# AGENTS.md This document is for AI agents only. Follow it strictly. ## Non-Negotiable Rules - Do not change the public API unless explicitly requested. - Do not add new public functions. - Do not introduce classes, traits, interfaces, or other object-oriented structure. - Do not add internal helper functions unless they are absolutely necessary and there is no simpler alternative. - Do not rename existing functions for style reasons. - Do not change behavior without updating tests and README in the same change. - Do not change PHP compatibility without explicit instruction. ## Project Contract - `array_flatten()` is the only intended public function. - The function must preserve first-seen order. - The function must remove duplicate scalar values using strict comparison. - The package must remain compatible with PHP `^8.0.2`. ## Documentation Rules - Keep `README.md` aligned with runtime behavior. - Keep the README concise, technical, and factual. - If behavior changes, update the README and tests together. - Do not add marketing language or unnecessary narrative. ## Testing Rules - Every behavior change must be covered by tests. - Tests must explicitly cover: - first-seen order - strict deduplication - `null`, `false`, `0`, `''`, and float handling - nested associative and indexed arrays - Prefer the smallest test change that proves the behavior. ## Editing Rules - Make the smallest possible change that solves the task. - Preserve existing formatting unless a formatter is being run. - Prefer direct code over abstraction. - Avoid introducing new dependencies. - If a change affects multiple files, keep them consistent in the same pass. ## Verification Rules - Run PHPUnit after code changes. - Run syntax checks when PHP files are edited. - Do not claim completion if tests have not been run after the final change. ## Conflict Rule - If a user request conflicts with this document, follow the user request. - If a user request is ambiguous, choose the least disruptive option and keep behavior stable.

AGENTS.md

This document is for AI agents only. Follow it strictly.

Non-Negotiable Rules

Do not change the public API unless explicitly requested.
Do not add new public functions.
Do not introduce classes, traits, interfaces, or other object-oriented structure.
Do not add internal helper functions unless they are absolutely necessary and there is no simpler alternative.
Do not rename existing functions for style reasons.
Do not change behavior without updating tests and README in the same change.
Do not change PHP compatibility without explicit instruction.

Project Contract

array_flatten() is the only intended public function.
The function must preserve first-seen order.
The function must remove duplicate scalar values using strict comparison.
The package must remain compatible with PHP ^8.0.2.

Documentation Rules

Keep README.md aligned with runtime behavior.
Keep the README concise, technical, and factual.
If behavior changes, update the README and tests together.
Do not add marketing language or unnecessary narrative.

Testing Rules

Every behavior change must be covered by tests.
Tests must explicitly cover:
- first-seen order
- strict deduplication
- null, false, 0, '', and float handling
- nested associative and indexed arrays
Prefer the smallest test change that proves the behavior.

Editing Rules

Make the smallest possible change that solves the task.
Preserve existing formatting unless a formatter is being run.
Prefer direct code over abstraction.
Avoid introducing new dependencies.
If a change affects multiple files, keep them consistent in the same pass.

Verification Rules

Run PHPUnit after code changes.
Run syntax checks when PHP files are edited.
Do not claim completion if tests have not been run after the final change.

Conflict Rule

If a user request conflicts with this document, follow the user request.
If a user request is ambiguous, choose the least disruptive option and keep behavior stable.