diff --git a/docs/src/api/class-page.md b/docs/src/api/class-page.md
index ae88787901030..5b11eace1c164 100644
--- a/docs/src/api/class-page.md
+++ b/docs/src/api/class-page.md
@@ -745,6 +745,11 @@ Maximum number of agentic turns to take per call. Defaults to 10.
 
 Secrets to hide from the LLM.
 
+### option: Page.agent.systemPrompt
+* since: v1.58
+- `systemPrompt` <[string]>
+
+System prompt for the agent's loop.
 
 ## async method: Page.bringToFront
 * since: v1.8
diff --git a/packages/playwright-client/types/types.d.ts b/packages/playwright-client/types/types.d.ts
index 1d0a59d40ea96..3e64513ef2bb0 100644
--- a/packages/playwright-client/types/types.d.ts
+++ b/packages/playwright-client/types/types.d.ts
@@ -2143,6 +2143,11 @@ export interface Page {
      * Secrets to hide from the LLM.
      */
     secrets?: { [key: string]: string; };
+
+    /**
+     * System prompt for the agent's loop.
+     */
+    systemPrompt?: string;
   }): Promise<PageAgent>;
 
   /**
diff --git a/packages/playwright-core/src/client/page.ts b/packages/playwright-core/src/client/page.ts
index 61cc51380e554..4f4c7b03559b2 100644
--- a/packages/playwright-core/src/client/page.ts
+++ b/packages/playwright-core/src/client/page.ts
@@ -858,6 +858,7 @@ export class Page extends ChannelOwner<channels.PageChannel> implements api.Page
       maxTokens: options.maxTokens,
       maxTurns: options.maxTurns,
       secrets: options.secrets ? Object.entries(options.secrets).map(([name, value]) => ({ name, value })) : undefined,
+      systemPrompt: options.systemPrompt,
     };
     const { agent } = await this._channel.agent(params);
     return PageAgent.from(agent);
diff --git a/packages/playwright-core/src/protocol/validator.ts b/packages/playwright-core/src/protocol/validator.ts
index 5481128be88dd..665e7a552b975 100644
--- a/packages/playwright-core/src/protocol/validator.ts
+++ b/packages/playwright-core/src/protocol/validator.ts
@@ -1491,12 +1491,13 @@ scheme.PageAgentParams = tObject({
   api: tOptional(tString),
   apiKey: tOptional(tString),
   apiEndpoint: tOptional(tString),
-  model: tOptional(tString),
   cacheFile: tOptional(tString),
   cacheOutFile: tOptional(tString),
-  secrets: tOptional(tArray(tType('NameValue'))),
   maxTurns: tOptional(tInt),
   maxTokens: tOptional(tInt),
+  model: tOptional(tString),
+  secrets: tOptional(tArray(tType('NameValue'))),
+  systemPrompt: tOptional(tString),
 });
 scheme.PageAgentResult = tObject({
   agent: tChannel(['PageAgent']),
diff --git a/packages/playwright-core/src/server/agent/pageAgent.ts b/packages/playwright-core/src/server/agent/pageAgent.ts
index d8fc98a5a94e1..91b595fbd6501 100644
--- a/packages/playwright-core/src/server/agent/pageAgent.ts
+++ b/packages/playwright-core/src/server/agent/pageAgent.ts
@@ -110,16 +110,26 @@ async function runLoop(progress: Progress, context: Context, toolDefinitions: To
     ...context.events,
   });
 
-  const task = `${userTask}
+  const task: string[] = [];
+  if (context.agentParams.systemPrompt) {
+    task.push('### System');
+    task.push(context.agentParams.systemPrompt);
+    task.push('');
+  }
 
-### Context history
-${context.history.map(h => `- ${h.type}: ${h.description}`).join('\n')}
+  task.push('### Task');
+  task.push(userTask);
 
-### Page snapshot
-${full}
-`;
+  if (context.history.length) {
+    task.push('### Context history');
+    task.push(context.history.map(h => `- ${h.type}: ${h.description}`).join('\n'));
+    task.push('');
+  }
+  task.push('### Page snapshot');
+  task.push(full);
+  task.push('');
+  await loop.run(task.join('\n'));
 
-  await loop.run(task);
   return { result: resultSchema ? reportedResult() : undefined };
 }
 
diff --git a/packages/playwright-core/types/types.d.ts b/packages/playwright-core/types/types.d.ts
index 1d0a59d40ea96..3e64513ef2bb0 100644
--- a/packages/playwright-core/types/types.d.ts
+++ b/packages/playwright-core/types/types.d.ts
@@ -2143,6 +2143,11 @@ export interface Page {
      * Secrets to hide from the LLM.
      */
     secrets?: { [key: string]: string; };
+
+    /**
+     * System prompt for the agent's loop.
+     */
+    systemPrompt?: string;
   }): Promise<PageAgent>;
 
   /**
diff --git a/packages/protocol/src/channels.d.ts b/packages/protocol/src/channels.d.ts
index bcf21f876f153..2f78521ef43b7 100644
--- a/packages/protocol/src/channels.d.ts
+++ b/packages/protocol/src/channels.d.ts
@@ -2586,23 +2586,25 @@ export type PageAgentParams = {
   api?: string,
   apiKey?: string,
   apiEndpoint?: string,
-  model?: string,
   cacheFile?: string,
   cacheOutFile?: string,
-  secrets?: NameValue[],
   maxTurns?: number,
   maxTokens?: number,
+  model?: string,
+  secrets?: NameValue[],
+  systemPrompt?: string,
 };
 export type PageAgentOptions = {
   api?: string,
   apiKey?: string,
   apiEndpoint?: string,
-  model?: string,
   cacheFile?: string,
   cacheOutFile?: string,
-  secrets?: NameValue[],
   maxTurns?: number,
   maxTokens?: number,
+  model?: string,
+  secrets?: NameValue[],
+  systemPrompt?: string,
 };
 export type PageAgentResult = {
   agent: PageAgentChannel,
diff --git a/packages/protocol/src/protocol.yml b/packages/protocol/src/protocol.yml
index 8dcf286b59703..1d603d65d80f6 100644
--- a/packages/protocol/src/protocol.yml
+++ b/packages/protocol/src/protocol.yml
@@ -2019,14 +2019,15 @@ Page:
         api: string?
         apiKey: string?
         apiEndpoint: string?
-        model: string?
         cacheFile: string?
         cacheOutFile: string?
+        maxTurns: int?
+        maxTokens: int?
+        model: string?
         secrets:
           type: array?
           items: NameValue
-        maxTurns: int?
-        maxTokens: int?
+        systemPrompt: string?
       returns:
         agent: PageAgent
 
diff --git a/tests/playwright-test/stable-test-runner/package-lock.json b/tests/playwright-test/stable-test-runner/package-lock.json
index 361b02fe0338c..5cd443046ac8b 100644
--- a/tests/playwright-test/stable-test-runner/package-lock.json
+++ b/tests/playwright-test/stable-test-runner/package-lock.json
@@ -5,16 +5,16 @@
   "packages": {
     "": {
       "dependencies": {
-        "@playwright/test": "^1.58.0-alpha-1767864918000"
+        "@playwright/test": "^1.58.0-alpha-2026-01-12"
       }
     },
     "node_modules/@playwright/test": {
-      "version": "1.58.0-alpha-1767864918000",
-      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.58.0-alpha-1767864918000.tgz",
-      "integrity": "sha512-MpTnHVq9cDe0awcG84SdCPx/oFcjs5U2sooSQHwJhKGisDaXnped2n+P4iFFRx6A33u13XQpsvNCEXAYa32Utg==",
+      "version": "1.58.0-alpha-2026-01-12",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.58.0-alpha-2026-01-12.tgz",
+      "integrity": "sha512-dU5+U3li4qVOpqk8kUebh+1pGI6YLwNJcD68HvRflYze9Q9hlGEZk6afb8IvdhprtrjfGchvZT3MsxuyfK/Lyw==",
       "license": "Apache-2.0",
       "dependencies": {
-        "playwright": "1.58.0-alpha-1767864918000"
+        "playwright": "1.58.0-alpha-2026-01-12"
       },
       "bin": {
         "playwright": "cli.js"
@@ -38,12 +38,12 @@
       }
     },
     "node_modules/playwright": {
-      "version": "1.58.0-alpha-1767864918000",
-      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.58.0-alpha-1767864918000.tgz",
-      "integrity": "sha512-l7e3/PeNy351d2rQrMqw1suOw4O+f5WyDIh08JX+w6UUNjZIwUjdYo/x5kViqJTNan2xsIVxM+v9U4pr2ABjGw==",
+      "version": "1.58.0-alpha-2026-01-12",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.58.0-alpha-2026-01-12.tgz",
+      "integrity": "sha512-qo6CQMIbyWScQBrI/ilgURc7DZoVr3Qd7LOKhlRqidzXLoTPWh9VQDjKxUdiZ6baRwxYfE7OwqVdVy0NB3dWjQ==",
       "license": "Apache-2.0",
       "dependencies": {
-        "playwright-core": "1.58.0-alpha-1767864918000"
+        "playwright-core": "1.58.0-alpha-2026-01-12"
       },
       "bin": {
         "playwright": "cli.js"
@@ -56,9 +56,9 @@
       }
     },
     "node_modules/playwright-core": {
-      "version": "1.58.0-alpha-1767864918000",
-      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.58.0-alpha-1767864918000.tgz",
-      "integrity": "sha512-KGg0syIJ6Vvt/ZpjIT/SD7T3eRRI9JO0k7wZR301F5qzaMbjJOWV5lpEjNG2dwfmPKr7rofmUkcFeWY29xTMLg==",
+      "version": "1.58.0-alpha-2026-01-12",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.58.0-alpha-2026-01-12.tgz",
+      "integrity": "sha512-XhRhPXOnA9TIMsIEtu9ooPcFDX1zMmWT4kCPknKrjYe1x8c8FbF/nqxxNjLMT7KA8VUFWfZrPXhSMhsRkuICmg==",
       "license": "Apache-2.0",
       "bin": {
         "playwright-core": "cli.js"
diff --git a/tests/playwright-test/stable-test-runner/package.json b/tests/playwright-test/stable-test-runner/package.json
index 74a7c34c070ab..686edf0159c80 100644
--- a/tests/playwright-test/stable-test-runner/package.json
+++ b/tests/playwright-test/stable-test-runner/package.json
@@ -1,6 +1,6 @@
 {
   "private": true,
   "dependencies": {
-    "@playwright/test": "^1.58.0-alpha-1767864918000"
+    "@playwright/test": "^1.58.0-alpha-2026-01-12"
   }
 }