Add iMessage sync support

[vanboompow]

Summary

• New sync-imessage command that reads macOS ~/Library/Messages/chat.db and imports messages into msgvault
• Implements gmail.API interface over SQLite chat.db for plug-and-play integration with existing sync infrastructure
• Uses existing SourceType field in sync.Options (added by IMAP support)

New files

• internal/imessage/client.go - gmail.API implementation over chat.db
• internal/imessage/parser.go - MIME builder, timestamp conversion
• internal/imessage/models.go - chat.db row types
• internal/imessage/parser_test.go - tests for parsing utilities
• cmd/msgvault/cmd/sync_imessage.go - CLI command

Usage

msgvault sync-imessage

Tested against macOS Messages database with ~10k conversations.

[roborev-ci]

roborev: Combined Review (0508613)

Summary Verdict: Adds a new sync-imessage client but contains high-severity data loss issues regarding missing attachments and attributedBody parsing, alongside bugs
with date filtering and nil pointer dereferences.

High

• internal/imessage/client.go:266 and 295

  • Problem: The importer only reads message.text. Many Messages DB rows keep the visible text only in
    attributedBody when text is NULL, so those messages will be archived as blank messages with empty snippets.
  • Fix: Select attributedBody and decode it as a fallback whenever message.text is null; add coverage for rows where only attributedBody is populated.

• internal/imessage/client.go:258 and 301

  • Problem: cache_has_attachments is fetched but never used, and the code never reads the attachment tables or emits MIME parts for them. Messages with photos/
    files/stickers will therefore be imported without their attachments, silently losing data.
  • Fix: Read attachment metadata via the join tables and feed attachment content through the existing archive pipeline, or fail/warn explicitly until attachment support is implemented.

Medium

• cmd/msgvault/ cmd/sync_imessage.go:80 and 88

  • Problem: --after and --before are parsed with time.Parse, which treats YYYY-MM-DD as midnight UTC. On a local macOS CLI this shifts the intended day boundary
    for non-UTC users, causing messages around midnight local time to be included or excluded incorrectly.
  • Fix: Parse date-only filters with time.ParseInLocation(..., time.Local) so filtering matches the user’s local calendar day.

• internal/imessage/client .go:340

  • Problem: GetMessagesRawBatch pre-allocates the results slice and continues on errors, leaving nil entries in the slice. This may cause nil pointer dereferences when the caller iterates over the results.

• Fix: Initialize var results []*gmail.RawMessage and append(results, msg) for successfully fetched messages.

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Synthesized from 3 reviews (agents: codex, gemini | types: default, security)