# Tasks: enterprise-email-processing

**Change ID**: enterprise-email-processing
**Package**: `@suaveplan/email-processing`
**Target path**: `universal/email/email-processing`
**Prerequisite packages on Verdaccio**: `@suaveplan/error`, `@suaveplan/types`, `@suaveplan/validation`

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## 0. Pre-flight (non-negotiable)

- [ ] 0.1 Confirm clean working tree (`git status` reports nothing) and no in-flight worktrees with uncommitted work (`git worktree list` then `git status` in each)
- [ ] 0.2 If any worktrees exist under `.claude/worktrees/`, account for each one: still-active agent, work-pending-merge, or stale-and-prune. Stale worktrees MUST be removed (`git worktree remove`) before opening a new one — code that has been lost twice on main is the failure mode this guards against.
- [ ] 0.3 Confirm the package set in `MANIFEST.md` matches `find packages -maxdepth 3 -name package.json` count. Drift here means a prior change archived without regenerating the manifest.

## 1. Scaffold

- [ ] Create `universal/email/email-processing/` with `src/`, `tests/`, `src/__benchmarks__/` and all feature subdirectories per the layout in `proposal.md`.
- [ ] Write `package.json` at version `0.1.0` with `"type": "module"`, `"sideEffects": false`, correct `exports` map (one subpath per feature module), `dependencies`, and `devDependencies`.
- [ ] Write `tsconfig.json` extending `@suaveplan/typescript-config/library.json`.
- [ ] Write `vitest.config.ts` using `createTestConfig()` from `@suaveplan/testing/config`.
- [ ] Add `lint`, `typecheck`, `test`, `test:coverage`, `build`, `docs:check` scripts.

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## 2. Types + errors

- [ ] `src/types/common.ts` — define `ParsedEmail`, `EmailAddress`, `Attachment`, `ParseOptions`, `HtmlToTextOptions`, `ValidateOptions`, `ValidationResult`, `EmailParseStream`, `EmailParseEvent`.
- [ ] `src/types/common.md` (≥200 words, both examples, API reference).
- [ ] `src/error-codes.ts` — define `EmailProcessingErrorCode` union (6 codes), `EMAIL_PROC_ERROR_METADATA`, `registerEmailProcessingErrorCodes()`, eager call at bottom.
- [ ] `src/types/schemas.ts` — Zod schemas for all public option types and parsed output shapes; `src/types/schemas.md`.

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## 3. Core modules

- [ ] **`src/core/header-parser/`** — `parseHeaders(raw)`: fold/unfold RFC 5322 header lines, return `Map<string, string[]>`. Tests: fold/unfold round-trip, multi-value headers, encoded-word (RFC 2047) decoding.
- [ ] **`src/core/address-parser/`** — `parseAddressList(value)`: RFC 5321/5322 grammar, display names with quotes, group syntax, angle-bracket addresses. Tests: bare address, display-name, group, nested comments, encoded display names.
- [ ] **`src/core/mime-decoder/`** — multipart boundary splitting, Base64 and Quoted-Printable decoding, Content-Transfer-Encoding dispatch, charset decoding via `TextDecoder`. Tests: multipart/mixed, multipart/alternative, nested multipart, binary attachment, QP line wrapping.
- [ ] **`src/core/parser/`** — `parseEmail(raw, options)`: orchestrates header-parser → MIME decoder → body extraction → attachment enumeration. Tests: simple text-only, text+HTML, with attachment, multiple attachments, oversized message (throws `EMAIL_PROC_TOO_LARGE`), AbortSignal abort.
- [ ] **`src/validation/address-validator/`** — `validateAddress(address, options)`: syntax check (regex), optional disposable-domain lookup (bundled JSON list), result typed. Tests: valid, invalid syntax, disposable domain, `checkDisposable:false` skips list.
- [ ] **`src/extraction/html-to-text/`** — `htmlToText(html, options)`: strip tags, decode HTML entities, preserve paragraph breaks, handle `<a href>` link text. Tests: plain paragraph, link, table, nested elements.
- [ ] **`src/streaming/email-stream/`** — `createEmailStream(options)`: Web Streams Transform; emits `headers`, `textBody`, `htmlBody`, `attachment` events. Tests: pipe a 3-part message, verify events emitted in order, abort mid-stream.

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## 4. OTel instrumentation

- [ ] Obtain tracer + meter at module scope (`trace.getTracer('email-processing')`).
- [ ] `parseEmail`: span `email.parse`, attributes `email.attachment_count`; counter `email.parse_total`; histogram `email.parse_duration_ms`.
- [ ] `validateAddress`: counter `email.validate_total` with attribute `email.valid`.

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## 5. Property-based tests (`tests/property.test.ts`)

- [ ] Header fold/unfold round-trip: folded line reassembles to original for arbitrary ASCII header values ≤998 chars.
- [ ] Address list round-trip: `parseAddressList(formatAddressList(list)) ≡ list` for arbitrary arrays of `EmailAddress`.
- [ ] HTML-to-text idempotency: `htmlToText(htmlToText(html)) ≡ htmlToText(html)` when input is already plain text (no tags).

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## 6. Benchmarks (`src/__benchmarks__/email-processing.bench.ts`)

- [ ] Parse a 50 KB multipart/mixed message with 2 attachments (cold path).
- [ ] `parseHeaders` only on same message (fast path).
- [ ] `parseAddressList` on a 50-address list.

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## 7. Docs

- [ ] One `.md` per implementation file (≥200 words, both simple + advanced examples, API reference).
- [ ] Root `README.md` with purpose, install, quick-start, module table, dependencies.

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## 8. Verify and publish

- [ ] `bunx turbo lint typecheck test --filter=@suaveplan/email-processing` — green.
- [ ] `bunx turbo test:coverage --filter=@suaveplan/email-processing` — 100% statements/branches/functions/lines.
- [ ] `bun run docs:check --filter=@suaveplan/email-processing` — zero errors.
- [ ] No `TODO`, `FIXME`, `any`, `.skip` in `src/` or `tests/`.
- [ ] `"sideEffects": false` set.
- [ ] `bun scripts/publish.ts --package @suaveplan/email-processing`.
- [ ] Archive: `openspec/archive/2026-04-24-enterprise-email-processing/`.