image-generation

Image Generation

Generate images via Letta's hosted endpoint POST /v1/images/generations. The API usually returns base64 image bytes, but some providers return signed image URLs; save either form to a local image file before replying.

Example

Generate the image, save it locally, then show it inline:

base_url="${LETTA_BASE_URL%/}"

curl -sS -X POST "$base_url/v1/images/generations" \
  -H "Authorization: Bearer $LETTA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"provider":"gemini","prompt":"a friendly robot mascot waving, flat vector logo, mint green background","n":1}' \
  > image-response.json

python3 - <<'PY'
import base64, json, urllib.request

with open("image-response.json") as f:
    response = json.load(f)

image = response["images"][0]
if image.get("b64_json"):
    data = base64.b64decode(image["b64_json"])
else:
    data = urllib.request.urlopen(image["url"]).read()

with open("robot-mascot.png", "wb") as f:
    f.write(data)

print("saved robot-mascot.png")
PY

In Bash tools launched by Letta Code, use the runtime-provided LETTA_BASE_URL and LETTA_API_KEY together for Letta API calls. Build URLs relative to ${LETTA_BASE_URL%/} and send Authorization: Bearer $LETTA_API_KEY. Do not hardcode https://api.letta.com: Desktop and remote runtimes may provide a proxy base URL, and the credential may only be valid through that URL. If either variable is missing, the user needs to authenticate with Letta Cloud (or provide a Letta API key); do not ask for an OpenAI/Gemini provider key. This endpoint also does not use /connect BYOK providers — the only provider values supported here are flux, gemini, and openai.

Then show the image to the user by embedding the saved file in your reply:

Here's the mascot:

![a friendly robot mascot waving, flat vector logo](./robot-mascot.png)

The Letta Code UI renders local file paths in markdown image tags, so the image appears inline. Always display generated images this way — don't just report the path, and never paste the raw base64 / a data: URI. The markdown path must match where you saved the file. For n > 1, save each image to its own file and embed each on its own line. Keep credit amounts and billing metadata out of user-facing replies and captions unless the user asks about cost. When asked, read billing.credits_charged from the saved response.