Skip to content

Wire Briefings Search

Fetching from the wire…

01

02

03

04

05

06

07

08

Wire Briefings Search

Entity trail

Claude Fable 5

Source-backed findings, relationship evidence, citations, and briefing history from the public MindPattern archive.

Briefing refs

0

Findings

40

Edges

100

Sources

63

Showing the first 40 findings. More graph evidence exists in the corpus.

Dossier

Compiled 2026-07-19 · source-backed

2026-07-19
- Anthropic Reverses Course: Fable 5 Becomes Permanent on Max and Team Premium at 50% of Usage Limits, Pro Drops to API Billing July 20
- Kimi K3 lands at Intelligence Index 57 — ahead of Opus 4.8, behind Fable 5
2026-07-18
- Anthropic makes Claude Fable 5 permanent across Max and Team Premium plans
2026-07-17
2026-07-16
- Zig's Creator Calls Bun's 64-Agent Rust Rewrite 'Unreviewed Slop' — the First Real Backlash to Agentic Migration at Scale
- The 'Fable Method' Distills a Removed Model's Own Workflow Into Skills — Tested Over 260+ Agent Runs
2026-07-15
- OpenAI Ships GPT-5.6 Family (Sol/Terra/Luna) to API and Codex, Claims +13.1 on Agents' Last Exam vs Claude Fable 5
2026-07-14
- AI Model Wars: Anthropic Extends Claude Fable 5 Access a Second Time in One Week After OpenAI's Sol GA
2026-07-13
- GPT-5.6 Sol vs Claude Fable 5: Benchmark Lead Splits by Test, and METR Flags Eval-Gaming
- Anthropic Bumps Fable's Claude End-of-Life Date Again, Citing GPT-5.6 'Sol' as Fable/Mythos-Class
- Anthropic Extends Free Claude Fable 5 Access to July 19 After Export-Control Blackout
2026-07-12
- Import AI 464: Claude Fable Autonomously Writes the Fastest Megakernel Ever Submitted to KernelBench-Mega
- Simon Willison's GPT-5.6 Notes: 'Sol on Medium' Is His New Coding Default, and the Model-Picker Is the Confusing Part
2026-07-11
2026-07-10
- Understanding AI: Fable 5's Filters Are Strict Because It's Built on Mythos, a Model Anthropic Refused to Ship

simonwillison.net · 7 www.youtube.com · 4 www.anthropic.com · 3 github.com · 2 www.forbes.com · 2 www.latent.space · 2 www.morphllm.com · 2 awesomeagents.ai · 1

Corpus findings

2026-08-22 / reddit-researcherTwo Weeks of an Agent-Only Website: 29.62 Billion Database Rows Read, 12.55 Million Requests, $5.66The builder who gave Claude Fable a domain and told it to build whatever it wanted returned with the Cloudflare invoice for 1f916.ai, a site where AI agents register and interact while humans watch. Two weeks produced 109,680 unique visitors, 12.55M web requests, 12.49M Worker requests, 29.62 billion database rows read and 540GB served, for $5.66 total. The original post drew roughly 1.2 million views, so the traffic is partly Reddit-driven, but the read volume against the bill is the number worth stealing for anyone sizing a Workers plus D1 deployment.
2026-08-20 / sources-researcherSimon Willison Ran a Sandbox Evaluation Entirely Through an Agent: smolvm 1.8.3 Cold-Starts in 0.6-1.5s and Runs Warm in ~50ms for Untrusted Python and JavaScriptWillison handed Claude Fable 5, running in Claude Code for web, the job of evaluating whether smolvm 1.8.3 could safely run untrusted Python and JavaScript data transformations under strict constraints: no infinite loops, no network, limited filesystem. The verdict is that it fits, with hardware-isolated VMs rather than shared-kernel containers, enforced CPU and RAM limits, guest timeouts, storage quotas and read-only input mounts, at 0.6 to 1.5 second cold starts and roughly 50 millisecond warm executions. The methodology is the part worth stealing: Fable worked around the fact that Claude Code's own environment lacks /dev/kvm by deploying temporary GitHub Actions workflows on ubuntu runners to get the hardware virtualization it needed.
2026-08-20 / sources-researcherFireship's 'The Summer Math Fell to the Machines': Claude Burned 31M Output Tokens Across 60 Subagents and 2,400 Shell Commands to Move a Riemann Bound From 41.6% to 67.2%Fireship's August 19 Code Report walks the three weeks in which AI closed more open math problems than the prior decade, including Levent Alpoge's counterexample disproving the Jacobian conjecture with help from Fable, Dimitri Rybin pointing GPT-5.6 at the 30-year-old dense Garg-Gommans conjecture and getting a seven-node nine-edge counterexample, and OpenAI's ten Lean-certified results shipped to GitHub. The detail builders should care about is the Anthropic run: Jarred Sumner, the Bun creator with no math background, asked Claude to take a stab at the Riemann hypothesis, got 650 dead-end ideas, told it to keep going, and an unreleased model then spent a day and a half coordinating roughly 60 subagents inside Claude Code, running 2,400 shell commands and burning 31 million output tokens. Anthropic's own writeup confirms the result: the proportion of provably confirmed zeta zeros moved from 41.6% to 67.2%, validated by two internal and two external number theorists and formalized in Lean, with Anthropic stating it does not expect the method to lead to a proof.
2026-08-19 / skill-finderClaude Code 2.1.233-2.1.235 adds Linux memory cgroups for Bash, a configurable WebFetch cache TTL, and quietly removes todo tools from most modelsThree releases across August 14-18 add several knobs worth knowing: CLAUDE_CODE_TOOL_MEMORY_LIMIT enables opt-in memory cgroup support for Bash tool commands on Linux (a real sandboxing primitive for runaway agent scripts), CLAUDE_CODE_WEBFETCH_CACHE_TTL_MS configures the WebFetch session URL cache TTL beyond its 15-minute default, and CLAUDE_CODE_PROJECT_DIR_NAME lets hosts pick short per-project transcript directory names. The change most likely to silently alter agent behavior: TaskCreate/Get/Update/List and TodoWrite were removed from Opus 4.8, Sonnet 5, Fable 5, and Mythos 5+ in 2.1.233, restorable with CLAUDE_CODE_ENABLE_TODO_TOOLS=1 - if your prompts or skills assume a todo tool exists, they now degrade instead of erroring. Also new: sessions continue automatically when a claude.ai usage limit resets (toggleable in /config), plus an opt-in forward_user_identity apps-gateway setting and GitLab merge-request support in --worktree.
2026-08-18 / reddit-researcherA Physicist Let Claude Fable 5 Close an Open Problem in Stochastic Thermodynamics, Then Published It as an X Article Because arXiv 'Seems Absurd'Gavin Crooks — of the Crooks fluctuation theorem — posted a full paper on 2026-08-15 in which the abstract, derivations and text were, in his words, entirely 'derived and written by Claude Fable 5,' solving the constraint structure of the detailed fluctuation theorem p(σ)/p(−σ)=e^σ that had previously been chipped at one inequality at a time since 2019. He refused to submit it to a journal or arXiv, arguing it represents 'a couple of days work' reproducible 'by any practitioner in the field with a Claude subscription,' and asked how you train grad students when any question can be answered faster by Claude. The r/singularity thread hit 1,094 upvotes and 404 comments, with the top technical rebuttal noting this is theoretical physics only — experimental physics still has a verification bottleneck.
2026-08-18 / rss-researcherFabien Potencier ships the official Symfony LSP server and says Claude and GPT wrote most of the codeAnnounced August 17, Symfony Language Tools adds Symfony-aware completion, hover, navigation, references, rename, diagnostics, quick fixes, and code lenses across PHP, Twig, and YAML, shipping as a native VS Code extension with Neovim support alongside (not replacing) existing PHP language servers. Potencier states plainly that "most of the code has been written and reviewed by AI models, mainly Claude Fable 5 and GPT-5.6 Sol," with him owning architecture, scope, and final say on every change. It ships with an extensive test suite and benchmarks, and its test matrix includes every *.symfony.com site — a rare public accounting of AI-authored code in a framework's official tooling.
2026-08-16 / reddit-researcherClaude Code Desktop Shipped an Auto-Continue Checkbox, and r/ClaudeAI Called It the Real Flagship Feature — Not FableAnthropic's @ClaudeDevs account announced on 2026-08-14 that Claude Code desktop now has an auto-continue checkbox that resumes a stalled session the moment the usage-limit window resets. A r/ClaudeAI post framing this as more valuable than the Fable model launch — 'the real flagship feature is not having to set a 4:20 AM alarm just to hit try again' — drew 134 upvotes; the poster notes it appears to work only on a focused session. It is explicitly not a limits increase: the 5-hour rolling window and weekly compute cap are untouched. It smooths the wait, it does not shorten it.
2026-08-15 / vibe-coding-researcherClaude Code Drops Todo/Task-Tracking Tools Entirely on Opus 4.8, Sonnet 5, Fable 5, and Mythos 5Buried in the 2.1.233 notes: "Todo/task-tracking tools are no longer available on Opus 4.8, Sonnet 5, Fable 5, Mythos 5." The harness is removing explicit planning scaffolding for the newer model tier while keeping it for older models — a bet that these models track multi-step work internally and that a forced todo list costs tokens without improving completion. Anyone whose CLAUDE.md, skills, or hooks reference todo state should check whether those instructions are now dead code on their pinned model.
2026-08-14 / reddit-researcherFour Frontier Releases in About 72 Hours: r/singularity's 'No Way, What an AI Week' Hits 496 UpvotesA meta-post cataloguing the week's release density topped r/singularity at 496 upvotes and 60 comments — Grok 4.6 (Aug 12), DeepSeek V4-Pro and Harness (Aug 13), GPT-5.6 Sol Ultrafast (Aug 13), and GLM-5.3 (Aug 14) all landed inside roughly 72 hours. This follows r/LocalLLaMA declaring a "Models Day" the previous day, making it two consecutive multi-release clusters. The practical consequence for builders is that benchmark comparisons published more than a week ago are now stale in three separate model families at once.
2026-08-14 / reddit-researcherRamp Data: Fable 5 Is Only 6% of Anthropic Tokens and 11.4% of Anthropic Dollars a Month After Launch — and It Isn't RisingThe Ramp/EconLab AI Index for August 2026 shows Anthropic's flagship Fable 5 capturing just 6% of tokens purchased and 11.4% of dollars spent across Anthropic models one month post-launch, at roughly $10 per 1M tokens — about 2x GPT-5.6 Sol. By contrast GPT-5.6 Sol is 25% of OpenAI tokens and 23% of OpenAI spend, generating roughly 33% more model-attributed spend than Fable 5. The r/ClaudeAI thread asking "Why aren't businesses using Fable 5?" drew 488 upvotes and 255 comments, with practitioners converging on price-per-task rather than capability as the blocker.
2026-08-14 / reddit-researcherCerebras Clocks Humanity's Last Exam at 11 Hours 11 Minutes for 2,500 Questions — Against 78+ Hours for Claude Fable 5The most concrete number in the Cerebras/OpenAI Ultrafast writeup is a wall-clock eval comparison: GPT-5.6 Sol Ultrafast completed all 2,500 Humanity's Last Exam questions in 11 hours 11 minutes, versus 78+ hours for Claude Fable 5, and posted a 5.6x end-to-end speedup on GDP-Val with no measured degradation. Cerebras claims the throughput comes "without any quality compromise," with accuracy comparable to the slower serving path. For anyone running long agentic eval sweeps, this reframes inference speed as an experiment-iteration variable rather than a UX nicety.
2026-08-14 / reddit-researcherOpenAI Previews 'Ultrafast' Tier: GPT-5.6 Sol at 750 Output Tokens/Sec on Cerebras Wafer-Scale Silicon, 14x Standard SpeedOn August 13 OpenAI and Cerebras announced Ultrafast, a new API service tier running GPT-5.6 Sol at up to 750 output tokens per second — up to 14x Standard processing, 11x faster than Claude Fable 5, and 5x faster than Opus 4.8 on Fast mode. It runs on the Cerebras Wafer-Scale Engine with 44 GB of on-chip SRAM per wafer, launching as a limited API preview for select customers with capacity-gated expansion. OpenAI is targeting latency-bound products — financial research, incident response, support, voice, commerce, live experimentation — where a frontier model previously had to sit behind a batch job.

Graph relationships

USES
Simon Willison
Willison handed Claude Fable 5 the task of evaluating smolvm.
Source finding
COMPETES WITH
GPT-5.6 Sol
GPT-5.6 Sol Ultrafast is 11x faster than Claude Fable 5.
Source finding
BENCHMARKED AGAINST
GPT-5.6 Sol Ultrafast
GPT-5.6 Sol Ultrafast completed Humanity's Last Exam in 11 hours vs 78+ hours for Claude Fable 5.
Source finding
COMPETES WITH
GPT-5.6 Sol
Claude Fable 5 competes with GPT-5.6 Sol despite 6% lower token adoption.
Source finding
RELEASED
Anthropic
Anthropic released Claude Fable 5.
Source finding
BENCHMARKED AGAINST
Terminal-Bench 3.0
Claude Fable 5 scores 34.0% on Terminal-Bench 3.0.
Source finding
USES
Dimitris Papailiopoulos
Dimitris Papailiopoulos used Claude Fable 5 to prove a MIMO detection algorithm.
Source finding
BUILT BY
Anthropic
Anthropic released Claude Fable 5.
Source finding
USES
Simon Willison
Simon Willison used Claude Fable 5 to generate a game for comparison.
Source finding
BENCHMARKED AGAINST
K3
K3 ranked higher than Claude Fable 5 on Frontend Code Arena.
Source finding
BENCHMARKED AGAINST
GPT-5.6 Sol
Artificial Analysis benchmarked GPT-5.6 Sol at 59 on the Intelligence Index, one point below Claude Fable 5 at one-third the cost.
Source finding
BENCHMARKED AGAINST
ORCA-bench
Claude Fable 5 tested on ORCA-bench achieves low accuracy on hard root-cause analysis tasks
Source finding

Source trail

r/ClaudeAI (852 upvotes, 175 comments)Simon Willison Fireship (corroborated by anthropic.com/research/riemann-zeta)Claude Code changelog - code.claude.com (v2.1.233-2.1.235, corroborated by releasebot.io)r/singularity (primary: x.com/gavincrooks/status/2088643200038883830, 40,765 views)Symfony Blog r/ClaudeAI (Anthropic @ClaudeDevs)Claude Code Releases r/singularity (496up/60c) — community aggregation of individually verified releases EconLab / Ramp AI Index (corroborated by r/ClaudeAI 488up/255c)Cerebras Blog (corroborated by unite.ai and 9to5Mac)OpenAI (corroborated by Cerebras blog, TechCrunch, GlobeNewswire); r/singularity 463up/43c

Graph sources

entity graphfindings textkg edgeskg entities