Improve verify-tests-fail-without-fix Skill

.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)

.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"
 ```