Feature Video

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Feature Video Walkthrough

Record browser interactions demonstrating a feature, stitch screenshots into an MP4 video, upload natively to GitHub, and embed in the PR description as an inline video player.

Prerequisites

• Local development server running (e.g., bin/dev, npm run dev, rails server)
• agent-browser CLI installed (load the agent-browser skill for details)
• ffmpeg installed (for video conversion)
• gh CLI authenticated with push access to the repo
• Git repository on a feature branch (PR optional — skill can create a draft or record-only)
• One-time GitHub browser auth (see Step 6 auth check)

Main Tasks

1. Parse Arguments & Resolve PR

Arguments: $ARGUMENTS

Parse the input:

• First argument: PR number, “current” (defaults to current branch’s PR), or path to an existing .mp4 file (upload-only resume mode)
• Second argument: Base URL (defaults to http://localhost:3000)

Upload-only resume: If the first argument ends in .mp4 and the file exists, skip Steps 2-5 and proceed directly to Step 6 using that file. Resolve the PR number from the current branch (gh pr view --json number -q '.number').

If an explicit PR number was provided, verify it exists and use it directly:

gh pr view [number] --json number -q '.number'

If no explicit PR number was provided (or “current” was specified), check if a PR exists for the current branch:

gh pr view --json number -q '.number'

If no PR exists for the current branch, ask the user how to proceed. Use the platform’s blocking question tool (question in OpenCode, request_user_input in Codex, ask_user in Gemini):

No PR found for the current branch.

1. Create a draft PR now and continue (recommended)
2. Record video only -- save locally and upload later when a PR exists
3. Cancel

If option 1: create a draft PR with a placeholder title derived from the branch name, then continue with the new PR number:

gh pr create --draft --title "[branch-name-humanized]" --body "Draft PR for video walkthrough"

If option 2: set RECORD_ONLY=true. Proceed through Steps 2-5 (record and encode), skip Steps 6-7 (upload and PR update), and report the local video path and [RUN_ID] at the end.

Upload-only resume: To upload a previously recorded video, pass an existing video file path as the first argument (e.g., /feature-video .context/systematic/feature-video/1711234567/videos/feature-demo.mp4). When the first argument is a path to an .mp4 file, skip Steps 2-5 and proceed directly to Step 6 using that file for upload.

1b. Verify Required Tools

Before proceeding, check that required CLI tools are installed. Fail early with a clear message rather than failing mid-workflow after screenshots have been recorded:

command -v ffmpeg

command -v agent-browser

command -v gh

If any tool is missing, stop and report which tools need to be installed:

• ffmpeg: brew install ffmpeg (macOS) or equivalent
• agent-browser: load the agent-browser skill for installation instructions
• gh: brew install gh (macOS) or see https://cli.github.com

Do not proceed to Step 2 until all tools are available.

2. Gather Feature Context

If a PR is available, get PR details and changed files:

gh pr view [number] --json title,body,files,headRefName -q '.'

gh pr view [number] --json files -q '.files[].path'

If in record-only mode (no PR), detect the default branch and derive context from the branch diff. Run both commands in a single block so the variable persists:

DEFAULT_BRANCH=$(gh repo view --json defaultBranchRef -q '.defaultBranchRef.name') && git diff --name-only "$DEFAULT_BRANCH"...HEAD && git log --oneline "$DEFAULT_BRANCH"...HEAD

Map changed files to routes/pages that should be demonstrated. Examine the project’s routing configuration (e.g., routes.rb, next.config.js, app/ directory structure) to determine which URLs correspond to the changed files.

3. Plan the Video Flow

Before recording, create a shot list:

1. Opening shot: Homepage or starting point (2-3 seconds)
2. Navigation: How user gets to the feature
3. Feature demonstration: Core functionality (main focus)
4. Edge cases: Error states, validation, etc. (if applicable)
5. Success state: Completed action/result

Present the proposed flow to the user for confirmation before recording.

Use the platform’s blocking question tool when available (question in OpenCode, request_user_input in Codex, ask_user in Gemini). Otherwise, present numbered options and wait for the user’s reply before proceeding:

Proposed Video Flow for PR #[number]: [title]

1. Start at: /[starting-route]
2. Navigate to: /[feature-route]
3. Demonstrate:
   - [Action 1]
   - [Action 2]
   - [Action 3]
4. Show result: [success state]

Estimated duration: ~[X] seconds

1. Start recording
2. Modify the flow (describe changes)
3. Add specific interactions to demonstrate

4. Record the Walkthrough

Generate a unique run ID (e.g., timestamp) and create per-run output directories. This prevents stale screenshots from prior runs being spliced into the new video.

Important: Shell variables do not persist across separate code blocks. After generating the run ID, substitute the concrete value into all subsequent commands in this workflow. For example, if the timestamp is 1711234567, use that literal value in all paths below — do not rely on [RUN_ID] expanding in later blocks.

date +%s

Use the output as RUN_ID. Create the directories with the concrete value:

mkdir -p .context/systematic/feature-video/[RUN_ID]/screenshots
mkdir -p .context/systematic/feature-video/[RUN_ID]/videos

Execute the planned flow, capturing each step with agent-browser. Number screenshots sequentially for correct frame ordering:

agent-browser open "[base-url]/[start-route]"
agent-browser wait 2000
agent-browser screenshot .context/systematic/feature-video/[RUN_ID]/screenshots/01-start.png

agent-browser snapshot -i
agent-browser click @e1
agent-browser wait 1000
agent-browser screenshot .context/systematic/feature-video/[RUN_ID]/screenshots/02-navigate.png

agent-browser snapshot -i
agent-browser click @e2
agent-browser wait 1000
agent-browser screenshot .context/systematic/feature-video/[RUN_ID]/screenshots/03-feature.png

agent-browser wait 2000
agent-browser screenshot .context/systematic/feature-video/[RUN_ID]/screenshots/04-result.png

5. Create Video

Stitch screenshots into an MP4 using the same [RUN_ID] from Step 4:

ffmpeg -y -framerate 0.5 -pattern_type glob -i ".context/systematic/feature-video/[RUN_ID]/screenshots/*.png" \
  -c:v libx264 -pix_fmt yuv420p -vf "scale=1280:-2" \
  ".context/systematic/feature-video/[RUN_ID]/videos/feature-demo.mp4"

Notes:

• -framerate 0.5 = 2 seconds per frame. Adjust for faster/slower playback.
• -2 in scale ensures height is divisible by 2 (required for H.264).

6. Authenticate & Upload to GitHub

Upload produces a user-attachments/assets/ URL that GitHub renders as a native inline video player — the same result as pasting a video into the PR editor manually.

The approach: close any existing agent-browser session, start a Chrome-engine session with saved GitHub auth, navigate to the PR page, set the video file on the comment form’s hidden file input, wait for GitHub to process the upload, extract the resulting URL, then clear the textarea without submitting.

Check for existing session

First, check if a saved GitHub session already exists:

agent-browser close
agent-browser --engine chrome --session-name github open https://github.com/settings/profile
agent-browser get title

If the page title contains the user’s GitHub username or “Profile”, the session is still valid — skip to “Upload the video” below. If it redirects to the login page, the session has expired or was never created — proceed to “Auth setup”.

Auth setup (one-time)

Establish an authenticated GitHub session. This only needs to happen once — session cookies persist across runs via the --session-name flag.

Close the current session and open the GitHub login page in a headed Chrome window:

agent-browser close
agent-browser --engine chrome --headed --session-name github open https://github.com/login

The user must log in manually in the browser window (handles 2FA, SSO, OAuth — any login method). Use the platform’s blocking question tool (question in OpenCode, request_user_input in Codex, ask_user in Gemini). Otherwise, present the message and wait for the user’s reply before proceeding:

GitHub login required for video upload.

A Chrome window has opened to github.com/login. Please log in manually
(this handles 2FA/SSO/OAuth automatically). Reply when done.

After login, verify the session works:

agent-browser open https://github.com/settings/profile

If the profile page loads, auth is confirmed. The github session is now saved and reusable.

Upload the video

Navigate to the PR page and scroll to the comment form:

agent-browser open "https://github.com/[owner]/[repo]/pull/[number]"
agent-browser scroll down 5000

Save any existing textarea content before uploading (the comment box may contain an unsent draft):

agent-browser eval "document.getElementById('new_comment_field').value"

Store this value as SAVED_TEXTAREA. If non-empty, it will be restored after extracting the upload URL.

Upload the video via the hidden file input. Use the caller-provided .mp4 path if in upload-only resume mode, otherwise use the current run’s encoded video:

agent-browser upload '#fc-new_comment_field' [VIDEO_FILE_PATH]

Where [VIDEO_FILE_PATH] is either:

• The .mp4 path passed as the first argument (upload-only resume mode)
• .context/systematic/feature-video/[RUN_ID]/videos/feature-demo.mp4 (normal recording flow)

Wait for GitHub to process the upload (typically 3-5 seconds), then read the textarea value:

agent-browser wait 5000
agent-browser eval "document.getElementById('new_comment_field').value"

Validate the extracted URL. The value must contain user-attachments/assets/ to confirm a successful native upload. If the textarea is empty, contains only placeholder text, or the URL does not match, do not proceed to Step 7. Instead:

1. Check agent-browser get url — if it shows github.com/login, the session expired. Re-run auth setup.
2. If still on the PR page, wait an additional 5 seconds and re-read the textarea (GitHub processing can be slow).
3. If validation still fails after retry, report the failure and the local video path so the user can upload manually.

Restore the original textarea content (or clear if it was empty). A JSON-encoded string is also a valid JavaScript string literal, so assign it directly without JSON.parse:

agent-browser eval "const ta = document.getElementById('new_comment_field'); ta.value = [SAVED_TEXTAREA_AS_JS_STRING]; ta.dispatchEvent(new Event('input', { bubbles: true }))"

To prepare the value: take the SAVED_TEXTAREA string and produce a JS string literal from it — escape backslashes, double quotes, and newlines (e.g., "text with \"quotes\" and\nnewlines"). If SAVED_TEXTAREA was empty, use "". The result is embedded directly as the right-hand side of the assignment — no JSON.parse call needed.

7. Update PR Description

Get the current PR body:

gh pr view [number] --json body -q '.body'

Append a Demo section (or replace an existing one). The video URL renders as an inline player when placed on its own line:

## Demo

https://github.com/user-attachments/assets/[uuid]

*Automated video walkthrough*

Update the PR:

gh pr edit [number] --body "[updated body with demo section]"

8. Cleanup

Ask the user before removing temporary files. If confirmed, clean up only the current run’s scratch directory (other runs may still be in progress or awaiting upload).

If the video was successfully uploaded, remove the entire run directory:

rm -r .context/systematic/feature-video/[RUN_ID]

If in record-only mode or upload failed, remove only the screenshots but preserve the video so the user can upload later:

rm -r .context/systematic/feature-video/[RUN_ID]/screenshots

Present a completion summary:

Feature Video Complete

PR: #[number] - [title]
Video: [VIDEO_URL]

Shots captured:
1. [description]
2. [description]
3. [description]
4. [description]

PR description updated with demo section.

Usage Examples

# Record video for current branch's PR
/feature-video

# Record video for specific PR
/feature-video 847

# Record with custom base URL
/feature-video 847 http://localhost:5000

# Record for staging environment
/feature-video current https://staging.example.com

Tips

• Keep it short: 10-30 seconds is ideal for PR demos
• Focus on the change: don’t include unrelated UI
• Show before/after: if fixing a bug, show the broken state first (if possible)
• The --session-name github session expires when GitHub invalidates the cookies (typically weeks). If upload fails with a login redirect, re-run the auth setup.
• GitHub DOM selectors (#fc-new_comment_field, #new_comment_field) may change if GitHub updates its UI. If the upload silently fails, inspect the PR page for updated selectors.

Troubleshooting

Symptom	Cause	Fix
ffmpeg: command not found	ffmpeg not installed	Install via brew install ffmpeg (macOS) or equivalent
agent-browser: command not found	agent-browser not installed	Load the agent-browser skill for installation instructions
Textarea empty after upload wait	Session expired, or GitHub processing slow	Check session validity (Step 6 auth check). If valid, increase wait time and retry.
Textarea empty, URL is github.com/login	Session expired	Re-run auth setup (Step 6)
gh pr view fails	No PR for current branch	Step 1 handles this — choose to create a draft PR or record-only mode
Video file too large for upload	Exceeds GitHub’s 10MB (free) or 100MB (paid) limit	Re-encode: lower framerate (-framerate 0.33), reduce resolution (scale=960:-2), or increase CRF (-crf 28)
Upload URL does not contain user-attachments/assets/	Wrong upload method or GitHub change	Verify the file input selector is still correct by inspecting the PR page