Add upload-screenshot skill and wire into create-pr

.agents/skills/create-pr/SKILL.md

@@ -14,6 +14,7 @@ This guide covers best practices for creating pull requests in the warp reposito
 - `fix-errors` - Fix presubmit failures (formatting, linting, tests) before opening PR
 - `warp-integration-test` - Add or update integration coverage for user-visible flows, regressions, and P0 use cases
 - `add-feature-flag` - Gate changes behind feature flags
+- `upload-screenshot` - Capture a screenshot with computer use, upload to a stable host, and embed it in the PR description or post to Slack
 
 ## Pre-PR Checklist
 
@@ -213,6 +214,16 @@ Your PR summary under the "Description" section should include:
 2. **Why** - Why these changes are necessary (link to Linear task if applicable)
 3. **How** - Brief explanation of the approach taken
 
+### Visual Evidence for UI Changes
+
+For any change that affects rendered output (layout, colors, borders, new components, rendering bug fixes), include visual evidence in the PR description:
+
+- If the user has explicitly requested a screenshot, or the change is clearly user-visible: use the `upload-screenshot` skill to capture, upload, and embed the image before opening the PR.
+- If ambiguous (e.g. an internal refactor that may have visual side-effects): ask the user — *"This touches [component]. Should I capture a screenshot before opening the PR?"*
+- If the change has no visible output (refactors, logic, CI): skip visual evidence.
+
+Add a `### Screenshots / Videos` section to the PR description with the embedded image(s). See the `upload-screenshot` skill for the upload and embedding workflow.
+
 ## After Opening the PR
 
 1. **Monitor CI checks** - Ensure all automated checks pass

.agents/skills/upload-screenshot/SKILL.md

@@ -0,0 +1,105 @@
+---
+name: upload-screenshot
+description: Upload one or more screenshots to a stable image host and embed them in a GitHub PR description and/or post to a Slack thread. Use when visual evidence of a UI change needs to be attached to a PR or shared in Slack. Works in both local and cloud (sandboxed) environments.
+---
+
+# upload-screenshot
+
+## Overview
+
+Uploads PNG/JPEG screenshots to a stable public image host and returns embeddable URLs. Supports two output targets: updating a GitHub PR description and posting to a Slack thread. Either or both targets can be used in a single invocation.
+
+## Image Hosting
+
+Try hosts in this order, moving to the next on failure:
+
+### 1. Imgur (preferred)
+
+Imgur anonymous upload works reliably from cloud environments without an account.
+
+```bash
+RESPONSE=$(curl -s -X POST \
+  -H "Authorization: Client-ID 546c25a59c58ad7" \
+  -F "image=@/path/to/screenshot.png" \
+  "https://api.imgur.com/3/image")
+
+IMAGE_URL=$(echo "$RESPONSE" | python3 -c "import sys,json; d=json.load(sys.stdin); print(d['data']['link'])")
+echo "$IMAGE_URL"
+```
+
+Check that `IMAGE_URL` starts with `https://i.imgur.com/`. If the response contains `{"success":false,...}` or is empty, fall through to the next host.
+
+### 2. Fallback: upload the image locally and reference it
+
+If external hosting is unavailable, save the image as a conversation artifact using the `upload_artifact` tool (available in Oz agents) and note the limitation in the PR comment.
+
+## Output Target: GitHub PR description
+
+Fetch the current PR body and inject a `### Screenshots / Videos` section before the Agent Mode section (or at the end of the Testing section). Use `gh api` to patch the PR:
+
+```bash
+# Get current body
+CURRENT_BODY=$(gh api repos/{owner}/{repo}/pulls/{pr_number} --jq '.body')
+
+# Append screenshots section (or insert before existing section)
+NEW_BODY="${CURRENT_BODY}
+
+### Screenshots / Videos
+
+![Screenshot](${IMAGE_URL})"
+
+# Patch
+gh api repos/{owner}/{repo}/pulls/{pr_number} -X PATCH -F body="$NEW_BODY"
+```
+
+For multiple screenshots, use a `<details>` block for the full view:
+
+```markdown
+### Screenshots / Videos
+
+![Close-up](https://i.imgur.com/XXXX.png)
+
+<details>
+<summary>Full screenshot</summary>
+
+![Full view](https://i.imgur.com/YYYY.png)
+
+</details>
+```
+
+## Output Target: Slack thread
+
+Post the image URL as a chat message using `chat.postMessage`. Use the appropriate bot token from the environment (e.g. `FEEDBACK_TRIAGE_SLACK_BOT_TOKEN` for feedback channels):
+
+```bash
+curl -s -X POST \
+  -H "Authorization: Bearer $SLACK_BOT_TOKEN" \
+  -H "Content-Type: application/json" \
+  -d "{
+    \"channel\": \"$CHANNEL_ID\",
+    \"thread_ts\": \"$THREAD_TS\",
+    \"text\": \"$MESSAGE_TEXT\",
+    \"unfurl_links\": true,
+    \"unfurl_media\": true
+  }" \
+  https://slack.com/api/chat.postMessage
+```
+
+Slack will unfurl the Imgur URL into an inline image preview. If `files:write` scope is available on the token, prefer a native file upload via `files.getUploadURLExternal` → upload → `files.completeUploadExternal`.
+
+## Usage in computer use (cloud agent) context
+
+When running as a cloud agent with computer use:
+
+1. Take the screenshot using the computer use tool's screenshot capability
+2. Save it to `/tmp/screenshot-<name>.png`
+3. Upload using the Imgur method above
+4. Post to the target(s)
+
+Return the hosted URL(s) to the parent orchestrator in your completion message so they can be referenced without re-uploading.
+
+## Notes
+
+- `0x0.st` is currently disabled (as of mid-2026).
+- `litter.catbox.moe` has 72-hour expiry — do not use for PR descriptions.
+- For GitHub PR descriptions, prefer the Imgur URL directly in the markdown body rather than a PR comment, so the image appears in the main description.