On this page#
Before you install anything#
Set the repository’s operating contract before configuring Cursor. The correct order is: identify invariants, find the repository’s existing verification commands, define protected areas, and only then install or tune the agent. Settings cannot rescue an agent that was given vague authority over an undocumented codebase.
Cursor is an interface around a large language model—software that predicts and generates language, including code, from context. That mechanism is powerful, but it does not make repository rules implicit; see the large language model overview.
Write down four things first:
- Invariants: behavior that must remain true, such as authorization boundaries, public API compatibility, or migration ordering.
- Verification: the exact existing commands for tests, linting, type checking, and builds.
- Protected areas: generated files, secrets, vendored code, lockfiles, infrastructure, or production migrations.
- Change boundaries: whether the agent may add dependencies, alter schemas, or modify public interfaces.
Do not begin by choosing a model, theme, extension set, or keyboard shortcut. That is tutorial theater. A real cursor setup succeeds or fails on whether the agent can distinguish an acceptable patch from a merely plausible one.
Repository instructions should also be committed with the code, not trapped in one engineer’s global preferences. Cursor’s official documentation explains the product’s controls, but your repository still has to provide its own definition of correctness.
If those repository facts are not yet explicit, start with PairFoundry’s free foundations track. Installing the tool before resolving them only makes ambiguity execute faster.
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The steps#
Use the following order because each step removes a specific failure mode before the agent can turn it into code. The installation itself is the least important part. A durable setup is a chain of constraints: repository truth, scoped context, explicit permissions, deterministic verification, and reviewable changes.
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Record the working tree state — this prevents pre-existing edits from being mistaken for agent output.
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Locate the repository’s canonical commands — this prevents the agent from inventing test, build, or formatting workflows that do not match CI.
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Write repository-scoped instructions — this prevents personal chat context from becoming an undocumented dependency.
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Exclude irrelevant and sensitive paths — this prevents generated output, credentials, caches, and large artifacts from polluting context.
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Define protected changes — this prevents casual dependency, schema, deployment, and public API edits.
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Require a plan before edits — this prevents the first plausible interpretation from becoming the implementation.
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Require narrow patches — this prevents opportunistic cleanup from hiding the change you actually requested.
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Run the smallest relevant verification first — this prevents slow full-suite feedback from obscuring a local mistake.
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Run repository-required checks before completion — this prevents “the code looks right” from replacing executable evidence.
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Review the diff, not the chat — this prevents a confident explanation from being treated as proof.
These controls are not Cursor-specific. Claude Code’s official documentation describes another agent surface, but the same repository contract should govern both. If switching tools changes what “done” means, the setup is too dependent on the tool.
For a ready-made operating structure, use the Agent Operating Kit. The point is not more prompting; it is a repeatable boundary between instructions, execution, verification, and human review. PairFoundry’s other packs are listed in the packs overview.
A working configuration#
Commit one concise repository rule and keep editor preferences separate. The rule below is deliberately boring: it tells Cursor where truth lives, what it must not change casually, and what evidence completion requires. Replace bracketed placeholders with commands and paths that already exist in your repository.
Create .cursor/rules/repository.mdc:
---
description: Repository operating contract
alwaysApply: true
---
<!-- Apply this rule to every agent task in this repository. -->
# Repository operating contract
<!-- Force repository evidence to outrank generic model assumptions. -->
Treat repository code, documentation, configuration, and tests as authoritative.
<!-- Stop the agent from editing before it understands the requested boundary. -->
Before editing, state the requested outcome, affected area, and verification plan.
<!-- Prevent invented commands from becoming part of the workflow. -->
Use only commands already defined in repository documentation, scripts, or CI.
<!-- Make the existing verification entry points explicit. -->
Relevant test command: `[existing test command]`
Relevant lint command: `[existing lint command]`
Relevant type-check command: `[existing type-check command]`
Relevant build command: `[existing build command]`
<!-- Preserve behavior that the repository cannot safely negotiate away. -->
Maintain these invariants:
- `[invariant one]`
- `[invariant two]`
- `[invariant three]`
<!-- Put high-consequence changes behind an explicit request. -->
Do not add dependencies, change schemas, modify public APIs, or edit deployment
configuration unless the task explicitly requires it.
<!-- Keep generated or externally owned material out of ordinary patches. -->
Do not edit generated, vendored, or lock files unless the required source change
necessarily regenerates them.
<!-- Prevent broad refactoring from riding along with a narrow task. -->
Keep the patch scoped; do not perform unrelated cleanup or formatting.
<!-- Require inspection of local conventions before creating new structure. -->
Follow nearby naming, error-handling, testing, and file-organization patterns.
<!-- Make uncertainty visible instead of resolving it through invention. -->
If repository evidence conflicts or a required fact is missing, stop and report
the exact ambiguity.
<!-- Define completion through evidence rather than confidence. -->
Before completion, run the smallest relevant check, then all repository-required
checks affected by the change.
<!-- Make the handoff reviewable without replaying the conversation. -->
Report changed files, behavior changed, checks run, and any remaining risk.Cursor documents its supported rule and configuration mechanisms in the official Cursor docs. Use the currently documented repository-scoped mechanism; do not copy a filename from an old tutorial and assume the product still interprets it.
The bracketed entries are intentionally not prefilled. Inventing commands would make this configuration look complete while making it operationally false. Repository-local truth is the configuration.
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What to skip#
Skip any setup step that adds ceremony without improving context, authority, verification, or review. Most cursor setup tutorials optimize the first five minutes: install extensions, select a model, paste a giant prompt, and generate code. That sequence produces motion, not a dependable engineering workflow.
| Common tutorial step | Why to skip it | |---|---| | Installing a large extension bundle | It increases variables before you know which capability is missing. | | Copying a universal rules file | Generic rules cannot encode your repository’s actual invariants. | | Indexing everything indiscriminately | More context can include generated files, stale docs, secrets, and irrelevant artifacts. | | Granting broad command approval immediately | Convenience is not a reason to erase execution boundaries. | | Asking the agent to “improve the codebase” | The task has no testable scope or stopping condition. | | Running the full suite after every edit | Start with the smallest relevant check, then expand before completion. | | Accepting a generated test as proof | A test can encode the same misunderstanding as the implementation. | | Tuning prompts before inspecting failures | Prompt changes without a concrete failure mode are superstition. |
Also skip duplicated policy across global settings, chat prompts, and repository files. Put durable repository constraints in the repository; keep personal interface preferences global.
The distinction follows directly from the mechanism: a large language model generates from the context it receives. Contradictory or irrelevant instructions do not become harmless because they are plentiful. For more setup guidance organized around repository operation, use PairFoundry’s agent setup hub.
First real task#
Make the first task a small, already-understood defect with an existing reproduction and a clear verification path. Do not start with architecture, a dependency migration, or a new subsystem. The objective is to validate the setup’s control loop, not to demonstrate how much code Cursor can generate.
Choose a task with:
- One observable incorrect behavior.
- A narrow likely ownership area.
- No required dependency or schema change.
- An existing test location or reproducible command.
- A diff a reviewer can understand without a design document.
Use this task statement:
Investigate this defect without editing first.
Expected behavior: [observable expected behavior]
Current behavior: [observable current behavior]
Reproduction: [existing command or steps]
Identify the likely cause, the repository evidence supporting it, the smallest
safe change, and the checks you will run. Wait for approval before editing.
After approval, keep the patch scoped and report the final diff and check results.The first success criterion is not “Cursor fixed it.” It is that Cursor respected the pause, used repository evidence, proposed a bounded patch, ran the specified checks, and produced a reviewable handoff. That behavior transfers across agent tools, including the workflows described in the Claude Code documentation.
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Related reading#
- Vibe coding tutorial: the order matters more than the settings
- GitHub Copilot CLI install in fifteen minutes, and what to skip
FAQ#
How to do Cursor setup?#
Start with repository invariants and existing verification commands. Then install Cursor, commit a repository-scoped operating rule, exclude irrelevant or sensitive paths, and test the workflow on a small known defect. Model selection and editor customization come later because neither defines what an acceptable patch is.
How to use Cursor for the first time?#
Open a real repository and ask Cursor to investigate a narrow defect without editing. Require it to identify evidence, propose the smallest change, and name the checks it would run. Approve edits only after reviewing that plan, then inspect the resulting diff and executable verification.
How do I set the Cursor back to normal?#
Reverse the smallest relevant customization first: disable the repository rule, remove task-specific context, or restore the editor preference you changed. Do not delete every setting blindly. Separate repository instructions from personal editor settings so one can be reset without destroying the other.
How to set Cursor settings?#
Use global settings for personal interface preferences and repository-scoped rules for shared engineering constraints. Keep durable rules short, committed, and tied to actual commands and invariants. Follow the supported configuration mechanism in the Cursor documentation, and avoid stale tutorial filenames or copied universal configurations.