Waterline

Geometry-keyed flight briefings with a pilot-authorized real-time follower room.

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Inspiration

Remote lakes often have no destination identifier or weather station, but aviation briefing tools are identifier-keyed. Waterline starts from the route geometry instead: it narrows live FIR-wide hazards to the corridor, infers a bounded destination read from nearby observations, and keeps the pilot - not the model - in authority.

What it does

Waterline runs an eight-agent ADK briefing fleet over live NAV CANADA inputs. PostGIS performs exact corridor intersection, Cloud SQL/pgvector recalls owner-scoped acknowledgements, Gemini extracts a typed synthetic condition card, and deterministic checks reject east-cove plan v1 before proposing west-cove v2 for pilot review.

The run stops at ATTESTATION REQUIRED. One authenticated pilot action atomically commits a Cloud SQL handoff receipt and displays a signed one-hour QR invitation. The responsible person scans it, acknowledges flight following, and exchanges bounded realtime text with the pilot through Firestore. The cockpit changes to FOLLOWING ACTIVE · LIVE VIA FIRESTORE. Replaying the command returns the same receipt, QR, token, and expiry.

Firestore is deliberately not authoritative: its messages cannot change route, attestation, or mission state.

How we built it

  • Google ADK and Vertex AI Gemini for the private briefing fleet
  • gemini-embedding-001 for owner-scoped destination recall and advisory google/gemma-4-26b-a4b-it-maas for cardinality-preserving NOTAM ranking
  • Cloud Run public Next.js edge and private FastAPI agent
  • Cloud SQL PostgreSQL/PostGIS/pgvector for spatial queries, durable missions, owner memory, and duplicate suppression
  • Firebase Anonymous Auth plus a Cloud Run authorization bridge
  • Cloud Firestore realtime listeners with strict Security Rules and one-hour TTL
  • Secret Manager, keyless service accounts, Cloud Build, and Artifact Registry

Challenges

The hard part was separating four kinds of power: models may read and propose; deterministic code validates and writes; the authenticated pilot authorizes; Firestore coordinates without acquiring route authority. The signed invitation also had to be reproducible after refresh without storing the raw capability, so Waterline persists only expiry and SHA-256 and reconstructs the exact token from durable mission state.

Accomplishments

  • Exact geometry-keyed NOTAM reduction instead of identifier lookup
  • Typed visual extraction with digest-bound validation and hash-only hostile-text quarantine
  • Owner-scoped source-digest memory with changed hazards resurfacing
  • One durable handoff receipt under replay/concurrency
  • One-hour, two-member Firestore room with fixed acknowledgement and bounded direct chat
  • Emulator tests for unauthenticated, cross-room, expired, spoofed, oversized, extra-field, update, and delete denial

What we learned

The safest architecture was also the clearest demo: Cloud SQL remains the source of truth, Firestore is labelled ephemeral coordination, and a prominent boundary states that messages cannot mutate aviation authority. Realtime UX does not require realtime authority.

What's next

Expand only with cited, versioned water-aerodrome data and operator-reviewed escalation workflows without broadening model authority.

Upstream contribution

Building Waterline surfaced an import-time Google ADK defect: importing the supported programmatic LlmAgent API emits a deprecation warning from ADK's own internal BaseAgentConfig subclass. We reported a clean reproduction across ADK 2.7.1, 2.8.0, and current upstream main, with a narrow regression-test proposal. Issue: google/adk-python#6968.

Built With

  • cloud-firestore
  • cloud-run
  • cloud-sql
  • fastapi
  • firebase-anonymous-auth
  • gemini-3.5-flash
  • gemini-3.6-flash
  • gemini-3.7-flash
  • gemma-4-26b-maas
  • google-adk
  • maplibre
  • next.js
  • pgvector
  • postgis
  • postgresql
  • secret-manager
  • vertex-ai
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