# Liquid d1

d1 is Liquid's decision model. Its server speaks System One, so ThinkThen asks it with no change but the backend name.

| Backend name | `liquid` |
| --- | --- |
| Address | `https://api.liquid.ai/decisions/v1` |
| Key variables | `LIQUIDAI_API_KEY`, then `LIQUID_API_KEY` |
| Default model | `d1:free` |

Liquid launched d1 on 2026-09-29. Liquid's model list gives a release date of 2026-09-22. On 2026-09-30 that list held one model, `d1:free`, and Liquid published no price for it. Its replies count input tokens only, and output tokens are always zero.

## Get a key

1. Sign in at [console.liquid.ai](https://console.liquid.ai).
2. Open Dashboard, then API Keys, and create a key. It starts with `liquid_`.
3. Put it in `LIQUIDAI_API_KEY`. ThinkThen also reads `LIQUID_API_KEY` when the first is unset.

These steps were checked on 2026-09-29.

*status names the address, the model, and the variable the key comes from. It sends nothing.*

```
thinkthen status --backend liquid |
grep -E '^(backend|url|model|key_variable) '
```

*Output*

```
backend liquid
url https://api.liquid.ai/decisions/v1/systemone
model d1:free
key_variable LIQUIDAI_API_KEY
```

*exit 0*

## Check it

A first check can outlast the default timeout. Pass `--timeout 90` on a first run. On 2026-09-30, a first check timed out at 30 seconds and passed with `--timeout 90`. The [check page](/reference/check/#limits) says how long a check can take.

*The check would post to Liquid's address with d1:free. The plan sends nothing.*

```
thinkthen check \
  --backend liquid \
  --timeout 90 \
  --plan |
head -n 4
```

*Output*

```
url https://api.liquid.ai/decisions/v1/systemone
provider systemone
model asked unspecified
model sent d1:free
```

*exit 0*

On 2026-09-30, thinkthen check on build 74b82a8e1 asked d1:free and exited 0, with 0 critical and 0 warning findings.[The record](https://github.com/botassembly/thinkthen/blob/main/sdlc/issues/closed/2026-09-29-systemone-adapter-sends-null-criteria-liquid-d1-refuses.md) holds the run.

## A first answer

The send-back line is ambiguous. A customer who sends an item back may want an exchange or money back.

*d1 answers no and exits 1. Jev answers yes to the same line.*

```
question="Does the customer ask for a refund?"

printf '%s\n' "I want to send this back." |
thinkthen decide "$question" --backend liquid
```

*Output*

```
false
```

*exit 1: no*

*One request carries all three lines. d1 says yes to the broken order and no to the send-back line.*

```
question="Does the customer ask for a refund?"

cat <<'EOF' |
Please refund my order. It arrived broken.
Thanks for the quick help yesterday!
I want to send this back.
EOF
thinkthen decide "$question" \
  --lines \
  --backend liquid
```

*Output*

```
{"input":"Please refund my order. It arrived broken.","value":true}
{"input":"Thanks for the quick help yesterday!","value":false}
{"input":"I want to send this back.","value":false}
```

*exit 0: the run finished*

## Without the backend name

The address and a key work without the name too. Set `THINKTHEN_BASE_URL=https://api.liquid.ai/decisions/v1`, put the key in `THINKTHEN_API_KEY`, and pass `--model d1:free`.

## From your language

Each page shows how its language names a backend.

- [Bash](/install/shell/#backends)
- [Python](/install/python/#backends)
- [TypeScript](/install/typescript/#backends)
- [Ruby](/install/ruby/#backends)
- [R](/install/r/#backends)
- [Rust](/install/rust/#backends)
- [C](/install/c/#backends)
- [C++](/install/cpp/#backends)
- [Objective-C](/install/objective-c/#backends)
- [COBOL](/install/cobol/#backends)
- [Ada](/install/ada/#backends)
- [Java](/install/java/#backends)
- [Kotlin](/install/kotlin/#backends)
- [Scala](/install/scala/#backends)
- [C#](/install/csharp/#backends)
- [Go](/install/go/#backends)
- [Swift](/install/swift/#backends)
- [Zig](/install/zig/#backends)
- [PHP](/install/php/#backends)
- [Dart](/install/dart/#backends)

[All backends](/install/backends/) · [Configuration](/install/configuration/)

On GitHub: [github.com/botassembly/thinkthen](https://github.com/botassembly/thinkthen)