Talk to users. Build the thing
fstack is a dual-engine skill stack for founders who still write the product. One router classifies the request: founder operations (inbound leads, support, social, strategy, competitive teardown) or engineering (/engineer-mode with 23 playbooks and 24 principles). More
Skills 75 in the ChatGPT listing
architect Sketch types, signatures, and module structure before code, then stay in the loop while implementation fills in. arena Spawn N parallel candidates at the same task, pick a base, graft the strongest parts of the losers into it. Automate me Use for "automate me", "create/update/refresh my -mode skill", "turn/capture my preferences or working style into a skill", or wanting agents to follow how the user works. babysit Watch an open PR — fix failing CI, handle the straightforward review comments, and drive it to a mergeable state. Blast radius Find what a change could break somewhere else before it ships, beyond the diff, and prove the one fact it's safe because of by running real code instead of writing it up. bro Restate the last message in plain human language, with no jargon. browse Web browsing and page extraction. Ceo review Founder/CEO strategic plan review. Changelog to post Converts git commits, PR diffs, or engineering release notes into clean, user-facing changelogs, customer update emails, and launch tweets. Create verification skill Generate a project-local verification skill that drives your app the way a user does — any language, framework, or platform. Customer lens Audits UI flows, onboarding funnels, error messages, and landing page copy from the perspective of a skeptical, distracted customer. deslop Remove AI-generated code slop and clean up code style Engineer mode fstack engineering execution. Figure it out Design an auditable playbook when no narrower one fits: a large migration, an ambitious multi-part change, or work a human reviews after stepping away. Fix ci Find failing PR checks, inspect logs or external check links, and apply focused fixes Fix merge conflicts Resolve merge conflicts non-interactively, validate build and tests, and finalize conflict resolution Founder mode High-agency founder execution mode. Founder voice Manages and maintains the founder's persistent voice profile, tone preferences, vocabulary rules, and platform styles across X and LinkedIn. fstack Master orchestrator for fstack. Geo page Generates high-authority GEO (Generative Engine Optimization) and documentation pages designed to be accurately cited by AI search engines (Perplexity, SearchGPT, ChatGPT, Gemini) without keyword-stuffed SEO slop. Get pr comments Fetch and summarize review comments from the active pull request how Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions ("where should this live", "which package owns this", "is this the right layer"). Inbox triage Ingests pasted email threads or inbox batches, ranks by business and customer urgency, surfaces top priorities, and generates concise notes and 1-click draft responses. interrogate Use for "interrogate", "adversarial review", "multi-model review", "challenge this", "stress test this code", "find blind spots", or "tear this apart". Lead reply Draft high-conversion, charming, consultative, and non-salesy replies to inbound leads and inquiries. Maintain verification skill Periodic pass that keeps a project's verification skill and feature map honest: parallel source readers per feature, one live session driving every feature, at most one PR of proven corrections. Make pr easy to review Prepare PRs for review by cleaning noisy history, improving PR descriptions, and adding reviewer guidance without changing code behavior. No comments Spawn the comment-sicko subagent, fix accepted findings, and offer encodings for claimed constraints. Office hours YC-style founder sparring and product interrogation. Poteto mode Compatibility alias for /engineer-mode and credit to Lauren Tan's pstack, which set the foundation of playbooks and principles for fstack's engineer-mode. Principle attack the premise Apply when two or more fixes that share one premise have failed the same gate. Principle boundary discipline Apply when wiring validation, error handling, or framework adapters. Principle build the lever Apply to any non-trivial work, not just bulk work: edits, migrations, analyses, checks. Principle clear naming Apply when naming variables, functions, types, files, or endpoints. Principle encode lessons in structure Apply when you catch yourself writing the same instruction a second time, or notice a recurring correction. Principle exhaust the design space Apply when facing a novel UI interaction or architectural decision with no precedent in the codebase. Principle experience first Apply when product, UX, or feature-scope tradeoffs come up. Principle fix root causes Apply when debugging. Principle foundational thinking Apply before writing logic: choosing core types and data structures, sequencing scaffold-vs-feature work, asking what concurrent actors share. Principle guard the context window Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Principle laziness protocol Apply when refactoring, evaluating diff size, or tempted to add abstractions, layers, or signal threading. Principle make operations idempotent Apply when designing commands, lifecycle steps, or processing loops that run amid crashes, restarts, and retries. Principle migrate callers then delete legacy apis Apply when introducing a new internal API while old callers still exist. Principle minimize reader load Apply when reviewing or shaping code that's hard to trace. Principle model the domain Apply when writing stateful logic, or when code branches a lot or repeats a shape assumption across files. Principle never block on the human Apply when tempted to ask 'should I do X?' on reversible work. Principle outcome oriented execution Apply during planned rewrites and migrations with explicit phase boundaries. Principle prove it works Apply after completing a task, before declaring done. Principle redesign from first principles Apply when integrating a new requirement into an existing design. Principle separate before serializing shared state Apply when concurrent actors might write to the same file, branch, key, or state object. Principle sequence verifiable units Apply to multi-step work (sweeps, migrations, runs of similar edits) and to how you stack commits and PRs. Principle subtract before you add Apply when sequencing an addition, refactor, or rewrite. Principle test behavior not implementation Apply when you write, change, or keep a test. Principle type system discipline Apply when designing types, reviewing a function signature, or writing code in any statically-typed language. recall Reconstruct your recent working context from your own chat history, live state, and the shared record (user reports, prior fixes, incidents), then hand back a tight current-state brief. reflect Spawn three parallel review subagents over the active transcript, surface learnings, and route each to a concrete edit on an existing skill. retro Weekly founder momentum, engineering velocity, customer feedback, and tech debt review. Setup fstack Configure which models fstack uses per role and at what reasoning budget. Show me your work Keep a reviewable decision trail for long-running or unattended work: a TSV log with one row per decision (what, why, evidence, result). Social post Drafts authentic, high-signal social media posts from founder thoughts, engineering wins, or product updates. Social reply Crafts high-leverage, non-slop replies to trending and viral posts on X and LinkedIn. stfu Forces ultra-terse, zero-chatter, quiet execution mode. sudo Root operator execution override. Support loop End-to-end founder customer support loop. swarm Fan out N parallel workers, drain them, and return one report. tdd Use only when the user explicitly asks for TDD, a failing test, or a regression test, OR when the bug has an obvious cheap local test target. teach Explain a body of work plainly so a person actually understands it. teardown Conducts deep competitor, product, and pricing teardowns using web browsing and market intelligence. Technical writing Layered technical-writing standard: Diátaxis structure, Google developer style sentences, STE instruction rules, Global English syntax. Thermo nuclear code quality review Run an extremely strict maintainability review for abstraction quality, giant files, and spaghetti-condition growth. Typescript best practices TypeScript best practices. unslop Cut AI tells from any writing. Unslop email De-slop and humanize email drafts. What did i get done Summarize authored commits over a user-specified time period into a concise update why Use for 'why does X work this way', 'why we picked Y', design rationale, regressions, postmortems, or data-backed thresholds. 
