fix(console): preserve exact adopted history boundaries

web/workspace/src/lib/generated/protocol.ts

@@ -151,7 +151,12 @@ timestamp: number, provenance: SessionEntryProvenance, derived_from?: Array<stri
 
 export type SessionConversationTurn = { turn_id: string, entries: Array<SessionSnapshotEntry>, };
 
-export type SessionHistoryLineageBoundary = { lineage_id: string, adopted_through_turn_id?: string | null, };
+export type SessionHistoryLineageBoundary = { lineage_id: string,
+/**
+ * Canonical public form of the final user-visible turn at the exact
+ * provider boundary. Entries after that boundary are excluded.
+ */
+adopted_through_turn?: SessionConversationTurn | null, };
 
 export type SessionHistoryPage = { session_id: string,
 /**

web/workspace/src/lib/workspace/console/history.test.ts

@@ -58,7 +58,7 @@ function page(
   compactAncestorLineageIds: string[] = [],
   parentLineage?: {
     lineage_id: string;
-    adopted_through_turn_id?: string | null;
+    adopted_through_turn?: SessionConversationTurn | null;
   },
 ): SessionHistoryPage {
   return {
@@ -256,6 +256,10 @@ Deno.test("fork lineage boundary preserves an adopted prefix without page overla
     status: "loading",
     requestedCursor: "__initial__",
   };
+  state.turns[24]!.entries.push(
+    message("a-unadopted-25", "assistant", "stale sibling response"),
+  );
+  const adoptedBoundary = turn(25);
   state = applyConsoleHistoryPage(
     state,
     page(
@@ -265,7 +269,7 @@ Deno.test("fork lineage boundary preserves an adopted prefix without page overla
       [],
       {
         lineage_id: "lineage-a",
-        adopted_through_turn_id: "u-25",
+        adopted_through_turn: adoptedBoundary,
       },
     ),
     null,
@@ -279,6 +283,10 @@ Deno.test("fork lineage boundary preserves an adopted prefix without page overla
       ].join(","),
     "fork refresh must retain only the authoritative adopted prefix",
   );
+  assert(
+    historyEntries(state).every((entry) => entry.entry_id !== "a-unadopted-25"),
+    "the canonical provider boundary must trim a sibling entry in the same visible turn",
+  );
   assert(
     state.cursor === "cursor-101" && state.hasMore,
     "fork refresh must replace the old paging boundary",

web/workspace/src/lib/workspace/console/history.ts

@@ -102,7 +102,7 @@ export function applyConsoleHistoryPage(
       ? reconcileParentLineage(
         state.turns,
         incoming,
-        page.parent_lineage?.adopted_through_turn_id ?? null,
+        page.parent_lineage?.adopted_through_turn ?? null,
       )
       : refreshingCompactDescendant
       ? mergeRefreshedTurns(state.turns, incoming)
@@ -230,14 +230,21 @@ function previewAssistant(value: string): string[] {
 function reconcileParentLineage(
   retained: readonly SessionConversationTurn[],
   refreshed: readonly SessionConversationTurn[],
-  adoptedThroughTurnId: string | null,
+  adoptedThroughTurn: SessionConversationTurn | null,
 ): SessionConversationTurn[] {
-  if (adoptedThroughTurnId === null) return dedupeTurns(refreshed);
+  if (adoptedThroughTurn === null) return dedupeTurns(refreshed);
   const boundary = retained.findIndex((turn) =>
-    turn.turn_id === adoptedThroughTurnId
+    turn.turn_id === adoptedThroughTurn.turn_id
   );
   if (boundary < 0) return dedupeTurns(refreshed);
-  return dedupeTurns([...retained.slice(0, boundary + 1), ...refreshed]);
+  const refreshedIncludesBoundary = refreshed.some((turn) =>
+    turn.turn_id === adoptedThroughTurn.turn_id
+  );
+  return dedupeTurns([
+    ...retained.slice(0, boundary),
+    ...(refreshedIncludesBoundary ? [] : [adoptedThroughTurn]),
+    ...refreshed,
+  ]);
 }
 
 function reconcileChangedLineage(

web/workspace/src/lib/workspace/console/model.test.ts

@@ -3127,6 +3127,21 @@ Deno.test("committed history places omitted retained rows between snapshot ancho
   );
 });
 
+Deno.test("committed history places current context before an interior first anchor", () => {
+  const makeLine = (prefix: string, turn: number) => {
+    const line = consoleLine(`${prefix}-${turn}`, "user");
+    line.entryId = `user-${turn}`;
+    return line;
+  };
+  const history = [6, 7, 8, 9, 10].map((turn) => makeLine("history", turn));
+  const current = [1, 8, 10].map((turn) => makeLine("current", turn));
+
+  assertEquals(
+    mergeCommittedHistoryLines(history, current).map((line) => line.entryId),
+    [1, 6, 7, 8, 9, 10].map((turn) => `user-${turn}`),
+  );
+});
+
 Deno.test("committed history places a retained suffix before newer current-only rows", () => {
   const makeLine = (prefix: string, turn: number) => {
     const line = consoleLine(`${prefix}-${turn}`, "user");

web/workspace/src/lib/workspace/console/model.ts

@@ -334,9 +334,16 @@ export function mergeCommittedHistoryLines(
       }
     }
   };
-  for (const anchor of anchors) {
-    appendHistoryInterval(anchor.history);
-    merged.push(...current.slice(currentCursor, anchor.current));
+  for (const [index, anchor] of anchors.entries()) {
+    if (index === 0) {
+      // Current rows before the first shared entry can be older retained
+      // context that the newest history page starts after.
+      merged.push(...current.slice(currentCursor, anchor.current));
+      appendHistoryInterval(anchor.history);
+    } else {
+      appendHistoryInterval(anchor.history);
+      merged.push(...current.slice(currentCursor, anchor.current));
+    }
     merged.push(current[anchor.current]!);
     historyCursor = anchor.history + 1;
     currentCursor = anchor.current + 1;

web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/console-display.browser.spec.ts

@@ -11,6 +11,7 @@ import {
 import { afterEach, beforeEach, expect, test, vi } from "vitest";
 import type {
   Event as ProtocolEvent,
+  SessionConversationTurn,
   SessionSnapshot,
 } from "$lib/generated/protocol";
 import type { Worker } from "$lib/workspace/sidebar/types";
@@ -127,7 +128,7 @@ function historyPage(
   lineageId = "lineage-a",
   parentLineage?: {
     lineage_id: string;
-    adopted_through_turn_id?: string | null;
+    adopted_through_turn?: SessionConversationTurn | null;
   },
 ) {
   return {
@@ -506,7 +507,8 @@ test("fork refresh reconciles an in-flight older page to the adopted prefix", as
         "lineage-fork",
         {
           lineage_id: "lineage-a",
-          adopted_through_turn_id: "user-48",
+          adopted_through_turn: historyPage([48], null).page
+            .turns[0] as SessionConversationTurn,
         },
       )));
     }),