[Feature]: adopt general-purpose helpers that two first-party games keep re-writing

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What this is

DoxReloaded holds utility code that is not about DoxReloaded. We scanned the game for it. This issue lists what we found, ranked.

Every candidate below passes two tests. Its parameters and return use only primitives, System.* or UnityEngine.*. No game type appears. We also searched this package first, and we say what we searched.

Package read at 3.5.0. We propose the API. We do not ask you to take our code.

Ranked candidates

#	Proposed API	Evidence	Searched
1	DurableFile.TryWriteAllText/TryWriteAllBytes/WriteAllTextAsync/TryDelete	A second first-party game already has a hand copy. The DoxReloaded file says so in its own doc comment: "Ported from the sibling IshoBoy project's DurableFile". Writes a sibling .tmp, flushes to disk, then swaps, so a broken write cannot truncate the live file	Core/Helper/FileHelper.cs has InitializePath and CopyFileAsync only. PathHelper, DirectoryHelper are path resolution. No atomic write
2	BitOps.PopCount/TrailingZeroCount/HighestSetBit/Log2/NextPowerOfTwo	7 copies in the game. Two NextPowerOfTwo bodies are character-identical (VisitedStateSet.cs:80, VisitedStateDepthMap.cs:143 — verified by diff). Two PopCount bodies are the same SWAR constants over long and ulong	This package carries the same private copies: Core/DataStructure/BitSet.cs:603, ImmutableBitSet.cs:282, and IListExtensions.cs:3144/1069. A public helper removes 4 duplicates here too
3	WallMath.Median/Percentile/Mean/StandardDeviation over IReadOnlyList<T>	Six independent Median bodies over four element types, plus Percentile, Quantile, two Mean, one StandardDeviation. Twelve definitions	WallMath.cs, MathHelpers.cs, Geometry.cs, IEnumerableExtensions.cs, IListExtensions.cs. The only Median here is a private pivot helper
4	Texture2D RotateTexture90(Texture2D, bool), RotateTexture180(Texture2D), ExtractSpriteRect(Sprite)	Pure GetPixels/permute/SetPixels. Preserves source.format and swaps width and height correctly	SpriteHelpers.cs has MakeReadable only. Utils/TextureScale.cs scales. Editor/Sprites/* has no rotation
5	IRandom.NextIntSkewed(int min, int max, float target, int iterations = 3)	The request that started this. Averages k uniform draws, then pulls toward a target, then clamps. Two copies already: one runtime, one bench	NextIntAround/NextFloatAround take a centre and a variance. NextGaussian is unbounded. NextWeighted picks an item. None give a bounded draw biased to a target
6	Exact small-sample statistics: Clopper-Pearson, Fisher exact, sign test, Mantel-Haenszel odds ratio, chi-square survival	1400 lines that import only System, System.Collections.Generic, System.Linq, System.Text.Json. Ships its own self-test battery	No statistics module
7	ShapeHelper.GenerateCircularCurvePoints and two arc variants	Validates arguments and reuses a caller buffer	Utils/CircleLineRenderer.cs computes segments privately for a LineRenderer. No reusable arc API
8	SemaphoreLease — readonly struct : IDisposable for SemaphoreSlim	Prevents two real bugs: a finally spanning the wait releases a slot it never took, and a Release that throws during teardown hides the real failure	Only SingleThreadedThreadPool uses SemaphoreSlim, privately
9	PointerEventData.TryGetWorldPoint/TryGetLocalPoint	Picks the right camera across Overlay, Camera and World canvases. Prefers the raycast hit. Clamps off-screen points	grep -rl PointerEventData Runtime/ Editor/ returns zero files
10	WebGL localStorage binding plus its .jslib	Complete key/value store with a PlayerPrefs fallback behind a define	No localStorage, no __Internal, no DllImport in Runtime/ or Editor/
11	Span<T> overloads for the sort family	The game carries its own introsort over Span<T> because this package has none	18 public sorts here. Every one takes this IList<T>
12	Smaller gaps: Sha256Hex(string), named command-line GetArgument(name), RectTransform→BoxCollider2D sync, pixelDragThreshold by DPI, segment-vs-circle intersection point	Each is one clean method	Sha256Hex: this package has a private copy at Editor/Sprites/SpriteSheetExtractor.cs:4954. GetArgument: Environment.GetCommandLineArgs() is open-coded in 8 places here, all substring scans. Line2D.Intersects(Circle) returns bool; TryGetIntersectionPoint is line-vs-line

One thing to fix rather than adopt

IRandom.NextEnumExcept has overloads for 1, 2, 3, 4, and 4 + params. It has no plain params T[] overload. So a caller with a runtime-length array of fewer than four exclusions cannot call it. DoxReloaded wrote a local extension for exactly that, and the extension is unreachable, because an interface method wins over an extension method. A params T[] overload closes the gap and deletes our copy.

What we are not asking

We do not ask you to take candidates 6, 10 or 11 if they widen the package's scope too far. Say so and we will keep them local. We flag them because they are duplicated or absent, not because they must move.

Filed from DoxReloaded. Reviewer request: https://github.com/Ambiguous-Interactive/DoxReloaded/pull/803#discussion_r3952991525

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PR #746 addresses the runtime-length enum-exclusion gap without changing IRandom, preserving external implementations. New caller tests produced seven compiler errors before the extension and pass afterward. Native Unity 6000.4.6f1 PlayMode passed all 13 selected cases (12 new), with zero skips.

The extension does not displace applicable instance methods. Actual-package C# 9 IL confirms that interface/concrete calls with 1–4 literals retain their fixed-arity overloads and emit no array allocation; 5/8 literals retain the existing four-plus-params overload and one tail array. Passing an existing array reaches the extension with no new array, including its forwarding path above four entries. XML and feature docs explain the distinction.

The ranked helper audit also found two corrections to the adoption backlog on current main: SemaphoreLease already provides acquisition, async acquisition and idempotent release; DurableFile provides text writes/deletion, but not TryWriteAllBytes. These are current-source findings, not a claim that all surfaces exist in release 3.5.1. The other specifically requested public helpers remain gaps; similarly named internal helpers do not satisfy them. Numerical statistics, WebGL storage and span sorting still need the scope decisions requested here.

Full fleet acceptance is running on PR #746 at 00999cb4. This issue remains open for the ranked helper backlog.

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PR #748 adds DurableFile.TryWriteAllBytes for binary saves. Text and byte writes share the staged-write/flush/swap core and the same path gate; text encoding remains inside that gate so queued writers do not retain extra encoded payloads. Null bytes produce an empty file, and failures preserve the previous destination and staging ownership rules.

The missing-API compile regression was observed before implementation. Native Unity 6000.4.6f1 PlayMode passes all 39 DurableFile cases, including 13 new cases for exact binary contents, replacement, null/empty and invalid paths, staging/swap failure, and mixed text/byte writers. Host configurations and independent review pass. The PR fleet is still running.

This completes the byte-write gap in candidate 1. The enum-array fix and SemaphoreLease were already incorporated; the other ranked helper candidates remain open.

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Fix on PR #750. BitOps is now the public home for the shared bit operations: SWAR PopCount (ulong/long/uint/int), zero-safe TrailingZeroCount, floor Log2 with unsigned-rebitcast semantics, HighestSetBit isolation, IsPowerOfTwo, and a fail-closed NextPowerOfTwo that throws ArgumentOutOfRangeException rather than overflowing (the int/long overloads carry explicit bounds so no input can produce a negative result).

The package's private duplicates were swept: the BitSet/ImmutableBitSet popcounts, the sorters' FloorLog2 depth-limit helper (6 call sites across Ska/Pdq/Ipn/Ips4o/Flux) and SmoothSortTrailingZeroCount, and three private Editor IsPowerOfTwo copies; EnumToggleButtonsShared now delegates its public check.

Evidence: a data-driven fixture cross-checks every overload against reference implementations across all power-of-two boundaries and seeded signed ranges. The first native Unity 6000.4.6f1 PlayMode run caught four errors in the fixture's own expected values (Log2(2)=1, IsPowerOfTwo(2)=true, Log2(int.MaxValue)=30, TrailingZeroCount(int.MinValue)=31) — all four were test-data bugs, the implementation held. After correction: 609/609 PlayMode passed, BitSet 249/249, sorting 128/128. Docs section in helper utilities compiles under the doc-sample gate. Remaining ranked candidates (statistics, WebGL storage, span sorts) still need the scope decisions requested above.

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Candidates 3 and 12 ship on PR #749, with the candidate-12 command-line sweep:

Candidate 3 — WallMath descriptive statistics. Median, Percentile, Mean and StandardDeviation over IReadOnlyList<float>/<double>/<int>/<long> (14 methods). Median and percentile sort a pooled copy (Buffers<T>.GetList), so the caller's list is never reordered; even-count medians halve each term in double before adding, so {float.MaxValue, -float.MaxValue} cannot overflow the sum; percentiles validate [0, 1] and interpolate linearly between closest ranks; means accumulate in double, so an int/long sum cannot overflow and integral data returns double like Enumerable.Average; standard deviation is two-pass population by default with sample: true for Bessel's correction. Fail-closed on empty receivers, null receivers, NaN/out-of-range percentiles and sample standard deviation over fewer than two elements. Placement follows the #672 ordering; lint:nested-type-placement is clean.

Candidate 12 — hashing and command-line sweep. Objects.Sha256Hex(string) (UTF-8), Sha256Hex(byte[]) and TrySha256HexOfFile(path, out hex), which reports a missing or unreadable file with false instead of throwing. The sprite sheet tooling's private 20-line ComputeFileHash now delegates to it, so the package owns exactly one SHA-256 implementation. The same sweep collapsed the seven byte-identical IsInvokedByTestRunner() copies (EditorUi, FitTextureSizeWindow, UnityMethodAnalyzerWindow, SpriteSheetAnimationCreator, SpritePivotAdjuster, ScriptableSpriteAtlasEditor, AnimationCopierWindow) into EditorUtilities.IsInvokedByTestRunner(); the SpritePivotAdjuster copy was dead code — defined, never called — and is simply gone.

Evidence: the first native Unity 6000.4.6f1 PlayMode run caught two defects in the statistics implementation itself — Mean/StandardDeviation dereferenced Count before the null check, and the sample-size check fired before the empty check. Both fixed with the throwing tests as the regression evidence. After the fix: WallMathStatisticsTests 40/40 (known vectors, seeded reference cross-checks across sizes 1–40, mutation and null/empty throw cases) and ObjectsSha256Tests 11/11 (empty/abc/pangram/non-ASCII UTF-8 digests, byte/text agreement, file cases) in PlayMode. Full EditMode suite 6420 pass with only the documented pre-existing failures. Doc sections compile under the doc-sample gate.

The issue stays open for the ranked remainder: candidates 4, 6, 7, 9, 10, 11 and 12's smaller gaps need the scope decisions requested above, and candidate 5's NextIntSkewed needs the game's copy as the semantic reference before I would invent semantics for "pulls toward a target".

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Candidate 4 ships on PR #749:

• SpriteHelpers.RotateTexture90(Texture2D, bool clockwise) and RotateTexture180(Texture2D): pure GetPixels32 permutation into a fresh texture — the source is never modified, quarter turns swap width and height, and the source's format is preserved.
• SpriteHelpers.ExtractSpriteRect(Sprite): copies the sprite's textureRect region, so packed atlases where the sprite occupies a sub-rectangle of a larger sheet work. The block Texture2D.GetPixels32(x, y, w, h) overload was deliberately avoided because it is absent from the 2021.3 reference assemblies this package pins its typecheck to.
• Fail-soft contract: a null receiver returns null, and an unreadable or write-protected texture (for example a compressed imported asset) logs a reason and returns null instead of throwing mid-load.

Evidence: a data-driven fixture (SpriteHelpersTests, 14 PlayMode cases through the native editor) pins the exact pixel grids for square, portrait, landscape and single-row sources, counterclockwise vs clockwise mapping, 180-twice identity, quarter-turn composition, and sprite-region extraction against a generated atlas — 14/14 passed. Docs section with compiling samples and a short CHANGELOG entry are included.

The ranked remainder stays open: candidates 5-7, 9-11 and 12's smaller gaps (GetArgument named command-line parsing, RectTransform→BoxCollider2D sync, pixelDragThreshold by DPI, segment-vs-circle intersection point) await the scope decisions requested in the issue, and candidate 8 is already satisfied — the package's SemaphoreLease provides acquisition, async acquisition and idempotent release.