mailer v1: the transport layer ported from upyo 0.7.0, with 71 upstream bugs fixed

.claude/skills/js-conventions/SKILL.md

@@ -4,7 +4,8 @@ description: Apply the Alexis JavaScript style (Metarhia-derived, linted by oxli
 ---
 
 <!-- Adapted from metaskills v1.0.5 (skills/js-conventions) for the Alexis toolchain:
-     oxlint + oxfmt instead of ESLint + Prettier, pnpm instead of npm, 100 columns instead of 80. -->
+     oxlint + oxfmt instead of ESLint + Prettier, pnpm instead of npm, 100 columns instead of 80;
+     loops in one pass instead of array iteration methods in library code (src/). -->
 
 # JavaScript Code Style
 
@@ -58,15 +59,18 @@ Use following conventions for JavaScript and TypeScript code.
 - Do not mutate input parameters; avoid `arguments`
 - Keep functions small and single-purpose
 - Decompose long expressions into intermediate variables
-- Prefer explicit loops (`for`, `for..of`) in hot paths
-- Use array methods when they improve readability
+- Iterate with `for` and `for..of` loops in library code (`src/`), index loops in hot paths; no
+  array iteration methods there (`.map`, `.filter`, `.some`, `.every`, `.find`, `.findIndex`,
+  `.findLast`, `.reduce`, `.flatMap`, `.forEach`), cold paths included
+- Compute everything a collection gives in one pass with an early exit; never chain passes
+  (`.map().join()`, `Object.entries().filter()`, `Array.from().map()`), and do not build an array
+  only to iterate it (spread of an iterable, `Array.from(string)`, `split` only to test)
 - Use `===` and `!==` only
 - Keep return types consistent
 - Avoid nested ternaries and deep callback nesting
 - Self-documented and self-descriptive code: do not add
   obvious comments, code should be clear without comments
-- Use iteration methods like `.map`, `.filter`, `.reduce` if it is good for code semantic
-- Try to avoid `.forEach` if callback operates with outer context
+- Tests, scripts and benchmarks may use array iteration methods where they read better
 
 ## Optimizations
 
@@ -86,6 +90,10 @@ Use following conventions for JavaScript and TypeScript code.
 - Move reusable callbacks outside loops
 - Keep `try/catch`, spread/rest away from hot loops
 - Use `Map` for dynamic key dictionaries, plain objects for fixed schemas
+- Build a lookup once: a module-level `Set` for membership, a `Map` for keyed search, instead of
+  repeated linear scans (`.includes`, a `.find` per call)
+- Keep caches and metadata on objects you do not own (a message, a config) in a `WeakMap` or
+  `WeakSet` rather than in a property on them
 - Use `Set` for big and dynamic collections, prefer arrays for short and stable
 - Use `Object.create(null)` for pure dictionaries
 - Use typed arrays for numeric and binary workloads

.claude/skills/npm-publish/SKILL.md

@@ -31,13 +31,14 @@ pnpm run lint                    # oxlint
 pnpm run format:check            # oxfmt
 pnpm run test:coverage           # tests under the c8 coverage gate
 pnpm run test:types              # tsd
-pnpm run check:dts               # tsc over index.d.ts
+pnpm run check:dts               # tsc over the d.ts of every entry of the exports map
+pnpm size --check                # the budgets of scripts/size-budgets.json
+pnpm run check:pack              # the tarball: every file of the exports map, nothing else
 ```
 
-These are the same gates `prepublishOnly` runs. CI adds three more; run them too:
+These are the same gates `prepublishOnly` runs. CI adds two more; run them too:
 
 ```bash
-pnpm size --max-gzip 4                                           # the bundle budget
 pnpm docs:comparison && git diff --exit-code docs/guide/comparison.md   # the table matches docs/comparison.json
 pnpm run docs:build                                              # the docs site; a dead link fails it
 ```
@@ -58,7 +59,7 @@ Compute the new version based on user intent and semver rules:
 - **prerelease**: `1.2.3` → `1.2.4-<label>.0`, or `1.2.4-beta.0` → `1.2.4-beta.1`
 - **Removing prerelease tag**: `4.0.3-prerelease` → `4.0.3` (just strip the suffix)
 
-Update `"version"` in `package.json` with the Edit tool, not `pnpm version`: the bump is a plain edit, and the commit, tag and changelog are handled by hand in the steps below.
+Update `"version"` in `package.json` with the Edit tool, not `pnpm version`: the bump is a plain edit, and the commit, tag and changelog are handled by hand in the steps below. Bump `version` in `src/version.js` to the same value (the OpenTelemetry instrumentation scope reads it; `tests/unit/version.test.js` fails while the two differ).
 
 ## Step 3: Update CHANGELOG.md
 
@@ -163,10 +164,12 @@ Check these fields are correct:
 
 ```bash
 pnpm pack --dry-run
+pnpm run check:pack
 pnpm run size
 ```
 
-Review the file list:
+`check:pack` fails on a file of the exports map missing from the tarball or a file outside the
+`files` allowlist; review the file list anyway:
 
 - Source files (`src/`) and root entry points are included
 - Type definitions are included
@@ -180,7 +183,7 @@ Report the file count and the bundle size from `pnpm run size` to the user.
 Run the gates one more time after all edits:
 
 ```bash
-pnpm run lint && pnpm run format:check && pnpm run test:coverage && pnpm run test:types && pnpm run check:dts && pnpm size --max-gzip 4 && pnpm run docs:build
+pnpm run lint && pnpm run format:check && pnpm run test:coverage && pnpm run test:types && pnpm run check:dts && pnpm size --check && pnpm run check:pack && pnpm run docs:build
 ```
 
 Must exit 0. If it fails, fix and re-run.

.gitattributes

@@ -0,0 +1,7 @@
+# LF everywhere, also on Windows checkouts: MIME output, DKIM canonicalization
+# and the SMTP dot-stuffing tests compare bytes.
+* text=auto eol=lf
+
+# Fixtures compared byte for byte are never converted.
+*.pem -text
+*.eml -text

.github/workflows/ci.yml

@@ -30,9 +30,13 @@ jobs:
       - run: pnpm install --frozen-lockfile
       - run: pnpm lint
       - run: pnpm format:check
-      # Smoke: keeps the bundle-size script working and fails over the
-      # min+gzip budget, which also catches a third-party module bundled in.
-      - run: pnpm size --max-gzip 4
+      # Fails over the min+gzip budget of an entry in scripts/size-budgets.json,
+      # which also catches a third-party module bundled in, and on an entry of
+      # the exports map without a budget.
+      - run: pnpm size --check
+      # The tarball holds every file of the exports map and nothing outside
+      # the files allowlist.
+      - run: pnpm run check:pack
 
   types:
     runs-on: ubuntu-latest

.oxlintrc.json

@@ -255,13 +255,99 @@
     "no-setter-return": "error",
     "no-unused-private-class-members": "error",
     "no-constant-binary-expression": "error",
-    "no-console": "error"
+    "no-console": "error",
+    "func-style": [
+      "error",
+      "expression"
+    ],
+    "no-nested-ternary": "error",
+    "max-depth": [
+      "error",
+      {
+        "max": 4
+      }
+    ]
   },
   "overrides": [
+    {
+      "files": [
+        "src/**"
+      ],
+      "plugins": [
+        "unicorn"
+      ],
+      "rules": {
+        "no-restricted-properties": [
+          "error",
+          {
+            "property": "map",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "filter",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "some",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "every",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "find",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "findIndex",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "findLast",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "findLastIndex",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "reduce",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "reduceRight",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "flatMap",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          },
+          {
+            "property": "forEach",
+            "message": "src/ iterates with loops in one pass (CLAUDE.md, Conventions)."
+          }
+        ],
+        "max-lines-per-function": [
+          "warn",
+          {
+            "max": 80,
+            "skipBlankLines": true,
+            "skipComments": true
+          }
+        ],
+        "unicorn/no-array-for-each": "error",
+        "unicorn/no-array-reduce": "error",
+        "unicorn/no-useless-spread": "error",
+        "unicorn/prefer-set-has": "error"
+      }
+    },
     {
       "files": [
         "scripts/**",
-        "bench/**"
+        "bench/**",
+        "tests/e2e/**",
+        "tests/helpers/**"
       ],
       "rules": {
         "no-console": "off"