@@ -2252,7 +2252,10 @@ export namespace Telemetry {
   // whether any workspace context was in play. Keyed by session so a serve process with several
   // sessions keeps them apart; cleared when the session ends.
   export type WorkspaceUse = { skills: number; memory: number; integrations: number }
+  /** Keyed by session and turn, so a cancelled turn unwinding late and its replacement never share
+   * counts; a site that carries no turn counts toward the session's current one. */
   const workspaceUse = new Map<string, WorkspaceUse>()
+  const useKey = (sessionId: string, turn?: number) => `${sessionId}#${turn ?? sessionTurns.get(sessionId) ?? 0}`
   /** `add` accumulates; `max` records the largest value seen in the turn (memory is injected on every
    * step of a turn, so a sum would multiply the blocks by the step count). */
   export function noteWorkspaceUse(
@@ -2266,15 +2269,17 @@ export namespace Telemetry {
   ) {
     if (!sessionId || n <= 0) return
     if (turn !== undefined && sessionTurns.get(sessionId) !== turn) return
-    const use = workspaceUse.get(sessionId) ?? { skills: 0, memory: 0, integrations: 0 }
+    const key = useKey(sessionId, turn)
+    const use = workspaceUse.get(key) ?? { skills: 0, memory: 0, integrations: 0 }
     use[kind] = mode === "max" ? Math.max(use[kind], n) : use[kind] + n
-    workspaceUse.set(sessionId, use)
+    workspaceUse.set(key, use)
   }
-  export function workspaceUseOf(sessionId: string): WorkspaceUse {
-    return { skills: 0, memory: 0, integrations: 0, ...workspaceUse.get(sessionId) }
+  /** The counts of a turn (the session's current one when no turn is given). */
+  export function workspaceUseOf(sessionId: string, turn?: number): WorkspaceUse {
+    return { skills: 0, memory: 0, integrations: 0, ...workspaceUse.get(useKey(sessionId, turn)) }
   }
-  export function clearWorkspaceUse(sessionId: string) {
-    workspaceUse.delete(sessionId)
+  export function clearWorkspaceUse(sessionId: string, turn?: number) {
+    workspaceUse.delete(useKey(sessionId, turn))
   }
   /** The workspace a session's turn bound, or undefined when unbound or unknown. */
   export function workspaceOf(sessionId: string): number | undefined {
@@ -2284,8 +2289,12 @@ export namespace Telemetry {
    * its workspace entry goes. With `turn` (from `setContext`), a turn that is no longer the session's
    * current one ends nothing: the replacement's entries are the replacement's. */
   export function endSession(sessionId: string, turn?: number) {
-    if (turn !== undefined && sessionTurns.get(sessionId) !== turn) return
-    workspaceUse.delete(sessionId)
+    if (turn !== undefined && sessionTurns.get(sessionId) !== turn) {
+      // A turn that was replaced ends only its own counts; the replacement's entries stay.
+      workspaceUse.delete(useKey(sessionId, turn))
+      return
+    }
+    workspaceUse.delete(useKey(sessionId, turn))
     sessionWorkspaces.delete(sessionId)
     sessionTurns.delete(sessionId)
   }
 
@@ -113,8 +113,8 @@ import { readLocalBinding } from "@/altimate/workspace/state"
 /** The session's workspace use, as session_end fields. Read only: the row is tracked first, then the
  * turn ends its telemetry entries (`Telemetry.endSession`), so the row itself still carries the
  * workspace. */
-function workspaceUseFields(sessionID: string) {
-  const use = Telemetry.workspaceUseOf(sessionID)
+function workspaceUseFields(sessionID: string, turn: number) {
+  const use = Telemetry.workspaceUseOf(sessionID, turn)
   return {
     workspace_skills_used: use.skills,
     workspace_memory_blocks: use.memory,
@@ -827,7 +827,7 @@ export namespace SessionPrompt {
         tool_call_count: toolCallCount,
         duration_ms: Date.now() - sessionStartTime,
         // altimate_change start — what of the bound workspace this session used
-        ...workspaceUseFields(sessionID),
+        ...workspaceUseFields(sessionID, telemetryTurn),
         // altimate_change end
       })
       Telemetry.endSession(sessionID, telemetryTurn) // altimate_change — after the row, this turn only
@@ -2143,7 +2143,7 @@ export namespace SessionPrompt {
       duration_ms: Date.now() - sessionStartTime,
       last_tool_category: lastToolCategory || "none",
       // altimate_change — whether workspace skills, memory or integrations were in play
-      workspace_context_used: Object.values(Telemetry.workspaceUseOf(sessionID)).some((n) => n > 0),
+      workspace_context_used: Object.values(Telemetry.workspaceUseOf(sessionID, telemetryTurn)).some((n) => n > 0),
     })
     // Tool chain effectiveness — aggregated tool sequence + outcome
     if (toolChain.length > 0) {
@@ -2236,7 +2236,7 @@ export namespace SessionPrompt {
         tool_call_count: toolCallCount,
         duration_ms: Date.now() - sessionStartTime,
         // altimate_change start — what of the bound workspace this session used
-        ...workspaceUseFields(sessionID),
+        ...workspaceUseFields(sessionID, telemetryTurn),
         // altimate_change end
       })
       Telemetry.endSession(sessionID, telemetryTurn) // altimate_change — after the row, this turn only
 
@@ -88,8 +88,12 @@ describe("workspace id on the telemetry context", () => {
     const second = Telemetry.setContext({ sessionId: "s7", projectId: "p1", workspaceId: 42 })
     expect(second).toBeGreaterThan(first)
     Telemetry.noteWorkspaceUse("s7", "memory", 2)
+    // Counts are per turn: the cancelled turn's rows read its own, the replacement's its own.
+    expect(Telemetry.workspaceUseOf("s7", first)).toEqual({ skills: 1, memory: 0, integrations: 0 })
+    expect(Telemetry.workspaceUseOf("s7", second)).toEqual({ skills: 0, memory: 2, integrations: 0 })
     Telemetry.endSession("s7", first) // the old generation, after the replacement started
     expect(Telemetry.workspaceOf("s7")).toBe(42)
+    expect(Telemetry.workspaceUseOf("s7", first)).toEqual({ skills: 0, memory: 0, integrations: 0 })
     expect(Telemetry.workspaceUseOf("s7").memory).toBe(2)
     // A use landing with a stale turn does not count toward the replacement.
     Telemetry.noteWorkspaceUse("s7", "integrations", 1, "add", first)