diff --git a/apps/portal/src/hooks/useHarExtraction.test.tsx b/apps/portal/src/hooks/useHarExtraction.test.tsx
new file mode 100644
index 000000000..d9d410995
--- /dev/null
+++ b/apps/portal/src/hooks/useHarExtraction.test.tsx
@@ -0,0 +1,64 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+// @vitest-environment happy-dom
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { cleanup, renderHook, waitFor } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import type { ReactNode } from "react";
+import type { ConversationTurn } from "@/types";
+import { api } from "@/lib/api";
+import { apiClient } from "@/lib/api-client";
+import { useAllTurnsToolCalls } from "./useHarExtraction";
+
+vi.mock("@/lib/api", () => ({
+  api: {
+    toolCallsUrl: vi.fn(() => "/api/v1/requests/request-1/tool-calls?iteration=1"),
+    runToolCallsUrl: vi.fn(() => "/api/v1/requests/request-1/runs/attempt-1/tool-calls?iteration=1"),
+  },
+}));
+vi.mock("@/lib/api-client", () => ({ apiClient: vi.fn() }));
+
+function wrapper({ children }: { children: ReactNode }) {
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  return <QueryClientProvider client={client}>{children}</QueryClientProvider>;
+}
+
+afterEach(() => {
+  cleanup();
+  vi.clearAllMocks();
+});
+
+describe("useAllTurnsToolCalls", () => {
+  it("reads only the JSONL artifact for a historical attempt", async () => {
+    const turns = [{
+      iteration: 1,
+      toolCallsUrl: "https://blob/tool-calls.jsonl",
+      harUrl: "https://blob/run.har",
+      toolCalls: [{ id: "old", name: "legacy", arguments: {} }],
+    }] as ConversationTurn[];
+    vi.mocked(apiClient).mockResolvedValue({
+      ok: true,
+      text: async () => '{"id":"new","name":"read_file","arguments":{}}\n',
+    } as Response);
+
+    const { result } = renderHook(() => useAllTurnsToolCalls("request-1", turns, "attempt-1"), { wrapper });
+
+    await waitFor(() => expect(result.current.isLoading).toBe(false));
+    expect(result.current.allToolCalls).toEqual([{
+      id: "new", name: "read_file", arguments: {}, timestamp: "", _iteration: 1,
+    }]);
+    expect(api.runToolCallsUrl).toHaveBeenCalledWith("request-1", "attempt-1", 1);
+    expect(apiClient).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not fetch a HAR for turns without a tool-calls artifact", () => {
+    const turns = [{ iteration: 1, harUrl: "https://blob/run.har" }] as ConversationTurn[];
+
+    const { result } = renderHook(() => useAllTurnsToolCalls("request-1", turns), { wrapper });
+
+    expect(result.current.allToolCalls).toEqual([]);
+    expect(result.current.isLoading).toBe(false);
+    expect(apiClient).not.toHaveBeenCalled();
+  });
+});
diff --git a/apps/portal/src/hooks/useHarExtraction.ts b/apps/portal/src/hooks/useHarExtraction.ts
index 6830411e3..0b40af56f 100644
--- a/apps/portal/src/hooks/useHarExtraction.ts
+++ b/apps/portal/src/hooks/useHarExtraction.ts
@@ -7,7 +7,6 @@ import { api } from "@/lib/api";
 import { apiClient } from "@/lib/api-client";
 import type { ConversationTurn } from "@/types";
 import {
-  extractChronologicalSegments,
   extractFromHar,
   type ConversationSegment,
   type HarExtractedData,
@@ -54,7 +53,7 @@ export function useHarExtraction(runId: string, iteration?: number, hasHar?: boo
 }
 
 // ---------------------------------------------------------------------------
-// React hook: fetch HARs for ALL turns and aggregate tool calls
+// React hook: fetch server-extracted tool calls for all turns
 // ---------------------------------------------------------------------------
 export interface AggregatedToolCall extends ToolCall {
   _iteration?: number;
@@ -63,34 +62,14 @@ export interface AggregatedToolCall extends ToolCall {
 export function useAllTurnsToolCalls(
   runId: string,
   turns?: ConversationTurn[],
-  topLevelHarUrl?: string,
   attemptRunId?: string,
 ): { allToolCalls: AggregatedToolCall[]; isLoading: boolean } {
-  // Turns that already have pre-computed `toolCalls` (legacy inline shape)
-  // don't need any blob fetch.
-  const preComputed = useMemo(() => {
-    const out: AggregatedToolCall[] = [];
-    if (turns) {
-      for (const t of turns) {
-        if (t.toolCalls && t.toolCalls.length > 0) {
-          for (const tc of t.toolCalls) {
-            out.push({ ...tc, timestamp: tc.timestamp ?? "", _iteration: t.iteration });
-          }
-        }
-      }
-    }
-    return out;
-  }, [turns]);
-
-  // New shape: per-iteration tool-calls.jsonl in blob storage. Fetched via
-  // the API proxy (`/api/v1/requests/:id/tool-calls?iteration=N`) and parsed
-  // line-by-line. Preferred over re-extracting from the HAR.
+  // Per-iteration tool-calls.jsonl is the source for the Tool Calls tab.
   const jsonlQueries = useMemo(() => {
     const q: { iteration: number }[] = [];
     if (turns) {
       for (const t of turns) {
-        const hasInline = t.toolCalls && t.toolCalls.length > 0;
-        if (!hasInline && t.toolCallsUrl) {
+        if (t.toolCallsUrl) {
           q.push({ iteration: t.iteration });
         }
       }
@@ -115,48 +94,8 @@ export function useAllTurnsToolCalls(
     })),
   });
 
-  // Legacy fallback: turns that have `harUrl` but neither inline `toolCalls`
-  // nor a `toolCallsUrl` blob — re-extract from the HAR.
-  const queries = useMemo(() => {
-    const q: { iteration: number | undefined; enabled: boolean }[] = [];
-
-    // One-shot run: top-level HAR, no iteration
-    if (topLevelHarUrl && (!turns || turns.length === 0)) {
-      q.push({ iteration: undefined, enabled: true });
-    }
-
-    // Multi-turn: one query per turn with harUrl but WITHOUT pre-computed
-    // toolCalls and WITHOUT a tool-calls JSONL blob.
-    if (turns) {
-      for (const t of turns) {
-        const hasInline = t.toolCalls && t.toolCalls.length > 0;
-        const hasJsonl = !!t.toolCallsUrl;
-        if (t.harUrl && !hasInline && !hasJsonl) {
-          q.push({ iteration: t.iteration, enabled: true });
-        }
-      }
-    }
-
-    return q;
-  }, [turns, topLevelHarUrl]);
-
-  const results = useQueries({
-    queries: queries.map((q) => ({
-      queryKey: ["har", runId, q.iteration, attemptRunId],
-      queryFn: async () => {
-        const url = attemptRunId ? api.runHarUrl(runId, attemptRunId, q.iteration) : api.harUrl(runId, q.iteration);
-        const res = await apiClient(url);
-        if (!res.ok) throw new Error(`HTTP ${res.status}`);
-        return res.json() as Promise<HarFile>;
-      },
-      enabled: q.enabled,
-      staleTime: Infinity,
-    })),
-  });
-
   const allToolCalls = useMemo(() => {
-    const out: AggregatedToolCall[] = [...preComputed];
-    // JSONL blob fetches first
+    const out: AggregatedToolCall[] = [];
     for (let i = 0; i < jsonlResults.length; i++) {
       const tcs = jsonlResults[i].data;
       if (!tcs) continue;
@@ -165,23 +104,10 @@ export function useAllTurnsToolCalls(
         out.push({ ...tc, timestamp: tc.timestamp ?? "", _iteration: iteration });
       }
     }
-    // Legacy HAR re-extraction
-    for (let i = 0; i < results.length; i++) {
-      const har = results[i].data;
-      if (!har) continue;
-      const segments = extractChronologicalSegments(har);
-      const tcs = segments
-        .filter((s): s is ConversationSegment & { type: "tool_calls" } => s.type === "tool_calls")
-        .flatMap((s) => s.toolCalls);
-      const iteration = queries[i].iteration;
-      for (const tc of tcs) {
-        out.push({ ...tc, _iteration: iteration });
-      }
-    }
     return out;
-  }, [preComputed, jsonlResults, jsonlQueries, results, queries]);
+  }, [jsonlResults, jsonlQueries]);
 
-  const isLoading = results.some((r) => r.isLoading) || jsonlResults.some((r) => r.isLoading);
+  const isLoading = jsonlResults.some((r) => r.isLoading);
 
   return { allToolCalls, isLoading };
 }
diff --git a/apps/portal/src/pages/RunDetail.tsx b/apps/portal/src/pages/RunDetail.tsx
index 77ac6b0fa..144af623e 100644
--- a/apps/portal/src/pages/RunDetail.tsx
+++ b/apps/portal/src/pages/RunDetail.tsx
@@ -1688,7 +1688,7 @@ export function RunDetail() {
         {/* Tool Calls tab — HAR captures & tool calls summary */}
         {hasHarData && (
           <TabsContent value="tool-calls" className="mt-4 space-y-4">
-            <ToolCallsTab runId={run._id} turns={activeRun?.turns} harUrl={activeRun?.harUrl} attemptRunId={isViewingHistorical ? activeRun?._id : undefined} />
+            <ToolCallsTab runId={run._id} turns={activeRun?.turns} attemptRunId={isViewingHistorical ? activeRun?._id : undefined} />
           </TabsContent>
         )}
       </Tabs>
@@ -1811,7 +1811,7 @@ function VideoIterationTabs({ runId, turns, setupVideoUrls, attemptRunId }: { ru
 }
 
 // ---------------------------------------------------------------------------
-// Tool Calls tab — extracts tool calls from HAR client-side
+// Tool Calls tab — reads server-extracted per-iteration tool calls
 // ---------------------------------------------------------------------------
 
 import type { ConversationTurn } from "@/types";
@@ -1830,8 +1830,8 @@ function ExpandableCell({ children, className = "" }: { children: React.ReactNod
   );
 }
 
-function ToolCallsTab({ runId, turns, harUrl, attemptRunId }: { runId: string; turns?: ConversationTurn[]; harUrl?: string; attemptRunId?: string }) {
-  const { allToolCalls, isLoading } = useAllTurnsToolCalls(runId, turns, harUrl, attemptRunId);
+function ToolCallsTab({ runId, turns, attemptRunId }: { runId: string; turns?: ConversationTurn[]; attemptRunId?: string }) {
+  const { allToolCalls, isLoading } = useAllTurnsToolCalls(runId, turns, attemptRunId);
 
   // Group by tool name for summary
   const byName = new Map<string, number>();
diff --git a/docs/research/realtime-data-flow.md b/docs/research/realtime-data-flow.md
index abe77fd3d..1c0aece61 100644
--- a/docs/research/realtime-data-flow.md
+++ b/docs/research/realtime-data-flow.md
@@ -65,8 +65,10 @@ read lazily by clients (no SSE stream — fetched on demand by ID/iteration):
 
 Tool-call JSONL was introduced (#812) to keep unbounded per-iteration tool-call
 lists out of the `RequestDocument` (CosmosDB document size is capped at 2 MB).
-The turn carries only `toolCallsUrl` + `toolCallCount`; legacy turns with an
-inline `toolCalls[]` array remain readable for backwards compatibility.
+The turn carries `toolCallsUrl` + `toolCallCount`. The Portal Tool Calls tab
+reads only these server-extracted JSONL blobs; it no longer downloads HARs or
+uses legacy inline `toolCalls[]` for that tab. Other HAR-backed views still
+use `useHarData` for conversation and network details.
 
 ## React Query Polling