diff --git a/src/main/browser-manager.ts b/src/main/browser-manager.ts
index 0bc698bf..3a282937 100644
--- a/src/main/browser-manager.ts
+++ b/src/main/browser-manager.ts
@@ -5,6 +5,7 @@ import { join, resolve, sep } from "node:path";
 import log from "electron-log/main.js";
 import type { BrowserAction, BrowserActionResult, QueuedAction } from "./browser/browser-types";
 import { getPlatformRules, attachWindowSecurity, assertAllowedUrl, waitForLoad, runAction } from "./browser/browser-action-executor";
+import { hasAuthenticatedCookie } from "./browser/browser-action-auth";
 
 export type { BrowserAction, BrowserActionResult } from "./browser/browser-types";
 
@@ -242,7 +243,7 @@ export class BrowserManager {
         }
       }),
     );
-    const hasCookies = cookieSets.some((cookies) => cookies.length > 0);
+    const hasCookies = hasAuthenticatedCookie(cookieSets, rules.authenticatedCookieNames);
     if (!hasCookies) {
       return false;
     }
diff --git a/src/main/browser/browser-action-auth.ts b/src/main/browser/browser-action-auth.ts
new file mode 100644
index 00000000..81aca311
--- /dev/null
+++ b/src/main/browser/browser-action-auth.ts
@@ -0,0 +1,49 @@
+import type { Session } from "electron";
+import { browserNotLoggedIn } from "./browser-action-errors";
+import { getPlatformRules } from "./browser-url-helpers";
+
+type CookieLike = {
+  name?: string;
+};
+
+export async function assertAuthenticatedSession(
+  session: Pick<Session, "cookies">,
+  platform: string,
+  actionType: string,
+): Promise<void> {
+  const rules = getPlatformRules(platform);
+  const cookieSets = await Promise.all(
+    rules.cookieOrigins.map((origin) => session.cookies.get({ url: origin }).catch(() => [])),
+  );
+  if (!hasAuthenticatedCookie(cookieSets, rules.authenticatedCookieNames)) {
+    throw browserNotLoggedIn(platform, actionType);
+  }
+}
+
+export function hasAuthenticatedCookie(
+  cookieSets: readonly (readonly CookieLike[])[],
+  authenticatedCookieNames?: readonly string[],
+): boolean {
+  if (!authenticatedCookieNames || authenticatedCookieNames.length === 0) {
+    return cookieSets.some((cookies) => cookies.length > 0);
+  }
+  const expectedNames = new Set(authenticatedCookieNames.map((name) => name.toLowerCase()));
+  return cookieSets.some((cookies) =>
+    cookies.some((cookie) => cookie.name && expectedNames.has(cookie.name.toLowerCase())),
+  );
+}
+
+export async function assertAuthenticatedPage(
+  getUrl: () => string,
+  platform: string,
+  actionType: string,
+): Promise<void> {
+  const finalUrl = getUrl().toLowerCase();
+  const rules = getPlatformRules(platform);
+  const bouncedToLogin = rules.unauthenticatedUrlMarkers.some((marker) =>
+    finalUrl.includes(marker.toLowerCase()),
+  );
+  if (bouncedToLogin) {
+    throw browserNotLoggedIn(platform, actionType);
+  }
+}
diff --git a/src/main/browser/browser-action-cdp.ts b/src/main/browser/browser-action-cdp.ts
new file mode 100644
index 00000000..57721abf
--- /dev/null
+++ b/src/main/browser/browser-action-cdp.ts
@@ -0,0 +1,251 @@
+import type { WebContents } from "electron";
+import { browserNotLoggedIn, browserSelectorDrift, browserVerificationFailed } from "./browser-action-errors";
+import { isAppError } from "../errors/index.js";
+
+type RuntimeEvaluateResult = {
+  result?: { value?: unknown };
+  exceptionDetails?: { text?: string };
+};
+
+type ElementProbe = {
+  selector: string;
+  x: number;
+  y: number;
+  text: string;
+};
+
+const POLL_INTERVAL_MS = 250;
+
+export class BrowserCdpClient {
+  private attachedByClient = false;
+  private retryCount = 0;
+
+  constructor(
+    private readonly webContents: WebContents,
+    private readonly platform: string,
+    private readonly actionType: string,
+  ) {}
+
+  async attach(): Promise<void> {
+    if (this.webContents.debugger.isAttached()) return;
+    this.webContents.debugger.attach("1.3");
+    this.attachedByClient = true;
+  }
+
+  async dispose(): Promise<void> {
+    if (this.attachedByClient && this.webContents.debugger.isAttached()) {
+      this.webContents.debugger.detach();
+    }
+  }
+
+  getRetryCount(): number {
+    return this.retryCount;
+  }
+
+  async evaluate<T>(expression: string): Promise<T> {
+    await this.attach();
+    const response = await this.webContents.debugger.sendCommand("Runtime.evaluate", {
+      expression,
+      awaitPromise: true,
+      returnByValue: true,
+    }) as RuntimeEvaluateResult;
+    if (response.exceptionDetails) {
+      throw browserVerificationFailed(
+        this.platform,
+        this.actionType,
+        response.exceptionDetails.text ?? "runtime evaluation failed",
+      );
+    }
+    return response.result?.value as T;
+  }
+
+  async clickFirst(candidates: readonly string[], selectorKey: string, timeoutMs = 10_000): Promise<string> {
+    const element = await this.waitForElement(candidates, selectorKey, timeoutMs);
+    await this.webContents.debugger.sendCommand("Input.dispatchMouseEvent", {
+      type: "mouseMoved",
+      x: element.x,
+      y: element.y,
+      button: "none",
+    });
+    await this.webContents.debugger.sendCommand("Input.dispatchMouseEvent", {
+      type: "mousePressed",
+      x: element.x,
+      y: element.y,
+      button: "left",
+      clickCount: 1,
+    });
+    await this.webContents.debugger.sendCommand("Input.dispatchMouseEvent", {
+      type: "mouseReleased",
+      x: element.x,
+      y: element.y,
+      button: "left",
+      clickCount: 1,
+    });
+    return element.selector;
+  }
+
+  async clickOptional(candidates: readonly string[], selectorKey: string, timeoutMs = 1_500): Promise<string | null> {
+    try {
+      return await this.clickFirst(candidates, selectorKey, timeoutMs);
+    } catch (error) {
+      if (!isAppError(error) || error.code !== "browser.selector_drift") throw error;
+      return null;
+    }
+  }
+
+  async waitForFirst(candidates: readonly string[], selectorKey: string, timeoutMs = 10_000): Promise<string> {
+    return (await this.waitForElement(candidates, selectorKey, timeoutMs)).selector;
+  }
+
+  async waitForAuthenticatedSurface(
+    candidates: readonly string[],
+    authenticatedCookieNames?: readonly string[],
+    timeoutMs = 5_000,
+  ): Promise<string> {
+    const deadline = Date.now() + timeoutMs;
+    while (Date.now() < deadline) {
+      const selector = await this.evaluate<string | null>(
+        buildAuthenticatedSurfaceExpression(candidates, authenticatedCookieNames ?? []),
+      );
+      if (selector) return selector;
+      this.retryCount += 1;
+      await delay(POLL_INTERVAL_MS);
+    }
+    throw browserNotLoggedIn(this.platform, this.actionType);
+  }
+
+  async focusAndType(candidates: readonly string[], text: string, selectorKey: string): Promise<string> {
+    const selector = await this.clickFirst(candidates, selectorKey);
+    await this.webContents.debugger.sendCommand("Input.insertText", { text });
+    return selector;
+  }
+
+  async waitForText(
+    candidates: readonly string[],
+    expectedText: string,
+    timeoutMs = 12_000,
+  ): Promise<void> {
+    const fingerprint = expectedText.trim().slice(0, 40);
+    if (fingerprint.length === 0) {
+      throw browserVerificationFailed(this.platform, this.actionType, "empty text fingerprint");
+    }
+    const deadline = Date.now() + timeoutMs;
+    while (Date.now() < deadline) {
+      const matched = await this.evaluate<boolean>(buildTextMatchExpression(candidates, fingerprint));
+      if (matched) return;
+      this.retryCount += 1;
+      await delay(POLL_INTERVAL_MS);
+    }
+    throw browserVerificationFailed(this.platform, this.actionType, `text not found after submit: ${fingerprint}`);
+  }
+
+  async waitForAnyText(candidates: readonly string[], timeoutMs = 10_000): Promise<string[]> {
+    const deadline = Date.now() + timeoutMs;
+    while (Date.now() < deadline) {
+      const texts = await this.evaluate<string[]>(buildVisibleTextsExpression(candidates));
+      if (texts.length > 0) return texts;
+      this.retryCount += 1;
+      await delay(POLL_INTERVAL_MS);
+    }
+    throw browserSelectorDrift(this.platform, this.actionType, "content_items");
+  }
+
+  private async waitForElement(
+    candidates: readonly string[],
+    selectorKey: string,
+    timeoutMs: number,
+  ): Promise<ElementProbe> {
+    const deadline = Date.now() + timeoutMs;
+    while (Date.now() < deadline) {
+      const element = await this.evaluate<ElementProbe | null>(buildElementProbeExpression(candidates));
+      if (element) return element;
+      this.retryCount += 1;
+      await delay(POLL_INTERVAL_MS);
+    }
+    throw browserSelectorDrift(this.platform, this.actionType, selectorKey);
+  }
+}
+
+function buildElementProbeExpression(candidates: readonly string[]): string {
+  return `(() => {
+    const candidates = ${JSON.stringify(candidates)};
+    for (const selector of candidates) {
+      const elements = Array.from(document.querySelectorAll(selector));
+      for (const element of elements) {
+        const rect = element.getBoundingClientRect();
+        const style = window.getComputedStyle(element);
+        const disabled = element.disabled === true || element.getAttribute("aria-disabled") === "true";
+        if (rect.width <= 0 || rect.height <= 0 || style.visibility === "hidden" || style.display === "none" || disabled) continue;
+        element.scrollIntoView({ block: "center", inline: "center" });
+        const nextRect = element.getBoundingClientRect();
+        return {
+          selector,
+          x: nextRect.left + nextRect.width / 2,
+          y: nextRect.top + nextRect.height / 2,
+          text: (element.innerText || element.textContent || "").slice(0, 200)
+        };
+      }
+    }
+    return null;
+  })()`;
+}
+
+function buildTextMatchExpression(candidates: readonly string[], fingerprint: string): string {
+  return `(() => {
+    const candidates = ${JSON.stringify(candidates)};
+    const fingerprint = ${JSON.stringify(fingerprint)};
+    for (const selector of candidates) {
+      for (const element of Array.from(document.querySelectorAll(selector))) {
+        const text = element.innerText || element.textContent || "";
+        if (text.includes(fingerprint)) return true;
+      }
+    }
+    return false;
+  })()`;
+}
+
+function buildVisibleTextsExpression(candidates: readonly string[]): string {
+  return `(() => {
+    const out = [];
+    const candidates = ${JSON.stringify(candidates)};
+    for (const selector of candidates) {
+      for (const element of Array.from(document.querySelectorAll(selector))) {
+        const rect = element.getBoundingClientRect();
+        if (rect.width <= 0 || rect.height <= 0) continue;
+        const text = (element.innerText || element.textContent || "").trim();
+        if (text.length > 0) out.push(text.slice(0, 300));
+        if (out.length >= 20) return out;
+      }
+    }
+    return out;
+  })()`;
+}
+
+function buildAuthenticatedSurfaceExpression(
+  candidates: readonly string[],
+  authenticatedCookieNames: readonly string[],
+): string {
+  return `(() => {
+    const candidates = ${JSON.stringify(candidates)};
+    for (const selector of candidates) {
+      for (const element of Array.from(document.querySelectorAll(selector))) {
+        const rect = element.getBoundingClientRect();
+        const style = window.getComputedStyle(element);
+        if (rect.width <= 0 || rect.height <= 0 || style.visibility === "hidden" || style.display === "none") continue;
+        return selector;
+      }
+    }
+    const cookie = document.cookie || "";
+    const authenticatedCookieNames = ${JSON.stringify(authenticatedCookieNames.map((name) => name.toLowerCase()))};
+    if (authenticatedCookieNames.length === 0 && cookie.trim().length > 0) return "document.cookie";
+    const cookieNames = new Set(cookie.split(";").map((part) => part.split("=")[0]?.trim().toLowerCase()).filter(Boolean));
+    for (const name of authenticatedCookieNames) {
+      if (cookieNames.has(name)) return "document.cookie:" + name;
+    }
+    return null;
+  })()`;
+}
+
+function delay(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
diff --git a/src/main/browser/browser-action-errors.ts b/src/main/browser/browser-action-errors.ts
new file mode 100644
index 00000000..224f0709
--- /dev/null
+++ b/src/main/browser/browser-action-errors.ts
@@ -0,0 +1,33 @@
+import { RecoverableError, UpstreamError, UserInputError } from "../errors/index.js";
+
+export function browserNotLoggedIn(platform: string, actionType: string): UserInputError {
+  return new UserInputError({
+    code: "browser.not_logged_in",
+    message: `${platform} session is not authenticated for ${actionType}.`,
+    context: { platform, actionType },
+  });
+}
+
+export function browserSelectorDrift(
+  platform: string,
+  actionType: string,
+  selectorKey: string,
+): UpstreamError {
+  return new UpstreamError({
+    code: "browser.selector_drift",
+    message: `${platform} selector set did not expose ${selectorKey} for ${actionType}.`,
+    context: { platform, actionType, selectorKey },
+  });
+}
+
+export function browserVerificationFailed(
+  platform: string,
+  actionType: string,
+  expectation: string,
+): RecoverableError {
+  return new RecoverableError({
+    code: "browser.verification_failed",
+    message: `${platform} ${actionType} did not pass verification: ${expectation}.`,
+    context: { platform, actionType, expectation },
+  });
+}
diff --git a/src/main/browser/browser-action-executor.ts b/src/main/browser/browser-action-executor.ts
index 8363c182..24914756 100644
--- a/src/main/browser/browser-action-executor.ts
+++ b/src/main/browser/browser-action-executor.ts
@@ -3,25 +3,86 @@ import { existsSync, writeFileSync } from "node:fs";
 import type { NativeImage } from "electron";
 import log from "electron-log/main.js";
 import type { BrowserAction, BrowserActionResult } from "./browser-types";
-import { assertAllowedUrl, attachWindowSecurity, getComposeUrl, getFeedUrl, getSearchUrl } from "./browser-url-helpers";
+import {
+  assertAllowedUrl,
+  attachWindowSecurity,
+  getComposeUrl,
+  getFeedUrl,
+  getPlatformRules,
+  getSearchUrl,
+} from "./browser-url-helpers";
+import { BrowserCdpClient } from "./browser-action-cdp";
+import { assertAuthenticatedPage, assertAuthenticatedSession } from "./browser-action-auth";
+import { getPlatformSelectors } from "./platform-selectors";
+import type { PlatformSelectors } from "./platform-selectors";
+import { browserVerificationFailed } from "./browser-action-errors";
+import { isAppError } from "../errors/index.js";
 
 export { getPlatformRules, assertAllowedUrl, attachWindowSecurity } from "./browser-url-helpers";
 
+type BrowserActionOutcome =
+  | "success"
+  | "logged_out"
+  | "selector_drift"
+  | "network"
+  | "rate_limited"
+  | "cancelled"
+  | "verification_failed";
+
+interface BrowserActionTelemetry {
+  platform: string;
+  action_type: string;
+  selector_hit: string | null;
+  selector_hits: string[];
+  retries: number;
+  duration_ms: number;
+  final_outcome: BrowserActionOutcome;
+}
+
 export function delay(ms: number): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, ms));
 }
 
-export function waitForLoad(win: BrowserWindow, timeoutMs = 15000): Promise<void> {
-  return new Promise((resolve) => {
-    if (win.webContents.isLoading()) {
-      const timer = setTimeout(resolve, timeoutMs);
-      win.webContents.once("did-finish-load", () => {
-        clearTimeout(timer);
-        resolve();
-      });
-    } else {
+export function waitForLoad(
+  win: BrowserWindow,
+  timeoutMs = 15000,
+  context: { platform: string; actionType: string } = { platform: "browser", actionType: "load" },
+): Promise<void> {
+  return new Promise((resolve, reject) => {
+    if (!win.webContents.isLoading()) {
       resolve();
+      return;
     }
+
+    const cleanup = () => {
+      clearTimeout(timer);
+      win.webContents.off("did-finish-load", onFinish);
+      win.webContents.off("did-fail-load", onFail);
+      win.off("closed", onClosed);
+    };
+    const fail = (expectation: string) => {
+      cleanup();
+      reject(browserVerificationFailed(context.platform, context.actionType, expectation));
+    };
+    const onFinish = () => {
+      cleanup();
+      resolve();
+    };
+    const onFail = (
+      _event: Electron.Event,
+      errorCode: number,
+      errorDescription: string,
+      _validatedUrl: string,
+      isMainFrame: boolean,
+    ) => {
+      if (isMainFrame) fail(`page load failed: ${errorDescription} (${errorCode})`);
+    };
+    const onClosed = () => fail("window closed during page load");
+    const timer = setTimeout(() => fail(`page load exceeded ${timeoutMs}ms`), timeoutMs);
+
+    win.webContents.once("did-finish-load", onFinish);
+    win.webContents.on("did-fail-load", onFail);
+    win.once("closed", onClosed);
   });
 }
 
@@ -35,6 +96,8 @@ export async function runAction(
   const payload = action.payload;
   const screenshotPath = `${screenshotDir}/${action.id}.png`;
   const platform = action.platform;
+  const startedAt = Date.now();
+  const selectorHits: string[] = [];
 
   log.info(`[browser] Executing ${action.actionType} for ${platform}/${action.socialAccountId}`);
 
@@ -54,233 +117,106 @@ export async function runAction(
   attachWindowSecurity(win, platform);
   win.setMenuBarVisibility(false);
 
+  const cdp = new BrowserCdpClient(win.webContents, platform, action.actionType);
+  const selectors = getPlatformSelectors(platform);
+  const assertNotCancelled = () => {
+    if (cancelledActionIds.has(action.id)) {
+      throw new Error("BROWSER_ACTION_CANCELLED");
+    }
+  };
+  const remember = (selector: string | null) => {
+    if (selector) selectorHits.push(selector);
+  };
+
   try {
+    assertNotCancelled();
+    await assertAuthenticatedSession(session, platform, action.actionType);
     let summary = "Action completed";
-    const assertNotCancelled = () => {
-      if (cancelledActionIds.has(action.id)) {
-        throw new Error("BROWSER_ACTION_CANCELLED");
-      }
-    };
 
     switch (action.actionType) {
       case "navigate": {
-        assertNotCancelled();
-        const url = String(payload.url || "https://google.com");
-        assertAllowedUrl(platform, url, "navigate");
-        await win.loadURL(url);
-        await waitForLoad(win);
-        assertNotCancelled();
-        const title = await win.webContents.executeJavaScript("document.title");
+        const url = String(payload.url || getFeedUrl(platform));
+        await loadActionUrl(win, platform, action.actionType, url);
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        const title = await cdp.evaluate<string>("document.title");
         summary = `Navigated to ${title}`;
         break;
       }
 
       case "post": {
+        const content = requirePayloadText(payload.content, "content");
+        await loadActionUrl(win, platform, action.actionType, getComposeUrl(platform));
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        remember(await cdp.clickOptional(selectors.composerOpen, "composer_open"));
+        remember(await cdp.focusAndType(selectors.editor, content, "editor"));
         assertNotCancelled();
-        const content = String(payload.content || "");
-        const postUrl = getComposeUrl(platform);
-        await win.loadURL(postUrl);
-        await waitForLoad(win);
-        await delay(2000);
-        assertNotCancelled();
-
-        if (platform === "twitter") {
-          // Use clipboard-based approach since Twitter's React editor ignores execCommand
-          await win.webContents.executeJavaScript(`
-            (async () => {
-              const editor = document.querySelector('[data-testid="tweetTextarea_0"], [role="textbox"][contenteditable="true"]');
-              if (!editor) return;
-              editor.focus();
-              const dt = new DataTransfer();
-              dt.setData('text/plain', ${JSON.stringify(content)});
-              const pasteEvent = new ClipboardEvent('paste', { clipboardData: dt, bubbles: true, cancelable: true });
-              editor.dispatchEvent(pasteEvent);
-              await new Promise(r => setTimeout(r, 500));
-              if (!editor.textContent || editor.textContent.trim().length === 0) {
-                editor.textContent = ${JSON.stringify(content)};
-                editor.dispatchEvent(new InputEvent('input', { bubbles: true, inputType: 'insertText', data: ${JSON.stringify(content)} }));
-              }
-            })()
-          `);
-          await delay(1500);
-          await win.webContents.executeJavaScript(`
-            (() => {
-              const btn = document.querySelector('[data-testid="tweetButton"], [data-testid="tweetButtonInline"]');
-              if (btn && !btn.disabled) btn.click();
-            })()
-          `);
-          await delay(3000);
-        } else if (platform === "linkedin") {
-          await win.webContents.executeJavaScript(`
-            (() => {
-              const btn = document.querySelector('button.share-box-feed-entry__trigger, button.artdeco-button--muted');
-              if (btn) btn.click();
-            })()
-          `);
-          await delay(2000);
-          await win.webContents.executeJavaScript(`
-            (async () => {
-              const editor = document.querySelector('[role="textbox"][contenteditable="true"], .ql-editor[contenteditable="true"]');
-              if (editor) {
-                editor.focus();
-                const dt = new DataTransfer();
-                dt.setData('text/plain', ${JSON.stringify(content)});
-                const pasteEvent = new ClipboardEvent('paste', { clipboardData: dt, bubbles: true, cancelable: true });
-                editor.dispatchEvent(pasteEvent);
-                await new Promise(r => setTimeout(r, 500));
-                if (!editor.textContent || editor.textContent.trim().length === 0) {
-                  editor.textContent = ${JSON.stringify(content)};
-                  editor.dispatchEvent(new InputEvent('input', { bubbles: true }));
-                }
-              }
-            })()
-          `);
-          await delay(1500);
-          await win.webContents.executeJavaScript(`
-            (() => {
-              const btn = document.querySelector('button.share-actions__primary-action, button.artdeco-button--primary[type="submit"]');
-              if (btn && !btn.disabled) btn.click();
-            })()
-          `);
-          await delay(3000);
-        }
+        remember(await cdp.clickFirst(selectors.submit, "submit"));
+        await cdp.waitForText(selectors.feedItems, content);
         summary = `Posted to ${platform}: "${content.slice(0, 50)}..."`;
         break;
       }
 
       case "reply": {
+        const targetUrl = requirePayloadText(payload.targetUrl, "targetUrl");
+        const replyContent = requirePayloadText(payload.content, "content");
+        await loadActionUrl(win, platform, action.actionType, targetUrl);
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        remember(await cdp.focusAndType(selectors.replyEditor, replyContent, "reply_editor"));
         assertNotCancelled();
-        const targetUrl = String(payload.targetUrl || "");
-        assertAllowedUrl(platform, targetUrl, "reply");
-        const replyContent = String(payload.content || "");
-        await win.loadURL(targetUrl);
-        await waitForLoad(win);
-        await delay(2000);
-        assertNotCancelled();
-
-        await win.webContents.executeJavaScript(`
-          (async () => {
-            const editor = document.querySelector('[data-testid="tweetTextarea_0"], [role="textbox"][contenteditable="true"]');
-            if (editor) {
-              editor.focus();
-              const dt = new DataTransfer();
-              dt.setData('text/plain', ${JSON.stringify(replyContent)});
-              const pasteEvent = new ClipboardEvent('paste', { clipboardData: dt, bubbles: true, cancelable: true });
-              editor.dispatchEvent(pasteEvent);
-              await new Promise(r => setTimeout(r, 500));
-              if (!editor.textContent || editor.textContent.trim().length === 0) {
-                editor.textContent = ${JSON.stringify(replyContent)};
-                editor.dispatchEvent(new InputEvent('input', { bubbles: true, inputType: 'insertText', data: ${JSON.stringify(replyContent)} }));
-              }
-            }
-          })()
-        `);
-        await delay(1500);
-        await win.webContents.executeJavaScript(`
-          (() => {
-            const btn = document.querySelector('[data-testid="tweetButton"], [data-testid="tweetButtonInline"], button[type="submit"]');
-            if (btn && !btn.disabled) btn.click();
-          })()
-        `);
-        await delay(3000);
+        remember(await cdp.clickFirst(selectors.replySubmit, "reply_submit"));
+        await cdp.waitForText(selectors.feedItems, replyContent);
         summary = `Replied to ${targetUrl.slice(0, 50)}`;
         break;
       }
 
       case "like": {
-        assertNotCancelled();
-        const targetUrl = String(payload.targetUrl || "");
-        assertAllowedUrl(platform, targetUrl, "like");
-        await win.loadURL(targetUrl);
-        await waitForLoad(win);
-        await delay(2000);
-        assertNotCancelled();
-        await win.webContents.executeJavaScript(`
-          (() => {
-            const btn = document.querySelector('[data-testid="like"], button[aria-label*="Like"]');
-            if (btn) btn.click();
-          })()
-        `);
-        await delay(2000);
+        const targetUrl = requirePayloadText(payload.targetUrl, "targetUrl");
+        await loadActionUrl(win, platform, action.actionType, targetUrl);
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        remember(await cdp.clickFirst(selectors.likeButton, "like_button"));
+        await cdp.waitForFirst(selectors.likedButton, "liked_state", 5_000);
         summary = `Liked post at ${targetUrl.slice(0, 50)}`;
         break;
       }
 
       case "follow": {
-        assertNotCancelled();
         const targetUrl = String(payload.targetUrl || payload.profileUrl || "");
-        assertAllowedUrl(platform, targetUrl, "follow");
-        await win.loadURL(targetUrl);
-        await waitForLoad(win);
-        await delay(2000);
-        assertNotCancelled();
-        await win.webContents.executeJavaScript(`
-          (() => {
-            const btn = document.querySelector('[data-testid*="follow"], button[aria-label*="Follow"]');
-            if (btn && !btn.textContent.includes('Following')) btn.click();
-          })()
-        `);
-        await delay(2000);
+        if (!targetUrl) throw browserVerificationFailed(platform, action.actionType, "missing targetUrl/profileUrl");
+        await loadActionUrl(win, platform, action.actionType, targetUrl);
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        remember(await cdp.clickFirst(selectors.followButton, "follow_button"));
+        await cdp.waitForFirst(selectors.followingButton, "following_state", 5_000);
         summary = `Followed user at ${targetUrl.slice(0, 50)}`;
         break;
       }
 
       case "browse_feed": {
-        assertNotCancelled();
         const feedUrl = String(payload.url || getFeedUrl(platform));
-        assertAllowedUrl(platform, feedUrl, "browse_feed");
         const maxPosts = Number(payload.maxPosts || 10);
-        await win.loadURL(feedUrl);
-        await waitForLoad(win);
-        await delay(3000);
-        assertNotCancelled();
-
-        for (let i = 0; i < 3; i++) {
-          await win.webContents.executeJavaScript("window.scrollBy(0, window.innerHeight)");
-          await delay(1500);
+        await loadActionUrl(win, platform, action.actionType, feedUrl);
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        for (let i = 0; i < 3; i += 1) {
+          await cdp.evaluate<void>("window.scrollBy(0, window.innerHeight)");
         }
-
-        const posts: string[] = await win.webContents.executeJavaScript(`
-          (() => {
-            const articles = document.querySelectorAll('article, [data-testid="tweet"], .feed-shared-update-v2');
-            return Array.from(articles).slice(0, ${maxPosts}).map(el => el.innerText.slice(0, 300));
-          })()
-        `);
-        summary = `Browsed feed — found ${posts.length} posts`;
+        const posts = await cdp.waitForAnyText(selectors.feedItems);
+        summary = `Browsed feed — found ${Math.min(posts.length, maxPosts)} posts`;
         break;
       }
 
       case "search": {
-        assertNotCancelled();
-        const query = String(payload.query || "");
-        const searchUrl = getSearchUrl(platform, query);
-        assertAllowedUrl(platform, searchUrl, "search");
-        await win.loadURL(searchUrl);
-        await waitForLoad(win);
-        await delay(3000);
-        assertNotCancelled();
-
-        const results: string[] = await win.webContents.executeJavaScript(`
-          (() => {
-            const items = document.querySelectorAll('article, [data-testid="tweet"], .search-result');
-            return Array.from(items).slice(0, 10).map(el => el.innerText.slice(0, 200));
-          })()
-        `);
+        const query = requirePayloadText(payload.query, "query");
+        await loadActionUrl(win, platform, action.actionType, getSearchUrl(platform, query));
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        const results = await cdp.waitForAnyText(selectors.searchItems);
         summary = `Search "${query.slice(0, 30)}" — ${results.length} results`;
         break;
       }
 
       case "screenshot": {
-        assertNotCancelled();
-        const url = String(payload.url || "about:blank");
-        if (url !== "about:blank") {
-          assertAllowedUrl(platform, url, "screenshot");
-          await win.loadURL(url);
-          await waitForLoad(win);
-          await delay(2000);
-        }
-        assertNotCancelled();
-        const title = await win.webContents.executeJavaScript("document.title");
+        const url = String(payload.url || getFeedUrl(platform));
+        await loadActionUrl(win, platform, action.actionType, url);
+        remember(await confirmAuthenticatedPage(win, cdp, selectors, platform, action.actionType));
+        const title = await cdp.evaluate<string>("document.title");
         summary = `Screenshot captured: ${title}`;
         break;
       }
@@ -289,18 +225,18 @@ export async function runAction(
         throw new Error(`Unsupported browser action type: ${action.actionType}`);
     }
 
-    try {
-      const image: NativeImage = await win.webContents.capturePage();
-      if (!image.isEmpty()) {
-        writeFileSync(screenshotPath, image.toPNG());
-      }
-    } catch (err) {
-      log.warn(`[browser] Screenshot failed: ${err}`);
-    }
-
-    await delay(1000);
-    if (!win.isDestroyed()) win.close();
-
+    assertNotCancelled();
+    await captureScreenshot(win, screenshotPath, action.id, "success");
+    await closeWindow(win);
+    logActionTelemetry({
+      platform,
+      action_type: action.actionType,
+      selector_hit: selectorHits.at(-1) ?? null,
+      selector_hits: selectorHits,
+      retries: cdp.getRetryCount(),
+      duration_ms: Date.now() - startedAt,
+      final_outcome: "success",
+    });
     return {
       success: true,
       cancelled: false,
@@ -309,22 +245,25 @@ export async function runAction(
       error: null,
     };
   } catch (error) {
-    const wasCancelled = cancelledActionIds.has(action.id) || (error instanceof Error && error.message === "BROWSER_ACTION_CANCELLED");
-    try {
-      const image: NativeImage = await win.webContents.capturePage();
-      if (!image.isEmpty()) writeFileSync(screenshotPath, image.toPNG());
-    } catch (screenshotError) {
-      log.warn(
-        `[browser] failure screenshot capture failed for action ${action.id}: ${screenshotError instanceof Error ? screenshotError.message : String(screenshotError)}`,
-      );
-    }
+    const wasCancelled = cancelledActionIds.has(action.id)
+      || (error instanceof Error && error.message === "BROWSER_ACTION_CANCELLED");
+    await captureScreenshot(win, screenshotPath, action.id, "failure");
+    await closeWindow(win);
 
-    if (!win.isDestroyed()) win.close();
-
-    const msg = wasCancelled ? "Action cancelled." : error instanceof Error ? error.message : String(error);
+    const msg = wasCancelled ? "Action cancelled." : describeBrowserActionError(error);
+    const finalOutcome = classifyBrowserOutcome(error, wasCancelled);
     if (!wasCancelled) {
       log.error(`[browser] Action ${action.actionType} failed: ${msg}`);
     }
+    logActionTelemetry({
+      platform,
+      action_type: action.actionType,
+      selector_hit: selectorHits.at(-1) ?? null,
+      selector_hits: selectorHits,
+      retries: cdp.getRetryCount(),
+      duration_ms: Date.now() - startedAt,
+      final_outcome: finalOutcome,
+    });
     return {
       success: false,
       cancelled: wasCancelled,
@@ -333,7 +272,83 @@ export async function runAction(
       error: msg,
     };
   } finally {
+    await cdp.dispose().catch(() => undefined);
     activeActionWindows.delete(action.id);
     cancelledActionIds.delete(action.id);
   }
 }
+
+async function confirmAuthenticatedPage(
+  win: BrowserWindow,
+  cdp: BrowserCdpClient,
+  selectors: PlatformSelectors,
+  platform: string,
+  actionType: string,
+): Promise<string> {
+  await assertAuthenticatedPage(() => win.webContents.getURL(), platform, actionType);
+  return cdp.waitForAuthenticatedSurface(
+    selectors.authenticated,
+    getPlatformRules(platform).authenticatedCookieNames,
+  );
+}
+
+async function loadActionUrl(
+  win: BrowserWindow,
+  platform: string,
+  actionType: string,
+  url: string,
+): Promise<void> {
+  assertAllowedUrl(platform, url, actionType);
+  await win.loadURL(url);
+  await waitForLoad(win, 15000, { platform, actionType });
+}
+
+function requirePayloadText(value: unknown, key: string): string {
+  const text = typeof value === "string" ? value.trim() : "";
+  if (text.length === 0) {
+    throw new Error(`Browser action payload missing ${key}.`);
+  }
+  return text;
+}
+
+async function captureScreenshot(
+  win: BrowserWindow,
+  screenshotPath: string,
+  actionId: string,
+  phase: "success" | "failure",
+): Promise<void> {
+  try {
+    const image: NativeImage = await win.webContents.capturePage();
+    if (!image.isEmpty()) {
+      writeFileSync(screenshotPath, image.toPNG());
+    }
+  } catch (err) {
+    log.warn(`[browser] ${phase} screenshot failed for action ${actionId}: ${err instanceof Error ? err.message : String(err)}`);
+  }
+}
+
+async function closeWindow(win: BrowserWindow): Promise<void> {
+  if (win.isDestroyed()) return;
+  await delay(250);
+  if (!win.isDestroyed()) win.close();
+}
+
+function describeBrowserActionError(error: unknown): string {
+  if (isAppError(error)) return `[${error.code}] ${error.message}`;
+  return error instanceof Error ? error.message : String(error);
+}
+
+function classifyBrowserOutcome(error: unknown, wasCancelled: boolean): BrowserActionOutcome {
+  if (wasCancelled) return "cancelled";
+  if (isAppError(error)) {
+    if (error.code === "browser.not_logged_in") return "logged_out";
+    if (error.code === "browser.selector_drift") return "selector_drift";
+    if (error.code === "browser.verification_failed") return "verification_failed";
+  }
+  if (error instanceof Error && /429|rate[_ -]?limit|too many requests/i.test(error.message)) return "rate_limited";
+  return "network";
+}
+
+function logActionTelemetry(telemetry: BrowserActionTelemetry): void {
+  log.info("[browser] action telemetry", telemetry);
+}
diff --git a/src/main/browser/browser-types.ts b/src/main/browser/browser-types.ts
index 2f620e15..233ab0a0 100644
--- a/src/main/browser/browser-types.ts
+++ b/src/main/browser/browser-types.ts
@@ -25,6 +25,7 @@ export interface PlatformRule {
   authCheckUrl: string;
   allowedHosts: string[];
   cookieOrigins: string[];
+  authenticatedCookieNames?: string[];
   unauthenticatedUrlMarkers: string[];
 }
 
@@ -34,6 +35,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://x.com/home",
     allowedHosts: ["x.com", "twitter.com"],
     cookieOrigins: ["https://x.com", "https://twitter.com"],
+    authenticatedCookieNames: ["auth_token"],
     unauthenticatedUrlMarkers: ["/i/flow/login", "/login"],
   },
   linkedin: {
@@ -41,6 +43,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.linkedin.com/feed/",
     allowedHosts: ["linkedin.com"],
     cookieOrigins: ["https://www.linkedin.com"],
+    authenticatedCookieNames: ["li_at"],
     unauthenticatedUrlMarkers: ["/login", "/checkpoint"],
   },
   instagram: {
@@ -48,6 +51,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.instagram.com/",
     allowedHosts: ["instagram.com"],
     cookieOrigins: ["https://www.instagram.com"],
+    authenticatedCookieNames: ["sessionid", "ds_user_id"],
     unauthenticatedUrlMarkers: ["/accounts/login"],
   },
   facebook: {
@@ -55,6 +59,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.facebook.com/",
     allowedHosts: ["facebook.com"],
     cookieOrigins: ["https://www.facebook.com"],
+    authenticatedCookieNames: ["c_user", "xs"],
     unauthenticatedUrlMarkers: ["/login"],
   },
   reddit: {
@@ -62,6 +67,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.reddit.com/",
     allowedHosts: ["reddit.com"],
     cookieOrigins: ["https://www.reddit.com"],
+    authenticatedCookieNames: ["reddit_session", "token_v2"],
     unauthenticatedUrlMarkers: ["/login"],
   },
   youtube: {
@@ -69,6 +75,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.youtube.com/",
     allowedHosts: ["youtube.com", "google.com"],
     cookieOrigins: ["https://www.youtube.com", "https://accounts.google.com"],
+    authenticatedCookieNames: ["SAPISID", "LOGIN_INFO"],
     unauthenticatedUrlMarkers: ["/signin", "/ServiceLogin"],
   },
   tiktok: {
@@ -76,6 +83,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.tiktok.com/foryou",
     allowedHosts: ["tiktok.com"],
     cookieOrigins: ["https://www.tiktok.com"],
+    authenticatedCookieNames: ["sessionid", "sessionid_ss"],
     unauthenticatedUrlMarkers: ["/login"],
   },
   bluesky: {
@@ -97,6 +105,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.threads.net/",
     allowedHosts: ["threads.net"],
     cookieOrigins: ["https://www.threads.net"],
+    authenticatedCookieNames: ["sessionid", "ds_user_id"],
     unauthenticatedUrlMarkers: ["/login"],
   },
   pinterest: {
@@ -104,6 +113,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://www.pinterest.com/",
     allowedHosts: ["pinterest.com"],
     cookieOrigins: ["https://www.pinterest.com"],
+    authenticatedCookieNames: ["_pinterest_sess"],
     unauthenticatedUrlMarkers: ["/login"],
   },
   telegram: {
@@ -132,6 +142,7 @@ export const PLATFORM_RULES: Record<string, PlatformRule> = {
     authCheckUrl: "https://weibo.com/",
     allowedHosts: ["weibo.com", "weibo.cn"],
     cookieOrigins: ["https://weibo.com"],
+    authenticatedCookieNames: ["SUB", "SUBP"],
     unauthenticatedUrlMarkers: ["/login", "/signup"],
   },
   xiaohongshu: {
diff --git a/src/main/browser/platform-selectors.ts b/src/main/browser/platform-selectors.ts
new file mode 100644
index 00000000..4c5a4207
--- /dev/null
+++ b/src/main/browser/platform-selectors.ts
@@ -0,0 +1,135 @@
+export interface PlatformSelectors {
+  authenticated: readonly string[];
+  composerOpen: readonly string[];
+  editor: readonly string[];
+  submit: readonly string[];
+  replyEditor: readonly string[];
+  replySubmit: readonly string[];
+  likeButton: readonly string[];
+  likedButton: readonly string[];
+  followButton: readonly string[];
+  followingButton: readonly string[];
+  feedItems: readonly string[];
+  searchItems: readonly string[];
+}
+
+const GENERIC_SELECTORS: PlatformSelectors = {
+  authenticated: [
+    "[data-testid='AppTabBar_Profile_Link']",
+    "a[href*='/in/']",
+    "img[alt*='profile' i]",
+    "[aria-label*='profile' i]",
+  ],
+  composerOpen: [
+    "button[aria-label*='post' i]",
+    "button[aria-label*='compose' i]",
+    "button.share-box-feed-entry__trigger",
+  ],
+  editor: [
+    "[role='textbox'][contenteditable='true']",
+    "textarea",
+    ".ql-editor[contenteditable='true']",
+  ],
+  submit: [
+    "button[type='submit']",
+    "button[aria-label*='post' i]",
+    "button[aria-label*='send' i]",
+  ],
+  replyEditor: [
+    "[role='textbox'][contenteditable='true']",
+    "textarea",
+  ],
+  replySubmit: [
+    "button[type='submit']",
+    "button[aria-label*='reply' i]",
+    "button[aria-label*='send' i]",
+  ],
+  likeButton: [
+    "button[aria-label*='like' i]",
+    "[role='button'][aria-label*='like' i]",
+  ],
+  likedButton: [
+    "button[aria-pressed='true'][aria-label*='like' i]",
+    "[data-testid='unlike']",
+  ],
+  followButton: [
+    "button[aria-label*='follow' i]",
+    "[role='button'][aria-label*='follow' i]",
+  ],
+  followingButton: [
+    "button[aria-label*='following' i]",
+    "button[aria-label*='requested' i]",
+  ],
+  feedItems: ["article", "[role='article']", ".feed-shared-update-v2"],
+  searchItems: ["article", "[role='article']", ".search-result", ".feed-shared-update-v2"],
+};
+
+const PLATFORM_SELECTORS: Record<string, Partial<PlatformSelectors>> = {
+  twitter: {
+    authenticated: [
+      "[data-testid='AppTabBar_Profile_Link']",
+      "[data-testid='SideNav_AccountSwitcher_Button']",
+      "a[aria-label*='Profile']",
+    ],
+    editor: [
+      "[data-testid='tweetTextarea_0']",
+      "[role='textbox'][contenteditable='true']",
+    ],
+    submit: [
+      "[data-testid='tweetButton']",
+      "[data-testid='tweetButtonInline']",
+    ],
+    replyEditor: [
+      "[data-testid='tweetTextarea_0']",
+      "[role='textbox'][contenteditable='true']",
+    ],
+    replySubmit: [
+      "[data-testid='tweetButton']",
+      "[data-testid='tweetButtonInline']",
+      "button[type='submit']",
+    ],
+    likeButton: ["[data-testid='like']", "button[aria-label*='Like']"],
+    likedButton: ["[data-testid='unlike']", "button[aria-label*='Unlike']"],
+    feedItems: ["article", "[data-testid='tweet']"],
+    searchItems: ["article", "[data-testid='tweet']"],
+  },
+  linkedin: {
+    authenticated: [
+      "a[href*='/in/']",
+      "img.global-nav__me-photo",
+      "button.global-nav__primary-link-me-menu-trigger",
+    ],
+    composerOpen: [
+      "button.share-box-feed-entry__trigger",
+      "button.artdeco-button--muted",
+    ],
+    editor: [
+      "[role='textbox'][contenteditable='true']",
+      ".ql-editor[contenteditable='true']",
+    ],
+    submit: [
+      "button.share-actions__primary-action",
+      "button.artdeco-button--primary[type='submit']",
+    ],
+    feedItems: [".feed-shared-update-v2", "article", ".update-components-text"],
+    searchItems: [".reusable-search__result-container", ".feed-shared-update-v2", "article"],
+  },
+};
+
+export function getPlatformSelectors(platform: string): PlatformSelectors {
+  const overrides = PLATFORM_SELECTORS[platform] ?? {};
+  return {
+    authenticated: overrides.authenticated ?? GENERIC_SELECTORS.authenticated,
+    composerOpen: overrides.composerOpen ?? GENERIC_SELECTORS.composerOpen,
+    editor: overrides.editor ?? GENERIC_SELECTORS.editor,
+    submit: overrides.submit ?? GENERIC_SELECTORS.submit,
+    replyEditor: overrides.replyEditor ?? overrides.editor ?? GENERIC_SELECTORS.replyEditor,
+    replySubmit: overrides.replySubmit ?? overrides.submit ?? GENERIC_SELECTORS.replySubmit,
+    likeButton: overrides.likeButton ?? GENERIC_SELECTORS.likeButton,
+    likedButton: overrides.likedButton ?? GENERIC_SELECTORS.likedButton,
+    followButton: overrides.followButton ?? GENERIC_SELECTORS.followButton,
+    followingButton: overrides.followingButton ?? GENERIC_SELECTORS.followingButton,
+    feedItems: overrides.feedItems ?? GENERIC_SELECTORS.feedItems,
+    searchItems: overrides.searchItems ?? overrides.feedItems ?? GENERIC_SELECTORS.searchItems,
+  };
+}
diff --git a/tests/unit/browser-action-runtime.test.ts b/tests/unit/browser-action-runtime.test.ts
new file mode 100644
index 00000000..c9904a08
--- /dev/null
+++ b/tests/unit/browser-action-runtime.test.ts
@@ -0,0 +1,65 @@
+import type { Session } from "electron";
+import { describe, expect, it } from "vitest";
+import {
+  assertAuthenticatedPage,
+  assertAuthenticatedSession,
+} from "../../src/main/browser/browser-action-auth";
+import { getPlatformSelectors } from "../../src/main/browser/platform-selectors";
+
+function fakeSession(cookiesByOrigin: Record<string, unknown[]>): Pick<Session, "cookies"> {
+  return {
+    cookies: {
+      get: async ({ url }) => cookiesByOrigin[url ?? ""] ?? [],
+    },
+  } as Pick<Session, "cookies">;
+}
+
+describe("browser action runtime guards", () => {
+  it("fails social actions before execution when the account session has no cookies", async () => {
+    await expect(
+      assertAuthenticatedSession(fakeSession({}), "twitter", "post"),
+    ).rejects.toMatchObject({
+      code: "browser.not_logged_in",
+    });
+  });
+
+  it("rejects guest cookies for platforms with explicit auth cookies", async () => {
+    await expect(
+      assertAuthenticatedSession(
+        fakeSession({ "https://x.com": [{ name: "guest_id", value: "present" }] }),
+        "twitter",
+        "post",
+      ),
+    ).rejects.toMatchObject({
+      code: "browser.not_logged_in",
+    });
+  });
+
+  it("accepts a persisted platform cookie before executing actions", async () => {
+    await expect(
+      assertAuthenticatedSession(
+        fakeSession({ "https://x.com": [{ name: "auth_token", value: "present" }] }),
+        "twitter",
+        "post",
+      ),
+    ).resolves.toBeUndefined();
+  });
+
+  it("treats login redirects as an unauthenticated page state", async () => {
+    await expect(
+      assertAuthenticatedPage(() => "https://x.com/i/flow/login", "twitter", "post"),
+    ).rejects.toMatchObject({
+      code: "browser.not_logged_in",
+    });
+  });
+
+  it("keeps platform selectors versioned outside the executor", () => {
+    const twitter = getPlatformSelectors("twitter");
+    const linkedin = getPlatformSelectors("linkedin");
+
+    expect(twitter.editor).toContain("[data-testid='tweetTextarea_0']");
+    expect(twitter.submit).toContain("[data-testid='tweetButton']");
+    expect(linkedin.composerOpen).toContain("button.share-box-feed-entry__trigger");
+    expect(linkedin.editor).toContain(".ql-editor[contenteditable='true']");
+  });
+});