diff --git a/README.md b/README.md
index 1d063d0..873acf3 100644
--- a/README.md
+++ b/README.md
@@ -481,7 +481,7 @@ Bundled scenarios under `apps/pearcord/scenarios/`:
 
 `mesh.connectGuildMeshThread(scenarioPath)` — optional `markThreadAndParentRead: true` in scenario JSON (v0.8.279). host steps + invite + `create-thread` + reply; guest must receive `threadReply` token.
 
-Scenario step extras (headless + attached `run`): `joinFirstVoice`, `joinFirstStage`, `stageFixtureSticker`, `sendMessageWithStagedStickers`, `openDmPeer`, `selectFirstForumChannel`, `selectSecondForumChannel`, `selectFirstTextChannel`, `selectSecondTextChannel`, `selectChannelNamed`, `selectChannelOtherThanActive`, `selectParentOfActiveThread`, `selectActiveThread`, `threadName` with `selectActiveThread`, `markActiveChannelRead`, `seedInboxNotification`, `markLatestNotificationRead`, `openLatestNotification`, `seedMentionAlertForActiveChannel`, `createThreadFromLastMessage`, `markThreadAndParentRead`, `toggleReactionOnLastMessage` (emoji string or `{ emoji }`), `stageFixtureAttachment` (`{ image: true }` for PNG), `sendMessageWithStagedAttachments`, `requestPreviewForStagedAttachment`, `messagesMin`, `messageContentIncludes`, `searchResultsMin`, `searchResultsMax`, `searchResultsCached`, `searchUnchanged`, `searchRecentIncludes`, `mentionAlertCountMax`, `notificationUnreadMin`, `notificationUnreadMax`, `reactionCountMin`, `reactionsInclude`, `attachmentsOnLastMessageMin`, `stickersOnLastMessageMin`, `activeChannelName`, `parentChannelPermissions` on `wait`. `waitEvent` supports `payloadType` (e.g. `attachment-preview`).
+Scenario step extras (headless + attached `run`): `joinFirstVoice`, `joinFirstStage`, `stageFixtureSticker`, `sendMessageWithStagedStickers`, `openDmPeer`, `selectFirstForumChannel`, `selectSecondForumChannel`, `selectFirstTextChannel`, `selectSecondTextChannel`, `selectChannelNamed`, `selectChannelOtherThanActive`, `selectParentOfActiveThread`, `selectActiveThread`, `threadName` with `selectActiveThread`, `markActiveChannelRead`, `seedInboxNotification`, `markLatestNotificationRead`, `openLatestNotification`, `seedMentionAlertForActiveChannel`, `createThreadFromLastMessage`, `markThreadAndParentRead`, `toggleReactionOnLastMessage` (emoji string or `{ emoji }`), `stageFixtureAttachment` (`{ image: true }` for PNG), `sendMessageWithStagedAttachments`, `requestPreviewForStagedAttachment`, `messagesMin`, `messageContentIncludes`, `searchResultsMin`, `searchResultsMax`, `searchResultsCached`, `searchUnchanged`, `searchRecentIncludes`, `mentionAlertCountMax`, `notificationUnreadMin`, `notificationUnreadMax`, `reactionCountMin`, `reactionsInclude`, `attachmentsOnLastMessageMin`, `stickersOnLastMessageMin`, `activeChannelName`, `parentChannelPermissions` on `wait`, and `waitLogContains` (`messageIncludes`/`contains` and optional `regex`/`lines`) for structured log verification. `waitEvent` supports `payloadType` (e.g. `attachment-preview`).
 
 ## Dependencies
 
diff --git a/headless.js b/headless.js
index df44b50..1023956 100644
--- a/headless.js
+++ b/headless.js
@@ -112,6 +112,66 @@ class HeadlessSession {
     throw new Error(`headless wait timeout: ${JSON.stringify(match)}`)
   }
 
+  _tailLogLines (lines = 200) {
+    const cap = Math.min(Math.max(1, Number(lines) || 200), 1000)
+    const logPath = path.join(this.storagePath, 'pearcord.log')
+    let text = ''
+    try {
+      text = fs.readFileSync(logPath, 'utf8')
+    } catch {
+      return { logPath, lines: [] }
+    }
+    return {
+      logPath,
+      lines: text.split('\n').filter(Boolean).slice(-cap)
+    }
+  }
+
+  async waitLogContains (spec, timeoutMs = 15000) {
+    const cfg =
+      typeof spec === 'string'
+        ? { messageIncludes: spec }
+        : spec && typeof spec === 'object'
+          ? spec
+          : {}
+    const messageIncludes = String(cfg.messageIncludes || cfg.contains || '').trim()
+    const regexSource = String(cfg.regex || '').trim()
+    const linesCap = Math.min(Math.max(1, Number(cfg.lines) || 300), 1000)
+    if (!messageIncludes && !regexSource) {
+      throw new Error('headless wait.logContains requires messageIncludes/contains or regex')
+    }
+    let regex = null
+    if (regexSource) {
+      try {
+        regex = new RegExp(regexSource)
+      } catch (err) {
+        throw new Error(`headless wait.logContains invalid regex: ${err?.message || String(err)}`)
+      }
+    }
+    const deadline = Date.now() + timeoutMs
+    let lastTail = []
+    let logPath = path.join(this.storagePath, 'pearcord.log')
+    while (Date.now() < deadline) {
+      const tail = this._tailLogLines(linesCap)
+      logPath = tail.logPath
+      lastTail = tail.lines
+      for (const line of lastTail) {
+        const includesOk = messageIncludes ? line.includes(messageIncludes) : true
+        const regexOk = regex ? regex.test(line) : true
+        if (includesOk && regexOk) return { line, logPath }
+      }
+      await new Promise((r) => setTimeout(r, 100))
+    }
+    throw new Error(
+      `headless wait.logContains timeout: ${JSON.stringify({
+        messageIncludes: messageIncludes || null,
+        regex: regexSource || null,
+        logPath,
+        inspectedLines: lastTail.length
+      })}`
+    )
+  }
+
   /**
    * @param {Array<{ ipc?: object, wait?: object, timeoutMs?: number }>} steps
    */
@@ -506,6 +566,10 @@ class HeadlessSession {
         }
         results.push({ waitEvent: step.waitEvent, payload: matched })
       }
+      if (step.waitLogContains) {
+        const matched = await this.waitLogContains(step.waitLogContains, step.timeoutMs)
+        results.push({ waitLogContains: step.waitLogContains, matched })
+      }
       if (step.createWebhookActiveChannel) {
         const spec =
           step.createWebhookActiveChannel && typeof step.createWebhookActiveChannel === 'object'
diff --git a/server.js b/server.js
index 74a00b4..1725c7d 100644
--- a/server.js
+++ b/server.js
@@ -153,6 +153,66 @@ class AgentServer {
     return req?.token === expected
   }
 
+  _logTailLines (lines = 200) {
+    const cap = Math.min(Math.max(1, Number(lines) || 200), 1000)
+    const logPath = resolveLogPath(this.storagePath)
+    let text = ''
+    try {
+      text = fs.readFileSync(logPath, 'utf8')
+    } catch {
+      return { logPath, lines: [] }
+    }
+    return {
+      logPath,
+      lines: text.split('\n').filter(Boolean).slice(-cap)
+    }
+  }
+
+  async _waitLogContains (spec, timeoutMs = 15000) {
+    const cfg =
+      typeof spec === 'string'
+        ? { messageIncludes: spec }
+        : spec && typeof spec === 'object'
+          ? spec
+          : {}
+    const messageIncludes = String(cfg.messageIncludes || cfg.contains || '').trim()
+    const regexSource = String(cfg.regex || '').trim()
+    const linesCap = Math.min(Math.max(1, Number(cfg.lines) || 300), 1000)
+    if (!messageIncludes && !regexSource) {
+      throw new Error('waitLogContains requires messageIncludes/contains or regex')
+    }
+    let regex = null
+    if (regexSource) {
+      try {
+        regex = new RegExp(regexSource)
+      } catch (err) {
+        throw new Error(`waitLogContains invalid regex: ${err?.message || String(err)}`)
+      }
+    }
+    const deadline = Date.now() + timeoutMs
+    let lastTail = []
+    let logPath = resolveLogPath(this.storagePath)
+    while (Date.now() < deadline) {
+      const tail = this._logTailLines(linesCap)
+      logPath = tail.logPath
+      lastTail = tail.lines
+      for (const line of lastTail) {
+        const includesOk = messageIncludes ? line.includes(messageIncludes) : true
+        const regexOk = regex ? regex.test(line) : true
+        if (includesOk && regexOk) return { line, logPath }
+      }
+      await sleep(100)
+    }
+    throw new Error(
+      `wait.logContains timeout: ${JSON.stringify({
+        messageIncludes: messageIncludes || null,
+        regex: regexSource || null,
+        logPath,
+        inspectedLines: lastTail.length
+      })}`
+    )
+  }
+
   async _runScenarioSteps (steps) {
     const results = []
     for (const step of steps || []) {
@@ -230,6 +290,11 @@ class AgentServer {
         }
         results.push({ waitEvent: step.waitEvent, event: matched })
       }
+      if (step.waitLogContains) {
+        const timeoutMs = Number(step.timeoutMs) || 15000
+        const matched = await this._waitLogContains(step.waitLogContains, timeoutMs)
+        results.push({ waitLogContains: step.waitLogContains, matched })
+      }
     }
     return results
   }
@@ -368,16 +433,8 @@ class AgentServer {
 
     if (req.op === 'log-tail') {
       const lines = Math.min(Number(req.lines) || 40, 500)
-      const logPath = resolveLogPath(this.storagePath)
-      let text = ''
-      try {
-        text = fs.readFileSync(logPath, 'utf8')
-      } catch {
-        this._reply(socket, { ...base, ok: true, lines: [], logPath })
-        return
-      }
-      const tail = text.split('\n').filter(Boolean).slice(-lines)
-      this._reply(socket, { ...base, ok: true, logPath, lines: tail })
+      const tail = this._logTailLines(lines)
+      this._reply(socket, { ...base, ok: true, logPath: tail.logPath, lines: tail.lines })
       return
     }