Module attachments 

Attachments table operations.

Attachments are normalized into one row per attachment (see migration 74), keyed to their event (ON DELETE CASCADE) and indexed by content hash. This module is the single source of truth for attachment persistence; the legacy ["attachments", …] tag in events.tags is left in place on pre-migration events as an untouched safety net but is never read.

Functions

backfill_downloaded_by_hash

Mark every OTHER attachment sharing this content hash as downloaded to the same path — the download-sharing dedup, now an indexed WHERE hash = ? instead of a LIKE '%hash%' table scan. Returns the affected event ids so the caller can reconcile in-memory STATE.

clear_attachment_download

Mark an attachment not-downloaded (its file went missing). Clears the path.

downloaded_attachment_paths

A downloaded attachment’s on-disk path, for the integrity sweep. Returns (event_id, hash, path) for every attachment claiming downloaded=1 with a non-empty path — an indexed read, no per-event JSON parse.

get_attachments_for_event

Attachments for a single event, ordered by att_index.

get_attachments_for_events

Attachments for a set of events, event_id → Vec<Attachment> ordered by att_index. Batched (one IN (…) query) for a message window, mirroring the reactions/edits loaders.

insert_attachment_rows

Upsert a message’s attachment rows onto the given connection or transaction, so save_message can commit them ATOMICALLY with the event row (an event + no attachments would render as a broken file message with no fallback). Upserts on (event_id, att_index). The mutable local state is handled so a re-save never regresses a completed download: downloaded is MONOTONIC (MAX(existing, incoming)), and hash/path only take the incoming values when the incoming carries a completed download (downloaded=1) — the nonce→content-hash rewrite the download path performs. So a relay re-delivery (downloaded=0) preserves the downloaded file, its content-hash key, and its path; a completed download persists all three in one pass. Explicit un-download goes through clear_attachment_download, never here.

rewrite_downloaded_paths

Repoint downloaded-file paths from old download directories to a new one (Android download-dir migration). For each downloaded attachment whose path starts with an old prefix: move it to new_dir/<filename> if that exists, else mark it not-downloaded. Returns the affected event ids.

set_attachment_downloaded

Flip one attachment’s downloaded state — a single-row UPDATE keyed by (event_id, content hash), replacing the old read-modify-write of the whole tags blob.