diff --git a/.github/instructions/build-checkout-prerequisites.instructions.md b/.github/instructions/build-checkout-prerequisites.instructions.md
new file mode 100644
index 0000000000..717aa6faa3
--- /dev/null
+++ b/.github/instructions/build-checkout-prerequisites.instructions.md
@@ -0,0 +1,148 @@
+---
+applyTo:
+  - ".github/**/*.yml"
+  - ".github/**/*.yaml"
+---
+
+# Build and Checkout Prerequisites for PowerShell CI
+
+This document describes the checkout and build prerequisites used in PowerShell's CI workflows. It is intended for GitHub Copilot sessions working with the build system.
+
+## Overview
+
+The PowerShell repository uses a standardized build process across Linux, Windows, and macOS CI workflows. Understanding the checkout configuration and the `Sync-PSTags` operation is crucial for working with the build system.
+
+## Checkout Configuration
+
+### Fetch Depth
+
+All CI workflows that build or test PowerShell use `fetch-depth: 1000` in the checkout step:
+
+```yaml
+- name: checkout
+  uses: actions/checkout@v5
+  with:
+    fetch-depth: 1000
+```
+
+**Why 1000 commits?**
+- The build system needs access to Git history to determine version information
+- `Sync-PSTags` requires sufficient history to fetch and work with tags
+- 1000 commits provides a reasonable balance between clone speed and having enough history for version calculation
+- Shallow clones (fetch-depth: 1) would break versioning logic
+
+**Exceptions:**
+- The `changes` job uses default fetch depth (no explicit `fetch-depth`) since it only needs to detect file changes
+- The `analyze` job (CodeQL) uses `fetch-depth: '0'` (full history) for comprehensive security analysis
+- Linux packaging uses `fetch-depth: 0` to ensure all tags are available for package version metadata
+
+### Workflows Using fetch-depth: 1000
+
+- **Linux CI** (`.github/workflows/linux-ci.yml`): All build and test jobs
+- **Windows CI** (`.github/workflows/windows-ci.yml`): All build and test jobs  
+- **macOS CI** (`.github/workflows/macos-ci.yml`): All build and test jobs
+
+## Sync-PSTags Operation
+
+### What is Sync-PSTags?
+
+`Sync-PSTags` is a PowerShell function defined in `build.psm1` that ensures Git tags from the upstream PowerShell repository are synchronized to the local clone.
+
+### Location
+
+- **Function Definition**: `build.psm1` (line 36-76)
+- **Called From**: 
+  - `.github/actions/build/ci/action.yml` (Bootstrap step, line 24)
+  - `tools/ci.psm1` (Invoke-CIInstall function, line 146)
+
+### How It Works
+
+```powershell
+Sync-PSTags -AddRemoteIfMissing
+```
+
+The function:
+1. Searches for a Git remote pointing to the official PowerShell repository:
+   - `https://github.com/PowerShell/PowerShell`
+   - `git@github.com:PowerShell/PowerShell`
+
+2. If no upstream remote exists and `-AddRemoteIfMissing` is specified:
+   - Adds a remote named `upstream` pointing to `https://github.com/PowerShell/PowerShell.git`
+
+3. Fetches all tags from the upstream remote:
+   ```bash
+   git fetch --tags --quiet upstream
+   ```
+
+4. Sets `$script:tagsUpToDate = $true` to indicate tags are synchronized
+
+### Why Sync-PSTags is Required
+
+Tags are critical for:
+- **Version Calculation**: `Get-PSVersion` uses `git describe --abbrev=0` to find the latest tag
+- **Build Numbering**: CI builds use tag-based versioning for artifacts
+- **Changelog Generation**: Release notes are generated based on tags
+- **Package Metadata**: Package versions are derived from Git tags
+
+Without synchronized tags:
+- Version detection would fail or return incorrect versions
+- Builds might have inconsistent version numbers
+- The build process would error when trying to determine the version
+
+### Bootstrap Step in CI Action
+
+The `.github/actions/build/ci/action.yml` includes this in the Bootstrap step:
+
+```yaml
+- name: Bootstrap
+  if: success()
+  run: |-
+    Write-Verbose -Verbose "Running Bootstrap..."
+    Import-Module .\tools\ci.psm1
+    Invoke-CIInstall -SkipUser
+    Write-Verbose -Verbose "Start Sync-PSTags"
+    Sync-PSTags -AddRemoteIfMissing
+    Write-Verbose -Verbose "End Sync-PSTags"
+  shell: pwsh
+```
+
+**Note**: `Sync-PSTags` is called twice:
+1. Once by `Invoke-CIInstall` (in `tools/ci.psm1`)
+2. Explicitly again in the Bootstrap step
+
+This redundancy ensures tags are available even if the first call encounters issues.
+
+## Best Practices for Copilot Sessions
+
+When working with the PowerShell CI system:
+
+1. **Always use `fetch-depth: 1000` or greater** when checking out code for build or test operations
+2. **Understand that `Sync-PSTags` requires network access** to fetch tags from the upstream repository
+3. **Don't modify the fetch-depth without understanding the impact** on version calculation
+4. **If adding new CI workflows**, follow the existing pattern:
+   - Use `fetch-depth: 1000` for build/test jobs
+   - Call `Sync-PSTags -AddRemoteIfMissing` during bootstrap
+   - Ensure the upstream remote is properly configured
+
+5. **For local development**, developers should:
+   - Have the upstream remote configured
+   - Run `Sync-PSTags -AddRemoteIfMissing` before building
+   - Or use `Start-PSBuild` which handles this automatically
+
+## Related Files
+
+- `.github/actions/build/ci/action.yml` - Main CI build action
+- `.github/workflows/linux-ci.yml` - Linux CI workflow
+- `.github/workflows/windows-ci.yml` - Windows CI workflow
+- `.github/workflows/macos-ci.yml` - macOS CI workflow
+- `build.psm1` - Contains Sync-PSTags function definition
+- `tools/ci.psm1` - CI-specific build functions that call Sync-PSTags
+
+## Summary
+
+The PowerShell CI system depends on:
+1. **Adequate Git history** (fetch-depth: 1000) for version calculation
+2. **Synchronized Git tags** via `Sync-PSTags` for accurate versioning
+3. **Upstream remote access** to fetch official repository tags
+
+These prerequisites ensure consistent, accurate build versioning across all CI platforms.
diff --git a/.github/instructions/build-configuration-guide.md b/.github/instructions/build-configuration-guide.instructions.md
similarity index 94%
rename from .github/instructions/build-configuration-guide.md
rename to .github/instructions/build-configuration-guide.instructions.md
index d082bcbe77..848aacef49 100644
--- a/.github/instructions/build-configuration-guide.md
+++ b/.github/instructions/build-configuration-guide.instructions.md
@@ -1,3 +1,11 @@
+---
+applyTo:
+  - "build.psm1"
+  - "tools/ci.psm1"
+  - ".github/**/*.yml"
+  - ".github/**/*.yaml"
+---
+
 # Build Configuration Guide
 
 ## Choosing the Right Configuration
diff --git a/.github/instructions/git-requirements-for-builds.md b/.github/instructions/git-requirements-for-builds.md
deleted file mode 100644
index 3c8cd91e7c..0000000000
--- a/.github/instructions/git-requirements-for-builds.md
+++ /dev/null
@@ -1,71 +0,0 @@
-# Git Requirements for Building PowerShell
-
-## Fetch Depth
-
-**Required:** `fetch-depth: 1000`
-
-The PowerShell build process uses `git describe --abbrev=60 --long` to generate version information. This requires access to git history and tags.
-
-### Problem
-
-Without sufficient fetch depth, builds fail with:
-```
-error MSB3073: The command "git describe --abbrev=60 --long" exited with code 128.
-```
-
-### Solution
-
-Always use `fetch-depth: 1000` in the checkout step:
-
-```yaml
-- name: Checkout
-  uses: actions/checkout@v4
-  with:
-    fetch-depth: 1000
-```
-
-## Tag Synchronization
-
-**Required:** `Sync-PSTags -AddRemoteIfMissing`
-
-The build process needs git tags to properly version the build.
-
-### Problem
-
-Without tag synchronization:
-- Version information is incorrect
-- Build versioning fails
-
-### Solution
-
-Include tag synchronization in the bootstrap step:
-
-```yaml
-- name: Bootstrap
-  shell: pwsh
-  run: |
-    Import-Module ./tools/ci.psm1
-    Sync-PSTags -AddRemoteIfMissing
-```
-
-## Complete Example
-
-```yaml
-steps:
-  - name: Checkout
-    uses: actions/checkout@v4
-    with:
-      fetch-depth: 1000
-
-  - name: Setup .NET
-    uses: actions/setup-dotnet@v4
-    with:
-      global-json-file: ./global.json
-
-  - name: Bootstrap
-    shell: pwsh
-    run: |
-      Import-Module ./tools/ci.psm1
-      Invoke-CIInstall -SkipUser
-      Sync-PSTags -AddRemoteIfMissing
-```
diff --git a/.github/instructions/instruction-file-format.instructions.md b/.github/instructions/instruction-file-format.instructions.md
new file mode 100644
index 0000000000..7c4e0bdd13
--- /dev/null
+++ b/.github/instructions/instruction-file-format.instructions.md
@@ -0,0 +1,220 @@
+---
+applyTo:
+  - ".github/instructions/**/*.instructions.md"
+---
+
+# Instruction File Format Guide
+
+This document describes the format and guidelines for creating custom instruction files for GitHub Copilot in the PowerShell repository.
+
+## File Naming Convention
+
+All instruction files must use the `.instructions.md` suffix:
+- ✅ Correct: `build-checkout-prerequisites.instructions.md`
+- ✅ Correct: `start-psbuild-basics.instructions.md`
+- ❌ Incorrect: `build-guide.md`
+- ❌ Incorrect: `instructions.md`
+
+## Required Frontmatter
+
+Every instruction file must start with YAML frontmatter containing an `applyTo` section:
+
+```yaml
+---
+applyTo:
+  - "path/to/files/**/*.ext"
+  - "specific-file.ext"
+---
+```
+
+### applyTo Patterns
+
+Specify which files or directories these instructions apply to:
+
+**For workflow files:**
+```yaml
+applyTo:
+  - ".github/**/*.yml"
+  - ".github/**/*.yaml"
+```
+
+**For build scripts:**
+```yaml
+applyTo:
+  - "build.psm1"
+  - "tools/ci.psm1"
+```
+
+**For multiple contexts:**
+```yaml
+applyTo:
+  - "build.psm1"
+  - "tools/**/*.psm1"
+  - ".github/**/*.yml"
+```
+
+## Content Structure
+
+### 1. Clear Title
+
+Use a descriptive H1 heading after the frontmatter:
+
+```markdown
+# Build Configuration Guide
+```
+
+### 2. Purpose or Overview
+
+Start with a brief explanation of what the instructions cover:
+
+```markdown
+## Purpose
+
+This guide explains how to configure PowerShell builds for different scenarios.
+```
+
+### 3. Actionable Content
+
+Provide clear, actionable guidance:
+
+**✅ Good - Specific and actionable:**
+```markdown
+## Default Usage
+
+Use `Start-PSBuild` with no parameters for testing:
+
+```powershell
+Import-Module ./tools/ci.psm1
+Start-PSBuild
+```
+```
+
+**❌ Bad - Vague and unclear:**
+```markdown
+## Usage
+
+You can use Start-PSBuild to build stuff.
+```
+
+### 4. Code Examples
+
+Include working code examples with proper syntax highlighting:
+
+```markdown
+```yaml
+- name: Build PowerShell
+  shell: pwsh
+  run: |
+    Import-Module ./tools/ci.psm1
+    Start-PSBuild
+```
+```
+
+### 5. Context and Rationale
+
+Explain why things are done a certain way:
+
+```markdown
+**Why fetch-depth: 1000?**
+- The build system needs Git history for version calculation
+- Shallow clones would break versioning logic
+```
+
+## Best Practices
+
+### Be Concise
+
+- Focus on essential information
+- Remove redundant explanations
+- Use bullet points for lists
+
+### Be Specific
+
+- Provide exact commands and parameters
+- Include file paths and line numbers when relevant
+- Show concrete examples, not abstract concepts
+
+### Avoid Duplication
+
+- Don't repeat information from other instruction files
+- Reference other files when appropriate
+- Keep each file focused on one topic
+
+### Use Proper Formatting
+
+**Headers:**
+- Use H1 (`#`) for the main title
+- Use H2 (`##`) for major sections
+- Use H3 (`###`) for subsections
+
+**Code blocks:**
+- Always specify the language: ` ```yaml `, ` ```powershell `, ` ```bash `
+- Keep examples short and focused
+- Test examples before including them
+
+**Lists:**
+- Use `-` for unordered lists
+- Use `1.` for ordered lists
+- Keep list items concise
+
+## Example Structure
+
+```markdown
+---
+applyTo:
+  - "relevant/files/**/*.ext"
+---
+
+# Title of Instructions
+
+Brief description of what these instructions cover.
+
+## Section 1
+
+Content with examples.
+
+```language
+code example
+```
+
+## Section 2
+
+More specific guidance.
+
+### Subsection
+
+Detailed information when needed.
+
+## Best Practices
+
+- Actionable tip 1
+- Actionable tip 2
+```
+
+## Maintaining Instructions
+
+### When to Create a New File
+
+Create a new instruction file when:
+- Covering a distinct topic not addressed elsewhere
+- The content is substantial enough to warrant its own file
+- The `applyTo` scope is different from existing files
+
+### When to Update an Existing File
+
+Update an existing file when:
+- Information is outdated
+- New best practices emerge
+- Examples need correction
+
+### When to Merge or Delete
+
+Merge or delete files when:
+- Content is duplicated across multiple files
+- A file is too small to be useful standalone
+- Information is no longer relevant
+
+## Reference
+
+For more details, see:
+- [GitHub Copilot Custom Instructions Documentation](https://docs.github.com/en/copilot/how-tos/configure-custom-instructions/add-repository-instructions)
diff --git a/.github/instructions/start-psbuild-basics.md b/.github/instructions/start-psbuild-basics.instructions.md
similarity index 93%
rename from .github/instructions/start-psbuild-basics.md
rename to .github/instructions/start-psbuild-basics.instructions.md
index ae216a1584..18a0026eb2 100644
--- a/.github/instructions/start-psbuild-basics.md
+++ b/.github/instructions/start-psbuild-basics.instructions.md
@@ -1,3 +1,11 @@
+---
+applyTo:
+  - "build.psm1"
+  - "tools/ci.psm1"
+  - ".github/**/*.yml"
+  - ".github/**/*.yaml"
+---
+
 # Start-PSBuild Basics
 
 ## Purpose
diff --git a/.github/instructions/troubleshooting-builds.md b/.github/instructions/troubleshooting-builds.instructions.md
similarity index 94%
rename from .github/instructions/troubleshooting-builds.md
rename to .github/instructions/troubleshooting-builds.instructions.md
index 37f5df0091..e9b60cb8c8 100644
--- a/.github/instructions/troubleshooting-builds.md
+++ b/.github/instructions/troubleshooting-builds.instructions.md
@@ -1,3 +1,11 @@
+---
+applyTo:
+  - "build.psm1"
+  - "tools/ci.psm1"
+  - ".github/**/*.yml"
+  - ".github/**/*.yaml"
+---
+
 # Troubleshooting Build Issues
 
 ## Git Describe Error
diff --git a/.github/instructions/workflow-prerequisites.md b/.github/instructions/workflow-prerequisites.md
deleted file mode 100644
index fe88abb384..0000000000
--- a/.github/instructions/workflow-prerequisites.md
+++ /dev/null
@@ -1,91 +0,0 @@
-# Workflow Prerequisites for Building PowerShell
-
-## Required Steps Before Start-PSBuild
-
-These steps must run before calling `Start-PSBuild`:
-
-### 1. Checkout
-
-```yaml
-- name: Checkout
-  uses: actions/checkout@v4
-  with:
-    fetch-depth: 1000  # Required for version generation
-```
-
-### 2. Setup .NET
-
-```yaml
-- name: Setup .NET
-  uses: actions/setup-dotnet@v4
-  with:
-    global-json-file: ./global.json
-```
-
-### 3. Bootstrap
-
-```yaml
-- name: Bootstrap
-  shell: pwsh
-  run: |
-    Import-Module ./tools/ci.psm1
-    Invoke-CIInstall -SkipUser
-    Sync-PSTags -AddRemoteIfMissing
-```
-
-## Complete Prerequisites Example
-
-```yaml
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-        with:
-          fetch-depth: 1000
-
-      - name: Setup .NET
-        uses: actions/setup-dotnet@v4
-        with:
-          global-json-file: ./global.json
-
-      - name: Bootstrap
-        shell: pwsh
-        run: |
-          Import-Module ./tools/ci.psm1
-          Invoke-CIInstall -SkipUser
-          Sync-PSTags -AddRemoteIfMissing
-
-      - name: Build PowerShell
-        shell: pwsh
-        run: |
-          Import-Module ./tools/ci.psm1
-          Start-PSBuild
-```
-
-## Why Each Step Matters
-
-**Checkout with fetch-depth:**
-- Build needs git history for versioning
-- Without it: `git describe` fails
-
-**Setup .NET:**
-- Provides SDK for building
-- Uses version from global.json
-
-**Bootstrap:**
-- Installs dependencies
-- Syncs git tags
-- Prepares build environment
-
-## Optional Steps
-
-### Environment Capture (Debugging)
-
-```yaml
-- name: Capture Environment
-  run: |
-    Get-ChildItem -Path env: | Out-String -width 9999 -Stream | Write-Verbose -Verbose
-  shell: pwsh
-```