perf(cmux-tui): avoid cloning projection specs per frame by lawrencecchen · Pull Request #11487 · manaflow-ai/cmux

lawrencecchen · 2026-09-01T19:35:39Z

Summary

extract the SidebarResourceKind leaf before mutable projection rendering
preserve empty-projection and missing-view behavior
add a behavior test for the configured leaf label

This replaces #11485 under the matching opener and commit-author identity. The source head is unchanged. The scalar extraction removes per-frame SidebarViewSpec heap copies without changing row order, selection, hit targets, or labels.

Verification

rustfmt --edition 2024 --check
git diff --check
exact hosted Linux, macOS, MSRV, and aarch64 proof: https://github.com/manaflow-ai/cmux/actions/runs/33546180678
exact stable Codex 0.151, gpt-5.6-sol, high review: clean, correctness 0.98

Summary by cubic

Avoids cloning the projection spec on every frame, cutting per-frame heap allocations in the sidebar without changing row order, selection, hit targets, or labels.

Derives the empty-projection resource label from a borrowed view spec instead of a cloned one.
Adds a regression test that ensures an empty projection uses its configured leaf resource label.

^{Written for commit 52eba4a. Summary will update on new commits.}

Summary by CodeRabbit

Bug Fixes
- Empty sidebar views now display the correct message for the configured resource, such as “no tabs,” instead of incorrectly referring to workspaces.
Tests
- Added coverage to verify empty-state messaging when a sidebar view is configured with multiple levels.

github-actions · 2026-09-01T19:36:00Z

All contributors have signed the CLA ✍️ ✅
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coderabbitai · 2026-09-01T19:36:45Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Team

Run ID: a1bb1e15-1e96-4a63-8d3b-7f2ae5447c94

📥 Commits

Reviewing files that changed from the base of the PR and between 2ead477 and b357092.

📒 Files selected for processing (2)

cmux-tui/crates/cmux-tui/src/app.rs
cmux-tui/crates/cmux-tui/src/ui/sidebar.rs

Included review availability: Your plan provides up to 10 included reviews per hour; 1 remains after this review.

📝 Walkthrough

Walkthrough

Changes

Sidebar empty-state rendering

Layer / File(s)	Summary
Resolve leaf resource labels and validate rendering `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`, `cmux-tui/crates/cmux-tui/src/app.rs`	`draw_projection` uses the final configured resource kind for empty-state text without cloning the full view specification. The test verifies that a `workspace-tabs` projection renders `"no tabs"` and not `"no workspaces"`.

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

Merge Risk: ⚪ Minimal · up to b3570

The change removes per-frame projection-spec cloning while preserving sidebar labels and behavior; no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 15

✅ Passed checks (15 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: avoiding per-frame cloning of projection specifications in cmux-tui.
Description check	✅ Passed	The description clearly explains what changed, why it changed, behavior preservation, the added regression test, and verification performed. It is mostly complete, although it does not include the tem…
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 …
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.
Cmux Swift Actor Isolation	✅ Passed	PASS. The pull-request diff contains only two Rust files: `cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`. It contains no Swift paths or Swift diff content. Ther…
Cmux Swift Blocking Runtime	✅ Passed	PASS. The PR diff contains only `cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`, both Rust files. It adds a Rust test and changes Rust rendering code. It introdu…
Cmux Browser Automation Off-Main	✅ Passed	PASS: The PR diff contains only `cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`. The changes add a Rust TUI test and change sidebar projection rendering. They do…
Cmux Expensive Synchronous Load	✅ Passed	PASS: The complete pull-request diff from merge base `2ead47750` changes only `cmux-tui` Rust files (`app.rs` and `ui/sidebar.rs`). It adds a Rust test and changes sidebar projection rendering. No Swi…
Cmux Cache Substitution Correctness	✅ Passed	PASS: The pull request changes only Rust files (`cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`). The custom check applies only to production Swift, TypeScript, …
Cmux No Hacky Sleeps	✅ Passed	PASS. The pull request changes only Rust files: `cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`. The production change extracts a sidebar resource value and adds…
Cmux Algorithmic Complexity	✅ Passed	PASS: The PR changes only Rust files (`cmux-tui/.../app.rs` and `ui/sidebar.rs`), so the stated Swift/TypeScript/JavaScript/shell scope does not identify a failure. The production change replaces a fu…
Cmux Swift Concurrency	✅ Passed	PASS. The exact diff against `origin/main` changes only `cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`, both Rust files. It adds a Rust test and changes Rust si…
Cmux Swift `@Concurrent`	✅ Passed	PASS. The pull-request diff from `origin/main` changes only `cmux-tui/crates/cmux-tui/src/app.rs` and `cmux-tui/crates/cmux-tui/src/ui/sidebar.rs`. It contains no Swift files or Swift concurrency anno…
Cmux Swift Package Boundaries	✅ Passed	PASS: The PR diff contains only two Rust files under `cmux-tui` (`app.rs` and `ui/sidebar.rs`). It introduces no production Swift changes and does not alter a SwiftPM package boundary. The Swift packa…

Full details: Description check

Explanation

The description clearly explains what changed, why it changed, behavior preservation, the added regression test, and verification performed. It is mostly complete, although it does not include the template's Demo Video, Review Trigger, or Checklist sections.

Full details: Docstring Coverage

Explanation

Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 too large.)

Full details: Cmux Swift Actor Isolation

Explanation

PASS. The pull-request diff contains only two Rust files: cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs. It contains no Swift paths or Swift diff content. Therefore, it cannot introduce or worsen the specified Swift 6 actor-isolation issues.

Full details: Cmux Swift Blocking Runtime

Explanation

PASS. The PR diff contains only cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs, both Rust files. It adds a Rust test and changes Rust rendering code. It introduces no production Swift changes and no Swift blocking or timing primitive covered by the check.

Full details: Cmux Browser Automation Off-Main

Explanation

PASS: The PR diff contains only cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs. The changes add a Rust TUI test and change sidebar projection rendering. They do not modify browser socket commands, WebKit/AppKit routing, processV2Command, socketWorkerMethods, or policy tests. The browser automation check is therefore not applicable.

Full details: Cmux Expensive Synchronous Load

Explanation

PASS: The complete pull-request diff from merge base 2ead47750 changes only cmux-tui Rust files (app.rs and ui/sidebar.rs). It adds a Rust test and changes sidebar projection rendering. No Swift or Objective-C production files changed, and no prohibited agent-history load symbols or paths appear in the changed files. Therefore this Swift-specific synchronous-load check is not applicable.

Full details: Cmux Cache Substitution Correctness

Explanation

PASS: The pull request changes only Rust files (cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs). The custom check applies only to production Swift, TypeScript, and JavaScript changes. The diff does not replace an authoritative persistence, history, undo, or snapshot read in any covered language.

Full details: Cmux No Hacky Sleeps

Explanation

PASS. The pull request changes only Rust files: cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs. The production change extracts a sidebar resource value and adds no sleep, timer, polling, delay, or wall-clock wait. The added test uses deterministic rendering only. The rule applies to TypeScript, JavaScript, shell, and non-Swift build/runtime scripts, so it is not applicable here.

Full details: Cmux Algorithmic Complexity

Explanation

PASS: The PR changes only Rust files (cmux-tui/.../app.rs and ui/sidebar.rs), so the stated Swift/TypeScript/JavaScript/shell scope does not identify a failure. The production change replaces a full SidebarViewSpec clone with one .last() lookup before rendering. It adds no nested collection scan, repeated sorting/filtering, batch rescan, join, or slower algorithm. The added collection setup and assertions are test-only.

Full details: Cmux Swift Concurrency

Explanation

PASS. The exact diff against origin/main changes only cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs, both Rust files. It adds a Rust test and changes Rust sidebar rendering. No cmux-owned Swift code or listed Swift concurrency pattern changed.

Full details: Cmux Swift `@Concurrent`

Explanation

PASS. The pull-request diff from origin/main changes only cmux-tui/crates/cmux-tui/src/app.rs and cmux-tui/crates/cmux-tui/src/ui/sidebar.rs. It contains no Swift files or Swift concurrency annotations, so the @concurrent check is not applicable.

Full details: Cmux Swift Package Boundaries

Explanation

PASS: The PR diff contains only two Rust files under cmux-tui (app.rs and ui/sidebar.rs). It introduces no production Swift changes and does not alter a SwiftPM package boundary. The Swift package boundary check is therefore inapplicable.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

Create stacked PR
Commit on current branch

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch fix/sidebar-empty-resource-wave201

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cursor · 2026-09-01T19:42:33Z

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vercel · 2026-09-01T19:42:33Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
cmux166	Ready	Preview	Sep 2, 2026 3:10am UTC
cmux41	Ready	Preview	Sep 2, 2026 3:10am UTC

6044a8b docs(tui): align frontend protocol references (manaflow-ai#10246) 56457e4 perf(cmux-tui): avoid cloning projection specs per frame (manaflow-ai#11487) 9503718 ci: guard focused filters that match only ignored tests

lawrencecchen mentioned this pull request Sep 1, 2026

perf(cmux-tui): avoid cloning projection specs per frame #11485

Closed

lawrencecchen added 2 commits September 1, 2026 12:42

test(cmux-tui): cover empty projection leaf label

0475bf8

perf(cmux-tui): borrow projection leaf resource

52eba4a

lawrencecchen force-pushed the fix/sidebar-empty-resource-wave201 branch from b357092 to 52eba4a Compare September 1, 2026 19:42

lawrencecchen merged commit 56457e4 into main Sep 1, 2026
38 of 40 checks passed

lawrencecchen deleted the fix/sidebar-empty-resource-wave201 branch September 1, 2026 19:56

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perf(cmux-tui): avoid cloning projection specs per frame - #11487

perf(cmux-tui): avoid cloning projection specs per frame#11487
lawrencecchen merged 2 commits into
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fix/sidebar-empty-resource-wave201

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