Tool Call Semantics Alignment

Nucleic-Session: B5E370C3-4764-47E1-95D3-A36B4AAB8AC6

NucleicRemote/NucleicRemote/Views/Transcript/TranscriptProjection.swift

@@ -4,8 +4,10 @@ import NucleicProtocol
 /// One render-ready row, folded from the raw `[AgentEvent]` stream. The phone subscribes at
 /// `.full`, so it receives streaming text deltas and every step of a tool call's lifecycle;
 /// this projection coalesces those into the same shapes the Mac transcript shows — one bubble
-/// per message, one card per tool call — so the view layer stays dumb. (Mirrors the desktop's
+/// per message, one card per tool call, a single contiguous block for a run of consecutive
-/// `TranscriptProjection` at phone fidelity.)
+/// calls, and a subagent spawn carrying its own nested activity — so the view layer stays dumb.
+/// (Mirrors the desktop's `TranscriptProjection` at phone fidelity, including its event
+/// partitioning, tool-run coalescing, and subagent nesting.)
 struct TranscriptItem: Identifiable, Equatable {
     let id: String
     /// The seq of the first event that created this item — stable scroll anchor + ordering.
@@ -17,9 +19,14 @@ struct TranscriptItem: Identifiable, Equatable {
     enum Kind: Equatable {
         case message(role: Role, text: String)
         case thinking(text: String)
+        /// A single tool call. A subagent spawn (`Task`/`Agent`) carries its inner activity in
+        /// `group.children` and renders as the gold subagent card; every other tool is a plain
+        /// collapsible card.
         case tool(ToolGroup)
-        /// A `Task`/`Agent` spawn — rendered as the gold Orchestra card.
+        /// A run of ≥2 consecutive tool calls coalesced into one contiguous block — the phone
-        case orchestration(ToolGroup)
+        /// echo of the Mac's `.toolGroup`. A run made entirely of subagent spawns is a
+        /// multi-agent fan-out (the gold orchestration card); any other run is a tool block.
+        case toolBlock([ToolGroup])
         case sessionStarted(model: String, cwd: String)
         case usage(Usage)
         case rateLimit(RateLimit)
@@ -30,6 +37,17 @@ struct TranscriptItem: Identifiable, Equatable {
         case note(text: String, icon: String?, lockEvent: Bool)
         case raw(type: String, body: String)
     }
+
+    /// A row that draws nothing visible — an empty/redacted `.thinking` block (the agent streams
+    /// a finalized empty thinking item whenever the reasoning itself is redacted). Held aside
+    /// during tool-run coalescing so it doesn't split an otherwise-contiguous run of calls into
+    /// two cards with a gap. Mirrors the desktop projection's `rendersNothing`.
+    var rendersNothing: Bool {
+        if case .thinking(let text) = kind {
+            return text.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+        }
+        return false
+    }
 }
 
 /// One tool call's coalesced lifecycle: start → input deltas → complete → result → file changes.
@@ -42,6 +60,10 @@ struct ToolGroup: Equatable {
     var finished: Bool = false
     /// Paths the call touched (from `fileChange` events tagged with this tool call).
     var fileChanges: [FilePatch] = []
+    /// For a subagent spawn (`Task`/`Agent`): the inner activity it produced — its own tool
+    /// calls, thinking, and prose — projected the same way and nested here, so the card can show
+    /// its live Read/Bash/Edit stream. Empty for every ordinary (non-subagent) tool.
+    var children: [TranscriptItem] = []
 
     struct FilePatch: Equatable { let path: String; let change: FileChange.ChangeKind }
 
@@ -51,9 +73,167 @@ struct ToolGroup: Equatable {
 }
 
 enum TranscriptProjection {
+    /// How deep subagent nesting is followed before deeper descendants are left unattached — a
+    /// safety bound on the recursion (a subagent spawning a subagent spawning a subagent …), far
+    /// past any real fan-out depth. Mirrors the desktop projection.
+    private static let maxSubagentDepth = 4
+
     /// Fold the raw event stream into render rows. `showRaw` surfaces unrecognized passthrough
     /// events (debug); `showLockEvents` keeps file-lock lifecycle notes (off = quieter feed).
+    ///
+    /// Work that happens *inside* a spawned subagent arrives in this same stream tagged with the
+    /// parent `Task`'s id (`parentToolCallID`). We partition events by which subagent (if any)
+    /// owns them, project the main agent's own events at the top level, and recursively project
+    /// each subagent's events into the `children` of its spawn — so a subagent's inner work nests
+    /// under its card instead of leaking (and interleaving) into the main transcript.
     static func build(_ events: [AgentEvent], showRaw: Bool, showLockEvents: Bool) -> [TranscriptItem] {
+        let (topLevel, byParent) = partition(events)
+        return project(topLevel, byParent: byParent, depth: 0, showRaw: showRaw, showLockEvents: showLockEvents)
+    }
+
+    // MARK: - Subagent partitioning
+
+    /// Split a scope's events into the main agent's own (`topLevel`) and each subagent's, keyed by
+    /// the spawning `Task`'s id.
+    private static func partition(_ events: [AgentEvent])
+        -> (topLevel: [AgentEvent], byParent: [String: [AgentEvent]])
+    {
+        let parentOf = toolParentMap(events)
+        var topLevel: [AgentEvent] = []
+        var byParent: [String: [AgentEvent]] = [:]
+        for event in events {
+            if let owner = subagentOwner(of: event, parentOf: parentOf) {
+                byParent[owner, default: []].append(event)
+            } else {
+                topLevel.append(event)
+            }
+        }
+        return (topLevel, byParent)
+    }
+
+    /// Maps each tool-call id to its parent subagent's id, built from the call start/complete
+    /// events. A tool *result* or *file change* names only a tool id, so it inherits its subagent
+    /// scope from the call it belongs to via this map.
+    private static func toolParentMap(_ events: [AgentEvent]) -> [String: String] {
+        var map: [String: String] = [:]
+        for event in events {
+            switch event.kind {
+            case .toolCallStarted(let call), .toolCallCompleted(let call):
+                if let parent = call.parentToolCallID { map[call.toolCallID] = parent }
+            default:
+                break
+            }
+        }
+        return map
+    }
+
+    /// The id of the subagent whose scope this event belongs to, or nil for the main agent's own
+    /// turn. Tool calls and the subagent's prose/thinking carry the parent link directly; a tool
+    /// result or file change inherits it from the call it references.
+    private static func subagentOwner(of event: AgentEvent, parentOf: [String: String]) -> String? {
+        switch event.kind {
+        case .toolCallStarted(let call), .toolCallCompleted(let call):
+            return call.parentToolCallID
+        case .toolResult(let result):
+            return parentOf[result.toolCallID]
+        case .fileChange(let change):
+            return change.toolCallID.flatMap { parentOf[$0] }
+        case .assistantText(let chunk), .thinking(let chunk):
+            return chunk.parentToolCallID
+        default:
+            return nil
+        }
+    }
+
+    /// Projects one scope's events into items, coalesces runs of tool calls, then nests each
+    /// subagent spawn's own activity (drawn from `byParent`) as its `children`, recursing for
+    /// subagents-within-subagents up to `maxSubagentDepth`.
+    private static func project(
+        _ events: [AgentEvent], byParent: [String: [AgentEvent]], depth: Int,
+        showRaw: Bool, showLockEvents: Bool
+    ) -> [TranscriptItem] {
+        let items = coalesceToolRuns(flatItems(events, showRaw: showRaw, showLockEvents: showLockEvents))
+        guard depth < maxSubagentDepth else { return items }
+        return items.map {
+            attachSubagentChildren($0, byParent: byParent, depth: depth,
+                                   showRaw: showRaw, showLockEvents: showLockEvents)
+        }
+    }
+
+    /// For a subagent spawn (`Task`/`Agent`) — lone or inside a fan-out block — projects the
+    /// events it owns into its `children`. Leaves every ordinary tool untouched.
+    private static func attachSubagentChildren(
+        _ item: TranscriptItem, byParent: [String: [AgentEvent]], depth: Int,
+        showRaw: Bool, showLockEvents: Bool
+    ) -> TranscriptItem {
+        func childrenFor(_ group: ToolGroup) -> ToolGroup {
+            guard group.isOrchestration else { return group }
+            var g = group
+            g.children = project(byParent[group.toolCallID] ?? [], byParent: byParent, depth: depth + 1,
+                                 showRaw: showRaw, showLockEvents: showLockEvents)
+            return g
+        }
+        switch item.kind {
+        case .tool(let group):
+            guard group.isOrchestration else { return item }
+            return TranscriptItem(id: item.id, seq: item.seq, kind: .tool(childrenFor(group)))
+        case .toolBlock(let groups):
+            return TranscriptItem(id: item.id, seq: item.seq, kind: .toolBlock(groups.map(childrenFor)))
+        default:
+            return item
+        }
+    }
+
+    // MARK: - Tool-run coalescing
+
+    /// Collapses maximal runs of adjacent `.tool` items (length ≥2) into one `.toolBlock`.
+    ///
+    /// Items that draw nothing (empty `.thinking` blocks — see `rendersNothing`) never break a
+    /// run: an invisible row landing between two tool calls must not split them into two cards
+    /// with a gap. Such items are held aside and re-emitted right after the block, so they still
+    /// render in place while the calls stay one contiguous block. Mirrors the desktop projection.
+    static func coalesceToolRuns(_ flat: [TranscriptItem]) -> [TranscriptItem] {
+        var out: [TranscriptItem] = []
+        var run: [TranscriptItem] = []          // consecutive `.tool` items
+        var held: [TranscriptItem] = []         // non-rendering rows seen mid-run, held so they don't split it
+
+        func flush() {
+            if run.count == 1 {
+                out.append(run[0])
+            } else if run.count >= 2 {
+                let groups = run.compactMap { item -> ToolGroup? in
+                    if case .tool(let g) = item.kind { return g } else { return nil }
+                }
+                out.append(TranscriptItem(id: "toolblock-\(groups[0].toolCallID)",
+                                          seq: run[0].seq, kind: .toolBlock(groups)))
+            }
+            run.removeAll(keepingCapacity: true)
+            out.append(contentsOf: held)
+            held.removeAll(keepingCapacity: true)
+        }
+
+        for item in flat {
+            if case .tool = item.kind {
+                run.append(item)
+            } else if item.rendersNothing, !run.isEmpty {
+                held.append(item)
+            } else {
+                flush()
+                out.append(item)
+            }
+        }
+        flush()
+        return out
+    }
+
+    // MARK: - Flat projection (one scope)
+
+    /// Fold one scope's raw events into interleaved, display-ready rows: streaming assistant /
+    /// thinking deltas accumulate into one growing row, and a tool call shows the moment it starts
+    /// (`toolCallStarted`), with its full input/result/file-changes filled in as they arrive.
+    private static func flatItems(
+        _ events: [AgentEvent], showRaw: Bool, showLockEvents: Bool
+    ) -> [TranscriptItem] {
         var items: [TranscriptItem] = []
         var messageIndex: [String: Int] = [:]   // messageID → items index (text coalescing)
         var thinkingIndex: [String: Int] = [:]
@@ -145,11 +325,11 @@ enum TranscriptProjection {
             group.name = call.name
             if !call.input.isEmptyValue { group.input = call.input }
             group.finished = group.finished || finished
-            items[i].kind = wrap(group)
+            items[i].kind = .tool(group)
         } else {
             index[call.toolCallID] = items.count
             let group = ToolGroup(toolCallID: call.toolCallID, name: call.name, input: call.input, finished: finished)
-            items.append(.init(id: "tool-\(call.toolCallID)", seq: seq, kind: wrap(group)))
+            items.append(.init(id: "tool-\(call.toolCallID)", seq: seq, kind: .tool(group)))
         }
     }
 
@@ -160,7 +340,7 @@ enum TranscriptProjection {
         group.result = result.content
         group.isError = result.isError
         group.finished = true
-        items[i].kind = wrap(group)
+        items[i].kind = .tool(group)
     }
 
     private static func attachFileChange(
@@ -168,22 +348,16 @@ enum TranscriptProjection {
     ) {
         if let id = change.toolCallID, let i = index[id], var group = currentGroup(items[i]) {
             group.fileChanges.append(.init(path: change.path, change: change.kind))
-            items[i].kind = wrap(group)
+            items[i].kind = .tool(group)
         }
         // Untagged file changes are folded into the diff stat, not the transcript.
     }
 
-    /// Extract a tool group from either the plain or orchestration kind.
+    /// Extract a tool group from a `.tool` item (the only kind `flatItems` produces for a call;
+    /// blocks/children are formed later, after coalescing).
     private static func currentGroup(_ item: TranscriptItem) -> ToolGroup? {
-        switch item.kind {
+        if case .tool(let g) = item.kind { return g }
-        case .tool(let g), .orchestration(let g): return g
+        return nil
-        default: return nil
-        }
-    }
-
-    /// Wrap a group in the right kind — orchestration spawns get the gold card.
-    private static func wrap(_ group: ToolGroup) -> TranscriptItem.Kind {
-        group.isOrchestration ? .orchestration(group) : .tool(group)
     }
 }