Operator Surface

The Threadline Operator Surface provides mountable LiveView screens for investigating row mutations, actor histories, and transaction contexts inside your host application.

It is designed to be fully optional: phoenix, phoenix_live_view, phoenix_html, and phoenix_pubsub are optional dependencies, so capture-only integrations aren't forced to bring in UI code.

This guide is the canonical owner for operator capabilities, mounting, authorization, and mount-specific configuration. For every supported application key and command, use the complete configuration and command reference rather than treating examples here as an exhaustive inventory. This guide stays focused on mount, auth, and screens.

For compatibility, support boundaries, and deprecation policy, see the upgrade path. For the broader composition contract across Threadline.Plug, Threadline.Job, reference adapters, and operator-surface auth/export auth, see the integration contracts.

PhoenixStorybook is maintainer-only component documentation in examples/threadline_phoenix and example-app dev/test maintainer tooling, not a root threadline dependency. /audit/__stress remains the authenticated operator-flow stress harness. /audit/__stress is not a production route or public component gallery. /dev/storybook is not a production route and is not part of the mounted /audit operator surface. Adopters do not add phoenix_storybook to host apps to use Threadline. The operator components remain private and are not a public component API.

1-Minute Mount

To enable the UI, first ensure your host app has the root Threadline dependency and the optional Phoenix surface stack that matches your host app. Keep exact Phoenix proof pins in guides/upgrade-path.md; this guide stays on the mount, auth, and screen contract.

def deps do
  [
    # ...
    {:threadline, "~> 0.11.0"}
  ]
end

Then, use the threadline_operator_surface/2 macro in your host application's router. The canonical topology is one host-owned /audit mount behind your browser/auth pipeline, with one shared authorize_fn that works for both the LiveView surface and the export fallback:

defmodule MyAppWeb.Router do
  use MyAppWeb, :router
  import Threadline.OperatorSurface.Router

  pipeline :admin_auth do
    # You MUST provide your own pipeline to authenticate admins.
    plug :require_authenticated_admin
  end

  scope "/audit", MyAppWeb do
    pipe_through [:browser, :admin_auth]

    threadline_operator_surface "/",
      actor_fn: &MyApp.Audit.current_actor/1,
      authorize_fn: &MyApp.Audit.authorize_operator/1,
      schemas: %{
        "posts" => MyApp.Post,
        "users" => MyApp.Accounts.User,
        "support.tickets" => MyApp.Support.Ticket
      },
      repo: MyApp.Repo
  end
end

Keys in schemas: are host table identities from capture; the map is required for row-history and as-of reification in transaction drill-down. A bare "tickets" key is public-schema shorthand. For non-public host schemas or duplicate table names, use schema-qualified keys such as "support.tickets" => MyApp.Support.Ticket. This does not change Threadline's storage schema.

Theme

The operator surface renders in one of three lanes via the optional theme: mount option, validated at compile time to one of :dark | :light | :system (default :dark). That host option selects the default server-rendered lane:

• :dark (default) — the brand-primary surface. Omit theme: entirely to get it; the canonical mount above stays dark with no extra configuration.
• :light — forces the light token lane regardless of the visitor's OS setting.
• :system — auto-follows the visitor's OS preference through scoped CSS only (a @media (prefers-color-scheme: light) lane keyed on the rendered data-tl-theme attribute). It is correct on the first paint / dead render.

Operators can also choose a runtime server-posted dark/light/system theme picker from the shell. The form uses native radio controls with values system, light, and dark, includes a hidden _csrf_token, and submits through the Apply theme button with POST {base_path}/theme. The controller allowlists those values, stores the choice in the session and tl_theme cookie, then redirects back to a same-origin referring operator page. The route is guarded by the same mounted authorize_fn decision as the LiveView pages and requires the host mount to run through a session-backed browser pipeline before session state can be mutated. Subsequent LiveView mounts use the session-backed runtime choice before falling back to the host theme: default, and the active lane renders server-side as data-tl-theme. The tl_theme response cookie mirrors the selected value for the host to inspect; Threadline's mounted LiveViews treat the session value as authoritative.

The picker needs no JavaScript, no localStorage, and no CSP script-src requirement. The only script described later in this guide is the optional copy helper, not the theme picker.

Dark stays the default and the brand; :system is the documented daytime-use recommendation. The light lane is a readability and accessibility choice for teams whose operators work in bright, sunlit rooms and who scan small, dense audit text — a high-legibility need that a dense audit table on a dark surface can work against (a meaningful share of readers, including those with astigmatism, simply read dark-on-light text more comfortably). Choose the lane that fits where your operators actually work:

threadline_operator_surface "/",
  actor_fn: &MyApp.Audit.current_actor/1,
  authorize_fn: &MyApp.Audit.authorize_operator/1,
  schemas: %{"posts" => MyApp.Post, "users" => MyApp.Accounts.User},
  repo: MyApp.Repo,
  theme: :system

Admin-first recipe:

• Keep /audit behind pipe_through [:browser, :admin_auth].
• Return a real Threadline.Semantics.ActorRef from actor_fn; the standard mount path installs Threadline's session bridge and carries that actor into LiveView for saved views and other actor-owned affordances.
• Let authorize_fn make the final allow/deny decision.
• Keep export routes enabled for admins unless your host wants stricter posture.

support-read-only variation:

• Reuse the same /audit surface and the same host auth boundary.
• Return {:ok, %{access: :support_read_only, organization_id: "org_123"}} or another host-owned scope from authorize_fn.
• Use export_authorize_fn to keep export affordances and direct HTTP export requests behind explicit host authorization on the same tree.
• Keep coverage and policy surfaces behind their own explicit coverage_authorize_fn / policy_authorize_fn callbacks; when denied, Threadline renders an unsupported state and points operators to the matching Mix-task fallback.

threadline_operator_surface "/",
  actor_fn: &MyApp.Audit.current_actor/1,
  authorize_fn: &MyApp.Audit.authorize_operator/1,
  export_authorize_fn: &MyApp.Audit.authorize_operator_export/1,
  schemas: %{"posts" => MyApp.Post, "users" => MyApp.Accounts.User},
  repo: MyApp.Repo

Security and Authorization (Fail-Closed Default)

Threadline adopts a fail-closed security posture by default. The threadline_operator_surface/2 macro requires a secure mount. Multi-tenancy and authorization stay host-owned.

Unless explicitly bypassed, the macro will fail at compile time unless one of the following is true:

1. The route scope has at least one pipe_through.
2. The :authorize_fn option is provided.
3. The :adopter_acknowledges_unauthenticated: true option is explicitly supplied (this raises in test and loudly logs a warning in prod).

:authorize_fn

The :authorize_fn callback is invoked directly as a 1-arity function. The recommended shape is one shared callback that pattern-matches on %{assigns: assigns} so the same host-owned policy works for both transports. For the LiveView surface it receives the socket-shaped value passed into Threadline.OperatorSurface.Auth.on_mount/4; when export routes fall back to it, they call it with a synthetic %{assigns: conn.assigns} mirror. The callback should return:

• :ok or true - Allowed.
• {:ok, scope} - Allowed. The scope is host-owned and opaque. Threadline carries it into investigation queries where implemented today, but it does not define a roles DSL, page-level authorization model, or universal scope narrowing contract.
• any other value - Denied.

Telemetry event [:threadline, :operator_surface, :authorize] is emitted with the outcome (:granted, :denied, or :error).

live_session and on_mount protect the LiveView pages only. They do not secure the sibling HTTP export controller routes. Export denials stay HTTP-native through export_authorize_fn: denial or error halts with plain-text 403, not a LiveView redirect.

If you use one shared %{assigns: assigns} export callback, Threadline also uses that result to hide export affordances in the timeline LiveView for denied operator scopes. Direct HTTP export routes remain protected by server/controller auth through the server-side export authorization contract; LiveView hides affordances for denied scopes, but HTTP export auth remains authoritative even if you choose a Conn-specific callback shape and keep the buttons visible.

Coverage and policy views are separate admin/global surfaces. Gate them with coverage_authorize_fn and policy_authorize_fn; denied sessions get an explicit Unsupported View state plus the CLI fallback (mix threadline.health.coverage, mix threadline.policy.show, or the retention Mix path) instead of a silent redirect.

Mounted /audit/evidence is also separately gated. Use evidence_authorize_fn for that capability; denied sessions should get the same explicit Unsupported View posture plus the CLI fallback to mix threadline.evidence.show. Do not describe /audit/evidence as automatically available everywhere the broader /audit surface is mounted. /audit/evidence is a viewer only — host apps write evidence rows via Threadline.Evidence record_*; the mounted surface interprets rows already persisted.

The export-status surface keeps one actor-owned Download Export action. Threadline resolves the actual delivery only after authorization: local storage stays app-served through the controller route, while adapter-backed storage can redirect to a backend-issued URL without exposing that URL in the LiveView HTML.

:actor_fn

The :actor_fn acts just like the native Threadline.Plug configuration, determining the identity performing actions in the operator surface.

On the standard threadline_operator_surface/2 mount path, providing actor_fn installs Threadline's session bridge ahead of the LiveView routes. No extra manual plug is required for the normal mount. Return a real Threadline.Semantics.ActorRef or nil.

Session actor data stays authoritative once LiveView mounts. If your authorize_fn also returns a compatibility-only scope fallback such as %{user_id: ...} or %{actor_ref: ...}, the session actor wins and Threadline emits a low-noise mismatch telemetry event instead of silently inverting ownership.

For a non-standard router or transport shape outside the canonical mount path, compose actor context explicitly before dispatching to the operator router.

Available Screens (v1.17)

The surface provides three must-have workflows out of the box. Together they answer the vast majority of investigation questions on click 1.

Incident Drill-down (/audit/transactions/:id)

Answers: "What exactly changed in this transaction, and why?" Shows all mutations that occurred within a single database transaction, visualizing what was added, removed, or changed. This uses Threadline.incident_bundle/2 under the hood.

Actor Window (/audit/actors/:kind/:id)

Answers: "What did this user/system do recently?" A time-windowed view of all transactions initiated by a specific actor identity. From here, you can deep-link into specific Incident Drill-down screens.

Row History / As-of Sub-view (/audit/rows/:table/:pk)

Answers: "When did this specific record change, and what did it look like at 2:00 PM yesterday?" Reachable directly from drill-down rows, this screen shows the full mutation lifecycle of a single record and reconstructs its exact state as-of any point in time. On the current repo tree, the named support-lane claim now includes support-scoped row-history / as-of proof on the shipped /audit route when the host provides scope_query_fn.

Row history reification (:schemas)

The :schemas option on threadline_operator_surface/2 maps captured table strings to Ecto schema modules so the surface can call Threadline.history/3 and Threadline.as_of/4 for row-history and as-of views. String keys (PostgreSQL table_name values from capture) are preferred; atom keys are also accepted.

Pair :schemas with scope_query_fn when support-scoped row history must respect host tenancy. Pass %{surface: :row_history} from scope_query_fn so narrowed queries apply to history and as-of reconstruction, not just the timeline.

Off-mount API and IEx callers pass the schema module directly to Threadline.history/3 and Threadline.as_of/4; the mount map is the UI equivalent of that registration step.

The guide shorthand /audit/rows/:table/:pk describes the operator question. The shipped drill-down path is a slide-over on the transaction page:

live("/transactions/:id/history/:table/:record_id", TransactionLive, :history)

Support-scoped row history requires two host prerequisites: (1) scope_query_fn that narrows queries (including %{surface: :row_history}), and (2) :schemas with an entry for each reifiable table.

When a table is not mapped, the row-history slide-over shows:

Table 'X' is not mapped to an Ecto schema. Configure :schemas in the auth plug.

Auth and authorization are unaffected; add the missing map entry on threadline_operator_surface/2 and redeploy. The error copy says "auth plug" for historical grep parity with the UI; the option lives on the mount macro, not a separate plug.

First verification steps

After mounting /audit, verify the boundary before you treat the surface as ready:

1. Visit /audit as an allowed admin and confirm the timeline loads.
2. Hit an export URL without the required host auth and confirm you get 403 rather than a redirect loop.
3. Run mix threadline.health.coverage and compare it with /audit/coverage.
4. Run mix threadline.policy.show and compare it with /audit/policy/redaction.

Storage schema vs host schema quick path

Threadline's storage_schema controls where Threadline stores audit tables. The host table schema remains the schema where your application tables live:

config :threadline, storage_schema: "audit"

Install Threadline storage objects, generate capture for a non-public host table, then verify the same host schema across the fallback transports and the mounted Timeline:

mix threadline.install
mix threadline.gen.triggers --tables support.tickets
mix threadline.verify_coverage --schema=support
mix threadline.policy.show --schema=support

Coverage and redaction links into Timeline preserve the host-table identity as table_schema=support&table=tickets, for example:

/audit/timeline?table_schema=support&table=tickets

Mounted workflow parity

mix threadline.incident Companion Task

For operators who rely on SSH or CLI access (and for projects not using Phoenix), Threadline provides parity via a Mix task.

You can query the exact same incident data natively in the terminal without mounting the LiveView surface:

mix threadline.incident <transaction_id>

Coverage and audit readiness

The operator surface ships selected-schema audit readiness at /audit/coverage by wrapping Threadline.Health.trigger_coverage/1. Every LV in the surface also renders a small "uncovered count" pill in its header so operators notice public-schema drift from any screen.

Selected schema readiness

The Coverage page renders one Selected schema readiness verdict before table triage. The verdict names the active schema, last checked time, covered count, Needs capture count, and expected gaps excluded from readiness. A schema is not ready when any table is marked Needs capture. A schema is ready for tracked tables when all tracked rows are covered and only expected gaps remain.

Schema selection

Use the native Schema select on /audit/coverage to switch schemas. The selected schema is encoded in the URL so the view is shareable:

/audit/coverage?schema=tenant_42

The schema is validated at the LV edge (regex + pg_namespace lookup). Invalid input renders a schema-not-found message, keeps the picker usable, and offers Use public schema instead of showing stale rows from another schema.

Refresh and stale data

The page polls every 30 seconds by default. Override globally:

config :threadline, :coverage_poll_ms, 30_000

Floor is 5_000 ms — below this the two pg_* queries become a noisy neighbor on busy schemas.

Manual refresh re-fetches the selected schema. If refresh fails after a prior success, the page keeps the last known results and last checked time, then shows a stale warning so operators do not mistake old counts for a fresh pass.

Row actions and remediation

Covered rows link to Timeline activity. Public-schema links omit table_schema; non-public links include table_schema=NAME&table=TABLE.

Needs capture rows expose Add capture details with the generator command and follow-up verification. After applying trigger migrations, run:

mix threadline.verify_coverage

For non-public schemas, run:

mix threadline.verify_coverage --schema=NAME

Expected gaps are excluded from readiness and do not show Add capture.

Multi-schema adopters

The surface header badge always queries the "public" schema — multi-schema is opt-in on the Coverage page only.

Marking expected-uncovered tables

Adopters typically have bookkeeping tables that are not application data (Oban, application metrics, vendor add-ons). Declare them so the readiness verdict lists them as Expected gap rather than Needs capture:

config :threadline, :health,
  expected_uncovered_tables: ["oban_jobs", "oban_peers", "oban_producers"],
  audit_anyway: []

Validate at boot in your application.ex:

Threadline.Health.Policy.validate!(Application.get_env(:threadline, :health, []))

The :audit_anyway key removes a baseline entry. Use rarely — it overrides the safe default. Example:

config :threadline, :health,
  audit_anyway: ["schema_migrations"]  # very unusual — opts in to auditing migrations

Mix-task parity

Capture-only adopters who do not mount the surface get the same data via:

mix threadline.health.coverage
mix threadline.health.coverage --json
mix threadline.health.coverage --schema=NAME

The Mix task is a viewer (always exits 0). The CI gate is the existing mix threadline.verify_coverage task, which now also accepts --schema=NAME.

Policy redaction drift

The operator surface also ships a read-only redaction drift viewer at /audit/policy/redaction. It reconciles your configured config :threadline, :trigger_capture policy against the deployed trigger SQL that PostgreSQL is actually running.

What it shows

The page groups tables into three operator-safe states:

• Drift detected — configured redaction does not match deployed trigger SQL. Rerun mix threadline.gen.triggers and apply the migration.
• Could not introspect — Threadline could not safely parse the deployed trigger SQL. Treat this as unresolved drift; rerun mix threadline.gen.triggers and do not assume capture is aligned.
• Config matches deployed — configured redaction matches deployed trigger redaction.

Tables are shown alphabetically within each section. Expanding a row shows the exact configured and deployed exclude, mask, and mask placeholder facts for that table.

No sample values

This surface never renders captured sample values. It only shows column names and placeholder metadata, so operators can confirm policy shape without exposing redacted payloads in the UI.

Mix-task parity

Capture-only adopters can inspect the same facts without Phoenix:

mix threadline.policy.show
mix threadline.policy.show --json
mix threadline.policy.show --schema=NAME
mix threadline.policy.show --schema=support

Default output prints one summary line, one aligned TABLE / STATUS / CONFIG / DEPLOYED / HINT table, then extra detail blocks only for Drift detected and Could not introspect. --json exposes the same top-level states as stable machine values:

• drift_detected
• could_not_introspect
• config_matches_deployed

Telemetry

[:threadline, :health, :checked] fires on every successful poll with measurements %{covered, uncovered, expected_uncovered}. The expected_uncovered measurement is additive — old subscribers reading only covered/uncovered keep working unchanged.

Assets and Content-Security-Policy

The operator surface ships with no external asset pipeline and no JavaScript dependencies. Everything it needs is embedded inline by the mounted LiveViews at render time:

• Styles — a single scoped <style> block rendered by the operator shell.
• Fonts — Geist and IBM Plex Mono as @font-face data-URIs embedded at compile time.
• Copy helper — a tiny, dependency-free <script> that powers the "Copy" affordance on correlation and transaction ids. It binds one delegated listener; there is no host LiveSocket hook to register.

This keeps the surface a true drop-in: mount it and the screens render fully styled, with no assets/ build step.

Opt-outs

Both inline embeds can be disabled — for example to satisfy a strict Content-Security-Policy that forbids inline <style> / <script>:

# Use the host's system font stack instead of the embedded webfonts.
config :threadline, operator_surface_embed_fonts: false

# Drop the inline copy-to-clipboard helper. The id "Copy" buttons are then
# hidden; operators select-and-copy the ids natively instead.
config :threadline, operator_surface_embed_scripts: false

CSP guidance

If you enforce a Content-Security-Policy, the embedded assets require:

• style-src 'unsafe-inline' (or a per-response nonce) for the inline styles and @font-face data-URIs.
• font-src data: for the default embedded @font-face data-URI fonts — or set operator_surface_embed_fonts: false and use your app's normal font stack.
• script-src 'unsafe-inline' for the copy helper — or set operator_surface_embed_scripts: false and drop the 'unsafe-inline' script allowance entirely.

The theme picker does not require script-src 'unsafe-inline'; it is a native server-posted form with CSRF, not a client-side storage or scripting feature.

Disabling an embed never breaks a screen: fonts fall back to the system stack, and the copy affordance falls back to native text selection.

[:threadline, :health, :checked, :error] fires on poll failure with metadata %{error: message}; alert on this for sustained drift.

Operational paths

• Investigate a reported change with the incident playbook.
• Measure capture and query cost before tuning.
• Choose evidence-backed indexes for audit workloads.
• Understand the boundary between repository proof and host evidence.
• Review every supported key, adapter seam, and command.