spec-auto

An unattended software-design command for preparing a feature after the product requirements and project decisions are already settled. SDD means specification-driven development: defining the design and rules before implementation.

In plain words
What is it for?
Use it to initialize the design framework or design one specific feature, provided the required product records, specifications, and foundation decision exist.
Why use it?
It avoids stopping for routine questions during an automated run, while requiring authoritative decisions and complete prerequisites before handing work to implementation.

Command

Install

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.

agentmods
npx agentmods add commands/nicelight/devrails-26/spec-auto
Clone the repo
git clone --depth 1 https://github.com/nicelight/DevRails-26
Per session 14 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,374 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00014 $0.01374
Opus 5 $0.00007 $0.00687
Sonnet 5 $0.00003 $0.00275
Haiku 4.5 $0.00001 $0.00137

Measured 3d ago against content hash f1b1d790fe80, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec-auto 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 3d 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.

skills/_shared/references/commands/spec-auto.md · 149 lines

How it starts

The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/spec-auto - Autonomous SDD design

Supported arguments:

  • --init;
  • exactly one FT-<NNN>.

<input_contract> --init requires the normal /spec-init inputs after /write-prd and before /prd-to-features.

FT-<NNN> requires:

  • clarified PRD, product, requirements, epics, and product features;
  • .memory-bank/spec-backbone.md and pure .memory-bank/spec-index.md;
  • a Global Backbone Status of complete, or valid minimal with explicit not_applicable rationale, plus positive integer Planning Revision; if missing or invalid, route to /spec-design;
  • .memory-bank/foundation.md with an explicit decision and, when foundation work is required, a closed Foundation Gate before product task handoff;
  • relevant canonical specs and accepted operator decisions;
  • .memory-bank/workflows/sdd-design-contract.md.

If no argument is given, infer --init only when clearly before /prd-to-features; otherwise halt and request one explicit product feature. Reject FT-000 and every multi-feature target. </input_contract>

<hard_invariants>

  • /spec-auto does not ask the operator during the unattended run and never treats that as permission to choose for them.
  • --init inherits /spec-init source authority and decision boundaries; it does not invent contracts, architecture, security, migration, irreversible data behavior, or Foundation sufficiency.
  • Apply the shared SDD authority and operator-decision contract in FT-<NNN> mode; unresolved material choices block instead of receiving agent defaults.
  • In post-PRD modes, inherit the accepted global architecture and material module/slice map. Do not reopen, weaken, or replace them with a framework recommendation, feature-local heuristic, or one-slice-per-feature mapping.
  • Preserve feature status vocabulary spec_design_status: complete|not_required|blocked.
  • Do not create a new status or terminal-state model.
  • /spec-auto preserves Global Backbone Planning Revision. Accepted backbone changes route to /spec-redesign; feature design never owns revision.
  • Current-state drift or baseline correction alone does not change Planning Revision while the accepted target remains unchanged. </hard_invariants>

<operator_decisions> Apply the shared operator-decision boundary. When it leaves a relevant material branch unresolved:

  • write the exact question, alternatives/impact, affected artifacts/features, and decision owner to the existing backbone, feature, spec, or autonomous decision log as appropriate;
  • set Pre-PRD Spec Status: blocked, Global Backbone Status blocked, or feature spec_design_status: blocked according to ownership;
  • stop with existing HALT_BLOCKING_QUESTIONS or HALT_CLARIFICATION_REQUIRED;
  • report the interactive resume skill (/write-prd, /spec-init, /feature-doctor, /spec-design, or /spec-redesign).

Non-decision implementation detail remains agent discretion. </operator_decisions>

<required_outputs>

Across modes, edit canonical artifacts only when durable framing/design state, routes, decisions, blockers, registry links, or applicable contracts have changed, or the existing contract needs repair. Do not append per-run audit/reconciliation history or mirror the final chat handoff.

Read the full file on GitHub · 149 lines

Changes

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.

  1. 3d ago First seen · 149 lines · 14 tokens per session scan A f1b1d790fe80

Subscribe to this mod's changes

spec-auto is a command published in the GitHub repository nicelight/DevRails-26 (22 stars, last pushed 5d ago), licensed MIT. It adds 14 tokens to every session and 1,374 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.