For a PHAsset in the same Photos library on the same device/Mac, what are the documented stability guarantees of PHObject.localIdentifier? Is it safe to persist and use for future PhotoKit operations in that same local library? Are there known cases where it can change or stop resolving? If a persisted localIdentifier no longer resolves but a persisted PHCloudIdentifier.archivalStringValue does resolve in the same library, is updating the stored local identifier from that cloud mapping the recommended recovery path? Thanks!

Is the memoryLimit option mentioned in WWDC26 session 305 the same option as CIContextOption.memoryTarget? The session says the default memory target on iOS is 256 MB. What is the default memoryTarget on macOS? Also, the session recommends the Extended Virtual Addressing entitlement for interactive RAW editing. That entitlement does not appear to be available for macOS, so does Core Image automatically use a larger intermediate cache budget on macOS? Should memoryTarget be used only for export contexts, or can/should it also be tuned for interactive editing contexts with cacheIntermediates enabled? Thanks!

I render images using a tiled/LOD pipeline. The final render usually requests only the visible ROI at the current display scale, which works well for local filters. The difficult case is filters that need a lower-resolution full-extent or larger-extent input, such as guided filters, blurs, histograms/statistics, and reduce passes. If that dependency remains inside the same CI graph, ROI propagation can force larger-extent evaluation of the upstream image, defeating small-ROI rendering. My current approach is to render those intermediates in a separate lower-resolution CI render pass, cache the result, and feed the rendered intermediate back into the final graph. Is this the recommended architecture, or is there a better Core Image structure for expressing this kind of intermediate render/cache barrier without manually creating and rendering a separate intermediate graph? Thanks!

Could you provide a more detailed description of how isHighlightRecoveryEnabled affects the image, and how it differs from isGamutMappingEnabled? I’d like to explain these controls accurately to my users. Does highlight recovery run before or after linearSpaceFilter, and should it be disabled when generating scene-referred linear output? Thanks!

In WWDC20 it was mentioned that missing compileTime/renderTime (or no intermediate image with the dump-intermediates option) can indicate a cached intermediate. I have also seen renderTime=cacheHit on passes that are clearly rendering intermediates, and an actual renderTime is only properly shown on the final pass which always seems to equal the final time render time. In compileTime it says cacheMiss. Which fields should be considered authoritative for tracking intermediate cache hits versus actual rendering? Thanks!

In my testing, enabling isDraftModeEnabled improves decode performance for very large non-RAW images. Does it also affect decoding performance or quality for RAW images? Are there non-RAW formats that benefit more than others, or not at all, with draft mode? For non-RAW images, is it generally recommended to load them through CIRAWFilter or CIImage? If CIImage is preferred, is there an equivalent to isDraftModeEnabled for CIImage initialization? Conversely, if CIRAWFilter is acceptable for non-RAW images, how can I get the expandToHDR behavior that is available through CIImage options? Thanks!

I’m really excited about RAW 9, great work! Since RAW 9 is not enabled by default, are there any recommended use cases where it makes sense to select it by default, if supported? For compatibility handling, should I treat decoderVersion as covering all processing and adjustments performed by CIRAWFilter, or does it mostly affect the RAW decoding stage? When switching decoder versions, should I re-evaluate which CIRAWFilter adjustments are supported? Also, the macOS 26 headers appear to expose version9 and version9DNG. Is RAW 9 actually supported on macOS 26 runtimes? Thanks!

CIRAWFilter documentation lists despeckleAmount as available on macOS 12.0+, but I cannot find this property in the macOS 26 headers. Could you provide a detailed description of how despeckleAmount affects the image so I can explain this adjustment accurately to my users? Does it run before or after linearSpaceFilter, and what should it be set to when generating scene-referred linear output? Thanks!

What is the intended purpose of the new PHPhotoLibraryPersistentChangesObserver? I currently use PHPhotoLibraryChangeObserver as a trigger, then call fetchPersistentChanges(since:). What behavior or guarantees differ when using PHPhotoLibraryPersistentChangesObserver instead? Thanks!

Is there a supported way for developers to purge locally downloaded Photos originals/resources in order to force an asset/resource into a non-downloaded iCloud-only state? Basically simulate "Optimize Mac Storage" behavior on demand for testing. Thanks!

Is there a way to determine whether a specific PHAssetResource original is locally available/downloaded without requesting it? If not, is the recommended approach to request the resource with PHAssetResourceRequestOptions.isNetworkAccessAllowed = false and handle networkAccessRequired error? Is that error the definitive signal that the requested resource is not locally available, or are there other errors that should be treated the same way? Thanks!

PHAsset.mediaSubtypes.contains(.photoDepthEffect) exposes the portrait/depth-effect flag through PhotoKit. Is there a way to detect the same Photos “Portrait” classification when reading the image file directly using ImageIO? I've found that key 25 in kCGImagePropertyMakerAppleDictionary appears to correlate with the Portrait flag. Is the existence of this key a stable signal for that classification, or should I use another ImageIO signal? Thanks!

What is the recommended way to determine whether an item can be moved to Finder Trash on a given volume? If no Trash directory is available, is user confirmation followed by immediate deletion the expected path? For which common volume types is a Trash directory unavailable? Thanks!

What is URLResourceKey.documentIdentifierKey intended to identify compared with fileIdentifierKey? Is it expected to persist across save/replace operations, rename, move, app relaunch, or unmount/remount? Thanks!

In my sandboxed app, if a bookmarked network source is unavailable, is resolving the source/root security-scoped bookmark the recommended way to way to trigger a remount of the network volume? Thanks!