Plan gate

Plan Gate

Purpose

Prevent rushed execution. A wrong start on complex work wastes more time than any plan costs. The gate: before making the first change on non-trivial work, a plan must exist in writing — visible to the user, not just implied.

Equally important: do not over-plan. A trivial task with a ceremony plan is as much a failure as a complex task with no plan.

When to use this skill

• The task has 3+ dependent steps, touches multiple files/sections, or has unclear requirements.
• The cost of a wrong start is high (large edits, irreversible actions, external-facing output).
• You feel the urge to "just start" on something you can't fully picture the end state of. That urge is the trigger.

When NOT to use this skill

• Single obvious step, reversible, under ~2 minutes of work (typo fix, rename, direct factual answer). Just do it.
• The user provided the plan and asked you to execute it. Confirm you understand it; don't rewrite it.
• Pure exploration/reading with no changes — go straight to live-state-truth instead.

Operating procedure

Step 1 — Pick the planning depth. Do this in your head; it takes five seconds.

Depth	Task size signals	Plan required
0 — None	One step, obvious, reversible	None. Execute.
1 — Micro	2–5 steps, familiar territory, low blast radius	One short paragraph: goal, steps, done-check
2 — Structured	Multi-file / multi-section, some unknowns, moderate stakes	Full template below
3 — Staged	Large, unfamiliar, or risky; can't hold it all in one plan	Template below + hand decomposition to deep-decomposition; plan only stage 1 in detail

Step 2 — Write the plan (Depth 2–3 template):

## Plan: <one-line goal>
**Success criteria:** How we'll know it worked — observable, checkable.
**Constraints:** Stated by the user + inferred (style, compatibility, deadline pressure).
**Assumptions:** What I'm taking as true without proof. (Each is a risk.)
**Risks:** Top 2–3 ways this goes wrong, and the mitigation for each.
**Steps:** First 3–5 concrete actions. (Later steps may be rough.)

Step 3 — Sanity-check the plan before executing.

• Does every success criterion have a way to check it?
• Is any assumption cheap to verify right now? Verify it first (live-state-truth).
• Is step 1 actually the smallest useful first step?

Step 4 — Execute against the plan. When reality contradicts the plan, update the plan visibly — say what changed and why. Don't silently drift.

Quality bar

• The plan is falsifiable: someone else could look at the success criteria and say "done" or "not done."
• Assumptions are written down, not embedded invisibly in the steps.
• The plan fits the task: a Depth-2 plan should be under ~15 lines.

Common failure modes

• Plan-as-theater: writing a plan, then ignoring it during execution. The plan is a contract, not a warm-up.
• Over-planning trivia: a 10-line plan for a one-line fix. Depth 0 exists; use it.
• Success criteria that restate the task ("implement X" → criterion "X is implemented"). Criteria must be observable checks, e.g. "the test suite passes and the new endpoint returns 200 for the sample payload."
• Frozen plans: refusing to revise when step 2 reveals the plan was wrong. Revise out loud.
• Planning past the horizon: detailing step 9 when steps 1–3 will change everything. Plan the near steps concretely, the far ones roughly.

Example

Bad (Depth mismatch): User: "rename this variable" → Model writes a 5-part plan. Wrong — Depth 0.

Good (Depth 2): User: "add rate limiting to the API"

## Plan: Add rate limiting to the public API
**Success criteria:** New test: burst over the limit returns 429. New test: same burst under the limit returns all 200s. Existing suite stays green (run it, quote the summary line).
**Constraints:** No new external service (inferred: single-node deploy).
**Assumptions:** Middleware layer exists where this can hook in — verify first.
**Risks:** Breaking auth middleware ordering → check middleware chain before inserting.
**Steps:** 1) Read current middleware setup. 2) Pick limiter approach that fits it. 3) Implement behind existing middleware. 4) Add over/under-limit tests. 5) Run full suite.

Works with sibling skills

• intent-clarity runs before this — you can't plan toward a goal you've misread.
• effort-calibration decides the depth tier; this skill defines what each tier requires.
• deep-decomposition takes over when the task is too big for one plan (Depth 3).
• change-control governs execution of the plan's edits; adversarial-verify checks the result against the success criteria.

Provenance and maintenance

Written 2026-07 as part of a portable, project-agnostic quality pack. Contains no repo-specific claims. To re-verify this skill still fits your setup: confirm .claude/skills/plan-gate/SKILL.md is being picked up (ask Claude "which skills apply to building a feature?") and that the depth table still matches how your team sizes tasks. Update the template if your projects need extra fields (e.g., security review, stakeholder sign-off).