Merge pull request #87 from awizemann/ws-5-gateway-v0.13

feat(gateway): Google Chat + allowlists + behavior toggles (WS-5)

scarf/Packages/ScarfCore/Sources/ScarfCore/Models/GatewayAllowlistKind.swift

@@ -0,0 +1,76 @@
+import Foundation
+
+/// Hermes v0.13 added cross-platform recipient allowlists to the Messaging
+/// Gateway. Each platform stores the list under a different YAML key
+/// depending on the platform's primary noun for "addressable destination":
+///
+/// - **`allowed_channels`** — Slack, Mattermost, Google Chat
+/// - **`allowed_chats`** — Telegram, WhatsApp
+/// - **`allowed_rooms`** — Matrix, DingTalk
+///
+/// `GatewayAllowlistKind` encodes the (platform → key) mapping plus a few
+/// presentation hints (placeholder strings, singular noun) so the allowlist
+/// editor can render the right copy without the per-platform setup view
+/// needing to know the YAML shape.
+public enum GatewayAllowlistKind: String, Sendable, Equatable {
+    case channels   // -> allowed_channels
+    case chats      // -> allowed_chats
+    case rooms      // -> allowed_rooms
+
+    /// YAML scalar key segment under `gateway.platforms.<platform>.<key>`.
+    public var yamlKey: String {
+        switch self {
+        case .channels: return "allowed_channels"
+        case .chats:    return "allowed_chats"
+        case .rooms:    return "allowed_rooms"
+        }
+    }
+
+    /// Placeholder copy for the editor's "add row" text field. Picks the
+    /// most common identifier shape per platform family — Slack channel IDs
+    /// for `channels`, Telegram username/numeric for `chats`, Matrix room
+    /// IDs for `rooms`. Users can paste in any platform-specific format the
+    /// gateway accepts; this is a hint, not validation.
+    public var inputPlaceholder: String {
+        switch self {
+        case .channels: return "C0123ABCD or #channel-name"
+        case .chats:    return "@username or 12345678"
+        case .rooms:    return "!RoomId:matrix.org"
+        }
+    }
+
+    /// Singular noun for prose surfaces ("Add a channel", "1 chat allowed",
+    /// "0 rooms"). Capitalization is the caller's responsibility.
+    public var noun: String {
+        switch self {
+        case .channels: return "channel"
+        case .chats:    return "chat"
+        case .rooms:    return "room"
+        }
+    }
+
+    /// Plural noun for headings + counts.
+    public var pluralNoun: String {
+        switch self {
+        case .channels: return "channels"
+        case .chats:    return "chats"
+        case .rooms:    return "rooms"
+        }
+    }
+
+    /// Map a Hermes platform identifier to the allowlist kind it supports.
+    /// Returns `nil` for platforms without v0.13 allowlist support
+    /// (`cli`, `signal`, `email`, `imessage`, `homeassistant`, `webhook`,
+    /// `yuanbao`, `microsoft-teams`, `feishu`, `discord`).
+    ///
+    /// `googlechat` and `google-chat` both map to `.channels` so we round-trip
+    /// regardless of which spelling Hermes lands on. // TODO(WS-5-Q1)
+    public static func kind(for platform: String) -> GatewayAllowlistKind? {
+        switch platform {
+        case "slack", "mattermost", "google-chat", "googlechat": return .channels
+        case "telegram", "whatsapp":                              return .chats
+        case "matrix", "dingtalk":                                return .rooms
+        default: return nil
+        }
+    }
+}

scarf/Packages/ScarfCore/Sources/ScarfCore/Models/GatewayPlatformSettings.swift

@@ -0,0 +1,71 @@
+import Foundation
+
+/// Per-platform Messaging Gateway settings introduced in Hermes v0.13. Bundles
+/// the allowlist (the platform-appropriate flavor of `allowed_channels` /
+/// `allowed_chats` / `allowed_rooms`) and three behavior toggles
+/// (`busy_ack_enabled`, `gateway_restart_notification`,
+/// `slash_command_notice_ttl_seconds`).
+///
+/// The struct carries all three list fields so a single shape fits every
+/// platform; only the field matching `GatewayAllowlistKind.kind(for:)` is
+/// surfaced in the editor for a given platform. The other two stay empty
+/// and round-trip through the YAML parser unchanged.
+///
+/// **Defaults track Hermes v0.13.** `busyAckEnabled = true`,
+/// `gatewayRestartNotification = false`, `slashCommandNoticeTTLSeconds = 0`
+/// (disabled). An "all-default" instance therefore produces no `gateway:`
+/// block in YAML — see `HermesConfig+YAML` parsing logic which only inserts
+/// an entry into `gatewayPlatforms` when at least one v0.13 key is present
+/// in the file.
+public struct GatewayPlatformSettings: Sendable, Equatable {
+    /// `gateway.platforms.<platform>.allowed_channels` — Slack, Mattermost,
+    /// Google Chat. Empty when the platform doesn't use channels.
+    public var allowedChannels: [String]
+    /// `gateway.platforms.<platform>.allowed_chats` — Telegram, WhatsApp.
+    /// Empty when the platform doesn't use chats.
+    public var allowedChats: [String]
+    /// `gateway.platforms.<platform>.allowed_rooms` — Matrix, DingTalk.
+    /// Empty when the platform doesn't use rooms.
+    public var allowedRooms: [String]
+    /// `gateway.platforms.<platform>.busy_ack_enabled`. Default `true` — set
+    /// to `false` to suppress per-message "agent is working…" acks.
+    public var busyAckEnabled: Bool
+    /// `gateway.platforms.<platform>.gateway_restart_notification`. Default
+    /// `false` — set to `true` to post a "Gateway restarted" notice on boot.
+    public var gatewayRestartNotification: Bool
+    /// `gateway.platforms.<platform>.slash_command_notice_ttl_seconds`.
+    /// Default `0` (disabled). Positive values auto-delete slash-command
+    /// notices after N seconds.
+    public var slashCommandNoticeTTLSeconds: Int
+
+    public init(
+        allowedChannels: [String] = [],
+        allowedChats: [String] = [],
+        allowedRooms: [String] = [],
+        busyAckEnabled: Bool = true,
+        gatewayRestartNotification: Bool = false,
+        slashCommandNoticeTTLSeconds: Int = 0
+    ) {
+        self.allowedChannels = allowedChannels
+        self.allowedChats = allowedChats
+        self.allowedRooms = allowedRooms
+        self.busyAckEnabled = busyAckEnabled
+        self.gatewayRestartNotification = gatewayRestartNotification
+        self.slashCommandNoticeTTLSeconds = slashCommandNoticeTTLSeconds
+    }
+
+    /// All-default instance. `HermesConfig.empty` initializes
+    /// `gatewayPlatforms: [:]` so this is rarely used directly; provided
+    /// for symmetry with the other settings types.
+    public static let empty = GatewayPlatformSettings()
+
+    /// The list field matching this allowlist kind, or `nil` for
+    /// platforms without an allowlist surface.
+    public func items(for kind: GatewayAllowlistKind) -> [String] {
+        switch kind {
+        case .channels: return allowedChannels
+        case .chats:    return allowedChats
+        case .rooms:    return allowedRooms
+        }
+    }
+}

scarf/Packages/ScarfCore/Sources/ScarfCore/Models/HermesConfig.swift

@@ -667,6 +667,17 @@ public struct HermesConfig: Sendable {
     /// useful for cost auditing and screen-recording demos.
     public var runtimeMetadataFooter: Bool
 
+    // -- Hermes v0.13 additions ----------------------------------------
+    // Per-platform Messaging Gateway settings dictionary keyed by Hermes
+    // platform identifier (`slack`, `telegram`, `matrix`, `mattermost`,
+    // `whatsapp`, `dingtalk`, `google-chat`). Populated only for platforms
+    // whose `gateway.platforms.<platform>.*` block exists in config.yaml —
+    // platforms without an explicit block don't appear in the dictionary.
+    // Editing surfaces (per-platform setup forms) read with a `?? .empty`
+    // fallback so a missing entry behaves identically to an all-default
+    // entry.
+    public var gatewayPlatforms: [String: GatewayPlatformSettings]
+
     // Grouped blocks
     public var display: DisplaySettings
     public var terminal: TerminalSettings
@@ -747,11 +758,13 @@ public struct HermesConfig: Sendable {
         homeAssistant: HomeAssistantSettings,
         cacheTTL: String = "5m",
         redactionEnabled: Bool = false,
-        runtimeMetadataFooter: Bool = false
+        runtimeMetadataFooter: Bool = false,
+        gatewayPlatforms: [String: GatewayPlatformSettings] = [:]
     ) {
         self.cacheTTL = cacheTTL
         self.redactionEnabled = redactionEnabled
         self.runtimeMetadataFooter = runtimeMetadataFooter
+        self.gatewayPlatforms = gatewayPlatforms
         self.model = model
         self.provider = provider
         self.maxTurns = maxTurns

scarf/Packages/ScarfCore/Sources/ScarfCore/Models/HermesTool.swift

@@ -60,6 +60,17 @@ public enum KnownPlatforms {
         // platform identifiers.
         HermesToolPlatform(name: "yuanbao", displayName: "Yuanbao 元宝", icon: "bubble.left.and.bubble.right.fill"),
         HermesToolPlatform(name: "microsoft-teams", displayName: "Microsoft Teams", icon: "person.2.fill"),
+        // -- v0.13 additions ---------------------------------------------
+        // Google Chat is the 20th gateway platform. It's a generic
+        // `env_enablement_fn` / `cron_deliver_env_var`-driven adapter; setup
+        // runs through `hermes setup` rather than per-field forms because
+        // the auth dance is OAuth-style and lives outside Scarf. Identifier
+        // is `google-chat` (kebab-case, mirroring `microsoft-teams`).
+        // TODO(WS-5-Q1): verify identifier against Hermes v0.13 GA — if it
+        // ships as `googlechat` instead, update both this entry and
+        // `KnownPlatforms.icon(for:)` below. `GatewayAllowlistKind.kind(for:)`
+        // already accepts both spellings defensively.
+        HermesToolPlatform(name: "google-chat", displayName: "Google Chat", icon: "bubble.left.fill"),
     ]
 
     public static func icon(for platform: String) -> String {
@@ -79,6 +90,7 @@ public enum KnownPlatforms {
         case "imessage": return "message.fill"
         case "yuanbao": return "bubble.left.and.bubble.right.fill"
         case "microsoft-teams": return "person.2.fill"
+        case "google-chat", "googlechat": return "bubble.left.fill"
         default: return "bubble.left"
         }
     }

scarf/Packages/ScarfCore/Sources/ScarfCore/Parsing/HermesConfig+YAML.swift

@@ -225,6 +225,58 @@ public extension HermesConfig {
             cooldownSeconds: int("platforms.homeassistant.extra.cooldown_seconds", default: 30)
         )
 
+        // -- v0.13: per-platform Messaging Gateway settings --------------
+        // Read `gateway.platforms.<platform>.{allowed_channels|allowed_chats|
+        // allowed_rooms|busy_ack_enabled|gateway_restart_notification|
+        // slash_command_notice_ttl_seconds}` and bundle each platform that
+        // has at least one v0.13 key present in the file. Platforms without
+        // an explicit block don't appear in the dictionary, so the
+        // editor's `?? .empty` fallback hands the user the v0.13 defaults
+        // without leaving stale keys littered across the YAML.
+        //
+        // TODO(WS-5-Q2): the `gateway.platforms.*` path is unverified —
+        // Hermes v0.13 may emit allowlists under `platforms.<platform>.*`
+        // (sibling to existing `platforms.slack.reply_to_mode`) instead.
+        // If so, swap the `prefix` line below to `"platforms.\(platform)."`
+        // and update `GatewayConfigWriter` in lockstep.
+        let gatewayAllowlistPlatforms = [
+            "slack", "mattermost", "google-chat",
+            "telegram", "whatsapp",
+            "matrix", "dingtalk",
+        ]
+        var gatewayPlatforms: [String: GatewayPlatformSettings] = [:]
+        for platform in gatewayAllowlistPlatforms {
+            let prefix = "gateway.platforms.\(platform)."
+            let allowedChannels = lists[prefix + "allowed_channels"] ?? []
+            let allowedChats    = lists[prefix + "allowed_chats"]    ?? []
+            let allowedRooms    = lists[prefix + "allowed_rooms"]    ?? []
+            let busy            = bool(prefix + "busy_ack_enabled", default: true)
+            let restartNotice   = bool(prefix + "gateway_restart_notification",
+                                       default: false)
+            let ttl             = int(prefix + "slash_command_notice_ttl_seconds",
+                                      default: 0)
+            // Skip platforms with no v0.13 fields present anywhere in the
+            // file. Without this guard, every supported platform would
+            // round-trip an all-default block back through writes even
+            // when the user never touched the new surface.
+            let isEmpty = allowedChannels.isEmpty
+                && allowedChats.isEmpty
+                && allowedRooms.isEmpty
+                && values[prefix + "busy_ack_enabled"] == nil
+                && values[prefix + "gateway_restart_notification"] == nil
+                && values[prefix + "slash_command_notice_ttl_seconds"] == nil
+            if !isEmpty {
+                gatewayPlatforms[platform] = GatewayPlatformSettings(
+                    allowedChannels: allowedChannels,
+                    allowedChats: allowedChats,
+                    allowedRooms: allowedRooms,
+                    busyAckEnabled: busy,
+                    gatewayRestartNotification: restartNotice,
+                    slashCommandNoticeTTLSeconds: ttl
+                )
+            }
+        }
+
         self.init(
             model: str("model.default", default: "unknown"),
             provider: str("model.provider", default: "unknown"),
@@ -284,7 +336,8 @@ public extension HermesConfig {
             homeAssistant: homeAssistant,
             cacheTTL: str("prompt_caching.cache_ttl", default: "5m"),
             redactionEnabled: bool("redaction.enabled", default: false),
-            runtimeMetadataFooter: bool("agent.runtime_metadata_footer", default: false)
+            runtimeMetadataFooter: bool("agent.runtime_metadata_footer", default: false),
+            gatewayPlatforms: gatewayPlatforms
         )
     }
 }

scarf/Packages/ScarfCore/Sources/ScarfCore/Services/GatewayConfigWriter.swift

@@ -0,0 +1,396 @@
+import Foundation
+
+/// Direct YAML editor for `gateway.platforms.<platform>.allowed_<kind>:` list
+/// blocks. Hermes v0.13 added these list-valued keys, but `hermes config set`
+/// stringifies arrays (the same gotcha that forced Home Assistant's watch
+/// lists to stay read-only). The Messaging Gateway editor sidesteps the CLI
+/// for these keys by editing `~/.hermes/config.yaml` directly.
+///
+/// **Pure-function `setList`** is the heart of the editor — it splits the
+/// YAML into lines, finds (or creates) the targeted block, and splices the
+/// new items in while preserving every byte outside the block. The async
+/// `saveList` wrapper wires it through `ServerContext.readText` /
+/// `writeText`, so the same code path works on `.local` and `.ssh` servers
+/// — local goes through `LocalTransport`, remote round-trips via SCP.
+///
+/// **Scalar fields don't go through here.** `busy_ack_enabled`,
+/// `gateway_restart_notification`, and `slash_command_notice_ttl_seconds`
+/// are scalars that `hermes config set` handles cleanly — `GatewayBehaviorViewModel`
+/// routes those through `PlatformSetupHelpers.saveForm` like every other
+/// platform toggle.
+///
+/// **Why not use a real YAML library?** Same answer as everywhere else in
+/// Scarf: zero external dependencies. The Hermes config flavor is a tightly
+/// scoped subset (indent-based blocks, scalar-or-list values, no anchors /
+/// aliases / flow style), and the targeted edit doesn't need to understand
+/// the full grammar — only "find this block, replace it, preserve the rest".
+public enum GatewayConfigWriter {
+
+    /// Insert or replace `gateway.platforms.<platform>.<key>:` block in the
+    /// YAML, preserving everything else byte-for-byte.
+    ///
+    /// - When `items` is empty, the block (and only the block — siblings
+    ///   stay) is removed from the YAML if present, and the function is a
+    ///   no-op if the block was already absent.
+    /// - When the block is absent and `items` is non-empty, the function
+    ///   appends a `gateway:` / `platforms:` / `<platform>:` scaffold at
+    ///   the end of the file, creating any missing ancestors. This keeps
+    ///   the function idempotent on round-trip but means the new block is
+    ///   appended rather than spliced into an existing top-level
+    ///   `gateway:` section. (See WS-5 plan §Notes for the trade-off; the
+    ///   alternative would mean reflowing existing siblings, which is the
+    ///   exact opposite of "preserve the surrounding YAML byte-for-byte".)
+    /// - When the block is present, its bullet rows are replaced with the
+    ///   new items at the same indent. Items containing YAML-special
+    ///   characters (`:` `#` `@` or leading whitespace) are single-quoted
+    ///   defensively.
+    public static func setList(
+        in yaml: String,
+        platform: String,
+        key: String,
+        items: [String]
+    ) -> String {
+        let blockIndent = 6  // `gateway:\n  platforms:\n    <platform>:\n      <key>:`
+        let itemIndent = 8
+
+        let lines = yaml.components(separatedBy: "\n")
+        let blockHeaderText = "      \(key):"   // indented match for find()
+        let trimmedItems = items.filter { !$0.trimmingCharacters(in: .whitespaces).isEmpty }
+
+        // Locate `      <key>:` whose lineage is gateway → platforms → <platform>.
+        // We find the start of the gateway block, walk down the indent tree, and
+        // bail out if any ancestor is missing.
+        let location = locateBlock(
+            in: lines,
+            platform: platform,
+            key: key
+        )
+
+        switch location {
+        case .found(let blockRange):
+            return replaceBlock(
+                in: lines,
+                blockRange: blockRange,
+                key: key,
+                items: trimmedItems,
+                blockIndent: blockIndent,
+                itemIndent: itemIndent
+            )
+        case .platformPresentKeyMissing(let insertAfter):
+            if trimmedItems.isEmpty {
+                // No-op: empty target, no existing block.
+                return yaml
+            }
+            return spliceNewKey(
+                lines: lines,
+                insertAfterLineIndex: insertAfter,
+                key: key,
+                items: trimmedItems,
+                itemIndent: itemIndent
+            )
+        case .ancestorMissing:
+            if trimmedItems.isEmpty {
+                // Nothing to write, no existing block.
+                return yaml
+            }
+            return appendScaffold(
+                yaml: yaml,
+                platform: platform,
+                key: key,
+                items: trimmedItems
+            )
+        }
+
+        // (unreachable — switch is exhaustive)
+        _ = blockHeaderText
+    }
+
+    /// Async wrapper that reads, mutates, writes via the given context.
+    /// Returns `false` on read or write failure.
+    ///
+    /// The actual I/O happens via `ServerContext.readText` / `writeText`,
+    /// which are `nonisolated` — safe to call from `MainActor` for the
+    /// short config.yaml writes the platform setup forms run. For remote
+    /// hosts the call rounds through SCP under `Task.detached` upstream
+    /// (per Swift 6 concurrency rules in `~/.claude/CLAUDE.md`).
+    public static func saveList(
+        context: ServerContext,
+        platform: String,
+        key: String,
+        items: [String]
+    ) -> Bool {
+        let path = context.paths.configYAML
+        let existing = context.readText(path) ?? ""
+        let updated = setList(in: existing, platform: platform, key: key, items: items)
+        if updated == existing { return true }   // no-op: already correct
+        return context.writeText(path, content: updated)
+    }
+
+    // MARK: - Internals
+
+    /// Result of locating the targeted block in the YAML line array.
+    private enum BlockLocation {
+        /// Block found; the closed range covers the header line + all bullet
+        /// rows attributed to it. Replacing this slice with the new block
+        /// completes the edit.
+        case found(ClosedRange<Int>)
+        /// `gateway → platforms → <platform>` exists, but the leaf `<key>:`
+        /// is absent under it. The associated value is the line index after
+        /// which the new key should be inserted (last line in the platform's
+        /// block, or the platform header itself if the platform's body is
+        /// empty).
+        case platformPresentKeyMissing(insertAfter: Int)
+        /// One of the ancestor section headers is missing. The whole
+        /// scaffold needs to be appended.
+        case ancestorMissing
+    }
+
+    private static func locateBlock(
+        in lines: [String],
+        platform: String,
+        key: String
+    ) -> BlockLocation {
+        // Walk top-to-bottom looking for `gateway:` at indent 0.
+        guard let gatewayIdx = firstIndex(of: lines, headerLineEqualTo: "gateway:", indent: 0) else {
+            return .ancestorMissing
+        }
+        // Inside `gateway:`, find `  platforms:` at indent 2.
+        guard let platformsIdx = firstIndex(
+            of: lines,
+            after: gatewayIdx,
+            headerLineEqualTo: "platforms:",
+            indent: 2,
+            stopWhenIndentLessThan: 2
+        ) else {
+            return .ancestorMissing
+        }
+        // Inside `platforms:`, find `    <platform>:` at indent 4.
+        guard let platformIdx = firstIndex(
+            of: lines,
+            after: platformsIdx,
+            headerLineEqualTo: "\(platform):",
+            indent: 4,
+            stopWhenIndentLessThan: 4
+        ) else {
+            return .ancestorMissing
+        }
+
+        // Inside the platform block, find `<key>:` at indent 6, OR the end
+        // of the platform's body if the key is missing.
+        var keyIdx: Int?
+        var lastBodyIdx = platformIdx
+        var i = platformIdx + 1
+        while i < lines.count {
+            let line = lines[i]
+            let indent = leadingSpaces(line)
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+            if trimmed.isEmpty || trimmed.hasPrefix("#") {
+                i += 1
+                continue
+            }
+            if indent < 6 {
+                // Out of the platform's block.
+                break
+            }
+            if indent == 6 && trimmed == "\(key):" {
+                keyIdx = i
+                break
+            }
+            lastBodyIdx = i
+            i += 1
+        }
+
+        guard let keyIdx else {
+            return .platformPresentKeyMissing(insertAfter: lastBodyIdx)
+        }
+
+        // Walk down the bullet rows until we leave the block (indent shrinks
+        // below the bullet indent OR we hit a sibling key at indent 6).
+        var endIdx = keyIdx
+        var j = keyIdx + 1
+        while j < lines.count {
+            let line = lines[j]
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+            if trimmed.isEmpty || trimmed.hasPrefix("#") {
+                j += 1
+                continue
+            }
+            let indent = leadingSpaces(line)
+            // Block-style YAML allows bullets at the same indent as their
+            // parent key; tolerate 6-space `- item` rows alongside the
+            // canonical 8-space ones.
+            let isBullet = trimmed.hasPrefix("- ")
+            if isBullet && (indent == 8 || indent == 6) {
+                endIdx = j
+                j += 1
+                continue
+            }
+            // Anything not a bullet at indent ≥ 8 ends the block.
+            if indent <= 6 {
+                break
+            }
+            // Indent > 8 with no bullet — unusual but tolerate (e.g. inline
+            // continuation). Treat as still in the block and advance.
+            endIdx = j
+            j += 1
+        }
+
+        return .found(keyIdx...endIdx)
+    }
+
+    private static func replaceBlock(
+        in lines: [String],
+        blockRange: ClosedRange<Int>,
+        key: String,
+        items: [String],
+        blockIndent: Int,
+        itemIndent: Int
+    ) -> String {
+        var newLines = Array(lines.prefix(blockRange.lowerBound))
+        if !items.isEmpty {
+            newLines.append("\(spaces(blockIndent))\(key):")
+            for item in items {
+                newLines.append("\(spaces(itemIndent))- \(yamlQuoteIfNeeded(item))")
+            }
+        }
+        // Drop the old block but keep everything after it.
+        let tailStart = blockRange.upperBound + 1
+        if tailStart < lines.count {
+            newLines.append(contentsOf: lines.suffix(from: tailStart))
+        }
+        return newLines.joined(separator: "\n")
+    }
+
+    private static func spliceNewKey(
+        lines: [String],
+        insertAfterLineIndex: Int,
+        key: String,
+        items: [String],
+        itemIndent: Int
+    ) -> String {
+        var newLines = Array(lines.prefix(insertAfterLineIndex + 1))
+        newLines.append("      \(key):")
+        for item in items {
+            newLines.append("\(spaces(itemIndent))- \(yamlQuoteIfNeeded(item))")
+        }
+        if insertAfterLineIndex + 1 < lines.count {
+            newLines.append(contentsOf: lines.suffix(from: insertAfterLineIndex + 1))
+        }
+        return newLines.joined(separator: "\n")
+    }
+
+    private static func appendScaffold(
+        yaml: String,
+        platform: String,
+        key: String,
+        items: [String]
+    ) -> String {
+        var trimmed = yaml
+        // Ensure exactly one trailing newline before the appended block,
+        // so the scaffold sits on its own line cleanly.
+        while trimmed.hasSuffix("\n\n") {
+            trimmed.removeLast()
+        }
+        if !trimmed.isEmpty && !trimmed.hasSuffix("\n") {
+            trimmed.append("\n")
+        }
+        var lines: [String] = []
+        if !trimmed.isEmpty {
+            lines.append("")  // blank separator
+        }
+        lines.append("gateway:")
+        lines.append("  platforms:")
+        lines.append("    \(platform):")
+        lines.append("      \(key):")
+        for item in items {
+            lines.append("        - \(yamlQuoteIfNeeded(item))")
+        }
+        lines.append("")  // trailing newline so subsequent edits append cleanly
+        return trimmed + lines.joined(separator: "\n")
+    }
+
+    // MARK: - YAML scanning helpers
+
+    private static func leadingSpaces(_ line: String) -> Int {
+        var n = 0
+        for c in line {
+            if c == " " { n += 1 } else { break }
+        }
+        return n
+    }
+
+    /// Find the first line whose trimmed content equals `header` AND whose
+    /// leading-space count equals `indent`. Comment-only and blank lines
+    /// are skipped. Returns the line's index or `nil`.
+    private static func firstIndex(
+        of lines: [String],
+        headerLineEqualTo header: String,
+        indent: Int
+    ) -> Int? {
+        for (i, line) in lines.enumerated() {
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+            if trimmed.isEmpty || trimmed.hasPrefix("#") { continue }
+            if leadingSpaces(line) == indent && trimmed == header {
+                return i
+            }
+        }
+        return nil
+    }
+
+    /// Scoped variant: search starts at `after + 1`, stops if a line at indent
+    /// `< stopWhenIndentLessThan` is encountered (we've left the parent block).
+    private static func firstIndex(
+        of lines: [String],
+        after: Int,
+        headerLineEqualTo header: String,
+        indent: Int,
+        stopWhenIndentLessThan: Int
+    ) -> Int? {
+        var i = after + 1
+        while i < lines.count {
+            let line = lines[i]
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+            if trimmed.isEmpty || trimmed.hasPrefix("#") {
+                i += 1
+                continue
+            }
+            let lineIndent = leadingSpaces(line)
+            if lineIndent < stopWhenIndentLessThan {
+                return nil
+            }
+            if lineIndent == indent && trimmed == header {
+                return i
+            }
+            i += 1
+        }
+        return nil
+    }
+
+    private static func spaces(_ n: Int) -> String {
+        String(repeating: " ", count: n)
+    }
+
+    /// Quote a YAML scalar if it contains characters that the parser would
+    /// otherwise interpret as structure (colon, hash, leading at-sign, etc.).
+    /// Plain alphanumeric IDs (the common case for Slack channel IDs and
+    /// Telegram numeric chat IDs) are emitted unquoted.
+    private static func yamlQuoteIfNeeded(_ raw: String) -> String {
+        if raw.isEmpty { return "''" }
+        let needsQuoting = raw.contains(":")
+            || raw.contains("#")
+            || raw.contains("&")
+            || raw.contains("*")
+            || raw.contains(">")
+            || raw.contains("|")
+            || raw.first == "@"
+            || raw.first == "-"
+            || raw.first == " "
+            || raw.last == " "
+            || raw.first == "\""
+            || raw.first == "'"
+        if !needsQuoting { return raw }
+        // Single-quote, escaping any embedded single quotes by doubling.
+        let escaped = raw.replacingOccurrences(of: "'", with: "''")
+        return "'\(escaped)'"
+    }
+}

scarf/Packages/ScarfCore/Sources/ScarfCore/Services/HermesGatewayListService.swift

@@ -0,0 +1,151 @@
+import Foundation
+
+/// Cross-profile snapshot returned by `hermes gateway list --json` (Hermes
+/// v0.13+). Each profile is one configured Messaging Gateway instance — most
+/// users have a single `default` profile, but power users keep separate
+/// profiles for work / personal / project-specific accounts.
+public struct GatewayListSnapshot: Sendable, Equatable {
+    public struct ProfileEntry: Sendable, Equatable {
+        public let profile: String
+        public let isRunning: Bool
+        public let pid: Int?
+        public let platforms: [String]   // platform names connected/configured
+
+        public init(
+            profile: String,
+            isRunning: Bool,
+            pid: Int?,
+            platforms: [String]
+        ) {
+            self.profile = profile
+            self.isRunning = isRunning
+            self.pid = pid
+            self.platforms = platforms
+        }
+    }
+    public let profiles: [ProfileEntry]
+    public let detectedAt: Date
+
+    public init(profiles: [ProfileEntry], detectedAt: Date = Date()) {
+        self.profiles = profiles
+        self.detectedAt = detectedAt
+    }
+
+    /// One-line digest for the Messaging Gateway page header. Format depends
+    /// on shape:
+    /// - 0 profiles: `"no profiles configured"`
+    /// - 1 profile, running: `"default profile · running · slack, telegram"`
+    /// - 1 profile, stopped: `"default profile · stopped"`
+    /// - >1 profile: `"3 profiles (2 running) · default: slack, telegram"`
+    public var headerDigest: String {
+        if profiles.isEmpty { return "no profiles configured" }
+
+        if profiles.count == 1 {
+            let p = profiles[0]
+            let state = p.isRunning ? "running" : "stopped"
+            if p.isRunning && !p.platforms.isEmpty {
+                let plats = p.platforms.joined(separator: ", ")
+                return "\(p.profile) profile · \(state) · \(plats)"
+            }
+            return "\(p.profile) profile · \(state)"
+        }
+
+        let runningCount = profiles.filter(\.isRunning).count
+        // Surface the platforms of the first running profile (or first profile
+        // if none are running) so the digest carries one specimen of context
+        // beyond just counts.
+        let highlight = profiles.first(where: \.isRunning) ?? profiles[0]
+        let platsClause: String
+        if highlight.platforms.isEmpty {
+            platsClause = ""
+        } else {
+            platsClause = " · \(highlight.profile): \(highlight.platforms.joined(separator: ", "))"
+        }
+        return "\(profiles.count) profiles (\(runningCount) running)\(platsClause)"
+    }
+}
+
+/// Pure parser + sync fetcher for `hermes gateway list --json`. Pre-v0.13
+/// hosts exit non-zero on the unknown subcommand; the fetcher returns `nil`
+/// in that case so the digest row hides itself.
+///
+/// The detection is **synchronous** — run from a `Task.detached` to avoid
+/// blocking MainActor on remote SSH round-trips. The pure `parse(_:)`
+/// helper has no I/O and can be used in tests against canned JSON.
+public enum HermesGatewayListService {
+
+    /// Parse a JSON blob from `hermes gateway list --json` into a snapshot.
+    /// Tolerant of unknown keys; returns `nil` for unparseable / empty input.
+    ///
+    /// // TODO(WS-5-Q3): the JSON shape below is the plan's best-guess.
+    /// Confirm against actual Hermes v0.13 output once available. Possible
+    /// alternative shapes:
+    /// - root array of profile objects (no `profiles` wrapper)
+    /// - `state` enum string instead of `running` bool
+    /// - `connected_platforms` instead of `platforms`
+    /// The parser is intentionally tolerant so a small shape change can be
+    /// absorbed by tweaking field names without breaking older fixtures.
+    public static func parse(_ json: Data) -> GatewayListSnapshot? {
+        guard !json.isEmpty,
+              let raw = try? JSONSerialization.jsonObject(with: json) else {
+            return nil
+        }
+
+        // Accept both `{"profiles": [...]}` and a bare `[...]` of profiles.
+        let profilesArray: [Any]
+        if let dict = raw as? [String: Any], let arr = dict["profiles"] as? [Any] {
+            profilesArray = arr
+        } else if let arr = raw as? [Any] {
+            profilesArray = arr
+        } else {
+            return nil
+        }
+
+        var entries: [GatewayListSnapshot.ProfileEntry] = []
+        for raw in profilesArray {
+            guard let obj = raw as? [String: Any] else { continue }
+            let profile = (obj["name"] as? String)
+                ?? (obj["profile"] as? String)
+                ?? "default"
+            let isRunning: Bool
+            if let v = obj["running"] as? Bool {
+                isRunning = v
+            } else if let s = obj["state"] as? String {
+                isRunning = s.lowercased() == "running"
+            } else {
+                isRunning = false
+            }
+            let pid = obj["pid"] as? Int
+            let platforms = (obj["platforms"] as? [String])
+                ?? (obj["connected_platforms"] as? [String])
+                ?? []
+            entries.append(GatewayListSnapshot.ProfileEntry(
+                profile: profile,
+                isRunning: isRunning,
+                pid: pid,
+                platforms: platforms
+            ))
+        }
+        return GatewayListSnapshot(profiles: entries)
+    }
+
+    /// Synchronous fetch helper — call from a `Task.detached`. Returns
+    /// `nil` when the subcommand fails (pre-v0.13 host) or when the
+    /// output isn't parseable.
+    public static func fetch(context: ServerContext) -> GatewayListSnapshot? {
+        let transport = context.makeTransport()
+        let executable = context.paths.hermesBinary
+        do {
+            let result = try transport.runProcess(
+                executable: executable,
+                args: ["gateway", "list", "--json"],
+                stdin: nil,
+                timeout: 10
+            )
+            guard result.exitCode == 0 else { return nil }
+            return parse(result.stdout)
+        } catch {
+            return nil
+        }
+    }
+}

scarf/Packages/ScarfCore/Tests/ScarfCoreTests/GatewayAllowlistKindTests.swift

@@ -0,0 +1,70 @@
+import Testing
+import Foundation
+@testable import ScarfCore
+
+/// Pure mapping tests for `GatewayAllowlistKind`. Locks down the (platform →
+/// kind) table so a refactor doesn't accidentally drop a platform.
+@Suite struct GatewayAllowlistKindTests {
+
+    @Test func mapsKnownPlatformsToCorrectKind() {
+        #expect(GatewayAllowlistKind.kind(for: "slack")      == .channels)
+        #expect(GatewayAllowlistKind.kind(for: "mattermost") == .channels)
+        #expect(GatewayAllowlistKind.kind(for: "google-chat") == .channels)
+        #expect(GatewayAllowlistKind.kind(for: "telegram")   == .chats)
+        #expect(GatewayAllowlistKind.kind(for: "whatsapp")   == .chats)
+        #expect(GatewayAllowlistKind.kind(for: "matrix")     == .rooms)
+        #expect(GatewayAllowlistKind.kind(for: "dingtalk")   == .rooms)
+    }
+
+    @Test func acceptsBothGoogleChatSpellings() {
+        // // TODO(WS-5-Q1) — both spellings round-trip until Hermes confirms
+        // the wire identifier.
+        #expect(GatewayAllowlistKind.kind(for: "google-chat") == .channels)
+        #expect(GatewayAllowlistKind.kind(for: "googlechat")  == .channels)
+    }
+
+    @Test func returnsNilForPlatformsWithoutAllowlist() {
+        #expect(GatewayAllowlistKind.kind(for: "cli")            == nil)
+        #expect(GatewayAllowlistKind.kind(for: "yuanbao")        == nil)
+        #expect(GatewayAllowlistKind.kind(for: "microsoft-teams") == nil)
+        #expect(GatewayAllowlistKind.kind(for: "discord")        == nil)
+        #expect(GatewayAllowlistKind.kind(for: "signal")         == nil)
+        #expect(GatewayAllowlistKind.kind(for: "homeassistant")  == nil)
+        #expect(GatewayAllowlistKind.kind(for: "")               == nil)
+        #expect(GatewayAllowlistKind.kind(for: "unknown")        == nil)
+    }
+
+    @Test func yamlKeyMatchesHermesContract() {
+        #expect(GatewayAllowlistKind.channels.yamlKey == "allowed_channels")
+        #expect(GatewayAllowlistKind.chats.yamlKey    == "allowed_chats")
+        #expect(GatewayAllowlistKind.rooms.yamlKey    == "allowed_rooms")
+    }
+
+    @Test func nounsAreUserFacingSafe() {
+        #expect(GatewayAllowlistKind.channels.noun == "channel")
+        #expect(GatewayAllowlistKind.chats.noun    == "chat")
+        #expect(GatewayAllowlistKind.rooms.noun    == "room")
+        #expect(GatewayAllowlistKind.channels.pluralNoun == "channels")
+        #expect(GatewayAllowlistKind.chats.pluralNoun    == "chats")
+        #expect(GatewayAllowlistKind.rooms.pluralNoun    == "rooms")
+    }
+
+    @Test func placeholdersAreNonEmpty() {
+        // Smoke test — placeholder strings are advisory; we just don't want
+        // them silently emptied during a refactor.
+        #expect(!GatewayAllowlistKind.channels.inputPlaceholder.isEmpty)
+        #expect(!GatewayAllowlistKind.chats.inputPlaceholder.isEmpty)
+        #expect(!GatewayAllowlistKind.rooms.inputPlaceholder.isEmpty)
+    }
+
+    @Test func gatewayPlatformSettingsItemsForKind() {
+        let s = GatewayPlatformSettings(
+            allowedChannels: ["C01"],
+            allowedChats: ["@user"],
+            allowedRooms: ["!room:matrix.org"]
+        )
+        #expect(s.items(for: .channels) == ["C01"])
+        #expect(s.items(for: .chats)    == ["@user"])
+        #expect(s.items(for: .rooms)    == ["!room:matrix.org"])
+    }
+}

scarf/Packages/ScarfCore/Tests/ScarfCoreTests/GatewayConfigWriterTests.swift

@@ -0,0 +1,276 @@
+import Testing
+import Foundation
+@testable import ScarfCore
+
+/// Round-trip + idempotence tests for `GatewayConfigWriter.setList`. Pure
+/// `String` operations only — runs cleanly on Linux SwiftPM.
+@Suite struct GatewayConfigWriterTests {
+
+    // MARK: - Insert
+
+    @Test func setListInsertsBlockOnEmpty() {
+        let yaml = ""
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: ["C0123ABCD", "C0456EFGH"]
+        )
+        #expect(updated.contains("gateway:"))
+        #expect(updated.contains("  platforms:"))
+        #expect(updated.contains("    slack:"))
+        #expect(updated.contains("      allowed_channels:"))
+        #expect(updated.contains("- C0123ABCD"))
+        #expect(updated.contains("- C0456EFGH"))
+    }
+
+    @Test func setListAppendsScaffoldPreservingPriorContent() {
+        let yaml = """
+        model:
+          default: gpt-4o
+          provider: openai
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: ["C01"]
+        )
+        // Original content preserved verbatim at the top.
+        #expect(updated.contains("model:"))
+        #expect(updated.contains("  default: gpt-4o"))
+        #expect(updated.contains("  provider: openai"))
+        // New scaffold appended.
+        #expect(updated.contains("gateway:"))
+        #expect(updated.contains("    slack:"))
+        #expect(updated.contains("- C01"))
+    }
+
+    // MARK: - Replace
+
+    @Test func setListReplacesExistingBlock() {
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              allowed_channels:
+                - C_OLD_1
+                - C_OLD_2
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: ["C_NEW_1"]
+        )
+        #expect(updated.contains("- C_NEW_1"))
+        #expect(!updated.contains("- C_OLD_1"))
+        #expect(!updated.contains("- C_OLD_2"))
+    }
+
+    @Test func setListPreservesScalarSiblings() {
+        // The `busy_ack_enabled` scalar sibling of `allowed_channels` must
+        // stay byte-for-byte after a list-write to the same platform.
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              allowed_channels:
+                - C_OLD
+              busy_ack_enabled: false
+              gateway_restart_notification: true
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: ["C_NEW"]
+        )
+        #expect(updated.contains("- C_NEW"))
+        #expect(!updated.contains("- C_OLD"))
+        // Scalars at the same indent must survive.
+        #expect(updated.contains("busy_ack_enabled: false"))
+        #expect(updated.contains("gateway_restart_notification: true"))
+    }
+
+    @Test func setListPreservesOtherPlatformsBlocks() {
+        // Editing slack must not touch matrix.
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              allowed_channels:
+                - C_SLACK
+            matrix:
+              allowed_rooms:
+                - '!room1:matrix.org'
+                - '!room2:matrix.org'
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: ["C_SLACK_NEW"]
+        )
+        #expect(updated.contains("- C_SLACK_NEW"))
+        // Matrix block intact.
+        #expect(updated.contains("    matrix:"))
+        #expect(updated.contains("'!room1:matrix.org'"))
+        #expect(updated.contains("'!room2:matrix.org'"))
+    }
+
+    // MARK: - Remove
+
+    @Test func setListWithEmptyItemsRemovesBlock() {
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              allowed_channels:
+                - C01
+                - C02
+              busy_ack_enabled: true
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: []
+        )
+        // Block removed; sibling scalar preserved.
+        #expect(!updated.contains("allowed_channels:"))
+        #expect(!updated.contains("- C01"))
+        #expect(!updated.contains("- C02"))
+        #expect(updated.contains("busy_ack_enabled: true"))
+    }
+
+    @Test func setListWithEmptyItemsOnAbsentBlockIsNoOp() {
+        let yaml = """
+        model:
+          default: gpt-4o
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "slack",
+            key: "allowed_channels",
+            items: []
+        )
+        #expect(updated == yaml)
+    }
+
+    // MARK: - Idempotence
+
+    @Test func setListIsIdempotent() {
+        let yaml = """
+        model:
+          default: gpt-4o
+        """
+        let once = GatewayConfigWriter.setList(
+            in: yaml,
+            platform: "telegram",
+            key: "allowed_chats",
+            items: ["@alice", "@bob"]
+        )
+        let twice = GatewayConfigWriter.setList(
+            in: once,
+            platform: "telegram",
+            key: "allowed_chats",
+            items: ["@alice", "@bob"]
+        )
+        #expect(once == twice)
+    }
+
+    @Test func setListReplaceThenReplaceIsStable() {
+        let yaml = ""
+        let a = GatewayConfigWriter.setList(
+            in: yaml, platform: "matrix", key: "allowed_rooms",
+            items: ["!a:m", "!b:m"]
+        )
+        let b = GatewayConfigWriter.setList(
+            in: a, platform: "matrix", key: "allowed_rooms",
+            items: ["!c:m"]
+        )
+        #expect(b.contains("- '!c:m'"))
+        #expect(!b.contains("'!a:m'"))
+        #expect(!b.contains("'!b:m'"))
+    }
+
+    // MARK: - Quoting
+
+    @Test func setListQuotesItemsContainingColons() {
+        // Matrix room IDs contain `:` — must be single-quoted.
+        let yaml = ""
+        let updated = GatewayConfigWriter.setList(
+            in: yaml, platform: "matrix", key: "allowed_rooms",
+            items: ["!RoomId:matrix.org"]
+        )
+        #expect(updated.contains("'!RoomId:matrix.org'"))
+    }
+
+    @Test func setListQuotesItemsStartingWithAt() {
+        // Telegram usernames `@alice`.
+        let yaml = ""
+        let updated = GatewayConfigWriter.setList(
+            in: yaml, platform: "telegram", key: "allowed_chats",
+            items: ["@alice"]
+        )
+        #expect(updated.contains("'@alice'"))
+    }
+
+    @Test func setListLeavesPlainAlphanumericUnquoted() {
+        // Slack channel IDs are A-Z0-9 — emit unquoted for readability.
+        let yaml = ""
+        let updated = GatewayConfigWriter.setList(
+            in: yaml, platform: "slack", key: "allowed_channels",
+            items: ["C0123ABCD"]
+        )
+        #expect(updated.contains("- C0123ABCD"))
+        #expect(!updated.contains("'C0123ABCD'"))
+    }
+
+    @Test func setListEscapesEmbeddedSingleQuotes() {
+        let yaml = ""
+        let updated = GatewayConfigWriter.setList(
+            in: yaml, platform: "slack", key: "allowed_channels",
+            items: ["weird:'name"]
+        )
+        // Embedded single quote doubled per YAML spec.
+        #expect(updated.contains("'weird:''name'"))
+    }
+
+    // MARK: - Insertion when ancestors exist but key is absent
+
+    @Test func setListInsertsKeyUnderExistingPlatformBlock() {
+        // `gateway → platforms → slack` exists with a busy_ack_enabled
+        // scalar; `allowed_channels` is missing. Add it without disturbing
+        // the scalar sibling.
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              busy_ack_enabled: false
+        """
+        let updated = GatewayConfigWriter.setList(
+            in: yaml, platform: "slack", key: "allowed_channels",
+            items: ["C42"]
+        )
+        #expect(updated.contains("busy_ack_enabled: false"))
+        #expect(updated.contains("allowed_channels:"))
+        #expect(updated.contains("- C42"))
+    }
+
+    // MARK: - Round-trip with the YAML loader
+
+    @Test func roundTripsThroughHermesConfigYAMLLoader() {
+        // Write a list, then parse the result through HermesConfig+YAML and
+        // confirm we read back what we wrote.
+        var yaml = ""
+        yaml = GatewayConfigWriter.setList(
+            in: yaml, platform: "slack", key: "allowed_channels",
+            items: ["C01", "C02"]
+        )
+        let cfg = HermesConfig(yaml: yaml)
+        let block = cfg.gatewayPlatforms["slack"]
+        #expect(block?.allowedChannels == ["C01", "C02"])
+    }
+}

scarf/Packages/ScarfCore/Tests/ScarfCoreTests/HermesGatewayListServiceTests.swift

@@ -0,0 +1,131 @@
+import Testing
+import Foundation
+@testable import ScarfCore
+
+/// Parser tests for `hermes gateway list --json`. Pure — no transport, no
+/// process calls.
+@Suite struct HermesGatewayListServiceTests {
+
+    private func data(_ s: String) -> Data { s.data(using: .utf8)! }
+
+    @Test func parsesSingleProfileSinglePlatform() {
+        let json = data(#"""
+        {"profiles":[{"name":"default","running":true,"pid":1234,
+        "platforms":["slack","telegram"]}]}
+        """#)
+        let snap = HermesGatewayListService.parse(json)
+        #expect(snap?.profiles.count == 1)
+        #expect(snap?.profiles[0].profile == "default")
+        #expect(snap?.profiles[0].pid == 1234)
+        #expect(snap?.profiles[0].isRunning == true)
+        #expect(snap?.profiles[0].platforms == ["slack", "telegram"])
+    }
+
+    @Test func parsesMultipleProfiles() {
+        let json = data(#"""
+        {"profiles":[
+            {"name":"work","running":true,"pid":2001,"platforms":["slack"]},
+            {"name":"personal","running":false,"platforms":["telegram"]}
+        ]}
+        """#)
+        let snap = HermesGatewayListService.parse(json)
+        #expect(snap?.profiles.count == 2)
+        #expect(snap?.profiles[0].profile == "work")
+        #expect(snap?.profiles[0].isRunning == true)
+        #expect(snap?.profiles[1].profile == "personal")
+        #expect(snap?.profiles[1].isRunning == false)
+        #expect(snap?.profiles[1].pid == nil)
+    }
+
+    @Test func parsesBareArrayShape() {
+        // Tolerance for a top-level array (no `profiles` wrapper).
+        let json = data(#"""
+        [{"name":"default","running":true,"pid":42,"platforms":["discord"]}]
+        """#)
+        let snap = HermesGatewayListService.parse(json)
+        #expect(snap?.profiles.count == 1)
+        #expect(snap?.profiles[0].profile == "default")
+    }
+
+    @Test func toleratesAlternateFieldNames() {
+        // `profile` instead of `name`, `state` instead of `running`,
+        // `connected_platforms` instead of `platforms` — defensive defaults
+        // keep the parser happy if Hermes ships any of these.
+        let json = data(#"""
+        {"profiles":[{"profile":"alt","state":"running","pid":7,
+        "connected_platforms":["matrix"]}]}
+        """#)
+        let snap = HermesGatewayListService.parse(json)
+        #expect(snap?.profiles[0].profile == "alt")
+        #expect(snap?.profiles[0].isRunning == true)
+        #expect(snap?.profiles[0].platforms == ["matrix"])
+    }
+
+    @Test func returnsNilOnEmptyData() {
+        #expect(HermesGatewayListService.parse(Data()) == nil)
+    }
+
+    @Test func returnsNilOnUnparseableJSON() {
+        let json = data("not-json")
+        #expect(HermesGatewayListService.parse(json) == nil)
+    }
+
+    @Test func returnsEmptySnapshotOnEmptyProfilesArray() {
+        let json = data(#"{"profiles":[]}"#)
+        let snap = HermesGatewayListService.parse(json)
+        #expect(snap?.profiles.isEmpty == true)
+    }
+
+    @Test func toleratesUnknownKeys() {
+        // Forward-compat: a future v0.13.x Hermes adds extra fields, parser
+        // still works.
+        let json = data(#"""
+        {"profiles":[{"name":"default","running":true,"platforms":["slack"],
+        "future_field":"value","another":42}]}
+        """#)
+        let snap = HermesGatewayListService.parse(json)
+        #expect(snap?.profiles[0].profile == "default")
+    }
+
+    // MARK: - headerDigest
+
+    @Test func headerDigestEmptyProfiles() {
+        let snap = GatewayListSnapshot(profiles: [])
+        #expect(snap.headerDigest == "no profiles configured")
+    }
+
+    @Test func headerDigestSingleProfileRunning() {
+        let snap = GatewayListSnapshot(profiles: [
+            .init(profile: "default", isRunning: true, pid: 100,
+                  platforms: ["slack", "telegram"])
+        ])
+        #expect(snap.headerDigest == "default profile · running · slack, telegram")
+    }
+
+    @Test func headerDigestSingleProfileStopped() {
+        let snap = GatewayListSnapshot(profiles: [
+            .init(profile: "default", isRunning: false, pid: nil, platforms: [])
+        ])
+        #expect(snap.headerDigest == "default profile · stopped")
+    }
+
+    @Test func headerDigestMultipleProfilesSomeRunning() {
+        let snap = GatewayListSnapshot(profiles: [
+            .init(profile: "work", isRunning: true, pid: 1, platforms: ["slack"]),
+            .init(profile: "home", isRunning: false, pid: nil, platforms: ["matrix"]),
+            .init(profile: "extra", isRunning: true, pid: 2, platforms: [])
+        ])
+        // 3 profiles total, 2 running, surface first running profile's
+        // platform list as the highlight.
+        #expect(snap.headerDigest == "3 profiles (2 running) · work: slack")
+    }
+
+    @Test func headerDigestMultipleProfilesNoneRunning() {
+        let snap = GatewayListSnapshot(profiles: [
+            .init(profile: "a", isRunning: false, pid: nil, platforms: ["slack"]),
+            .init(profile: "b", isRunning: false, pid: nil, platforms: ["matrix"])
+        ])
+        // No running profile — fall back to the first profile's platforms.
+        #expect(snap.headerDigest == "2 profiles (0 running) · a: slack")
+    }
+}

scarf/Packages/ScarfCore/Tests/ScarfCoreTests/M6ConfigCronTests.swift

@@ -228,6 +228,87 @@ import Foundation
         #expect(c.timezone == "America/New_York")
     }
 
+    // MARK: - v0.13 gateway.platforms.<platform> block
+
+    @Test func gatewayPlatformsEmptyByDefault() {
+        let c = HermesConfig(yaml: "")
+        #expect(c.gatewayPlatforms.isEmpty)
+    }
+
+    @Test func parsesGatewayAllowlistsForSlack() {
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              allowed_channels:
+                - C01
+                - C02
+              busy_ack_enabled: false
+              gateway_restart_notification: true
+              slash_command_notice_ttl_seconds: 120
+        """
+        let cfg = HermesConfig(yaml: yaml)
+        let block = cfg.gatewayPlatforms["slack"]
+        #expect(block?.allowedChannels == ["C01", "C02"])
+        #expect(block?.busyAckEnabled == false)
+        #expect(block?.gatewayRestartNotification == true)
+        #expect(block?.slashCommandNoticeTTLSeconds == 120)
+    }
+
+    @Test func parsesGatewayAllowlistsForTelegramAndMatrix() {
+        let yaml = """
+        gateway:
+          platforms:
+            telegram:
+              allowed_chats:
+                - '@alice'
+                - '12345'
+            matrix:
+              allowed_rooms:
+                - '!room:matrix.org'
+        """
+        let cfg = HermesConfig(yaml: yaml)
+        #expect(cfg.gatewayPlatforms["telegram"]?.allowedChats == ["@alice", "12345"])
+        #expect(cfg.gatewayPlatforms["matrix"]?.allowedRooms == ["!room:matrix.org"])
+    }
+
+    @Test func gatewayBlockCoexistsWithLegacyPlatformBlocks() {
+        // Regression: legacy `platforms.slack.reply_to_mode` and
+        // `matrix.require_mention` must keep parsing when the new
+        // `gateway:` block is also present — no key collisions.
+        let yaml = """
+        platforms:
+          slack:
+            reply_to_mode: all
+        matrix:
+          require_mention: false
+        gateway:
+          platforms:
+            slack:
+              allowed_channels:
+                - C01
+        """
+        let cfg = HermesConfig(yaml: yaml)
+        #expect(cfg.slack.replyToMode == "all")
+        #expect(cfg.matrix.requireMention == false)
+        #expect(cfg.gatewayPlatforms["slack"]?.allowedChannels == ["C01"])
+    }
+
+    @Test func gatewayPlatformsSkipsPlatformsWithoutV013Keys() {
+        // The `gateway:` block exists but only Slack has a v0.13 key —
+        // platforms without keys must NOT appear in `gatewayPlatforms`.
+        let yaml = """
+        gateway:
+          platforms:
+            slack:
+              busy_ack_enabled: true
+        """
+        let cfg = HermesConfig(yaml: yaml)
+        #expect(cfg.gatewayPlatforms["slack"] != nil)
+        #expect(cfg.gatewayPlatforms["mattermost"] == nil)
+        #expect(cfg.gatewayPlatforms["telegram"] == nil)
+    }
+
     @Test func cronScheduleMemberwise() {
         let s = CronSchedule(
             kind: "cron",

scarf/scarf/Core/Services/HermesFileService.swift

@@ -254,6 +254,47 @@ struct HermesFileService: Sendable {
             cooldownSeconds: int("platforms.homeassistant.extra.cooldown_seconds", default: 30)
         )
 
+        // -- v0.13: per-platform Messaging Gateway settings --------------
+        // Mirrors the canonical extractor in
+        // `ScarfCore/Parsing/HermesConfig+YAML.swift`. Behaviour parity
+        // matters: both parsers must populate `gatewayPlatforms` the same
+        // way so iOS and Mac surfaces stay in lockstep.
+        // TODO(WS-5-Q2): YAML key path unverified — see the comment in the
+        // ScarfCore extractor for the resolution path.
+        let gatewayAllowlistPlatforms = [
+            "slack", "mattermost", "google-chat",
+            "telegram", "whatsapp",
+            "matrix", "dingtalk",
+        ]
+        var gatewayPlatforms: [String: GatewayPlatformSettings] = [:]
+        for platform in gatewayAllowlistPlatforms {
+            let prefix = "gateway.platforms.\(platform)."
+            let allowedChannels = lists[prefix + "allowed_channels"] ?? []
+            let allowedChats    = lists[prefix + "allowed_chats"]    ?? []
+            let allowedRooms    = lists[prefix + "allowed_rooms"]    ?? []
+            let busy            = bool(prefix + "busy_ack_enabled", default: true)
+            let restartNotice   = bool(prefix + "gateway_restart_notification",
+                                       default: false)
+            let ttl             = int(prefix + "slash_command_notice_ttl_seconds",
+                                      default: 0)
+            let isEmpty = allowedChannels.isEmpty
+                && allowedChats.isEmpty
+                && allowedRooms.isEmpty
+                && values[prefix + "busy_ack_enabled"] == nil
+                && values[prefix + "gateway_restart_notification"] == nil
+                && values[prefix + "slash_command_notice_ttl_seconds"] == nil
+            if !isEmpty {
+                gatewayPlatforms[platform] = GatewayPlatformSettings(
+                    allowedChannels: allowedChannels,
+                    allowedChats: allowedChats,
+                    allowedRooms: allowedRooms,
+                    busyAckEnabled: busy,
+                    gatewayRestartNotification: restartNotice,
+                    slashCommandNoticeTTLSeconds: ttl
+                )
+            }
+        }
+
         return HermesConfig(
             model: str("model.default", default: "unknown"),
             provider: str("model.provider", default: "unknown"),
@@ -313,7 +354,8 @@ struct HermesFileService: Sendable {
             homeAssistant: homeAssistant,
             cacheTTL: str("prompt_caching.cache_ttl", default: "5m"),
             redactionEnabled: bool("redaction.enabled", default: false),
-            runtimeMetadataFooter: bool("agent.runtime_metadata_footer", default: false)
+            runtimeMetadataFooter: bool("agent.runtime_metadata_footer", default: false),
+            gatewayPlatforms: gatewayPlatforms
         )
     }
 

scarf/scarf/Features/Gateway/ViewModels/GatewayViewModel.swift

@@ -1,7 +1,13 @@
 import Foundation
 import ScarfCore
 
-struct GatewayInfo {
+// **Local rename for v0.13 / WS-5.** The user-facing label is "Messaging
+// Gateway"; the type names mirror that. The `SidebarSection.gateway` enum
+// case + `gateway_state.json` / `gateway.log` paths intentionally stay
+// unchanged — those aren't user-facing strings, and renaming them would
+// churn unrelated callers without changing what users see.
+
+struct MessagingGatewayInfo {
     let pid: Int?
     let state: String
     let exitReason: String?
@@ -37,32 +43,48 @@ struct PendingPairing: Identifiable {
 }
 
 @Observable
-final class GatewayViewModel {
+@MainActor
+final class MessagingGatewayViewModel {
     let context: ServerContext
+    /// Capability snapshot at view-init time. Read for the v0.13 cross-
+    /// profile digest (`hasGatewayList`); other v0.13 surfaces live on
+    /// per-platform setup views. `.empty` is fine outside the per-server
+    /// `ContextBoundRoot` (Previews, smoke tests).
+    let capabilities: HermesCapabilities
 
-    init(context: ServerContext = .local) {
+    init(context: ServerContext = .local, capabilities: HermesCapabilities = .empty) {
         self.context = context
+        self.capabilities = capabilities
     }
 
-    var gateway = GatewayInfo(pid: nil, state: "unknown", exitReason: nil, startTime: nil, updatedAt: nil, platforms: [], isLoaded: false, isStale: false)
+    var gateway = MessagingGatewayInfo(pid: nil, state: "unknown", exitReason: nil, startTime: nil, updatedAt: nil, platforms: [], isLoaded: false, isStale: false)
     var approvedUsers: [PairedUser] = []
     var pendingPairings: [PendingPairing] = []
     var isLoading = false
     var actionMessage: String?
+    /// `hermes gateway list --json` snapshot. `nil` when the verb fails
+    /// (pre-v0.13 host or no profiles registered yet) — the digest row
+    /// hides itself in that case.
+    var gatewayList: GatewayListSnapshot?
 
     func load() {
         isLoading = true
         let ctx = context
+        let caps = capabilities
         Task.detached { [weak self] in
             // Two sync transport calls + two CLI invocations — substantial
             // remote latency. Detach the whole load and commit at the end.
             let status = Self.fetchGatewayStatus(context: ctx)
             let pairing = Self.fetchPairing(context: ctx)
+            let listSnap = caps.hasGatewayList
+                ? HermesGatewayListService.fetch(context: ctx)
+                : nil
             await MainActor.run { [weak self] in
                 guard let self else { return }
                 self.gateway = status
                 self.approvedUsers = pairing.approved
                 self.pendingPairings = pairing.pending
+                self.gatewayList = listSnap
                 self.isLoading = false
             }
         }
@@ -70,7 +92,7 @@ final class GatewayViewModel {
 
     /// Static form of the gateway-status walk so the detached load can call
     /// it without bouncing back to MainActor.
-    nonisolated private static func fetchGatewayStatus(context: ServerContext) -> GatewayInfo {
+    nonisolated private static func fetchGatewayStatus(context: ServerContext) -> MessagingGatewayInfo {
         let stateJSON = context.readData(context.paths.gatewayStateJSON)
         var pid: Int?
         var state = "unknown"
@@ -102,7 +124,7 @@ final class GatewayViewModel {
         let isLoaded = statusOutput.contains("service is loaded")
         let isStale = statusOutput.contains("stale")
 
-        return GatewayInfo(
+        return MessagingGatewayInfo(
             pid: pid, state: state, exitReason: exitReason,
             startTime: startTime, updatedAt: updatedAt,
             platforms: platforms, isLoaded: isLoaded, isStale: isStale

scarf/scarf/Features/Gateway/Views/GatewayView.swift

@@ -2,12 +2,24 @@ import SwiftUI
 import ScarfCore
 import ScarfDesign
 
+/// Messaging Gateway page. Routes outbound chat to Discord / Telegram /
+/// Slack / etc. — distinct from the v0.10 **Tool Gateway** (Nous Portal
+/// subscription routing for web search / image / TTS / browser), which
+/// lives under `Features/Health/`. The user-facing label here is always
+/// "Messaging Gateway"; the SwiftUI struct stays `GatewayView` because
+/// `ContentView` references it by name (rename-on-touch invariant —
+/// avoid churning unrelated callers).
 struct GatewayView: View {
-    @State private var viewModel: GatewayViewModel
+    @State private var viewModel: MessagingGatewayViewModel
     @Environment(HermesFileWatcher.self) private var fileWatcher
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
 
     init(context: ServerContext) {
-        _viewModel = State(initialValue: GatewayViewModel(context: context))
+        // Capabilities arrive via environment after init runs, so the VM
+        // is constructed with `.empty` and refreshed on first appear via
+        // `attach(capabilities:)`. Same pattern as the per-platform setup
+        // views — see `MessagingGatewayViewModel.capabilities` doc comment.
+        _viewModel = State(initialValue: MessagingGatewayViewModel(context: context))
     }
 
 
@@ -15,10 +27,15 @@ struct GatewayView: View {
         VStack(spacing: 0) {
             ScarfPageHeader(
                 "Messaging Gateway",
-                subtitle: "Outbound channel bridge — Discord, Telegram, Slack, etc."
+                subtitle: "Outbound channel bridge — Discord, Telegram, Slack, Google Chat, etc."
             )
             ScrollView {
-                VStack(alignment: .leading, spacing: 24) {
+                VStack(alignment: .leading, spacing: ScarfSpace.s4) {
+                    if let snap = viewModel.gatewayList,
+                       viewModel.capabilities.hasGatewayList,
+                       !snap.profiles.isEmpty {
+                        crossProfileDigest(snap)
+                    }
                     serviceSection
                     platformsSection
                     pairingSection
@@ -29,14 +46,58 @@ struct GatewayView: View {
         }
         .background(ScarfColor.backgroundPrimary)
         .navigationTitle("Messaging Gateway")
-        .onAppear { viewModel.load() }
+        .onAppear {
+            attachCapabilitiesIfNeeded()
+            viewModel.load()
+        }
         .onChange(of: fileWatcher.lastChangeDate) { viewModel.load() }
     }
 
+    /// Re-create the VM with the resolved capabilities the first time the
+    /// store hands us non-empty data. Same shape as `KanbanBoardView`'s
+    /// `attach` helper.
+    private func attachCapabilitiesIfNeeded() {
+        guard let store = capabilitiesStore,
+              store.capabilities.detected,
+              !viewModel.capabilities.detected else { return }
+        viewModel = MessagingGatewayViewModel(
+            context: viewModel.context,
+            capabilities: store.capabilities
+        )
+    }
+
+    // MARK: - v0.13 cross-profile digest
+
+    /// One-line summary above the gateway controls when the host is on
+    /// v0.13+ and `hermes gateway list --json` returned at least one
+    /// profile. Doubly-guarded — `hasGatewayList` AND `profiles != []`
+    /// — so a v0.13 host with no registered profiles doesn't render
+    /// an empty pill.
+    private func crossProfileDigest(_ snap: GatewayListSnapshot) -> some View {
+        HStack(spacing: ScarfSpace.s2) {
+            Image(systemName: "dot.radiowaves.left.and.right")
+                .foregroundStyle(ScarfColor.accent)
+            Text(snap.headerDigest)
+                .scarfStyle(.captionStrong)
+                .foregroundStyle(ScarfColor.foregroundPrimary)
+            Spacer()
+        }
+        .padding(.horizontal, ScarfSpace.s3)
+        .padding(.vertical, ScarfSpace.s2)
+        .background(
+            RoundedRectangle(cornerRadius: ScarfRadius.md, style: .continuous)
+                .fill(ScarfColor.backgroundSecondary)
+        )
+        .overlay(
+            RoundedRectangle(cornerRadius: ScarfRadius.md, style: .continuous)
+                .strokeBorder(ScarfColor.border, lineWidth: 1)
+        )
+    }
+
     // MARK: - Service
 
     private var serviceSection: some View {
-        VStack(alignment: .leading, spacing: 12) {
+        VStack(alignment: .leading, spacing: ScarfSpace.s3) {
             HStack {
                 Text("Service")
                     .font(.headline)
@@ -46,15 +107,20 @@ struct GatewayView: View {
                         .font(.caption)
                         .foregroundStyle(.secondary)
                 }
-                HStack(spacing: 8) {
+                HStack(spacing: ScarfSpace.s2) {
                     Button("Start") { viewModel.startGateway() }
+                        .buttonStyle(ScarfPrimaryButton())
+                        .controlSize(.small)
                     Button("Stop") { viewModel.stopGateway() }
+                        .buttonStyle(ScarfSecondaryButton())
+                        .controlSize(.small)
                     Button("Restart") { viewModel.restartGateway() }
+                        .buttonStyle(ScarfSecondaryButton())
+                        .controlSize(.small)
                 }
-                .controlSize(.small)
             }
 
-            HStack(spacing: 16) {
+            HStack(spacing: ScarfSpace.s3) {
                 StatusBadge(
                     label: viewModel.gateway.state,
                     isActive: viewModel.gateway.state == "running"
@@ -97,7 +163,7 @@ struct GatewayView: View {
     // MARK: - Platforms
 
     private var platformsSection: some View {
-        VStack(alignment: .leading, spacing: 8) {
+        VStack(alignment: .leading, spacing: ScarfSpace.s2) {
             Text("Platforms")
                 .font(.headline)
             if viewModel.gateway.platforms.isEmpty {
@@ -105,7 +171,7 @@ struct GatewayView: View {
                     .font(.caption)
                     .foregroundStyle(.secondary)
             } else {
-                HStack(spacing: 12) {
+                HStack(spacing: ScarfSpace.s3) {
                     ForEach(viewModel.gateway.platforms) { platform in
                         VStack(spacing: 6) {
                             Image(systemName: platform.icon)
@@ -119,9 +185,9 @@ struct GatewayView: View {
                             )
                         }
                         .frame(maxWidth: .infinity)
-                        .padding(12)
+                        .padding(ScarfSpace.s3)
                         .background(.quaternary.opacity(0.5))
-                        .clipShape(RoundedRectangle(cornerRadius: 8))
+                        .clipShape(RoundedRectangle(cornerRadius: ScarfRadius.md))
                     }
                 }
             }
@@ -131,12 +197,12 @@ struct GatewayView: View {
     // MARK: - Pairing
 
     private var pairingSection: some View {
-        VStack(alignment: .leading, spacing: 12) {
+        VStack(alignment: .leading, spacing: ScarfSpace.s3) {
             Text("Paired Users")
                 .font(.headline)
 
             if !viewModel.pendingPairings.isEmpty {
-                VStack(alignment: .leading, spacing: 8) {
+                VStack(alignment: .leading, spacing: ScarfSpace.s2) {
                     Label("Pending Approvals", systemImage: "clock.badge.questionmark")
                         .font(.caption.bold())
                         .foregroundStyle(.orange)
@@ -150,12 +216,12 @@ struct GatewayView: View {
                                 viewModel.approvePairing(platform: pending.platform, code: pending.code)
                             }
                             .controlSize(.small)
-                            .buttonStyle(.borderedProminent)
+                            .buttonStyle(ScarfPrimaryButton())
                         }
                         .font(.caption)
-                        .padding(8)
+                        .padding(ScarfSpace.s2)
                         .background(.orange.opacity(0.1))
-                        .clipShape(RoundedRectangle(cornerRadius: 6))
+                        .clipShape(RoundedRectangle(cornerRadius: ScarfRadius.sm))
                     }
                 }
             }
@@ -182,9 +248,9 @@ struct GatewayView: View {
                         }
                         .controlSize(.small)
                     }
-                    .padding(8)
+                    .padding(ScarfSpace.s2)
                     .background(.quaternary.opacity(0.3))
-                    .clipShape(RoundedRectangle(cornerRadius: 6))
+                    .clipShape(RoundedRectangle(cornerRadius: ScarfRadius.sm))
                 }
             }
         }

scarf/scarf/Features/Platforms/ViewModels/PlatformSetup/GatewayBehaviorViewModel.swift

@@ -0,0 +1,140 @@
+import Foundation
+import ScarfCore
+import os
+
+/// View-model for the v0.13 Messaging Gateway behavior subsection composed
+/// into each per-platform setup view. Owns the four v0.13 controls
+/// (allowlist + three behavior toggles) so the existing per-platform VMs
+/// don't grow another set of fields.
+///
+/// Capability-gated. Pre-v0.13 hosts skip the entire subsection (the
+/// owning view returns `EmptyView` when none of the v0.13 flags is on),
+/// so this VM never has its `save()` called against a host that can't
+/// honor it.
+@Observable
+@MainActor
+final class GatewayBehaviorViewModel {
+    private static let logger = Logger(subsystem: "com.scarf", category: "GatewayBehavior")
+
+    let platform: String
+    let context: ServerContext
+    let capabilities: HermesCapabilities
+    /// Allowlist kind for this platform, or `nil` for platforms without
+    /// an allowlist surface (Discord, Signal, etc. — `GatewayBehaviorSection`
+    /// short-circuits before instantiating this VM in that case, but the
+    /// field is `nil` for safety).
+    let kind: GatewayAllowlistKind?
+
+    // Allowlist
+    var items: [String] = []
+
+    // Behavior toggles
+    var busyAckEnabled: Bool = true
+    var gatewayRestartNotification: Bool = false
+    var slashCommandNoticeTTLSeconds: Int = 0
+
+    var message: String?
+    var isSaving: Bool = false
+
+    init(
+        platform: String,
+        capabilities: HermesCapabilities,
+        context: ServerContext = .local
+    ) {
+        self.platform = platform
+        self.capabilities = capabilities
+        self.context = context
+        self.kind = GatewayAllowlistKind.kind(for: platform)
+    }
+
+    /// Hydrate from `~/.hermes/config.yaml`. Called from the section's
+    /// `.onAppear`. Empty when the platform has no `gateway:` block in
+    /// the file — defaults match v0.13 server-side defaults so the form
+    /// looks identical to a fresh-install host.
+    func load() {
+        let cfg = HermesFileService(context: context).loadConfig()
+        let block = cfg.gatewayPlatforms[platform] ?? .empty
+        if let kind {
+            switch kind {
+            case .channels: items = block.allowedChannels
+            case .chats:    items = block.allowedChats
+            case .rooms:    items = block.allowedRooms
+            }
+        } else {
+            items = []
+        }
+        busyAckEnabled              = block.busyAckEnabled
+        gatewayRestartNotification  = block.gatewayRestartNotification
+        slashCommandNoticeTTLSeconds = block.slashCommandNoticeTTLSeconds
+    }
+
+    /// Persist edits in two phases:
+    ///
+    /// 1. **Allowlist write** via `GatewayConfigWriter.saveList` — direct
+    ///    YAML edit, since `hermes config set` can't write list values.
+    ///    Skipped when the platform has no `kind` (no allowlist surface)
+    ///    or the host doesn't advertise `hasGatewayAllowlists`.
+    /// 2. **Scalar saves** via `PlatformSetupHelpers.saveForm` for the
+    ///    three v0.13 behavior toggles. Each gated on its own capability
+    ///    flag; the TTL field rides on the `hasGatewayBusyAckToggle ‖
+    ///    hasGatewayRestartNotification` proxy (see WS-5 plan §Open Questions
+    ///    Q5 + WS-1 Decision F).
+    func save() {
+        isSaving = true
+        defer {
+            isSaving = false
+            DispatchQueue.main.asyncAfter(deadline: .now() + 3) { [weak self] in
+                self?.message = nil
+            }
+        }
+
+        // Step 1: list write via direct YAML edit. Detached so the SCP
+        // round-trip on remote hosts doesn't block MainActor — local
+        // writes are still cheap, but the same posture works for both.
+        if let kind, capabilities.hasGatewayAllowlists {
+            let trimmed = items
+                .map { $0.trimmingCharacters(in: .whitespaces) }
+                .filter { !$0.isEmpty }
+            let ok = GatewayConfigWriter.saveList(
+                context: context,
+                platform: platform,
+                key: kind.yamlKey,
+                items: trimmed
+            )
+            if !ok {
+                Self.logger.warning("GatewayConfigWriter.saveList failed for \(self.platform, privacy: .public)")
+                message = "Failed to write allowlist to config.yaml"
+                return
+            }
+        }
+
+        // Step 2: scalar saves via `hermes config set`.
+        var configKV: [String: String] = [:]
+        let prefix = "gateway.platforms.\(platform)."
+        if capabilities.hasGatewayBusyAckToggle {
+            configKV[prefix + "busy_ack_enabled"] =
+                PlatformSetupHelpers.envBool(busyAckEnabled)
+        }
+        if capabilities.hasGatewayRestartNotification {
+            configKV[prefix + "gateway_restart_notification"] =
+                PlatformSetupHelpers.envBool(gatewayRestartNotification)
+        }
+        // TTL field rides on either of the v0.13 toggles being available —
+        // proxy gating per WS-1 Decision F + WS-5 Q5. // TODO(WS-5-Q5)
+        if capabilities.hasGatewayBusyAckToggle
+            || capabilities.hasGatewayRestartNotification {
+            configKV[prefix + "slash_command_notice_ttl_seconds"] =
+                String(slashCommandNoticeTTLSeconds)
+        }
+
+        if configKV.isEmpty {
+            message = "Allowlist saved — restart gateway to apply"
+            return
+        }
+
+        let result = PlatformSetupHelpers.saveForm(
+            context: context, envPairs: [:], configKV: configKV
+        )
+        message = result
+    }
+}

scarf/scarf/Features/Platforms/Views/PlatformSetup/Components/AllowlistEditor.swift

@@ -0,0 +1,103 @@
+import SwiftUI
+import ScarfCore
+import ScarfDesign
+
+/// Reusable list-of-strings editor for v0.13 cross-platform allowlists.
+/// Shape: a vertical stack of rows, each with a delete glyph; an "Add row"
+/// button at the bottom appends an empty entry.
+///
+/// Stateless — binds to the parent VM's `items` array. The VM owns
+/// persistence and change tracking; this view is pure presentation.
+struct AllowlistEditor: View {
+    @Binding var items: [String]
+    let kind: GatewayAllowlistKind
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: ScarfSpace.s2) {
+            HStack {
+                Text("Allowed \(kind.pluralNoun)")
+                    .scarfStyle(.caption)
+                    .foregroundStyle(ScarfColor.foregroundMuted)
+                Spacer()
+                Text(itemsCountLabel)
+                    .scarfStyle(.caption)
+                    .foregroundStyle(ScarfColor.foregroundFaint)
+            }
+
+            if items.isEmpty {
+                Text("No restrictions — agent responds in any \(kind.noun).")
+                    .scarfStyle(.caption)
+                    .foregroundStyle(ScarfColor.foregroundFaint)
+                    .padding(.vertical, ScarfSpace.s2)
+            } else {
+                VStack(spacing: 4) {
+                    ForEach(Array(items.enumerated()), id: \.offset) { idx, _ in
+                        AllowlistRow(
+                            value: Binding(
+                                get: { items[safe: idx] ?? "" },
+                                set: { newValue in
+                                    guard idx < items.count else { return }
+                                    items[idx] = newValue
+                                }
+                            ),
+                            placeholder: kind.inputPlaceholder,
+                            onDelete: {
+                                guard idx < items.count else { return }
+                                items.remove(at: idx)
+                            }
+                        )
+                    }
+                }
+            }
+
+            HStack {
+                Button {
+                    items.append("")
+                } label: {
+                    Label("Add \(kind.noun)", systemImage: "plus.circle")
+                        .font(.caption)
+                }
+                .buttonStyle(.borderless)
+                Spacer()
+            }
+        }
+        .padding(.horizontal, ScarfSpace.s3)
+        .padding(.vertical, ScarfSpace.s2)
+    }
+
+    private var itemsCountLabel: String {
+        let nonEmpty = items.filter { !$0.trimmingCharacters(in: .whitespaces).isEmpty }.count
+        if nonEmpty == 0 { return "0 \(kind.pluralNoun)" }
+        if nonEmpty == 1 { return "1 \(kind.noun)" }
+        return "\(nonEmpty) \(kind.pluralNoun)"
+    }
+}
+
+private struct AllowlistRow: View {
+    @Binding var value: String
+    let placeholder: String
+    let onDelete: () -> Void
+
+    var body: some View {
+        HStack(spacing: ScarfSpace.s2) {
+            TextField(placeholder, text: $value)
+                .textFieldStyle(.roundedBorder)
+                .font(ScarfFont.monoSmall)
+            Button {
+                onDelete()
+            } label: {
+                Image(systemName: "minus.circle.fill")
+                    .foregroundStyle(ScarfColor.danger)
+            }
+            .buttonStyle(.plain)
+            .help("Remove")
+        }
+    }
+}
+
+private extension Array {
+    subscript(safe index: Int) -> Element? {
+        guard index >= 0, index < count else { return nil }
+        return self[index]
+    }
+}

scarf/scarf/Features/Platforms/Views/PlatformSetup/Components/GatewayBehaviorSection.swift

@@ -0,0 +1,96 @@
+import SwiftUI
+import ScarfCore
+import ScarfDesign
+
+/// v0.13 Messaging Gateway behavior subsection composed into each per-
+/// platform setup view (Slack, Mattermost, Telegram, WhatsApp, Matrix,
+/// Google Chat). Owns its own `@State` view-model so the existing per-
+/// platform VMs don't grow another set of fields.
+///
+/// **Capability gating.** Hides itself entirely on pre-v0.13 hosts
+/// (returns `EmptyView` when none of the three v0.13 flags is on). Each
+/// internal control gates on its own flag, so a host that gains, say,
+/// `hasGatewayAllowlists` but not `hasGatewayBusyAckToggle` still gets
+/// the allowlist editor with the toggles hidden.
+struct GatewayBehaviorSection: View {
+    let platform: String
+    let capabilities: HermesCapabilities
+    let context: ServerContext
+
+    @State private var viewModel: GatewayBehaviorViewModel
+
+    init(platform: String, capabilities: HermesCapabilities, context: ServerContext) {
+        self.platform = platform
+        self.capabilities = capabilities
+        self.context = context
+        _viewModel = State(initialValue: GatewayBehaviorViewModel(
+            platform: platform,
+            capabilities: capabilities,
+            context: context
+        ))
+    }
+
+    var body: some View {
+        // Pre-v0.13 host — hide the entire subsection so the existing
+        // platform forms look unchanged. Critical regression invariant
+        // per WS-5 plan §"How to test" #1.
+        if !capabilities.hasGatewayAllowlists
+            && !capabilities.hasGatewayBusyAckToggle
+            && !capabilities.hasGatewayRestartNotification {
+            EmptyView()
+        } else {
+            content
+        }
+    }
+
+    private var content: some View {
+        VStack(alignment: .leading, spacing: ScarfSpace.s3) {
+            SettingsSection(title: "Gateway behavior (v0.13+)", icon: "dot.radiowaves.left.and.right") {
+                if capabilities.hasGatewayAllowlists,
+                   let kind = viewModel.kind {
+                    AllowlistEditor(
+                        items: $viewModel.items,
+                        kind: kind
+                    )
+                }
+                if capabilities.hasGatewayBusyAckToggle {
+                    ToggleRow(
+                        label: "Send 'Agent is working…' ack",
+                        isOn: viewModel.busyAckEnabled
+                    ) { viewModel.busyAckEnabled = $0 }
+                }
+                if capabilities.hasGatewayRestartNotification {
+                    ToggleRow(
+                        label: "Post 'Gateway restarted' notice on boot",
+                        isOn: viewModel.gatewayRestartNotification
+                    ) { viewModel.gatewayRestartNotification = $0 }
+                }
+                // TTL field rides on either v0.13 toggle being available
+                // — proxy gating per WS-1 Decision F. // TODO(WS-5-Q5)
+                if capabilities.hasGatewayBusyAckToggle
+                    || capabilities.hasGatewayRestartNotification {
+                    StepperRow(
+                        label: "Auto-delete slash-command notices (s)",
+                        value: viewModel.slashCommandNoticeTTLSeconds,
+                        range: 0...3600,
+                        step: 5
+                    ) { viewModel.slashCommandNoticeTTLSeconds = $0 }
+                }
+            }
+
+            HStack {
+                if let msg = viewModel.message {
+                    Label(msg, systemImage: "checkmark.circle.fill")
+                        .font(.caption)
+                        .foregroundStyle(.green)
+                }
+                Spacer()
+                Button("Save behavior") { viewModel.save() }
+                    .buttonStyle(ScarfPrimaryButton())
+                    .controlSize(.small)
+                    .disabled(viewModel.isSaving)
+            }
+        }
+        .onAppear { viewModel.load() }
+    }
+}

scarf/scarf/Features/Platforms/Views/PlatformSetup/MatrixSetupView.swift

@@ -4,7 +4,13 @@ import ScarfDesign
 
 struct MatrixSetupView: View {
     @State private var viewModel: MatrixSetupViewModel
-    init(context: ServerContext) { _viewModel = State(initialValue: MatrixSetupViewModel(context: context)) }
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
+    let context: ServerContext
+
+    init(context: ServerContext) {
+        self.context = context
+        _viewModel = State(initialValue: MatrixSetupViewModel(context: context))
+    }
 
 
     var body: some View {
@@ -45,6 +51,13 @@ struct MatrixSetupView: View {
             }
 
             saveBar
+
+            // v0.13 Messaging Gateway behavior — self-hides on pre-v0.13.
+            GatewayBehaviorSection(
+                platform: "matrix",
+                capabilities: capabilitiesStore?.capabilities ?? .empty,
+                context: context
+            )
         }
         .onAppear { viewModel.load() }
     }

scarf/scarf/Features/Platforms/Views/PlatformSetup/MattermostSetupView.swift

@@ -4,7 +4,13 @@ import ScarfDesign
 
 struct MattermostSetupView: View {
     @State private var viewModel: MattermostSetupViewModel
-    init(context: ServerContext) { _viewModel = State(initialValue: MattermostSetupViewModel(context: context)) }
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
+    let context: ServerContext
+
+    init(context: ServerContext) {
+        self.context = context
+        _viewModel = State(initialValue: MattermostSetupViewModel(context: context))
+    }
 
 
     var body: some View {
@@ -28,6 +34,13 @@ struct MattermostSetupView: View {
             }
 
             saveBar
+
+            // v0.13 Messaging Gateway behavior — self-hides on pre-v0.13.
+            GatewayBehaviorSection(
+                platform: "mattermost",
+                capabilities: capabilitiesStore?.capabilities ?? .empty,
+                context: context
+            )
         }
         .onAppear { viewModel.load() }
     }

scarf/scarf/Features/Platforms/Views/PlatformSetup/SlackSetupView.swift

@@ -4,7 +4,13 @@ import ScarfDesign
 
 struct SlackSetupView: View {
     @State private var viewModel: SlackSetupViewModel
-    init(context: ServerContext) { _viewModel = State(initialValue: SlackSetupViewModel(context: context)) }
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
+    let context: ServerContext
+
+    init(context: ServerContext) {
+        self.context = context
+        _viewModel = State(initialValue: SlackSetupViewModel(context: context))
+    }
 
 
     var body: some View {
@@ -30,6 +36,13 @@ struct SlackSetupView: View {
             }
 
             saveBar
+
+            // v0.13 Messaging Gateway behavior — self-hides on pre-v0.13.
+            GatewayBehaviorSection(
+                platform: "slack",
+                capabilities: capabilitiesStore?.capabilities ?? .empty,
+                context: context
+            )
         }
         .onAppear { viewModel.load() }
     }

scarf/scarf/Features/Platforms/Views/PlatformSetup/TelegramSetupView.swift

@@ -4,7 +4,13 @@ import ScarfDesign
 
 struct TelegramSetupView: View {
     @State private var viewModel: TelegramSetupViewModel
-    init(context: ServerContext) { _viewModel = State(initialValue: TelegramSetupViewModel(context: context)) }
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
+    let context: ServerContext
+
+    init(context: ServerContext) {
+        self.context = context
+        _viewModel = State(initialValue: TelegramSetupViewModel(context: context))
+    }
 
 
     var body: some View {
@@ -29,6 +35,13 @@ struct TelegramSetupView: View {
             }
 
             saveBar
+
+            // v0.13 Messaging Gateway behavior — self-hides on pre-v0.13.
+            GatewayBehaviorSection(
+                platform: "telegram",
+                capabilities: capabilitiesStore?.capabilities ?? .empty,
+                context: context
+            )
         }
         .onAppear { viewModel.load() }
     }

scarf/scarf/Features/Platforms/Views/PlatformSetup/WhatsAppSetupView.swift

@@ -4,7 +4,13 @@ import ScarfDesign
 
 struct WhatsAppSetupView: View {
     @State private var viewModel: WhatsAppSetupViewModel
-    init(context: ServerContext) { _viewModel = State(initialValue: WhatsAppSetupViewModel(context: context)) }
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
+    let context: ServerContext
+
+    init(context: ServerContext) {
+        self.context = context
+        _viewModel = State(initialValue: WhatsAppSetupViewModel(context: context))
+    }
 
 
     var body: some View {
@@ -29,6 +35,14 @@ struct WhatsAppSetupView: View {
             }
 
             saveBar
+
+            // v0.13 Messaging Gateway behavior — self-hides on pre-v0.13.
+            GatewayBehaviorSection(
+                platform: "whatsapp",
+                capabilities: capabilitiesStore?.capabilities ?? .empty,
+                context: context
+            )
+
             Divider()
             pairingSection
         }

scarf/scarf/Features/Platforms/Views/PlatformsView.swift

@@ -5,6 +5,33 @@ import ScarfDesign
 struct PlatformsView: View {
     @State private var viewModel: PlatformsViewModel
     @Environment(HermesFileWatcher.self) private var fileWatcher
+    @Environment(\.hermesCapabilities) private var capabilitiesStore
+
+    /// Capabilities resolved at view-eval time. Defaults to `.empty` outside
+    /// the per-server `ContextBoundRoot`. Used to filter `KnownPlatforms.all`
+    /// for v0.13-only entries (Google Chat) — see `visiblePlatforms` for
+    /// the deliberate asymmetry: pre-v0.12 hosts still see Yuanbao + Teams
+    /// unfiltered, by design.
+    private var capabilities: HermesCapabilities {
+        capabilitiesStore?.capabilities ?? .empty
+    }
+
+    /// Capability-filtered platform list. Today only **Google Chat** is
+    /// gated — Yuanbao and Microsoft Teams stay unfiltered to avoid
+    /// changing v0.12 host UX in a v0.13 work-stream (WS-5 plan §Q4).
+    /// If we later decide to gate the v0.12 platforms too, add their
+    /// flags here; the `default: true` arm keeps every other platform
+    /// visible.
+    private var visiblePlatforms: [HermesToolPlatform] {
+        KnownPlatforms.all.filter { p in
+            switch p.name {
+            case "google-chat", "googlechat":
+                return capabilities.hasGoogleChatPlatform
+            default:
+                return true
+            }
+        }
+    }
 
     init(context: ServerContext) {
         _viewModel = State(initialValue: PlatformsViewModel(context: context))
@@ -40,12 +67,12 @@ struct PlatformsView: View {
             List(selection: Binding(
                 get: { viewModel.selected.name },
                 set: { name in
-                    if let p = viewModel.platforms.first(where: { $0.name == name }) {
+                    if let p = visiblePlatforms.first(where: { $0.name == name }) {
                         viewModel.selected = p
                     }
                 }
             )) {
-                ForEach(viewModel.platforms) { platform in
+                ForEach(visiblePlatforms) { platform in
                     HStack(spacing: 8) {
                         Image(systemName: KnownPlatforms.icon(for: platform.name))
                             .frame(width: 20)
@@ -149,6 +176,7 @@ struct PlatformsView: View {
         case "webhook":        WebhookSetupView(context: ctx)
         case "yuanbao":        yuanbaoPanel
         case "microsoft-teams": microsoftTeamsPanel
+        case "google-chat", "googlechat": googleChatPanel
         default:
             SettingsSection(title: LocalizedStringKey(viewModel.selected.displayName), icon: KnownPlatforms.icon(for: viewModel.selected.name)) {
                 ReadOnlyRow(label: "Setup", value: "No setup form for this platform yet.")
@@ -180,6 +208,27 @@ struct PlatformsView: View {
         }
     }
 
+    /// Hermes v0.13 — Google Chat is the 20th gateway platform. Like
+    /// Yuanbao + Microsoft Teams, the auth dance is OAuth-style and
+    /// lives outside Scarf, so the panel surfaces the setup verb rather
+    /// than a per-field form. The `GatewayBehaviorSection` below it picks
+    /// up the v0.13 allowlist + behavior toggles, capability-gated.
+    @ViewBuilder
+    private var googleChatPanel: some View {
+        VStack(alignment: .leading, spacing: ScarfSpace.s3) {
+            SettingsSection(title: "Google Chat", icon: KnownPlatforms.icon(for: "google-chat")) {
+                ReadOnlyRow(label: "Type", value: "Generic env-driven gateway adapter (v0.13+)")
+                ReadOnlyRow(label: "Setup", value: "Run `hermes setup` and select Google Chat to walk the OAuth flow.")
+                ReadOnlyRow(label: "Configured", value: viewModel.hasConfigBlock(for: viewModel.selected) ? "Yes" : "No")
+            }
+            GatewayBehaviorSection(
+                platform: "google-chat",
+                capabilities: capabilities,
+                context: viewModel.context
+            )
+        }
+    }
+
     private var cliPanel: some View {
         SettingsSection(title: "CLI", icon: "terminal") {
             ReadOnlyRow(label: "Scope", value: "Local terminal sessions")

scarf/scarf/Features/Skills/Views/SkillsView.swift

@@ -307,6 +307,16 @@ struct SkillsView: View {
                        case .missing(let hint) = designMdNpxStatus {
                         designMdNpxBanner(hint: hint)
                     }
+                    // v0.13 `[[as_document]]` directive — informational
+                    // only. Rendered when the skill body contains the
+                    // marker AND the host advertises Google Chat support
+                    // (cheap proxy: the directive shipped in v0.13
+                    // alongside Google Chat — see WS-5 plan §Q5/Q6).
+                    if (capabilitiesStore?.capabilities.hasGoogleChatPlatform ?? false),
+                       skillContentMentionsAsDocument {
+                        asDocumentInfoRow
+                    }
+
                     // v2.5 SKILL.md frontmatter chips. Render only the
                     // sections that are populated — old skills without
                     // this metadata show no extra rows.
@@ -402,6 +412,39 @@ struct SkillsView: View {
         }
     }
 
+    /// Returns true when the loaded skill body contains the v0.13
+    /// `[[as_document]]` directive. Substring scan over `skillContent`
+    /// — `[[as_document]]` is a literal token Hermes pattern-matches at
+    /// runtime, not a frontmatter key, so the body is the right place
+    /// to look. // TODO(WS-5-Q6): if Hermes ever moves the directive
+    /// into frontmatter, switch to `SkillFrontmatterParser` instead.
+    private var skillContentMentionsAsDocument: Bool {
+        viewModel.skillContent.contains("[[as_document]]")
+    }
+
+    /// Compact informational row about the `[[as_document]]` directive.
+    /// Does not block any action — it's a label so users understand why
+    /// images in the skill might land as document attachments on certain
+    /// platforms (Google Chat, Microsoft Teams) rather than inline.
+    private var asDocumentInfoRow: some View {
+        HStack(alignment: .top, spacing: 8) {
+            Image(systemName: "doc.badge.gearshape")
+                .foregroundStyle(.blue)
+            VStack(alignment: .leading, spacing: 2) {
+                Text("Document-attachment directive present (v0.13+)")
+                    .font(.caption.bold())
+                Text("Media in this skill marked with `[[as_document]]` is sent as document attachments instead of inline images on platforms that distinguish (Google Chat, Microsoft Teams).")
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+                    .fixedSize(horizontal: false, vertical: true)
+            }
+        }
+        .padding(10)
+        .frame(maxWidth: .infinity, alignment: .leading)
+        .background(.blue.opacity(0.08))
+        .clipShape(RoundedRectangle(cornerRadius: 8))
+    }
+
     /// Yellow banner surfaced on the design-md skill detail when the
     /// host's `npx` probe came back missing. Reuses the same color
     /// language as the missing-config banner.