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🔍 Read the full analysis: Three Roles, One Workflow: My September 2026 AI Stack on ThorstenMeyerAI.com

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TL;DR

Thorsten Meyer’s September 29 report describes a workflow that uses Claude Opus 5.5 for building and GPT-6.1 Sol for detailed review, with other models assigned narrower jobs. The reported benchmark scores are relatively close while task costs vary widely, but the figures are benchmark-specific and do not establish which model is best for other workloads.

Thorsten Meyer’s September 29 report sets out an AI workflow that assigns Claude Opus 5.5 to building and GPT-6.1 Sol to detailed review, while reserving other models for narrower tasks. The approach reflects a cost comparison in which the models’ Artificial Analysis Intelligence Index scores are relatively close but their reported cost per task ranges from $0.07 to $7.63.

Meyer says he uses Opus 5.5 at high effort for features, APIs and multi-file work, where the source lists a score of 54 and a cost of $1.82 per task. He raises it to xhigh effort for architecture, migrations and trust boundaries; that setting scores 56 and costs $3.46 per task in the cited index. He says max effort is rarely worth the added cost for his work.

For specific-file analysis and independent review, Meyer assigns GPT-6.1 Sol at high or xhigh effort. The index figures in his report put those settings at $0.32 and $0.39 per task, with scores of 50 and 51. He says Sol is very concise on the benchmark, but high and xhigh take 57 to 69 seconds to produce a first token, making those settings less suited to interactive use.

The report assigns Sonnet 5.5 to scoped subtasks and documents, and Luna to classification, extraction and routing. Meyer lists Astra and Fable as second opinions when Sol and Opus disagree. He also describes Jev as a decision model for high-volume yes-or-no and routing judgments, but the supplied material gives no benchmark figures for Jev.

At a glance
reportWhen: Published September 29, 2026; GPT-6.1 S…
The developmentThorsten Meyer published a September 29 account of how he assigns AI models to building, review and routing tasks using benchmark scores and estimated task costs.

Opus builds. Sol reviews. Jev decides.

The September 2026 AI stack in one page: six frontier models on one price curve, and a decision model for the high-volume judgements that do not need a sentence.
Scores: Artificial Analysis Intelligence Index v4.3.x. Data as of 29 September 2026.
BuildsClaude Opus 5.5 at high or xhigh effort
Digs and reviewsGPT-6.1 Sol at high or xhigh effort
DecidesJev on high-volume yes/no and routing calls

One price tape, six models

Put every model on the same cost-per-task ruler and capability looks compressed. The bill does not.
Price tape: cost per task of six models on a log scale, from GPT-6 Luna at $0.07 to Fable 5.1 at $7.63$0.05$0.10$0.50$1$5$10cost per task, log scale: each tick is a different order of magnitudeGPT-6 Lunaindex 37 · $0.07GPT-6.1 Solindex 51 · $0.39 (xhigh)GPT-6 Astraindex 53 · $3.26Opus 5.5index 58 · $5.98Sonnet 5.5 · index 56 · $7.60Fable 5.1 · index 53 · $7.63about 100× from the cheapest to the priciest, but only 21 index points between them

Score against cost, at every effort setting

Each dot is an effort level. Opus 5.5 at high already matches Astra and Fable at max on this index, for less money.
Intelligence Index score against cost per task for each effort setting of six models$0.01$0.10$1$102030405060cost per Intelligence Index task, log scaleindexOpus high / xhigh: my defaultOpus 5.5Sonnet 5.5Fable 5.1GPT-6 AstraGPT-6.1 Sol (new)GPT-6 Sol (Sep 22), dashedGPT-6 Lunaup and to the left is better
Astra and Fable are shown at their top published setting. Luna starts at $0.0045 per task. GPT-6.1 Sol has no low or max setting published yet.

The effort dial moves the bill more than the model

Going from medium to max on Opus costs 4.46× more for 7 points. That is why I run high or xhigh.

Claude Opus 5.5

$0.55
42
$1.34
51
$1.82
54
$3.46
56
$5.98
58
low
medium
high
xhigh
max
Solid bars are where I run it. Max adds 2 points over xhigh for 73% more cost.

Claude Sonnet 5.5

$0.41
36
$0.59
41
$1.08
47
$2.74
52
$7.60
56
low
medium
high
xhigh
max
Best value is high. At max it writes about 193k output tokens per task, the most measured.

GPT-6.1 Sol: near-Astra scores at a fraction of the price

Launched 29 September at $2 in and $10 out per 1M tokens. It sits 1 to 2 points under Astra and Fable, and Opus xhigh still leads it by 5.

Three published settings

SettingIndexCost per taskOutput tokensFirst token
medium48$0.2115M5.3 s
high50$0.3225M57 s
xhigh51$0.3936M69 s
Median for comparable models is 82M output tokens. High and xhigh are not interactive: plan for a wait before the first token.

Same score band, very different bill

GPT-6.1 Sol xhigh
$0.39index 51
Opus 5.5 high
$1.82index 54
GPT-6 Astra max
$3.26index 53
Opus 5.5 xhigh
$3.46index 56
Fable 5.1 max
$7.63index 53
Cost per Intelligence Index task. A one-point gap is inside the noise.

My stack: who builds, who reviews

Opus does the work. A second model family reviews it, because a different reviewer catches what the author cannot see.
Stack diagram: Opus 5.5 builds at high effort, escalates to xhigh, and sends every change to GPT-6.1 Sol for review; Astra or Fable give a second opinionOpus 5.5 · xhighhard problems: architecture,migrations, trust boundariesOpus 5.5 · highMAIN BUILDERfeatures, APIs, multi-filework, refactorsescalate when it gets hardGPT-6.1 Solhigh or xhighdigs into details andreviews every change$0.32–0.39 per taskdifffindingsAstra or Fablesecond opinion, 8 to 20×the cost per taskif they disagreeSonnet 5.5 · Lunaside work: scopedsubtasks, bulk checksand routingFailed review? Hand Opus the failing case and the evidence.Never just “try harder”: effort cannot supply a missing requirement.
Effort is not capability. Turning the dial up does not make a model smarter.
Effort cannot fill gaps. A missing requirement stays missing at any setting.
Different model, same spec. That is not independent review if both read the same flawed brief.
Green tests are not approval. Passing tests only prove what the tests cover.

Cheaper tokens are not cheaper work

Illustrative, not measured: $1 of model time plus 4 minutes of review at $45 an hour. Halving the model price saves 12.5% of the total. One extra minute of review erases it.
$4.00
review $3.00
model $1.00
Baseline
$3.50
review $3.00
model $0.50
Model price cut 50%
$4.25
review $3.75
model $0.50
Cheaper model plus 1 extra minute of review
Track cost per accepted result: model, tools, review and rework, divided by the results someone actually uses.

Read the numbers with four warnings

The index movesFable scored 66 on an earlier version and 53 on v4.3. Compare within one version only.
Fallback is includedFlagged cyber and biology tasks route to older Anthropic models, now on Sonnet 5.5 too.
Max is not productionReal deployments run medium or high, where gaps narrow and costs fall.
Your work decidesShadow-test on your own tasks. Budget cost per task, not per token.

Part 2: Jev, the model that decides instead of writing

Jev cannot write, summarise or extract. It answers narrow typed questions with a probability and an honest confidence, in under a second, for about $0.04 per million input tokens.

One call in, typed answers out

Your code, not Jev, decides what to do with each answer, usually by confidence band.
Jev flow: state and typed questions go into one Jev call; typed answers with confidence come out; code acts alone, escalates the gray zone, or logsStatea ticket, a story,a site profile,a log line …+ typed questions,many per callJevone call0.3 to 0.9 s$0.042 / M tokens inAnswersnoul: 0.03choice: billing p 0.91, conf 0.86score: 2.7 of 3 conf 0.64code branches on thisAct aloneconf ≥ 0.8Escalategray zone toLLM or humanLogmeasure first

Three question types

noul
A yes/no question. Returns the probability of yes, 0 to 1.
gates, flags, filters
choice
Pick one option. Returns the choice, a probability per option, and a confidence.
routing, classification, taxonomy
score
Rate on your ordered levels. Returns a position (it can fall between levels) plus a confidence.
quality, fit, severity, priority

Confidence is the superpower

In my own measurement on a 31-topic classification, Jev agreed with a frontier LLM almost every time it was sure, and rarely when it was not. So: decide the clear cases, route the gray zone.
confidence 0.8 or higher
97–99%
all answers
89%
confidence below 0.5
42%
Agreement with a frontier LLM, my production data, September 2026, rounded.

Three uses running in my publishing operation

About 90,000 decisions so far. Checks I could only afford on a sample now cover everything.
$2.01
Language check
78,889 articles scanned overnight. 1,576 in the wrong language found, 1,553 fixed in place.
22%
Relevance gate
About 10,000 story-to-site pairings judged in 3 days. Only 22% were clearly on-topic.
89%
Classifier fallback
Agreement with the primary LLM across 31 topics, used when that LLM errors.

The fit test, then the shadow test

Use Jev only when all four hold. Then prove it on past decisions before it acts on anything.
High volumeThousands of small calls, not a handful of big ones.
Narrow questionNo multi-step reasoning needed.
Cheap errorsOr unsure cases go to something smarter.
Heuristic failsVisibly, and measured, not assumed.
  1. Replay 300 to 500 past decisions
  2. Compare overall and per confidence band
  3. Read 20 disagreements, decide who was right
  4. High band at 95% or better?
  5. Own flag, off by default
  6. Canary on 5 to 10 units
  7. Roll out in the confident band only

24 use cases, sorted by how well they fit

Start from the strong fits. The amber ones need a measurement before you trust them, and the red ones fail one of the four conditions.
in productionstrong fitmeasure firstpoor fit

Proven in production

  • 1Relevance gate
  • 2Language check
  • 3Classifier fallback

Publishing and content

  • 4Thin-source detector
  • 5Same-event dedupe
  • 6Product fits roundup
  • 7Disclosure present
  • 8Headline quality
  • 9Comment moderation

Commerce and support

  • 10Support-ticket routing
  • 11Return-reason coding
  • 12Review to feature complaints
  • 13Catalogue taxonomy
  • 14Order-fraud pre-triage

Software and AI systems

  • 15LLM guardrail
  • 16RAG passage filter
  • 17Citation check
  • 18Tool and intent routing
  • 19Log-line triage
  • 20PR risk triage

Business ops and home

  • 21Inbox triage
  • 22Expense categorisation
  • 23Lead qualification
  • 24Smart-home intent

Limits, cost and one hard rule

No writing, summarising or extractionPair it with an LLM for the write step.
No world knowledgePut a snippet in the state; a bare name means nothing.
Reads your wording literallyA rewording moved my results about 2 points. Freeze it, re-measure after changes.
Weaker on non-English, maths, datesKeep those checks on an LLM. Early access, hosted API only.
100,000 decisions ≈ $2.50
About 60M input tokens at $0.042 per million, output free, roughly 600 tokens per three-question call. Latency 0.3 to 0.9 seconds.
Never the sole decision-maker for consequences about people. Hiring, credit, medical and legal outcomes stay with a human. Jev can sort and flag. A person decides.
Sources. Model scores, cost per task and speeds: Artificial Analysis, Intelligence Index v4.3.x, including the GPT-6.1 Sol medium, high and xhigh pages, checked 29 September 2026. Astra and Fable scores from the Artificial Analysis v4.3 announcement. Jev figures are my own production measurements, September 2026, rounded. The review-bill example is illustrative. Read the full article on thorstenmeyerai.com.

Why Meyer Splits Building and Review

The workflow shows how a buyer might use benchmark and price data to decide which model handles each task, rather than selecting a single model for every job. In Meyer’s account, the relatively low reported cost of Sol makes a separate review pass practical for more work, while Opus remains his choice for building and difficult engineering decisions.

That division is a personal operating choice, not proof that the same allocation will improve results elsewhere. The source itself cautions that the index measures general capability rather than performance on an individual workload. A team would need to compare quality, latency and total review time on its own tasks before changing its model assignments.

The Benchmark Behind the Model Choices

The model scores and task costs cited in the report come from the Artificial Analysis Intelligence Index v4.3.x, unless otherwise stated. In the top-setting comparison, Opus 5.5 scores 58 at $5.98 per task, while Sonnet 5.5 scores 56 at $7.60. Fable 5.1 scores 53 at $7.63, Astra scores 53 at $3.26, GPT-6.1 Sol scores 51 at $0.39, and Luna scores 37 at $0.07.

Meyer says GPT-6.1 Sol was released September 29 at the same listed token prices as GPT-6 Sol: $2 per million input tokens and $10 per million output tokens. He reports that Sol’s medium setting scored 48 for $0.21 per task, matching the earlier model’s score at one-fifth of its reported $1.06 task cost. The source also gives token prices for the other models, but these rates and index task costs are separate measurements.

Effort settings change the comparison. For Opus 5.5, the cited score rises from 51 at medium to 58 at max, while reported task cost increases from $1.34 to $5.98. Meyer’s preferred high setting scores 54 for $1.82. He says Sonnet 5.5’s max setting costs $7.60 for a score of 56, compared with $2.74 and a score of 52 at xhigh.

““The practical reading: Sol is not the model I ask to build. It is the model I can afford to run on everything.””

— Thorsten Meyer, in the September 29 report

What the Benchmark Cannot Establish

The reported scores and costs do not establish how the models perform on Meyer’s full workload or on other users’ tasks. The source advises shadow-testing before switching, but provides no results from such a test. It also says one index point falls within measurement noise and that Artificial Analysis had not yet published Sol’s low- or max-effort results.

The report does not define the full methodology behind its task-cost estimates or provide a measured comparison of human review time and total project cost. It says a minute of human review could erase savings from cheaper model pricing, but labels its example illustrative, not measured. The supplied source text ends partway through that example, so it does not give a complete calculation.

How Teams Could Test the Split

Meyer recommends shadow-testing models on the intended workload before changing a production workflow. A meaningful comparison would need to track output quality, model cost, response time and the human effort required to catch or correct errors. His report does not specify a date for further benchmark updates or say whether he plans to publish results from a workload-specific test.

For now, the described stack is a snapshot dated September 29, 2026, based on the index data available to Meyer at publication. The roles he assigns may change as model settings, prices and benchmark measurements change; the source gives no confirmed schedule for a future revision.

Key Questions

What model does Meyer use for building?

He says he uses Claude Opus 5.5 at high effort for features, APIs, multi-file work and refactors, and xhigh for harder engineering problems.

Why does he use GPT-6.1 Sol for review?

Meyer says Sol can examine specific files and review changes at a reported $0.32 to $0.39 per task at high or xhigh effort. That is his workflow choice, not a guarantee of review quality on other projects.

Are the model scores proof of which model is best?

No. The scores are from the Artificial Analysis Intelligence Index v4.3.x, which Meyer describes as a general capability measure. The report recommends testing models against the workload where they would be used.

What remains unknown about GPT-6.1 Sol?

The source says the index had not yet published Sol’s low- or max-effort scores. It also does not provide results from a shadow test on Meyer’s own tasks.

Source: ThorstenMeyerAI.com

This content is for general information only and is not financial, tax or legal advice. Consult a qualified professional for decisions about your money.
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