| name | nano-banana |
| description | Generate images from the terminal with Google's nano-banana (Gemini image model) via the Antigravity CLI (`agy`), billed to the signed-in Google account. Use whenever the user asks to create / draw / generate an image, picture, icon, logo, illustration, poster, infographic, or diagram specifically with nano-banana / Gemini / Antigravity — or wants rich, text-heavy infographics. For the OpenAI gpt-image-2 path use the separate `gpt-image` skill instead. |
| allowed-tools | Bash, Read |
nano-banana — image generation via Antigravity (agy)
Wraps the agy (Google Antigravity) agent so Claude Code can generate images with
nano-banana. Unlike a plain CLI, image generation here is an agent tool
(generate_image) invoked through natural language — the wrapper builds a strict
instruction, runs agy -p, then verifies the output file actually landed (with
recovery from agy's brain/ working dir). Auth is the Google account signed into agy.
All commands go through the helper:
~/.claude/skills/nano-banana/scripts/nano-banana.sh <check|generate|batch> [args]
Workflow
- Preflight once per session:
nano-banana.sh check. If it reports no creds /
auth, the user must run agy once interactively to log in (browser OAuth) — you
cannot do this for them. Token expiry surfaces at generate time as an auth error.
- Generate with an explicit
--output PNG path. The helper prints
IMAGE\t<path>\t<WxH> on success.
- Always
Read the produced PNG to view it and verify, then report the path.
- Iterate by re-running with a refined prompt.
Commands
Generate (text → PNG):
~/.claude/skills/nano-banana/scripts/nano-banana.sh generate \
--prompt "PROMPT TEXT" --output ./out.png
Batch (many prompts → many images; one per prompt, continue-on-error, manifest):
~/.claude/skills/nano-banana/scripts/nano-banana.sh batch \
--prompts-file ./prompts.txt --outdir ./renders
~/.claude/skills/nano-banana/scripts/nano-banana.sh batch --prompt "a" --prompt "b" --outdir ./out
printf 'one\ntwo\n' | ~/.claude/skills/nano-banana/scripts/nano-banana.sh batch --prompts-file -
Name an output by prefixing a line with stem<TAB>prompt (else 001.png, …).
Default --outdir is ./nb-batch-<timestamp>/; read <outdir>/manifest.tsv for the
stem→status→path→prompt map. Per-image failures are recorded and skipped, but an
auth failure aborts the whole batch (no point retrying every prompt against dead
auth) — re-login with agy and re-run.
How it works / behaviors
- Underlying tool is
generate_image (nano-banana is the model). There is no
agy image subcommand — the agent calls the tool from the prompt.
- The agent generates a JPEG into
~/.gemini/antigravity-cli/brain/<conv-id>/, then
converts to PNG at your --output. The wrapper forces an absolute path and, if the
agent doesn't save there, recovers the newest brain image and converts it via sips.
- Output paths are absolutized (agy resets cwd). Parent dirs are created.
- One retry on a no-file result; auth/eligibility errors fail fast with guidance.
- Non-destructive: success requires the output file to actually change this run
(checked via its inode:mtime:size), so a pre-existing/stale file is never reported as a
fresh result and is not deleted if generation fails.
⚠️ Safety
This path drives an autonomous agent (agy -p … --dangerously-skip-permissions):
tool calls and file writes are auto-approved. A prompt is therefore not just image text —
a malicious or careless prompt could instruct the agent to run other tools or touch other
files. Only pass trusted prompt text (and trusted --prompts-file contents). For the
non-agent, capability-scoped path, prefer the gpt-image skill.
Strengths & limitations (vs gpt-image-2)
- Strengths: excellent in-image text rendering; tends to produce rich, fully
fleshed-out infographics (adds detail, gradients, sub-labels). Great for posters and
content-heavy diagrams; strong at consistent image editing (via prompt + a file path).
- Limitations:
- No precise size control through the agent — it returns its own dimensions
(often ~16:9). If you need an exact size, post-process with
sips -z H W.
- Slower than gpt-image-2 (it's an agent turn: tool call + format convert).
- Tends to elaborate — if you want strictly minimal output, say "minimal, no
extra text, exactly three boxes" etc.
- Needs a live
agy login; tokens expire and require interactive re-auth.
Troubleshooting
agy ... not found → install Antigravity (https://antigravity.google) or ensure
~/.local/bin is on PATH.- auth /
IneligibleTier / "Authentication required" → run agy once interactively to
log in; the standalone gemini CLI is not usable on free-tier accounts.
- No file produced → check stderr for the agy transcript; re-run (one retry is automatic).
