/test/test_helper.exs is the single place where Mimic.copy(Module) is called. Per-test-file Mimic.copy/1 calls leak state across tests and are an explicit anti-pattern in this repo.

Flag

• A Mimic.copy(...) call inside any file under server/test/ other than test_helper.exs. Suggest: move it to test_helper.exs.

Do not flag

• Mimic.expect/3, Mimic.stub/3, Mimic.reject/1 — those belong in tests.
• Mimic.copy/1 calls in test_helper.exs itself.
• import Mimic, use Mimic, setup :set_mimic_from_context, aliases, or any other test setup line that does not contain Mimic.copy(.
• A test file that merely uses Mimic (use Mimic, import Mimic, stub, expect, reject) but does not contain the exact Mimic.copy( call in the diff.

5. Migrations — timestamps must be timezone-aware

In server/priv/repo/migrations/ and server/priv/ingest_repo/migrations/:

Flag (Severity: medium)

• A new column declared as timestamps() without type: :utc_datetime_usec and a corresponding migration column without :timestamptz. The .credo.exs rule says: migrations use :timestamptz, schemas (lib/) use :utc_datetime.
• add :inserted_at, :naive_datetime or :datetime without timezone in a migration. Should be :timestamptz.

Do not flag

• timestamps(type: :timestamptz).
• def change do, create table(...), blank lines, comments, or any line that does not itself declare a timestamp type.
• add :started_at, :timestamptz, add :finished_at, :timestamptz, or any other explicit :timestamptz column.

6. data-export.md updates on schema changes

server/data-export.md documents every piece of customer data Tuist stores, for GDPR Article 20 / CCPA exports. It must be updated when the diff includes any of:

• A new migration adding a table
• A new migration adding a column that stores customer / user / project data (not internal bookkeeping)
• A new Ecto schema in server/lib/tuist/**/*.ex that maps to a customer-facing table
• New file storage paths in S3 (e.g. new keys under bundles/, previews/, caches/)

Flag (Severity: medium)

• A diff that touches server/priv/repo/migrations/*.exs (other than pure index / constraint changes) or server/priv/ingest_repo/migrations/*.exs without also modifying server/data-export.md.

This is a compliance gap, not just a docs nit — call it out clearly.

7. i18n — currency symbols are not translatable

In marketing copy and pricing UI:

Flag

• Currency amounts (€, $, £, ¥, currency codes) wrapped inside dgettext/2 or gettext/1. Symbols and amounts must remain identical across languages.
• Example anti-pattern: dgettext("marketing", "0€ and up"). The correct form keeps the currency literal outside the translation: "0€ " <> dgettext("marketing", "and up").

Do not flag

• Descriptive text around prices (e.g., the words "and up", "per unit", "billed annually") — those should be translated.

8. Translation files — .po is read-only for humans

Flag (Severity: high)

• Any modification to server/priv/gettext/**/*.po. Only the tuistit bot may edit .po files; CI will fail otherwise.
• Use of mix gettext.extract --merge. Only the no---merge form is allowed in PRs.

Do not flag

• .pot (template) changes — those are produced by mix gettext.extract and are expected when adding new translatable strings.

9. N+1 queries — DB calls inside loops

A Repo.* / ClickHouseRepo.* / IngestRepo.* call inside Enum.map, Enum.each, Enum.flat_map, Enum.filter, Enum.reduce, for, or Stream.* is almost always an N+1. Each iteration is a separate round trip; the chart-bucket loop or per-row preload that looked harmless on toy data stalls real page loads.

Actively search the diff for these patterns before signing off — don't just react to obvious cases:

• Enum.map(_, fn ... -> ... <Repo>.<one|all|get|get_by|aggregate|exists?|stream> ... end)
• Enum.map(_, &<Repo>.<...>(&1, ...)) (point-free form is the same trap)
• Enum.each(_, fn ... -> ... <Repo>.<insert|update|delete> ... end)
• Enum.flat_map, Enum.reduce(..., fn _, acc -> ... <Repo>... end)
• for x <- xs, do: <Repo>.* / for x <- xs, do: ... with a query inside
• Enum.map(_, &<Repo>.preload(&1, ...)) — preload/2 already accepts a list
• Pipelines like xs |> Enum.map(&fetch_thing/1) where fetch_thing/1 internally calls a Repo — follow the function one hop in.

The repos to watch: Tuist.Repo, Tuist.ClickHouseRepo, Tuist.IngestRepo, plus any aliased form (e.g. alias Tuist.Repo, then bare Repo.* inside the loop).

Flag (Severity: medium; high if hot path)

• A Repo/ClickHouseRepo/IngestRepo read or aggregate inside any Enum.*/for/Stream.* in the diff. Severity is high if the loop is on a request path (controller, LiveView mount/handle_*, channel, MCP handler) or scales with tenant data (test cases, bundles, runs); medium for background jobs and one-shot scripts.
• Per-element Repo.preload/2 — preload already takes a list; one call covers all.
• Per-element inserts/updates/deletes that have an _all equivalent (insert_all, update_all, delete_all).

When suggesting a fix, name the consolidating primitive so the author can act on it directly:

• ClickHouse per-bucket aggregation → argMaxIf / countIf / groupArray over a single GROUP BY, or arrayJoin to fan out buckets as rows.
• Ecto per-row lookup → where: r.id in ^ids + group in Elixir, or a join.
• Per-element preload → Repo.preload(list, [:assoc]) once.
• Per-element write → *_all + a list of params.

Do not flag

• Loops over a bounded constant collection (config keys, enum members, ≤5 items) where each query is genuinely independent and the loop isn't on a hot request path.
• Tests, fixtures, and seed scripts (server/test/, server/priv/repo/seeds*.exs) — correctness-first, perf is fine.
• Loops that build params in memory with no DB round trip per iteration.
• Repo.stream/2 inside Enum.* with an explicit comment justifying the cursor-based stream (e.g. "stream so we don't load 10M rows").
• Pre-existing N+1s untouched by the diff — this skill is for new regressions, not codebase-wide audits.

10. Inline style="..." in HEEx templates

Component styling lives in server/assets/app/css/pages/*.css (or noora/lib/noora/**/*.css for design-system primitives), keyed off data-part selectors that mirror the HEEx structure. Inline style= attributes on elements or component props bypass the design tokens (var(--noora-spacing-*), var(--noora-font-*), etc.) at review time, leak presentation into LiveView diffs, and prevent themers / density modes from overriding the value.

Flag (Severity: low)

• A new style="..." attribute on an HTML element inside any server/lib/tuist_web/**/*.html.heex or *_live.html.heex.
• A style= prop passed to a Noora component (<.button_group style="...">, <.text_input style="...">, etc.). These flow through to the underlying element via {@rest}, so they're inline styles by another name.

When suggesting a fix:

1. Add a stable data-part (or reuse one already on the element).
2. Move the rule into the matching page CSS file (server/assets/app/css/pages/<page>.css) or, if it belongs to a reusable component, the Noora primitive's CSS.
3. Prefer Noora design tokens (--noora-spacing-*, --noora-radius-*, --noora-font-*, --noora-surface-*) over raw values.

Do not flag

• style= attributes that already existed before the diff.
• Generated SVG markup with inline styles (it's the artist tool's output, not author-written).
• One-off style="display: none" toggles whose visibility is driven by a temporary Phoenix :if — those still belong in CSS, but the signal-to-noise here is low.

11. Marketing changelog for user-facing server/dashboard features

The human-authored product changelog lives in server/priv/marketing/changelog/*.md. Generated files such as server/CHANGELOG.md or root CHANGELOG.md must not be edited by authors.

Flag (Severity: medium)

• A PR that adds or materially changes a user-facing server/dashboard feature without also adding or updating a server/priv/marketing/changelog/*.md entry.
• A PR that adds or updates a server/priv/marketing/changelog/*.md entry for a feature that is ops-only, admin-only, feature-flagged only for internal rollout, infrastructure-only, or otherwise not meant to be announced to customers yet.

User-facing signals include changed dashboard routes, LiveViews, controllers, templates, page CSS, settings pages, integration flows, alerts, reports, previews, build/test/cache/bundle analytics, or public API behavior that customers can observe.

Do not treat a dashboard/UI change as announceable only because it lives in user-facing code. If the diff gates the behavior behind an account/org feature flag, ops/admin-only access, or an explicit internal rollout path, it is not ready for the product changelog unless the PR also makes that behavior broadly available to customers.

Do not request a product changelog for fix PRs. This includes fixes that add or adjust dashboard fields, copy, validation, or settings controls when those UI changes are part of making an already-announced or already shipped flow work correctly. Only ask for a changelog when the PR's primary purpose is to launch a new customer-facing capability, not when the PR is repairing or completing a broken flow.

When suggesting a fix, ask for a short marketing changelog entry with frontmatter like title, category: "Product", and pull_request. Mention an accompanying image under server/priv/static/marketing/images/changelog/ only when the feature has a visual dashboard/UI state worth showing.

When flagging an inappropriate changelog entry, suggest removing the entry and, if the work still needs coordination, tracking it in the PR description or internal release notes instead.

Do not flag

• Bug fixes with no new or materially changed user-facing behavior.
• Fix PRs, even when the fix includes small user-facing UI changes needed to make an already-shipped flow work correctly.
• Refactors, performance work, infrastructure, ops/admin-only paths, internal jobs, telemetry-only changes, tests, fixtures, or schema-only plumbing whose effect is not directly visible to customers.
• Features gated behind account/org feature flags that are being used for internal rollout or controlled access, unless the PR also makes the feature generally available to customers.
• Documentation-only or marketing-only PRs.
• CLI/app/cache/kura/noora-only changes. This rule is for user-facing server/dashboard features.
• PRs that already add or update a matching server/priv/marketing/changelog/*.md entry.

12. Changeset functions must have tests

Ecto changeset functions in schema modules under server/lib/tuist/ (def changeset/N, def create_changeset/N, def update_changeset/N, or any other *_changeset/N) encode validation and persistence contracts. New or materially changed changeset bodies that ship without tests regress silently: a deleted validate_*, a widened cast list, or a missing unique_constraint won't fail CI — the first signal is a production error or a malformed row.

The convention in this repo is one <schema>_test.exs per schema module that asserts on errors_on(changeset) for invalid inputs and changeset.valid? for valid ones — see server/test/tuist/projects/project_test.exs and server/test/tuist/cache_action_items/cache_action_item_test.exs for canonical examples.

Flag (Severity: medium)

• A new def changeset(, def create_changeset(, def update_changeset(, or any def *_changeset( added in a server/lib/tuist/**/*.ex file whose diff does not also add at least one test case calling that function (e.g. WebhookEndpoint.create_changeset(...), Project.update_changeset(...)) in server/test/tuist/**/*_test.exs.
• A materially changed changeset body — a new or modified cast, validate_required, validate_length, validate_format, validate_inclusion, validate_change, unique_constraint, foreign_key_constraint, or put_change line in the diff — where the change isn't exercised by a test added or modified in the same diff.

When flagging, name the schema module and point to a sibling <schema>_test.exs as the place to add coverage. If no such test file exists, request its creation alongside the changeset.

Do not flag

• Trivial mechanical edits (renaming a field already covered by an existing test, removing a single cast field, formatting-only churn, reordering pipe steps inside an unchanged body).
• Changeset functions in server/test/support/ fixtures or server/priv/repo/seeds*.exs.
• Diffs that exercise the changeset indirectly through a higher-level context test (e.g. accounts_test.exs calling Accounts.create_user/1, which in turn invokes the changeset) — that counts as coverage. Only flag when the diff has no test reference to the schema module or its changeset functions.
• Changeset edits that are purely a consequence of a column rename already covered by a migration-level test or by an existing errors_on(changeset) assertion that still passes against the new field name.

Out of scope (handled elsewhere — do not flag)

• Module / function naming, pipe-chain start, function ordering, parentheses-on-no-arg-calls → mix format + credo (PipeChainStart, StrictModuleLayout, Nesting, UnsafeToAtom, ModuleDoc).
• Inline import / alias / require inside a def/defp/test/ setup/describe body → covered by the custom credo check Credo.Checks.DisallowDirectivesInFunction.
• Missing @spec / @type — this codebase intentionally avoids typespecs. Never suggest adding them.
• Missing @doc / @moduledoc on internal helper modules.
• String.to_atom/1 on user input — credo's UnsafeToAtom covers it.

Before submitting findings

For each finding, confirm:

1. The path:line is real and the snippet appears in the diff.
2. The category above is one of 1–12; if it isn't, downgrade to a question (uncertain: ...) rather than asserting a finding.
3. The severity is set: critical (auth bypass / cross-tenant read or write), high (likely security or correctness bug), medium (compliance / consistency gap), low (nice-to-have).
4. You are not reporting an unchanged line as a finding. Unchanged context can explain a diff finding, but cannot be the finding itself.