diff --git a/src/main/persistence.test.ts b/src/main/persistence.test.ts
index 27563d2bb..7ef005d35 100644
--- a/src/main/persistence.test.ts
+++ b/src/main/persistence.test.ts
@@ -6,6 +6,7 @@ import { writeFileSync, readFileSync, rmSync, mkdtempSync, mkdirSync } from 'fs'
 import { join } from 'path'
 import { tmpdir } from 'os'
 import type { Repo, TerminalTab, WorkspaceSessionState } from '../shared/types'
+import { MAX_BROWSER_HISTORY_ENTRIES } from '../shared/workspace-session-browser-history'
 
 // Shared mutable state so the electron mock can reference a per-test directory
 const testState = { dir: '' }
@@ -113,6 +114,23 @@ function makeSessionWithTerminalBuffers(): WorkspaceSessionState {
   }
 }
 
+function makeSessionWithBrowserHistory(count: number): WorkspaceSessionState {
+  return {
+    activeRepoId: null,
+    activeWorktreeId: null,
+    activeTabId: null,
+    tabsByWorktree: {},
+    terminalLayoutsByTabId: {},
+    browserUrlHistory: Array.from({ length: count }, (_, index) => ({
+      url: `https://example.com/${index}`,
+      normalizedUrl: `https://example.com/${index}`,
+      title: `Example ${index} ${'x'.repeat(200)}`,
+      lastVisitedAt: 1_700_000_000_000 - index,
+      visitCount: 1
+    }))
+  }
+}
+
 describe('Store', () => {
   beforeEach(() => {
     testState.dir = mkdtempSync(join(tmpdir(), 'orca-test-'))
@@ -1037,6 +1055,20 @@ describe('Store', () => {
     })
   })
 
+  it('caps oversized browser history when setting workspace session', async () => {
+    const store = await createStore()
+    const oversizedSession = makeSessionWithBrowserHistory(500)
+    const oversizedBytes = Buffer.byteLength(JSON.stringify(oversizedSession))
+
+    store.setWorkspaceSession(oversizedSession)
+
+    const session = store.getWorkspaceSession()
+    const prunedBytes = Buffer.byteLength(JSON.stringify(session))
+    expect(session.browserUrlHistory).toHaveLength(MAX_BROWSER_HISTORY_ENTRIES)
+    expect(session.browserUrlHistory?.at(-1)?.url).toBe('https://example.com/199')
+    expect(prunedBytes).toBeLessThan(oversizedBytes / 2)
+  })
+
   it('keeps terminal scrollback buffers when the repo catalog is not hydrated yet', async () => {
     const store = await createStore()
 
@@ -1092,6 +1124,23 @@ describe('Store', () => {
     })
   })
 
+  it('caps oversized legacy browser history when loading workspace session', async () => {
+    writeDataFile({
+      schemaVersion: 1,
+      repos: [],
+      worktreeMeta: {},
+      settings: {},
+      ui: {},
+      githubCache: { pr: {}, issue: {} },
+      workspaceSession: makeSessionWithBrowserHistory(500)
+    })
+
+    const store = await createStore()
+    const session = store.getWorkspaceSession()
+    expect(session.browserUrlHistory).toHaveLength(MAX_BROWSER_HISTORY_ENTRIES)
+    expect(session.browserUrlHistory?.at(-1)?.url).toBe('https://example.com/199')
+  })
+
   it('does not restore cleared SSH bindings after a lease expired', async () => {
     const store = await createStore()
     store.upsertSshRemotePtyLease({
diff --git a/src/main/persistence.ts b/src/main/persistence.ts
index 068d33445..3f49a59fc 100644
--- a/src/main/persistence.ts
+++ b/src/main/persistence.ts
@@ -44,6 +44,7 @@ import {
 } from '../shared/constants'
 import { parseWorkspaceSession } from '../shared/workspace-session-schema'
 import { pruneLocalTerminalScrollbackBuffers } from '../shared/workspace-session-terminal-buffers'
+import { pruneWorkspaceSessionBrowserHistory } from '../shared/workspace-session-browser-history'
 import { getRepoIdFromWorktreeId } from '../shared/worktree-id'
 
 function encrypt(plaintext: string): string {
@@ -464,7 +465,9 @@ export class Store {
 
     result = {
       ...result,
-      workspaceSession: pruneLocalTerminalScrollbackBuffers(result.workspaceSession, result.repos)
+      workspaceSession: pruneWorkspaceSessionBrowserHistory(
+        pruneLocalTerminalScrollbackBuffers(result.workspaceSession, result.repos)
+      )
     }
 
     return this.migrateTelemetry(result, fileExistedOnLoad)
@@ -1100,7 +1103,9 @@ export class Store {
   }
 
   setWorkspaceSession(session: PersistedState['workspaceSession']): void {
-    session = pruneLocalTerminalScrollbackBuffers(session, this.state.repos)
+    session = pruneWorkspaceSessionBrowserHistory(
+      pruneLocalTerminalScrollbackBuffers(session, this.state.repos)
+    )
 
     // Why: closes the second half of the SIGKILL race (Issue #217). The
     // renderer's debounced session writer captures its state BEFORE pty:spawn
diff --git a/src/renderer/src/lib/workspace-session-browser-history.test.ts b/src/renderer/src/lib/workspace-session-browser-history.test.ts
new file mode 100644
index 000000000..3d7153f1d
--- /dev/null
+++ b/src/renderer/src/lib/workspace-session-browser-history.test.ts
@@ -0,0 +1,54 @@
+import { describe, expect, it } from 'vitest'
+import type { BrowserHistoryEntry } from '../../../shared/types'
+import { MAX_BROWSER_HISTORY_ENTRIES } from '../../../shared/workspace-session-browser-history'
+import { buildWorkspaceSessionPayload, type WorkspaceSessionSnapshot } from './workspace-session'
+
+function createSnapshot(browserUrlHistory: BrowserHistoryEntry[]): WorkspaceSessionSnapshot {
+  return {
+    activeRepoId: null,
+    activeWorktreeId: null,
+    activeTabId: null,
+    tabsByWorktree: {},
+    terminalLayoutsByTabId: {},
+    activeTabIdByWorktree: {},
+    openFiles: [],
+    activeFileIdByWorktree: {},
+    activeTabTypeByWorktree: {},
+    browserTabsByWorktree: {},
+    browserPagesByWorkspace: {},
+    activeBrowserTabIdByWorktree: {},
+    browserUrlHistory,
+    unifiedTabsByWorktree: {},
+    groupsByWorktree: {},
+    layoutByWorktree: {},
+    activeGroupIdByWorktree: {},
+    sshConnectionStates: new Map(),
+    repos: [],
+    worktreesByRepo: {},
+    lastKnownRelayPtyIdByTabId: {},
+    lastVisitedAtByWorktreeId: {}
+  }
+}
+
+describe('workspace session browser history payloads', () => {
+  it('caps history and reduces serialized bytes at the payload boundary', () => {
+    const oversizedHistory = Array.from({ length: 500 }, (_, index) => ({
+      url: `https://example.com/${index}`,
+      normalizedUrl: `https://example.com/${index}`,
+      title: `${'Search result '.repeat(40)}${index}`,
+      lastVisitedAt: 1_700_000_000_000 - index,
+      visitCount: 1
+    }))
+    const uncappedPayload = {
+      ...buildWorkspaceSessionPayload(createSnapshot([])),
+      browserUrlHistory: oversizedHistory
+    }
+    const payload = buildWorkspaceSessionPayload(createSnapshot(oversizedHistory))
+
+    expect(payload.browserUrlHistory).toHaveLength(MAX_BROWSER_HISTORY_ENTRIES)
+    expect(payload.browserUrlHistory?.at(-1)?.url).toBe('https://example.com/199')
+    expect(Buffer.byteLength(JSON.stringify(payload))).toBeLessThan(
+      Buffer.byteLength(JSON.stringify(uncappedPayload)) / 2
+    )
+  })
+})
diff --git a/src/renderer/src/lib/workspace-session.test.ts b/src/renderer/src/lib/workspace-session.test.ts
index a7416d770..28787da62 100644
--- a/src/renderer/src/lib/workspace-session.test.ts
+++ b/src/renderer/src/lib/workspace-session.test.ts
@@ -82,6 +82,7 @@ function createSnapshot(overrides: Partial<AppState> = {}): AppState {
         }
       ]
     },
+    browserUrlHistory: [],
     ...overrides
   } as AppState
 }
diff --git a/src/renderer/src/lib/workspace-session.ts b/src/renderer/src/lib/workspace-session.ts
index ffaac2f2c..ce8ac84fb 100644
--- a/src/renderer/src/lib/workspace-session.ts
+++ b/src/renderer/src/lib/workspace-session.ts
@@ -6,6 +6,7 @@ import type {
   WorkspaceVisibleTabType
 } from '../../../shared/types'
 import { pruneLocalTerminalScrollbackBuffers } from '../../../shared/workspace-session-terminal-buffers'
+import { normalizeBrowserHistoryEntries } from '../../../shared/workspace-session-browser-history'
 import type { AppState } from '../store'
 import type { OpenFile } from '../store/slices/editor'
 
@@ -264,7 +265,10 @@ export function buildWorkspaceSessionPayload(
       snapshot.browserPagesByWorkspace,
       snapshot.activeBrowserTabIdByWorktree
     ),
-    browserUrlHistory: snapshot.browserUrlHistory,
+    // Why: browser history is user-lifetime state. Enforce the storage cap at
+    // the payload boundary so stale renderer state cannot make every session
+    // write stringify an oversized legacy history array.
+    browserUrlHistory: normalizeBrowserHistoryEntries(snapshot.browserUrlHistory),
     unifiedTabs: unifiedTabsByWorktree,
     tabGroups: groupsByWorktree,
     tabGroupLayouts: layoutByWorktree,
diff --git a/src/renderer/src/store/slices/browser.ts b/src/renderer/src/store/slices/browser.ts
index 92792ab24..d20473c29 100644
--- a/src/renderer/src/store/slices/browser.ts
+++ b/src/renderer/src/store/slices/browser.ts
@@ -14,6 +14,11 @@ import type {
 } from '../../../../shared/types'
 import { ORCA_BROWSER_BLANK_URL } from '../../../../shared/constants'
 import { redactKagiSessionToken } from '../../../../shared/browser-url'
+import {
+  MAX_BROWSER_HISTORY_ENTRIES,
+  normalizeBrowserHistoryEntries,
+  normalizeBrowserHistoryUrl
+} from '../../../../shared/workspace-session-browser-history'
 import { pickNeighbor } from './tab-group-state'
 import { destroyWorkspaceWebviews } from './browser-webview-cleanup'
 
@@ -138,38 +143,6 @@ export type BrowserSlice = {
   setDefaultBrowserSessionProfileId: (profileId: string | null) => void
 }
 
-const MAX_BROWSER_HISTORY_ENTRIES = 200
-
-function normalizeHistoryUrl(url: string): string {
-  try {
-    const parsed = new URL(redactKagiSessionToken(url))
-    parsed.hostname = parsed.hostname.toLowerCase()
-    parsed.protocol = parsed.protocol.toLowerCase()
-    let normalized = parsed.toString()
-    if (normalized.endsWith('/')) {
-      normalized = normalized.slice(0, -1)
-    }
-    return normalized
-  } catch {
-    return redactKagiSessionToken(url).toLowerCase()
-  }
-}
-
-function deduplicateHistory(entries: BrowserHistoryEntry[]): BrowserHistoryEntry[] {
-  const seen = new Set<string>()
-  const deduped: BrowserHistoryEntry[] = []
-  for (const entry of entries) {
-    const safeUrl = redactKagiSessionToken(entry.url)
-    const key = normalizeHistoryUrl(safeUrl)
-    if (seen.has(key)) {
-      continue
-    }
-    seen.add(key)
-    deduped.push({ ...entry, url: safeUrl, normalizedUrl: key })
-  }
-  return deduped.slice(0, MAX_BROWSER_HISTORY_ENTRIES)
-}
-
 function normalizeUrl(url: string): string {
   const trimmed = url.trim()
   if (trimmed.length === 0) {
@@ -1268,7 +1241,7 @@ export const createBrowserSlice: StateCreator<AppState, [], [], BrowserSlice> =
         activeBrowserTabId,
         activeTabTypeByWorktree: nextActiveTabTypeByWorktree,
         activeTabType,
-        browserUrlHistory: deduplicateHistory(session.browserUrlHistory ?? [])
+        browserUrlHistory: normalizeBrowserHistoryEntries(session.browserUrlHistory ?? [])
       }
     })
 
@@ -1494,7 +1467,7 @@ export const createBrowserSlice: StateCreator<AppState, [], [], BrowserSlice> =
     if (safeUrl === ORCA_BROWSER_BLANK_URL || safeUrl === 'about:blank' || !safeUrl) {
       return
     }
-    const normalized = normalizeHistoryUrl(safeUrl)
+    const normalized = normalizeBrowserHistoryUrl(safeUrl)
     set((s) => {
       const existing = s.browserUrlHistory.find((entry) => entry.normalizedUrl === normalized)
       let next: BrowserHistoryEntry[] = existing
diff --git a/src/shared/workspace-session-browser-history.ts b/src/shared/workspace-session-browser-history.ts
new file mode 100644
index 000000000..fd2e484d0
--- /dev/null
+++ b/src/shared/workspace-session-browser-history.ts
@@ -0,0 +1,55 @@
+import type { BrowserHistoryEntry, WorkspaceSessionState } from './types'
+import { redactKagiSessionToken } from './browser-url'
+
+export const MAX_BROWSER_HISTORY_ENTRIES = 200
+
+export function normalizeBrowserHistoryUrl(url: string): string {
+  try {
+    const parsed = new URL(redactKagiSessionToken(url))
+    parsed.hostname = parsed.hostname.toLowerCase()
+    parsed.protocol = parsed.protocol.toLowerCase()
+    let normalized = parsed.toString()
+    if (normalized.endsWith('/')) {
+      normalized = normalized.slice(0, -1)
+    }
+    return normalized
+  } catch {
+    return redactKagiSessionToken(url).toLowerCase()
+  }
+}
+
+export function normalizeBrowserHistoryEntries(
+  entries: readonly BrowserHistoryEntry[]
+): BrowserHistoryEntry[] {
+  const seen = new Set<string>()
+  const normalizedEntries: BrowserHistoryEntry[] = []
+  for (const entry of entries) {
+    const safeUrl = redactKagiSessionToken(entry.url)
+    const key = normalizeBrowserHistoryUrl(safeUrl)
+    if (seen.has(key)) {
+      continue
+    }
+    seen.add(key)
+    normalizedEntries.push({ ...entry, url: safeUrl, normalizedUrl: key })
+    if (normalizedEntries.length >= MAX_BROWSER_HISTORY_ENTRIES) {
+      break
+    }
+  }
+  return normalizedEntries
+}
+
+export function pruneWorkspaceSessionBrowserHistory(
+  session: WorkspaceSessionState
+): WorkspaceSessionState {
+  if (!session.browserUrlHistory) {
+    return session
+  }
+  const browserUrlHistory = normalizeBrowserHistoryEntries(session.browserUrlHistory)
+  if (
+    browserUrlHistory.length === session.browserUrlHistory.length &&
+    browserUrlHistory.every((entry, index) => entry === session.browserUrlHistory?.[index])
+  ) {
+    return session
+  }
+  return { ...session, browserUrlHistory }
+}
diff --git a/src/shared/workspace-session-schema.test.ts b/src/shared/workspace-session-schema.test.ts
index 4a25933f4..0bcc95b48 100644
--- a/src/shared/workspace-session-schema.test.ts
+++ b/src/shared/workspace-session-schema.test.ts
@@ -1,5 +1,6 @@
 import { describe, it, expect } from 'vitest'
 import { parseWorkspaceSession } from './workspace-session-schema'
+import { MAX_BROWSER_HISTORY_ENTRIES } from './workspace-session-browser-history'
 
 describe('parseWorkspaceSession', () => {
   it('accepts a minimal valid session', () => {
@@ -116,4 +117,27 @@ describe('parseWorkspaceSession', () => {
       expect(result.value.lastVisitedAtByWorktreeId).toEqual({ good: 1_700_000_000_000 })
     }
   })
+
+  it('caps oversized browser history while parsing legacy workspace sessions', () => {
+    const result = parseWorkspaceSession({
+      activeRepoId: null,
+      activeWorktreeId: null,
+      activeTabId: null,
+      tabsByWorktree: {},
+      terminalLayoutsByTabId: {},
+      browserUrlHistory: Array.from({ length: 500 }, (_, index) => ({
+        url: `https://example.com/${index}`,
+        normalizedUrl: `https://example.com/${index}`,
+        title: `Example ${index}`,
+        lastVisitedAt: 1_700_000_000_000 - index,
+        visitCount: 1
+      }))
+    })
+
+    expect(result.ok).toBe(true)
+    if (result.ok) {
+      expect(result.value.browserUrlHistory).toHaveLength(MAX_BROWSER_HISTORY_ENTRIES)
+      expect(result.value.browserUrlHistory?.at(-1)?.url).toBe('https://example.com/199')
+    }
+  })
 })
diff --git a/src/shared/workspace-session-schema.ts b/src/shared/workspace-session-schema.ts
index 66b1f3b3c..cb17b297a 100644
--- a/src/shared/workspace-session-schema.ts
+++ b/src/shared/workspace-session-schema.ts
@@ -15,6 +15,7 @@ import type {
   TerminalPaneLayoutNode,
   WorkspaceSessionState
 } from './types'
+import { normalizeBrowserHistoryEntries } from './workspace-session-browser-history'
 
 // ─── Terminal pane layout (recursive) ───────────────────────────────
 
@@ -182,6 +183,10 @@ const browserHistoryEntrySchema = z.object({
   visitCount: z.number()
 })
 
+const browserHistoryEntriesSchema = z
+  .array(browserHistoryEntrySchema)
+  .transform((entries) => normalizeBrowserHistoryEntries(entries))
+
 // ─── Workspace session ──────────────────────────────────────────────
 
 export const workspaceSessionStateSchema: z.ZodType<WorkspaceSessionState> = z.object({
@@ -197,7 +202,7 @@ export const workspaceSessionStateSchema: z.ZodType<WorkspaceSessionState> = z.o
   browserPagesByWorkspace: z.record(z.string(), z.array(browserPageSchema)).optional(),
   activeBrowserTabIdByWorktree: z.record(z.string(), z.string().nullable()).optional(),
   activeTabTypeByWorktree: z.record(z.string(), workspaceVisibleTabTypeSchema).optional(),
-  browserUrlHistory: z.array(browserHistoryEntrySchema).optional(),
+  browserUrlHistory: browserHistoryEntriesSchema.optional(),
   activeTabIdByWorktree: z.record(z.string(), z.string().nullable()).optional(),
   unifiedTabs: z.record(z.string(), z.array(tabSchema)).optional(),
   tabGroups: z.record(z.string(), z.array(tabGroupSchema)).optional(),