Fix degraded SF Symbol rasterization after #10549 by austinywang · Pull Request #10591 · manaflow-ai/cmux

austinywang · 2026-08-22T23:47:16Z

Summary

NSGraphicsContext(bitmapImageRep:) captures the bitmap representation's point-to-pixel transform when it is created. The materializer in #10549 created that context while the bitmap still reported its pixel dimensions, then assigned the logical point size afterward. The symbol was therefore rasterized at 1x into the upper-left portion of a 2x bitmap and displayed soft, thin, and displaced.

This change reapplies the eager materialization and titlebar prewarming from #10549 on top of the merged revert, but assigns each bitmap's point-space size before creating its context. The context CTM now maps the configured symbol rect across the full backing bitmap. Each returned image carries owned 1x and 2x bitmap representations, allowing AppKit to choose a native scale without resampling. The template flag remains true, preserving AppKit tinting and enabled/disabled appearance behavior.

Regression coverage

The first commit adds a pixel-level regression test that draws the returned image and a fresh configured AppKit symbol into independently initialized bitmaps.
The test runs at both 1x and 2x and compares alpha-weighted centroid, bounding box, and coverage, so the pre-fix scale/placement regression fails.
The eager-materialization test verifies both representations are bitmap-backed and that no lazy symbol provider is returned.
The test-only regression commit precedes the fix commit intentionally.

This supersedes the stopgap revert #10584: it keeps #10547 fixed while restoring crisp titlebar icon rendering.

Validation

xcrun swiftc -parse passed for all changed Swift files.
./scripts/lint-pbxproj-test-wiring.sh passed.
./scripts/check-pbxproj.sh passed.
python3 scripts/check-package-resolved-policy.py passed.
No local Xcode build or test was run, per task instructions; hosted CI is the test environment.

Closes #10586

coderabbitai · 2026-08-22T23:49:02Z

📝 Walkthrough

Walkthrough

materializedImage now sets bitmap size before graphics context creation. Tests compare the materialized plus symbol with direct AppKit rendering at 2× using pixel size, centroid, bounds, and alpha coverage.

Changes

SF Symbol rasterization

Layer / File(s)	Summary
Correct bitmap context setup `Sources/RenderableSystemSymbol.swift`	`materializedImage` assigns the bitmap’s point-space size before creating `NSGraphicsContext`.
Validate rasterized pixel geometry `cmuxTests/RenderableSystemSymbolTests.swift`	Tests analyze alpha pixels and compare materialized and direct AppKit rendering for the `plus` symbol at 2×.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🔵 Low · up to df260

The fix restores crisp SF Symbol rendering by correcting the bitmap transform before rasterization, but the regression test currently covers only 2x backing scale, so a 1x-only rendering issue could go unnoticed. The PR is mergeable with explicit owner awareness or follow-up to add 1x coverage.

🚥 Pre-merge checks | ✅ 24 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The implementation fixes the context-ordering defect and preserves eager bitmap materialization and template tinting, but regression coverage only verifies 2x rendering.	Add regression coverage for both 1x and 2x backing scales, as required by issue `#10586`.

✅ Passed checks (24 passed)

Check name	Status	Explanation
Out of Scope Changes check	✅ Passed	The source and test changes directly support the linked issue by fixing rasterization and adding targeted regression coverage.
Docstring Coverage	✅ Passed	Docstring check was indeterminate for this PR — some files could not be analyzed in time. Not blocking.
Cmux Swift Actor Isolation	✅ Passed	The production diff only reorders bitmap setup and adds comments; all actor annotations and Sendable/model declarations are unchanged. New raster tests are explicitly `@MainActor`.
Cmux Swift Blocking Runtime	✅ Passed	The two-commit diff only reorders bitmap/context setup in production and adds deterministic bitmap test code; it introduces no semaphore, wait, sleep, timer, polling, sync, or lock primitive.
Cmux Browser Automation Off-Main	✅ Passed	The PR changes only SF Symbol rasterization and its tests; no browser.* socket command, worker routing, WebKit wait, or policy-test change is present.
Cmux Expensive Synchronous Load	✅ Passed	The PR diff only reorders bitmap sizing and graphics-context creation, plus a raster test; it adds no agent-history load, directory scan, transcript parse, or synchronous large-file operation.
Cmux Cache Substitution Correctness	✅ Passed	The PR only reorders NSBitmapImageRep setup and adds raster tests; cache declarations and uses are unchanged, with no authoritative-read substitution or persistence/history/undo/snapshot path affec...
Cmux No Hacky Sleeps	✅ Passed	The PR changes only Sources/.swift and cmuxTests/.swift; no non-Swift runtime files or added fixed sleeps, timers, polling, or wall-clock waits appear in the diff.
Cmux Algorithmic Complexity	✅ Passed	The production diff only reorders bitmap setup and adds a guard. The only nested scan is pixel analysis in test code, explicitly exempt by the rule.
Cmux Swift Concurrency	✅ Passed	The PR diff only reorders bitmap setup and adds synchronous XCTest raster checks; it introduces no Dispatch queues, Combine state, completion handlers, or fire-and-forget Tasks.
Cmux Swift `@Concurrent`	✅ Passed	The two-commit diff adds no async, nonisolated, or `@concurrent` code. Changed materializedImage remains synchronous `@MainActor` work, so no stated annotation or async UI-hop failure applies.
Cmux Swift Package Boundaries	✅ Passed	The PR only reorders bitmap setup in a private `@MainActor` AppKit rasterization bridge; the 119-line pixel analyzer is test code, so no reusable package logic is introduced or expanded.
Cmux Swiftpm Lockfiles	✅ Passed	The two-commit PR diff changes only Sources/RenderableSystemSymbol.swift and cmuxTests/RenderableSystemSymbolTests.swift; no Package.swift, Package.resolved, Xcode project, .gitignore, workflow, or...
Cmux Swift Logging	✅ Passed	The PR changes only bitmap setup and test raster analysis; added Swift lines contain no print, debugPrint, dump, NSLog, Logger, or ad hoc logging.
Cmux User-Facing Error Privacy	✅ Passed	The diff changes bitmap rendering and adds tests only; it adds no user-facing errors or sensitive diagnostics. AppKit/provider wording appears only in developer comments and tests, which the rule a...
Cmux Full Internationalization	✅ Passed	The production diff only reorders bitmap setup and adds developer comments; all new user-visible text is test code, which the rule explicitly allows.
Cmux Swiftui State Layout	✅ Passed	The PR only changes AppKit bitmap ordering and adds raster tests; the existing SwiftUI bridge view is unchanged, with no new state, GeometryReader, lazy rows, or render-time mutation.
Cmux Architecture Rethink	✅ Passed	The merge-base diff only reorders bitmap.size before NSGraphicsContext creation and adds pixel tests; it introduces no timing, blocking, observer, side-channel, or lifecycle-owner workaround.
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	The diff changes only bitmap symbol rasterization and test helpers; it adds no standalone window code, and lint_auxiliary_window_close_shortcuts.py passes.
Cmux Source Artifacts	✅ Passed	The PR changes only Sources/RenderableSystemSymbol.swift and cmuxTests/RenderableSystemSymbolTests.swift; both contain intentional hand-written source/test code, with no artifact-like paths.
Cmux No Test Or Debug Seam In Production Source	✅ Passed	The PR adds no test/debug seam to Sources; its production diff only reorders bitmap context setup, and resetRenderabilityCacheForTesting already existed at the merge base.
Cmux No Ambient Global State	✅ Passed	The production diff only reorders bitmap setup inside existing private RenderableSystemSymbol.materializedImage; it adds no global function, mutable global, namespace type, or singleton.
Title check	✅ Passed	The title clearly identifies the primary change: fixing degraded SF Symbol rasterization.
Description check	✅ Passed	The description explains the cause, implementation, regression coverage, validation, and issue linkage, but omits the template checklist and demo video.

✨ Finishing Touches 💡 1

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Resolve merge conflict in branch issue-10586-symbol-raster-scale

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch issue-10586-symbol-raster-scale

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greptile-apps · 2026-08-22T23:49:07Z

Greptile Summary

The PR eagerly materializes configured SF Symbols into correctly scaled 1x and 2x bitmap representations before titlebar layout, preserving template rendering and adding pixel-level regression coverage.

Sets each bitmap’s logical point size before constructing its graphics context.
Prewarms the bounded set of titlebar symbol configurations during accessory startup.
Routes additional titlebar controls through the materialized-symbol component.
Tests eager materialization and raster geometry at both supported backing scales.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
Sources/RenderableSystemSymbol.swift	Materializes configured symbols into correctly transformed 1x and 2x bitmap representations while retaining the template-image contract.
Sources/Update/TitlebarCloudVMButton.swift	Routes plus, cloud, and dropdown glyphs through the shared materialized-symbol view.
Sources/Update/UpdateTitlebarAccessory.swift	Prewarms the finite set of titlebar symbol configurations before attaching accessories to windows.
cmuxTests/RenderableSystemSymbolTests.swift	Adds eager-representation and pixel-geometry regression coverage at 1x and 2x backing scales.

_{Reviews (3): Last reviewed commit: "fix: preserve SF Symbol raster scale" | Re-trigger Greptile}

coderabbitai

Actionable comments posted: 1

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Inline comments:
In `@cmuxTests/RenderableSystemSymbolTests.swift`:
- Around line 117-148: Update renderedBitmap and the configuredAppKitImage
geometry test to accept and use a pixelScale parameter, then run the same
footprint comparisons at both 1x and 2x. Preserve the existing
direct-versus-materialized image assertions and apply the scale-specific bitmap
rendering consistently for each tested backing scale.

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ℹ️ Review info

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Review profile: ASSERTIVE

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Run ID: d0c908a7-cf81-40ae-b361-ad55744e8282

📥 Commits

Reviewing files that changed from the base of the PR and between 456e425 and df260b2.

📒 Files selected for processing (2)

Sources/RenderableSystemSymbol.swift
cmuxTests/RenderableSystemSymbolTests.swift

Included review availability: Your plan provides up to 10 included reviews per hour; 0 remain after this review.

austinywang · 2026-08-23T00:02:16Z

Addressed the review feedback in 97bf365:

The raster-geometry test now runs the same centroid, bounds, and alpha-coverage assertions at both 1x and 2x.
The materialized image now contains native 1x and 2x bitmap reps, so neither scale is produced by resampling the other.
The branch has been rebased onto the merged revert on origin/main; gh pr view reports mergeable CLEAN.

austinywang · 2026-08-23T00:32:41Z

Hosted validation note: the focused cmuxTests/RenderableSystemSymbolTests lane was attempted on both Warp (run https://github.com/manaflow-ai/cmux/actions/runs/32606603970) and Blacksmith macOS 15 (run https://github.com/manaflow-ai/cmux/actions/runs/32607449481). The changed source compiled, but the shared cmux-unit test bundle failed before executing tests with the existing undefined CMUXAuthCore/CmuxAuthRuntime linker symbols (the same failure appears in prior main test-depot runs, e.g. https://github.com/manaflow-ai/cmux/actions/runs/32546133025). No symbol-raster test failure or new warning was reported; the PR’s required checks remain green and mergeability is CLEAN.

test: compare SF Symbol raster geometry

e6ad6bf

coderabbitai Bot reviewed Aug 22, 2026

View reviewed changes

Comment thread cmuxTests/RenderableSystemSymbolTests.swift Outdated

austinywang force-pushed the issue-10586-symbol-raster-scale branch from df260b2 to 7835552 Compare August 22, 2026 23:52

fix: preserve SF Symbol raster scale

97bf365

austinywang force-pushed the issue-10586-symbol-raster-scale branch from 7835552 to 97bf365 Compare August 22, 2026 23:57

austinywang merged commit 152a7ac into main Aug 23, 2026
8 of 10 checks passed

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Fix degraded SF Symbol rasterization after #10549 - #10591

Fix degraded SF Symbol rasterization after #10549#10591
austinywang merged 2 commits into
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issue-10586-symbol-raster-scale

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Confidence Score: 5/5

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