Boris Cherny
A builder or AI practitioner mentioned for using Claude to automate Slack outreach and response tracking. This is relevant to PMs as an example of agent-driven workflow automation.
Key Highlights
- Boris Cherny is repeatedly cited for practical Claude and Claude Code workflows rather than abstract AI commentary.
- His Slack direct-message and response-tracking example is a clear illustration of agent-driven workflow automation for business tasks.
- He emphasized operational debugging with `/usage`, pointing PMs toward observability for token spend, loops, and inefficient skills.
- He announced and discussed Claude Mods, framing extensibility and shareable customization as an important product direction.
- He demonstrated using Opus 5.5 with Lean on the Claude Agent SDK to generate PRs addressing bugs and race conditions.
At a glance
- Role
- Builder
- Company
- Independent
- X / Twitter
- @boris
Overview
Boris Cherny is a builder and AI practitioner frequently mentioned in connection with Claude, Claude Code, and agent-driven workflows. Across newsletter mentions, he appears as a hands-on operator and product-facing technical voice discussing how Anthropic tools are used in practice: from automating Slack outreach and tracking replies, to debugging usage spikes, to extending Claude Code with mods and plugins.
For AI Product Managers, Boris Cherny matters as an example of the emerging practitioner who sits at the intersection of product, engineering, and agent operations. His mentions illustrate practical themes PMs care about: workflow automation with agents, extensibility as a product lever, model-assisted software verification, performance optimization, enterprise guardrails, and the operational realities of managing cost, safety, and reliability in agentic systems.
Key Developments
- 2026-08-21: Boris Cherny recommended running `/usage` for a detailed breakdown of consumption, saying problems are often caused by extreme parallelism, a runaway loop, or an inefficient skill/plugin.
- 2026-08-21: He also said an unnamed item, developed with customers, was expected in the fall, while noting that Mythos-class models need additional safety measures and enterprise customers need privacy and compliance controls with customer-owned data.
- 2026-08-24: Cherny described model progress across coding, coding-adjacent engineering, and broader computer-based tasks, saying Claude had reached stage 1, part of stage 2, and early signs of stage 3 in his workflow.
- 2026-08-24: He said he stopped writing code by hand in November 2025 but still codes daily with agents, and that Opus 4.8 was the first model that felt better than him at coding, while still producing bugs and inefficiencies.
- 2026-08-24: He noted that Opus is strong at long-running work and coding, but verbosity is a major issue; as a workaround, users could set `claude /config outputStyle=concise`.
- 2026-08-25: Cherny said his group uses the same exact Fable and is working to reduce cybersecurity refusals.
- 2026-09-04: He requested feedback on an early concept for making Claude Code more extensible, describing it as unusual but exciting.
- 2026-09-15: Cherny announced that Claude Mods were landing for Claude Code, highlighting customizations such as a Tetris-in-Claude mod.
- 2026-09-23: He demonstrated using Opus 5.5 with Lean to formally verify the Claude Agent SDK, saying a few short prompts generated 16 PRs that addressed bugs and race conditions.
- 2026-09-24: Cherny shared a post on how the claude.ai login flow and Desktop app became faster, positioning it as useful for engineers trying to speed up their own apps.
- 2026-09-24: He also said Claude can model tricky state machines or race-prone code, identify counter-examples as suspected bugs, reproduce them, and fix the code, while clarifying this is not full formal verification of an entire codebase.
- 2026-10-02: Cherny announced Claude Mods more broadly, describing them as a way to customize how Claude works and looks through prompting, with shareable mods functioning like plugins.
- 2026-10-05: He again recommended `/usage` for a token-by-token breakdown, saying excessive usage is usually due to a runaway loop or an inefficient skill.
- 2026-10-08: Cherny said he has Claude direct-message people on Slack, monitor responses, and generate a chart of the results, showing a concrete agent-driven outreach workflow.
Relevance to AI PMs
1. Agent workflow design and automation
Cherny's Slack outreach example is a concrete pattern for PMs designing agentic products: give the agent a goal, connect it to a communication channel, monitor outcomes, and convert activity into structured reporting. This is directly relevant for customer research, sales assist, recruiting, and internal ops use cases.
2. Operational controls for cost and reliability
His repeated advice to inspect `/usage` and look for runaway loops, extreme parallelism, or inefficient skills is a practical reminder that agent products need observability. PMs should define safeguards around token usage, tool-calling behavior, concurrency, and plugin efficiency early in product design.
3. Extensibility and ecosystem strategy
Cherny's work on Claude Mods and Claude Code extensibility highlights how customization can expand product value. For PMs, this suggests a roadmap pattern: start with a core assistant experience, then unlock adoption and retention through reusable mods, plugins, and domain-specific skills.
Related
- Anthropic: Cherny is repeatedly mentioned in connection with Anthropic product updates and developer workflows around Claude and Claude Code.
- Claude / claude.ai: The primary model and product surface tied to his examples, including Slack automation, usage analysis, and app performance improvements.
- Claude Code: A major area of his mentions, especially around extensibility, mods, and coding workflows.
- Claude Mods / plugins: Closely connected to his announcements about customizing Claude's behavior and sharing those customizations.
- Claude Agent SDK: Featured in his example of using Opus 5.5 and Lean to find bugs and race conditions through formal verification-style workflows.
- Lean: Connected through his demonstration of model-assisted verification work on the Claude Agent SDK.
- Fable: Mentioned in relation to his group's usage and efforts to reduce cybersecurity refusals.
- Usage: A recurring operational topic in his comments, especially token breakdowns and debugging expensive or looping behavior.
- Slack: Central to his showcased automation use case where Claude messages users, tracks responses, and creates charts.
- LangChain / LiteLLM / RAG / agentic-search: Related ecosystem concepts and tooling relevant to the broader agent and workflow automation space in which his mentions sit.
- Bedrock / Vertex / Azure: Related enterprise model deployment surfaces that matter in the same PM conversations around enterprise access, compliance, and model operations.
Frequently asked questions
What is Boris Cherny?
A builder or AI practitioner mentioned for using Claude to automate Slack outreach and response tracking. This is relevant to PMs as an example of agent-driven workflow automation.
What should AI product managers know about Boris Cherny?
Boris Cherny is repeatedly cited for practical Claude and Claude Code workflows rather than abstract AI commentary. His Slack direct-message and response-tracking example is a clear illustration of agent-driven workflow automation for business tasks. He emphasized operational debugging with `/usage`, pointing PMs toward observability for token spend, loops, and inefficient skills.
Newsletter Mentions (40)
“#20 𝕏 Boris Cherny says he has Claude direct-message people on Slack, monitor their responses, and create a chart with the results.”
#20 𝕏 Boris Cherny says he has Claude direct-message people on Slack, monitor their responses, and create a chart with the results.
“He recommended running `/usage` for a token-by-token breakdown, noting that excessive usage is most often caused by a runaway loop or inefficient skill.”
#10 𝕏 Boris Cherny said there were no changes on their end and usage is monitored carefully. He recommended running `/usage` for a token-by-token breakdown, noting that excessive usage is most often caused by a runaway loop or inefficient skill.
“Boris Cherny announced Claude mods, which let users customize how Claude works and looks through prompting. Mods can also be shared as plugins for others to try.”
#2 𝕏 Boris Cherny announced Claude mods, which let users customize how Claude works and looks through prompting. Mods can also be shared as plugins for others to try.
“Boris Cherny shared a blog post explaining how the claude.ai login experience and Desktop app became faster in the last few weeks, with techniques for engineers speeding up their own apps.”
#8 𝕏 Boris Cherny shared a blog post explaining how the claude.ai login experience and Desktop app became faster in the last few weeks, with techniques for engineers speeding up their own apps. #9 𝕏 Boris Cherny commented that Claude appears to model tricky state machines or race-prone code, identify counter-examples as suspected bugs, reproduce them, and fix the code. He clarified that this targets the hardest parts rather than formally verifying the entire codebase.
“#5 𝕏 Boris Cherny demonstrated using Opus 5.5 to formally verify the Claude Agent SDK with Lean, saying a couple short prompts produced 16 PRs addressing bugs and race conditions.”
GenAI PM Daily September 23, 2026 GenAI PM Daily 🎧 Listen to this brief 3 min listen Today's top 20 insights for PM Builders, ranked by relevance from Blogs, X, and YouTube. OpenAI News announces GPT-6 Sol and Luna #1 📝 OpenAI News Introducing GPT-6 Sol and Luna - Introduces two new GPT-6 variants, Sol and Luna, highlighting their capabilities and intended use cases. The announcement describes distinctions between the models and how organizations can adopt them. Also covered by: @Cognition , @OpenAI , @Sam Altman , @There's An AI For That #2 𝕏 Claude Opus 5.5 is available today. Also covered by: @Thariq , @Mike Krieger , @Anthropic , @Aravind Srinivas , @Cursor , @v0 , @Claude , @There's An AI For That #3 📝 OpenAI News Better prompt caching for GPT-6 - Announces improvements to prompt caching for GPT-6 to reduce latency and cost for repeat prompts, improving developer and product performance. #4 𝕏 Aravind Srinivas shared research on a post-training approach that teaches the Perplexity Computer agent from real user sessions by combining rejection sampling fine-tuning with hint-guided self-distillation. #5 𝕏 Boris Cherny demonstrated using Opus 5.5 to formally verify the Claude Agent SDK with Lean, saying a couple short prompts produced 16 PRs addressing bugs and race conditions.
“Anthropic announces Claude Mods for Claude Code #1 𝕏 Boris Cherny announced that Anthropic’s Claude Mods are landing now, highlighting a Tetris-in-Claude mod.”
GenAI PM Daily September 15, 2026 GenAI PM Daily 🎧 Listen to this brief 3 min listen Today's top 20 insights for PM Builders, ranked by relevance from X, YouTube, and LinkedIn. Anthropic announces Claude Mods for Claude Code #1 𝕏 Boris Cherny announced that Anthropic’s Claude Mods are landing now, highlighting a Tetris-in-Claude mod. The linked anthropics/claude-code issue includes the latest community update, technical details, and additional demos. #2 𝕏 Google DeepMind shared a Google Blog link about WeatherNext 3, noting that advance visibility into rapidly changing weather helps teams balance power grids and match clean energy to everyday consumer demand. Also covered by: @Google DeepMind #3 𝕏 Google AI shared Dreambeans from Google Labs, an opt-in experience that connects information across Gmail, Calendar, Search, Gemini, and Google Photos face grouping to generate customized illustrated stories and relevant next steps. Daily in-app notifications surface new stories, while privacy filters and thumbs-down feedback give users control over personalization. #4 𝕏 NVIDIA announced new SDKs, NIM microservices, playbooks and blueprints for its AI for Media collection at IBC2026. The tools can help verify potentially AI-generated footage, create smoother slow-motion sports replays and translate programming with lip-synced dubbing. #5 𝕏 Aravind Srinivas announced expanded work with NVIDIA to bring fully local, unmetered AI to Microsoft Windows PCs with RTX GPUs using NVIDIA hardware and a Perplexity harness. #6 𝕏 DeepLearning.AI recapped GPT-6 Astra, reporting that it tops the ARC-AGI-3 leaderboard while cutting token costs and ties Claude Fable 5.1 on Artificial Analysis’ Intelligence Index. For builders, it highlights asynchronous tool calls, retained reasoning memory across API calls, and efficient context management for scaling agents. #7 𝕏 NVIDIA AI shared an engineering deep dive on tuning caching, memory, parallelism, decoding and more for the Nemotron 3 Ultra NIM. On four B200 GPUs, these optimizations supported up to 2.5x more concurrent users while maintaining 50 TPS/user. #8 ▶️ Building a Software Factory that actually works (Full Course) Greg Isenberg The software factory uses five or six markdown files to run an agent workflow of isolate, build, prove, and ship: fresh Git work trees from origin main, service-layer code structure, before-and-after evidence, and Greptile PR review loops to a five-out-of-five score. Each feature starts in a fresh Git work tree branched from origin main ; separate agents work in separate copies of the app, and completed changes are merged back after the work tree is finished. The code structure skill directs agents to use a service layer architecture, while evidence-driven testing records a broken before state and a working after state as video or screenshots in the pull request. For a performance change, page-load time was reduced from 815 milliseconds to about 61 milliseconds; Greptile feedback below five out of five sends the agent back through build, prove, and ship until the PR reaches five out of five. #9 𝕏 LlamaIndex 🦙 shared a two-pass, just-in-time OCR workflow for ad-hoc data rooms: LiteParse provides a layout-aware first pass across 50+ formats—reportedly processing a full data room in 32 seconds—while LlamaParse handles only pages needing deeper extraction. The approach aims to avoid the cost and latency of parsing every page upfront. #10 𝕏 Radio lets agents in Claude Code, Codex, or Cursor communicate in real time across machines by pasting one link. Agents get their own channel, where humans can answer questions or redirect work. #11 𝕏 Harrison Chase said Slack is where agents are doing work and that Managed Deep Agents has a tight Slack integration. He shared a tutorial about the integration. #12 𝕏 Guillermo Rauch said agents are only as effective as their proof-checkers, compilers, type systems, and linters, highlighting shadcn/lint as a way to keep agents aligned with design-system rules. He characterized verifiers and skills as the new “frameworks.” #13 𝕏 Santiago said the Cline desktop app is available, open-source, and usable with open-weight models. He argued that agentic coding tools are shifting from terminal interfaces to desktop apps with better affordances. #14 in Peter Yang shared a video showing how to set up the 11 Grok Bots he currently uses: 3 for orchestration, long-term planning, and bot maintenance; 3 for growing his business; and 5 for saving time and money and improving his life. The video also shows the bots talking to one another. #15 𝕏 claire vo 🖤 shared a link to a clairevo.com page about building a cursor-following portrait with Flora and Codex. #16 𝕏 Thariq shared a conversation with Sid and Robert about building Claude Code, covering how much things have changed, the challenge of keeping up with model capabilities, and what they miss about software engineering before AI. #17 in Claire Vo recapped a How I AI episode with John Bai and Peng Zheng about the GrokBot design team’s use of AI agents. Demonstrations include a hyper-personal homepage maintained by Grok Bot, Figma Bro handling design production, and voice memos turned into production code. #18 in Greg Isenberg commented that agent harnesses loop models, provide tool and file access, manage memory, enforce rules, and retain job knowledge so builders can switch models and improve workflows through human corrections. He argues they could support outcome-based pricing across many of 800+ occupations, with OpenAI’s Agents API, Claude’s managed agents, Vercel’s eve, and LangChain making them easier to build. #19 𝕏 Peter Yang recapped Brex CEO Pedro’s view that good AI products pair an agentic loop with tools exposed to a model. As an example, Brex built Jim, an AI recruiter that uses Greenhouse, LinkedIn, and other software to automatically deliver qualified candidates. #20 𝕏 Sam Altman commented that American companies developing increasingly capable AI must act responsibly and that every frontier lab should provide confidence in its conduct. He discussed federal frameworks, Responsible Scaling Policies, safety cases for frontier reinforcement-learning runs, pacing progress, alignment and monitoring, and international coordination. Found this valuable? Share it with another PM - they can subscribe at genaipm.com Unsubscribe • Switch to Weekly
“Boris Cherny requested feedback on an early concept for making Anthropic’s Claude Code more extensible, describing it as “a little crazy, and very exciting.””
Boris Cherny requested feedback on an early concept for making Anthropic’s Claude Code more extensible, describing it as “a little crazy, and very exciting.” More details are available in issue 91870 of the anthropics/claude-code GitHub repository.
“Boris Cherny said his unspecified group uses the same exact Fable and is working to reduce cybersecurity refusals.”
GenAI PM Daily August 25, 2026 GenAI PM Daily 🎧 Listen to this brief 3 min listen Today's top 19 insights for PM Builders, ranked by relevance from Blogs, YouTube, and LinkedIn. GPT-5.6 in Kiro advances developer price-performance #1 📝 OpenAI News Advancing price-performance for developers with GPT‑5.6 in Kiro to improve price-performance for developers, enabling more cost-effective and performant model access for applications. #16 𝕏 Boris Cherny said his unspecified group uses the same exact Fable and is working to reduce cybersecurity refusals.
“He stopped writing code by hand in November 2025 but still codes daily with agents, and said Opus 4.8 was the first model that felt better than him at coding, while stressing that Claude’s code still has bugs and inefficiencies.”
#7 𝕏 Boris Cherny commented that models are advancing through three stages—coding, coding-adjacent engineering, and most computer-based tasks—and judged Claude to have reached stage 1, part of stage 2, and early signs of stage 3 for his work. He stopped writing code by hand in November 2025 but still codes daily with agents, and said Opus 4.8 was the first model that felt better than him at coding, while stressing that Claude’s code still has bugs and inefficiencies. #10 𝕏 Boris Cherny said Opus excels at long-running work and coding but has quirks, with verbosity a major concern and broader fixes a team priority. As a temporary mitigation, users can run `claude /config outputStyle=concise`.
“Boris Cherny recommended running `/usage` for a detailed breakdown, noting that the issue is most often caused by extreme parallelism, a runaway loop, or a very inefficient skill/plugin.”
#14 𝕏 Boris Cherny recommended running `/usage` for a detailed breakdown, noting that the issue is most often caused by extreme parallelism, a runaway loop, or a very inefficient skill/plugin. #16 𝕏 Boris Cherny announced that an unnamed item, which had been worked on with customers for a while, was expected to arrive in the fall. He said Mythos-class models require additional safety measures, enterprises need to meet their own privacy and compliance rules, and customers can own and control their data while Anthropic retains none of it.
Related
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Anthropic’s coding agent/environment used here to control physical tools in a long-running home experiment.
Anthropic’s AI assistant, referenced here through new dashboard, motion, docs, slides, and design capabilities.
The company behind LangSmith, mentioned in connection with trajectory labeling and evaluation workflows. Relevant to AI PMs building agent monitoring stacks.
A Claude model version praised for personality and writing style. The newsletter contrasts it with Opus 5 as more concise and friend-like.
An AI tool used in Every’s copy-editing benchmark to create an agent from historical edits. Relevant to AI PMs for agent evaluation and workflow automation.
A security risk where malicious instructions manipulate agent behavior. The newsletter references it in the context of skill/repo scanning tools.
A model used in the newsletter as a reasoning and execution engine for product experimentation. It is described as generating daily A/B test ideas and implementing winners for a mobile game economy.
RAG is a retrieval-based pattern that injects external context into prompts to improve model responses. The newsletter presents it as often outperforming fine-tuning for practical product work.
Anthropic's SDK for building Claude-powered agents and workflows. In the newsletter it is used in a formal verification example with Lean and TLA+.
A Claude model used in the newsletter's example to run Python code and analyze a floor plan. It is discussed as part of an agentic workflow inside Claude Cowork.
An AI-powered code review feature from Claude Code designed to provide deep PR feedback, catch bugs, and improve development workflows. It is presented as a research-preview beta for Team and Enterprise.
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