[BUG]: `AddBuildTag()` fails when tag is emoji which isn't a gemstone 💎

[ncook-hxgn]

What happened?

I'm a devops engineer, developing a custom pipeline task for azure devops pipelines. I'd like my task to tag the build with an emoji, (e.g. a cookie because the developer done good, or a warning triangle if they did bad) - but I don't seem to be able to reliably do this.

I seem to be running into this exception:
https://github.com/microsoft/azure-pipelines-agent/blob/master/src/Agent.Worker/Build/BuildCommandExtension.cs#L192

I can hit it from several paths.

1. I've tried to add a tag from within my task, via azure-pipelines-task-lib/task:

import * as tl from 'azure-pipelines-task-lib/task';

tl.addBuildTag("🏷️");

This looks like it has worked at first, but eventually yields and error:

##[debug]Add build tag: 🏷️ to build: 1553 at backend.
##[debug]Processed: ##vso[build.addbuildtag]🏷️
##[debug]SystemVssConnection exists true
##[debug]System.TeamFoundationCollectionUri=https://dev.azure.com/etcetera-etcetera/
##[debug]Tagging build 1553 in project xxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxx with tag '🏷️'

...

Async Command Start: Add Build Tag
Async Command End: Add Build Tag
##[error]Build tag '🏷️' was not added successfully.
##[debug]System.Exception: Build tag '🏷️' was not added successfully.
   at Microsoft.VisualStudio.Services.Agent.Worker.Build.BuildAddBuildTagCommand.AddBuildTagAsync(IAsyncCommandContext context, VssConnection connection, Guid projectId, Int32 buildId, String buildTag, CancellationToken cancellationToken) in D:\a\_work\1\s\src\Agent.Worker\Build\BuildCommandExtension.cs:line 192
   at Microsoft.VisualStudio.Services.Agent.Worker.AsyncCommandContext.WaitAsync() in D:\a\_work\1\s\src\Agent.Worker\AsyncCommandContext.cs:line 130
   at Microsoft.VisualStudio.Services.Agent.Worker.StepsRunner.RunStepAsync(IStep step, CancellationToken jobCancellationToken) in D:\a\_work\1\s\src\Agent.Worker\StepsRunner.cs:line 417

2. I've also tried to add a tag form within my task, via azure-devops-node-api:

import * as tl from 'azure-pipelines-task-lib/task';
import * as wa from 'azure-devops-node-api/WebApi';
import * as ba from 'azure-devops-node-api/BuildApi';

export async function tagBuild(tag: string): Promise<void> {
    let buildApi: ba.IBuildApi = await getBuildApiInstance();
    const projectId = tl.getVariable('System.TeamProjectId');
    const buildId = parseInt(tl.getVariable('Build.BuildId'));
    tl.debug(`Tagging build ${buildId} in project ${projectId} with tag '${tag}'`);
    await buildApi.addBuildTag(projectId, buildId, tag);
};

But this just gives me a 💎, not a 🏷️.
I see my tag in the build log's debug stream (tl.debug() above) -- and no errors, it does actually tag the build:

...
##[debug]Tagging build 1550 in project xxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxx with tag '🏷️'
...

But the tag I get isn't a 🏷️ ... it's a 💎:

3. I've tried also inline PowerShell:

    - task: PowerShell@2
      displayName: "Tag 🏷️"
      condition: always()
      inputs:
        targetType: 'inline'
        script: |
          Write-Host "##vso[build.addbuildtag]🏷️"
        workingDirectory: '$(Build.SourcesDirectory)'

This yields:

##[debug]Add build tag: 🏷️ to build: 1545 at backend.
##[debug]Processed: ##vso[build.addbuildtag]🏷️
##[debug]$LASTEXITCODE is not set.
##[debug]Exit code: 0
##[debug]Leaving Invoke-VstsTool.
##[debug]Leaving S:\a\_tasks\PowerShell_e213ff0f-5d5c-4791-802d-52ea3e7be1f1\2.266.0\powershell.ps1.
Async Command Start: Add Build Tag
Async Command End: Add Build Tag
##[error]Build tag '🏷️' was not added successfully.
##[debug]System.Exception: Build tag '🏷️' was not added successfully.
   at Microsoft.VisualStudio.Services.Agent.Worker.Build.BuildAddBuildTagCommand.AddBuildTagAsync(IAsyncCommandContext context, VssConnection connection, Guid projectId, Int32 buildId, String buildTag, CancellationToken cancellationToken) in D:\a\_work\1\s\src\Agent.Worker\Build\BuildCommandExtension.cs:line 192
   at Microsoft.VisualStudio.Services.Agent.Worker.AsyncCommandContext.WaitAsync() in D:\a\_work\1\s\src\Agent.Worker\AsyncCommandContext.cs:line 130
   at Microsoft.VisualStudio.Services.Agent.Worker.StepsRunner.RunStepAsync(IStep step, CancellationToken jobCancellationToken) in D:\a\_work\1\s\src\Agent.Worker\StepsRunner.cs:line 417
Finishing: Tag 🏷️

However, it works when I ask for a gemstone. Other emojis that I've tried fail:

    - task: PowerShell@2
      displayName: "Tag 💎"
      condition: always()
      inputs:
        targetType: 'inline'
        script: |
          Write-Host "##vso[build.addbuildtag]💎"
        workingDirectory: '$(Build.SourcesDirectory)'

    - task: PowerShell@2
      displayName: "Tag 🏷️"
      condition: always()
      inputs:
        targetType: 'inline'
        script: |
          Write-Host "##vso[build.addbuildtag]🏷️"
        workingDirectory: '$(Build.SourcesDirectory)'

    - task: PowerShell@2
      displayName: "Tag 📢"
      condition: always()
      inputs:
        targetType: 'inline'
        script: |
          Write-Host "##vso[build.addbuildtag]📢"
        workingDirectory: '$(Build.SourcesDirectory)'

    - task: PowerShell@2
      displayName: "Tag 🍪"
      condition: always()
      inputs:
        targetType: 'inline'
        script: |
          Write-Host "##vso[build.addbuildtag]🍪"
        workingDirectory: '$(Build.SourcesDirectory)'

Yields the following outputs:
(for what it's worth, adding the 💎 works, even if I run the task last after the other three fail)

Async Command Start: Add Build Tag
Build '1546' has following tags now: 💎
Async Command End: Add Build Tag
Finishing: Tag 💎

Async Command Start: Add Build Tag
Async Command End: Add Build Tag
##[error]Build tag '🏷️' was not added successfully.
Finishing: Tag 🏷️

Async Command Start: Add Build Tag
Async Command End: Add Build Tag
##[error]Build tag '📢' was not added successfully.
Finishing: Tag 📢

Async Command Start: Add Build Tag
Async Command End: Add Build Tag
##[error]Build tag '🍪' was not added successfully.
Finishing: Tag 🍪

I do plan on using the 💎, but I'd like to use some others as well.

Versions

• Current agent version: '4.266.2'
• Windows Server 2025

Environment type (Please select at least one enviroment where you face this issue)

• Self-Hosted
• Microsoft Hosted
• VMSS Pool
• Container

Azure DevOps Server type

dev.azure.com (formerly visualstudio.com)

Azure DevOps Server Version (if applicable)

No response

Operation system

all

Version controll system

Git

Relevant log output

[ncook-hxgn]

I decided to enumerate emojis and try to tag my build with each of them...

stages:
- stage: Shakedown
  dependsOn: []
  jobs:
  - job: Shakedown
    dependsOn: []
    steps:
    - checkout: self
    - task: PowerShell@2
      displayName: "Emoji"
      condition: always()
      inputs:
        targetType: 'inline'
        script: |
          # Common emoji Unicode ranges
          $emojiRanges = @(
              @{ Start = 0x1F600; End = 0x1F64F; Name = "Emoticons" },
              @{ Start = 0x1F300; End = 0x1F5FF; Name = "Misc Symbols & Pictographs" },
              @{ Start = 0x1F680; End = 0x1F6FF; Name = "Transport & Map Symbols" },
              @{ Start = 0x1F900; End = 0x1F9FF; Name = "Supplemental Symbols" },
              @{ Start = 0x1FA00; End = 0x1FA6F; Name = "Chess & Extended Symbols" },
              @{ Start = 0x1FA70; End = 0x1FAFF; Name = "Symbols & Pictographs Extended-A" },
              @{ Start = 0x2600;  End = 0x26FF;  Name = "Misc Symbols" },
              @{ Start = 0x2700;  End = 0x27BF;  Name = "Dingbats" }
          )
          foreach ($range in $emojiRanges) {
              Write-Host "`n=== $($range.Name) ===" -ForegroundColor Cyan
              for ($i = $range.Start; $i -le $range.End; $i++) {
                  $emoji = [char]::ConvertFromUtf32($i)
                  Write-Host "Trying to create a tag with"
                  Write-Host "##vso[build.addbuildtag]$emoji"
              }
          }
        workingDirectory: '$(Build.SourcesDirectory)'

Here's the log that shows exactly which emoji's do and don't work (too big for a github snippet):

1152.txt

[ncook-hxgn]

(please forgive my many edits)