Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/leejuoh/claude-code-zero/ducknpx skills add LeeJuOh/claude-code-zero --skill duckgit clone --depth 1 https://github.com/LeeJuOh/claude-code-zeroWhat 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 | $0.00074 | $0.00797 |
| Opus 5 | $0.00037 | $0.00398 |
| Sonnet 5 | $0.00015 | $0.00159 |
| Haiku 4.5 | $0.00007 | $0.00080 |
Grade A, and why
duck 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 2d 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 — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Duck (auto-detect)
Auto-detects which mode fits the user's current state and routes to the matching mode skill. Read ../ducking/engine.md for shared persona, principles, and session-management rules — they apply to every mode.
Mode Map
| Trigger phrase / state | Mode skill |
|---|---|
| "build this for me" / stated implementation intent, no plan or code yet | /duck-prebuild |
Active plan in conversation (or .claude/orientation.md-adjacent design doc) |
/duck-prebuild |
| Files recently created/modified in this session | /duck-verify |
Uncommitted changes (git diff --stat non-empty) |
/duck-review |
| User new to the repo, returning after long break, "where should I even start" | /duck-orient |
| None of the above | Ask the user which phase they want |
Detection Order
Check in this order — first match wins:
- Pre-coding intent — user just stated they want to build X but no plan/diff/code exists yet →
/duck-prebuild - Plan in context — a plan or design doc was produced in this session →
/duck-prebuild - Uncommitted changes —
git diff --statshows a real diff →/duck-review - Recent in-session edits — files were created or modified earlier in this session but not yet committed →
/duck-verify - Orientation gap — user appears unfamiliar with the repo →
/duck-orient - Ambiguous — ask the user which phase they want before continuing
Behavior When the User Picks Their Own Mode
If the user named a mode (prebuild, verify, review, orient — or the older design/plan words, both alias to prebuild), suggest the matching /duck-<mode> command and stop — don't run the mode flow inline. The dedicated mode skill carries the full instructions for that flow.
If the user passed $ARGUMENTS and it matches a known mode word, hand off to /duck-<mode> (map design/plan → prebuild; otherwise use $ARGUMENTS as-is):
"🦆 Quack — you want
/duck-<mode>. Call it directly instead."
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.
- 2d ago First seen · 51 lines · 74 tokens per session scan A 81616ce09dea
duck is a skill published in the GitHub repository LeeJuOh/claude-code-zero (51 stars, last pushed 3d ago), licensed MIT. It adds 74 tokens to every session and 797 once invoked, about $0.0004 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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