synthesis-code-planning

synthesis-code-planning is a skill for Claude Code, Codex from synthesisengineering/synthesis-skills. It costs 61 tokens per session (693 once invoked), scanned A, original, Apache-2.0.

A structured method for planning coding tasks before implementation. It examines the request and existing code, compares at least two possible approaches, and then selects one to build.

In plain words
What is it for?
Use it when generating code, implementing a feature, or tackling a coding task that could be solved in several ways.
Why use it?
It reduces guesswork and makes trade-offs visible before code is written. It also prompts the agent to consider project constraints, documentation, performance, and correctness.

Skill for Claude CodeCodex

Written for Claude Code and Codex: user-invocable in frontmatter, but also agents/openai.yaml present.

Part of the synthesis-skills plugin — 63 skills, 4 hooks shipped together

Good fit Use it when generating code, implementing a feature, or tackling a coding…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/synthesisengineering/synthesis-skills/synthesis-code-planning
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 synthesisengineering/synthesis-skills --skill synthesis-code-planning
Clone the repo
git clone --depth 1 https://github.com/synthesisengineering/synthesis-skills

Made for: Claude Code, Codex.

Or install synthesis-skills, the plugin that ships this one along with the rest of its 63 skills, 4 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 synthesis-code-planning

README.md
[![agentmods](https://agentmods.dev/badge/skills/synthesisengineering/synthesis-skills/synthesis-code-planning.svg)](https://agentmods.dev/skills/synthesisengineering/synthesis-skills/synthesis-code-planning)
Your own site
<a href="https://agentmods.dev/skills/synthesisengineering/synthesis-skills/synthesis-code-planning"><img src="https://agentmods.dev/badge/skills/synthesisengineering/synthesis-skills/synthesis-code-planning.svg" alt="Measured on agentmods" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 693 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.
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 $0.00061 $0.00693
Opus 5 $0.00030 $0.00347
Sonnet 5 $0.00012 $0.00139
Haiku 4.5 $0.00006 $0.00069

Measured 7d ago against content hash ef0efb94adee, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

synthesis-code-planning 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/synthesis-code-planning/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Planning

A structured methodology for approaching code tasks that produces higher-quality implementations by evaluating multiple approaches before committing to one.

Inputs

Before generating code, gather three inputs:

  1. Task description -- what needs to be built or changed
  2. Existing code -- the current codebase or relevant files (if any)
  3. Contextual documentation -- relevant API docs, framework guides, coding standards, or architectural decisions

Process

Step 1: Analyze

Carefully analyze the task description and existing code. Consider:

  • What is the actual goal (not just the literal request)?
  • What constraints does the existing code impose?
  • What are the performance, maintainability, and correctness requirements?
  • What best practices apply to this language, framework, or domain?

Step 2: Generate approaches

Produce at least two distinct approaches to address the task. For each approach, document:

Approach 1: [Brief description]

  • Pros:
    • [Advantage 1]
    • [Advantage 2]
  • Cons:
    • [Drawback 1]
    • [Drawback 2]

Approach 2: [Brief description]

  • Pros:
    • [Advantage 1]
    • [Advantage 2]
  • Cons:
    • [Drawback 1]
    • [Drawback 2]

Generate more approaches when the problem space is ambiguous or when the first two approaches have significant trade-offs against each other.

Step 3: Evaluate and select

Select the optimal solution and justify the choice with specific reasoning:

  • Reference the pros and cons of each approach
  • Explain why the chosen approach best addresses the task requirements
  • Acknowledge what is sacrificed by not choosing the alternatives
  • If the decision is close, state that explicitly

Step 4: Implement

Implement the chosen solution by modifying or creating code:

  • Mark changes clearly when modifying existing code
  • Follow the conventions and patterns already present in the codebase
  • Optimize for performance, maintainability, and adherence to best practices
  • Include necessary error handling and edge case coverage

Read the full file on GitHub · 87 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 87 lines · 61 tokens per session scan A ef0efb94adee

Subscribe to this mod's changes

synthesis-code-planning is a skill published in the GitHub repository synthesisengineering/synthesis-skills (18 stars, last pushed today), licensed Apache-2.0. It adds 61 tokens to every session and 693 once invoked, about $0.0003 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.

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