feat(rooms-list): render rooms list with Legend List

[diegolmello]

Proposed changes

Renders the rooms list with Legend List (@legendapp/list 3.4.0) instead of FlatList.

• Row heights come from getFixedItemSize (regular or condensed height, depending on the display mode). Section separators are measured.
• getItemType tells separators and rooms apart.
• Removed the tuning props Legend List doesn't need: initialNumToRender, windowSize, onEndReachedThreshold, getItemLayout.
• Recycling stays off so a row's swipe state can't carry over to another room.

Profiled on an iOS simulator (dev build) with the same scroll each run: 3 flings down, 2 up.

Run	Commits ≥16ms	Time in those commits
FlatList run 1	25	653ms
FlatList run 2	22	560ms
Legend List run 1	12	286ms
Legend List run 2	8	197ms

Average and slowest commit durations didn't change.

Issue(s)

No ticket.

How to test or reproduce

1. Open the rooms list with enough rooms to scroll.
2. Fling down and back up several times.
3. Pull to refresh.
4. Swipe a room row to show its actions, then swipe another row.
5. Open a room, then go back.
6. Search for a room.
7. Switch the display mode to condensed and scroll again.

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments

Checked on an iOS simulator: scrolling, the header row, pull to refresh, swipe actions, opening a room and going back, and search. Not tested on Android yet.

Summary by CodeRabbit

• Improvements
  • Room rows use responsive sizing based on the selected display mode.
  • Separators are handled separately from room rows, and the loading indicator appears at the end of the list.
  • The room list has updated rendering behavior while preserving its visible content, refresh controls, and loading feedback as you browse.

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ℹ️ Recent review info

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Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: e17415cd-9fe1-4cad-8727-fc8e8c19523d

📥 Commits

Reviewing files that changed from the base of the PR and between a0d6c8c and 04846fa.

📒 Files selected for processing (1)

• app/views/RoomsListView/index.tsx

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• GitHub Check: ESLint and Test / run-eslint-and-test
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🔇 Additional comments (1)

app/views/RoomsListView/index.tsx (1)

127-128: LGTM!

Also applies to: 131-142

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Walkthrough

The rooms list replaces React Native’s FlatList with LegendList. A new hook provides fixed sizing for room items and returns no size for separators. The change adds @legendapp/list and removes several FlatList settings.

Changes

Rooms list migration

Layer / File(s)	Summary
LegendList integration and item sizing package.json, app/views/RoomsListView/hooks/useGetFixedItemSize.ts, app/views/RoomsListView/index.tsx	Adds @legendapp/list and replaces FlatList with LegendList. The sizing hook returns the responsive row height for room items and undefined for separators. The list passes its loading footer as an element and removes the previous layout, initial-render, windowing, and end-reached settings.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

Suggested labels: type: chore

Suggested reviewers: otaviostasiak

Merge Risk: ⚪ Minimal · up to 04846

The rooms list now uses LegendList with sizing that matches its rendered rows, while preference changes still refresh items. No material user-facing regression was established; the change is ready for normal merge checks.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 04846

The migration preserves existing room selection, navigation, and access-related checks. No introduced security flaw is demonstrated, but isolation of each room’s interaction state depends on library recycling behavior that has not been verified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• observed — The new rendering dependency consumes room records and display or identity state inside the mobile application. Row interactions continue to reach existing navigation, favorite, read-state, and hide-room operations. This establishes the integration’s exposure, not the library’s complete internal capabilities.

Trust Boundaries and Controls

• inferred — The inspected migration does not demonstrate a new room-data producer, navigation authority, or action-control bypass. Existing RoomItem action gating and the unchanged press callback are the strongest counterevidence to expanded attacker-controlled reachability.

Resilience and Maintainability Implications

• inferred — Room identity isolation depends on the replacement list’s instance lifecycle. Swipe values belong to each Touchable instance, and RoomItem observes its initial item with cleanup on unmount. Stable keys and action resets support isolation, but without verified recycling semantics they do not prove that a mounted instance cannot be reassigned to another room. No actual state transfer or wrong-room action was demonstrated.

Hardening Proposals

• proposed — After confirming the pinned library API, express the required non-recycling behavior explicitly at the integration boundary so room-state isolation does not depend on an implicit default.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely identifies the main change: replacing the rooms list implementation with Legend List.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Warning

Errors were encountered while retrieving linked issues.

Errors (1)

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[github-actions]

iOS Build Available

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[github-actions]

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[diegolmello]

Verified 04846fa on an iOS 27 simulator (iPhone 18 Pro), logged in to a test workspace.

1. Rooms list in Expanded with avatars: each row shows its avatar and last message (0:00).
2. Display preferences → Condensed, back to the list: last-message previews are gone and rows are shorter right away (0:35).
3. Display preferences → Avatars off, back to the list: avatars are gone right away (1:02).
4. Display preferences → Expanded, Avatars on, back to the list: avatars and last messages are back (1:22).
5. Tap legend-list-roomview: legend-list-roomview opens (1:28).
6. Back, tap rn-header-perf: rn-header-perf opens (1:39), back returns to the list (1:47).

Outcome: pass. Rows re-render on every display preference change, and room taps open the tapped room.

04846fa-small.mp4

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