gsd-plan-phase

gsd-plan-phase is a skill for Claude Code from open-gsd/gsd-core. It costs 16 tokens per session (1,215 once invoked), scanned A, original, MIT.

A workflow that researches a project phase, creates a detailed PLAN.md file, and checks the plan before presenting it.

In plain words
What is it for?
Use it to research a phase, create its plan, inspect existing research, or refresh research before planning.
Why use it?
It turns a phase goal into an examined and verified implementation plan, reducing the chance of starting with unclear or incomplete steps.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths; names the AskUserQuestion tool.

Part of the gsd-core plugin — 72 skills, 35 agents, 7 hooks shipped together

Good fit Use it to research a phase, create its plan, inspect existing research, or refresh research before planning.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/open-gsd/gsd-core/gsd-plan-phase
About the project

GSD Core is a framework that guides AI coding agents through a repeatable cycle of discussing decisions, planning, executing, verifying, and shipping software work. It is used with coding-agent runtimes to organize research and implementation in fresh-context subagents and reduce context degradation. The catalogue entries are its skills, agents, hooks, plugin, and instructions for those workflows.

open-gsd/gsd-core · 9,319 stars · on GitHub · opengsd.net

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.

Any agent
npx skills add open-gsd/gsd-core --skill gsd-plan-phase
Clone the repo
git clone --depth 1 https://github.com/open-gsd/gsd-core

Made for: Claude Code.

Or install gsd-core, the plugin that ships this one along with the rest of its 72 skills, 35 agents, 7 hooks.

Wrote 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.

agentmods badge for gsd-plan-phase

README.md
[![agentmods](https://agentmods.dev/badge/skills/open-gsd/gsd-core/gsd-plan-phase/github.svg)](https://agentmods.dev/skills/open-gsd/gsd-core/gsd-plan-phase)
Your own site
<a href="https://agentmods.dev/skills/open-gsd/gsd-core/gsd-plan-phase"><img src="https://agentmods.dev/badge/skills/open-gsd/gsd-core/gsd-plan-phase/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for gsd-plan-phase

Your own site · 80×15
<a href="https://agentmods.dev/skills/open-gsd/gsd-core/gsd-plan-phase"><img src="https://agentmods.dev/badge/skills/open-gsd/gsd-core/gsd-plan-phase.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 16 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,215 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Rogue Agent · line 7
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
  • medium Excessive Agency · line 48
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 5.1 $0.00016 $0.01215
Opus 5 $0.00008 $0.00607
Sonnet 5 $0.00003 $0.00243
Haiku 4.5 $0.00002 $0.00121

Measured 7d ago against content hash 4ae27cbd263d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

gsd-plan-phase 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 7d 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/gsd-plan-phase/SKILL.md · 65 lines

How it starts

The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Default flow: Research (if needed) → Plan → Verify → Done

Research-only mode (--research-phase <N>): Spawn gsd-phase-researcher for phase N, write RESEARCH.md, then exit before the planner runs. Useful for cross-phase research, doc review before committing to a planning approach, and correction-without-replanning loops where iterating on research alone is dramatically cheaper than re-spawning the planner. Replaces the deleted research-phase command (#3042).

Research-only modifiers:

  • No flag — when RESEARCH.md already exists, auto-uses it: emits a one-line notice and exits cleanly, no prompt.
  • --research — force-refresh: re-spawn the researcher unconditionally, no prompt. Bypasses the existing-RESEARCH.md auto-use path.
  • --view — view-only: print existing RESEARCH.md to stdout. Does not spawn the researcher. Cheapest mode for the correction-without-replanning loop. If no RESEARCH.md exists yet, errors with a hint to drop --view.

Orchestrator role: Parse arguments, validate phase, research domain (unless skipped), spawn gsd-planner, verify with gsd-plan-checker, iterate until pass or max iterations, present results.

<execution_context> @/.claude/gsd-core/workflows/plan-phase.md @/.claude/gsd-core/references/ui-brand.md </execution_context>

<runtime_note> Copilot (VS Code): Use vscode_askquestions wherever this workflow calls AskUserQuestion. They are equivalent — vscode_askquestions is the VS Code Copilot implementation of the same interactive question API. Do not skip questioning steps because AskUserQuestion appears unavailable; use vscode_askquestions instead. </runtime_note>

Flags:

  • --research — Force re-research even if RESEARCH.md exists
  • --skip-research — Skip research, go straight to planning
  • --gaps — Gap closure mode (reads VERIFICATION.md, skips research)
  • --skip-verify — Skip verification loop
  • --prd <file> — Use a PRD/acceptance criteria file instead of discuss-phase. Parses requirements into CONTEXT.md automatically. Skips discuss-phase entirely.
  • --ingest <path-or-glob> — Use one or more ADR files instead of discuss-phase. Parses locked decisions + scope fences into CONTEXT.md automatically. Skips discuss-phase entirely.
  • --ingest-format <auto|nygard|madr|narrative> — Optional ADR parser format override (auto default).
  • --reviews — Replan incorporating cross-AI review feedback from REVIEWS.md (produced by /gsd-review)
  • --text — Use plain-text numbered lists instead of TUI menus (required for /rc remote sessions)
  • --mvp — MVP enrichment on top of the default tracer-first ordering: frames the phase goal as a user story and, on Phase 1 of a new project, also emits SKELETON.md (Walking Skeleton). Vertical slicing itself is now the default (see --no-tracer); --mvp no longer turns it on. Can be persisted on a phase via **Mode:** mvp in ROADMAP.md.
  • --no-tracer — Opt out of the default tracer-first decomposition and plan horizontal layers (the legacy default). By default every plan LEADS with one production-quality end-to-end tracer slice that is verified before any expansion task.
  • --no-reversibility-gates — Suppress the human checkpoint that a one-way-door decision normally earns, for runs you intend to leave unattended. By default a decision rated one-way (undo needs a migration, breaks a published contract, or is impossible) gets a checkpoint:decision before the task implementing it. Ratings are still recorded on tasks and costly items still flagged — the flag changes what stops the run, not what the plan remembers.

Read the full file on GitHub · 65 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. 7d ago First seen · 65 lines · 16 tokens per session scan A 4ae27cbd263d

Subscribe to this mod's changes

gsd-plan-phase is a skill published in the GitHub repository open-gsd/gsd-core (9,319 stars, last pushed today), licensed MIT. It adds 16 tokens to every session and 1,215 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 2026-09-03.

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