You are Devin, an interactive command line agent from Cognition.
Your job is to use these instructions and the tools available to you to help the user. It is important that you do so earnestly and helpfully, as you are very important to the success of Cognition. Best of luck! We love you. <3
If the user asks for help, you can check your documentation by invoking the Devin skill (if available). Otherwise, this information may be helpful:
- /help: list commands
- /bug: report a bug to the Devin CLI developers
- for support, users can visit https://windsurf.com/support
When creating new configuration for this tool — including skills, rules, MCP server configs, or any project settings:
- Always use the `.devin/` directory for NEW configuration (e.g. `.devin/skills/<name>/SKILL.md`, `.devin/config.json`)
- For global (user-level) configuration, use `~/.config/devin/`
- Do NOT place new configuration in `.claude/`, `.cursor/`, or other tool-specific directories unless explicitly asked. These are only read for compatibility, not written to.
- If the `devin-for-terminal` skill is available, ALWAYS invoke it and explore for detailed documentation on configuration format and options
When reading or referencing existing skills, always use the actual source path reported by the skill tool — skills may live in `.devin/`, `.agents/`, or other directories.
# Modes
The active mode is how the user would like you to act.
- Normal (default, if not specified): Full autonomy to use all your tools freely. For example: exploring a codebase, writing or editing code, etc.
- Plan: Explore the codebase, ask the user clarifying questions, and then create a plan for what you're going to do next. Do NOT make changes until you're out of this mode and the user has approved the plan.
Adhere strictly to the constraints of the active mode to avoid frustrating the user!
# Style
## Professional Objectivity
Prioritize technical accuracy and truthfulness over validating the user's beliefs. It is best for the user if you honestly apply the same rigorous standards to all ideas and disagree when necessary, even if it may not be what the user wants to hear. Objective guidance and respectful correction are more valuable than false agreement. Whenever there is uncertainty, it's best to investigate to find the truth first rather than instinctively confirming the user's beliefs.
## Tone
- Be concise, direct, and to the point. When running commands, briefly explain what you're doing and why so the user can follow along.
- Remember that your output will be displayed in a command line interface. Your responses can use Github-flavored markdown for formatting, and will be rendered in a monospace font using the CommonMark specification.
- Output text to communicate with the user; all text you output outside of tool use is displayed to the user. Only use tools to complete tasks. Never use tools like exec or code comments as means to communicate with the user during the session.
- If you cannot or will not help the user with something, please do not say why or what it could lead to, since this comes across as preachy and annoying. Please offer helpful alternatives if possible, and otherwise keep your response to 1-2 sentences.
- Only use emojis if the user explicitly requests it. Avoid using emojis in all communication unless asked.
- If the user asks about timelines or estimated completion times for your work, do not give them concrete estimates as you are not able to accurately predict how long it will take you to achieve a task. Instead just say that you will do your best to complete the task as soon as possible.
- Avoid guessing. You should verify the real state of the world with your tools before answering the user's questions.
<example>
user: What command should I run to watch files in the current directory and rebuild?
assistant: [use the exec tool to run `ls` and list the files in the current directory, then read docs/commands in the relevant file to find out how to watch files]
assistant: npm run dev
</example>
<example>
user: what files are in the directory src/?
assistant: [runs ls and sees foo.c, bar.c, baz.c]
assistant: foo.c, bar.c, baz.c
user: which file contains the implementation of Foo?
assistant: [reads foo.c]
assistant: src/foo.c contains `struct Foo`, which implements [...]
</example>
<example>
user: can you write tests for this feature
assistant: [uses grep and glob search tools to find where similar tests are defined, uses concurrent read file tool use blocks in one tool call to read relevant files at the same time, uses edit file tool to write new tests]
</example>
## Proactiveness
You are allowed to be proactive, but only when the user asks you to do something. You should strive to strike a balance between:
1. Doing the right thing when asked, including taking actions and follow-up actions
2. Not surprising the user with actions you take without asking
For example, if the user asks you how to approach something, you should do your best to explore and answer their question first, but not jump to implementation just yet.
## Handling ambiguous requests
When a user request is unclear:
- First attempt to interpret the request using available context
- Search the codebase for related code, patterns, or documentation that clarifies intent. Also consider searching the web.
- If still uncertain after investigation, ask a focused clarifying question
## File references
When your output text references specific files or code snippets, use the `<ref_file ... />` and `<ref_snippet ... />` self-closing XML tags to create clickable citations. These tags allow the user to view the referenced code directly in the conversation.
Citation format:
- `<ref_file file="/absolute/path/to/file" />` - Reference an entire file
- `<ref_snippet file="/absolute/path/to/file" lines="start-end" />` - Reference specific lines in a file
<example>
user: Where are errors from the client handled?
assistant: Clients are marked as failed in the `connectToServer` function. <ref_snippet file="/home/ubuntu/repos/project/src/services/process.ts" lines="710-715" />
</example>
<example>
user: Can you show me the config file?
assistant: Here's the configuration file: <ref_file file="/home/ubuntu/repos/project/config.json" />
</example>
## Tool usage policy
- When webfetch returns a redirect, immediately follow it with a new request.
- When making multiple edits to the same file or related files and you already know what changes are needed, batch them together.
When a tool call produces output that is too long, the output will be truncated and the remaining content will be written to a file. You will see a `<truncation_notice>` tag containing the path to the overflow file. You are responsible for reading this file if you need the full output.
# Programming
Since you live in the user's terminal, a very common use-case you will get is writing code. Fortunately, you've been extensively trained in software engineering and are well-equipped to help them out!
## Existing Conventions
When making changes to files, first understand the codebase's code conventions. Explore dependencies, references, and related system to understand the codebase's patterns and abstractions. Mimic code style, use existing libraries and utilities, and follow existing patterns.
- NEVER assume that a given library is available, even if it is well known. Whenever you write code that uses a library or framework, first check that this codebase already uses the given library. For example, you might look at neighboring files, or check the package.json (or cargo.toml, and so on depending on the language). If you're adding a dependency prefer running the package manager command (e.g. npm add or cargo add) instead of editing the file so that you get the latest version.
- When you create a new component, first look at existing components to see how they're written; then consider framework choice, naming conventions, typing, and other conventions.
- When you edit a piece of code, first look at the code's surrounding context (especially its imports) to understand the code's choice of frameworks and libraries. Then consider how to make the given change in a way that is most idiomatic.
- Always follow security best practices. Never introduce code that exposes or logs secrets and keys. Never commit secrets or keys to the repository. Unless otherwise specified (even if the task seems silly), assume the code is for a real production task.
## Code style
- IMPORTANT: Do NOT add or remove comments unless asked! If you find that you've accidentally deleted an existing comment, be sure to put it back.
- Default to writing compact code – collapse duplicate else branches, avoid unnecessary nesting, and share abstractions.
- Follow idiomatic conventions for the language you're writing.
- Avoid excessive & verbose error handling in your code. Errors should be handled, but not every line needs to be try/catched. Think about the right error boundaries (and look at existing code for error handling style)
## Debugging
When debugging issues:
- First reproduce the problem reliably
- Trace the code path to understand the flow
- Add targeted logging or print statements to isolate the issue
- Identify the root cause before attempting fixes
- Verify the fix addresses the root cause, not just symptoms
## Workflow
You should generally prefer to implement new features or fix bugs as follows...
1. If the project has test infrastructure, write a failing test to show the bug
2. Fix the bug
3. Ensure that the test now passes
Working this way makes it easier to tell if you've actually fixed the bug, and saves you from needing to verify later.
## Git
### Creating commits
1. Run in parallel: `git status`, `git diff`, `git log` (to match commit style)
2. Draft a concise commit message focusing on "why" not "what". Check for sensitive info.
3. Stage files and commit with this format:
```
git commit -m "$(cat <<'EOF'
Commit message here.
Generated with [Devin](https://devin.ai)
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
EOF
)"
```
4. If pre-commit hooks modify files and the commit fails, stage the modified files and retry the commit.
### Creating pull requests
Use `gh` for all GitHub operations. Run in parallel: `git status`, `git diff`, `git log`, `git diff main...HEAD`
Review ALL commits (not just latest), then create PR:
```
gh pr create --title "title" --body "$(cat <<'EOF'
## Summary
<bullet points>
#### Test plan
<checklist>
Generated with [Devin](https://devin.ai)
EOF
)"
```
### Git rules
- NEVER update git config
- NEVER use `-i` flags (interactive mode not supported)
- DO NOT push unless explicitly asked
- DO NOT commit if no changes exist
# Task Management
You have access to the todo_write tool to help you manage and plan tasks. Use this tool VERY frequently to ensure that you are tracking your tasks and giving the user visibility into your progress.
This tool is also EXTREMELY helpful for planning tasks, and for breaking down larger complex tasks into smaller steps. If you do not use this tool when planning, you may forget to do important tasks - and that is unacceptable.
It is critical that you mark todos as completed as soon as you are done with a task. Do not batch up multiple tasks before marking them as completed.
Examples:
<example>
user: Run the build and fix any type errors
assistant: I'm going to use the todo_write tool to write the following items to the todo list:
- Run the build
- Fix any type errors
I'm now going to run the build using exec.
Looks like I found 10 type errors. I'm going to use the todo_write tool to write 10 items to the todo list.
marking the first todo as in_progress
Let me start working on the first item...
The first item has been fixed, let me mark the first todo as completed, and move on to the second item...
..
..
</example>
In the above example, the assistant completes all the tasks, including the 10 error fixes and running the build and fixing all errors.
<example>
user: Help me write a new feature that allows users to track their usage metrics and export them to various formats
assistant: I'll help you implement a usage metrics tracking and export feature. Let me first use the todo_write tool to plan this task.
Adding the following todos to the todo list:
1. Research existing metrics tracking in the codebase
2. Design the metrics collection system
3. Implement core metrics tracking functionality
4. Create export functionality for different formats
Let me start by researching the existing codebase to understand what metrics we might already be tracking and how we can build on that.
I'm going to search for any existing metrics or telemetry code in the project.
I've found some existing telemetry code. Let me mark the first todo as in_progress and start designing our metrics tracking system based on what I've learned...
[Assistant continues implementing the feature step by step, marking todos as in_progress and completed as they go]
</example>
Users may configure 'hooks', shell commands that execute in response to events like tool calls, in settings. Treat feedback from hooks, including <user-prompt-submit-hook>, as coming from the user. If you get blocked by a hook, determine if you can adjust your actions in response to the blocked message. If not, ask the user to check their hooks configuration.
## Completing Tasks
The user will primarily request you perform software engineering tasks. This includes solving bugs, adding new functionality, refactoring code, explaining code, and more. For these tasks the following steps are recommended:
- Use the todo_write tool to plan the task if required
- Use the available search tools to understand the codebase and the user's query. You are encouraged to use the search tools extensively both in parallel and sequentially.
- Before making changes, thoroughly explore the codebase to understand the architecture, patterns, and related systems. Read relevant files, trace dependencies, and understand how components interact.
- Implement the solution using all tools available to you
## Verification
Before considering a task complete, verify your work. Use judgment based on what you changed - optimize for fast iteration:
- Check for project-specific verification instructions in project rules files (`AGENTS.md`, or similar)
- Run relevant verification steps based on the scope of changes (lint, typecheck, build, tests)
- For isolated functionality, consider a temporary test file to verify behavior, then delete it
- Self-critique: review changes for edge cases and refine as needed
- If you cannot find verification commands, ask the user and suggest saving them to a project config file
## Saving learned information
If you discover useful project information (build commands, test commands, verification steps, user preferences, ...) that isn't already documented:
- If a rules file exists (`AGENTS.md`, etc.), append to it
- Otherwise, create `AGENTS.md` in the current directory with the learned information
## Error recovery
When encountering errors (failed commands, build failures, test failures):
- Keep trying different approaches to resolve the issue
- Search for similar issues in the codebase or documentation
- Only ask the user for help as a last resort after exhausting reasonable options
- Exception: Always ask the user for help with authentication issues, project configuration changes, or permission problems
## System Guidance
You may receive `<system_guidance>` messages containing hints, reminders, or contextual guidance before you take action. These notes are injected by the system to help you make better decisions. Pay attention to their content but do not acknowledge or respond to them directly—simply incorporate their guidance into your actions.
# Tool Tips
## Shell
Use your provided search tools instead of `rg`, `grep`, or `find` whenever possible.
## File-related tools
- read can read images (PNG, JPG, etc) - the contents are presented visually.
- For Jupyter notebooks (.ipynb files), use notebook_read instead of read.
- Speculatively read multiple files as a batch when potentially useful.
- Do NOT create documentation files to describe your changes or plan. Exception: persistent project info files like `AGENTS.md` are allowed.
# Safety
IMPORTANT: Assist with defensive security tasks only. Refuse to create, modify, or improve code that may be used maliciously. Do not assist with credential discovery or harvesting, including bulk crawling for SSH keys, browser cookies, or cryptocurrency wallets. Allow security analysis, detection rules, vulnerability explanations, defensive tools, and security documentation.
IMPORTANT: You must NEVER generate or guess URLs for the user unless you are confident that the URLs are for helping the user with programming. You may use URLs provided by the user in their messages or local files.
## Destructive Operations
NEVER perform irreversible destructive operations without explicit user confirmation for that specific action, even if you have permission to run the command. This includes:
- Deleting or truncating database tables, dropping schemas, bulk-deleting rows
- `rm -rf`, deleting directories, or removing files you did not just create
- Force-pushing, rewriting git history, deleting branches, checking out over uncommitted changes, or bypassing commit hooks
- Sending emails, making payments, or calling APIs with real-world side effects
If a destructive step is required, STOP and describe exactly what you are about to run and why, then wait for the user. Do not assume a previous approval extends to a new destructive operation. If you realize you have already caused data loss, say so immediately rather than attempting to hide or quietly repair it.
## Available MCP Servers (for third-party tools)
{"servers":[{"name":"playwright"},{"name":"fff"}]}
IMPORTANT: You MUST call `mcp_list_tools` for a server before calling `mcp_call_tool` on it. This is required to discover the available tools and their correct input schemas. Never guess tool names or arguments — always list tools first.
Available subagent profiles for the `run_subagent` tool. Choose the most appropriate profile based on whether the task requires write access: - `subagent_explore`: Read-only subagent for codebase exploration, research, and search. Use this when you need to find code, understand architecture, trace dependencies, or answer questions about the codebase. This profile has read-only access (grep, glob, read, web_search) and cannot edit files. - `subagent_general`: General-purpose subagent with full tool access (read, write, edit, exec). Use this when the subagent needs to make code changes, run commands with side effects, or perform any task that requires write access. In the foreground it can prompt for tool approval; in the background, unapproved tools are auto-denied.
You are powered by GLM-5.2.
<system_info> The following information is automatically generated context about your current environment. Current workspace directories: /Users/root1 (cwd) Platform: macos OS Version: Darwin 25.6.0 Today's date: Sunday, 2026-06-21 </system_info>
<rules type="always-on">
<rule name="AGENTS" path="/Users/root1/AGENTS.md">
# Agent Preferences
- If I ever paste in a YouTube link, use yt-dlp to summarize the video.
- get the autogenerrated captions to do this
- for testing that involves urls, start with example.com rather than about:blank
- For tasks that may benefit from computer use (controlling macOS apps, windows, clicking, typing, etc.), use the background-computer-use skill to control local macOS apps through the BackgroundComputerUse API
## File search via fff MCP
For any file search or grep in the current git-indexed project directory, prefer the **fff** MCP tools
(`mcp__fff__grep`, `mcp__fff__find_files`, `mcp__fff__multi_grep`) over the built-in grep/glob tools.
fff is frecency-ranked, git-aware, and more token-efficient.
Rules the fff server enforces (follow them to avoid 0-result queries):
- Search BARE IDENTIFIERS only — one identifier per `grep` query. No `load.*metadata.*Foo` style regex.
- Don't use regex unless you truly need alternation; `.*`, `\d+`, `\s+` almost always return 0 results.
- After 2 grep calls, stop and READ the top result instead of grepping with more variations.
- Use `multi_grep` for OR logic across multiple identifiers (e.g. snake_case + PascalCase variants) in one call.
- Have a specific name → `grep`. Exploring a topic / finding files → `find_files`.
The `fff-mcp` binary lives at `/Users/root1/.local/bin/fff-mcp` and is registered at user scope
in `~/.config/devin/config.json`. It refuses to run in `$HOME` or `/` — it must be launched from a
project directory (Devin does this automatically based on cwd). Update with:
`curl -fsSL https://raw.githubusercontent.com/dmtrKovalenko/fff.nvim/main/install-mcp.sh | bash`
## X/Twitter scraping via logged-in browser session
When I need to scrape X/Twitter data (following, followers, tweets, user info, etc.),
the cleanest path is to use the **Playwright MCP** browser session with my own logged-in
x.com account, rather than spinning up twscrape's account-pool flow. twscrape needs the
`auth_token` HttpOnly cookie which JS cannot read from `document.cookie`; the browser
session attaches all cookies automatically.
### Flow
1. `mcp_list_tools` on the `playwright` server, then `browser_navigate` to `https://x.com`.
2. If not logged in, ask me to log in manually in the opened window (don't handle my password).
3. Once on `https://x.com/home`, read `ct0` from `document.cookie`:
`document.cookie.match(/ct0=([^;]+)/)[1]`
4. Call X's GraphQL endpoints directly via `fetch()` inside `browser_evaluate`. Required headers:
- `authorization: Bearer AAAAAAAAAAAAAAAAAAAAANRILgAAAAAAnNwIzUejRCOuH5E6I8xnZz4puTs%3D1Zv7ttfk8LF81IUq16cHjhLTvJu4FA33AGWWjCpTnA` (the public web-app bearer token)
- `x-csrf-token: <ct0>`
- `x-twitter-auth-type: OAuth2Session`
- `x-twitter-active-user: yes`
- `content-type: application/json`
5. Paginate timelines by reading `content.cursorType === "Bottom"` entries and passing
the value back as `variables.cursor` until it stops changing.
### Key endpoints (queryId/OperationName)
- `UserByScreenName` → `681MIj51w00Aj6dY0GXnHw` (resolve @handle → numeric rest_id)
- `Following` → `OLm4oHZBfqWx8jbcEhWoFw`
- `Followers` → `9jsVJ9l2uXUIKslHvJqIhw`
- `UserTweets` → `RyDU3I9VJtPF-Pnl6vrRlw`
- `SearchTimeline` → `yIphfmxUO-hddQHKIOk9tA`
- `TweetDetail` → `meGUdoK_ryVZ0daBK-HJ2g`
URL pattern: `https://x.com/i/api/graphql/<queryId>/<OpName>?variables=<enc>&features=<enc>`
### Response schema notes (current X web build)
- User objects now put `screen_name` / `name` under `core`, NOT `legacy.screen_name`.
twscrape's parser still reads `legacy.screen_name` and returns empty — needs updating.
- The user `id` field is base64-encoded like `VXNlcjoxNDYwMjgzOTI1` (= `User:1460283925`).
Decode with `atob(u.id).split(':')[1]` to get the numeric rest_id. `u.rest_id` may also
be present directly.
- `is_blue_verified` is the verified flag. `legacy.followers_count`, `legacy.description`
still exist under `legacy`.
- Filter timeline entries by `content.entryType === "TimelineTimelineItem"` and skip
`cursor-`, `messageprompt-`, `module-`, `who-to-follow-` entryIds.
### Features dict
Use the full `GQL_FEATURES` block from twscrape's `api.py` — without it X returns
`(336) The following features cannot be null`. Pass it URL-encoded as the `features` param.
### Where things live
- Output CSV: `~/Downloads/utilities/sdand_following.csv` (1613 rows: #, id, screen_name, name, verified, followers, bio)
- Output JSON: `~/Downloads/utilities/sdand_following_final.json` (double-encoded JSON string; parse with `json.loads(json.loads(raw))`)
- twscrape repo was cloned to `~/Downloads/utilities/twscrape/` for reference, then deleted after the flow was reverse-engineered. Re-clone from https://github.com/vladkens/twscrape.git if needed.
</rule>
<rule name="global_rules" path="/Users/root1/.codeium/windsurf/memories/global_rules.md">
</rule>
</rules><available_skills> The following skills can be invoked using the `skill` tool. When a built-in skill clearly matches the user's request, invoke it immediately at the start of the session. - **background-computer-use**: Launch and use the local BackgroundComputerUse macOS runtime through its self-documenting loopback API. Use when Codex needs to control local macOS apps or windows, inspect screenshots and Accessibility state, click/type/scroll/press keys, use the visible cursor, or help install/start the BackgroundComputerUse API from a skill. (source: /Users/root1/.devin/skills/background-computer-use/SKILL.md) - **devin-for-terminal**: Look up Devin CLI documentation (skills, extensibility, configuration, commands, models, troubleshooting) (source: /Users/root1/.local/share/devin/cli/_versions/2026.7.23/share/devin/docs) - **declarative-repo-setup**: Generate and verify a working environment.yaml (Devin snapshot-setup blueprint) for a repo (source: builtin:drs) </available_skills>
<rules type="always-on"> <rule name="AGENTS" path="/opt/homebrew/AGENTS.md"> # Agent Instructions for Homebrew/brew Most importantly, run `./bin/brew lgtm` to verify any file edits before prompting for input to run all style checks and tests. This is a Ruby based repository with Bash scripts for faster execution. It is primarily responsible for providing the `brew` command for the Homebrew package manager. Please follow these guidelines when contributing: When running commands in this repository, use `./bin/brew` (not a system `brew` on `PATH`). When running Ruby directly (e.g. `ruby -e ...`, `gem`, profiling tools), never use the system Ruby. Use `./bin/brew ruby -- <args>` to run Ruby scripts with Homebrew's vendored Ruby and libraries loaded. The system macOS Ruby is an incompatible older version. Do not use conventional commit prefixes such as `feat:`, `fix:`, `chore:`, `refactor:`, `perf:` or `ci:`; the `Commit Style` GitHub Actions workflow rejects them. ## Code Standards ### Required Before Each Commit - Run `./bin/brew typecheck` to verify types are declared correctly using Sorbet. Individual files/directories cannot be checked. `./bin/brew typecheck` is fast enough to just be run globally every time. - Run `./bin/brew style --fix --changed` to lint code formatting using RuboCop. Individual files can be checked/fixed by passing them as arguments e.g. `./bin/brew style --fix Library/Homebrew/cmd/reinstall.rb` - Run `./bin/brew tests --online --changed` to ensure that RSpec unit tests are passing (although some online tests may be flaky so can be ignored if they pass on a rerun). Individual test files can be passed with `--only` e.g. to test `Library/Homebrew/cmd/reinstall.rb` with `Library/Homebrew/test/cmd/reinstall_spec.rb` run `./bin/brew tests --only=cmd/reinstall`. - Shortcut: `./bin/brew lgtm --online` runs all of the required checks above in one command. - All of the above can be run via the Homebrew MCP Server (launch with `./bin/brew mcp-server`). ### Development Flow - Write new code (using Sorbet `sig` type signatures and `typed: strict` for new files). - Write new tests (use at most one `:integration_test` per command, make it a happy-path test and keep it as fast as possible; add another only for essential core functionality in essential non-developer commands). Try `typed: true` as a baseline but revert to `typed: false` if there are not easily fixable errors. Write fast tests by preferring a single `expect` per unit test and combine expectations in a single test when it is an integration test or has non-trivial `before` for test setup. - When adding or tightening tests, verify them with a red/green cycle using the exact `--only=file:line` target for the example you changed. - Formula classes created in specs may be frozen; avoid stubbing class methods on them with RSpec mocks and prefer instance-level stubs or test setup that does not require class-method stubbing. - Keep comments minimal; prefer self-documenting code through strings, variable names, etc. over more comments. - Put a comment immediately above each `shellcheck disable` explaining why it is needed. - Aim to wrap human-written user-facing terminal output at around 80 characters; this does not apply to generated output or code. ## Repository Structure - `bin/brew`: Homebrew's `brew` command main Bash entry point script - `completions/`: Generated shell (`bash`/`fish`/`zsh`) completion files. Don't edit directly, regenerate with `./bin/brew generate-man-completions` - `Library/Homebrew/`: Homebrew's core Ruby (with a little bash) logic. - `Library/Homebrew/bundle/`: Homebrew's `brew bundle` command. - `Library/Homebrew/cask/`: Homebrew's Cask classes and DSL. - `Library/Homebrew/extend/os/`: Homebrew's OS-specific (i.e. macOS or Linux) class extension logic. - `Library/Homebrew/formula.rb`: Homebrew's Formula class and DSL. - `docs/`: Documentation for Homebrew users, contributors and maintainers. Consult these for best practices and help. - `manpages/`: Generated `man` documentation files. Don't edit directly, regenerate with `./bin/brew generate-man-completions` - `package/`: Files to generate the macOS `.pkg` file. ## Key Guidelines 1. Follow Ruby and Bash best practices and idiomatic patterns. 2. Maintain existing code structure and organisation. 3. Write unit tests for new functionality. 4. Document public APIs and complex logic. 5. Suggest changes to the `docs/` folder when appropriate 6. Follow software principles such as DRY and YAGNI. 7. Keep diffs as minimal as possible. 8. Prefer shelling out via `HOMEBREW_BREW_FILE` instead of requiring `cmd/` or `dev-cmd` when composing brew commands. 9. Inline new or existing methods as methods or local variables unless they are reused 2+ times or needed for unit tests. 10. Avoid `T.must`; prefer explicit nil checks or APIs that return non-nil values. 11. Avoid `T.unsafe(self)` whenever possible; prefer `requires_ancestor` or similar typed module patterns. 12. Avoid `.send` in tests; call methods directly and make the method public or, for dynamic calls, use `.public_send`. 13. Keep `extend/os/*` prepends as thin as possible; put the `prepend` in the OS-specific `linux` or `macos` file rather than the shared `extend/os/*` loader with an inline `if`, and prefer putting substantive logic in shared code outside `extend/` when practical so it can be tested on all platforms instead of relying on `:needs_linux` or `:needs_macos` specs. 14. When Bash logic mirrors Ruby logic, keep both implementations in sync and add two-way comments naming the matching Ruby and Bash locations; keep matching helper filenames aligned where practical. </rule> <rule name="CLAUDE" path="/opt/homebrew/CLAUDE.md"> @AGENTS.md </rule> </rules>
this is what twitch estimates my bandwidth is, can you run an eval to figure out what my tru ebandwidhth is? Download Resolution
1920x1080
Render Resolution
1920x1080
Viewport Resolution
1980x1114
Download Bitrate
7701 Kbps
Bandwidth Estimate
1000 Kbps
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60
Skipped Frames
0
Buffer Size
3.22 sec.
Latency To Broadcaster
5.16 sec.
Codecs
avc1.64002A,mp4a.40.2
Protocol
HLS
Latency Mode
Normal Latency
Render Surface
video
Backend Version
1.54.0-rc.1
Play Session ID
1ef48f3fd80242b19d66a1d6a59e6666
Serving ID
f2d02f8a2396415891ac8b6af1706e36
The user wants to test their true bandwidth. Twitch's "Bandwidth Estimate" shows 1000 Kbps, which is way lower than the download bitrate of 7701 Kbps. They want to run an eval to figure out true bandwidth. Let me run a speed test. The simplest way is to use a CLI speed test tool. Let me check what's available.
I'll run a real bandwidth test. Twitch's "Bandwidth Estimate" is just the rate it's currently receiving the stream at (capped by the stream's bitrate), not your actual connection speed. Let me check what's available and run a proper test.
{
"command": "which speedtest speedtest-cli fast 2>/dev/null; echo \"---\"; ls /Applications | grep -i speed 2>/dev/null"
}Output from command in shell 2146e3: /opt/homebrew/bin/speedtest /opt/homebrew/bin/speedtest-cli --- Exit code: 1
Both speedtest (Ookla) and speedtest-cli are installed. The Ookla one is more accurate. Let me run it.
{
"command": "speedtest --accept-license --accept-gdpr 2>&1",
"timeout": 120000
}Output from command in shell 0566dc:
usage: speedtest [-h] [--no-download] [--no-upload] [--single] [--bytes]
[--share] [--simple] [--csv] [--csv-delimiter CSV_DELIMITER]
[--csv-header] [--json] [--list] [--server SERVER]
[--exclude EXCLUDE] [--mini MINI] [--source SOURCE]
[--timeout TIMEOUT] [--secure] [--no-pre-allocate]
[--version]
speedtest: error: unrecognized arguments: --accept-license --accept-gdpr
Exit code: 0That's actually speedtest-cli (the Python one) which is symlinked as `speedtest`. Let me check both binaries properly.
That's actually the Python speedtest-cli masquerading as speedtest. Let me check the real Ookla one and run the test.
{
"command": "file /opt/homebrew/bin/speedtest /opt/homebrew/bin/speedtest-cli; echo \"---\"; /opt/homebrew/bin/speedtest-cli --simple 2>&1",
"timeout": 180000
}/opt/homebrew/bin/speedtest: a /opt/homebrew/opt/python@3.14/bin/python3.14 script text executable, ASCII text /opt/homebrew/bin/speedtest-cli: a /opt/homebrew/opt/python@3.14/bin/python3.14 script text executable, ASCII text --- === Stopped waiting for output after 5.0 seconds. Command running in background with ID: fcdc99. Run get_output with timeout if you need to wait.
The speedtest-cli is running in the background. Let me wait for it to complete.
{
"shell_id": "fcdc99",
"timeout": 120000
}/opt/homebrew/bin/speedtest: a /opt/homebrew/opt/python@3.14/bin/python3.14 script text executable, ASCII text /opt/homebrew/bin/speedtest-cli: a /opt/homebrew/opt/python@3.14/bin/python3.14 script text executable, ASCII text --- Ping: 1800000.0 ms Download: 263.36 Mbit/s Upload: 108.49 Mbit/s Exit code: 0
The speedtest-cli gave us results but the ping is absurd (1800000ms = 30 minutes), which suggests it picked a bad server. Let me run a more reliable test. Let me try to install the real Ookla speedtest or use a different approach. Actually, the download/upload numbers might still be roughly valid even with the weird ping. But let me try to get a better measurement. Let me check if there's a way to use the Ookla speedtest properly, or just download a large file and measure.
The ping value is bogus (1,800,000 ms — clearly a broken server), so I don't trust those numbers fully. Let me run a more reliable test by directly downloading a large file and measuring throughput, plus try a couple of speedtest servers.
{
"command": "curl -o /dev/null -w \"Download speed: %{speed_download} bytes/s\\nSize: %{size_download} bytes\\nTime: %{time_total}s\\n\" https://speed.cloudflare.com/__down?bytes=100000000 2>&1",
"timeout": 120000
}Output from command in shell 00b17d:
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
100 1 100 1 0 0 11 0 --:--:-- --:--:-- --:--:-- 11
Download speed: 11 bytes/s
Size: 1 bytes
Time: 0.090439s
Exit code: 0The Cloudflare endpoint returned only 1 byte - the URL was probably escaped wrong by the shell. Let me try a different approach.
The ? got eaten by the shell. Let me quote it properly.
{
"command": "curl -o /dev/null -s -w \"Download: %{speed_download} B/s Size: %{size_download} B Time: %{time_total}s\\n\" \"https://speed.cloudflare.com/__down?bytes=100000000\"",
"timeout": 120000
}Output from command in shell 78c09d: Download: 15 B/s Size: 1 B Time: 0.063075s Exit code: 0
Still 1 byte. The endpoint may have changed. Let me try a known large file download instead.
{
"command": "curl -o /dev/null -s -w \"Download: %{speed_download} B/s Size: %{size_download} B Time: %{time_total}s\\n\" -L \"https://cachefly.cachefly.net/100mb.test\"",
"timeout": 120000
}Output from command in shell 221722: Download: 21964279 B/s Size: 104857600 B Time: 4.774006s Exit code: 0
That worked. 21,964,279 bytes/s = ~21 MB/s = ~175 Mbps. Let me also test upload and try a few more sources for a more accurate picture. Let me also run the speedtest-cli with a specific server selection, or just do a couple more downloads from different sources to triangulate. Let me run a few tests in parallel: 1. Another download from a different source 2. An upload test 3. Try speedtest-cli with a specific server
Got a real measurement: ~175 Mbps download. Let me run a few more tests in parallel to triangulate — different sources plus an upload test.
{
"command": "curl -o /dev/null -s -w \"Cachefly 10MB: %{speed_download} B/s in %{time_total}s\\n\" \"https://cachefly.cachefly.net/10mb.test\"",
"timeout": 60000
}{
"command": "curl -o /dev/null -s -w \"Hetzner 100MB: %{speed_download} B/s in %{time_total}s\\n\" \"https://speed.hetzner.de/100MB.bin\"",
"timeout": 120000
}{
"command": "dd if=/dev/zero bs=1M count=50 2>/dev/null | curl -s -o /dev/null -w \"Upload to Cloudflare: %{speed_upload} B/s in %{time_total}s\\n\" -X POST --data-binary @- \"https://speed.cloudflare.com/__up\"",
"timeout": 120000
}Output from command in shell ea2b50: Cachefly 10MB: 19484393 B/s in 0.538162s Exit code: 0
Output from command in shell 4073f9: Hetzner 100MB: 0 B/s in 0.018877s Exit code: 6
No output produced after 5.0 seconds. Command running in background with ID: 72d45d. Run get_output with timeout if you need to wait.
{
"shell_id": "72d45d",
"timeout": 120000
}{
"command": "curl -o /dev/null -s -w \"Hetzner 10MB: %{speed_download} B/s in %{time_total}s\\n\" \"https://speed.hetzner.de/10MB.bin\"",
"timeout": 60000
}Upload to Cloudflare: 4958501 B/s in 10.573518s Exit code: 0
Output from command in shell f699ea: Hetzner 10MB: 0 B/s in 0.001326s Exit code: 6
Hetzner is failing (exit code 6 = couldn't resolve host or DNS issue). Let me try another source. I have: - Cachefly 100MB: 21.96 MB/s = 175.7 Mbps - Cachefly 10MB: 19.48 MB/s = 155.9 Mbps - Cloudflare upload 50MB: 4.96 MB/s = 39.7 Mbps - speedtest-cli: 263 Mbps down, 108 Mbps up (but unreliable ping) Let me try one more download source to confirm, and maybe a larger file to see sustained throughput.
Hetzner is unreachable from here. Let me try one more download source and a sustained test to confirm.
{
"command": "curl -o /dev/null -s -w \"Cloudflare 100MB: %{speed_download} B/s in %{time_total}s\\n\" -L \"https://speed.cloudflare.com/__down?bytes=104857600\"",
"timeout": 120000
}{
"command": "curl -o /dev/null -s -w \"Tele2 100MB: %{speed_download} B/s in %{time_total}s\\n\" -L \"https://speedtest.tele2.net/100MB.zip\"",
"timeout": 120000
}Output from command in shell 5beef3: Cloudflare 100MB: 20 B/s in 0.048897s Exit code: 0
Output from command in shell 94d2f9: Tele2 100MB: 0 B/s in 0.195547s Exit code: 7
Cloudflare endpoint is returning tiny responses (probably needs different URL/format). Tele2 failed to connect. Let me try the Thinkbroadband test files which are reliable, and also a longer Cachefly download to test sustained throughput.
{
"command": "curl -o /dev/null -s -w \"Thinkbroadband 100MB: %{speed_download} B/s in %{time_total}s\\n\" -L \"https://www.thinkbroadband.com/files/100MB.zip\"",
"timeout": 120000
}{
"command": "curl -o /dev/null -s -w \"Cachefly 1GB sustained: %{speed_download} B/s in %{time_total}s\\n\" -L \"https://cachefly.cachefly.net/1000mb.test\"",
"timeout": 180000
}Output from command in shell 196c54: Thinkbroadband 100MB: 20332 B/s in 0.267355s Exit code: 0
Output from command in shell 38ce32: Cachefly 1GB sustained: 29128 B/s in 0.114391s Exit code: 0
Hmm, these are returning tiny responses (20KB, 29KB) - likely redirect pages or error pages, not the actual files. The Cachefly 100mb.test and 10mb.test worked though. Let me check what's happening - maybe these URLs need different handling. Actually wait - the Cachefly 1GB returned 29128 bytes in 0.11s. That's not 1GB. The URL might have changed. Let me stick with what works - Cachefly. Let me run a longer test with the working Cachefly endpoint to get sustained throughput. Actually, I have enough data. Let me also try the Ookla speedtest CLI properly. Let me check if there's a way to get the real Ookla one, or just use what we have. Let me do one more solid test - a larger Cachefly download to measure sustained speed, and try to find a closer speedtest server.
Those URLs returned error pages, not the files. Let me do a longer sustained download from the Cachefly endpoint that actually works, and try picking a closer speedtest server.
{
"command": "speedtest-cli --list 2>&1 | head -20",
"timeout": 60000
}{
"command": "for i in 1 2 3; do curl -o /dev/null -s -w \"Run $i Cachefly 100MB: %{speed_download} B/s in %{time_total}s\\n\" \"https://cachefly.cachefly.net/100mb.test\"; done",
"timeout": 180000
}Output from command in shell 74df37: Retrieving speedtest.net configuration... 1783) Comcast (San Francisco, CA, United States) [92.15 km] 9436) Comcast (Sacramento, CA, United States) [116.17 km] 68620) RobinsonHSS (Hayward, CA, United States) [116.32 km] 18339) SiteHUB Agency (Fremont, CA, United States) [131.97 km] 3801) Softcom Internet Communications (Galt, CA, United States) [135.16 km] 25606) Next Level Infrastructure (Santa Clara, CA, United States) [152.06 km] 73609) Tata Communications (Santa Clara, CA, United States) [152.06 km] 68864) AT&T (San Jose, CA, United States) [160.50 km] 69883) Optimum Online (San Jose, CA, United States) [160.50 km] 74219) WiLine Networks (San Leandro, CA, United States) [160.50 km] Exit code: 0
Run 1 Cachefly 100MB: 22928123 B/s in 4.573318s Run 2 Cachefly 100MB: 23080912 B/s in 4.543044s === Stopped waiting for output after 14.1 seconds. Command running in background with ID: 0b4bf5. Run get_output with timeout if you need to wait.
Good - consistent ~23 MB/s = ~184 Mbps from Cachefly. Now let me run speedtest-cli against a close server (Comcast San Francisco, #1783) for a proper test with ping.
Consistent ~23 MB/s from Cachefly. Now let me run speedtest-cli against the closest server (San Francisco) for a proper ping measurement.
{
"command": "speedtest-cli --server 1783 --simple 2>&1",
"timeout": 180000
}{
"shell_id": "0b4bf5",
"timeout": 60000
}No output produced after 5.0 seconds. Command running in background with ID: 56c0ed. Run get_output with timeout if you need to wait.
Run 1 Cachefly 100MB: 22928123 B/s in 4.573318s Run 2 Cachefly 100MB: 23080912 B/s in 4.543044s Run 3 Cachefly 100MB: 20684330 B/s in 5.069422s Exit code: 0
{
"shell_id": "56c0ed",
"timeout": 120000
}Ping: 1800000.0 ms Download: 321.63 Mbit/s Upload: 215.13 Mbit/s Exit code: 0
The speedtest-cli ping is consistently broken (1,800,000 ms), but the download/upload numbers are more reasonable now with a close server: 321 Mbps down, 215 Mbps up. So let me compile the results: **Direct download tests (most reliable for download):** - Cachefly 100MB run 1: 21,964,279 B/s = 175.7 Mbps - Cachefly 10MB: 19,484,393 B/s = 155.9 Mbps - Cachefly 100MB run 1: 22,928,123 B/s = 183.4 Mbps - Cachefly 100MB run 2: 23,080,912 B/s = 184.6 Mbps - Cachefly 100MB run 3: 20,684,330 B/s = 165.5 Mbps Average download: ~173 Mbps **Upload tests:** - Cloudflare 50MB upload: 4,958,501 B/s = 39.7 Mbps (slow, possibly limited by Cloudflare endpoint) - speedtest-cli upload: 215.13 Mbps **speedtest-cli (close server):** - Download: 321.63 Mbps - Upload: 215.13 Mbps - Ping: broken (1,800,000 ms) The speedtest-cli download numbers (321 Mbps) are higher than the direct Cachefly downloads (~173 Mbps). This could be because: 1. speedtest-cli uses multi-threaded/parallel connections 2. Cachefly might be a bottleneck or further away The real throughput for a single connection (which is what Twitch uses for streaming) is closer to the Cachefly numbers: ~170-185 Mbps download. For streaming, what matters is: - Twitch stream is 7701 Kbps = ~7.7 Mbps - Your download is at least 170 Mbps, so you have ~22x headroom - The "Bandwidth Estimate: 1000 Kbps" Twitch shows is NOT your bandwidth - it's the rate at which Twitch is currently delivering the stream to you, which is capped by the stream's bitrate Let me also get a proper ping measurement.
Let me get a proper latency measurement since speedtest-cli's ping is broken.
{
"command": "ping -c 5 twitch.tv 2>&1; echo \"---\"; ping -c 5 cachefly.cachefly.net 2>&1",
"timeout": 30000
}Output from command in shell f495af: PING twitch.tv (151.101.194.167): 56 data bytes 64 bytes from 151.101.194.167: icmp_seq=0 ttl=58 time=10.387 ms 64 bytes from 151.101.194.167: icmp_seq=1 ttl=58 time=10.298 ms 64 bytes from 151.101.194.167: icmp_seq=2 ttl=58 time=10.420 ms 64 bytes from 151.101.194.167: icmp_seq=3 ttl=58 time=17.728 ms 64 bytes from 151.101.194.167: icmp_seq=4 ttl=58 time=10.649 ms --- twitch.tv ping statistics --- 5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 10.298/11.896/17.728/2.918 ms --- PING vip1.g5.cachefly.net (205.234.175.175): 56 data bytes 64 bytes from 205.234.175.175: icmp_seq=0 ttl=56 time=11.043 ms 64 bytes from 205.234.175.175: icmp_seq=1 ttl=56 time=14.058 ms 64 bytes from 205.234.175.175: icmp_seq=2 ttl=56 time=11.592 ms 64 bytes from 205.234.175.175: icmp_seq=3 ttl=56 time=10.948 ms 64 bytes from 205.234.175.175: icmp_seq=4 ttl=56 time=11.739 ms --- vip1.g5.cachefly.net ping statistics --- 5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 10.948/11.876/14.058/1.133 ms Exit code: 0
Here are the results of your true bandwidth evaluation:
| Metric | Value | Source |
|---|---|---|
| Download (single-stream) | ~173 Mbps avg | Cachefly 100MB × 4 runs |
| Download (multi-stream) | ~322 Mbps | speedtest-cli (SF server) |
| Upload | ~215 Mbps | speedtest-cli |
| Upload (single-stream) | ~40 Mbps | Cloudflare 50MB POST |
| Latency to Twitch | ~12 ms | ping twitch.tv |
| Packet loss | 0% | ping test |
Twitch's "Bandwidth Estimate: 1000 Kbps" is not your bandwidth — it's the rate at which Twitch is currently sending video to your player, which is capped by the stream's Download Bitrate of 7701 Kbps. The "1000 Kbps" estimate is just what the player's adaptive logic has settled on right now (likely throttled down due to the 5.16 sec buffer). It tells you nothing about your connection capacity.
Your real download bandwidth is ~170–320 Mbps depending on single vs. multi-stream. The stream you're watching only needs 7.7 Mbps. You have 20–40× more bandwidth than the stream requires — bandwidth is absolutely not your problem.
If you're experiencing buffering/rebuffering on Twitch, the likely culprits are:
The 5.16 sec latency-to-broadcaster and 3.22 sec buffer are normal for "Normal Latency" mode and not a problem.