Measured cost and latency
Measured from every Jev request logged between 2026-09-27T07:13:10.000Z and 2026-09-27T07:20:51.019Z (770 attempts: 770 answered, 0 without usage), Worker version 2f03062938a0. Generated 2026-09-27T07:20:51.356Z. These numbers replace the estimates in the architecture document §12.
Requests by kind
| kind | requests | answered | no usage | Σ input tokens | Σ output tokens | mean latency ms | p95 latency ms |
|---|---|---|---|---|---|---|---|
| eval | 172 | 172 | 0 | 2,358,483 | 456,557 | 360 | 472 |
| full | 598 | 598 | 0 | 4,668,010 | 718,195 | 341 | 450 |
| total | 770 | 770 | 0 | 7,026,493 | 1,174,752 |
Latency is the provider round trip of answered requests; p95 is linearly interpolated.
By kind and scenario
| kind | scenario | requests | answered | Σ input tokens | mean latency ms | p95 latency ms |
|---|---|---|---|---|---|---|
| eval | customer_success | 81 | 81 | 1,075,863 | 344 | 425 |
| eval | onboarding | 91 | 91 | 1,282,620 | 373 | 521 |
| full | customer_success | 306 | 306 | 2,207,139 | 330 | 441 |
| full | onboarding | 292 | 292 | 2,460,871 | 353 | 478 |
Replays per scenario
| scenario | replay sessions | decision points | Σ input tokens | tokens per decision point | cost per replayed call |
|---|---|---|---|---|---|
| customer_success | 4 | 306 | 2,207,139 | 7,213 | $0.0232 |
| onboarding | 4 | 292 | 2,460,871 | 8,428 | $0.0258 |
Cost per replayed call is Σ input tokens ÷ replay sessions × $0.042/M (output not priced); a session that stopped early counts as one call.
Credit balance against usage
credit delta: not measured (dashboard-only); effective $/Mtok assumed at list price $0.042/M input, output free
The AI Gateway "Credits Available" balance has no API. Reading it just before and just after a replay and re-running with --balance-before <usd> --balance-after <usd> reconciles the window.
AI Gateway analytics cross-check
aiGatewayRequestsAdaptiveGroups for gateway jev-copilot over the same window, independent of the request log above.
| model | requests | tokens in | tokens out | gateway cost | cost per Mtok in |
|---|---|---|---|---|---|
| typesafe/jev | 765 | 6,990,232 | 1,169,400 | $0.2936 | $0.0420 |
The two are counted independently: the gateway sees every caller routed through it (local scripts as well as the Worker) and records its own view of attempts that failed, so its figures differ from the request log by a few percent.
Characters per token
Σ request characters ÷ Σ input tokens over the 770 answered requests: 25,261,132 ÷ 7,026,493.
measured chars_per_token: 3.6
unknown_usage_requests: 0 (0 characters sent without a usage figure; not in the divisor).
Cold start
A session's first answered request against its own median, as the cold-start proxy.
| scenario | sessions | first request mean ms | session median mean ms | first − median ms |
|---|---|---|---|---|
| customer_success | 4 | 822 | 304 | 517 |
| onboarding | 4 | 940 | 313 | 627 |