Fix compact subagent copied prefixes

Sources/CodexBarCore/Generated/CodexParserHash.generated.swift

@@ -1,5 +1,5 @@
 // Generated by Scripts/regenerate-codex-parser-hash.sh. Do not edit by hand.
 
 enum CodexParserHash {
-    static let value = "338e4ab0fe153f95"
+    static let value = "48ac20dad61e9a7f"
 }

Sources/CodexBarCore/Vendored/CostUsage/CodexSubagentRolloutShape.swift

@@ -7,18 +7,25 @@ extension CostUsageScanner {
     }
 
     /// Subagent source is lineage evidence, not counter semantics. The first session metadata
-    /// owns leaf identity; only embedded metadata proves that this rollout copied an ancestor
-    /// prefix. Do not restore a blanket "all subagents are independent/inherited" rule.
+    /// owns leaf identity. Embedded ancestor metadata proves a copied prefix by itself; compact
+    /// rollouts need both the first-turn boundary and an exact parent snapshot match in the scanner.
+    /// Do not restore a blanket "all subagents are independent/inherited" rule.
     struct CodexSubagentRolloutShape {
         let counterSemantics: CodexSubagentCounterSemantics
         let ownedSuffix: CodexSubagentOwnedSuffix?
+        let ownedSuffixCandidate: CodexSubagentOwnedSuffixCandidate?
         let inferredParentSessionID: String?
 
         struct CodexSubagentOwnedSuffix {
             let startLineIndex: Int
             let rawTotalsBaseline: CostUsageCodexTotals
         }
 
+        struct CodexSubagentOwnedSuffixCandidate {
+            let ownedSuffix: CodexSubagentOwnedSuffix
+            let parentTotalsAtBoundary: CostUsageCodexTotals
+        }
+
         struct Observation {
             let lineIndex: Int
             let kind: Kind
@@ -50,12 +57,14 @@ extension CostUsageScanner {
             return Self(
                 counterSemantics: hasEmbeddedAncestor ? .copiedPrefix : .independent,
                 ownedSuffix: nil,
+                ownedSuffixCandidate: nil,
                 inferredParentSessionID: inferredParentSessionID)
         }
 
         static func classify(
             leafSessionID: String?,
-            observations: [Observation]) -> Self
+            observations: [Observation],
+            hasExplicitParent: Bool = false) -> Self
         {
             let metadataIDs = observations.reduce(into: [String?]()) { result, observation in
                 guard case let .sessionMetadata(id) = observation.kind else { return }
@@ -64,14 +73,19 @@ extension CostUsageScanner {
             let metadataShape = Self.classify(
                 leafSessionID: leafSessionID,
                 observedSessionIDs: metadataIDs)
-            guard metadataShape.counterSemantics == .copiedPrefix else { return metadataShape }
+            let canProposeParentConfirmedSuffix = metadataShape.counterSemantics == .independent
+                && hasExplicitParent
+            guard metadataShape.counterSemantics == .copiedPrefix || canProposeParentConfirmedSuffix
+            else { return metadataShape }
 
             let normalizedLeafID = Self.normalizedSessionID(leafSessionID)
             var lastRawTotals: CostUsageCodexTotals?
             var pendingTurnContext: (lineIndex: Int, baseline: CostUsageCodexTotals)?
             var ownedSuffix: CodexSubagentOwnedSuffix?
+            var parentTotalsAtBoundary: CostUsageCodexTotals?
             var inspectedOwnedSuffixFirstTotal = false
             var observedAuthoritativeMetadata = false
+            var observedTurnContext = false
 
             for observation in observations {
                 switch observation.kind {
@@ -88,22 +102,32 @@ extension CostUsageScanner {
                     if isEmbeddedAncestor {
                         // A later ancestor meta proves that any earlier candidate boundary was replay.
                         ownedSuffix = nil
+                        parentTotalsAtBoundary = nil
                         inspectedOwnedSuffixFirstTotal = false
                     }
                     pendingTurnContext = nil
 
                 case .turnContext:
-                    pendingTurnContext = lastRawTotals.map { (observation.lineIndex, $0) }
+                    let isFirstTurnContext = !observedTurnContext
+                    observedTurnContext = true
+                    let acceptsBoundary = metadataShape.counterSemantics == .copiedPrefix
+                        || (canProposeParentConfirmedSuffix && isFirstTurnContext)
+                    pendingTurnContext = acceptsBoundary
+                        ? lastRawTotals.map { (observation.lineIndex, $0) }
+                        : nil
 
                 case let .interAgentCommunication(triggerTurn):
                     if ownedSuffix == nil,
                        triggerTurn,
                        let pendingTurnContext,
-                       observation.lineIndex == pendingTurnContext.lineIndex + 1
+                       observation.lineIndex == pendingTurnContext.lineIndex + 1,
+                       metadataShape.counterSemantics == .copiedPrefix
+                       || Self.totalsContainUsage(pendingTurnContext.baseline)
                     {
                         ownedSuffix = Self.CodexSubagentOwnedSuffix(
                             startLineIndex: pendingTurnContext.lineIndex,
                             rawTotalsBaseline: pendingTurnContext.baseline)
+                        parentTotalsAtBoundary = pendingTurnContext.baseline
                         inspectedOwnedSuffixFirstTotal = false
                     }
                     pendingTurnContext = nil
@@ -132,9 +156,25 @@ extension CostUsageScanner {
                 }
             }
 
+            if metadataShape.counterSemantics == .copiedPrefix {
+                return Self(
+                    counterSemantics: .copiedPrefix,
+                    ownedSuffix: ownedSuffix,
+                    ownedSuffixCandidate: nil,
+                    inferredParentSessionID: metadataShape.inferredParentSessionID)
+            }
+
+            let candidate: CodexSubagentOwnedSuffixCandidate? = if let ownedSuffix, let parentTotalsAtBoundary {
+                Self.CodexSubagentOwnedSuffixCandidate(
+                    ownedSuffix: ownedSuffix,
+                    parentTotalsAtBoundary: parentTotalsAtBoundary)
+            } else {
+                nil
+            }
             return Self(
-                counterSemantics: .copiedPrefix,
-                ownedSuffix: ownedSuffix,
+                counterSemantics: .independent,
+                ownedSuffix: nil,
+                ownedSuffixCandidate: candidate,
                 inferredParentSessionID: metadataShape.inferredParentSessionID)
         }
 
@@ -153,6 +193,10 @@ extension CostUsageScanner {
             lhs.input >= rhs.input && lhs.cached >= rhs.cached && lhs.output >= rhs.output
         }
 
+        private static func totalsContainUsage(_ totals: CostUsageCodexTotals) -> Bool {
+            totals.input > 0 || totals.cached > 0 || totals.output > 0
+        }
+
         private static func normalizedSessionID(_ value: String?) -> String? {
             guard let value else { return nil }
             let trimmed = value.trimmingCharacters(in: .whitespacesAndNewlines)

Sources/CodexBarCore/Vendored/CostUsage/CostUsageScanner.swift

@@ -2040,6 +2040,8 @@ enum CostUsageScanner {
         var forkTimestamp: String?
         var subagentCounterSemantics: CodexSubagentCounterSemantics?
         var usesLocalSubagentBoundary = false
+        var candidateBoundaryDependsOnParentTotals = false
+        var parentConfirmedLocalBoundary = false
         var suppressUnownedCopiedPrefix = false
         var inheritedTotals: CostUsageCodexTotals?
         var remainingInheritedTotals: CostUsageCodexTotals?
@@ -2603,15 +2605,34 @@ enum CostUsageScanner {
                 }
                 let shape = CodexSubagentRolloutShape.classify(
                     leafSessionID: sessionId,
-                    observations: observations)
+                    observations: observations,
+                    hasExplicitParent: forkedFromId != nil)
                 subagentCounterSemantics = shape.counterSemantics
                 if forkedFromId == nil {
                     forkedFromId = shape.inferredParentSessionID
                 }
-                suppressUnownedCopiedPrefix = shape.counterSemantics == .copiedPrefix
-                    && shape.ownedSuffix == nil
+                var ownedSuffix = shape.ownedSuffix
+                if let candidate = shape.ownedSuffixCandidate,
+                   let parentSessionID = forkedFromId
+                {
+                    candidateBoundaryDependsOnParentTotals = true
+                    if let inheritedTotalsResolver {
+                        switch try inheritedTotalsResolver(parentSessionID, forkTimestamp ?? "") {
+                        case let .resolved(parentTotals):
+                            if Self.codexTotalsEqual(parentTotals, candidate.parentTotalsAtBoundary) {
+                                subagentCounterSemantics = .copiedPrefix
+                                ownedSuffix = candidate.ownedSuffix
+                                parentConfirmedLocalBoundary = true
+                            }
+                        case .unresolved:
+                            break
+                        }
+                    }
+                }
+                suppressUnownedCopiedPrefix = subagentCounterSemantics == .copiedPrefix
+                    && ownedSuffix == nil
                     && forkedFromId == nil
-                if let ownedSuffix = shape.ownedSuffix {
+                if let ownedSuffix {
                     usesLocalSubagentBoundary = true
                     previousTotals = nil
                     // Keep totals-derived accounting after the boundary. Real flat-total rows
@@ -2632,7 +2653,8 @@ enum CostUsageScanner {
                     metadata: [
                         "sessionId": sessionId ?? "unknown",
                         "semantics": subagentCounterSemantics == .copiedPrefix ? "copiedPrefix" : "independent",
-                        "localBoundary": shape.ownedSuffix == nil ? "false" : "true",
+                        "localBoundary": ownedSuffix == nil ? "false" : "true",
+                        "parentConfirmedBoundary": parentConfirmedLocalBoundary ? "true" : "false",
                         "suppressedUnownedPrefix": suppressUnownedCopiedPrefix ? "true" : "false",
                         "sessionMetadataCount": String(observations.count(where: {
                             if case .sessionMetadata = $0.kind {
@@ -2644,7 +2666,7 @@ enum CostUsageScanner {
                     ])
                 try configureForkAccountingIfReady()
                 for buffered in pendingSubagentLines
-                    where shape.ownedSuffix.map({ buffered.lineIndex >= $0.startLineIndex }) ?? true
+                    where ownedSuffix.map({ buffered.lineIndex >= $0.startLineIndex }) ?? true
                 {
                     try processFastLine(buffered.line)
                 }
@@ -2675,8 +2697,8 @@ enum CostUsageScanner {
             sessionId: sessionId,
             forkedFromId: forkedFromId,
             dependsOnParentTotals: forkedFromId != nil
-                && subagentCounterSemantics != .independent
-                && !usesLocalSubagentBoundary,
+                && (candidateBoundaryDependsOnParentTotals
+                    || (subagentCounterSemantics != .independent && !usesLocalSubagentBoundary)),
             projectPath: projectPath,
             rows: rows)
     }