slice-planning

A planning skill that breaks development work into small slices, with each slice covering one observable behavior or structural change. GSD refers to a roadmap-style development process used by this skill.

In plain words
What is it for?
Use it when planning features, decomposing large tasks, or breaking down fixes that have taken too long. It writes the plan under the project's .planning/ directory.
Why use it?
It helps prevent plans from becoming too large or vague to execute safely. It also provides a way to split oversized work into smaller, resumable units.

Skill for Claude CodeCodex

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 skills/nerds-odd-e/doughnut/slice-planning
Any agent
npx skills add nerds-odd-e/doughnut --skill slice-planning
Clone the repo
git clone --depth 1 https://github.com/nerds-odd-e/doughnut

Made for: Claude Code, Codex.

Per session 83 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,283 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 $0.00083 $0.02283
Opus 5 $0.00042 $0.01141
Sonnet 5 $0.00017 $0.00457
Haiku 4.5 $0.00008 $0.00228

Measured 3d ago against content hash 7c32f97b18cb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

slice-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 3d 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.

.agents/skills/slice-planning/SKILL.md · 222 lines

How it starts

The opening of the file, as written. The whole thing — 222 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GSD phase is a roadmap capability (/gsd-plan-phase, .planning/phases/NN-slug/). This skill writes slices inside a plan.

Use when planning, splitting an oversized slice, or when a fix / make-test-pass attempt has overrun the breakdown time-box. If /gsd-plan-phase output violates Behavior/Structure — rewrite until every plan unit is one slice.

Output: Written plan under .planning/ + summary ending with ## SLICE PLAN WRITTEN.

Where to put plans (GSD-aligned):

Location Use
.planning/phases/NN-slug/ GSD roadmap phases — *-CONTEXT.md, *-PLAN.md, *-SUMMARY.md, …
.planning/quick/NNN-slug/ Ad-hoc plans not yet on the roadmap
ongoing/ Legacy only — do not add new plans

Primary executable file: *-PLAN.md or PLAN.md. Sub-decomposition: additional *-PLAN.md in the same directory or clearly marked slice sections — each still Behavior/Structure.

History: keep resume-useful status and brief learnings while in progress; when the whole plan is done and shipped as code/permanent docs, clean up spent planning history (.cursor/rules/planning.mdc).

Git does not use the Nix prefix.

Elapsed Action
> 5 min Scrutinize the breakdown — too coarse? Prefer finer decompose, revert WIP, retry on a smaller slice
> 10 min Hard trigger unless good reason (long suite, external wait): stop implementing, revert/stash WIP, cut a smaller Behavior/Structure slice

For the hard trigger:

  1. Stop implementing.
  2. Summarize learnings (discoveries, blockers, partial progress).
  3. git stash -m "WIP: <brief description>" (or revert uncommitted WIP).
  4. Decompose remaining work (steps below).
  5. Write .planning/quick/NNN-slug/PLAN.md (next free NNN). Promote to phases/ when roadmap-bound.
  6. Report and wait (or execute the first smaller slice if already authorized).

Order scenarios from common / general toward more specific preconditions.

Solutions: First slices implement a narrow, concrete outcome. Later slices generalize or reuse only after real repetition — not a big generic framework up front.

Regression: If behavior already exists but has no automated test, prefer a dedicated slice: add a regression test and make it pass.

Extending tests: If similar behavior already has tests, extend them; avoid duplicate test code. Fold "test fails → pass" into the feature slice, or use a short slice where the new test fails first. Keep at most one intentionally failing test while driving a change.

Big refactor: If making the test pass needs a large structural change, plan that structure as its own slice before (or as the first cut of) the feature.

E2E-shaped slices: Each slice maps to an end-to-end scenario; different slices may use different preconditions. Add or extend tests in capability-named feature files (e.g. note_creation.feature) — never name files or scenarios after the GSD phase.

Still too big: Split by one small part of the outcome per slice.

Time budget when sizing slices: Each Behavior/Structure unit should be achievable by an agent/sub-agent in about 5 minutes wall-clock including targeted test runs (planning.mdc). Prefer many small slices over ones that routinely blow past 5–10 minutes.

Read the full file on GitHub · 222 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. 3d ago First seen · 222 lines · 83 tokens per session scan A 7c32f97b18cb

Subscribe to this mod's changes

slice-planning is a skill published in the GitHub repository nerds-odd-e/doughnut (49 stars, last pushed 3d ago), licensed MIT. It adds 83 tokens to every session and 2,283 once invoked, about $0.0004 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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