Add a skill for flake analysis (#187530)

Example output for issue
https://github.com/flutter/flutter/issues/185070

# Flake Analysis Report: `android_engine_vulkan_tests`

This report analyzes the failures of the `android_engine_vulkan_tests`
shard in the `flutter/flutter` repository across 15 recent failed builds
between Build 1658 and Build 2495.

---

## Executive Summary

The failures in the `android_engine_vulkan_tests` builder fall into
three distinct categories:
1. **Primary Blocker (Skia Gold Image Mismatch)**: A
deterministic/semi-deterministic failure where 5 different integration
tests all output the **exact same** image digest
(`5ba6df7acef516f7dab78587cf30ce20`). This strongly points to a frame
buffer rendering or screenshot capture failure (e.g., capturing a
completely blank, black, or transparent frame) on the Vulkan emulator.
2. **Infrastructure / Emulator Issues (Transient Flakes)**: Classical
ADB/emulator connection issues, such as failing to uninstall/install the
application APK, or failure to initialize the native driver wrapper.
3. **Timeout / Aborted Runs**: Builds that failed during the test
execution without printing any specific stdout failure details before
termination, indicating runner-level timeouts.

---

## Build Failure Summary Table

| Build Number | Failure Category | Details / Primary Failure Symptom |
|---|---|---|
| **2495** | Skia Gold Mismatch | All 5 tests matched hash
`5ba6df7acef516f7dab78587cf30ce20` |
| **2392** | Timeout / Aborted | Shard failed without specific error
logs |
| **2337** | Infrastructure | `Failed to uninstall app` (Process exited
abnormally) |
| **2317** | Infrastructure | `Failed to uninstall app` (Process exited
abnormally) |
| **2313** | Skia Gold Mismatch | All 5 tests matched hash
`5ba6df7acef516f7dab78587cf30ce20` |
| **2283** | Infrastructure | `Failed to uninstall app` (Process exited
abnormally) |
| **2280** | Infrastructure | `Failed to uninstall app` (Process exited
abnormally) |
| **2268** | Infrastructure | `Failed to uninstall app`, `nativeDriver
has not been initialized` |
| **2198** | Infrastructure | `Failed to uninstall app`, `Failed to
fulfill WaitFor due to remote error` |
| **1965** | Skia Gold Mismatch | All 5 tests matched hash
`5ba6df7acef516f7dab78587cf30ce20` |
| **1857** | Timeout / Aborted | Shard failed without specific error
logs |
| **1813** | Skia Gold Mismatch | All 5 tests matched hash
`5ba6df7acef516f7dab78587cf30ce20` |
| **1810** | Timeout / Aborted | Shard failed without specific error
logs |
| **1691** | Skia Gold Mismatch | All 5 tests matched hash
`5ba6df7acef516f7dab78587cf30ce20` |
| **1658** | Skia Gold Mismatch | All 5 tests matched hash
`5ba6df7acef516f7dab78587cf30ce20` |

---

## Detailed Findings

### 1. Skia Gold Image Mismatch (Primary Blocker)
In builds **2495, 2313, 1965, 1813, 1691, and 1658**, the following 5
tests failed because the screenshot captured during the test did not
match any approved golden image:
*
`android_engine_test.vulkan.external_texture_surface_texture_smiley_face`
*
`android_engine_test.vulkan.external_texture_surface_producer_smiley_face`
* `android_engine_test.vulkan.platform_view_tap_color_change_initial`
* `android_engine_test.vulkan.fluttered_rendered_blue_rectangle`
*
`android_engine_test.vulkan.texture_layer_hybrid_composition_platform_view.blue_orange_gradient_portrait`

> [!IMPORTANT]
> **Identical Hash Anomaly:**
> For all 5 tests, the screenshot captured had the exact same hash:
`5ba6df7acef516f7dab78587cf30ce20`.
> Since these tests render completely different UI components (e.g. a
blue rectangle vs. a blue/orange gradient vs. a smiley face texture), it
is mathematically impossible for them to produce the same valid image
digest. This indicates that the screenshot capture mechanism (or the
emulator's Vulkan rendering context) returned a blank, black, or
default-cleared buffer.

### 2. Infrastructure / Emulator Issues (Transient Flakes)
In builds **2337, 2317, 2283, 2280, 2268, and 2198**, the tests failed
due to VM/emulator communication errors:
* **ADB Failures:** Logs show `Failed to uninstall app` followed by
`Process exited abnormally with exit code 1`.
* **Driver Failures:** In build 2268, the runner output `Local
'nativeDriver' has not been initialized` and `Failed to fulfill
NativeCommand due to remote error`.
* **Wait Failures:** In build 2198, the runner output `Failed to fulfill
WaitFor due to remote error`.

These are standard emulator health and connectivity flakes, where the
test runner loses connection to the emulator device during apk
installation/uninstallation or command dispatch.

---

## Recommendations & Next Steps

1. **Verify Vulkan Screenshot/Buffer Capture:**
Investigate if the screenshotting code in the Flutter Driver / engine
Vulkan integration tests is correctly capturing the Vulkan swapchain.
The identical hash suggests a blank/empty frame buffer is being
captured.
2. **Review/Triage on Flutter Gold:**
Check the [Flutter Gold console](https://flutter-gold.skia.org/) for
digest `5ba6df7acef516f7dab78587cf30ce20` to visually confirm if the
images are blank/black.
3. **Emulator Stability Improvements:**
To address the secondary infrastructure failures, consider adding retry
logic for emulator ADB connection, or updating the Android emulator
image version used on the LUCI bots.

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>