diff --git a/.github/actions/spell-check/dictionary/apis.txt b/.github/actions/spell-check/dictionary/apis.txt
index 1bf739dcf..30bfef9ce 100644
--- a/.github/actions/spell-check/dictionary/apis.txt
+++ b/.github/actions/spell-check/dictionary/apis.txt
@@ -8,8 +8,9 @@ EXPCMDSTATE
 href
 IBox
 IBind
-ICustom
 IClass
+IComparable
+ICustom
 IExplorer
 IMap
 IObject
diff --git a/.github/actions/spell-check/expect/expect.txt b/.github/actions/spell-check/expect/expect.txt
index 8334d6e82..2550c0ca5 100644
--- a/.github/actions/spell-check/expect/expect.txt
+++ b/.github/actions/spell-check/expect/expect.txt
@@ -1511,11 +1511,13 @@ NOTHOUSANDS
 nothrow
 NOTICKS
 NOTIMPL
+notin
 NOTNULL
 NOTRACK
 NOTSUPPORTED
 notypeopt
 nouicompat
+nounihan
 NOUPDATE
 NOWAIT
 NOYIELD
@@ -2376,9 +2378,11 @@ typeparam
 TYUI
 uap
 uapadmin
+UAX
 ubuntu
 ucd
 UCD
+ucdxml
 uch
 UCHAR
 ucs
diff --git a/tools/Generate-CodepointWidthsFromUCD.ps1 b/tools/Generate-CodepointWidthsFromUCD.ps1
new file mode 100644
index 000000000..788e53892
--- /dev/null
+++ b/tools/Generate-CodepointWidthsFromUCD.ps1
@@ -0,0 +1,274 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+#Requires -Version 7
+# (we use the null coalescing operator)
+
+################################################################################
+# This script generates the an array suitable for replacing the body of
+# src/types/CodepointWidthDetector.cpp from a Unicode UCD XML document[1]
+# compliant with UAX#42[2].
+#
+# This script supports a quasi-mandatory "overrides" file, overrides.xml.
+# If you do not have overrides, supply the -NoOverrides parameter. This was
+# developed for use with the CodepointWidthDetector, which has some override
+# ranges.
+#
+# This script was developed against the flat "no han unification" UCD
+# "ucd.nounihan.flat.xml".
+# It does not support the grouped database format.
+# significantly smaller, which would provide a performance win on the admittedly
+# extremely rare occasion that we should need to regenerate our table.
+#
+# Invoke as ./Generate-xxx ucd.nounihan.flat.xml -Pack | Out-File -Encoding
+#           UTF-8 Temporary.cpp
+#
+# [1]: https://www.unicode.org/Public/UCD/latest/ucdxml/
+# [2]: https://www.unicode.org/reports/tr42/
+
+[Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSAvoidUsingPositionalParameters', '')]
+[Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSUseProcessBlockForPipelineCommand', '')]
+[CmdletBinding()]
+Param(
+    [Parameter(Position=0, ValueFromPipeline=$true, ParameterSetName="Parsed")]
+    [System.Xml.XmlDocument]$InputObject,
+
+    [Parameter(Position=1, ValueFromPipeline=$true, ParameterSetName="Parsed")]
+    [System.Xml.XmlDocument]$OverrideObject,
+
+    [Parameter(Position=0, ValueFromPipelineByPropertyName=$true, ParameterSetName="Unparsed")]
+    [string]$Path = "ucd.nounihan.flat.xml",
+
+    [Parameter(Position=1, ValueFromPipelineByPropertyName=$true, ParameterSetName="Unparsed")]
+    [string]$OverridePath = "overrides.xml",
+
+    [switch]$Pack, # Pack tightly based on width
+    [switch]$NoOverrides, # Do not include overrides
+    [switch]$Full = $False # Include Narrow codepoints
+)
+
+Enum CodepointWidth {
+    Narrow;
+    Wide;
+    Ambiguous;
+    Invalid;
+}
+
+# UCD Functions {{{
+Function Get-UCDEntryRange($entry) {
+    $s = $e = 0
+    if ($null -ne $v.cp) {
+        # Individual Codepoint
+        $s = $e = [int]("0x"+$v.cp)
+    } ElseIf ($null -ne $v."first-cp") {
+        # Range of Codepoints
+        $s = [int]("0x"+$v."first-cp")
+        $e = [int]("0x"+$v."last-cp")
+    }
+    $s
+    $e
+}
+
+Function Get-UCDEntryWidth($entry) {
+    If ($entry.Emoji -eq "Y" -and $entry.EPres -eq "Y") {
+        [CodepointWidth]::Wide
+        Return
+    }
+
+    Switch($entry.ea) {
+        "N"  { [CodepointWidth]::Narrow; Return }
+        "Na" { [CodepointWidth]::Narrow; Return }
+        "H"  { [CodepointWidth]::Narrow; Return }
+        "W"  { [CodepointWidth]::Wide; Return }
+        "F"  { [CodepointWidth]::Wide; Return }
+        "A"  { [CodepointWidth]::Ambiguous; Return }
+    }
+    [CodepointWidth]::Invalid
+}
+
+Function Get-UCDEntryFlags($entry) {
+    If ($script:Pack) {
+        # If we're "pack"ing entries, only the computed width matters for telling them apart
+        Get-UCDEntryWidth $entry
+        Return
+    }
+
+    $normalizedEAWidth = $entry.ea
+    $normalizedEAWidth = $normalizedEAWidth -eq "F" ? "W" : $normalizedEAWidth;
+    "{0}{1}{2}" -f $normalizedEAWidth, $entry.Emoji, $entry.EPres
+}
+# }}}
+
+Class UnicodeRange : System.IComparable {
+    [int]$Start
+    [int]$End
+    [CodepointWidth]$Width
+    [string]$Flags
+    [string]$Comment
+
+    UnicodeRange([System.Xml.XmlElement]$ucdEntry) {
+        $this.Start, $this.End = Get-UCDEntryRange $ucdEntry
+        $this.Width = Get-UCDEntryWidth $ucdEntry
+        $this.Flags = Get-UCDEntryFlags $ucdEntry
+
+        If (-not $script:Pack -and $ucdEntry.Emoji -eq "Y" -and $ucdEntry.EPres -eq "Y") {
+            $this.Comment = "Emoji=Y EPres=Y"
+        }
+
+        If ($null -ne $ucdEntry.comment) {
+            $this.Comment = $ucdEntry.comment
+        }
+    }
+
+    [int] CompareTo([object]$Other) {
+        If ($Other -is [int]) {
+            Return $this.Start - $Other
+        }
+        Return $this.Start - $Other.Start
+    }
+
+    [bool] Merge([UnicodeRange]$Other) {
+        # If there's more than one codepoint between them, don't merge
+        If (($Other.Start - $this.End) -gt 1) {
+            Return $false
+        }
+
+        # Flags are different: do not merge
+        If ($this.Flags -ne $Other.Flags) {
+            Return $false
+        }
+
+        $this.End = $Other.End
+        Return $true
+    }
+
+    [int] Length() {
+        return $this.End - $this.Start + 1
+    }
+}
+
+Class UnicodeRangeList : System.Collections.Generic.List[Object] {
+    UnicodeRangeList([int]$Capacity) : base($Capacity) { }
+
+    [int] hidden _FindInsertionPoint([int]$codepoint) {
+        $l = $this.BinarySearch($codepoint)
+        If ($l -lt 0) {
+            # Return value <0: value was not found, return value is bitwise complement the index of the first >= value
+            Return -bNOT $l
+        }
+        Return $l
+    }
+
+    ReplaceUnicodeRange([UnicodeRange]$newRange) {
+        $subset = [System.Collections.Generic.List[Object]]::New(3)
+        $subset.Add($newRange)
+
+        $i = $this._FindInsertionPoint($newRange.Start)
+
+        # Left overlap can only ever be one (_FindInsertionPoint always returns the
+        # index immediately after the range whose Start is <= than ours).
+        $prev = $null
+        If($i -gt 0 -and $this[$i - 1].End -ge $newRange.Start) {
+            $prev = $i - 1
+        }
+
+        # Right overlap can be Infinite (because we didn't account for End)
+        # Find extent of right overlap
+        For($next = $i; ($next -lt $this.Count - 1) -and ($this[$next+1].Start -le $newRange.End); $next++) { }
+        If ($this[$next].Start -gt $newRange.End) {
+            # It turns out we didn't damage the following range; clear it
+            $next = $null
+        }
+
+        If ($null -ne $next) {
+            # Replace damaged elements after I with a truncated range
+            $last = $this[$next]
+            $this.RemoveRange($i, $next - $i + 1) # Remove damaged elements after I
+            $last.Start = $newRange.End + 1
+            If ($last.Start -le $last.End) {
+                $subset.Add($last)
+            }
+        }
+
+        If ($null -ne $prev) {
+            # Replace damaged elements before I with a truncated range
+            $first = $this[$prev]
+            $this.RemoveRange($prev, $i - $prev) # Remove damaged elements (b/c we may not need to re-add them!)
+            $first.End = $newRange.Start - 1
+            If ($first.End -ge $first.Start) {
+                $subset.Insert(0, $first)
+            }
+            $i = $prev # Update the insertion cursor
+        }
+
+        $this.InsertRange($i, $subset)
+    }
+}
+
+# Ingest UCD
+If ($null -eq $InputObject) {
+    $InputObject = [xml](Get-Content $Path)
+}
+
+$UCDRepertoire = $InputObject.ucd.repertoire.ChildNodes | Sort-Object {
+    # Sort by either cp or first-cp (for ranges)
+    if ($null -ne $_.cp) {
+        [int]("0x"+$_.cp)
+    } ElseIf ($null -ne $_."first-cp") {
+        [int]("0x"+$_."first-cp")
+    }
+}
+
+If (-not $Full) {
+    $UCDRepertoire = $UCDRepertoire | Where-Object {
+        # Select everything Wide/Ambiguous/Full OR Emoji w/ Emoji Presentation
+        ($_.ea -notin "N", "Na", "H") -or ($_.Emoji -eq "Y" -and $_.EPres -eq "Y")
+    }
+}
+
+$ranges = [UnicodeRangeList]::New(1024)
+
+$c = 0
+ForEach($v in $UCDRepertoire) {
+    $range = [UnicodeRange]::new($v)
+    $c += $range.Length()
+
+    If ($ranges.Count -gt 0 -and $ranges[$ranges.Count - 1].Merge($range)) {
+        # Merged into last entry
+        Continue
+    }
+    $ranges.Add([object]$range)
+}
+
+If (-not $NoOverrides) {
+    If ($null -eq $OverrideObject) {
+        $OverrideObject = [xml](Get-Content $OverridePath)
+    }
+
+    $OverrideRepertoire = $OverrideObject.ucd.repertoire.ChildNodes
+    $overrideCount = 0
+    ForEach($v in $OverrideRepertoire) {
+        $range = [UnicodeRange]::new($v)
+        $overrideCount += $range.Length()
+        $range.Comment = $range.Comment ?? "overridden without comment"
+        $ranges.ReplaceUnicodeRange($range)
+    }
+}
+
+# Emit Code
+"    // Generated by {0} -Pack:{1} -Full:{2} -NoOverrides:{3}" -f $MyInvocation.MyCommand.Name, $Pack, $Full, $NoOverrides
+"    // on {0} (UTC) from {1}." -f (Get-Date -AsUTC), $InputObject.ucd.description
+"    // {0} (0x{0:X}) codepoints covered." -f $c
+If (-not $NoOverrides) {
+"    // {0} (0x{0:X}) codepoints overridden." -f $overrideCount
+}
+"    static constexpr std::array<UnicodeRange, {0}> s_wideAndAmbiguousTable{{" -f $ranges.Count
+ForEach($_ in $ranges) {
+    $comment = ""
+    if ($null -ne $_.Comment) {
+        # We only vend comments when we aren't packing tightly
+        $comment = " // {0}" -f $_.Comment
+    }
+"        UnicodeRange{{ 0x{0:x}, 0x{1:x}, CodepointWidth::{2} }},{3}" -f $_.Start, $_.End, $_.Width, $comment
+}
+"    };"