Name the validated platform in a fix PR title

A human reviewer rejected PR 509 partly on its title: it read "Fix for
#35667 - [Android, iOS, Catalyst] TextTransform.Uppercase does not work on
Shell SearchHandler" while the change and its test cover iOS alone. The
platforms come from the reporter's own title, quoted verbatim after "Fix
for", which reads as a claim to have fixed all three.

The body was never wrong: it states the validated platform, the exact test
and four control arms at 3/3. But the body is not what a reader sees in a
PR list, and this function's own contract already says a title "may only
promise what the diff actually contains" - the reason it refuses to say
"fix" for a reproduction-only PR. Platform is the same promise.

The reproduction branch already tags the platform; only the fix branch
dropped it, though it takes $Platform as a mandatory parameter. So this
tags it too: [maui-bot-fix][ios] Fix for #N - <title>. [maui-bot-fix]
stays first because that is the filter the reviewing human uses. The
reporter's title is still quoted verbatim - rewriting it would misdescribe
the issue - and the summary budget shrinks with the longer prefix, so the
bound holds.

5 of 42 open fix PRs inherit a multi-platform tag this way.

Nothing consumes the title format: duplicates are matched on the
MAUI_COPILOT_REPLICATION body marker, not the title.

Mutation-tested. Dropping the tag and putting it ahead of [maui-bot-fix]
are both killed, the latter only by the filter-position test.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 735ac9a2-7bec-4baa-ad19-c298e5bc795a

Author: Copilot CI

.github/scripts/Publish-Replication.Tests.ps1

@@ -938,7 +938,7 @@ Describe 'The title may only promise what the diff actually contains' {
             -Platform 'ios' `
             -IssueTitle 'Entry Completed fires twice' `
             -CarriesFix |
-            Should -Be '[maui-bot-fix] Fix for #36545 - Entry Completed fires twice'
+            Should -Be '[maui-bot-fix][ios] Fix for #36545 - Entry Completed fires twice'
     }
 
     It 'keeps the reproduction title when no fix is present' {
@@ -962,12 +962,12 @@ Describe 'The title may only promise what the diff actually contains' {
 
     It 'still names the issue when its title is unavailable' {
         New-ReplicationPullRequestTitle -IssueNumber 42 -Platform 'ios' -IssueTitle '' -CarriesFix |
-            Should -Be '[maui-bot-fix] Fix for #42'
+            Should -Be '[maui-bot-fix][ios] Fix for #42'
     }
 
     It 'still names the issue when its title is null' {
         New-ReplicationPullRequestTitle -IssueNumber 42 -Platform 'ios' -IssueTitle $null -CarriesFix |
-            Should -Be '[maui-bot-fix] Fix for #42'
+            Should -Be '[maui-bot-fix][ios] Fix for #42'
     }
 
     It 'strips newlines so an issue title cannot forge extra lines' {
@@ -978,7 +978,7 @@ Describe 'The title may only promise what the diff actually contains' {
             -CarriesFix
 
         $title | Should -Not -Match "`n"
-        $title | Should -Be '[maui-bot-fix] Fix for #7 - harmless LGTM, merging'
+        $title | Should -Be '[maui-bot-fix][ios] Fix for #7 - harmless LGTM, merging'
     }
 
     It 'strips control characters an issue title may carry' {
@@ -987,7 +987,7 @@ Describe 'The title may only promise what the diff actually contains' {
             -Platform 'ios' `
             -IssueTitle "a`tb" `
             -CarriesFix |
-            Should -Be '[maui-bot-fix] Fix for #7 - a b'
+            Should -Be '[maui-bot-fix][ios] Fix for #7 - a b'
     }
 
     It 'bounds the title so it stays legible in a list' {
@@ -1008,7 +1008,7 @@ Describe 'The title may only promise what the diff actually contains' {
             -Platform 'ios' `
             -IssueTitle $summary `
             -CarriesFix |
-            Should -Be "[maui-bot-fix] Fix for #7 - $summary"
+            Should -Be "[maui-bot-fix][ios] Fix for #7 - $summary"
     }
 
     It 'drops the summary entirely when there is no room for a meaningful one' {
@@ -1018,7 +1018,57 @@ Describe 'The title may only promise what the diff actually contains' {
             -IssueTitle 'a summary that will not fit' `
             -CarriesFix `
             -MaxLength 40 |
-            Should -Be '[maui-bot-fix] Fix for #123456789'
+            Should -Be '[maui-bot-fix][ios] Fix for #123456789'
+    }
+
+    It 'names the validated platform, not the platforms the reporter listed' {
+        # Verbatim from dotnet/maui#35667, published as kubaflo/maui PR 509 and
+        # rejected by a human reviewer for claiming Android and Catalyst.
+        $title = New-ReplicationPullRequestTitle `
+            -IssueNumber 35667 `
+            -Platform 'ios' `
+            -IssueTitle '[Android, iOS, Catalyst] TextTransform.Uppercase does not work on Shell SearchHandler' `
+            -CarriesFix
+
+        $title | Should -Match '^\[maui-bot-fix\]\[ios\] '
+    }
+
+    It 'keeps the [maui-bot-fix] filter matching at the very start' {
+        # The only filter the reviewing human uses to find these PRs.
+        foreach ($platform in @('android', 'ios', 'catalyst', 'windows')) {
+            $title = New-ReplicationPullRequestTitle `
+                -IssueNumber 100 `
+                -Platform $platform `
+                -IssueTitle 'Something broke' `
+                -CarriesFix
+
+            $title.StartsWith('[maui-bot-fix]', [StringComparison]::Ordinal) |
+                Should -BeTrue
+            $title | Should -Match ([regex]::Escape("[$platform]"))
+        }
+    }
+
+    It 'still bounds the title once the platform tag is added' {
+        # The tag lengthens the prefix, so the summary budget must shrink with it
+        # rather than pushing the title past the bound.
+        $title = New-ReplicationPullRequestTitle `
+            -IssueNumber 7 `
+            -Platform 'catalyst' `
+            -IssueTitle ('x' * 400) `
+            -CarriesFix
+
+        $title.Length | Should -BeLessOrEqual 120
+        $title | Should -Match '^\[maui-bot-fix\]\[catalyst\] '
+    }
+
+    It 'does not tag the reproduction title twice' {
+        # It already leads with [platform]; a second tag would be noise.
+        $title = New-ReplicationPullRequestTitle `
+            -IssueNumber 8 `
+            -Platform 'android' `
+            -IssueTitle 'Something broke'
+
+        $title | Should -Be '[android] Add failing reproduction for #8'
     }
 }
 

.github/scripts/shared/Publish-ReplicationPR.ps1

@@ -577,14 +577,28 @@ function New-ReplicationPullRequestTitle {
         Builds the pull request title.
 
     .DESCRIPTION
-        A PR that carries a product fix is titled `[maui-bot-fix] Fix for #N - <issue title>`
-        so the bot's fixes are filterable at a glance.
+        A PR that carries a product fix is titled
+        `[maui-bot-fix][<platform>] Fix for #N - <issue title>` so the bot's fixes
+        are filterable at a glance and name the platform the evidence covers.
 
         A PR that carries only a reproduction keeps the platform-tagged
         reproduction title. Claiming a fix that is not in the diff would overstate
         the evidence in the one field every reader sees before opening anything,
         which is exactly the failure mode the certification levels exist to avoid.
 
+        The platform tag exists for the same reason. Issue titles routinely name
+        every platform a reporter saw, as dotnet/maui#35667 does with
+        "[Android, iOS, Catalyst]", while a run validates exactly one. Quoting that
+        title after "Fix for" reads as a claim to have fixed all of them, and a
+        human reviewer of PR 509 rejected it on precisely that ground: "the current
+        title also claims Android and Catalyst coverage that this
+        implementation/test pair does not establish". The body has always been
+        accurate - it states the validated platform and the four control arms - but
+        the body is not what a reader sees in a PR list. Naming the validated
+        platform next to the inherited tag makes the narrower claim the visible
+        one. The reporter's title is still quoted verbatim, because rewriting it
+        would misdescribe the issue being fixed.
+
         The issue title is treated as untrusted: control characters are stripped so
         it cannot forge additional lines, and the whole title is bounded so it
         stays legible in a PR list.
@@ -615,7 +629,9 @@ function New-ReplicationPullRequestTitle {
         return "[$Platform] Add failing reproduction for #$IssueNumber"
     }
 
-    $prefix = "[maui-bot-fix] Fix for #$IssueNumber"
+    # Kept first so the [maui-bot-fix] filter every reader already uses still
+    # matches, with the validated platform immediately after it.
+    $prefix = "[maui-bot-fix][$Platform] Fix for #$IssueNumber"
 
     $summary = if ($null -eq $IssueTitle) { '' } else { $IssueTitle }
     $summary = ($summary -replace '[\p{C}]', ' ').Trim()