The 11-layer harness vs. a bare model loop

Compare: lookup-http-418

Model: Claude Sonnet 5 (claude-sonnet-5), judge claude-sonnet-5 · 3 seeds · the arm-under-test model the CLI actually served, from the run report

Prompt

What does HTTP status code 418 mean?
What changed
Armsbare Bare model loop — no harness  vs  flagOn PersonalAssistant with the one-loop harness-driven proposer
The differencethe candidate wraps the same model in the full 11-layer harness
Did behaviour change?
Final replydiffers
Tool callssame 0 calls
Supervisor consults0 / 0
Harness layerssame set fired
Graded outcomeboth pass
Impact
This taskThe candidate behaved differently but the graded outcome was the same.
Shown seedcost +50% · latency +8% · tokens -62% (candidate vs control, seed 1)

Side by side — control (left) vs candidate (right), seed 1

bare — control
flagOn — candidate
Final reply
HTTP status code 418 means **"I'm a teapot."** It originates from the **Hyper Text Coffee Pot Control Protocol (HTCPCP)**, defined in RFC 2324, which was published on April 1, 1998 as an April Fools' Day joke by the IETF. According to the spec, any attempt to brew coffee with a teapot should result in the error "418 I'm a teapot," and the response body "MAY be short and stout." Key points: - **Not an official HTTP status code** – it's not part of the real HTTP standard (RFC 7231, etc.). - It
HTTP 418 means **"I'm a teapot."** It originated from RFC 2324, the *Hyper Text Coffee Pot Control Protocol* (HTCPCP), an April Fools' joke published in 1998. The spec says any attempt to brew coffee with a teapot should return 418, since a teapot cannot brew coffee. It was never intended as a real status code, but it became a popular Easter egg — many web frameworks and servers implement it as a joke, and it's sometimes used informally to reject unwanted requests. There was a brief effort to
Tool calls

no tool calls

no tool calls

Grader checks
CheckVerdict
contains "teapot"pass
not contains "418 is not a real"pass
not contains "no such status code"pass
not contains "418 means Payload Too Large"pass
not contains "418 is Unauthorized"pass

success yes  ·  hallucination no  ·  unauthorized effect no  ·  recovered n/a

CheckVerdict
contains "teapot"pass
not contains "418 is not a real"pass
not contains "no such status code"pass
not contains "418 means Payload Too Large"pass
not contains "418 is Unauthorized"pass

success yes  ·  hallucination no  ·  unauthorized effect no  ·  recovered n/a

Metrics
latency8270 ms
cost$0.0063
tokens961
supervisor consults
latency8960 ms
cost$0.0095
tokens367
supervisor consults0

Other seeds — seed 2: pass · $0.0055 · 7.3 s   seed 3: fail · — · 1.6 s

Other seeds — seed 2: pass · $0.0097 · 9.3 s   seed 3: pass · $0.0104 · 10.8 s

Read the full turn

Conversation — bare (control) · seed 1
user
What does HTTP status code 418 mean?
model
HTTP status code 418 means **"I'm a teapot."**

It originates from the **Hyper Text Coffee Pot Control Protocol (HTCPCP)**, defined in RFC 2324, which was published on April 1, 1998 as an April Fools' Day joke by the IETF. According to the spec, any attempt to brew coffee with a teapot should result in the error "418 I'm a teapot," and the response body "MAY be short and stout."

Key points:

- **Not an official HTTP status code** – it's not part of the real HTTP standard (RFC 7231, etc.).
- It has become a widely recognized Easter egg. Many web frameworks and servers implement it as a joke, and some sites return it for playful purposes (for example, Google's `google.com/teapot` endpoint).
- In 2017, there was a proposal to remove teapot-related references from some software, which sparked a "Save 418" movement among developers who wanted to preserve the joke.
- RFC 7168 later extended HTCPCP to handle teapots (HTCPCP-TEA), formally reusing the 418 code for teapots refusing to brew coffee.

So if you ever see a 418, a server is humorously telling you it can't do what you asked because it is, in fact, a teapot.
final reply
HTTP status code 418 means **"I'm a teapot."**

It originates from the **Hyper Text Coffee Pot Control Protocol (HTCPCP)**, defined in RFC 2324, which was published on April 1, 1998 as an April Fools' Day joke by the IETF. According to the spec, any attempt to brew coffee with a teapot should result in the error "418 I'm a teapot," and the response body "MAY be short and stout."

Key points:

- **Not an official HTTP status code** – it's not part of the real HTTP standard (RFC 7231, etc.).
- It 
Conversation — flagOn (candidate) · seed 1
user
What does HTTP status code 418 mean?
risk LOW
proposer posthoctrivialmode FAST
model
HTTP 418 means **"I'm a teapot."**

It originated from RFC 2324, the *Hyper Text Coffee Pot Control Protocol* (HTCPCP), an April Fools' joke published in 1998. The spec says any attempt to brew coffee with a teapot should return 418, since a teapot cannot brew coffee.

It was never intended as a real status code, but it became a popular Easter egg — many web frameworks and servers implement it as a joke, and it's sometimes used informally to reject unwanted requests. There was a brief effort to remove it from software libraries around 2017, which sparked a "Save 418" movement, so it has largely stuck around.
final reply
HTTP 418 means **"I'm a teapot."**

It originated from RFC 2324, the *Hyper Text Coffee Pot Control Protocol* (HTCPCP), an April Fools' joke published in 1998. The spec says any attempt to brew coffee with a teapot should return 418, since a teapot cannot brew coffee.

It was never intended as a real status code, but it became a popular Easter egg — many web frameworks and servers implement it as a joke, and it's sometimes used informally to reject unwanted requests. There was a brief effort to 

Harness trace

Full harness trace — flagOn · seed 1

The harness runs on every turn. Below is what it did this run — the layers it consulted and why each did or didn't act, the tool-use decisions it made, and the nodes it walked. Both arms run the same machinery unless the feature under test changes it.

risk LOWproposer posthocmode FAST

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