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+# Phase 1E -- SignalR wrapper contracts
+
+## Goal
+
+Deliver a reference-counted SignalR connection wrapper and a generic SSR-safe React hook (`useLiveFlights`) that subscribes to live flight data channels. All SignalR imports are dynamic so they never enter the SSR bundle.
+
+## Deliverables
+
+| File | Purpose |
+|---|---|
+| `src/shared/signalr/connection.ts` | `SignalRConnection` class, `getSharedConnection`, `ConnectionStatus` type, `HubOptions` interface |
+| `src/shared/signalr/connection.test.ts` | Vitest tests for connection lifecycle, ref-counting, grace period, status changes |
+| `src/shared/hooks/useLiveFlights.ts` | Generic live-data hook wrapping SignalR subscription |
+| `src/shared/hooks/useLiveFlights.test.ts` | Vitest tests for hook behavior including SSR path |
+
+## Tasks
+
+### Task 1 -- Install `@microsoft/signalr`
+
+Add `@microsoft/signalr` to the root `package.json` dependencies.
+
+**Commit:** "Add @microsoft/signalr dependency"
+
+### Task 2 -- `SignalRConnection` class + tests
+
+Create `src/shared/signalr/connection.ts` with:
+
+- `HubOptions` interface: `hubUrl`, `reconnectDelaysMs` (default `[0, 2000, 10000, 30000]`), `gracePeriodMs` (default `5000`)
+- `ConnectionStatus` type: `"idle" | "connecting" | "live" | "reconnecting" | "offline"`
+- `SignalRConnection` class:
+  - Constructor takes `HubOptions`, uses dynamic `import("@microsoft/signalr")` to build connection
+  - `subscribe(channel, handler)` returns unsubscribe fn; increments ref count; starts connection on first subscriber
+  - `onStatusChange(handler)` returns unsubscribe fn
+  - `get status()` returns current `ConnectionStatus`
+  - Reference counting: connection closes after last unsubscribe + grace period elapses
+- `getSharedConnection(options)` -- singleton map keyed by `hubUrl`
+
+Create `src/shared/signalr/connection.test.ts` with tests:
+
+1. Two rapid subscribes produce exactly one `HubConnection.start()` call
+2. Unmount + remount within grace period reuses connection (no second `start()`)
+3. Unmount + remount after grace period creates fresh connection
+4. Status transitions fire `onStatusChange` handlers
+5. `getSharedConnection` returns same instance for same `hubUrl`
+
+**Commit:** "Add SignalRConnection ref-counted wrapper with tests"
+
+### Task 3 -- `useLiveFlights` hook + tests
+
+Create `src/shared/hooks/useLiveFlights.ts`:
+
+- Generic `useLiveFlights<TParams, TData>(params, initialData, config)` hook
+- SSR-safe: checks `typeof window !== "undefined"` before subscribing
+- Uses `useEffect` for subscribe/unsubscribe lifecycle
+- Returns `{ data: TData[]; connectionStatus: ConnectionStatus }`
+
+Create `src/shared/hooks/useLiveFlights.test.ts`:
+
+1. SSR path returns `initialData` without importing `@microsoft/signalr`
+2. Client path subscribes to the correct channel
+3. Data updates when messages arrive
+4. Cleanup unsubscribes on unmount
+
+**Commit:** "Add useLiveFlights SSR-safe hook with tests"
+
+### Task 4 -- Verification
+
+- `pnpm typecheck && pnpm lint && pnpm test`
+- Confirm ESLint SSR-bundle guard still blocks `@microsoft/signalr` in `src/routes/`
+
+**Commit:** none (verification only)
+
+## Exit gate
+
+- Two rapid `useEffect` mounts (Strict Mode simulation) result in exactly one `HubConnection.start()` call
+- Unmount + remount within grace period reuses connection
+- Unmount + remount after grace period creates fresh connection
+- SSR render path does not import `@microsoft/signalr`
+- `pnpm typecheck && pnpm lint && pnpm test` all green