From b80baad8e5eaaec90f02bb5eaf795bd25d3c793f Mon Sep 17 00:00:00 2001
From: Shivam Sharma <91240327+shivamhwp@users.noreply.github.com>
Date: Thu, 5 Nov 2026 08:27:20 +0530
Subject: [PATCH] fix(server): a stopped run no longer shrinks thread history
 to one row

#26435 dropped the half-budget floor for the visible window whenever any
retained dependency card exists, and every stored run_interrupt_request
counts as one. Threads with more than ~512 KiB of control state then
loaded a single history row. The floor now stays, minus the dependency
reserve, so large pending question cards still fit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../threadHistoryPaging.test.ts               | 69 ++++++++++---------
 .../orchestration-v2/threadHistoryPaging.ts   |  4 +-
 2 files changed, 40 insertions(+), 33 deletions(-)

diff --git a/apps/server/src/orchestration-v2/threadHistoryPaging.test.ts b/apps/server/src/orchestration-v2/threadHistoryPaging.test.ts
index eba4ceec7f6c8..111cf0541358a 100644
--- a/apps/server/src/orchestration-v2/threadHistoryPaging.test.ts
+++ b/apps/server/src/orchestration-v2/threadHistoryPaging.test.ts
@@ -904,39 +904,46 @@ describe("threadHistoryPaging", () => {
     expect(bounded.projection.visibleTurnItems).toEqual(actionable.visibleTurnItems);
   });
 
-  it("keeps agent-only turns visible when checkpoint file lists fill the byte budget", () => {
-    const items = Array.from({ length: 3 }, (_, turn) => {
-      const first = makeRow(turn * 5);
-      const prompt = {
-        ...first,
-        item: {
-          ...first.item,
-          type: "user_message" as const,
-          createdBy: "agent" as const,
-          creationSource: "provider" as const,
-          inputIntent: "turn_start" as const,
-          messageId: MessageId.make(`agent-prompt-${turn}`),
-          text: `Step ${turn}`,
-          attachments: [],
-        },
-      } as OrchestrationV2ProjectedTurnItem;
-      return [prompt, ...Array.from({ length: 4 }, (_, index) => makeRow(turn * 5 + index + 1))];
-    }).flat();
-    const files = Array.from(
-      { length: 15_000 },
-      (_, index) =>
-        `work/ws-${index % 40}/.jj/repo/store/extra/${index.toString(16).padStart(40, "0")}`,
-    );
-    const projection = {
-      ...makeProjection(items),
-      checkpoints: [{ id: "checkpoint-1", files }],
-    } as unknown as ReturnType<typeof makeProjection>;
+  it.each([false, true])(
+    "keeps agent-only turns visible when checkpoint file lists fill the byte budget (stored interrupt request: %s)",
+    (withInterruptRequest) => {
+      const items = Array.from({ length: 3 }, (_, turn) => {
+        const first = makeRow(turn * 5);
+        const prompt = {
+          ...first,
+          item: {
+            ...first.item,
+            type: "user_message" as const,
+            createdBy: "agent" as const,
+            creationSource: "provider" as const,
+            inputIntent: "turn_start" as const,
+            messageId: MessageId.make(`agent-prompt-${turn}`),
+            text: `Step ${turn}`,
+            attachments: [],
+          },
+        } as OrchestrationV2ProjectedTurnItem;
+        return [prompt, ...Array.from({ length: 4 }, (_, index) => makeRow(turn * 5 + index + 1))];
+      }).flat();
+      const files = Array.from(
+        { length: 15_000 },
+        (_, index) =>
+          `work/ws-${index % 40}/.jj/repo/store/extra/${index.toString(16).padStart(40, "0")}`,
+      );
+      const base = makeProjection(items);
+      const projection = {
+        ...base,
+        turnItems: withInterruptRequest
+          ? [interruptItem("old-interrupt-req", "run_interrupt_request", 0), ...base.turnItems]
+          : base.turnItems,
+        checkpoints: [{ id: "checkpoint-1", files }],
+      } as unknown as ReturnType<typeof makeProjection>;
 
-    const bounded = buildBoundedThreadProjection({ projection, snapshotSequence: 1 });
+      const bounded = buildBoundedThreadProjection({ projection, snapshotSequence: 1 });
 
-    expect(bounded.projection.visibleTurnItems).toHaveLength(items.length);
-    expect(bounded.hasMoreHistory).toBe(false);
-  });
+      expect(bounded.projection.visibleTurnItems).toHaveLength(items.length);
+      expect(bounded.hasMoreHistory).toBe(false);
+    },
+  );
 
   it("keeps paged historical plan detail in the turn item and only status in its artifact", () => {
     const detail = "Implement the historical plan exactly.\n".repeat(1_000);
diff --git a/apps/server/src/orchestration-v2/threadHistoryPaging.ts b/apps/server/src/orchestration-v2/threadHistoryPaging.ts
index d226d21e3248c..d96ef3c26b2cb 100644
--- a/apps/server/src/orchestration-v2/threadHistoryPaging.ts
+++ b/apps/server/src/orchestration-v2/threadHistoryPaging.ts
@@ -673,9 +673,9 @@ export function buildBoundedThreadProjection(input: {
     turnItems: [],
     visibleTurnItems: [],
   });
-  // Keep the control-only window minimum, but required dependency cards claim their reserve first.
+  // Control state cannot be paged, so the window keeps half the budget; dependency cards take their reserve from that half.
   const windowBudget = Math.max(
-    dependencyReserve === 0 ? policy.maxEncodedBytes / 2 : 0,
+    Math.max(policy.maxEncodedBytes / 2 - dependencyReserve, 0),
     policy.maxEncodedBytes - dependencyReserve - controlBytes - 1_024,
   );
   const windowPolicy: ThreadHistoryPagePolicy = { ...policy, maxEncodedBytes: windowBudget };