Liveview Patterns

What it does

When your agent uses it

• Handling interactions
• Debugging events
• Tracking Presence

Example prompts

• “/liveview-patterns”

Workflow steps

10 steps, taken from the first numbered list in SKILL.md.

1. 1NO UNCONDITIONAL DB QUERIES IN MOUNT — Mount runs TWICE. Default: assign_async. SEO routes: connected? guard + cache-backed disconnected…
2. 2ALWAYS USE STREAMS FOR LISTS — Regular assigns = O(n) memory per user. Streams = O(1)
3. 3CHECK connected?/1 BEFORE SUBSCRIPTIONS — Prevents double subscriptions
4. 4EXTRACT VARIABLES BEFORE assign_async CLOSURE — Closures copy entire referenced variables
5. 5LOAD PRIMARY DATA IN mount/3, PAGINATION IN handle_params/3 — handle_params runs on EVERY URL change
6. 6NEVER PASS SOCKET TO BUSINESS LOGIC — Extract data before calling contexts
7. 7CHECK CHANGESET ERRORS BEFORE UI DEBUGGING — Silent form save = check {:error, changeset} first, not viewport/JS
8. 8HIDDEN INPUTS FOR ALL REQUIRED EMBEDDED FIELDS — Every required field in an embedded schema MUST have a hidden_input if not directly…
9. 9NEVER USE assign_new FOR LIFECYCLE VALUES — assign_new skips the function if key exists. Use assign/3 for locale, current user, or any…
10. 10MATCH {:error, %Ecto.Changeset{}} EXPLICITLY — Bare {:error, _} merges changeset and non-changeset errors; the form silently never…

What it can do on your machine

Read from SKILL.md and the folder at commit 9767a82. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are elixir).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Liveview Patterns loads about 1.3k tokens when it runs, and up to ~8.8k if it reads all its reference files. Until then it costs about 60 tokens; SKILL.md has 404 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~60

When it runs · the whole SKILL.md, loaded when a task matches

~1.3k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~8.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from oliver-kriska/claude-elixir-phoenix at commit 9767a82, republished under its MIT licence (© oliver-kriska). 404 words, ~1,271 tokens.

name

liveview-patterns

description

Build LiveView: async data (assign_async), PubSub (check connected?), phx-change events, form components/modals/uploads, streams for lists, live_patch. Use when handling interactions, debugging events, or tracking Presence.

def mount(%{"slug" => slug}, _session, socket) do
  # Extract needed values BEFORE the closure
  scope = socket.assigns.current_scope

  {:ok,
   socket
   |> assign_async(:org, fn -> {:ok, %{org: fetch_org(scope, slug)}} end)}
end

def mount(_params, _session, socket) do
  {:ok, stream(socket, :items, Items.list_items())}
end

# Insert/update/delete
stream_insert(socket, :items, item, at: 0)
stream_delete(socket, :items, item)

def mount(_params, _session, socket) do
  products =
    if connected?(socket),
      do: Catalog.list_products(),
      else: Cache.get_products() || []

  {:ok, assign(socket, products: products)}
end

def mount(_params, _session, socket) do
  if connected?(socket), do: Chat.subscribe(room_id)
  {:ok, socket}
end

Same LiveView, different params? → patch / push_patch
Different LiveView, same live_session? → navigate / push_navigate
Different live_session or non-LiveView? → href / redirect

Does component need BOTH internal state AND event handling?
│
├── YES → Does it encapsulate APPLICATION logic (not just DOM)?
│   ├── YES → Use LiveComponent ✅
│   └── NO → Refactor to function component with parent handling
│
└── NO → Use Function Component ✅

© oliver-kriska, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 6 other files (references) in targets/pi/skills/liveview-patterns of oliver-kriska/claude-elixir-phoenix.

• SKILL.md
• references/async-streams.md
• references/channels-presence.md
• references/components.md
• references/forms-uploads.md
• references/js-interop.md
• references/pubsub-navigation.md

Open the folder on GitHubat commit 9767a82