chore: sync to node-red-standards v0.3.3 (AGENTS block + .gitattributes)

.gitattributes

@@ -0,0 +1,11 @@
+# Normalise line endings in the *working tree*, not just in the index.
+#
+# Prettier's `endOfLine` defaults to "lf" and this standard's .prettierrc.json does not override
+# it, so a file checked out as CRLF fails `npm run format:check` even when the blob stored in git
+# is LF. With core.autocrlf=true -- the Windows default -- that happens to every file a checkout
+# or pull touches, which turns format:check red locally while CI stays green on Linux. Pinning
+# the working tree to LF makes local and CI results identical on every platform.
+* text=auto eol=lf
+
+# Hooks are executed by sh; CRLF would break them outright.
+.husky/* text eol=lf

AGENTS.md

@@ -7,37 +7,67 @@
 > below the managed block (the "Project-specific rules" section) is yours and is never overwritten.
 
 ## Shared: Architecture
+
 - Node packages are modular: `lib/` holds framework-independent, unit-testable core logic;
   `nodes/` holds one file per Node-RED node; `icons/` holds node icons.
 - The registered entry file (`<pkg>/99-<name>.js`) is a thin delegator that only `require`s and
   registers the modules in `nodes/`. Keep runtime glue thin.
 - Record non-trivial design decisions as an ADR in `doc/architecture/adr/`.
 
 ## Shared: Code style
-- Lint: ESLint flat config (`eslint.config.js`), ESLint >= 9. Run the lint script before committing.
+
+- Lint: ESLint flat config (`eslint.config.js`), ESLint >= 10. Run the lint script before committing.
+  `eslint` and `@eslint/js` must stay on the same major: `@eslint/js@10` peers on `eslint@^10`, and
+  pairing `eslint@10` with `@eslint/js@9` silently keeps the v9 recommended rule set.
+- ESLint 10's recommended set adds `no-unassigned-vars` and `no-useless-assignment`. Both are errors:
+  don't declare a binding only to pass `undefined` around, and don't assign a value no later
+  statement reads.
 - Format: Prettier (`.prettierrc.json`) — 4-space indent, single quotes, es5 trailing commas.
 - Target Node.js >= 20.
 - Avoid `var` — use `const`, or `let` only when the binding is reassigned (enforced by `no-var` / `prefer-const`).
 - One statement per line — don't pack multiple instructions onto a single line; keep lines simple to read (enforced by `max-statements-per-line`).
-- Single exit — each function has exactly one `return`, placed as its final statement; avoid early or multiple returns.
+- Keep functions short, with a single exit:
+    - **One exit per function.** A function leaves in exactly one place: its last statement. This
+      includes guard clauses — an early `return` in a precondition check is still a second exit and is
+      not allowed. Assign to a single result and return it as the last statement. `throw` is the one
+      permitted exception, because it is not a return and a `finally` still runs.
+    - **Validate by nesting, not by leaving.** State the precondition as the condition that must hold
+      and put the work inside it, with the error path in the `else`. Where the caller is code, `throw`
+      instead; where the caller is a Node-RED flow, the `else` calls the error path.
+    - **Keep functions short enough that the nesting does not matter.** The objection to nesting is
+      really an objection to long functions — at a readable length, one or two levels of indentation
+      cost nothing. If the nesting starts to hurt, extract a function; never add a second exit.
+    - **Most likely case first within each branch**, so a reader meets what the function normally does
+      before the exceptions.
+    - **If every path must do trailing work, put that work in `finally`** rather than repeating it
+      before each exit — combined with the single exit this makes the epilogue unskippable.
+- No defensive programming. Do not check for states that cannot occur, and do not guard against
+  hypothetical future changes to code you control. Validate input at the boundary and then trust it.
 
 ## Shared: Tests
+
 - Node's built-in test runner (`node --test`) + `node-red-node-test-helper`. Tests live in `test/` as `*.test.js`.
   Import `{ describe, it }` from `node:test` and assert with `node:assert`. Coverage via `c8`.
+- Node's default discovery runs **every** `.js` under `test/`, whatever it is named, so shared helpers and
+  fixtures belong outside that directory (e.g. `test-helpers/`). The test script deliberately takes no path
+  arguments: a `'test/**/*.test.js'` glob would need Node >= 21 and fails on Node 20, which is still supported.
 
 ## Shared: Documentation
+
 - `README.md` is user-facing. Architecture docs live under `doc/architecture/`
   (`overview.md`, `structural-design.md`, `behavioural-design.md`, `adr/`).
 - Update `CHANGELOG.md` (Keep a Changelog style) for every user-visible change; bump the
   patch version in `package.json` in the same commit.
 
 ## Shared: Workflow
+
 - CI (`.github/workflows/node.js.yml`) must pass: lint, format:check, test, coverage.
 - Releases go through `.github/workflows/npm-publish.yml`.
 - Never bump the major version without an ADR explaining the breaking change.
 
 ## Shared: package.json scripts
-`lint`, `lint:fix`, `format`, `format:check`, `test` (`node --test`), `coverage` (`c8 node --test`), `coverage:check`.
+
+`lint`, `lint:fix`, `format`, `format:check`, `test` (`node --test` with `--test-force-exit --test-timeout=30000 --test-concurrency=1`, no path args), `coverage` / `coverage:check` (c8 over `npm test`).
 
 <!-- END node-red-standards:managed -->