Finish coordinator migration: zero ChatViewModel back-references remain

ChatPeerListCoordinator, ChatComposerCoordinator, ChatOutgoingCoordinator,
and GeoChannelCoordinator complete the migration; every coordinator now
depends on a narrow @MainActor context protocol. GeoChannelCoordinator's
three injected closures collapse into a weak context. New intent op
recordPublicActivity(forChannelKey:) keeps lastPublicActivityAt
single-writer. 15 new mock-context tests; flaky-poll deadline in the
gift-wrap dedup test raised for parallel load.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bitchatTests/ChatComposerCoordinatorContextTests.swift

@@ -0,0 +1,157 @@
+//
+// ChatComposerCoordinatorContextTests.swift
+// bitchatTests
+//
+// Exercises `ChatComposerCoordinator` against a mock `ChatComposerContext` —
+// proving the coordinator works without a `ChatViewModel`, following the
+// `ChatDeliveryCoordinatorContextTests` exemplar.
+//
+// Scope note: mention parsing uses the shared, precompiled
+// `ChatViewModel.Patterns.mention` regex (a static, stateless singleton);
+// everything else flows through the mock context.
+//
+
+import Testing
+import Foundation
+import BitFoundation
+@testable import bitchat
+
+// MARK: - Mock Context
+
+/// Lightweight stand-in for `ChatComposerContext` proving that
+/// `ChatComposerCoordinator` is testable without a `ChatViewModel`.
+@MainActor
+private final class MockChatComposerContext: ChatComposerContext {
+    // Autocomplete UI state
+    var autocompleteSuggestions: [String] = []
+    var autocompleteRange: NSRange?
+    var showAutocomplete = false
+    var selectedAutocompleteIndex = -1
+    var queryResult: (suggestions: [String], range: NSRange?) = ([], nil)
+    private(set) var queriedPeerCandidates: [[String]] = []
+    private(set) var appliedSuggestions: [(suggestion: String, text: String, range: NSRange)] = []
+
+    func autocompleteQuery(
+        for text: String,
+        peers: [String],
+        cursorPosition: Int
+    ) -> (suggestions: [String], range: NSRange?) {
+        queriedPeerCandidates.append(peers.sorted())
+        return queryResult
+    }
+
+    func applyAutocompleteSuggestion(_ suggestion: String, to text: String, range: NSRange) -> String {
+        appliedSuggestions.append((suggestion, text, range))
+        guard let textRange = Range(range, in: text) else { return text }
+        return text.replacingCharacters(in: textRange, with: suggestion)
+    }
+
+    // Identity & channel state
+    var nickname = "me"
+    var myPeerID = PeerID(str: "0011223344556677")
+    var activeChannel: ChannelID = .mesh
+    var meshNickname = "me"
+    var meshNicknamesByPeerID: [PeerID: String] = [:]
+
+    func meshPeerNicknames() -> [PeerID: String] { meshNicknamesByPeerID }
+
+    // Geohash identity
+    var geoNicknames: [String: String] = [:]
+    static let dummyIdentity = NostrIdentity(
+        privateKey: Data(repeating: 0x11, count: 32),
+        publicKey: Data(repeating: 0x22, count: 32),
+        npub: "npub1mock",
+        createdAt: Date(timeIntervalSince1970: 0)
+    )
+
+    func deriveNostrIdentity(forGeohash geohash: String) throws -> NostrIdentity {
+        Self.dummyIdentity
+    }
+}
+
+// MARK: - Coordinator Tests Against Mock Context
+
+/// Exercises `ChatComposerCoordinator` against `MockChatComposerContext` with
+/// no `ChatViewModel`.
+struct ChatComposerCoordinatorContextTests {
+
+    @Test @MainActor
+    func updateAutocomplete_onMesh_excludesOwnNicknameAndPublishesSuggestions() {
+        let context = MockChatComposerContext()
+        let coordinator = ChatComposerCoordinator(context: context)
+        context.meshNicknamesByPeerID = [
+            PeerID(str: "1111111111111111"): "alice",
+            PeerID(str: "2222222222222222"): "bob",
+            PeerID(str: "3333333333333333"): "me",
+        ]
+
+        // Matching query: suggestions and range are published, index resets.
+        context.queryResult = (["@alice"], NSRange(location: 0, length: 3))
+        coordinator.updateAutocomplete(for: "@al", cursorPosition: 3)
+        #expect(context.queriedPeerCandidates == [["alice", "bob"]])
+        #expect(context.autocompleteSuggestions == ["@alice"])
+        #expect(context.autocompleteRange == NSRange(location: 0, length: 3))
+        #expect(context.showAutocomplete)
+        #expect(context.selectedAutocompleteIndex == 0)
+
+        // No match: all autocomplete state is cleared.
+        context.queryResult = ([], nil)
+        context.selectedAutocompleteIndex = 3
+        coordinator.updateAutocomplete(for: "plain text", cursorPosition: 5)
+        #expect(context.autocompleteSuggestions.isEmpty)
+        #expect(context.autocompleteRange == nil)
+        #expect(!context.showAutocomplete)
+        #expect(context.selectedAutocompleteIndex == 0)
+    }
+
+    @Test @MainActor
+    func updateAutocomplete_onLocationChannel_buildsGeoTokensWithoutOwnToken() {
+        let context = MockChatComposerContext()
+        let coordinator = ChatComposerCoordinator(context: context)
+        context.activeChannel = .location(GeohashChannel(level: .city, geohash: "u4pruydq"))
+        context.geoNicknames = [
+            "aaaabbbbccccdddd": "carol",
+            // Own token (nickname#last-4-of-pubkey) must be removed; the dummy
+            // identity's public key hex ends in "2222".
+            "ffffeeeeddddcccc2222": "me",
+        ]
+
+        coordinator.updateAutocomplete(for: "@ca", cursorPosition: 3)
+        #expect(context.queriedPeerCandidates == [["carol#dddd"]])
+    }
+
+    @Test @MainActor
+    func completeNickname_appliesSuggestionResetsStateAndReturnsCursor() {
+        let context = MockChatComposerContext()
+        let coordinator = ChatComposerCoordinator(context: context)
+
+        // Without an active range the text is untouched.
+        var text = "hello @al"
+        #expect(coordinator.completeNickname("@alice", in: &text) == text.count)
+        #expect(context.appliedSuggestions.isEmpty)
+
+        // With a range the suggestion is applied and state cleared.
+        context.autocompleteRange = NSRange(location: 6, length: 3)
+        context.autocompleteSuggestions = ["@alice"]
+        context.showAutocomplete = true
+        let cursor = coordinator.completeNickname("@alice", in: &text)
+        #expect(text == "hello @alice")
+        #expect(cursor == 6 + "@alice".count + 1)
+        #expect(!context.showAutocomplete)
+        #expect(context.autocompleteSuggestions.isEmpty)
+        #expect(context.autocompleteRange == nil)
+        #expect(context.selectedAutocompleteIndex == 0)
+    }
+
+    @Test @MainActor
+    func parseMentions_acceptsKnownPeersOwnNicknameAndHashSuffix() {
+        let context = MockChatComposerContext()
+        let coordinator = ChatComposerCoordinator(context: context)
+        context.meshNicknamesByPeerID = [PeerID(str: "1111111111111111"): "alice"]
+
+        let mentions = coordinator.parseMentions(
+            from: "hi @alice and @me and @me#0011 but not @stranger"
+        )
+        #expect(Set(mentions) == ["alice", "me", "me#0011"])
+    }
+}