DeerFlow is an open-source super-agent harness that coordinates sub-agents, memory, tools, sandboxes, and extensible skills to handle research, coding, and content-creation tasks that may run for minutes or hours. It is intended for long-running, multi-step work performed by AI agents. The catalogue entries are skills, agents, and instructions that support its workflows.
Borrowing it
Nothing to install: this file belongs to bytedance/deer-flow. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/bytedance/deer-flow/main/.agent/skills/engineer-system-change/SKILL.mdgit clone --depth 1 https://github.com/bytedance/deer-flowWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/bytedance/deer-flow/engineer-system-change)<a href="https://agentmods.dev/skills/bytedance/deer-flow/engineer-system-change"><img src="https://agentmods.dev/badge/skills/bytedance/deer-flow/engineer-system-change.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00125 | $0.01886 |
| Opus 5 | $0.00063 | $0.00943 |
| Sonnet 5 | $0.00025 | $0.00377 |
| Haiku 4.5 | $0.00013 | $0.00189 |
Grade A, and why
engineer-system-change scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Engineer System Change
Treat every proposed change as a hypothesis about a real system, not as an implementation checklist. Establish whether the change should exist before designing or building it, then keep the solution and the process proportional to the risk.
Preserve the Task Boundary
- If asked only to assess, review, or plan, make no project or external-state changes.
- If explicitly asked to implement, including after an assessment, pass the decision gates before editing and verify the result afterward.
- Treat implementation permission as separate from permission to commit, push, deploy, publish, or update issues and pull requests.
- If repository truth matters, inspect the current target revision and relevant discussion. Do not rely on a stale checkout, an RFC alone, or remembered architecture.
- Separate verified facts, inferences, and unknowns. Do not turn missing evidence into a confident conclusion.
Apply the Decision Gates
1. Ground the Problem
- Trace the current user workflow, failure, or code path before proposing a solution.
- State the undesirable observable behavior and the invariant or outcome that should replace it.
- Identify who is affected and which concrete decision or action changes.
- Check whether the existing system, configuration, documentation, or operating procedure already solves the problem.
- Enumerate adjacent product paths and workarounds, not only the proposed target surface. Explain precisely which accepted outcome each alternative fails; do not claim “the only option” from one missing UI control or code path.
- Treat an absent field, interface, abstraction, or standard as an observation, not proof of a requirement.
Return STOP only when evidence affirmatively shows that no change is needed or the affected workflow already achieves the outcome. Return NEEDS_EVIDENCE when an unverified fact prevents the decision.
2. Name Semantic Consumers
For every proposed durable field, event, API, table, store, module, service, or workflow, establish:
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 6d ago First seen · 135 lines · 125 tokens per session scan A 3824ac0af277
engineer-system-change is a skill published in the GitHub repository bytedance/deer-flow (81,437 stars, last pushed today), licensed MIT. It adds 125 tokens to every session and 1,886 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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