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 commands/gregorbiswanger/featherspec/sdd-setupgit clone --depth 1 https://github.com/GregorBiswanger/featherspecWhat 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 | $0.00024 | $0.02902 |
| Opus 5 | $0.00012 | $0.01451 |
| Sonnet 5 | $0.00005 | $0.00580 |
| Haiku 4.5 | $0.00002 | $0.00290 |
Grade A, and why
sdd-setup 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 — 200 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/sdd-setup — SDD Setup Wizard
The user may name a documentation language, project name, or stack after the command. If any are missing, ask for them in the wizard below.
You are running an onboarding wizard for this repository.
Session opening — language first, then orientation
Open under a 🪶 **FeatherSpec** banner with at most two short English sentences — a
warm one-line welcome to the template and that setup starts with one question — then
immediately ask Step 0 (the language question). Everything before the language is
chosen stays English and minimal: no SDD explanation, no command table yet.
A mixed-language opening is exactly what this ordering prevents. A re-run is a repository a
previous setup already touched — the Memory Bank carries real content instead of TBD
placeholders, or the snapshot has been reconciled at least once — or a run where the language
arrived as an argument. Only then open in that language, confirm it in one line instead of
re-asking Step 0, and compress the orientation to one sentence: a re-run tunes, it does not
re-onboard. The DocLanguage: value the template ships with is a default nobody chose, so it
never makes a run a re-run: a first setup asks Step 0 even though AGENTS.md carries a value.
After DocLanguage is set, give the whole orientation in DocLanguage:
- Explain Spec-Driven Development in 3–5 plain sentences, rendering this definition
faithfully in
DocLanguage(translate it — do not quote English into a non-English session): Spec-Driven Development (SDD) is an AI-assisted development approach where a clear, structured, versioned specification is the primary artifact. Implementation and tests are derived from the spec and continuously validated against it (generate → verify → refine). Because agents generate code anchored to an explicit spec — and their output can be checked, corrected and regenerated against it — SDD yields higher-quality, more maintainable code than unstructured "vibe" prompting. The spec survives the implementation and stays the reference point for change. - State this repo's operating protocol as
AGENTS.mddefines it at the top — the three-step form is load-bearing, so render the three steps inDocLanguagewithout adding or merging steps. - Show the
/sdd-*commands from the Commands table inAGENTS.md— all of them, inDocLanguage. That table is the single machine-facing roster; keep no second copy here. Name the usual order in one line, rendered from the Flow line under Commands.
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 · 200 lines · 24 tokens per session scan A 67643a6ece44
sdd-setup is a command published in the GitHub repository GregorBiswanger/featherspec (44 stars, last pushed 3d ago), licensed MIT. It adds 24 tokens to every session and 2,902 once invoked, about $0.0001 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.
Other commands, from other repositories
spec-kitty-standalone
This host should read Spec Kitty's canonical standalone-invocation skill pack at.
spec-kitty.analyze
Spec-Driven Development for serious software developers. Spec Coding with with Claude, Cursor, Gemini, Codex. Kanban dashboard, git worktrees, auto-merge and more.
my-own-prompt
Spec-Driven Development for serious software developers. Spec Coding with with Claude, Cursor, Gemini, Codex. Kanban dashboard, git worktrees, auto-merge and more.
plan
Run /plan — see .claude/commands/plan.md for the authoritative spec.
speckit.assess.decide
Command "speckit.assess.decide" from github/spec-kit-copilot, covering when to run it, how to ask — always use the askuser tool, after the answers and what to ask about at the decide stage.
speckit.assess.define
Command "speckit.assess.define" from github/spec-kit-copilot, covering when to run it, how to ask — always use the askuser tool, after the answers and what to ask about at the define stage.