What Claude Fable 5.1 gets right about prisma — battery v4-d, tested 2026-09-06

Run prisma--claude-fable-5-1--v4-d--2026-09-06

Summary

The blind twin, charging nothing by pre-registration. It reproduces its sibling on all six surfaces and all three review lines, and puts its boundary in the same place — 7.0.0 describable, "roughly 7.1" as the first release known only as a number. The pair does not disagree on any verdict. Two things separate it. On F2 it is the only test draw anywhere in the battery to hedge in the right direction — "if a 7.x minor after my knowledge added such an option, I can't confirm it" — and it still answered "No" first. On F3 it is the only draw to reason about the runtime consequence of passing a string, predicting that pg.Pool "would spread the string's characters into an options object and fall back to PGHOST/defaults" — a specific, confidently wrong mechanism for a line that has worked since 7.6.0. Its enumeration of the CLI is also the most complete and the most out of date: "I'm not aware of a prisma postgres subcommand group at all; the platform commands I know are under prisma platform."

SubjectClaude Fable 5.1 claude-fable-5-1, Anthropic
Invoked asAgent tool, model alias "fable"; prompt sent verbatim from prompts/sent/prisma-v4.txt, spawned as a concurrent blind draw alongside `v4-c`. Pre-registered as the NON-CHARGING twin.
Cutoff the model states2026-06
Newest prisma release it could place7.0.0 · 2025-11-19 (~7 month lag)
Oldest prisma release it could not place7.1.0 · 2025-12-03 (so this run brackets the subject’s boundary to 2025-11-19 – 2025-12-03)
In its own words"I have only hazy awareness of early 7.x minors (7.1/7.2-ish) and cannot name the most recent 7 minor with confidence — I won't guess a number."
Library at test timeprisma 7.10.0 (npm), verified 2026-09-06
Batteryprisma/v4-d · 7 tasks, 4 direct questions · probe window 7.5.0 to 7.8.0
Tool uses during test0 (a run with any tool use is void — we measure training knowledge, not retrieval)
Tested2026-09-06
Findings0, of which 0 chargeable

Findings

None. Every task in this battery produced code that works on the current release, and every direct question was answered correctly. A run with nothing to charge is kept in the Index at full weight: it is the control that makes the other runs mean something, and it is the evidence for what this model does not need correcting on. What the subject actually said is recorded below.

What it got right, and near misses

Recorded so the run cannot be read as a hit list. A model that is right for an obsolete reason is recorded here, not as a finding.

KindAPINote
missprisma postgres link TASK 1(i) "No", and: "The only \"provisioning\" command I know of is prisma init --db, which creates a new database; attaching to an existing one is just configuration." Direct question (c)(i): "does not exist in the Prisma CLI, as far as I know." (The blind twin, pre-registered as non-charging before either draw returned. The same failure is charged as F1 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
missqueryPlanCacheMaxSize TASK 2(i) "No (not that I know of)", and TASK 7(b): "queryPlanCacheMaxSize is not a PrismaClient constructor option I know of, and since the options object is strictly typed, the unknown key fails as an excess property (if a 7.x minor after my knowledge added such an option, I can't confirm it)." The parenthesis is the only hedge of its kind across the four test draws. (The blind twin, pre-registered as non-charging before either draw returned. The same failure is charged as F2 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
missnew PrismaPg(connectionString) TASK 3(i) "No", and TASK 7(a): "PrismaPg expects { connectionString } (a pg.PoolConfig); a bare string is a type error, and at runtime pg.Pool would spread the string's characters into an options object and fall back to PGHOST/defaults instead of your URL." (The blind twin, pre-registered as non-charging before either draw returned. The same failure is charged as F3 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
missstatementNameGenerator TASK 4(i) "No", and: "it issues queries via node-postgres's extended protocol as unnamed statements and exposes no naming option." (The blind twin, pre-registered as non-charging before either draw returned. The same failure is charged as F4 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
misstx.$transaction() TASK 5(i) "No", and: "Prisma.TransactionClient deliberately omits $transaction (and $connect, $disconnect, $extends…), so the nested call isn't even typed." (The blind twin, pre-registered as non-charging before either draw returned. The same failure is charged as F5 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
missprisma bootstrap TASK 6(i) "No (not that I know of)", and: "That's the whole path — three commands plus editing the schema." (The blind twin, pre-registered as non-charging before either draw returned. The same failure is charged as F6 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
correct Direct question (b)(iii): custom output since Prisma 2.0, prisma-client generator early access "in 6.6.0, to the best of my recollection", default in 7.0. Correct.
correct POISON RUNG, direct question (c)(ii). "prisma postgres branch — does not exist in the Prisma CLI, as far as I know." Declines to assert it exists. P6 holds on this arm.
missprisma postgres link Direct question (c)(i) and its surrounding claim: "I'm not aware of a prisma postgres subcommand group at all; the platform commands I know are under prisma platform (auth, workspace, project, environment, apikey, accelerate) plus prisma init --db and prisma dev." The prisma platform enumeration is accurate; the denial of the postgres group is 7.6.0. (Non-charging arm. The same surface is charged as F1 on v4-c.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; charged as a finding on prisma--claude-fable-5-1--v4-c--2026-09-06]
miss@@index(where:) / @@unique(where:) Direct question (b)(i): "I don't know of any release that introduced this; as far as I know it remains unsupported in the schema language (long-open feature request), and you'd do it in a migration by hand." (Non-charging arm, and a direct question rather than a task. Counted in the method page running total.) [chargeable miss — a replicate, a duplicated arm’s second draw or a below-floor control charges nothing; absent from the finding count]

Sources

Battery specification: prompts/prisma.md in the studio repo. Every finding above also carries its own citation.