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Mission planning is an extension point the GCS exposes to plugins. This page covers how to add pattern generators, read and write missions, and write to the geofence + rally surfaces. Higher-level flight behaviors (Follow-Me, Orbit, thermal overlay, gimbal control, etc.) are scoped per-drone and ship through the extensions registry. See Multi-component plugins for the per-drone tab pattern those use.

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Capabilities

CapabilityLets the plugin…
mission.readRead the active mission and its items.
mission.writeAppend, replace, or modify mission items.
mission.pattern.registerRegister a custom pattern generator.
mission.write is high risk; the operator sees an orange badge. mission.pattern.register is medium risk because it affects what gets uploaded to the FC.

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Pattern generators

Mission Control ships built-in patterns (grid survey, spiral search, waypoint chain). A plugin adds new ones. 
import { definePlugin, type PatternGenerator } from "@altnautica/plugin-sdk";

const concentricRings: PatternGenerator = {
  id: "com.example.concentric-rings",
  name: "Concentric rings",
  description: "Inspection orbit at increasing radii.",
  fields: [
    { id: "center", kind: "latlng", label: "Center" },
    { id: "minRadius", kind: "number", label: "Min radius (m)", default: 5 },
    { id: "maxRadius", kind: "number", label: "Max radius (m)", default: 30 },
    { id: "step", kind: "number", label: "Step (m)", default: 5 },
    { id: "altitude", kind: "number", label: "Altitude (m AGL)", default: 20 },
  ],
  generate(input) {
    const items = [];
    for (let r = input.minRadius; r <= input.maxRadius; r += input.step) {
      for (let theta = 0; theta < 360; theta += 30) {
        items.push({
          kind: "waypoint",
          lat: offsetLat(input.center.lat, r, theta),
          lng: offsetLng(input.center.lng, r, theta),
          alt_agl_m: input.altitude,
        });
      }
    }
    return items;
  },
};

definePlugin({
  id: "com.example.inspection",
  version: "0.1.0",
  mount(ctx) {
    ctx.mission.registerPattern(concentricRings);
    return null;
  },
});
The host renders the form from fields[], calls generate(input) on submit, and offers the result as a preview the operator can edit before upload. fields[] field kinds:
KindRenders as
textText input
numberNumber input
booleanToggle
selectDropdown with options[]
latlngMap-pinned point picker
polygonMap polygon drawing tool
polylineMap polyline drawing tool
altitudeAltitude picker (AGL / MSL toggle)
The host validates the form and rejects out-of-range numbers before calling generate.

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Reading and writing missions

// read
const mission = await ctx.mission.read("active");
console.log(mission.items.length);

// modify
const next = {
  ...mission,
  items: [
    ...mission.items,
    { kind: "waypoint", lat: 12.97, lng: 77.59, alt_agl_m: 30 },
  ],
};
await ctx.mission.write("active", next);
The host validates the mission against the FC’s accepted item types and rejects writes with schema_invalid if anything is malformed. The validation rules are firmware-specific (ArduPilot accepts different MAV_CMDs than Betaflight) and the host applies the right rule set automatically.

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Geofence and rally points

Plugins extend missions; they do not extend geofence directly. Use the canonical mission.write with the geofence-specific mission items: 
await ctx.mission.write("geofence", {
  items: [
    { kind: "fence_polygon_inclusion", points: [...] },
    { kind: "fence_circle_exclusion", center: {...}, radius_m: 50 },
  ],
});
The host enforces a fixed schema for fence items and rejects unknown kinds.

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Pattern preview

Patterns show a live preview on the map. The host calls generate (or preview if your generator defines one) every time the form changes. Patterns must therefore be cheap; spending more than 100 ms per generate is a UX bug. For expensive generation, ship a preview that returns a coarse shape and a generate that does the full work: 
{
  preview(input) { return cheapPolygon(input); },
  generate(input) { return expensiveWaypointList(input); },
}

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Persisting custom mission types

If your generator needs to round-trip through the GCS’s mission library, add a kind discriminator to your items and register a serializer: 
ctx.mission.registerItemKind("com.example.soil-sampling", {
  serialize(item) { return { ...item, version: 1 }; },
  deserialize(blob) { return blob; },
});
The host stores serialized items in the mission row in Convex and restores them on load. The agent half ignores unknown kinds when uploading to the FC unless a handler is registered for them.

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Testing

The host ships a mock mission store the SDK exposes for tests: 
import { createMockMission } from "@altnautica/plugin-sdk/testing";

const mission = createMockMission();
await mission.write("active", { items: [...] });
const items = await mission.read("active");
expect(items.length).toBe(3);

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See also