From 56fffe6162150a0f68fbcbbe2afb843d71482113 Mon Sep 17 00:00:00 2001
From: BarryYangi <barry@yct.ee>
Date: Sun, 17 May 2026 23:47:12 +0800
Subject: [PATCH] Fix Codex model attribution for large turn contexts

---
 .../Vendored/CostUsage/CostUsageScanner.swift |  2 +-
 .../CostUsageScannerPriorityTests.swift       | 43 +++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/Sources/CodexBarCore/Vendored/CostUsage/CostUsageScanner.swift b/Sources/CodexBarCore/Vendored/CostUsage/CostUsageScanner.swift
index a8b75f766..fca3d4290 100644
--- a/Sources/CodexBarCore/Vendored/CostUsage/CostUsageScanner.swift
+++ b/Sources/CodexBarCore/Vendored/CostUsage/CostUsageScanner.swift
@@ -769,7 +769,7 @@ enum CostUsageScanner {
         }
 
         let maxLineBytes = 256 * 1024
-        let prefixBytes = 32 * 1024
+        let prefixBytes = maxLineBytes
 
         if startOffset == 0,
            let metadata = Self.parseCodexSessionMetadata(fileURL: fileURL)
diff --git a/Tests/CodexBarTests/CostUsageScannerPriorityTests.swift b/Tests/CodexBarTests/CostUsageScannerPriorityTests.swift
index e52a3dd47..9dd24a418 100644
--- a/Tests/CodexBarTests/CostUsageScannerPriorityTests.swift
+++ b/Tests/CodexBarTests/CostUsageScannerPriorityTests.swift
@@ -120,6 +120,49 @@ struct CostUsageScannerPriorityTests {
         #expect(report.summary?.totalCostUSD == expected)
     }
 
+    @Test
+    func `codex daily report keeps model from large turn context`() throws {
+        let env = try CostUsageTestEnvironment()
+        defer { env.cleanup() }
+
+        let day = try env.makeLocalNoon(year: 2026, month: 5, day: 15)
+        let iso0 = env.isoString(for: day)
+        let iso1 = env.isoString(for: day.addingTimeInterval(1))
+        let largeInstructions = String(repeating: "x", count: 33 * 1024)
+        let entries: [[String: Any]] = [
+            [
+                "type": "turn_context",
+                "timestamp": iso0,
+                "payload": [
+                    "model": "gpt-5.5",
+                    "developer_instructions": largeInstructions,
+                ],
+            ],
+            ["type": "event_msg", "timestamp": iso1, "payload": ["type": "task_started", "turn_id": "subagent-turn"]],
+            self.tokenCount(timestamp: iso1, input: 100, cached: 20, output: 10),
+        ]
+        _ = try env.writeCodexSessionFile(
+            day: day,
+            filename: "subagent-large-turn-context.jsonl",
+            contents: env.jsonl(entries))
+
+        var options = CostUsageScanner.Options(
+            codexSessionsRoot: env.codexSessionsRoot,
+            cacheRoot: env.cacheRoot)
+        options.refreshMinIntervalSeconds = 0
+
+        let report = CostUsageScanner.loadDailyReport(
+            provider: .codex,
+            since: day,
+            until: day,
+            now: day,
+            options: options)
+
+        #expect(report.data.count == 1)
+        #expect(report.data[0].modelsUsed == ["gpt-5.5"])
+        #expect(report.data[0].modelBreakdowns?.map(\.modelName) == ["gpt-5.5"])
+    }
+
     @Test
     func `codex pricing skips priority surcharge for long context rows`() throws {
         let env = try CostUsageTestEnvironment()