diff --git a/.github/agents/pr.md b/.github/agents/pr.md
index b2c6fbe67805..c7d4d8600e12 100644
--- a/.github/agents/pr.md
+++ b/.github/agents/pr.md
@@ -407,7 +407,7 @@ Tests were already verified to FAIL in Phase 2. Gate is a confirmation step:
 Use full verification mode - tests should FAIL without fix, PASS with fix.
 
 ```bash
-pwsh .github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 -Platform android
+pwsh .github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 -Platform android -RequireFullVerification
 ```
 
 ### Expected Output (PR with fix)
diff --git a/.github/skills/verify-tests-fail-without-fix/SKILL.md b/.github/skills/verify-tests-fail-without-fix/SKILL.md
index f0708157e4c5..37f9a649cf0e 100644
--- a/.github/skills/verify-tests-fail-without-fix/SKILL.md
+++ b/.github/skills/verify-tests-fail-without-fix/SKILL.md
@@ -1,89 +1,116 @@
 ---
 name: verify-tests-fail-without-fix
-description: Verifies UI tests catch the bug. Auto-detects mode based on git diff - if fix files exist, verifies FAIL without fix and PASS with fix. If only test files, verifies tests FAIL.
+description: Verifies UI tests catch the bug. Supports two modes - verify failure only (test creation) or full verification (test + fix validation).
 ---
 
 # Verify Tests Fail Without Fix
 
-Verifies UI tests actually catch the issue. **Mode is auto-detected based on git diff.**
+Verifies UI tests actually catch the issue. Supports two workflow modes:
 
-## Usage
+## Mode 1: Verify Failure Only (Test Creation)
+
+Use when **creating tests before writing a fix**:
+- Runs tests to verify they **FAIL** (proving they catch the bug)
+- No fix files required
+- Perfect for test-first development
 
 ```bash
-# Auto-detects everything - just specify platform
+# Auto-detect test filter from changed test files
 pwsh .github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 -Platform android
 
 # With explicit test filter
 pwsh .github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 -Platform ios -TestFilter "Issue33356"
 ```
 
-## Auto-Detection
+## Mode 2: Full Verification (Fix Validation)
+
+Use when **validating both tests and fix**:
+1. **Without fix** - tests should FAIL (bug is present)
+2. **With fix** - tests should PASS (bug is fixed)
+
+```bash
+# Auto-detect everything (recommended)
+pwsh .github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 -Platform android -RequireFullVerification
 
-The script automatically determines the mode:
+# With explicit test filter
+pwsh .github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 -Platform ios -TestFilter "Issue33356" -RequireFullVerification
+```
 
-| Changed Files | Mode | Behavior |
-|---------------|------|----------|
-| Fix files + test files | Full verification | FAIL without fix, PASS with fix |
-| Only test files | Verify failure only | Tests must FAIL (reproduce bug) |
+**Note:** `-RequireFullVerification` ensures the script errors if no fix files are detected, preventing silent fallback to failure-only mode.
 
-**Fix files** = any changed file NOT in test directories
-**Test files** = files in `TestCases.*` directories
+## Requirements
+
+**Verify Failure Only Mode:**
+- Test files in the PR (or working directory)
+
+**Full Verification Mode:**
+- Test files in the PR
+- Fix files in the PR (non-test code changes)
+
+The script auto-detects which mode to use based on whether fix files are present.
 
 ## Expected Output
 
-**Full mode (fix files detected):**
+**Verify Failure Only Mode:**
 ```
 ╔═══════════════════════════════════════════════════════════╗
 ║              VERIFICATION PASSED ✅                       ║
 ╠═══════════════════════════════════════════════════════════╣
-║  - FAIL without fix (as expected)                         ║
-║  - PASS with fix (as expected)                            ║
+║  Tests FAILED as expected!                                ║
+║  This proves the tests correctly reproduce the bug.       ║
 ╚═══════════════════════════════════════════════════════════╝
 ```
 
-**Verify failure only (no fix files):**
+**Full Verification Mode:**
 ```
 ╔═══════════════════════════════════════════════════════════╗
-║         VERIFICATION PASSED ✅                            ║
+║              VERIFICATION PASSED ✅                       ║
 ╠═══════════════════════════════════════════════════════════╣
-║  Tests FAILED as expected (bug is reproduced)             ║
+║  - FAIL without fix (as expected)                         ║
+║  - PASS with fix (as expected)                            ║
 ╚═══════════════════════════════════════════════════════════╝
 ```
 
+## What It Does
+
+**Verify Failure Only Mode (no fix files):**
+1. Fetches base branch from origin (if available)
+2. Auto-detects test classes from changed test files
+3. Runs tests (should FAIL to prove they catch the bug)
+4. Reports result
+
+**Full Verification Mode (fix files detected):**
+1. Fetches base branch from origin to ensure accurate diff
+2. Auto-detects fix files (non-test code) from git diff
+3. Auto-detects test classes from `TestCases.Shared.Tests/*.cs`
+4. Reverts fix files to base branch
+5. Runs tests (should FAIL without fix)
+6. Restores fix files
+7. Runs tests (should PASS with fix)
+8. Reports result
+
 ## Troubleshooting
 
 | Problem | Cause | Solution |
 |---------|-------|----------|
+| No fix files detected | Base branch detection failed or no non-test files changed | Use `-FixFiles` or `-BaseBranch` explicitly |
 | Tests pass without fix | Tests don't detect the bug | Review test assertions, update test |
-| Tests pass (no fix files) | **Test is wrong** | Review test vs issue description, fix test |
+| Tests fail with fix | Fix doesn't work or test is wrong | Review fix implementation |
 | App crashes | Duplicate issue numbers, XAML error | Check device logs |
 | Element not found | Wrong AutomationId, app crashed | Verify IDs match |
 
-## What It Does
-
-**Full mode:**
-1. Auto-detects fix files (non-test code) from git diff
-2. Auto-detects test classes from `TestCases.Shared.Tests/*.cs`
-3. Reverts fix files to base branch
-4. Runs tests (should FAIL without fix)
-5. Restores fix files
-6. Runs tests (should PASS with fix)
-7. Reports result
-
-**Verify Failure Only mode:**
-1. Runs tests once
-2. Verifies they FAIL (bug reproduced)
-3. Reports result
-
 ## Optional Parameters
 
 ```bash
+# Require full verification (fail if no fix files detected) - recommended
+-RequireFullVerification
+
 # Explicit test filter
 -TestFilter "Issue32030|ButtonUITests"
 
 # Explicit fix files  
 -FixFiles @("src/Core/src/File.cs")
 
-# Verify failure only (no fix exists yet)
--VerifyFailureOnly
+# Explicit base branch
+-BaseBranch "main"
 ```
diff --git a/.github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1 b/.github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1
index 5aa8b570ab8e..8250d5314b86 100644
--- a/.github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1
+++ b/.github/skills/verify-tests-fail-without-fix/scripts/verify-tests-fail.ps1
@@ -1,22 +1,23 @@
 #!/usr/bin/env pwsh
 <#
 .SYNOPSIS
-    Verifies that UI tests catch the bug. Auto-detects mode based on whether fix files exist.
+    Verifies that UI tests catch the bug. Supports two modes: verify failure only or full verification.
 
 .DESCRIPTION
-    This script verifies that tests actually catch the issue. It auto-detects the mode:
+    This script verifies that tests actually catch the issue. It supports two modes:
     
-    **If fix files exist (non-test code changed):**
-    - Full verification mode
-    - Reverts fix files to base branch
-    - Runs tests WITHOUT fix (should FAIL)
-    - Restores fix files
-    - Runs tests WITH fix (should PASS)
+    VERIFY FAILURE ONLY MODE (no fix files detected):
+    - Runs tests to verify they FAIL (proving they catch the bug)
+    - Used when creating tests before writing a fix
     
-    **If only test files changed (no fix files):**
-    - Verify failure only mode
-    - Runs tests once expecting them to FAIL
-    - Confirms tests reproduce the bug
+    FULL VERIFICATION MODE (fix files detected):
+    1. Reverting fix files to base branch
+    2. Running tests WITHOUT fix (should FAIL)
+    3. Restoring fix files
+    4. Running tests WITH fix (should PASS)
+    
+    The script auto-detects which mode to use based on whether fix files are present.
+    Fix files and test filters are auto-detected from the git diff (non-test files that changed).
 
 .PARAMETER Platform
     Target platform: "android" or "ios"
@@ -27,7 +28,7 @@
 
 .PARAMETER FixFiles
     (Optional) Array of file paths to revert. If not provided, auto-detects from git diff
-    by excluding test directories.
+    by excluding test directories. If no fix files are found, runs in verify failure only mode.
 
 .PARAMETER BaseBranch
     Branch to revert files from. Auto-detected from PR if not specified.
@@ -35,12 +36,21 @@
 .PARAMETER OutputDir
     Directory to store results (default: "CustomAgentLogsTmp/TestValidation")
 
+.PARAMETER RequireFullVerification
+    If set, the script will fail if it cannot run full verification mode
+    (i.e., if no fix files are detected). Without this flag, the script will
+    automatically run in verify failure only mode when no fix files are found.
+
 .EXAMPLE
-    # Auto-detect everything - simplest usage
+    # Verify failure only mode - tests should fail (test creation workflow)
     ./verify-tests-fail.ps1 -Platform android
 
 .EXAMPLE
-    # Specify test filter, auto-detect mode and fix files
+    # Full verification mode - require fix files to be present
+    ./verify-tests-fail.ps1 -Platform android -RequireFullVerification
+
+.EXAMPLE
+    # Specify test filter explicitly (works in both modes)
     ./verify-tests-fail.ps1 -Platform android -TestFilter "Issue32030"
 
 .EXAMPLE
@@ -64,7 +74,10 @@ param(
     [string]$BaseBranch,
 
     [Parameter(Mandatory = $false)]
-    [string]$OutputDir = "CustomAgentLogsTmp/TestValidation"
+    [string]$OutputDir = "CustomAgentLogsTmp/TestValidation",
+
+    [Parameter(Mandatory = $false)]
+    [switch]$RequireFullVerification
 )
 
 $ErrorActionPreference = "Stop"
@@ -88,7 +101,7 @@ $TestPathPatterns = @(
 # Function to check if a file should be excluded from fix files
 function Test-IsTestFile {
     param([string]$FilePath)
-    
+
     foreach ($pattern in $TestPathPatterns) {
         if ($FilePath -like $pattern) {
             return $true
@@ -98,116 +111,390 @@ function Test-IsTestFile {
 }
 
 # ============================================================
-# AUTO-DETECT MODE: Check if there are fix files to revert
+# Find the merge-base commit (where current branch diverged from base)
+# This is more robust than tracking branch names/refs
+# For fork workflows: fetches directly from the PR's target repo URL
+# so it works even if the fork's main branch is out of sync
 # ============================================================
+function Find-MergeBase {
+    param([string]$ExplicitBaseBranch)
+
+    # 1. If explicit base branch provided, use it directly
+    if ($ExplicitBaseBranch) {
+        # Try with origin/ prefix first, then without
+        foreach ($ref in @("origin/$ExplicitBaseBranch", $ExplicitBaseBranch)) {
+            $mergeBase = git merge-base HEAD $ref 2>$null
+            if ($mergeBase) {
+                return @{ MergeBase = $mergeBase; BaseBranch = $ExplicitBaseBranch; Source = "explicit" }
+            }
+        }
+    }
 
-# Try to detect base branch
-$BaseBranchDetected = $BaseBranch
-if (-not $BaseBranchDetected) {
-    $currentBranch = git rev-parse --abbrev-ref HEAD 2>$null
-    $remote = git config "branch.$currentBranch.remote" 2>$null
-    if (-not $remote) { $remote = "origin" }
-    
-    $remoteUrl = git remote get-url $remote 2>$null
-    $repo = $null
-    if ($remoteUrl -match "github\.com[:/]([^/]+/[^/]+?)(\.git)?$") {
-        $repo = $matches[1]
+    # 2. Try to get PR metadata including the TARGET repository
+    #    This is critical for fork workflows where origin points to the fork,
+    #    not the upstream repo. We fetch directly from the target repo URL.
+    #    The PR URL contains the target repo: https://github.com/OWNER/REPO/pull/123
+    $prJson = gh pr view --json baseRefName,url 2>$null
+    if ($prJson) {
+        $prInfo = $prJson | ConvertFrom-Json
+        $prBaseBranch = $prInfo.baseRefName
+        $prUrl = $prInfo.url
+
+        # Parse owner/repo from PR URL: https://github.com/OWNER/REPO/pull/123
+        $targetOwner = $null
+        $targetRepo = $null
+        if ($prUrl -match "github\.com/([^/]+)/([^/]+)/pull/") {
+            $targetOwner = $matches[1]
+            $targetRepo = $matches[2]
+        }
+
+        if ($prBaseBranch -and $targetOwner -and $targetRepo) {
+            # Construct the target repo URL and fetch directly from it
+            # This works even if the developer hasn't set up an 'upstream' remote
+            # and even if their fork's main is completely out of sync
+            $targetUrl = "https://github.com/$targetOwner/$targetRepo.git"
+            Write-Host "ℹ️  PR targets $targetOwner/$targetRepo - fetching $prBaseBranch from upstream..." -ForegroundColor Cyan
+            git fetch $targetUrl $prBaseBranch 2>$null
+
+            if ($LASTEXITCODE -eq 0) {
+                # FETCH_HEAD now points to the target repo's base branch
+                $mergeBase = git merge-base HEAD FETCH_HEAD 2>$null
+                if ($mergeBase) {
+                    return @{ MergeBase = $mergeBase; BaseBranch = $prBaseBranch; Source = "pr-target-repo"; TargetRepo = "$targetOwner/$targetRepo" }
+                }
+            }
+        }
+
+        # Fallback: try fetching from origin (works if origin IS the target repo)
+        if ($prBaseBranch) {
+            git fetch origin $prBaseBranch 2>$null
+            foreach ($ref in @("origin/$prBaseBranch", $prBaseBranch)) {
+                $mergeBase = git merge-base HEAD $ref 2>$null
+                if ($mergeBase) {
+                    return @{ MergeBase = $mergeBase; BaseBranch = $prBaseBranch; Source = "pr-metadata" }
+                }
+            }
+        }
     }
-    
-    if ($repo) {
-        $BaseBranchDetected = gh pr view $currentBranch --repo $repo --json baseRefName --jq '.baseRefName' 2>$null
-    } else {
-        $BaseBranchDetected = gh pr view --json baseRefName --jq '.baseRefName' 2>$null
+
+    # 3. Fallback: Find closest merge-base among common base branch patterns
+    #    The "correct" base is the one with fewest commits between merge-base and HEAD
+    Write-Host "ℹ️  No PR detected, scanning remote branches for closest base..." -ForegroundColor Cyan
+
+    # Fetch all remote refs to ensure we have latest
+    git fetch origin 2>$null
+
+    # Get remote branches matching common base branch patterns
+    $remoteBranches = git branch -r --format='%(refname:short)' 2>$null | Where-Object {
+        $_ -match '^origin/(main|master|net\d+\.\d+|release/.*)$'
     }
+
+    $bestMatch = $null
+    $shortestDistance = [int]::MaxValue
+
+    foreach ($branch in $remoteBranches) {
+        $mergeBase = git merge-base HEAD $branch 2>$null
+        if ($mergeBase) {
+            $distance = [int](git rev-list --count "$mergeBase..HEAD" 2>$null)
+            if ($distance -lt $shortestDistance) {
+                $shortestDistance = $distance
+                $branchName = $branch -replace '^origin/', ''
+                $bestMatch = @{ MergeBase = $mergeBase; BaseBranch = $branchName; Source = "closest-merge-base"; Distance = $distance }
+            }
+        }
+    }
+
+    return $bestMatch
 }
 
-# Check for fix files (non-test files that changed)
-$DetectedFixFiles = @()
-if ($BaseBranchDetected) {
-    $changedFiles = git diff $BaseBranchDetected HEAD --name-only 2>$null
-    if ($LASTEXITCODE -ne 0) {
-        $changedFiles = git diff "origin/$BaseBranchDetected" HEAD --name-only 2>$null
+# ============================================================
+# Auto-detect test filter from changed files
+# ============================================================
+function Get-AutoDetectedTestFilter {
+    param([string]$MergeBase)
+
+    $changedFiles = @()
+    if ($MergeBase) {
+        $changedFiles = git diff $MergeBase HEAD --name-only 2>$null
     }
-    
-    if ($changedFiles) {
-        foreach ($file in $changedFiles) {
-            if (-not (Test-IsTestFile $file)) {
-                $DetectedFixFiles += $file
+
+    # If no merge-base, use git status to find unstaged/staged files
+    if (-not $changedFiles -or $changedFiles.Count -eq 0) {
+        $changedFiles = git diff --name-only 2>$null
+        if (-not $changedFiles -or $changedFiles.Count -eq 0) {
+            $changedFiles = git diff --cached --name-only 2>$null
+        }
+    }
+
+    # Find test files (files in test directories that are .cs files)
+    $testFiles = @()
+    foreach ($file in $changedFiles) {
+        if ($file -match "TestCases\.(Shared\.Tests|HostApp).*\.cs$" -and $file -notmatch "^_") {
+            $testFiles += $file
+        }
+    }
+
+    if ($testFiles.Count -eq 0) {
+        return $null
+    }
+
+    # Extract class names from test files
+    $testClassNames = @()
+    foreach ($file in $testFiles) {
+        if ($file -match "TestCases\.Shared\.Tests.*\.cs$") {
+            $fullPath = Join-Path $RepoRoot $file
+            if (Test-Path $fullPath) {
+                $content = Get-Content $fullPath -Raw
+                if ($content -match "public\s+(partial\s+)?class\s+(\w+)") {
+                    $className = $matches[2]
+                    if ($className -notmatch "^_" -and $testClassNames -notcontains $className) {
+                        $testClassNames += $className
+                    }
+                }
             }
         }
     }
+
+    # Fallback: use file names without extension
+    if ($testClassNames.Count -eq 0) {
+        foreach ($file in $testFiles) {
+            $fileName = [System.IO.Path]::GetFileNameWithoutExtension($file)
+            if ($fileName -notmatch "^_" -and $testClassNames -notcontains $fileName) {
+                $testClassNames += $fileName
+            }
+        }
+    }
+
+    if ($testClassNames.Count -eq 0) {
+        return $null
+    }
+
+    return @{
+        Filter = if ($testClassNames.Count -eq 1) { $testClassNames[0] } else { $testClassNames -join "|" }
+        ClassNames = $testClassNames
+    }
+}
+
+# ============================================================
+# Parse test results from log file
+# ============================================================
+function Get-TestResultFromLog {
+    param([string]$LogFile)
+
+    if (-not (Test-Path $LogFile)) {
+        return @{ Passed = $false; Error = "Test output log not found: $LogFile" }
+    }
+
+    $content = Get-Content $LogFile -Raw
+
+    # Check for failures first - but only if count > 0
+    if ($content -match "Failed:\s*(\d+)") {
+        $failCount = [int]$matches[1]
+        if ($failCount -gt 0) {
+            return @{ Passed = $false; FailCount = $failCount }
+        }
+    }
+
+    # Check for passes
+    if ($content -match "Passed:\s*(\d+)") {
+        $passCount = [int]$matches[1]
+        if ($passCount -gt 0) {
+            return @{ Passed = $true; PassCount = $passCount }
+        }
+    }
+
+    return @{ Passed = $false; Error = "Could not parse test results" }
+}
+
+# ============================================================
+# AUTO-DETECT MODE: Find merge-base and fix files
+# ============================================================
+
+Write-Host ""
+Write-Host "🔍 Detecting base branch and merge point..." -ForegroundColor Cyan
+
+$baseInfo = Find-MergeBase -ExplicitBaseBranch $BaseBranch
+
+if (-not $baseInfo) {
+    Write-Host ""
+    Write-Host "╔═══════════════════════════════════════════════════════════╗" -ForegroundColor Red
+    Write-Host "║         ERROR: COULD NOT FIND MERGE BASE                  ║" -ForegroundColor Red
+    Write-Host "╠═══════════════════════════════════════════════════════════╣" -ForegroundColor Red
+    Write-Host "║  Could not determine where this branch diverged from.     ║" -ForegroundColor Red
+    Write-Host "║                                                           ║" -ForegroundColor Red
+    Write-Host "║  Tried:                                                   ║" -ForegroundColor Red
+    Write-Host "║  - PR metadata (gh pr view)                               ║" -ForegroundColor Red
+    Write-Host "║  - Common base branches (main, net*.0, release/*)         ║" -ForegroundColor Red
+    Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Red
+    Write-Host ""
+    Write-Host "To fix, specify -BaseBranch explicitly:" -ForegroundColor Cyan
+    Write-Host "  ./verify-tests-fail.ps1 -Platform android -BaseBranch main" -ForegroundColor White
+    exit 1
+}
+
+$MergeBase = $baseInfo.MergeBase
+$BaseBranchName = $baseInfo.BaseBranch
+
+if ($baseInfo.TargetRepo) {
+    Write-Host "✅ PR target: $($baseInfo.TargetRepo) ($BaseBranchName branch)" -ForegroundColor Green
+} else {
+    Write-Host "✅ Base branch: $BaseBranchName (via $($baseInfo.Source))" -ForegroundColor Green
+}
+Write-Host "✅ Merge base commit: $($MergeBase.Substring(0, 8))" -ForegroundColor Green
+if ($baseInfo.Distance) {
+    Write-Host "   ($($baseInfo.Distance) commits ahead of $BaseBranchName)" -ForegroundColor Gray
+}
+
+# Check for fix files (non-test files that changed since merge-base)
+$DetectedFixFiles = @()
+$changedFiles = git diff $MergeBase HEAD --name-only 2>$null
+
+if ($changedFiles) {
+    foreach ($file in $changedFiles) {
+        if (-not (Test-IsTestFile $file)) {
+            $DetectedFixFiles += $file
+        }
+    }
 }
 
-# Also check explicitly provided fix files
+# Override with explicitly provided fix files
 if ($FixFiles -and $FixFiles.Count -gt 0) {
     $DetectedFixFiles = $FixFiles
 }
 
-# Determine mode based on whether we have fix files
-$VerifyFailureOnlyMode = ($DetectedFixFiles.Count -eq 0)
+# Error if no fix files detected and RequireFullVerification is set
+if ($DetectedFixFiles.Count -eq 0 -and $RequireFullVerification) {
+    Write-Host ""
+    Write-Host "╔═══════════════════════════════════════════════════════════╗" -ForegroundColor Red
+    Write-Host "║         ERROR: NO FIX FILES DETECTED                      ║" -ForegroundColor Red
+    Write-Host "╠═══════════════════════════════════════════════════════════╣" -ForegroundColor Red
+    Write-Host "║  Full verification mode required but no fix files found.  ║" -ForegroundColor Red
+    Write-Host "║                                                           ║" -ForegroundColor Red
+    Write-Host "║  Possible causes:                                         ║" -ForegroundColor Red
+    Write-Host "║  - No non-test files changed since merge-base             ║" -ForegroundColor Red
+    Write-Host "║  - All changes are in test directories                    ║" -ForegroundColor Red
+    Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Red
+    Write-Host ""
+    Write-Host "Debug info:" -ForegroundColor Yellow
+    Write-Host "  Merge base: $MergeBase" -ForegroundColor Yellow
+    Write-Host "  Base branch: $BaseBranchName" -ForegroundColor Yellow
+    Write-Host "  Current branch: $(git rev-parse --abbrev-ref HEAD)" -ForegroundColor Yellow
+    Write-Host ""
+    Write-Host "To fix, try one of:" -ForegroundColor Cyan
+    Write-Host "  1. Specify fix files explicitly: -FixFiles @('path/to/fix.cs')" -ForegroundColor White
+    Write-Host "  2. Remove -RequireFullVerification to run in failure-only mode" -ForegroundColor White
+    exit 1
+}
 
-# ============================================================
-# VERIFY FAILURE ONLY MODE (no fix files detected)
-# ============================================================
-if ($VerifyFailureOnlyMode) {
+# If no fix files and not requiring full verification, run in "verify failure only" mode
+if ($DetectedFixFiles.Count -eq 0) {
     Write-Host ""
     Write-Host "╔═══════════════════════════════════════════════════════════╗" -ForegroundColor Cyan
     Write-Host "║         VERIFY FAILURE ONLY MODE                          ║" -ForegroundColor Cyan
     Write-Host "╠═══════════════════════════════════════════════════════════╣" -ForegroundColor Cyan
-    Write-Host "║  No fix files detected - verifying tests FAIL             ║" -ForegroundColor Cyan
-    Write-Host "║  (Only test files changed, or new tests created)          ║" -ForegroundColor Cyan
+    Write-Host "║  No fix files detected - will only verify:                ║" -ForegroundColor Cyan
+    Write-Host "║  1. Tests FAIL (proving they catch the bug)               ║" -ForegroundColor Cyan
+    Write-Host "║                                                           ║" -ForegroundColor Cyan
+    Write-Host "║  Use this mode when creating tests before writing a fix.  ║" -ForegroundColor Cyan
     Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Cyan
     Write-Host ""
-    
+
+    # Auto-detect test filter if not provided
     if (-not $TestFilter) {
-        Write-Host "❌ -TestFilter is required when no fix files are detected" -ForegroundColor Red
-        Write-Host "   Example: -TestFilter 'Issue33356'" -ForegroundColor Yellow
-        exit 1
+        Write-Host "🔍 Auto-detecting test filter from changed test files..." -ForegroundColor Cyan
+        $filterResult = Get-AutoDetectedTestFilter -MergeBase $MergeBase
+
+        if (-not $filterResult) {
+            Write-Host "❌ Could not auto-detect test filter. No test files found in changed files." -ForegroundColor Red
+            Write-Host "   Looking for files matching: TestCases.(Shared.Tests|HostApp)/*.cs" -ForegroundColor Yellow
+            Write-Host "   Please provide -TestFilter parameter explicitly." -ForegroundColor Yellow
+            exit 1
+        }
+
+        $TestFilter = $filterResult.Filter
+        Write-Host "✅ Auto-detected $($filterResult.ClassNames.Count) test class(es):" -ForegroundColor Green
+        foreach ($name in $filterResult.ClassNames) {
+            Write-Host "   - $name" -ForegroundColor White
+        }
+        Write-Host "   Filter: $TestFilter" -ForegroundColor Cyan
     }
-    
+
     # Create output directory
     $OutputPath = Join-Path $RepoRoot $OutputDir
     New-Item -ItemType Directory -Force -Path $OutputPath | Out-Null
-    $FailureOnlyLog = Join-Path $OutputPath "verify-failure-only.log"
-    
-    Write-Host "Platform: $Platform" -ForegroundColor White
-    Write-Host "TestFilter: $TestFilter" -ForegroundColor White
+
+    $ValidationLog = Join-Path $OutputPath "verification-log.txt"
+    $TestLog = Join-Path $OutputPath "test-failure-verification.log"
+
+    # Initialize log
+    "" | Set-Content $ValidationLog
+    "=========================================" | Add-Content $ValidationLog
+    "Verify Tests Fail (Failure Only Mode)" | Add-Content $ValidationLog
+    "=========================================" | Add-Content $ValidationLog
+    "Platform: $Platform" | Add-Content $ValidationLog
+    "TestFilter: $TestFilter" | Add-Content $ValidationLog
+    "MergeBase: $MergeBase" | Add-Content $ValidationLog
+    "" | Add-Content $ValidationLog
+
+    Write-Host "🧪 Running tests (expecting them to FAIL)..." -ForegroundColor Cyan
     Write-Host ""
-    Write-Host "Running tests (expecting FAILURE)..." -ForegroundColor Yellow
-    
-    # Run the test
+
+    # Use shared BuildAndRunHostApp.ps1 infrastructure with -Rebuild to ensure clean builds
     $buildScript = Join-Path $RepoRoot ".github/scripts/BuildAndRunHostApp.ps1"
-    & $buildScript -Platform $Platform -TestFilter $TestFilter -Rebuild 2>&1 | Tee-Object -FilePath $FailureOnlyLog
-    
-    # Check test result
+    & $buildScript -Platform $Platform -TestFilter $TestFilter -Rebuild 2>&1 | Tee-Object -FilePath $TestLog
+
+    # Parse test results using shared function
     $testOutputLog = Join-Path $RepoRoot "CustomAgentLogsTmp/UITests/test-output.log"
-    $testFailed = $false
-    
-    if (Test-Path $testOutputLog) {
-        $content = Get-Content $testOutputLog -Raw
-        if ($content -match "Failed:\s*(\d+)" -and [int]$matches[1] -gt 0) {
-            $testFailed = $true
-        }
-    }
-    
+    $testResult = Get-TestResultFromLog -LogFile $testOutputLog
+
+    # Evaluate results
+    Write-Host ""
+    Write-Host "=========================================="
+    Write-Host "VERIFICATION RESULTS"
+    Write-Host "=========================================="
     Write-Host ""
-    if ($testFailed) {
+
+    if ($testResult.Error) {
+        Write-Host "╔═══════════════════════════════════════════════════════════╗" -ForegroundColor Red
+        Write-Host "║              ERROR PARSING TEST RESULTS                   ║" -ForegroundColor Red
+        Write-Host "╠═══════════════════════════════════════════════════════════╣" -ForegroundColor Red
+        Write-Host "║  $($testResult.Error.PadRight(57)) ║" -ForegroundColor Red
+        Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Red
+        exit 1
+    }
+
+    if (-not $testResult.Passed) {
+        # Tests FAILED - this is what we want!
         Write-Host "╔═══════════════════════════════════════════════════════════╗" -ForegroundColor Green
-        Write-Host "║         VERIFICATION PASSED ✅                            ║" -ForegroundColor Green
+        Write-Host "║              VERIFICATION PASSED ✅                       ║" -ForegroundColor Green
         Write-Host "╠═══════════════════════════════════════════════════════════╣" -ForegroundColor Green
-        Write-Host "║  Tests FAILED as expected (bug is reproduced)             ║" -ForegroundColor Green
+        Write-Host "║  Tests FAILED as expected!                                ║" -ForegroundColor Green
         Write-Host "║                                                           ║" -ForegroundColor Green
-        Write-Host "║  Next: Implement a fix, then rerun to verify tests pass.  ║" -ForegroundColor Green
+        Write-Host "║  This proves the tests correctly reproduce the bug.       ║" -ForegroundColor Green
+        Write-Host "║  You can now proceed to write the fix.                    ║" -ForegroundColor Green
         Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Green
+        Write-Host ""
+        Write-Host "Failed tests: $($testResult.FailCount)" -ForegroundColor Yellow
         exit 0
     } else {
+        # Tests PASSED - this is bad!
         Write-Host "╔═══════════════════════════════════════════════════════════╗" -ForegroundColor Red
-        Write-Host "║         VERIFICATION FAILED ❌                            ║" -ForegroundColor Red
+        Write-Host "║              VERIFICATION FAILED ❌                       ║" -ForegroundColor Red
         Write-Host "╠═══════════════════════════════════════════════════════════╣" -ForegroundColor Red
-        Write-Host "║  Tests PASSED (unexpected - bug not reproduced)           ║" -ForegroundColor Red
+        Write-Host "║  Tests PASSED but they should FAIL!                       ║" -ForegroundColor Red
         Write-Host "║                                                           ║" -ForegroundColor Red
-        Write-Host "║  Your test is wrong. Fix it and rerun.                    ║" -ForegroundColor Red
+        Write-Host "║  This means your tests don't actually reproduce the bug.  ║" -ForegroundColor Red
+        Write-Host "║                                                           ║" -ForegroundColor Red
+        Write-Host "║  Possible causes:                                         ║" -ForegroundColor Red
+        Write-Host "║  1. Test scenario doesn't match the issue description     ║" -ForegroundColor Red
+        Write-Host "║  2. Test assertions are wrong or too lenient              ║" -ForegroundColor Red
+        Write-Host "║  3. The bug was already fixed in this branch              ║" -ForegroundColor Red
+        Write-Host "║  4. The bug only happens in specific conditions           ║" -ForegroundColor Red
+        Write-Host "║                                                           ║" -ForegroundColor Red
+        Write-Host "║  Go back and revise your tests!                           ║" -ForegroundColor Red
         Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Red
+        Write-Host ""
+        Write-Host "Passed tests: $($testResult.PassCount)" -ForegroundColor Yellow
         exit 1
     }
 }
@@ -226,10 +513,8 @@ Write-Host "║  2. Tests PASS with fix                                   ║" -
 Write-Host "╚═══════════════════════════════════════════════════════════╝" -ForegroundColor Cyan
 Write-Host ""
 
-$BaseBranch = $BaseBranchDetected
 $FixFiles = $DetectedFixFiles
 
-Write-Host "✅ Base branch: $BaseBranch" -ForegroundColor Green
 Write-Host "✅ Fix files ($($FixFiles.Count)):" -ForegroundColor Green
 foreach ($file in $FixFiles) {
     Write-Host "   - $file" -ForegroundColor White
@@ -238,68 +523,18 @@ foreach ($file in $FixFiles) {
 # Auto-detect test filter from test files if not provided
 if (-not $TestFilter) {
     Write-Host "🔍 Auto-detecting test filter from changed test files..." -ForegroundColor Cyan
-    
-    $changedFiles = git diff $BaseBranch HEAD --name-only 2>$null
-    if ($LASTEXITCODE -ne 0) {
-        $changedFiles = git diff "origin/$BaseBranch" HEAD --name-only 2>$null
-    }
-    
-    # Find test files (files in test directories that are .cs files)
-    $testFiles = @()
-    foreach ($file in $changedFiles) {
-        if ($file -match "TestCases\.(Shared\.Tests|HostApp).*\.cs$" -and $file -notmatch "^_") {
-            $testFiles += $file
-        }
-    }
-    
-    if ($testFiles.Count -eq 0) {
+    $filterResult = Get-AutoDetectedTestFilter -MergeBase $MergeBase
+
+    if (-not $filterResult) {
         Write-Host "❌ Could not auto-detect test filter. No test files found in changed files." -ForegroundColor Red
         Write-Host "   Looking for files matching: TestCases.(Shared.Tests|HostApp)/*.cs" -ForegroundColor Yellow
         Write-Host "   Please provide -TestFilter parameter explicitly." -ForegroundColor Yellow
         exit 1
     }
-    
-    # Extract class names from test files
-    $testClassNames = @()
-    foreach ($file in $testFiles) {
-        if ($file -match "TestCases\.Shared\.Tests.*\.cs$") {
-            $fullPath = Join-Path $RepoRoot $file
-            if (Test-Path $fullPath) {
-                $content = Get-Content $fullPath -Raw
-                if ($content -match "public\s+(partial\s+)?class\s+(\w+)") {
-                    $className = $matches[2]
-                    if ($className -notmatch "^_" -and $testClassNames -notcontains $className) {
-                        $testClassNames += $className
-                    }
-                }
-            }
-        }
-    }
-    
-    # Fallback: use file names without extension
-    if ($testClassNames.Count -eq 0) {
-        foreach ($file in $testFiles) {
-            $fileName = [System.IO.Path]::GetFileNameWithoutExtension($file)
-            if ($fileName -notmatch "^_" -and $testClassNames -notcontains $fileName) {
-                $testClassNames += $fileName
-            }
-        }
-    }
-    
-    if ($testClassNames.Count -eq 0) {
-        Write-Host "❌ Could not extract test class names from changed files." -ForegroundColor Red
-        Write-Host "   Please provide -TestFilter parameter explicitly." -ForegroundColor Yellow
-        exit 1
-    }
-    
-    if ($testClassNames.Count -eq 1) {
-        $TestFilter = $testClassNames[0]
-    } else {
-        $TestFilter = $testClassNames -join "|"
-    }
-    
-    Write-Host "✅ Auto-detected $($testClassNames.Count) test class(es):" -ForegroundColor Green
-    foreach ($name in $testClassNames) {
+
+    $TestFilter = $filterResult.Filter
+    Write-Host "✅ Auto-detected $($filterResult.ClassNames.Count) test class(es):" -ForegroundColor Green
+    foreach ($name in $filterResult.ClassNames) {
         Write-Host "   - $name" -ForegroundColor White
     }
     Write-Host "   Filter: $TestFilter" -ForegroundColor Cyan
@@ -321,20 +556,7 @@ function Write-Log {
     Add-Content -Path $ValidationLog -Value $logLine
 }
 
-function Get-TestResult {
-    param([string]$LogFile)
-
-    if (Test-Path $LogFile) {
-        $content = Get-Content $LogFile -Raw
-        if ($content -match "Failed:\s*(\d+)") {
-            return @{ Passed = $false; FailCount = [int]$matches[1] }
-        }
-        if ($content -match "Passed:\s*(\d+)") {
-            return @{ Passed = $true; PassCount = [int]$matches[1] }
-        }
-    }
-    return @{ Passed = $false; Error = "Could not parse test results" }
-}
+# Reuse the Get-TestResultFromLog function defined earlier
 
 # Initialize log
 "" | Set-Content $ValidationLog
@@ -344,7 +566,8 @@ Write-Log "=========================================="
 Write-Log "Platform: $Platform"
 Write-Log "TestFilter: $TestFilter"
 Write-Log "FixFiles: $($FixFiles -join ', ')"
-Write-Log "BaseBranch: $BaseBranch"
+Write-Log "BaseBranch: $BaseBranchName"
+Write-Log "MergeBase: $MergeBase"
 Write-Log ""
 
 # Verify fix files exist
@@ -358,22 +581,19 @@ foreach ($file in $FixFiles) {
     Write-Log "  ✓ $file exists"
 }
 
-# Determine which files exist in the base branch (can be reverted)
+# Determine which files exist at the merge-base (can be reverted)
 Write-Log ""
-Write-Log "Checking which fix files exist in $BaseBranch..."
+Write-Log "Checking which fix files exist at merge-base ($($MergeBase.Substring(0, 8)))..."
 $RevertableFiles = @()
 $NewFiles = @()
 
 foreach ($file in $FixFiles) {
-    # Check if file exists in base branch
-    $existsInBase = git ls-tree -r $BaseBranch --name-only -- $file 2>$null
-    if (-not $existsInBase) {
-        $existsInBase = git ls-tree -r "origin/$BaseBranch" --name-only -- $file 2>$null
-    }
-    
+    # Check if file exists at merge-base commit
+    $existsInBase = git ls-tree -r $MergeBase --name-only -- $file 2>$null
+
     if ($existsInBase) {
         $RevertableFiles += $file
-        Write-Log "  ✓ $file (exists in $BaseBranch - will revert)"
+        Write-Log "  ✓ $file (exists at merge-base - will revert)"
     } else {
         $NewFiles += $file
         Write-Log "  ○ $file (new file - skipping revert)"
@@ -418,22 +638,22 @@ if ($uncommittedFiles.Count -gt 0) {
 
 Write-Log "  ✓ All revertable fix files are committed"
 
-# Step 1: Revert fix files to base branch
+# Step 1: Revert fix files to merge-base state
 Write-Log ""
 Write-Log "=========================================="
-Write-Log "STEP 1: Reverting fix files to $BaseBranch"
+Write-Log "STEP 1: Reverting fix files to merge-base ($($MergeBase.Substring(0, 8)))"
 Write-Log "=========================================="
 
 foreach ($file in $RevertableFiles) {
     Write-Log "  Reverting: $file"
-    git checkout $BaseBranch -- $file 2>&1 | Out-Null
+    git checkout $MergeBase -- $file 2>&1 | Out-Null
     if ($LASTEXITCODE -ne 0) {
-        Write-Log "  Warning: Could not revert from $BaseBranch, trying origin/$BaseBranch"
-        git checkout "origin/$BaseBranch" -- $file 2>&1 | Out-Null
+        Write-Log "  ERROR: Failed to revert $file from $MergeBase"
+        exit 1
     }
 }
 
-Write-Log "  ✓ $($RevertableFiles.Count) fix file(s) reverted to $BaseBranch state"
+Write-Log "  ✓ $($RevertableFiles.Count) fix file(s) reverted to merge-base state"
 
 # Step 2: Run tests WITHOUT fix
 Write-Log ""
@@ -445,7 +665,7 @@ Write-Log "=========================================="
 $buildScript = Join-Path $RepoRoot ".github/scripts/BuildAndRunHostApp.ps1"
 & $buildScript -Platform $Platform -TestFilter $TestFilter -Rebuild 2>&1 | Tee-Object -FilePath $WithoutFixLog
 
-$withoutFixResult = Get-TestResult -LogFile (Join-Path $RepoRoot "CustomAgentLogsTmp/UITests/test-output.log")
+$withoutFixResult = Get-TestResultFromLog -LogFile (Join-Path $RepoRoot "CustomAgentLogsTmp/UITests/test-output.log")
 
 # Step 3: Restore fix files from current branch HEAD
 Write-Log ""
@@ -472,7 +692,7 @@ Write-Log "=========================================="
 
 & $buildScript -Platform $Platform -TestFilter $TestFilter -Rebuild 2>&1 | Tee-Object -FilePath $WithFixLog
 
-$withFixResult = Get-TestResult -LogFile (Join-Path $RepoRoot "CustomAgentLogsTmp/UITests/test-output.log")
+$withFixResult = Get-TestResultFromLog -LogFile (Join-Path $RepoRoot "CustomAgentLogsTmp/UITests/test-output.log")
 
 # Step 5: Evaluate results
 Write-Log ""