spec-plan

An interview-based planning command that turns a feature description into a structured specification and a readable specification document. It can also compile that specification into a PRD, a document listing the product requirements and stories.

In plain words
What is it for?
Use it to answer planning questions, create spec files, optionally generate a PRD, and choose the interview depth or test-driven development (TDD) setting.
Why use it?
It helps turn an incomplete idea into clearer requirements before implementation begins.

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/taoidle/plan-cascade/spec-plan
Clone the repo
git clone --depth 1 https://github.com/Taoidle/plan-cascade
Per session 99 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 561 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 $0.00099 $0.00561
Opus 5 $0.00049 $0.00280
Sonnet 5 $0.00020 $0.00112
Haiku 4.5 $0.00010 $0.00056

Measured 2d ago against content hash 61506c734cb8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec-plan 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.

commands/spec-plan.md · 61 lines

What it actually says

Plan Cascade - Spec Plan (Interview)

Start (or resume) a Specification Interview and generate:

  • spec.json (structured spec)
  • spec.md (human-readable spec)
  • .state/spec-interview.json (resume state)

Optionally compile spec.jsonprd.json.

Step 1: Parse Arguments

Parse:

  • <desc>: required description
  • --output-dir <dir>: optional (default: current directory)
  • --flow <quick|standard|full>: optional (default: standard)
  • --first-principles: optional
  • --max-questions N: optional (default: 18)
  • --feature-slug <slug>: optional (useful for Mega features)
  • --compile: optional (also run compile after interview)
  • --tdd <off|on|auto>: optional (only used with --compile)
  • --confirm / --no-confirm: optional (only used with --compile, --no-confirm wins)

Step 2: Run Interview (CLI)

Run:

uv run --project "${CLAUDE_PLUGIN_ROOT}" plan-cascade spec plan "<desc>" \
  --output-dir "<output-dir>" \
  --flow <flow> \
  --mode on \
  --max-questions <N> \
  --feature-slug "<slug>" \
  $( [ "<first-principles>" = true ] && echo "--first-principles" )

Step 3 (Optional): Compile to PRD

If --compile:

uv run --project "${CLAUDE_PLUGIN_ROOT}" plan-cascade spec compile \
  --output-dir "<output-dir>" \
  --flow <flow> \
  --tdd <tdd> \
  $( [ "<no-confirm>" = true ] && echo "--no-confirm" || true ) \
  $( [ "<confirm>" = true ] && echo "--confirm" || true )

Output Files

  • spec.json
  • spec.md
  • .state/spec-interview.json
  • prd.json (if --compile)
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. 2d ago First seen · 61 lines · 99 tokens per session scan A 61506c734cb8

Subscribe to this mod's changes

spec-plan is a command published in the GitHub repository Taoidle/plan-cascade (131 stars, last pushed 5mo ago), licensed MIT. It adds 99 tokens to every session and 561 once invoked, about $0.0005 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.