---
okf: "0.1"
type: service
visibility: private
status: active
updated: 2026-08-06
links:
  - job-mail-imap-sync.md
  - job-mail-body-ingest.md
  - job-gmail-bulk-import.md
---

# kb-mail

Shared library for the mail pillar. Everything that more than one mail job needs lives here,
by rule rather than by taste: the corpus rests on 225 030 envelopes whose ids, archive paths
and header entities were produced by one implementation, and a second copy of any of those
derivations would silently stop agreeing with the first.

**Kod:** `packages/kb-mail/` (`src/kb_mail/`, `pyproject.toml`, `tests/`)

Dependencies: `asyncpg`, `structlog`. Nothing else — the IMAP transport is stdlib `imaplib`.

## Modules

| Module | What it holds | Used by |
|---|---|---|
| `envelope` | The frozen cross-source `Envelope` dataclass (mirrors `envelope` in kb-postgres). Additive contract. | everything |
| `db` | asyncpg helpers: `insert_envelope` (returns the command tag), `get_envelope`, `rows_affected`, `envelope_source` | all jobs |
| `archive` | `save_eml` — append-only `.eml` writer, `{root}/{source}/{YYYY}/{MM}/{id}.eml`. `FileExistsError` is the "already have it" signal, never masked. | bulk-import, imap-sync |
| `text` | `sanitize_surrogates`, `strip_nul` — both mandatory before anything reaches `text`/`jsonb` | all parsing paths |
| `chunking` | `chunk_text` (2400/600 chars), extracted in Krok 0 | mail-body-ingest, documents-ingest |
| `headers` | `parse_headers`, `parse_headers_fallback`, `parse_headers_resilient` — the `entities[type=headers]` shape, typed parse with a compat32 fallback | header-backfill, imap-sync |
| `message` | `message_id`, `parse_date`, `parse_attachments`, `eml_ref`, `EPOCH` — envelope id, timestamp, attachment manifest, archive path | bulk-import, imap-sync |
| `imap` | `ImapAccount`, `ImapClient`, `FolderStatus` — read-only IMAP over stdlib `imaplib` | imap-sync |
| `sync_state` | `mail_sync_state` accessors + `plan_folder_sync` / `contiguous_last_uid` | imap-sync |

`headers` and `message` were extracted from `gmail-header-backfill` and `gmail-bulk-import`
respectively when `mail-imap-sync` needed the same derivations (2026-08-06). Both jobs
re-export them under their original names, so their CLIs and test suites are unchanged. This
is the same move as `chunking` in Krok 0 — extract, do not copy.

## Why the IMAP transport lives here and not in the job

The adapter is protocol code, and the sync-cursor semantics (UIDVALIDITY invalidation, how far
a cursor may advance) are protocol semantics — both are worth testing in isolation, and both
would otherwise be buried in a job's loop where a wrong branch is invisible. `kb_mail.imap` and
`kb_mail.sync_state` therefore carry the rules; `jobs/mail-imap-sync` carries the orchestration
and the policy. See `kb/services/job-mail-imap-sync.md` for the behaviour they add up to.

## Tests

```bash
pip install -e "packages/kb-mail[dev]"
cd packages/kb-mail && pytest
```

111 unit tests, no DB or network. `tests/test_db.py` is additionally marked `integration` and
needs a live kb-postgres (`KB_TEST_DSN`, default `localhost:5433`) — it is the only file that
does, and it errors rather than skips when the DB is absent.