Share a self-reported position when no AIS transponder is available

[bkeepers]

A boat with only a GPS can now appear on aiscast. When no !AIVDO has been heard for 5 minutes, the plugin builds class B position reports from Signal K (every 60 s while the position changes) and static data (name, callsign, size, every 6 min), the same thing @signalk/aisreporter does for MarineTraffic, and publishes them as !AIVDO tagged s:self.

The server marks s:self events synthesized: true. That keeps them out of the AISHub feed, whose terms forbid synthesized data, and out of a station's feeder-tier accounting. Consumers can tell them apart from VHF receptions by the flag.

Settings

The Share section is three checkboxes, each explained below its label. Fallback to self-reported AIS position is checked by default when the config form is saved. Configs saved before the setting existed stay off until re-saved, so an upgrade never starts publishing on its own. Without an MMSI in Vessel settings the checkbox is disabled with a note (uiSchema is a function, so the check runs on each config-page load).

Nothing is sent without a fix or while the GPS sits at Null Island, and an unchanged position is not repeated. SOG, COG, and heading use the AIS "not available" sentinels when Signal K lacks them; heading falls back to magnetic plus variation.

[Copilot]

Pull request overview

Adds a “self-reported own-ship” fallback so a Signal K instance with GPS but no AIS transponder can still publish AIS-like own-ship reports to aiscast, with server-side handling to mark these events as synthesized (synthesized: true) and keep them out of the AISHub feed and feeder-tier accounting.

Changes:

• Signal K plugin: synthesize and publish own-ship Class B position/static reports from Signal K data when enabled, tagged s:self.
• Server: treat s:self own-ship publishes as synthesized events; add coverage to prevent feeding to AISHub.
• Docs/tests: add unit/integration tests and update user-facing documentation for the new Share setting and synthesized semantics.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
signalk-plugin/test/plugin.test.ts	Adds an integration test asserting s:self-tagged !AIVDO publishes occur when the fallback is enabled.
signalk-plugin/test/ownship.test.ts	Adds unit tests for synthesized own-ship AIS message construction and throttling rules.
signalk-plugin/src/ownship.ts	Implements own-ship AIS synthesis from Signal K position/static data.
signalk-plugin/src/index.ts	Wires new Share setting, dynamic uiSchema MMSI gating, and starts/stops own-ship synthesis.
signalk-plugin/src/downlink.ts	Reuses shared own-position helper and adjusts loop-guard ordering for self echoes.
signalk-plugin/README.md	Documents the new Share behavior and settings text.
signalk-plugin/CHANGELOG.md	Notes the new fallback setting and UI improvements.
server/pipeline.go	Marks s:self own-ship events as synthesized for downstream handling.
server/aishub_test.go	Adds a test ensuring self-reported own-ship is synthesized and excluded from AISHub feeding.
README.md	Updates top-level project docs to mention the plugin’s fallback behavior.
PLAN.md	Updates design/behavior documentation for own-ship fallback and config semantics.
docs/API.md	Extends synthesized semantics to include s:self own-ship GPS-built reports.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.