Mail-source adapter — mbox / local archive (stub)

Reference adapter for a static mbox (or Maildir, or a directory of .eml files) as a read-only backend for the security-issue-import family of skills. Stub status — this document describes the contract; the concrete CLI wiring lands when an adopter actually wires a local archive in.

See ../contract.md for the abstract mail-source-backend operations + capability matrix + adopter resolution rules this adapter conforms to.

The concrete vendor home for this local-files backend is tools/maildir/ (Vendor: Maildir). That tool pairs this inbound read side with a fully-implemented outbound side — it files editable drafts into a local Maildir for the contract:mail-create capability — so one offline, credential-free vendor covers both mail directions, the way tools/gmail does for Google.

When this adapter makes sense

Forensics / late triage of a historical security thread. The inbox is gone or the role mailbox is no longer credentialed, but the messages were archived to an mbox snapshot at the time. The skill can still classify, extract template fields, and reconcile against trackers — it just can't draft a reply.
Air-gapped triage environments. The agent runs offline against a thumbdrive snapshot of <security-list> for the time window being audited.
Compliance / discovery exports. A regulator request produces an mbox export of all <security-list> mail for a time range; the skill imports it the same way it would import live mail, into a scratch tracker repo, without touching any live mail credentials.

Capability claim

Operation	Supported?	Notes
`list_recent_threads(list, since)`	✓ (offline)	Parse the mbox, group messages by `References:` / `In-Reply-To:` chain, filter by message `Date:` newer than `since`. The `list` parameter is advisory — the mbox is whatever the operator pointed the adapter at, no remote subscription is checked
`read_thread(thread_id)`	✓	Same parser; return all messages in the thread
`list_drafts(thread_id)`	✗	A static archive has no concept of pending drafts
`list_sent_since(thread_id, since)`	✗ (or limited)	Only if the archive includes the team‘s outbound mail (some exports do; many don’t). The adapter declares this op as `unsupported` by default; an adopter with an outbound-included archive may upgrade the claim per-deployment
`create_draft(thread_id, body, …)`	✗	Read-only by construction
`thread_url(thread_id)`	depends	If the project has a public archive (PonyMail, Pipermail), construct the URL from the thread root‘s Message-ID. Otherwise return `file://<archive-path>#<message-id>` which only works in the operator’s local environment
`thread_id_kind`	`rfc5322-message-id`	Same as IMAP — root Message-ID is the stable identifier

Auth + setup

There is no auth — the archive file is a file. The adopter declares:

Archive path — absolute path to the mbox file, or to the Maildir/ root, or to a directory of .eml files. The adapter sniffs format from the path shape.
Time window cap — optional safety knob to refuse parsing archives larger than N MB unless explicitly approved. Prevents accidental long-running parses of multi-year archives.
Read-only enforcement — the adapter MUST NOT write to the archive path under any circumstance. The framework's privacy-LLM gate (see ../../privacy-llm/) should also be considered before sending archive content to any LLM consumer.

What an adopter declares in `project.md`

## Mail sources

| Backend | Role | Mandatory | Notes |
|---|---|---|---|
| `mbox` | primary | yes | Forensics-only deployment; archive at `/srv/audit/security-list-2024.mbox` |

…or as a fallback for an otherwise-live deployment:

| `gmail` | primary  | yes | Triager Gmail subscribed to `<security-list>` |
| `mbox`  | fallback | no  | 2024-Q4 snapshot at `/srv/snapshots/security-list-2024-Q4.mbox`; used when Gmail history is incomplete |

Why this is a stub

No adopter is currently using it. The stub documents the contract shape so a forensics / compliance team can wire the adapter without re-designing the read interface; concrete parsing code lands alongside this README when the first such adopter materialises.