maui collectionview-android.instructions.md

Android-specific guidance for the .NET MAUI CollectionView handler, including its RecyclerView adapter, recycled item views, layout manager, memory use, and lifecycle. RecyclerView is Android’s list component that reuses item views while scrolling.

In plain words
What is it for?
Use it when changing CollectionView behavior on Android, including collection updates, item rebinding, view recycling, layout, or cleanup.
Why use it?
It helps keep item updates accurate, preserve scrolling and animations, and avoid stale data or resource leaks in long lists.

Instructions file for GitHub Copilot

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/dotnet/maui/collectionview-android
Clone the repo
git clone --depth 1 https://github.com/dotnet/maui

Made for: GitHub Copilot.

Per session 428 This file is loaded in full into every session.
When invoked 428 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00428 $0.00428
Opus 5 $0.00214 $0.00214
Sonnet 5 $0.00086 $0.00086
Haiku 4.5 $0.00043 $0.00043

Measured yesterday against content hash 70e777d17fd8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

maui collectionview-android.instructions.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.github/instructions/collectionview-android.instructions.md · 33 lines

What it actually says

CollectionView — Android (Items/ Handler)

Items/ is the sole Android handler — see collectionview-handler-detection.instructions.md for the full platform→handler mapping.

RecyclerView Adapter Patterns

  • Use range-specific notifications (NotifyItemRangeInserted, NotifyItemRangeRemoved, NotifyItemRangeChanged) when INCC semantics provide exact affected ranges — prefer these over NotifyDataSetChanged for preserving scroll position and animations
  • Full refresh via NotifyDataSetChanged is valid for Reset actions, ambiguous index cases, and header/footer template changes
  • Handle all ObservableCollection change actions: Add, Remove, Replace, Move, Reset
  • On Reset, recalculate adapter state from scratch — do not assume incremental consistency

ViewHolder Recycling

  • BindingContext MUST be updated on every rebind — stale data from a previous holder is a common source of visual glitches
  • Do not store item-specific state in the ViewHolder outside of BindViewHolder — recycled holders carry state from previous items
  • Dispose and recreate platform views only when the template changes, not on every rebind

Layout Manager

  • Select layout manager (Linear, Grid, custom) based on ItemsLayout specification — do not hardcode
  • ItemsLayout property changes require full layout manager replacement, not partial reconfiguration
  • Account for Android pixel rounding in item measurement — fractional dp values cause 1px gaps

Memory and Lifecycle

  • Unsubscribe from ScrollChange and adapter observers in DisconnectHandler — do NOT call Dispose on platform objects
  • Scroll position restoration after adapter data changes must handle empty-collection edge case

Regression Patterns

  • Test across empty collection, single item, many items, and with grouping — a fix for one layout scenario routinely breaks another
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 33 lines · 428 tokens per session scan A 70e777d17fd8

Subscribe to this mod's changes

maui collectionview-android.instructions.md is an instructions file published in the GitHub repository dotnet/maui (23,317 stars, last pushed yesterday), licensed MIT. It adds 428 tokens to every session, about $0.0021 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.