* feat(channels): add Gmail Pub/Sub push notifications for real-time email
Add GmailPushChannel that replaces IMAP polling with Google's Pub/Sub
push notification system for real-time email-driven automation.
- New channel at src/channels/gmail_push.rs implementing the Channel trait
- Registers Gmail watch subscription (POST /gmail/v1/users/me/watch)
with automatic renewal before the 7-day expiry
- Handles incoming Pub/Sub notifications at POST /webhook/gmail
- Fetches new messages via Gmail History API (startHistoryId-based)
- Dispatches email messages to the agent with full metadata
- Sends replies via Gmail messages.send API
- Config: gmail_push.enabled, topic, label_filter, oauth_token,
allowed_senders, webhook_url
- OAuth token encrypted at rest via existing secret store
- Webhook endpoint added to gateway router
- 30+ unit tests covering notification parsing, header extraction,
body decoding, sender allowlist, and config serialization
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(config): fix pre-existing test compilation errors in schema.rs
- Remove #[cfg(unix)] gate on `use tempfile::TempDir` import since
TempDir is used unconditionally in bootstrap file tests
- Add explicit type annotations on tokio::fs::* calls to resolve
type inference failures (create_dir_all, write, read_to_string)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(channels): fix extract_body_text_plain test
Gmail API sends base64url without padding. The decode_body function
converted URL-safe chars back to standard base64 but did not restore
the padding, causing STANDARD decoder to fail and falling back to
snippet. Add padding restoration before decoding.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(channels): address critical security bugs in Gmail Pub/Sub push
- Add webhook authentication via shared secret (webhook_secret config
field or GMAIL_PUSH_WEBHOOK_SECRET env var), preventing unauthorized
message injection through the unauthenticated webhook endpoint
- Add 1MB body size limit on webhook endpoint to prevent memory exhaustion
- Fix race condition in handle_notification: hold history_id lock across
the read-fetch-update cycle to prevent duplicate message processing
when concurrent webhook notifications arrive
- Sanitize RFC 2822 headers (To/Subject) to prevent CRLF injection
attacks that could add arbitrary headers to outgoing emails
- Fix extract_email_from_header panic on malformed angle brackets by
using rfind('>') and validating bracket ordering
- Add 30s default HTTP client timeout for all Gmail API calls,
preventing indefinite hangs
- Clone tx sender before message processing loop to avoid holding
the mutex lock across network calls
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Co-authored-by: Giulio V <vannini.gv@gmail.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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