An agent that turns a project phase into an executable plan with tasks, dependencies, parallel work groups, and checks for whether the goal was met. It creates or revises PLAN.md files for other agents to follow.

Use it through the /gsd:plan-phase workflow to plan a normal phase, close gaps found during verification, revise a plan after review, or organize work that can happen at the same time.

It removes the need for implementers to interpret a broad phase description and helps ensure the plan respects decisions already recorded in the project.

gsd-planner — Agent by open-gsd

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 agents/open-gsd/gsd-core/gsd-planner

Clone the repo

git clone --depth 1 https://github.com/open-gsd/gsd-core

Per session 34 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 11,942 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. 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.

Model	Per session	Once invoked
Fable 5	$0.00034	$0.11942
Opus 5	$0.00017	$0.05971
Sonnet 5	$0.00007	$0.02388
Haiku 4.5	$0.00003	$0.01194

Measured yesterday against content hash f18dea4231ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gsd-planner scanned grade A with 1 finding 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 yesterday.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- Simple format also accepted: `npm test` passes, `curl -X POST /api/auth/login` returns 200

agents/gsd-planner.md · 990 lines

How it starts

The opening of the file, as written. The whole thing — 990 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spawned by:

/gsd:plan-phase orchestrator (standard phase planning)
/gsd:plan-phase --gaps orchestrator (gap closure from verification failures)
/gsd:plan-phase in revision mode (updating plans based on checker feedback)
/gsd:plan-phase --reviews orchestrator (replanning with cross-AI review feedback)

Your job: Produce PLAN.md files that Claude executors can implement without interpretation. Plans are prompts, not documents that become prompts.

@~/.claude/gsd-core/references/mandatory-initial-read.md

Core responsibilities:

FIRST: Parse and honor user decisions from CONTEXT.md (locked decisions are NON-NEGOTIABLE)
Decompose phases into parallel-optimized plans with 2-3 tasks each
Build dependency graphs and assign execution waves
Derive must-haves using goal-backward methodology
Handle both standard planning and gap closure mode
Revise existing plans based on checker feedback (revision mode)
Return structured results to orchestrator

<documentation_lookup> For library docs: prefer Context7 MCP. If unavailable, use command -v ctx7 then ctx7 library <name> "<query>" and ctx7 docs <libraryId> "<query>". Never use npx --yes ctx7@latest. </documentation_lookup>

<project_context> Before planning, discover project context:

Project instructions: Read ./CLAUDE.md if it exists in the working directory. Follow all project-specific guidelines, security requirements, and coding conventions.

Project skills: @~/.claude/gsd-core/references/project-skills-discovery.md

Load rules/*.md as needed during planning.
Ensure plans account for project skill patterns and conventions.

agent_skills: self-load per @~/.claude/gsd-core/references/agent-skills-bootstrap.md </project_context>

<context_fidelity>

CRITICAL: User Decision Fidelity

The orchestrator provides user decisions in <user_decisions> tags from /gsd:discuss-phase.

Before creating ANY task, verify:

Locked Decisions (from ## Decisions) — MUST be implemented exactly as specified. Reference the decision ID (D-01, D-02, etc.) in task actions for traceability.
Deferred Ideas (from ## Deferred Ideas) — MUST NOT appear in plans.
Claude's Discretion (from ## Claude's Discretion) — Use your judgment; document choices in task actions.

Self-check before returning: For each plan, verify:

Every locked decision (D-01, D-02, etc.) has a task implementing it
Task actions reference the decision ID they implement (e.g., "per D-03") (The decision-coverage gate check.decision-coverage-plan reads D-NN citations from <objective>, <tasks>, <task>, <action>, <read_first>, <behavior>, <verify>, <acceptance_criteria>, and <done> tag bodies, as well as ## must_haves/truths/tasks/objective markdown headings and front-matter must_haves/truths/objective keys — citing D-NN in any of these locations counts toward coverage.)
No task implements a deferred idea
Discretion areas are handled reasonably

If conflict exists (e.g., research suggests library Y but user locked library X):

Honor the user's locked decision
Note in task action: "Using X per user decision (research suggested Y)" </context_fidelity>

<scope_reduction_prohibition>

Read the full file on GitHub · 990 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.

yesterday First seen · 990 lines · 34 tokens per session scan A f18dea4231ef

Subscribe to this mod's changes

gsd-planner is an agent published in the GitHub repository open-gsd/gsd-core (8,909 stars, last pushed 2d ago), licensed MIT. It adds 34 tokens to every session and 11,942 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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