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🔍 Read the full analysis: A Role-Based Guide To My September 2026 AI Stack on ThorstenMeyerAI.com

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TL;DR

A September 29 guide assigns Claude Opus 5.5 to building and newly released GPT-6.1 Sol to detailed review, while cheaper models handle routine tasks. The author’s comparisons use Artificial Analysis Intelligence Index v4.3.x and task-cost estimates; they are one person’s workflow, not proof of performance on every workload.

Thorsten Meyer published a role-based guide to his AI stack on September 29, assigning Claude Opus 5.5 to software building and newly released GPT-6.1 Sol to detailed review and analysis. The guide argues that with several models scoring within about 20 points on the cited benchmark but differing widely in estimated task cost, users should choose by workload and price rather than leaderboard rank alone.

Meyer says he uses Opus 5.5 at high effort for features, APIs, multi-file work and refactors, and xhigh for harder architectural work. In the Artificial Analysis Intelligence Index v4.3.x figures he cites, Opus scores 54 at high effort for an estimated $1.82 per task, and 56 at xhigh for $3.46. Its maximum setting scores 58, but raises the estimated task cost to $5.98.

GPT-6.1 Sol, released September 29, is his choice for examining files and reviewing changes. The cited index lists it at 48 points and $0.21 per task at medium effort, 50 points and $0.32 at high, and 51 points and $0.39 at xhigh. Meyer says the higher settings take 57 to 69 seconds to produce a first token, making them less suited to interactive use.

The guide assigns Sonnet 5.5 and Luna to scoped subtasks and routine checks, while Astra or Fable serve as alternatives when tests favor them or Sol and Opus disagree. Meyer says the index is a general capability measure rather than a verdict on a particular workload, and recommends shadow-testing before switching systems.

At a glance
reportWhen: Published September 29, 2026; GPT-6.1 S…
The developmentThorsten Meyer published a September 29, 2026 guide to assigning AI models by role, incorporating the same-day release of GPT-6.1 Sol.

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 Task Costs Shape the Stack

The guide’s main practical claim is that task cost and quality need to be weighed together. Meyer’s table places Opus 5.5 at the top score, while Sol and Luna have much lower estimated costs per task. For teams running repeated reviews, extraction or routing, the cost gap could affect how often they can use a model, but the figures are benchmark estimates and do not establish savings for every organization.

It also highlights effort settings as a major cost choice. In Meyer’s cited results, moving Opus from medium to max increases task cost from $1.34 to $5.98 while its score rises from 51 to 58. He argues that max effort is rarely worthwhile for his work. This makes the guide relevant to developers and teams deciding whether extra model effort delivers enough quality improvement to justify its price.

Meyer recommends a separate model family for review, using Sol to check Opus’s work. That can provide another perspective, but independent review is not guaranteed: the guide itself cautions that two models can share the same flawed requirements. It says passing tests alone should not be treated as approval to ship.

Benchmarks Behind the September Guide

The article is a dated account of one user’s workflow, published September 29, 2026. Its model scores and estimated task costs are attributed primarily to Artificial Analysis Intelligence Index v4.3.x. Meyer describes that index as a map of general capability and advises readers to test models on their own tasks before changing systems.

The cited comparison lists Opus 5.5 at 58 points and $5.98 per task at its top setting; Sonnet 5.5 at 56 and $7.60; Fable 5.1 at 53 and $7.63; GPT-6 Astra at 53 and $3.26; GPT-6.1 Sol at 51 and $0.39; and GPT-6 Luna at 37 and $0.07. These are index figures and estimated task costs, not a guarantee of comparable results in a reader’s software, documents or business process.

Meyer also compares token prices: Opus at $4 input and $20 output per million tokens, Sol at $2 and $10, and Luna at $0.10 and $0.50. He warns that token price alone does not determine the cost of completed work, since additional human review time can outweigh a model-price saving.

““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

Limits of the Model Comparisons

The guide does not establish whether its benchmark rankings transfer to other workloads. Meyer says readers should shadow-test models before switching. The source also says one index point is within the noise, and that Artificial Analysis had not published GPT-6.1 Sol’s low or max effort results at the time of writing.

The excerpt does not provide a full method for the estimated cost-per-task calculations or independent measurements of the author’s workflow. Its final example about human review cost is marked illustrative, not measured, and the source text cuts off before completing it. Actual end-to-end costs and quality remain workload-dependent; the guide supplies no results from a controlled comparison across organizations.

Test the Stack on Real Work

Meyer’s recommended next step for readers is to shadow-test candidate models on their own tasks before replacing an existing workflow. Teams can compare output quality, latency and total cost, including the time people spend checking results, against their own requirements.

The GPT-6.1 Sol comparison may change as additional effort-level results become available in the index. Until then, the guide’s role assignments remain the author’s September 29 snapshot, not a settled ranking for all uses.

Key Questions

What is the main development in the guide?

Thorsten Meyer published a role-based AI workflow on September 29, 2026, including GPT-6.1 Sol, released that day, as a model for detailed review and analysis.

Which models does Meyer use for building and review?

He assigns Opus 5.5 to primary building and GPT-6.1 Sol to file-level analysis and review, using different effort settings depending on task difficulty.

Are the cost figures guaranteed for other users?

No. They are estimated task costs in the cited Artificial Analysis index comparison. Meyer says the index does not decide which model fits a specific workload and recommends shadow-testing.

Why does Meyer avoid maximum effort for some tasks?

In the figures he cites, higher effort raises estimated cost substantially for a relatively small score increase in some cases. His example is Opus 5.5 at max, estimated at $5.98 per task versus $1.82 at high.

Source: ThorstenMeyerAI.com

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