Add NYC subway Transit view

Package.swift

@@ -45,6 +45,7 @@ let package = Package(
         .package(url: "https://github.com/pointfreeco/swift-snapshot-testing", from: "1.18.0"),
         .package(url: "https://github.com/cashapp/AccessibilitySnapshot", from: "0.12.0"),
         .package(url: "https://github.com/SFSafeSymbols/SFSafeSymbols", from: "7.0.0"),
+        .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.38.1"),
     ],
     targets: [
         .target(
@@ -224,6 +225,8 @@ let package = Package(
             name: "ThrowCore",
             dependencies: [
                 .target(name: "PeriscopeCore"),
+                .product(name: "SwiftProtobuf", package: "swift-protobuf"),
+                .product(name: "ZIPFoundation", package: "ZIPFoundation"),
             ],
             path: "Throw/ThrowCore/Sources",
             resources: [

Project.swift

@@ -640,6 +640,7 @@ let project = Project(
             bundleIdSuffix: "throwcore",
             productDependency: "ThrowCore",
             sources: ["Throw/ThrowCore/Tests/**"],
+            extraPackageProducts: ["SwiftProtobuf"],
         ),
         unitTests(
             name: "ThrowUITests",

Throw/AGENTS.md

@@ -25,6 +25,10 @@ WhereCore, RegionKit, or LifecycleKit into this feature.
   `RunnableProjectionExperienceID` to playlist and runtime commands.
 - Keep aircraft provider implementations in ThrowCore. ThrowUI uses the
   provider-neutral operation service and domain results.
+- Keep transit provider adapters in ThrowCore. Keep each city behind the typed
+  schedule and observation protocols. Never add agency checks to the renderer.
+- Keep exactly one Transit runtime. It can poll only while Transit is active or
+  prewarming. Treat each realtime partition as an independent failure domain.
 - Keep one experience coordinator for all scenes. Only the active and
   prewarming experience runtimes may run at the same time.
 - Exchange complete experience frames only while the projection is black.

Throw/README.md

@@ -46,10 +46,9 @@ Preview runs the same projection renderer on the device.
 
 ## Projection Views
 
-“View” is the user-facing name for a `ProjectionExperience`. Air & Space is the
-first enabled View. It contains Geography, Flights, and the planned Stars and
-Satellites layers. Transit is planned for nearby moving buses, trains, and
-ferries. This change does not include a live transit provider.
+“View” is the user-facing name for a `ProjectionExperience`. Air & Space contains
+Geography, Flights, and the planned Stars and Satellites layers. Transit first
+supports New York City subway trains.
 
 One playlist controls every projector, full-screen output, and Preview. Each
 View has a dwell duration. Automatic rotation starts only when two Views are
@@ -58,11 +57,31 @@ View visible until the new View has fresh data and a complete prepared frame.
 Both values must belong to the same activation. The surface fades to black,
 exchanges atomically, and fades back in. Two Views never share one frame.
 
-Air & Space is the only configurable View in this release. Automatic rotation
-therefore remains dormant. Transit stays in the display and preference formats
-as a planned View. It has no runnable identity, so release code cannot add it to
-the playlist or send it to the coordinator. A future runtime must add a new
-runnable identity and update the exhaustive activation switch.
+You can configure Air & Space and NYC Subway together. Then Throw can rotate
+between the two Views. Each View keeps its own Map center, viewport, labels,
+mark size, and context intensity.
+
+## NYC Subway
+
+The NYC Subway View uses the official supplemented GTFS schedule from the MTA.
+It polls the eight official GTFS Realtime feed partitions every 30 seconds.
+The schedule defines routes, stops, trip patterns, and route shapes. The
+realtime feeds provide assigned train runs and predicted stop times.
+
+The MTA feeds do not provide a continuous position for each train. Throw
+estimates each train position along its scheduled shape. A train becomes more
+certain after consecutive feed updates show its movement through stops.
+
+Throw downloads the schedule during setup and stores it in the local cache.
+It refreshes the schedule each hour while the View runs. A valid empty realtime
+response completes activation. If one partition fails, the other partitions
+continue to update. The failed partition keeps its last train positions for
+90 seconds. Then it fades them for 30 seconds.
+
+Transit data uses a provider-neutral schedule and observation boundary. An
+additional city can supply its own GTFS adapters without changing the Transit
+projection layers. The first release does not include San Francisco data,
+buses, ferries, service alerts, or accessibility status.
 
 ## Aircraft sources
 

Throw/TODOs.md

@@ -51,14 +51,9 @@ owned by the root [`TODOs.md`](../TODOs.md).
 
 ## P1s (Should do)
 
-- feat(Throw) [needs-design]: Implement the planned Transit View — the catalog
-  reserves Network and Vehicles layers
-  (`ThrowCore/Sources/ProjectionExperience.swift:67-74`), and Views presents
-  Transit as unavailable
-  (`ThrowUI/Sources/Settings/ProjectionViewsSettingsView.swift:38-42,95-102`).
-  Select a live provider, define GTFS or equivalent route geometry, and add
-  setup and credentials if required. Give its Map runtime independent polling.
-  Keep vehicles brighter than dim network and Geography context. (human
-  2026-08-26)
-
 # Completed issues
+
+- feat(Throw): Implement the first Transit View with the official NYC Subway
+  static and realtime MTA feeds. Keep the source seams independent of the city,
+  and keep route lines and train marks in the generic projection pipeline.
+  (completed 2026-08-27)