03-design-tradeoffs

03-design-tradeoffs is a cursor rule for Cursor from AG-Dmitry/composer-enhanced. It costs 27 tokens per session (612 once invoked), scanned A, original, MIT.

A planning rule for choosing a coding approach before implementation, including alternatives, trade-offs, edge cases, and error paths.

In plain words
What is it for?
Use it before medium or complex changes to outline the files and design, reject an alternative, and record the decision.
Why use it?
It reduces rework caused by committing too quickly to the first plausible solution.

Cursor rule for Cursor

Written for Cursor: a Cursor rule (.mdc). Also seen: mentions subagents.

Good fit Use it before medium or complex changes to outline the files and design, reject an alternative, and record the decision.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/ag-dmitry/composer-enhanced/03-design-tradeoffs
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.

Clone the repo
git clone --depth 1 https://github.com/AG-Dmitry/composer-enhanced

Made for: Cursor.

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 03-design-tradeoffs

README.md
[![agentmods](https://agentmods.dev/badge/rules/ag-dmitry/composer-enhanced/03-design-tradeoffs.svg)](https://agentmods.dev/rules/ag-dmitry/composer-enhanced/03-design-tradeoffs)
Your own site
<a href="https://agentmods.dev/rules/ag-dmitry/composer-enhanced/03-design-tradeoffs"><img src="https://agentmods.dev/badge/rules/ag-dmitry/composer-enhanced/03-design-tradeoffs.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 612 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 $0.00027 $0.00612
Opus 5 $0.00014 $0.00306
Sonnet 5 $0.00005 $0.00122
Haiku 4.5 $0.00003 $0.00061

Measured 7d ago against content hash eb5fd5a28d3f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

03-design-tradeoffs 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.

agent-protocols/03-design-tradeoffs.mdc · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Phase 3 — Design & Trade-offs

Persona: Planner. No code in this phase.

Cheap models grab the first plausible approach and commit. Forcing a second option and an edge-case sweep here prevents expensive rework later.

Steps

  1. Sketch the chosen approach at a high level: which files change, what the shape of the change is, and how it satisfies each success criterion from phase 1.

  2. Name at least one alternative (required for medium-high and high complexity). State why you rejected it. One sentence each is fine. This forces you out of first-idea tunnel vision.

  3. Enumerate edge cases and error paths up front:

    • Empty / null / undefined inputs.
    • Async failures, races, cancellation, cleanup.
    • Boundary values (0, 1, max, off-by-one).
    • Existing behavior that must not regress. Decide how each is handled now, not after a bug appears.
  4. Confirm scope discipline. The plan must be the minimal diff that meets the criteria — no speculative features, no "while I'm here" refactors.

  5. Record the decision as immutable. Write the chosen design + rejected alternatives + rationale into the Decision log of the task-memory file. In later retries you may not silently reverse this decision; if you must change it, add a new dated entry explaining why. This is the main guard against the retry oscillation loop.

Optional: stronger model for design on high-complexity tasks

For tasks classified high in phase 1, if the design space is genuinely ambiguous or architectural (multiple valid architectures with long-term consequences), you may spawn a planning subagent with a stronger model before committing to an approach:

Task(
  description: "Design consultant",
  subagent_type: "generalPurpose",
  readonly: true,
  model: "claude-4.6-sonnet-medium-thinking",
  prompt: "Given this goal and constraints [paste from working memory], propose
           and compare two architectures. Return trade-offs and a recommendation.
           Do not implement — design only."
)

Read the full file on GitHub · 70 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 · 70 lines · 27 tokens per session scan A eb5fd5a28d3f

Subscribe to this mod's changes

03-design-tradeoffs is a cursor rule published in the GitHub repository AG-Dmitry/composer-enhanced (3 stars, last pushed 2mo ago), licensed MIT. It adds 27 tokens to every session and 612 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 2026-08-31.