diff --git a/dist/cli/config-writer.d.ts b/dist/cli/config-writer.d.ts
index eed01c1..552dfbb 100644
--- a/dist/cli/config-writer.d.ts
+++ b/dist/cli/config-writer.d.ts
@@ -14,6 +14,17 @@
 export declare function resolveConfigPath(startDir?: string): string;
 export declare function isGlobalConfigPath(configPath: string): boolean;
 export declare function writeDisabledRules(configPath: string, disabledRules: string[]): void;
+/**
+ * Writes the top-level toggles (enabled, mode, external rules source) the
+ * settings panel owns. An empty externalRulesJsonPath means "use the
+ * built-in default list", so the key is removed rather than written as "".
+ */
+export declare function writeSettings(configPath: string, settings: {
+    enabled: boolean;
+    mode: string;
+    externalRulesMode: string;
+    externalRulesJsonPath: string;
+}): void;
 /**
  * Merges the given keys into the config file, preserving every other key and
  * the sort order the UI sends. Allowlist entries are written in the order the
diff --git a/dist/cli/config-writer.js b/dist/cli/config-writer.js
index 3268f11..f10c76c 100644
--- a/dist/cli/config-writer.js
+++ b/dist/cli/config-writer.js
@@ -24,6 +24,19 @@ export function isGlobalConfigPath(configPath) {
 export function writeDisabledRules(configPath, disabledRules) {
     writeConfigKeys(configPath, { disabledRules: [...disabledRules].sort() });
 }
+/**
+ * Writes the top-level toggles (enabled, mode, external rules source) the
+ * settings panel owns. An empty externalRulesJsonPath means "use the
+ * built-in default list", so the key is removed rather than written as "".
+ */
+export function writeSettings(configPath, settings) {
+    writeConfigKeys(configPath, {
+        enabled: settings.enabled,
+        mode: settings.mode,
+        externalRulesMode: settings.externalRulesMode,
+        externalRulesJsonPath: settings.externalRulesJsonPath || undefined,
+    });
+}
 /**
  * Merges the given keys into the config file, preserving every other key and
  * the sort order the UI sends. Allowlist entries are written in the order the
diff --git a/dist/cli/page.d.ts b/dist/cli/page.d.ts
index 0fbc1ef..afc861a 100644
--- a/dist/cli/page.d.ts
+++ b/dist/cli/page.d.ts
@@ -16,4 +16,10 @@ export interface Allowlists {
     allowedValues: string[];
     allowedPatterns: string[];
 }
-export declare function renderPage(rules: RuleRow[], allowlists: Allowlists, token: string, configPath: string, isGlobal: boolean): string;
+export interface Settings {
+    enabled: boolean;
+    mode: string;
+    externalRulesMode: string;
+    externalRulesJsonPath: string;
+}
+export declare function renderPage(rules: RuleRow[], allowlists: Allowlists, settings: Settings, token: string, configPath: string, isGlobal: boolean): string;
diff --git a/dist/cli/page.js b/dist/cli/page.js
index 73d7905..0140243 100644
--- a/dist/cli/page.js
+++ b/dist/cli/page.js
@@ -3,9 +3,10 @@
  * logo, which the server serves from the local-only /logo.png route - no
  * external CDNs or network calls.
  */
-export function renderPage(rules, allowlists, token, configPath, isGlobal) {
+export function renderPage(rules, allowlists, settings, token, configPath, isGlobal) {
     const rulesJson = JSON.stringify(rules).replace(/</g, '\\u003c');
     const allowlistsJson = JSON.stringify(allowlists).replace(/</g, '\\u003c');
+    const settingsJson = JSON.stringify(settings).replace(/</g, '\\u003c');
     const scopeLabel = isGlobal
         ? 'Global config - applies to every project unless it has its own .privacy-guard.json'
         : 'Project-level override';
@@ -58,6 +59,16 @@ export function renderPage(rules, allowlists, token, configPath, isGlobal) {
   .adder button:hover:not(:disabled) { background: #8881; }
   .adder button:disabled { opacity: 0.45; cursor: not-allowed; }
   .field-error { flex-basis: 100%; font-size: 0.8rem; color: #dc2626; }
+  .setting { margin-bottom: 1.5rem; max-width: 560px; }
+  .setting label.title { display: block; font-weight: 600; margin-bottom: 0.25rem; }
+  .setting .hint { font-size: 0.8rem; color: #888; margin: 0.15rem 0 0.5rem; }
+  .setting select, .setting input[type="text"] { padding: 0.45rem 0.65rem; border-radius: 6px; border: 1px solid #8888; font-size: 0.9rem; font: inherit; background: none; color: inherit; min-width: 220px; }
+  .setting input[type="text"] { width: 100%; font-family: ui-monospace, monospace; }
+  .setting-toggle { display: flex; align-items: center; gap: 0.6rem; }
+  .setting-toggle label.title { margin-bottom: 0; }
+  .mode-options { display: flex; flex-direction: column; gap: 0.4rem; }
+  .mode-options label { display: flex; align-items: flex-start; gap: 0.5rem; cursor: pointer; font-weight: normal; }
+  .mode-options .mode-desc { color: #888; font-size: 0.8rem; }
 </style>
 </head>
 <body>
@@ -68,12 +79,46 @@ export function renderPage(rules, allowlists, token, configPath, isGlobal) {
   <div class="subtitle">${escapeHtml(scopeLabel)}<br>Config: <code>${escapeHtml(configPath)}</code> - every change saves automatically</div>
 
   <div class="tabs" role="tablist">
-    <button role="tab" id="tab-rules" aria-selected="true" aria-controls="panel-rules">Rules</button>
+    <button role="tab" id="tab-settings" aria-selected="true" aria-controls="panel-settings">Settings</button>
+    <button role="tab" id="tab-rules" aria-selected="false" aria-controls="panel-rules">Rules</button>
     <button role="tab" id="tab-allowlists" aria-selected="false" aria-controls="panel-allowlists">Allowlists</button>
     <span id="status"></span>
   </div>
 
-  <div class="panel" id="panel-rules" role="tabpanel">
+  <div class="panel" id="panel-settings" role="tabpanel">
+    <div class="setting setting-toggle">
+      <input type="checkbox" id="setting-enabled">
+      <label class="title" for="setting-enabled">Privacy Guard enabled</label>
+    </div>
+    <p class="hint" style="margin-top: -1rem;">Turns scanning off entirely for this config's scope. Rule and allowlist changes below still save, they just stop applying.</p>
+
+    <div class="setting">
+      <span class="title">Mode</span>
+      <p class="hint">What happens when a finding is detected in a prompt.</p>
+      <div class="mode-options">
+        <label><input type="radio" name="mode" value="block"> <span>Block <span class="mode-desc">- stop the prompt from reaching Claude; you must remove or allowlist the finding first.</span></span></label>
+        <label><input type="radio" name="mode" value="redact"> <span>Redact <span class="mode-desc">- still blocks the prompt (the hook API can't resubmit it for you), but the block message includes a cleaned, copy-pasteable version with findings replaced by placeholders.</span></span></label>
+        <label><input type="radio" name="mode" value="warn"> <span>Warn <span class="mode-desc">- let the prompt through unchanged, just report what was found.</span></span></label>
+      </div>
+    </div>
+
+    <div class="setting">
+      <label class="title" for="setting-external-mode">External rule set</label>
+      <p class="hint">The bundled regex list (data/regex_list_1.json) ships far more patterns than coding secrets. "Coding-only" keeps just the ones relevant to source code and shell input; "All" also enables the broader PII/compliance-oriented patterns.</p>
+      <select id="setting-external-mode">
+        <option value="coding-only">Coding-only</option>
+        <option value="all">All</option>
+      </select>
+    </div>
+
+    <div class="setting">
+      <label class="title" for="setting-external-path">External rules JSON path</label>
+      <p class="hint">Absolute path to a custom regex list, in place of the bundled default. Leave blank to use the built-in list. Changing this only affects the rule list shown here after restarting the editor.</p>
+      <input type="text" id="setting-external-path" placeholder="(bundled default)">
+    </div>
+  </div>
+
+  <div class="panel" id="panel-rules" role="tabpanel" hidden>
     <div class="toolbar">
       <input type="search" id="search" placeholder="Filter by id, title, or category...">
     </div>
@@ -120,6 +165,7 @@ export function renderPage(rules, allowlists, token, configPath, isGlobal) {
 <script>
 const RULES = ${rulesJson};
 const ALLOWLISTS = ${allowlistsJson};
+const SETTINGS = ${settingsJson};
 const TOKEN = ${JSON.stringify(token)};
 const state = new Map(RULES.map(r => [r.id, !r.disabled]));
 
@@ -225,6 +271,63 @@ for (const tab of document.querySelectorAll('[role="tab"]')) {
   });
 }
 
+// ---- Settings ----
+
+const enabledCb = document.getElementById('setting-enabled');
+const externalModeSel = document.getElementById('setting-external-mode');
+const externalPathInput = document.getElementById('setting-external-path');
+
+enabledCb.checked = SETTINGS.enabled;
+externalModeSel.value = SETTINGS.externalRulesMode;
+externalPathInput.value = SETTINGS.externalRulesJsonPath;
+for (const radio of document.querySelectorAll('input[name="mode"]')) {
+  radio.checked = radio.value === SETTINGS.mode;
+}
+
+let settingsSaveTimer = null;
+function scheduleSaveSettings() {
+  clearTimeout(settingsSaveTimer);
+  settingsSaveTimer = setTimeout(saveSettings, 300);
+}
+
+enabledCb.addEventListener('change', scheduleSaveSettings);
+externalModeSel.addEventListener('change', scheduleSaveSettings);
+externalPathInput.addEventListener('input', scheduleSaveSettings);
+for (const radio of document.querySelectorAll('input[name="mode"]')) {
+  radio.addEventListener('change', scheduleSaveSettings);
+}
+
+let settingsSaveInFlight = false;
+let settingsSaveAgain = false;
+
+async function saveSettings() {
+  if (settingsSaveInFlight) {
+    settingsSaveAgain = true;
+    return;
+  }
+  settingsSaveInFlight = true;
+  const mode = document.querySelector('input[name="mode"]:checked').value;
+  const payload = {
+    enabled: enabledCb.checked,
+    mode,
+    externalRulesMode: externalModeSel.value,
+    externalRulesJsonPath: externalPathInput.value.trim(),
+  };
+  setStatus('Saving...', '');
+  try {
+    await postJson('/save-settings', payload);
+    setStatus('Saved settings.', 'ok');
+  } catch (err) {
+    setStatus('Error: ' + err.message, 'err');
+  } finally {
+    settingsSaveInFlight = false;
+    if (settingsSaveAgain) {
+      settingsSaveAgain = false;
+      saveSettings();
+    }
+  }
+}
+
 // ---- Allowlists ----
 
 const LIST_LABELS = {
diff --git a/dist/cli/server.js b/dist/cli/server.js
index 3412d2c..5a551d0 100644
--- a/dist/cli/server.js
+++ b/dist/cli/server.js
@@ -12,8 +12,8 @@ import { fileURLToPath } from 'url';
 import { BUILTIN_RULES, loadExternalRulesFromJson } from '../scanner/detectors.js';
 import { ConfigLoader } from '../config/loader.js';
 import { renderPage } from './page.js';
-import { resolveConfigPath, isGlobalConfigPath, writeDisabledRules, writeAllowlists } from './config-writer.js';
-import { parseAllowlists, validateAllowedPattern } from './validate.js';
+import { resolveConfigPath, isGlobalConfigPath, writeDisabledRules, writeAllowlists, writeSettings } from './config-writer.js';
+import { parseAllowlists, validateAllowedPattern, parseSettings } from './validate.js';
 const INACTIVITY_TIMEOUT_MS = 10 * 60 * 1000;
 export async function startRulesServer() {
     const configPath = resolveConfigPath();
@@ -39,13 +39,19 @@ export async function startRulesServer() {
         allowedValues: [...config.allowedValues],
         allowedPatterns: [...config.allowedPatterns],
     };
+    const settings = {
+        enabled: config.enabled,
+        mode: config.mode,
+        externalRulesMode: config.externalRulesMode ?? 'coding-only',
+        externalRulesJsonPath: config.externalRulesJsonPath ?? '',
+    };
     const logoPath = fileURLToPath(new URL('../../assets/claude-code-privacy-guard-logo.png', import.meta.url));
     const token = randomBytes(16).toString('hex');
     const server = http.createServer((req, res) => {
         resetInactivityTimer();
         if (req.method === 'GET' && req.url === '/') {
             res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
-            res.end(renderPage(rules, allowlists, token, configPath, isGlobalConfigPath(configPath)));
+            res.end(renderPage(rules, allowlists, settings, token, configPath, isGlobalConfigPath(configPath)));
             return;
         }
         if (req.method === 'GET' && req.url === '/logo.png') {
@@ -92,6 +98,24 @@ export async function startRulesServer() {
             });
             return;
         }
+        if (req.method === 'POST' && req.url === '/save-settings') {
+            readJsonBody(req, res, (parsed) => {
+                if (parsed.token !== token) {
+                    res.writeHead(403, { 'Content-Type': 'application/json' });
+                    res.end(JSON.stringify({ ok: false, error: 'Invalid token' }));
+                    return;
+                }
+                const next = parseSettings(parsed);
+                writeSettings(configPath, next);
+                settings.enabled = next.enabled;
+                settings.mode = next.mode;
+                settings.externalRulesMode = next.externalRulesMode;
+                settings.externalRulesJsonPath = next.externalRulesJsonPath;
+                res.writeHead(200, { 'Content-Type': 'application/json' });
+                res.end(JSON.stringify({ ok: true, settings: next }));
+            });
+            return;
+        }
         // Live feedback for the regex field so a bad pattern is caught while
         // typing, using the exact check the scanner applies at load time.
         if (req.method === 'POST' && req.url === '/validate-pattern') {
diff --git a/dist/cli/validate.d.ts b/dist/cli/validate.d.ts
index 009ca25..6bc2948 100644
--- a/dist/cli/validate.d.ts
+++ b/dist/cli/validate.d.ts
@@ -4,11 +4,28 @@
  * warning nobody sees), so the UI validates up front instead - a pattern that
  * would be silently dropped should never make it into the config file.
  */
+import { PromptGuardMode } from '../types/findings.js';
 export interface AllowlistPayload {
     allowedDomains: string[];
     allowedValues: string[];
     allowedPatterns: string[];
 }
+export interface SettingsPayload {
+    enabled: boolean;
+    mode: PromptGuardMode;
+    externalRulesMode: 'coding-only' | 'all';
+    externalRulesJsonPath: string;
+}
+/**
+ * Validates and normalizes the /save-settings payload. Throws on anything
+ * invalid so a failed save leaves the existing config untouched.
+ */
+export declare function parseSettings(input: {
+    enabled?: unknown;
+    mode?: unknown;
+    externalRulesMode?: unknown;
+    externalRulesJsonPath?: unknown;
+}): SettingsPayload;
 /**
  * Returns an error message for a single allowedPatterns entry, or null when
  * it's fine. Mirrors ScannerEngine.compileAllowedPatterns so the UI accepts
diff --git a/dist/cli/validate.js b/dist/cli/validate.js
index e572ef5..1b2b725 100644
--- a/dist/cli/validate.js
+++ b/dist/cli/validate.js
@@ -5,6 +5,33 @@
  * would be silently dropped should never make it into the config file.
  */
 import safeRegex from 'safe-regex2';
+const VALID_MODES = ['block', 'redact', 'warn'];
+const VALID_EXTERNAL_RULES_MODES = ['coding-only', 'all'];
+/**
+ * Validates and normalizes the /save-settings payload. Throws on anything
+ * invalid so a failed save leaves the existing config untouched.
+ */
+export function parseSettings(input) {
+    if (typeof input.enabled !== 'boolean') {
+        throw new Error('enabled must be a boolean');
+    }
+    if (typeof input.mode !== 'string' || !VALID_MODES.includes(input.mode)) {
+        throw new Error(`mode must be one of ${VALID_MODES.join(', ')}`);
+    }
+    if (typeof input.externalRulesMode !== 'string' ||
+        !VALID_EXTERNAL_RULES_MODES.includes(input.externalRulesMode)) {
+        throw new Error(`externalRulesMode must be one of ${VALID_EXTERNAL_RULES_MODES.join(', ')}`);
+    }
+    if (typeof input.externalRulesJsonPath !== 'string') {
+        throw new Error('externalRulesJsonPath must be a string');
+    }
+    return {
+        enabled: input.enabled,
+        mode: input.mode,
+        externalRulesMode: input.externalRulesMode,
+        externalRulesJsonPath: input.externalRulesJsonPath.trim(),
+    };
+}
 /**
  * Returns an error message for a single allowedPatterns entry, or null when
  * it's fine. Mirrors ScannerEngine.compileAllowedPatterns so the UI accepts
diff --git a/src/cli/config-writer.ts b/src/cli/config-writer.ts
index 50125b1..b77a1cc 100644
--- a/src/cli/config-writer.ts
+++ b/src/cli/config-writer.ts
@@ -29,6 +29,28 @@ export function writeDisabledRules(configPath: string, disabledRules: string[]):
   writeConfigKeys(configPath, { disabledRules: [...disabledRules].sort() });
 }
 
+/**
+ * Writes the top-level toggles (enabled, mode, external rules source) the
+ * settings panel owns. An empty externalRulesJsonPath means "use the
+ * built-in default list", so the key is removed rather than written as "".
+ */
+export function writeSettings(
+  configPath: string,
+  settings: {
+    enabled: boolean;
+    mode: string;
+    externalRulesMode: string;
+    externalRulesJsonPath: string;
+  }
+): void {
+  writeConfigKeys(configPath, {
+    enabled: settings.enabled,
+    mode: settings.mode,
+    externalRulesMode: settings.externalRulesMode,
+    externalRulesJsonPath: settings.externalRulesJsonPath || undefined,
+  });
+}
+
 /**
  * Merges the given keys into the config file, preserving every other key and
  * the sort order the UI sends. Allowlist entries are written in the order the
diff --git a/src/cli/page.ts b/src/cli/page.ts
index 8a16d01..ee68e97 100644
--- a/src/cli/page.ts
+++ b/src/cli/page.ts
@@ -19,15 +19,24 @@ export interface Allowlists {
   allowedPatterns: string[];
 }
 
+export interface Settings {
+  enabled: boolean;
+  mode: string;
+  externalRulesMode: string;
+  externalRulesJsonPath: string;
+}
+
 export function renderPage(
   rules: RuleRow[],
   allowlists: Allowlists,
+  settings: Settings,
   token: string,
   configPath: string,
   isGlobal: boolean
 ): string {
   const rulesJson = JSON.stringify(rules).replace(/</g, '\\u003c');
   const allowlistsJson = JSON.stringify(allowlists).replace(/</g, '\\u003c');
+  const settingsJson = JSON.stringify(settings).replace(/</g, '\\u003c');
   const scopeLabel = isGlobal
     ? 'Global config - applies to every project unless it has its own .privacy-guard.json'
     : 'Project-level override';
@@ -81,6 +90,16 @@ export function renderPage(
   .adder button:hover:not(:disabled) { background: #8881; }
   .adder button:disabled { opacity: 0.45; cursor: not-allowed; }
   .field-error { flex-basis: 100%; font-size: 0.8rem; color: #dc2626; }
+  .setting { margin-bottom: 1.5rem; max-width: 560px; }
+  .setting label.title { display: block; font-weight: 600; margin-bottom: 0.25rem; }
+  .setting .hint { font-size: 0.8rem; color: #888; margin: 0.15rem 0 0.5rem; }
+  .setting select, .setting input[type="text"] { padding: 0.45rem 0.65rem; border-radius: 6px; border: 1px solid #8888; font-size: 0.9rem; font: inherit; background: none; color: inherit; min-width: 220px; }
+  .setting input[type="text"] { width: 100%; font-family: ui-monospace, monospace; }
+  .setting-toggle { display: flex; align-items: center; gap: 0.6rem; }
+  .setting-toggle label.title { margin-bottom: 0; }
+  .mode-options { display: flex; flex-direction: column; gap: 0.4rem; }
+  .mode-options label { display: flex; align-items: flex-start; gap: 0.5rem; cursor: pointer; font-weight: normal; }
+  .mode-options .mode-desc { color: #888; font-size: 0.8rem; }
 </style>
 </head>
 <body>
@@ -91,12 +110,46 @@ export function renderPage(
   <div class="subtitle">${escapeHtml(scopeLabel)}<br>Config: <code>${escapeHtml(configPath)}</code> - every change saves automatically</div>
 
   <div class="tabs" role="tablist">
-    <button role="tab" id="tab-rules" aria-selected="true" aria-controls="panel-rules">Rules</button>
+    <button role="tab" id="tab-settings" aria-selected="true" aria-controls="panel-settings">Settings</button>
+    <button role="tab" id="tab-rules" aria-selected="false" aria-controls="panel-rules">Rules</button>
     <button role="tab" id="tab-allowlists" aria-selected="false" aria-controls="panel-allowlists">Allowlists</button>
     <span id="status"></span>
   </div>
 
-  <div class="panel" id="panel-rules" role="tabpanel">
+  <div class="panel" id="panel-settings" role="tabpanel">
+    <div class="setting setting-toggle">
+      <input type="checkbox" id="setting-enabled">
+      <label class="title" for="setting-enabled">Privacy Guard enabled</label>
+    </div>
+    <p class="hint" style="margin-top: -1rem;">Turns scanning off entirely for this config's scope. Rule and allowlist changes below still save, they just stop applying.</p>
+
+    <div class="setting">
+      <span class="title">Mode</span>
+      <p class="hint">What happens when a finding is detected in a prompt.</p>
+      <div class="mode-options">
+        <label><input type="radio" name="mode" value="block"> <span>Block <span class="mode-desc">- stop the prompt from reaching Claude; you must remove or allowlist the finding first.</span></span></label>
+        <label><input type="radio" name="mode" value="redact"> <span>Redact <span class="mode-desc">- still blocks the prompt (the hook API can't resubmit it for you), but the block message includes a cleaned, copy-pasteable version with findings replaced by placeholders.</span></span></label>
+        <label><input type="radio" name="mode" value="warn"> <span>Warn <span class="mode-desc">- let the prompt through unchanged, just report what was found.</span></span></label>
+      </div>
+    </div>
+
+    <div class="setting">
+      <label class="title" for="setting-external-mode">External rule set</label>
+      <p class="hint">The bundled regex list (data/regex_list_1.json) ships far more patterns than coding secrets. "Coding-only" keeps just the ones relevant to source code and shell input; "All" also enables the broader PII/compliance-oriented patterns.</p>
+      <select id="setting-external-mode">
+        <option value="coding-only">Coding-only</option>
+        <option value="all">All</option>
+      </select>
+    </div>
+
+    <div class="setting">
+      <label class="title" for="setting-external-path">External rules JSON path</label>
+      <p class="hint">Absolute path to a custom regex list, in place of the bundled default. Leave blank to use the built-in list. Changing this only affects the rule list shown here after restarting the editor.</p>
+      <input type="text" id="setting-external-path" placeholder="(bundled default)">
+    </div>
+  </div>
+
+  <div class="panel" id="panel-rules" role="tabpanel" hidden>
     <div class="toolbar">
       <input type="search" id="search" placeholder="Filter by id, title, or category...">
     </div>
@@ -143,6 +196,7 @@ export function renderPage(
 <script>
 const RULES = ${rulesJson};
 const ALLOWLISTS = ${allowlistsJson};
+const SETTINGS = ${settingsJson};
 const TOKEN = ${JSON.stringify(token)};
 const state = new Map(RULES.map(r => [r.id, !r.disabled]));
 
@@ -248,6 +302,63 @@ for (const tab of document.querySelectorAll('[role="tab"]')) {
   });
 }
 
+// ---- Settings ----
+
+const enabledCb = document.getElementById('setting-enabled');
+const externalModeSel = document.getElementById('setting-external-mode');
+const externalPathInput = document.getElementById('setting-external-path');
+
+enabledCb.checked = SETTINGS.enabled;
+externalModeSel.value = SETTINGS.externalRulesMode;
+externalPathInput.value = SETTINGS.externalRulesJsonPath;
+for (const radio of document.querySelectorAll('input[name="mode"]')) {
+  radio.checked = radio.value === SETTINGS.mode;
+}
+
+let settingsSaveTimer = null;
+function scheduleSaveSettings() {
+  clearTimeout(settingsSaveTimer);
+  settingsSaveTimer = setTimeout(saveSettings, 300);
+}
+
+enabledCb.addEventListener('change', scheduleSaveSettings);
+externalModeSel.addEventListener('change', scheduleSaveSettings);
+externalPathInput.addEventListener('input', scheduleSaveSettings);
+for (const radio of document.querySelectorAll('input[name="mode"]')) {
+  radio.addEventListener('change', scheduleSaveSettings);
+}
+
+let settingsSaveInFlight = false;
+let settingsSaveAgain = false;
+
+async function saveSettings() {
+  if (settingsSaveInFlight) {
+    settingsSaveAgain = true;
+    return;
+  }
+  settingsSaveInFlight = true;
+  const mode = document.querySelector('input[name="mode"]:checked').value;
+  const payload = {
+    enabled: enabledCb.checked,
+    mode,
+    externalRulesMode: externalModeSel.value,
+    externalRulesJsonPath: externalPathInput.value.trim(),
+  };
+  setStatus('Saving...', '');
+  try {
+    await postJson('/save-settings', payload);
+    setStatus('Saved settings.', 'ok');
+  } catch (err) {
+    setStatus('Error: ' + err.message, 'err');
+  } finally {
+    settingsSaveInFlight = false;
+    if (settingsSaveAgain) {
+      settingsSaveAgain = false;
+      saveSettings();
+    }
+  }
+}
+
 // ---- Allowlists ----
 
 const LIST_LABELS = {
diff --git a/src/cli/server.ts b/src/cli/server.ts
index 88f2536..0f4553b 100644
--- a/src/cli/server.ts
+++ b/src/cli/server.ts
@@ -14,8 +14,8 @@ import { fileURLToPath } from 'url';
 import { BUILTIN_RULES, loadExternalRulesFromJson } from '../scanner/detectors.js';
 import { ConfigLoader } from '../config/loader.js';
 import { renderPage, RuleRow } from './page.js';
-import { resolveConfigPath, isGlobalConfigPath, writeDisabledRules, writeAllowlists } from './config-writer.js';
-import { parseAllowlists, validateAllowedPattern, AllowlistPayload } from './validate.js';
+import { resolveConfigPath, isGlobalConfigPath, writeDisabledRules, writeAllowlists, writeSettings } from './config-writer.js';
+import { parseAllowlists, validateAllowedPattern, parseSettings, AllowlistPayload } from './validate.js';
 
 const INACTIVITY_TIMEOUT_MS = 10 * 60 * 1000;
 
@@ -47,6 +47,13 @@ export async function startRulesServer(): Promise<void> {
     allowedPatterns: [...config.allowedPatterns],
   };
 
+  const settings = {
+    enabled: config.enabled,
+    mode: config.mode,
+    externalRulesMode: config.externalRulesMode ?? 'coding-only',
+    externalRulesJsonPath: config.externalRulesJsonPath ?? '',
+  };
+
   const logoPath = fileURLToPath(new URL('../../assets/claude-code-privacy-guard-logo.png', import.meta.url));
 
   const token = randomBytes(16).toString('hex');
@@ -56,7 +63,7 @@ export async function startRulesServer(): Promise<void> {
 
     if (req.method === 'GET' && req.url === '/') {
       res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
-      res.end(renderPage(rules, allowlists, token, configPath, isGlobalConfigPath(configPath)));
+      res.end(renderPage(rules, allowlists, settings, token, configPath, isGlobalConfigPath(configPath)));
       return;
     }
 
@@ -109,6 +116,27 @@ export async function startRulesServer(): Promise<void> {
       return;
     }
 
+    if (req.method === 'POST' && req.url === '/save-settings') {
+      readJsonBody(req, res, (parsed) => {
+        if (parsed.token !== token) {
+          res.writeHead(403, { 'Content-Type': 'application/json' });
+          res.end(JSON.stringify({ ok: false, error: 'Invalid token' }));
+          return;
+        }
+
+        const next = parseSettings(parsed);
+        writeSettings(configPath, next);
+        settings.enabled = next.enabled;
+        settings.mode = next.mode;
+        settings.externalRulesMode = next.externalRulesMode;
+        settings.externalRulesJsonPath = next.externalRulesJsonPath;
+
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ ok: true, settings: next }));
+      });
+      return;
+    }
+
     // Live feedback for the regex field so a bad pattern is caught while
     // typing, using the exact check the scanner applies at load time.
     if (req.method === 'POST' && req.url === '/validate-pattern') {
diff --git a/src/cli/validate.ts b/src/cli/validate.ts
index 8a7e992..55b601d 100644
--- a/src/cli/validate.ts
+++ b/src/cli/validate.ts
@@ -6,6 +6,7 @@
  */
 
 import safeRegex from 'safe-regex2';
+import { PromptGuardMode } from '../types/findings.js';
 
 export interface AllowlistPayload {
   allowedDomains: string[];
@@ -13,6 +14,50 @@ export interface AllowlistPayload {
   allowedPatterns: string[];
 }
 
+const VALID_MODES: PromptGuardMode[] = ['block', 'redact', 'warn'];
+const VALID_EXTERNAL_RULES_MODES = ['coding-only', 'all'];
+
+export interface SettingsPayload {
+  enabled: boolean;
+  mode: PromptGuardMode;
+  externalRulesMode: 'coding-only' | 'all';
+  externalRulesJsonPath: string;
+}
+
+/**
+ * Validates and normalizes the /save-settings payload. Throws on anything
+ * invalid so a failed save leaves the existing config untouched.
+ */
+export function parseSettings(input: {
+  enabled?: unknown;
+  mode?: unknown;
+  externalRulesMode?: unknown;
+  externalRulesJsonPath?: unknown;
+}): SettingsPayload {
+  if (typeof input.enabled !== 'boolean') {
+    throw new Error('enabled must be a boolean');
+  }
+  if (typeof input.mode !== 'string' || !VALID_MODES.includes(input.mode as PromptGuardMode)) {
+    throw new Error(`mode must be one of ${VALID_MODES.join(', ')}`);
+  }
+  if (
+    typeof input.externalRulesMode !== 'string' ||
+    !VALID_EXTERNAL_RULES_MODES.includes(input.externalRulesMode)
+  ) {
+    throw new Error(`externalRulesMode must be one of ${VALID_EXTERNAL_RULES_MODES.join(', ')}`);
+  }
+  if (typeof input.externalRulesJsonPath !== 'string') {
+    throw new Error('externalRulesJsonPath must be a string');
+  }
+
+  return {
+    enabled: input.enabled,
+    mode: input.mode as PromptGuardMode,
+    externalRulesMode: input.externalRulesMode as 'coding-only' | 'all',
+    externalRulesJsonPath: input.externalRulesJsonPath.trim(),
+  };
+}
+
 /**
  * Returns an error message for a single allowedPatterns entry, or null when
  * it's fine. Mirrors ScannerEngine.compileAllowedPatterns so the UI accepts