15 Best Claude Code Prompts and System Templates in 2026

Claude Code changed how serious engineers ship in 2025. By 2026, the question is no longer "should I use it" but "what prompts make it behave like a senior engineer instead of a confident intern." The model is strong. The harness is strong. What separates teams shipping with it from teams flailing with it is the prompt layer — the CLAUDE.md system templates, the planning rituals, the review loops.

The hard part is that most published "Claude Code prompts" online are screenshots from launch week. They look impressive in a tweet and break the moment you point them at a real repo with 40k lines of code, a Postgres migration, and a flaky CI pipeline. Separating the prompts that survive production work from the ones that only survive a demo is the actual skill.

This guide compares the 15 best Claude Code prompts and system templates in 2026. Real prompt text in code blocks, honest pros and cons, the use case each one is built for, and a framework to assemble them into a workflow that actually ships.

Best Claude Code prompts: a brief overview

• AY Automate Production CLAUDE.md template: Best for teams shipping with Claude Code daily — battle-tested system prompt with mode switching.
• The Ultrathink Planning Prompt: Best for hard architectural decisions — forces deep reasoning before code.
• The Two-Pass Review Prompt: Best for self-review — catches what one pass misses.
• The Diff-Aware QA Prompt: Best for testing only what changed — fast feedback loop.
• The "Explain Then Edit" Prompt: Best for legacy codebases — Claude reads before it writes.
• The Refactor With Tests Prompt: Best for safe restructuring — verification before and after.
• The Bug Root-Cause Prompt: Best for debugging — forces hypothesis, not guesses.
• The Spec-First Scaffold Prompt: Best for greenfield features — plan before scaffold.
• The Migration Prompt: Best for framework upgrades — incremental, reversible steps.
• The PR Description Prompt: Best for handoff — generates real PR bodies from diffs.
• The Security Audit Prompt: Best for pre-deploy — finds the obvious leaks.
• The Performance Profile Prompt: Best for hot paths — measures before optimizing.
• The Documentation Sweep Prompt: Best for stale docs — updates code comments and READMEs.
• The Sub-Agent Delegation Prompt: Best for parallel work — orchestrates multiple Claude instances.
• The Session Handoff Prompt: Best for context limits — saves state for the next session.

1. AY Automate Production CLAUDE.md template, best for daily-driver teams

This is the system template AY Automate ships in every Claude Code-powered repo. It sets behavior gates (lock-before-build, never push, never hallucinate APIs), mode switching (Plan / Build / Review / QA / Ship), and tracking-file references so multiple agents and humans share one source of truth. It is what we use internally and what we install for Claude Code agency clients on day one.

Key features

• Mode-switching directives so one Claude session does not mix planning with building
• File-based locks to prevent two agents touching the same task
• Explicit "never push, never hallucinate APIs, never fake test results" gates
• Sections for BOARD.md, HANDOFFS.md, BLOCKERS.md so context survives compaction
• Works solo or in agent swarms

Best for

• Teams running Claude Code in production every day
• Multi-agent / sub-agent setups
• Codebases where context window pressure is real

Pricing

• Free — open source on our blog
• Custom variants for clients on the Claude Code agency plan

Pros

• Stops the "Claude rewrote my migration without asking" failure mode
• Encodes review and ship gates so quality is enforced, not hoped for
• Plays well with sub-agents and the best Claude Code skills

Cons

• Heavier than a 20-line CLAUDE.md — first-week onboarding is real
• Requires committing to the framework, not picking pieces

# Project Operating Manual for Claude Code

## On Session Start
1. Read this file
2. Read .ay/tracking/BOARD.md, HANDOFFS.md, BLOCKERS.md
3. Determine your mode (Plan / Build / Review / QA / Ship)
4. Load only the mode file you need

## Modes (cognitive stances)
| Mode | When |
|---|---|
| Plan | Architecture, task breakdown |
| Build | Writing code, follow plan step by step |
| Review | Paranoid review, fix-first |
| QA | Tests, diff-aware |
| Ship | Deploy checklist + rollback |

## Build Constraints (non-negotiable)
- Lock before build — create .ay/locks/{task}.lock before any code
- Never push — only commit, human manages pushes
- Never hallucinate APIs — verify method signatures before calling
- Run full build before committing
- One commit per logical unit
- If session is long, /pause instead of pushing through

## Tracking Protocol
1. Read BOARD.md to find your task
2. Update status to IN PROGRESS
3. Work in scoped directories only
4. When done: update BOARD, write HANDOFF entry, log in AGENTS-LOG.md

2. The Ultrathink Planning Prompt, best for hard architectural decisions

"Ultrathink" started as a community pattern and became the standard way to make Claude actually reason instead of pattern-match. You prefix the architectural question with ultrathink (or think hard / think harder), then constrain the output to a structured plan with explicit trade-offs.

Key features

• Triggers extended reasoning budget on supported models
• Forces the model to enumerate options before picking one
• Output format encourages trade-off analysis, not just "here is the answer"

Best for

• Database schema choices
• Migration strategy decisions
• Picking between two libraries
• Anything where the wrong choice costs a week

Pricing

• Free

Pros

• Surfaces options you would have missed
• Reduces "Claude confidently picked the wrong abstraction" bugs
• Pairs well with the Two-Pass Review prompt below

Cons

• Slower — extended thinking takes longer
• Overkill for small tasks; do not use for "rename this variable"

ultrathink

I need to decide: {decision}.

Constraints:
- {constraint 1}
- {constraint 2}
- {constraint 3}

Output format:
1. Restate the problem in your own words
2. List 3-5 viable options
3. For each option: pros, cons, hidden costs, reversibility
4. Recommend ONE option with explicit reasoning
5. List the 3 things most likely to go wrong with the recommendation

3. The Two-Pass Review Prompt, best for self-review

One pass catches bugs. Two passes catch the bugs the first pass introduced. This prompt makes Claude review its own output twice with different lenses — first for correctness, second for quality.

Key features

• Pass 1: correctness, security, edge cases (fix-first)
• Pass 2: readability, naming, dead code, performance
• Outputs a structured report you can paste into a PR

Best for

• Pre-commit self-review
• Pre-PR cleanup
• Anything touching auth, payments, migrations

Pricing

• Free

Pros

• Catches issues a single pass misses
• Produces PR-ready notes
• Reusable across languages

Cons

• Doubles review time
• Pass 2 can over-engineer if you do not constrain it

You are in REVIEW mode. Do NOT write new features.

Review the diff in two passes.

PASS 1 — Correctness (fix-first)
- Does the code do what the plan says?
- Edge cases: nulls, empty arrays, off-by-one, race conditions
- Security: input validation, auth checks, secrets, SQL injection
- Errors: are failures handled or silently swallowed?

Fix everything you can in this pass. Show the diff.

PASS 2 — Quality
- Naming: do names match what the thing does?
- Dead code: anything that is no longer reachable?
- Readability: would a new engineer understand this in 30 seconds?
- Performance: any obvious O(n²) on hot paths?

Output a numbered list of findings with severity (blocker / nit).

4. The Diff-Aware QA Prompt, best for fast CI feedback

Running the full test suite on every change wastes time. This prompt tells Claude to run only the tests that touch the files in the diff, then escalate to broader suites only if those pass.

Key features

• Maps changed files to relevant test files
• Runs minimal test set first
• Escalates to integration / e2e only after units pass
• Reports timing per layer

Best for

• Pre-commit hooks
• CI optimization
• Monorepos where the full suite is 20+ minutes

Pricing

• Free

Pros

• 5-10× faster feedback loop
• Catches "I broke this other file" via dependency walk
• Honest output — tells you what it skipped

Cons

• Misses cross-cutting failures (still run full suite before merge)
• Requires reasonable test naming conventions

You are in QA mode.

Step 1: Run `git diff --name-only` and list changed files.
Step 2: For each changed file, find related test files (same name, same module).
Step 3: Run unit tests for those files first. Report pass/fail.
Step 4: If units pass, run integration tests that import the changed modules.
Step 5: If integration passes, run e2e tests that hit the affected routes.
Step 6: Output a table: layer | tests run | passed | failed | duration.

Do NOT run the full suite. Do NOT mark anything green without seeing the test output.

5. The "Explain Then Edit" Prompt, best for legacy code

Claude is dangerous in legacy code when it edits before it understands. This prompt forces a read-and-explain pass before any change.

Key features

• Forces Claude to summarize the file's purpose first
• Lists callers and dependencies before editing
• Surfaces hidden assumptions

Best for

• Inherited codebases
• Files you did not write
• Anything with implicit business logic

Pricing

• Free

Pros

• Prevents "Claude removed the line that was actually critical"
• Documents the file as a side effect
• Surfaces dead-code and hidden coupling

Cons

• Slower than just editing
• Annoying for trivial changes

Before editing {file}, do this:

1. Read the file end-to-end.
2. Summarize in 3 bullets: what it does, who calls it, what it depends on.
3. List the top 3 non-obvious behaviors (gotchas, side effects, magic).
4. Show me a diff PLAN (not code) of what you propose to change.
5. Wait for my approval before writing code.

6. The Refactor With Tests Prompt, best for safe restructuring

Refactors fail when tests fail silently. This prompt runs tests before and after, refuses to commit if the before-state is red.

Key features

• Captures green test state first
• Refactors in small steps
• Re-runs tests after each step
• Rolls back on regression

Best for

• Renaming across files
• Extracting modules
• Restructuring imports

Pricing

• Free

Pros

• Verifiable safety
• Small reversible commits
• Catches accidental behavior changes

Cons

• Requires existing test coverage
• Slow for large refactors — but that is the point

You are refactoring. Follow this loop strictly:

1. Run the test suite. If anything is red, STOP — tell me, do not refactor on red.
2. Capture the green state (test counts, timings).
3. Plan the refactor in 3-7 small steps. Show me the steps.
4. For each step:
   a. Make the change.
   b. Run relevant tests.
   c. If green, commit with message "refactor(step N): {what}".
   d. If red, revert the step and tell me.
5. After all steps, run the full suite. Confirm state matches the captured baseline.

7. The Bug Root-Cause Prompt, best for production bugs

Most debugging prompts ask "fix this bug." The better prompt asks "what is the root cause, and what else does it affect." This one forces hypothesis-driven debugging.

Key features

• Forces a hypothesis before any code
• Requires reproduction steps
• Surfaces related bugs you did not report

Best for

• Production incidents
• Flaky tests
• "Works on my machine" bugs

Pricing

• Free

Pros

• Stops the "Claude fixed the symptom, not the cause" pattern
• Finds adjacent bugs
• Produces a root-cause writeup for the postmortem

Cons

• Slower than band-aid fixes
• Sometimes the right answer IS a band-aid (deadline) — override the prompt then

You are debugging. Follow this loop.

1. Restate the bug in your own words.
2. List 3 hypotheses for the root cause, ranked by likelihood.
3. For each hypothesis, describe how you would verify it (specific files, specific assertions).
4. Verify hypothesis #1. Report what you found.
5. If verified, propose a fix. List 2 places where the same root cause might bite us next.
6. If not verified, move to hypothesis #2.

Do NOT write a fix until a hypothesis is verified.

8. The Spec-First Scaffold Prompt, best for new features

This prompt forces a spec-driven scaffold. Claude writes the spec, you approve it, then it scaffolds — never the other way.

Key features

• Spec → approval → scaffold
• Lists files to be created with one-line purpose
• Generates types and tests before implementation

Best for

• New API endpoints
• New UI features
• Anything with more than 3 files

Pricing

• Free

Pros

• Forces alignment before code is written
• The spec doubles as PR description
• Scaffolds compile because types come first

Cons

• Adds 10-15 minutes before first line of code
• Overkill for one-file changes

You are scaffolding a new feature: {feature}.

Phase 1 — Spec (do not write code yet):
- User story in 1-2 sentences
- API surface: endpoints, methods, request/response shapes
- Data model: new tables/columns, relationships
- Files to create or modify, with 1-line purpose each
- Acceptance criteria as a checklist

Stop. Wait for my approval.

Phase 2 — Scaffold (after approval):
- Create types/interfaces first
- Stub functions with TODOs
- Write failing tests for the acceptance criteria
- Implement just enough to make tests pass

9. The Migration Prompt, best for framework upgrades

Framework upgrades (Next.js 14 → 16, React 18 → 19) break in non-obvious ways. This prompt runs the upgrade in reversible steps with verification at each one.

Key features

• Reads the official upgrade guide first
• Runs codemods when available
• Bisects on regression
• Commits per step

Best for

• Major version bumps
• Library migrations
• Type-system upgrades

Pricing

• Free

Pros

• Reversible — every step is its own commit
• Surfaces breaking changes early
• Pairs well with the best Claude Code skills for migration

Cons

• Slower than "yolo upgrade"
• Requires the upgrade guide to actually exist

You are migrating {library} from {oldVersion} to {newVersion}.

Step 1: Fetch the official upgrade guide. Summarize breaking changes.
Step 2: Run any official codemod. Commit the result with message "chore: run {library} codemod".
Step 3: Run the build. If green, commit. If red, fix one error at a time, commit each fix.
Step 4: Run the test suite. Same loop — green commit, red fix-and-commit.
Step 5: Run the app. Smoke-test the 3 most critical user flows.
Step 6: Output a migration report: what changed, what broke, what is risky.

Never bundle multiple breaking-change fixes in one commit.

10. The PR Description Prompt, best for team handoff

A PR description that says "fix bug" wastes everyone's time. This prompt generates a real PR body from the diff and recent commits.

Key features

• Reads diff + commit messages
• Produces summary, motivation, test plan, screenshots section
• Lists files changed with one-line rationale

Best for

• Solo devs whose PRs reviewers hate
• Teams with PR templates
• Open-source contributors

Pricing

• Free

Pros

• Reviewers read it
• Saves 10 minutes per PR
• Produces a paper trail

Cons

• Generic if you do not edit it
• Cannot replace the "why" — that has to come from you

Generate a PR description from the current branch.

Read: git log main..HEAD, git diff main..HEAD --stat, git diff main..HEAD.

Output this exact structure:

## Summary
{2-3 sentences — what this PR does, not how}

## Motivation
{Why is this needed? Link issues if mentioned in commits.}

## Changes
- {Bullet per logical change, with file references}

## Test plan
- [ ] {Concrete reproducible step 1}
- [ ] {Concrete reproducible step 2}

## Risks / rollback
{What could break, how to revert}

## Screenshots / notes
{Placeholder section if UI changed}

11. The Security Audit Prompt, best for pre-deploy

Not a replacement for a real audit, but catches the obvious leaks before a deploy.

Key features

• Scans for hardcoded secrets, weak auth checks, SQL injection patterns
• Checks dependency advisories
• Flags exposed env vars in client bundles

Best for

• Pre-launch checklist
• Pre-investor demo
• After accepting external PRs

Pricing

• Free

Pros

• Catches the embarrassing stuff
• Fast — minutes, not hours
• Produces a checklist you can sign off on

Cons

• NOT a substitute for a real security audit
• High false-positive rate on dependency advisories

Run a security audit on the current branch. Focus on OBVIOUS issues only.

Scan for:
1. Hardcoded secrets: API keys, tokens, passwords, connection strings
2. SQL injection: string concatenation in queries, missing parameterization
3. Auth gaps: routes without auth middleware, role checks missing on mutations
4. Client-side leaks: env vars without NEXT_PUBLIC_ prefix exposed in client code
5. Dependency advisories: run npm audit / pnpm audit, surface CRITICAL and HIGH only
6. Open CORS: wildcard origins in production
7. Missing input validation on user-facing endpoints

Output a table: category | file | line | severity | suggested fix.
Do NOT auto-fix. List for human review.

12. The Performance Profile Prompt, best for hot paths

Measure first, optimize second. This prompt forces measurement before any change.

Key features

• Identifies the hot path with profiling data
• Measures baseline before changing anything
• Re-measures after each change

Best for

• API latency complaints
• Slow page loads
• Memory leaks

Pricing

• Free

Pros

• Stops premature optimization
• Produces before/after numbers for the PR
• Surfaces the real bottleneck (often not where you thought)

Cons

• Requires a way to measure (profiler, traces, timing logs)
• Slower than yolo-optimizing

Performance work. Do NOT optimize before measuring.

Step 1: Reproduce the slow path. Capture timing (use profiler / Chrome perf tab / k6 / wrk).
Step 2: Report the baseline: p50, p95, p99, where time is spent (% per function).
Step 3: Identify the top 1-2 hotspots. Propose ONE change at a time.
Step 4: Apply the change. Re-measure. Report the delta.
Step 5: If improvement < 10%, revert and try the next hypothesis.
Step 6: When done, output a before/after table with the numbers.

13. The Documentation Sweep Prompt, best for stale docs

Docs rot. This prompt walks the repo, finds stale comments and outdated READMEs, and proposes fixes.

Key features

• Compares JSDoc / docstrings to current function signatures
• Flags README sections that reference removed files
• Updates code examples that no longer compile

Best for

• Open-source repos
• Onboarding-heavy codebases
• After big refactors

Pricing

• Free

Pros

• Catches lies in your docs
• Improves new-hire ramp time
• Cheap insurance

Cons

• Can be overly aggressive — review before merging
• Cannot detect "the doc is right but the explanation is bad"

You are sweeping documentation. Do NOT change runtime behavior.

For each file in {scope}:
1. Compare function signatures to JSDoc / docstring parameters. Flag mismatches.
2. Compare README code examples to the actual API. Flag any that would not compile or run.
3. Find references to deleted files / functions. Flag.
4. List functions over 20 lines with no doc comment. Suggest one-sentence summaries.

Output a checklist. Make changes only after I approve specific items.

14. The Sub-Agent Delegation Prompt, best for parallel work

When one Claude session is not enough, this prompt orchestrates a swarm. Each sub-agent gets a scoped task, the orchestrator tracks completion.

Key features

• Defines sub-agent scope and inputs
• Tracks completion via files (no shared memory)
• Re-runs failed sub-agents

Best for

• 40+ parallel tasks (like generating a batch of blog posts)
• Multi-file refactors with independent units
• Documentation generation across many modules

Pricing

• Free

Pros

• Real parallelism
• Each sub-agent fits in its own context window
• Failures isolated

Cons

• Coordination overhead
• Requires a tracking file (BOARD.md or similar)
• See the best Claude Code GitHub repos for working examples

You are the orchestrator. Spawn N sub-agents in parallel using the Task tool.

For each sub-agent:
- Give it ONE scoped task from BOARD.md
- Tell it to write its output to {scoped path}
- Tell it: "MUST NOT touch any other file"
- Tell it: "Report back with: file path, status, issues"

After all sub-agents return:
1. Compile a status table: task | status | output file | issues
2. Re-queue any failures
3. Stop when BOARD shows all tasks DONE

15. The Session Handoff Prompt, best for context limits

Claude Code sessions hit context walls. This prompt saves state so the next session continues without forgetting what happened.

Key features

• Snapshots open files, current task, next steps
• Writes a HANDOFF.md another session can read
• Lists assumptions made and open questions

Best for

• Long projects
• Multi-day features
• Handing off to a teammate

Pricing

• Free

Pros

• Survives context compaction
• Next session ramps in 30 seconds
• Doubles as a journal

Cons

• Requires discipline to actually run it before context dies
• Stale handoffs are worse than none

You are pausing the session. Write .ay/sessions/{date}-{topic}.md with this structure:

## Where I am
- Active task: {task name}
- Active files: {list}
- Last commit: {sha + message}

## What I just did
- {3-5 bullets of recent work}

## What is next
- {Next 1-3 steps the resumer should take}

## Open questions / assumptions
- {Decisions deferred to next session}

## How to resume
- Run: git status
- Read: this file
- Then: {specific next command}

How to choose the best Claude Code prompts

1) What stage of work are you in?

If you are starting a new feature, lead with the Spec-First Scaffold Prompt (#8) and the Ultrathink Planning Prompt (#2). If you are mid-build, use the AY Automate CLAUDE.md template (#1) plus the Diff-Aware QA Prompt (#4) for fast feedback. If you are pre-PR, run the Two-Pass Review Prompt (#3) and the PR Description Prompt (#10). Pre-deploy: Security Audit (#11) and Performance Profile (#12). Each prompt is a tool — using them out of order wastes time.

2) Are you working solo or in a swarm?

Solo work fits most prompts as-is. Swarm work (multiple Claude Code sessions, sub-agents, multiple humans) requires the AY Automate CLAUDE.md template (#1) and the Sub-Agent Delegation Prompt (#14) layered together. Without a shared tracking file (BOARD.md), parallel sub-agents step on each other's work. We cover the orchestration patterns in detail on the Claude Code agency service page and in our breakdown of the best Claude Code GitHub repos.

3) How big is the codebase?

Small repos (under 5k LOC) can skip the Explain-Then-Edit pass — Claude will load the whole repo into context. For medium repos (5k-50k LOC), the Explain Then Edit Prompt (#5) and the Documentation Sweep Prompt (#13) become essential — Claude needs guardrails to understand what it is touching. For large repos (50k+ LOC), layer the best Claude Code skills on top of these prompts so domain knowledge is loaded on demand instead of all at once.

4) How critical is correctness?

For non-critical scripts, skip the heavyweight review prompts — speed matters more. For anything touching production data, auth, or payments, run the Two-Pass Review Prompt (#3), then the Security Audit Prompt (#11), then the Bug Root-Cause Prompt (#7) if anything looks suspicious. The cost of these prompts is minutes. The cost of skipping them is incidents.

Want Claude Code installed properly the first time?

Most of these prompts came out of real production work with clients who needed Claude Code to behave like a senior engineer, not a confident demo. AY Automate ships the full system — CLAUDE.md templates, sub-agent orchestration, tracking layer, review and QA gates — on day one. See the Claude Code agency page for what installation looks like, browse our complete catalog of the best Claude Code skills to pair with these prompts, or check the top Claude Code GitHub repos for working examples in the wild. Ready to skip the trial-and-error phase? Book a free consultation and we will audit your current Claude Code setup.

FAQ

What is a Claude Code prompt?

A Claude Code prompt is any instruction you give Claude inside the Claude Code CLI — either in your CLAUDE.md system file, in a session message, or as a slash command. The best prompts encode behavior gates ("never push, never hallucinate APIs"), workflow steps (plan → build → review → ship), and output formats so Claude's responses are predictable instead of creative.

How is a Claude Code prompt different from a regular ChatGPT prompt?

Claude Code prompts assume an agentic loop — Claude is reading files, writing files, running commands, and committing code. A ChatGPT prompt assumes a single response. That changes everything: Claude Code prompts focus on multi-step protocols, file-based state, and review gates, while ChatGPT prompts focus on tone, format, and constraints on a single output.

How do I verify a Claude Code prompt actually works?

Run it against a repo you know cold. If the output matches what a senior engineer would produce in the same situation, the prompt is good. If Claude takes shortcuts, hallucinates APIs, or skips verification, the prompt needs more constraints — usually explicit "never" gates and structured output formats.

How much does it cost to use Claude Code prompts in 2026?

The prompts themselves are free. Claude Code usage is billed by Anthropic per token through your API key or Claude Pro plan. Heavy ultrathink-style prompts cost more than simple ones — but the cost of one extended-reasoning session is still cheaper than a single hour of senior engineer time.

How long does it take to set up a good CLAUDE.md?

A minimal CLAUDE.md takes 30 minutes. A production CLAUDE.md with mode switching, lock protocols, and tracking files takes 2-4 hours the first time you build one — then 15 minutes to copy into the next repo. The AY Automate template at the top of this guide is the result of dozens of iterations across real projects.

Is "ultrathink" an official Anthropic feature?

It is a community pattern that maps to Claude's extended reasoning budget on supported models. Using the word "ultrathink" (or "think hard" / "think harder") signals you want more reasoning before the answer. Anthropic documents the extended-thinking feature directly — the community just landed on "ultrathink" as the trigger word.

Should I use these prompts or write my own?

Both. Start with these as a baseline so you do not reinvent obvious patterns, then customize for your stack and team conventions. A prompt that works for a Next.js + Postgres team needs adjustment for a Rust + Kafka team. The structure stays — the specifics change.

Can these prompts train my internal team?

Yes — and that is half their value. A team that copies the Two-Pass Review prompt for every PR ends up internalizing the review checklist. After a few months, the engineers do the two passes without the prompt. The prompts are scaffolding for habits, not permanent crutches.