docs(all): add AGENTS.md and update development guide

AGENTS.md

@@ -0,0 +1,87 @@
+# AGENTS.md
+
+Instructions for coding agents. Setup, workflow, commit scopes and releases are in [docs/development.md](docs/development.md).
+
+## Done condition
+
+Set up per [Requirements](docs/development.md#requirements). A change is done when this exits 0 (~30 s from a cold cache):
+
+```console
+yarn compile && yarn lint && yarn test
+```
+
+For one package, run `yarn test` from `packages/<pkg>` (core takes ~1 s). `yarn lint` prints react-native parse warnings; the exit code is the signal.
+
+## Where things live
+
+- `expect()` dispatch: `packages/core/src/lib/expect.ts`.
+- Plugins: `usePlugin()` in `packages/core/src/main.ts` registers them into `packages/core/src/lib/config/Config.ts`, which `expect()` consults.
+- One `*Assertion.ts` per type, in `packages/<pkg>/src/lib/`. Tests live in each package's `test/`.
+
+## Matcher pattern
+
+Build both errors, then pass them to `this.execute`, which handles `.not`. Copy `toBeGreaterThan` in `packages/core/src/lib/NumberAssertion.ts`:
+
+```ts
+/**
+ * Check if the number value is greater than the defined value.
+ *
+ * @example
+ * ```
+ * expect(5).toBeGreaterThan(3);
+ * ```
+ *
+ * @param value the value that number should be greater than
+ * @returns the assertion instance
+ */
+public toBeGreaterThan(value: number): this {
+  const error = new AssertionError({
+    actual: this.actual,
+    message: `Expected <${this.actual}> to be greater than <${value}>`,
+  });
+  const invertedError = new AssertionError({
+    actual: this.actual,
+    message: `Expected <${this.actual}> NOT to be greater than <${value}>`,
+  });
+
+  return this.execute({
+    assertWhen: this.actual > value,
+    error,
+    invertedError,
+  });
+}
+```
+
+Each test case asserts the direct and the `.not` path with exact messages (`packages/core/test/lib/NumberAssertion.test.ts`):
+
+```ts
+// actual 3: passes directly, throws under .not
+assert.deepStrictEqual(test.toBeGreaterThan(2), test);
+assert.throws(() => test.not.toBeGreaterThan(2), {
+  message: "Expected <3> NOT to be greater than <2>",
+  name: AssertionError.name,
+});
+
+// actual 1: throws directly, passes under .not
+assert.throws(() => test.toBeGreaterThan(2), {
+  message: "Expected <1> to be greater than <2>",
+  name: AssertionError.name,
+});
+assert.deepStrictEqual(test.not.toBeGreaterThan(2), test);
+```
+
+## Test rule
+
+Give every comparison matcher an equal-value/boundary case and a negative-number case. JS `%` keeps the sign of the left operand, and the suite once let a `>` → `>=` mutation pass.
+
+## Pull requests
+
+The repo is squash-merge only: the PR title becomes the commit message and drives semantic-release. Write it as a Conventional Commit with a scope from [Scopes](docs/development.md#scopes).
+
+## Dependency fixes
+
+Add a `resolutions` entry in the root `package.json`, run `yarn dedupe`, then verify with `yarn why <pkg>` and `yarn npm audit --all --recursive --severity high` (the fixed package must no longer appear in the report; exit 0 means no findings at all).
+
+## Release boundary
+
+Only maintainers release, through `.github/workflows/release.yml`. Leave that workflow, `.yarn/releases/`, `yarn release` and `npm publish` alone.

docs/development.md

@@ -1,17 +1,18 @@
 # Development
 
-To setup your local environment follow the next steps.
+To setup your local environment follow the next steps. [AGENTS.md](../AGENTS.md) is the instruction file for coding agents.
 
 ## Requirements
 
-* Latest [Yarn Classic](https://classic.yarnpkg.com)
-* NodeJS (Use version set on [.nvmrc](https://github.com/stackbuilders/assertive-ts/blob/master/.nvmrc))
+* NodeJS (Use version set on [.nvmrc](https://github.com/stackbuilders/assertive-ts/blob/main/.nvmrc))
+* [Corepack](https://yarnpkg.com/corepack), which provides the Yarn 4 version pinned in `package.json`. Run `corepack enable` once. NodeJS 25 and later no longer bundle it, so run `npm install -g corepack` first.
 
 ## Useful commands
 
 ### Install dependencies
 
 ```console
+corepack enable
 yarn install
 ```
 
@@ -39,10 +40,12 @@ The release process is automated by [semantic-release](https://semantic-release.
 
 ### Scopes
 
-Scopes are optional on Conventional Commits, but we take advantange of them to specify the package a change is aimed for. The table below describes the available scopes and what package they affect:
+Scopes are optional on Conventional Commits, but we take advantage of them to specify the package a change is aimed for. The table below describes the available scopes and what package they affect:
 
-| Scope   | Package               | Commit example                   |
-| :-----: | :-------------------: | -------------------------------- |
-| `all`   | All packages          | feat(all): Upadate TypeScript    |
-| `core`  | `@assertive-ts/core`  | fix(core): Boolean assertion bug |
-| `sinon` | `@assertive-ts/sinon` | fix(sinon): Spy assertion bug    |
+| Scope    | Package                | Commit example                     |
+| :------: | :--------------------: | ---------------------------------- |
+| `all`    | All packages           | feat(all): Update TypeScript      |
+| `core`   | `@assertive-ts/core`   | fix(core): Boolean assertion bug   |
+| `dom`    | `@assertive-ts/dom`    | fix(dom): Element assertion bug    |
+| `native` | `@assertive-ts/native` | fix(native): Element assertion bug |
+| `sinon`  | `@assertive-ts/sinon`  | fix(sinon): Spy assertion bug      |