Fix titlebar SF Symbol raster sizing

[austinywang]

Summary

Closes #7073.

Restores the requested square raster frame for AppKit-backed SF Symbols. The regression came from the CmuxSystemSymbolImage migration in d4342fbaec / #6728: titlebar callers still requested the same 12pt icon size, but RenderableSystemSymbol.configuredAppKitImage aspect-fit the configured AppKit image so non-square symbols rendered with a smaller intrinsic image inside the unchanged titlebar chrome.

Reproduction / confirmation

Confirmed from code and history rather than launching local builds, per the no-build/no-local-test constraint:

• v0.64.17 rendered top-left titlebar symbols with Image(systemName: ...).symbolRenderingMode(.monochrome).cmuxSymbolRasterSize(config.iconSize, weight: ...).
• cmuxSymbolRasterSize applied a system font at the requested point size and a fixed square frame.
• Current main uses CmuxSystemSymbolImage(systemName: ..., pointSize: config.iconSize, weight: ...).
• The AppKit path configured the symbol at the requested point size, then changed NSImage.size through fittedSymbolSize(..., maximumDimension: rasterSize), shrinking the intrinsic image for non-square symbols while the titlebar button/frame metrics stayed unchanged.

Observed from the code path: requested titlebar metrics remained 20pt buttons / 12pt icons, but the rendered image size was reduced for non-square symbols. Expected: AppKit-backed symbol rendering should preserve the requested square raster frame so the visible chrome matches the pre-regression sizing behavior.

Fix boundary

The fix belongs in RenderableSystemSymbol, not the titlebar callsite. The titlebar already passes the correct metric; the abstraction changed the meaning of pointSize when it aspect-fit the configured AppKit image. Keeping the AppKit image creation/cache preserves the macOS 27 crash fix, while removing the extra shrink restores the old cmuxSymbolRasterSize sizing contract for all callers that ask for a concrete symbol point size. Global font magnification remains opt-in through the existing appliesGlobalFontMagnification path.

Tests

• Added a focused regression assertion in RenderableSystemSymbolTests that a non-square AppKit symbol keeps the requested square raster frame.
• First commit is test-only and should fail against the previous aspect-fit behavior; second commit applies the fix.
• Local tests/builds were not run, per instruction. CI is the validation path.

Localization

No user-facing strings changed, so no localization catalog updates were needed.

---

Summary by cubic

Fix titlebar SF Symbol sizing by removing extra aspect-fit scaling for AppKit images so non-square symbols render at their configured size and aspect ratio, restoring the pre-migration look. Closes #7073.

• Bug Fixes
  • Stop downscaling AppKit symbols to a square raster; keep the configured dimensions and aspect ratio, with a square fallback only when the configured size is invalid.

^{Written for commit 2dac51a. Summary will update on new commits.}

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Project	Deployment	Actions	Updated (UTC)
cmux	Canceled		Jun 30, 2026 2:39am
cmux-staging	Building	Preview, Comment	Jun 30, 2026 2:39am

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📥 Commits

Reviewing files that changed from the base of the PR and between 6011d04 and 2105c8c.

📒 Files selected for processing (2)

• Sources/RenderableSystemSymbol.swift
• cmuxTests/RenderableSystemSymbolTests.swift

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue-7073-titlebar-icon-size

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[greptile-apps]

Greptile Summary

Fixes a sizing regression introduced by the CmuxSystemSymbolImage migration: non-square SF Symbols in the titlebar were being aspect-fit down to a smaller intrinsic size by fittedSymbolSize, causing them to appear too small inside the unchanged 16×16 layout frame.

• Bug fix in RenderableSystemSymbol.configuredAppKitImage: replaces fittedSymbolSize (which scaled the longer dimension to rasterSize) with symbolImageSize, which returns AppKit's natural configured size directly and only falls back to a square at rasterSize for invalid/zero input.
• Test update: renames and rewrites the regression test to verify that a non-square symbol (arrow.left.and.right) preserves AppKit's configured size rather than being scaled down; unit test for the helper function is updated to match the new pass-through semantics.

Confidence Score: 5/5

Safe to merge — the change is a well-scoped, one-line fix in a non-concurrent image-sizing helper, and the test target explicitly validates the before/after behavior on a known non-square symbol.

The logic change is minimal and easy to reason about: one aspect-fit computation is replaced with a direct size pass-through, keeping the existing guard for degenerate inputs. The helper function is pure and isolated; the cache layer, actor isolation, and fallback path are all untouched. The regression test added in the same PR directly exercises the corrected code path and would have failed against the previous behavior, giving clear CI coverage for the invariant being restored.

No files require special attention.

Important Files Changed

Filename	Overview
Sources/RenderableSystemSymbol.swift	Replaces aspect-fit sizing (fittedSymbolSize) with a pass-through helper (symbolImageSize) that returns AppKit's natural configured size; invalid/zero sizes still fall back to a square at rasterSize.
cmuxTests/RenderableSystemSymbolTests.swift	Updates unit tests to match the new symbolImageSize contract; adds a focused regression test confirming a non-square symbol preserves AppKit's configured size rather than being scaled down.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["configuredAppKitImage(systemName:pointSize:weight:)"] --> B["clampedRasterPointSize(pointSize) → rasterSize"]
    B --> C{Cache hit?}
    C -- Yes --> D["return cached NSImage"]
    C -- No --> E["NSImage(systemSymbolName:)"]
    E --> F["SymbolConfiguration(pointSize: rasterSize, weight:)"]
    F --> G["baseImage.withSymbolConfiguration(configuration)"]
    G --> H["symbolImageSize(configuredImage.size, fallbackDimension: rasterSize)"]
    H --> I{naturalSize valid?}
    I -- "width/height > 0 and finite" --> J["return naturalSize (AppKit's configured size)"]
    I -- "invalid / zero / NaN" --> K["return NSSize(fallbackDimension × fallbackDimension)"]
    J --> L["image.size = result"]
    K --> L
    L --> M["cache & return image"]

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
    A["configuredAppKitImage(systemName:pointSize:weight:)"] --> B["clampedRasterPointSize(pointSize) → rasterSize"]
    B --> C{Cache hit?}
    C -- Yes --> D["return cached NSImage"]
    C -- No --> E["NSImage(systemSymbolName:)"]
    E --> F["SymbolConfiguration(pointSize: rasterSize, weight:)"]
    F --> G["baseImage.withSymbolConfiguration(configuration)"]
    G --> H["symbolImageSize(configuredImage.size, fallbackDimension: rasterSize)"]
    H --> I{naturalSize valid?}
    I -- "width/height > 0 and finite" --> J["return naturalSize (AppKit's configured size)"]
    I -- "invalid / zero / NaN" --> K["return NSSize(fallbackDimension × fallbackDimension)"]
    J --> L["image.size = result"]
    K --> L
    L --> M["cache & return image"]

Loading

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