Consolidate Helix shards for quick test assemblies via MethodLimitMultiplier

.github/actions/select-copilot-pat/README.md

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+# Select Copilot PAT
+
+Selects a random Copilot PAT from a numbered pool of secrets. This addresses
+limitations that arise from having a single PAT shared across all workflows
+that call the Copilot API, such as rate-limiting.
+
+> **This is a stop-gap workaround.** As soon as organization/enterprise billing
+> is offered for agentic workflows, this approach will be removed.
+
+Based on the pattern established in [dotnet/runtime#126057](https://github.com/dotnet/runtime/pull/126057).
+
+## Repository Onboarding
+
+1. Copy this `select-copilot-pat` folder into the repository under
+   `.github/actions/select-copilot-pat`, including both the `README.md`
+   and `action.yml`.
+2. Add repository secrets named `COPILOT_PAT_0` through `COPILOT_PAT_9`
+   (you only need as many as you have team members contributing PATs).
+3. Reference the action in your workflow (see Usage below).
+
+## PAT Creation
+
+[Use this link to prefill the PAT creation form with the required settings][create-pat]:
+
+1. **Resource owner** is your **user account**, not an organization.
+2. **Copilot Requests (Read)** must be the only permission granted.
+3. **8-day expiration** must be used, which enforces a weekly renewal.
+4. **Repository access** set to **Public repositories** only.
+
+Team members providing PATs should set weekly recurring reminders to
+regenerate and update their PATs in the repository secrets.
+
+PATs are added through **Settings > Secrets and variables > Actions**,
+saved as **Repository secrets** matching the `COPILOT_PAT_<0-9>` naming
+convention. This can also be done using the GitHub CLI:
+
+```sh
+gh secret set "COPILOT_PAT_0" --body "<your-github-pat>" --repo dotnet/sdk
+```
+
+## Usage
+
+Add a job that selects a PAT, then consume it in downstream jobs:
+
+```yaml
+jobs:
+  select-pat:
+    name: Select Copilot PAT
+    runs-on: ubuntu-latest
+    outputs:
+      copilot_pat_number: ${{ steps.select-copilot-pat.outputs.copilot_pat_number }}
+    steps:
+      - name: Checkout select-copilot-pat action
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+          sparse-checkout: .github/actions/select-copilot-pat
+          sparse-checkout-cone-mode: true
+          fetch-depth: 1
+
+      - id: select-copilot-pat
+        name: Select Copilot token from pool
+        uses: ./.github/actions/select-copilot-pat
+        env:
+          SECRET_0: ${{ secrets.COPILOT_PAT_0 }}
+          SECRET_1: ${{ secrets.COPILOT_PAT_1 }}
+          # ... up to SECRET_9
+
+  my-ai-job:
+    needs: [select-pat]
+    steps:
+      - name: Call Copilot API
+        env:
+          COPILOT_TOKEN: ${{ needs.select-pat.outputs.copilot_pat_number == '0' && secrets.COPILOT_PAT_0 || needs.select-pat.outputs.copilot_pat_number == '1' && secrets.COPILOT_PAT_1 || '' }}
+        run: |
+          curl -X POST https://api.githubcopilot.com/chat/completions \
+            -H "Authorization: Bearer $COPILOT_TOKEN" \
+            -H "Content-Type: application/json" \
+            -d '{"model":"gpt-4o-mini","messages":[...]}'
+```
+
+## Output Attribution
+
+Team members' PATs are _only_ used for Copilot API requests. All other
+workflow outputs (issues, comments, labels) use the `github-actions[bot]`
+token and are attributed accordingly.
+
+## References
+
+- [dotnet/runtime#126057 — Set up GitHub Agentic Workflows](https://github.com/dotnet/runtime/pull/126057)
+- [PAT creation link][create-pat]
+
+[create-pat]: https://github.com/settings/personal-access-tokens/new?name=dotnet%20org%20agentic%20workflows&description=GitHub+Agentic+Workflows+-+Copilot+API+authentication.++Used+for+dotnet+org+workflows.+MUST+be+configured+with+only+Copilot+Requests+permissions+and+user+account+as+resource+owner.+Weekly+expiration+and+required+renewal.&user_copilot_requests=read&expires_in=8

.github/actions/select-copilot-pat/action.yml

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+name: 'Select Copilot PAT from Pool'
+description: >
+  Selects a random Copilot PAT from a numbered pool of secrets. Secrets
+  are passed as environment variables SECRET_0 through SECRET_9
+  by the calling workflow step.
+
+inputs:
+  random-seed:
+    description: 'A seed number to use for the random PAT selection, for deterministic selection if needed.'
+    required: false
+    default: ''
+
+outputs:
+  copilot_pat_number:
+    description: 'The 0-9 secret number selected from the pool of specified secrets'
+    value: ${{ steps.select-pat-number.outputs.copilot_pat_number }}
+
+runs:
+  using: composite
+  steps:
+    - id: select-pat-number
+      shell: bash
+      env:
+        RANDOM_SEED: ${{ inputs.random-seed }}
+      run: |
+        # Collect all secret numbers with non-empty values from SECRET_0..SECRET_9
+        PAT_NUMBERS=()
+        for i in $(seq 0 9); do
+          var="SECRET_${i}"
+          val="${!var}"
+          if [ -n "$val" ]; then
+            PAT_NUMBERS+=(${i})
+          fi
+        done
+
+        # If none of the secrets in the pool have values, then emit a warning and do not
+        # set an output value. The consumer can then fall back to using COPILOT_GITHUB_TOKEN.
+        if [ ${#PAT_NUMBERS[@]} -eq 0 ]; then
+          echo "::warning::None of the specified secrets had values (checked SECRET_0 through SECRET_9)"
+          exit 0
+        fi
+
+        # Select a random index using the seed if specified
+        if [ -n "$RANDOM_SEED" ]; then
+          RANDOM=$RANDOM_SEED
+        fi
+
+        PAT_INDEX=$(( RANDOM % ${#PAT_NUMBERS[@]} ))
+        PAT_NUMBER="${PAT_NUMBERS[$PAT_INDEX]}"
+        echo "Selected token ${PAT_NUMBER} (index: ${PAT_INDEX}; pool size: ${#PAT_NUMBERS[@]})"
+
+        # Set the PAT number as the output
+        echo "copilot_pat_number=${PAT_NUMBER}" >> "$GITHUB_OUTPUT"

.github/aw/actions-lock.json

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+{
+  "entries": {
+    "actions/github-script@v9": {
+      "repo": "actions/github-script",
+      "version": "v9",
+      "sha": "373c709c69115d41ff229c7e5df9f8788daa9553"
+    },
+    "github/gh-aw-actions/setup@v0.68.3": {
+      "repo": "github/gh-aw-actions/setup",
+      "version": "v0.68.3",
+      "sha": "ba90f2186d7ad780ec640f364005fa24e797b360"
+    }
+  }
+}

.github/copilot-instructions.md

@@ -22,9 +22,10 @@ Testing:
   - Examples:
     - `dotnet test test/dotnet.Tests/dotnet.Tests.csproj --filter "Name~ItShowsTheAppropriateMessageToTheUser"`
     - `dotnet exec artifacts/bin/redist/Debug/dotnet.Tests.dll -method "*ItShowsTheAppropriateMessageToTheUser*"`
+- For incremental test runs of `dotnet.Tests` (avoids slow full `build.cmd`), use the `incremental-test` skill.
 - To test CLI command changes:
   - Build the redist SDK: `./build.sh` from repo root
-  - Create a dogfood environment: `source eng/dogfood.sh` 
+  - Create a dogfood environment: `source eng/dogfood.sh`
   - Test commands in the dogfood shell (e.g., `dnx --help`, `dotnet tool install --help`)
   - The dogfood script sets up PATH and environment to use the newly built SDK
 

.github/skills/AGENTS.md

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+# Agent Skills
+
+When creating skills, follow:
+- Agent skills specification: https://agentskills.io/specification.md
+- Best practices: https://agentskills.io/skill-creation/best-practices.md
+
+## Structure
+
+```
+.github/skills/skill-name/
+├── SKILL.md          # Required: metadata + instructions
+├── scripts/          # Optional: executable code
+├── references/       # Optional: documentation
+├── assets/           # Optional: templates, resources
+└── ...               # Any additional files or directories
+```
+
+## Quick Checklist
+
+- [ ] Run `dotnet .github/skills/ValidateSkill.cs <skill-dir>` to validate format.
+- [ ] `description` describes what the skill does and when to use it. Skill body does not include "When to use this skill".
+- [ ] Skill does not explain things the agent already knows. Focus on what's specific to the task at hand.
+- [ ] Deterministic processes use scripts (for example, to fetch and format data from an API).
+- [ ] Scripts use PowerShell or .NET file-based apps, not bash.

.github/skills/ValidateSkill.cs

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+#!/usr/bin/env dotnet
+#:property ManagePackageVersionsCentrally=false
+#:property PublishAot=false
+#:package YamlDotNet@16.3.0
+
+using YamlDotNet.Serialization;
+using System.Text.RegularExpressions;
+
+if (args.Length == 0)
+{
+    Console.Error.WriteLine("Usage: dotnet ValidateSkill.cs <path-to-skill-directory>");
+    return 1;
+}
+
+string skillDir = Path.GetFullPath(args[0]);
+string skillName = Path.GetFileName(Path.TrimEndingDirectorySeparator(skillDir));
+string skillFile = Path.Combine(skillDir, "SKILL.md");
+
+// SKILL.md must exist in the skill directory
+if (!File.Exists(skillFile))
+{
+    Console.Error.WriteLine($"SKILL.md not found in {skillDir}");
+    return 1;
+}
+
+string text = File.ReadAllText(skillFile);
+
+// SKILL.md must begin with YAML frontmatter delimited by ---
+if (!text.StartsWith("---"))
+{
+    Console.Error.WriteLine("No YAML frontmatter found.");
+    return 1;
+}
+
+Match frontmatterMatch = Regex.Match(
+    text,
+    @"\A---\r?\n(?<yaml>.*?)(?:\r?\n)---(?:\r?\n|$)",
+    RegexOptions.Singleline);
+if (!frontmatterMatch.Success)
+{
+    Console.Error.WriteLine("Unterminated YAML frontmatter.");
+    return 1;
+}
+
+string yaml = frontmatterMatch.Groups["yaml"].Value.Trim();
+
+IDeserializer deserializer = new DeserializerBuilder().Build();
+Dictionary<string, object> frontmatter = deserializer.Deserialize<Dictionary<string, object>>(yaml);
+
+// name is required
+if (!frontmatter.TryGetValue("name", out object? nameValue) || nameValue is not string frontmatterName)
+{
+    Console.Error.WriteLine("Frontmatter missing 'name' field.");
+    return 1;
+}
+
+// name must be 1-64 characters
+if (frontmatterName.Length == 0 || frontmatterName.Length > 64)
+{
+    Console.Error.WriteLine($"Name is {frontmatterName.Length} chars (must be 1-64).");
+    return 1;
+}
+
+// name: lowercase alphanumeric and hyphens only, no leading/trailing/consecutive hyphens
+if (!Regex.IsMatch(frontmatterName, @"^[a-z0-9]([a-z0-9-]*[a-z0-9])?$")
+    || frontmatterName.Contains("--"))
+{
+    Console.Error.WriteLine($"Invalid name '{frontmatterName}'. Must be lowercase letters, numbers, and hyphens only. Must not start/end with a hyphen or contain consecutive hyphens.");
+    return 1;
+}
+
+// name must match the parent directory name
+if (!string.Equals(skillName, frontmatterName, StringComparison.Ordinal))
+{
+    Console.Error.WriteLine($"Name mismatch: directory is '{skillName}' but SKILL.md name is '{frontmatterName}'.");
+    return 1;
+}
+
+// description is required
+if (!frontmatter.TryGetValue("description", out object? descValue) || descValue is not string description)
+{
+    Console.Error.WriteLine("Frontmatter missing 'description' field.");
+    return 1;
+}
+
+// description must be 1-1024 characters
+if (description.Length == 0 || description.Length > 1024)
+{
+    Console.Error.WriteLine($"Description is {description.Length} chars (must be 1-1024).");
+    return 1;
+}
+
+// Keep SKILL.md under 500 lines; move detailed content to references/ or scripts/
+// See "Progressive Disclosure" at https://agentskills.io/specification.md
+int lineCount = text.Split('\n').Length;
+if (lineCount > 500)
+{
+    Console.Error.WriteLine($"SKILL.md is {lineCount} lines (max 500). See \"Progressive Disclosure\" at https://agentskills.io/specification.md");
+    return 1;
+}
+
+Console.WriteLine($"Skill '{frontmatterName}' is valid.");
+return 0;