🖼️ Demo 4 — Image batch resize (scheduled job)

Goal: every hour, take any image dropped into c:\temp\images-in\ and produce a 256×256 WebP thumbnail in c:\temp\images-out\. Skip files that already have a matching thumbnail.

Time to complete: ~10 minutes. Tools used: file_system, image_edit. Surface: Jobs page (UI-first), with REST alternative.

🎯 Skip the typing — use the built-in template. Open Jobs → Job Templates and pick Image batch resize (hourly) (id image-batch-resize).

💡 Why this scenario? Same shape as Demo 1 (folder-watcher), but it shows the image_edit tool and demonstrates that a job can write its outputs to the central Storage:RootPath instead of next to the source.

Step 0 — Prepare folders + a sample image#

New-Item -ItemType Directory -Path c:\temp\images-in  -Force | Out-Null
New-Item -ItemType Directory -Path c:\temp\images-out -Force | Out-Null
 
# Copy any local PNG/JPG into the input folder, e.g.:
Copy-Item "C:\Windows\Web\Wallpaper\Windows\img0.jpg" c:\temp\images-in\

Drop one or two more images of your choice into c:\temp\images-in\ if you have them handy.

Step 1 — Create the job#

Open the Web UI → Jobs → + New Job and fill:

Field	Value
Name	`Thumbnail builder`
Trigger	`Cron`
Schedule	`0 * * * ` (top of every hour — use `/5 * * ` to test faster)
Tools allowed	`file_system`, `image_edit`
Timeout	`300` seconds
Prompt	(see below)

You are a thumbnail batch worker.
 
1. Use file_system action="list" with path="c:\temp\images-in" to enumerate every file.
2. For each file with an extension of .jpg, .jpeg, .png, or .webp:
   a. Compute the output path:
      "c:\temp\images-out\" + <filename without extension> + "-256.webp"
   b. Use file_system action="exists" to check whether that output already exists.
      If it does, skip the file (do NOT regenerate).
   c. Otherwise call image_edit with:
        action  = "resize"
        input   = the full input path
        format  = "webp"
        width   = 256
        height  = 256
      The tool will create the file under <Storage>/binary/image-edit/<timestamp>-resize.webp.
   d. Read the absolute path from the tool result (the line starting with "Saved to:")
      and use file_system action="read" + action="write" — or, if available, a move —
      to place it at the output path computed in step (a).
3. Return a summary: files scanned, thumbnails created (with paths), files skipped.

Click Save, then Run now to fire it once without waiting.

Step 2 — Verify#

Get-ChildItem c:\temp\images-out

You should see one <name>-256.webp per input image. Drop another image into c:\temp\images-in\ and either click Run now or wait for the next cron tick — only the new file gets processed.

ℹ️ Where do the originals from image_edit live? The image_edit tool always writes a copy to <Storage:RootPath>\binary\image-edit\ (default c:\openclawnet\storage\binary\image-edit\) using a timestamped name. The job above reads that copy and places it at the friendly output path. You can prune the staging folder periodically with another small job if you wish.

REST alternative#

$body = @'
{
  "name": "Thumbnail builder",
  "trigger": { "type": "cron", "expression": "0 * * * *", "timezone": "UTC" },
  "toolsAllowed": ["file_system", "image_edit"],
  "timeoutSeconds": 300,
  "prompt": "You are a thumbnail batch worker. ... (full text from Step 1)"
}
'@
Invoke-RestMethod -Method Post -Uri http://localhost:5010/api/jobs `
  -ContentType 'application/json' -Body $body

Variations#

Add format=jpeg to also produce a JPEG variant for legacy clients.
Use action=crop with a fixed aspect ratio for square avatars.
Combine with Demo 1 so the job also writes a tiny <name>.txt caption for each new image (run the agent through markdown_convert-of-EXIF + summarize).

Where to go next#

docs/manuals/20-tools.md#image_edit — full image_edit reference (resize/convert/crop, supported formats, x/y crop origin).
docs/manuals/30-jobs.md — retry policies and timezones for production schedules.