diff --git a/CLAUDE.md b/CLAUDE.md
index 19814ad8..a65d18d5 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -692,6 +692,167 @@ The `<.pagination>` component (defined in `CoreComponents`) accepts:
 - The component handles URL building automatically - just provide the base path and params
 - See `lib/towerops_web/live/admin/dashboard_live.ex` for a complete example
 
+### Browser Navigation and URL State Management
+
+**Critical Requirement:** All LiveViews MUST properly handle browser back/forward buttons by syncing UI state to URL parameters.
+
+**The Idiomatic Phoenix Pattern:**
+
+Use Phoenix LiveView's built-in `push_patch/2` and `handle_params/3` - no custom helpers needed.
+
+**Core Principle:** URL is the single source of truth for all visible state (tabs, modals, filters, pagination).
+
+#### Pattern 1: Tab Navigation
+
+**LiveView:**
+```elixir
+@impl true
+def handle_params(params, _url, socket) do
+  # Validate params - never trust user input
+  tab = case params["tab"] do
+    tab when tab in ~w(overview sensors interfaces) -> tab
+    _ -> "overview"  # Safe default
+  end
+
+  {:noreply, socket
+    |> assign(:active_tab, tab)
+    |> load_tab_data(tab)}
+end
+
+def handle_event("select_tab", %{"tab" => tab}, socket) do
+  # Update URL with push_patch - handle_params will update assigns
+  {:noreply, push_patch(socket, to: ~p"/devices/#{socket.assigns.device.id}?tab=#{tab}")}
+end
+```
+
+**Template:**
+```heex
+<.link patch={~p"/devices/#{@device.id}?tab=overview"}
+       class={if @active_tab == "overview", do: "active", else: ""}>
+  Overview
+</.link>
+```
+
+#### Pattern 2: Modal State
+
+**LiveView:**
+```elixir
+@impl true
+def handle_params(params, _url, socket) do
+  modal = params["modal"]
+
+  {:noreply, socket
+    |> assign(:show_modal, modal != nil)
+    |> assign(:modal_name, modal)
+    |> maybe_initialize_form(modal)}
+end
+
+def handle_event("show_add_token", _params, socket) do
+  {:noreply, push_patch(socket, to: ~p"/settings?modal=add_token")}
+end
+
+def handle_event("save_token", %{"token" => attrs}, socket) do
+  case Accounts.create_api_token(attrs) do
+    {:ok, _token} ->
+      {:noreply, socket
+        |> put_flash(:info, "Token created")
+        |> push_patch(to: ~p"/settings")}  # Closes modal by removing ?modal
+
+    {:error, changeset} ->
+      {:noreply, assign(socket, :form, to_form(changeset))}
+  end
+end
+```
+
+**Template:**
+```heex
+<.button phx-click="show_add_token">Add API Token</.button>
+
+<.modal :if={@show_modal && @modal_name == "add_token"}
+        id="add-token-modal"
+        on_cancel={JS.patch(~p"/settings")}>
+  <.simple_form for={@form} phx-submit="save_token">
+    <!-- form fields -->
+  </.simple_form>
+</.modal>
+```
+
+#### Pattern 3: Filters with Pagination
+
+**LiveView:**
+```elixir
+@impl true
+def handle_params(params, _url, socket) do
+  filter = case params["filter"] do
+    f when f in ~w(active resolved all) -> f
+    _ -> "active"
+  end
+
+  page = params["page"] || "1" |> String.to_integer()
+
+  {:noreply, socket
+    |> assign(:filter, filter)
+    |> assign(:page, page)
+    |> load_alerts(filter, page)}
+end
+
+def handle_event("apply_filters", %{"filter" => filter}, socket) do
+  # Reset to page 1 when filter changes
+  {:noreply, push_patch(socket, to: ~p"/alerts?filter=#{filter}&page=1")}
+end
+```
+
+**Template:**
+```heex
+<form phx-change="apply_filters">
+  <.input name="filter" value={@filter} options={[...]} />
+</form>
+
+<!-- Pagination component preserves filter param -->
+<.pagination
+  meta={@pagination}
+  path={~p"/alerts"}
+  params={%{"filter" => @filter}}
+/>
+```
+
+#### Critical Rules
+
+1. **Every LiveView must implement `handle_params/3`**
+   - This is the ONLY place that reads URL params and updates assigns
+   - Validate all params - never trust user input
+   - Provide sensible defaults for missing/invalid params
+
+2. **Never use `assign` for URL-backed state**
+   - ❌ `assign(socket, :active_tab, "sensors")`
+   - ✅ `push_patch(socket, to: ~p"/path?tab=sensors")`
+   - Let `handle_params/3` update assigns after URL changes
+
+3. **Use Phoenix built-in navigation**
+   - Event handlers: `push_patch(socket, to: ~p"/path?param=value")`
+   - Templates: `<.link patch={~p"/path?param=value"}>...</.link>`
+   - Modal cancel: `on_cancel={JS.patch(~p"/path")}`
+
+4. **Test browser back/forward**
+   - Click through tabs/filters
+   - Press browser back - should return to previous state
+   - Press browser forward - should restore next state
+   - Refresh page - should preserve state from URL
+
+#### What This Achieves
+
+✅ Browser back button returns to previous tab/filter/modal state
+✅ Browser forward button restores next state
+✅ Page refresh preserves state from URL
+✅ Bookmarkable URLs share exact application state
+✅ Deep linking works correctly
+
+#### References
+
+- [Phoenix LiveView Live Navigation Guide](https://hexdocs.pm/phoenix_live_view/live-navigation.html)
+- [Persistent Forms with URL on LiveView](https://fly.io/phoenix-files/persistent-forms-with-your-url-on-liveview/)
+- Design document: `docs/plans/2026-02-12-browser-navigation-fix-design.md`
+
 ## Testing Patterns
 
 ### SNMP Mocking with Mox
diff --git a/docs/plans/2026-02-12-browser-navigation-fix-design.md b/docs/plans/2026-02-12-browser-navigation-fix-design.md
new file mode 100644
index 00000000..7e496131
--- /dev/null
+++ b/docs/plans/2026-02-12-browser-navigation-fix-design.md
@@ -0,0 +1,314 @@
+# Browser Back/Forward Navigation Fix - Design Document
+
+**Date:** 2026-02-12
+**Status:** Approved
+**Goal:** Ensure browser back/forward buttons work correctly across all LiveView pages
+
+## Problem Statement
+
+18 LiveViews in the application don't properly sync UI state to URL parameters, causing browser back/forward buttons to not work as expected. Users cannot navigate back through tab changes, modal opens/closes, or filter selections.
+
+## Root Causes
+
+1. **Missing `handle_params/3` callbacks** - 18 LiveViews lack this required callback
+2. **State changes via `assign` only** - Event handlers update assigns without updating URL
+3. **No URL synchronization** - Tabs, modals, filters change without `push_patch/2`
+4. **Cookie consent forced reload** - JavaScript breaks navigation flow
+
+## Solution: The Idiomatic Phoenix Pattern
+
+Use Phoenix LiveView's built-in `push_patch/2` and `handle_params/3` pattern. No custom helpers needed.
+
+### Core Architecture
+
+**Principle:** URL is the single source of truth for all visible state.
+
+**Flow:**
+```
+User interaction (click tab, open modal)
+  → Event handler calls push_patch(socket, to: ~p"/path?param=value")
+  → Browser URL updates
+  → handle_params/3 receives new params
+  → Validates params, updates assigns
+  → Minimal diff sent to client
+  → UI updates
+```
+
+**Browser back/forward:**
+```
+User clicks browser back
+  → Browser navigates to previous URL
+  → handle_params/3 receives previous params
+  → Assigns update to previous state
+  → UI restores previous state
+```
+
+## Implementation Patterns
+
+### Pattern 1: Tab Navigation
+
+**LiveView:**
+```elixir
+@impl true
+def handle_params(params, _url, socket) do
+  tab = case params["tab"] do
+    tab when tab in ~w(overview sensors interfaces) -> tab
+    _ -> "overview"  # Default
+  end
+
+  {:noreply, socket
+    |> assign(:active_tab, tab)
+    |> load_tab_data(tab)}
+end
+
+def handle_event("select_tab", %{"tab" => tab}, socket) do
+  {:noreply, push_patch(socket, to: ~p"/devices/#{socket.assigns.device.id}?tab=#{tab}")}
+end
+```
+
+**Template:**
+```heex
+<.link patch={~p"/devices/#{@device.id}?tab=overview"}
+       class={if @active_tab == "overview", do: "active", else: ""}>
+  Overview
+</.link>
+```
+
+### Pattern 2: Modal State
+
+**LiveView:**
+```elixir
+@impl true
+def handle_params(params, _url, socket) do
+  modal = params["modal"]
+
+  {:noreply, socket
+    |> assign(:show_modal, modal != nil)
+    |> assign(:modal_name, modal)
+    |> maybe_initialize_form(modal)}
+end
+
+def handle_event("show_add_token", _params, socket) do
+  {:noreply, push_patch(socket, to: ~p"/settings?modal=add_token")}
+end
+
+def handle_event("save_token", %{"token" => attrs}, socket) do
+  case Accounts.create_api_token(attrs) do
+    {:ok, _token} ->
+      {:noreply, socket
+        |> put_flash(:info, "Token created")
+        |> push_patch(to: ~p"/settings")}  # Closes modal
+
+    {:error, changeset} ->
+      {:noreply, assign(socket, :form, to_form(changeset))}
+  end
+end
+```
+
+**Template:**
+```heex
+<.button phx-click="show_add_token">Add API Token</.button>
+
+<.modal :if={@show_modal && @modal_name == "add_token"}
+        id="add-token-modal"
+        on_cancel={JS.patch(~p"/settings")}>
+  <.simple_form for={@form} phx-submit="save_token">
+    <!-- form fields -->
+  </.simple_form>
+</.modal>
+```
+
+### Pattern 3: Filters + Pagination
+
+**LiveView:**
+```elixir
+@impl true
+def handle_params(params, _url, socket) do
+  filter = case params["filter"] do
+    f when f in ~w(active resolved all) -> f
+    _ -> "active"
+  end
+
+  page = params["page"] || "1" |> String.to_integer()
+
+  {:noreply, socket
+    |> assign(:filter, filter)
+    |> assign(:page, page)
+    |> load_alerts(filter, page)}
+end
+
+def handle_event("apply_filters", %{"filter" => filter}, socket) do
+  # Reset to page 1 when filter changes
+  {:noreply, push_patch(socket, to: ~p"/alerts?filter=#{filter}&page=1")}
+end
+```
+
+**Template:**
+```heex
+<form phx-change="apply_filters">
+  <.input name="filter" value={@filter} options={[...]} />
+</form>
+
+<.pagination meta={@pagination} path={~p"/alerts"} params={%{"filter" => @filter}} />
+```
+
+## Migration Strategy
+
+### The 18 LiveViews to Update
+
+**Priority 1: High-traffic user-facing (5 LiveViews)**
+1. `DashboardLive` - Main landing page
+2. `NetworkMapLive` - Topology view with tabs
+3. `AlertLive.Index` - Alerts with filters
+4. `UserSettingsLive` - Settings with modals
+5. `DeviceLive.Show` - Device details (add modal state)
+
+**Priority 2: Admin and specialized (8 LiveViews)**
+6. `Admin.MonitoringLive`
+7. `Admin.DashboardLive`
+8. `AgentLive.Index`
+9. `AgentLive.Show`
+10. `SiteLive.Index`
+11. `SiteLive.Show`
+12. `OrganizationLive.Index`
+13. `BackupLive.*` (multiple)
+
+**Priority 3: Auth and low-traffic (5 LiveViews)**
+14. `MobileQrLive`
+15. `OrgLive.New`
+16. `UserRegistrationLive`
+17. `UserResetPasswordLive`
+18. `Account.TotpEnrollment`
+19. `Account.Activity`
+20. `Account.MyData`
+
+### Update Checklist Per LiveView
+
+```markdown
+- [ ] 1. Read current implementation
+- [ ] 2. Identify stateful UI elements (tabs, modals, filters, pagination)
+- [ ] 3. Add/update `handle_params/3`:
+  - [ ] Validate params with whitelist
+  - [ ] Provide sensible defaults
+  - [ ] Update assigns from params only
+- [ ] 4. Update event handlers:
+  - [ ] Replace `assign` with `push_patch` for state changes
+  - [ ] Preserve existing params when adding new ones
+- [ ] 5. Update templates:
+  - [ ] Use `<.link patch={...}>` for navigation
+  - [ ] Use `JS.patch(...)` in modal `on_cancel`
+- [ ] 6. Test manually:
+  - [ ] Navigate through states
+  - [ ] Press back - returns to previous state
+  - [ ] Press forward - restores next state
+  - [ ] Refresh page - state preserved
+```
+
+### Batch Timeline
+
+- **Days 1-2:** Priority 1 (high-traffic user-facing)
+- **Days 3-4:** Priority 2 (admin/specialized)
+- **Day 5:** Priority 3 (auth/low-traffic)
+- **Day 6:** Cookie consent fix, final testing
+
+Each batch is a separate commit with manual testing before proceeding.
+
+## Testing Strategy
+
+### Manual Testing Protocol
+
+For each LiveView:
+
+**Tab Navigation Test:**
+1. Load page → verify default tab in URL (?tab=default)
+2. Click Tab 2 → verify URL updates (?tab=tab2)
+3. Browser back → verify returns to Tab 1
+4. Browser forward → verify returns to Tab 2
+5. Refresh → verify stays on current tab
+
+**Modal State Test:**
+1. Open modal → verify ?modal=name in URL
+2. Browser back → verify modal closes
+3. Browser forward → verify modal reopens
+4. Cancel button → verify modal closes and ?modal= removed
+5. Copy URL with ?modal → paste in new tab → modal opens
+
+**Filter + Pagination Test:**
+1. Change filter → verify ?filter=value&page=1
+2. Navigate to page 3 → verify ?filter=value&page=3
+3. Browser back → verify returns to page 1 with filter
+4. Change filter → verify resets to page 1
+5. Bookmark URL → reopen → verify state restored
+
+### Automated Testing
+
+**LiveView Test Pattern:**
+```elixir
+defmodule ToweropsWeb.DeviceLiveTest do
+  use ToweropsWeb.ConnCase
+  import Phoenix.LiveViewTest
+
+  describe "browser history with tabs" do
+    test "navigating tabs updates URL", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/devices/#{device}")
+
+      # Click sensors tab
+      view |> element("a", "Sensors") |> render_click()
+      assert_patch(view, ~p"/devices/#{device}?tab=sensors")
+
+      # Simulate back button
+      {:ok, view, _html} = live(conn, ~p"/devices/#{device}?tab=overview")
+      assert has_element?(view, "[data-active-tab='overview']")
+    end
+
+    test "handles invalid tab param", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/devices/#{device}?tab=invalid")
+      assert has_element?(view, "[data-active-tab='overview']")
+    end
+  end
+end
+```
+
+## Cookie Consent Fix
+
+**File:** `assets/js/cookie_consent.js`
+
+**Problem:**
+```javascript
+window.location.href = location.href;  // Forces reload, breaks history
+```
+
+**Fix:**
+```javascript
+// Remove the reload line - LiveView handles state updates
+```
+
+**Test:**
+1. Accept cookies → no page reload
+2. Navigate away and back → cookies still accepted
+3. Browser back → smooth navigation
+
+## Key Principles
+
+1. **URL is source of truth** - All visible state must be in URL params
+2. **Never trust params** - Always validate in `handle_params/3`
+3. **Use Phoenix built-ins** - `push_patch/2`, `<.link patch={...}>`, `JS.patch(...)`
+4. **No custom abstractions** - Phoenix provides everything needed
+5. **Test back/forward** - Manual testing is critical for UX validation
+
+## Success Criteria
+
+✅ Browser back button returns to previous tab/filter/modal state
+✅ Browser forward button restores next state
+✅ Page refresh preserves state from URL
+✅ Bookmarked URLs restore exact application state
+✅ All 18 LiveViews implement `handle_params/3`
+✅ Automated tests verify URL state synchronization
+✅ Cookie consent doesn't break navigation
+
+## References
+
+- [Phoenix LiveView Live Navigation Guide](https://hexdocs.pm/phoenix_live_view/live-navigation.html)
+- [Persistent Forms with URL on LiveView](https://fly.io/phoenix-files/persistent-forms-with-your-url-on-liveview/)
+- Phoenix LiveView `push_patch/2` documentation
+- Phoenix LiveView `handle_params/3` documentation