Expand coverage for transport, chat, and media flows (#1056)

* Expand coverage for transport, chat, and media flows

* Stabilize transport and media coverage tests

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchatTests/PublicTimelineStoreTests.swift

@@ -0,0 +1,72 @@
+import Foundation
+import Testing
+@testable import bitchat
+
+@Suite("PublicTimelineStore Tests")
+struct PublicTimelineStoreTests {
+
+    @Test("Mesh timeline deduplicates and trims to cap")
+    func meshTimelineDeduplicatesAndTrims() {
+        var store = PublicTimelineStore(meshCap: 2, geohashCap: 2)
+        let first = TestHelpers.createTestMessage(content: "one")
+        let second = TestHelpers.createTestMessage(content: "two")
+        let third = TestHelpers.createTestMessage(content: "three")
+
+        store.append(first, to: .mesh)
+        store.append(second, to: .mesh)
+        store.append(first, to: .mesh)
+        store.append(third, to: .mesh)
+
+        let messages = store.messages(for: .mesh)
+        #expect(messages.map(\.content) == ["two", "three"])
+    }
+
+    @Test("Geohash appendIfAbsent remove and clear work together")
+    func geohashStoreSupportsAppendRemoveAndClear() {
+        var store = PublicTimelineStore(meshCap: 2, geohashCap: 3)
+        let geohash = "u4pruydq"
+        let channel = ChannelID.location(GeohashChannel(level: .city, geohash: geohash))
+        let first = TestHelpers.createTestMessage(content: "geo one")
+        let second = TestHelpers.createTestMessage(content: "geo two")
+
+        let didAppendFirst = store.appendIfAbsent(first, toGeohash: geohash)
+        let didAppendDuplicate = store.appendIfAbsent(first, toGeohash: geohash)
+
+        #expect(didAppendFirst)
+        #expect(!didAppendDuplicate)
+        store.append(second, toGeohash: geohash)
+        let removed = store.removeMessage(withID: first.id)
+
+        #expect(removed?.id == first.id)
+        #expect(store.messages(for: channel).map(\.content) == ["geo two"])
+
+        store.clear(channel: channel)
+        #expect(store.messages(for: channel).isEmpty)
+    }
+
+    @Test("Mutate geohash updates stored messages in place")
+    func mutateGeohashAppliesTransformation() {
+        var store = PublicTimelineStore(meshCap: 2, geohashCap: 3)
+        let geohash = "u4pruydq"
+        let channel = ChannelID.location(GeohashChannel(level: .city, geohash: geohash))
+        let first = TestHelpers.createTestMessage(content: "geo one")
+
+        store.append(first, toGeohash: geohash)
+        store.mutateGeohash(geohash) { timeline in
+            timeline.append(TestHelpers.createTestMessage(content: "geo two"))
+        }
+
+        #expect(store.messages(for: channel).map(\.content) == ["geo one", "geo two"])
+    }
+
+    @Test("Queued geohash system messages drain once")
+    func pendingGeohashSystemMessagesDrainOnce() {
+        var store = PublicTimelineStore(meshCap: 1, geohashCap: 1)
+
+        store.queueGeohashSystemMessage("first")
+        store.queueGeohashSystemMessage("second")
+
+        #expect(store.drainPendingGeohashSystemMessages() == ["first", "second"])
+        #expect(store.drainPendingGeohashSystemMessages().isEmpty)
+    }
+}