The 11-layer harness vs. a bare model loop

Compare: lookup-speed-of-light

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 is the speed of light in a vacuum, in metres per second? Give the standard textbook value.
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 +195% · latency +118% · tokens -67% (candidate vs control, seed 1)

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

bare — control
flagOn — candidate
Final reply
The speed of light in a vacuum is 299,792,458 metres per second (exactly, by definition). This is often approximated as 3.00 × 10⁸ m/s in textbooks.
The speed of light in a vacuum is **299,792,458 metres per second** (exactly, by definition of the metre). The common textbook approximation is **3.00 × 10⁸ m/s**.
Tool calls

no tool calls

no tool calls

Grader checks
CheckVerdict
not contains "299,792,459"pass
not contains "299,000,000 m/s"pass
not contains "2,998,000 m/s"pass
not contains "3,000 m/s"pass
regex /299[,. ]?792[,. ]?458|3\s*(×|x|\*)\s*10\s*\^?\s*8|300[,. ]?000[,. ]?000/ipass

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

CheckVerdict
not contains "299,792,459"pass
not contains "299,000,000 m/s"pass
not contains "2,998,000 m/s"pass
not contains "3,000 m/s"pass
regex /299[,. ]?792[,. ]?458|3\s*(×|x|\*)\s*10\s*\^?\s*8|300[,. ]?000[,. ]?000/ipass

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

Metrics
latency2638 ms
cost$0.0027
tokens609
supervisor consults—
latency5740 ms
cost$0.0080
tokens199
supervisor consults0

Other seeds — seed 2: pass · $0.0027 · 2.5 s   seed 3: fail · — · 1.6 s

Other seeds — seed 2: pass · $0.0077 · 6.1 s   seed 3: pass · $0.0079 · 5.7 s

Read the full turn

Conversation — bare (control) · seed 1
user
What is the speed of light in a vacuum, in metres per second? Give the standard textbook value.
final reply
The speed of light in a vacuum is 299,792,458 metres per second (exactly, by definition). This is often approximated as 3.00 × 10⁸ m/s in textbooks.
Conversation — flagOn (candidate) · seed 1
user
What is the speed of light in a vacuum, in metres per second? Give the standard textbook value.
risk LOW
proposer posthoctrivialmode FAST
final reply
The speed of light in a vacuum is **299,792,458 metres per second** (exactly, by definition of the metre).

The common textbook approximation is **3.00 × 10⁸ m/s**.

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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