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Merged
pavelfeldman merged 1 commit into from
Jul 22, 2025
Merged

chore: move state to tab, do not cache snapshot #730

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7 changes: 0 additions & 7 deletions src/connection.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -60,13 +60,6 @@ export function createConnection(config: FullConfig, browserContextFactory: Brow
if (!tool)
return errorResult(`Tool "${request.params.name}" not found`);


const modalStates = context.modalStates().map(state => state.type);
if (tool.clearsModalState && !modalStates.includes(tool.clearsModalState))
return errorResult(`The tool "${request.params.name}" can only be used when there is related modal state present.`, ...context.modalStatesMarkdown());
if (!tool.clearsModalState && modalStates.length)
return errorResult(`Tool "${request.params.name}" does not handle the modal state.`, ...context.modalStatesMarkdown());

try {
return await context.run(tool, request.params.arguments);
} catch (error) {
Expand Down
168 changes: 13 additions & 155 deletions src/context.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -17,19 +17,12 @@
import debug from 'debug';
import * as playwright from 'playwright';

import { callOnPageNoTrace, waitForCompletion } from './tools/utils.js';
import { ManualPromise } from './manualPromise.js';
import { Tab } from './tab.js';
import { outputFile } from './config.js';

import type { ModalState, Tool, ToolActionResult } from './tools/tool.js';
import type { Tool } from './tools/tool.js';
import type { FullConfig } from './config.js';
import type { BrowserContextFactory } from './browserContextFactory.js';

type PendingAction = {
dialogShown: ManualPromise<void>;
};

const testDebug = debug('pw:mcp:test');

export class Context {
Expand All @@ -39,9 +32,6 @@ export class Context {
private _browserContextFactory: BrowserContextFactory;
private _tabs: Tab[] = [];
private _currentTab: Tab | undefined;
private _modalStates: (ModalState & { tab: Tab })[] = [];
private _pendingAction: PendingAction | undefined;
private _downloads: { download: playwright.Download, finished: boolean, outputFile: string }[] = [];
clientVersion: { name: string; version: string; } | undefined;

constructor(tools: Tool[], config: FullConfig, browserContextFactory: BrowserContextFactory) {
Expand All @@ -51,42 +41,13 @@ export class Context {
testDebug('create context');
}

clientSupportsImages(): boolean {
if (this.config.imageResponses === 'omit')
return false;
return true;
}

modalStates(): ModalState[] {
return this._modalStates;
}

setModalState(modalState: ModalState, inTab: Tab) {
this._modalStates.push({ ...modalState, tab: inTab });
}

clearModalState(modalState: ModalState) {
this._modalStates = this._modalStates.filter(state => state !== modalState);
}

modalStatesMarkdown(): string[] {
const result: string[] = ['### Modal state'];
if (this._modalStates.length === 0)
result.push('- There is no modal state present');
for (const state of this._modalStates) {
const tool = this.tools.find(tool => tool.clearsModalState === state.type);
result.push(`- [${state.description}]: can be handled by the "${tool?.schema.name}" tool`);
}
return result;
}

tabs(): Tab[] {
return this._tabs;
}

currentTabOrDie(): Tab {
if (!this._currentTab)
throw new Error('No current snapshot available. Capture a snapshot or navigate to a new location first.');
throw new Error('No open pages available. Use the "browser_navigate" tool to navigate to a page first.');
return this._currentTab;
}

Expand All @@ -109,9 +70,9 @@ export class Context {
return this._currentTab!;
}

async listTabsMarkdown(): Promise<string> {
async listTabsMarkdown(): Promise<string[]> {
if (!this._tabs.length)
return '### No tabs open';
return ['### No tabs open'];
const lines: string[] = ['### Open tabs'];
for (let i = 0; i < this._tabs.length; i++) {
const tab = this._tabs[i];
Expand All @@ -120,7 +81,7 @@ export class Context {
const current = tab === this._currentTab ? ' (current)' : '';
lines.push(`- ${i}:${current} [${title}] (${url})`);
}
return lines.join('\n');
return lines;
}

async closeTab(index: number | undefined) {
Expand All @@ -137,37 +98,17 @@ export class Context {
if (resultOverride)
return resultOverride;

if (!this._currentTab) {
return {
content: [{
type: 'text',
text: 'No open pages available. Use the "browser_navigate" tool to navigate to a page first.',
}],
};
}

const tab = this.currentTabOrDie();
// TODO: race against modal dialogs to resolve clicks.
const actionResult = await this._raceAgainstModalDialogs(async () => {
try {
if (waitForNetwork)
return await waitForCompletion(this, tab, async () => action?.()) ?? undefined;
else
return await action?.() ?? undefined;
} finally {
if (captureSnapshot && !this._javaScriptBlocked())
await tab.captureSnapshot();
}
});
const { actionResult, snapshot } = await tab.run(action || (() => Promise.resolve()), { waitForNetwork, captureSnapshot });

const result: string[] = [];
result.push(`### Ran Playwright code
\`\`\`js
${code.join('\n')}
\`\`\``);

if (this.modalStates().length) {
result.push('', ...this.modalStatesMarkdown());
if (tab.modalStates().length) {
result.push('', ...tab.modalStatesMarkdown());
return {
content: [{
type: 'text',
Expand All @@ -176,37 +117,13 @@ ${code.join('\n')}
};
}

const messages = tab.takeRecentConsoleMessages();
if (messages.length) {
result.push('', `### New console messages`);
for (const message of messages)
result.push(`- ${trim(message.toString(), 100)}`);
}

if (this._downloads.length) {
result.push('', '### Downloads');
for (const entry of this._downloads) {
if (entry.finished)
result.push(`- Downloaded file ${entry.download.suggestedFilename()} to ${entry.outputFile}`);
else
result.push(`- Downloading file ${entry.download.suggestedFilename()} ...`);
}
}
result.push(...tab.takeRecentConsoleMarkdown());
result.push(...tab.listDownloadsMarkdown());

if (captureSnapshot && tab.hasSnapshot()) {
if (snapshot) {
if (this.tabs().length > 1)
result.push('', await this.listTabsMarkdown());

if (this.tabs().length > 1)
result.push('', '### Current tab');
else
result.push('', '### Page state');

result.push(
`- Page URL: ${tab.page.url()}`,
`- Page Title: ${await tab.title()}`
);
result.push(tab.snapshotOrDie().text());
result.push('', ...(await this.listTabsMarkdown()));
result.push('', snapshot);
}

const content = actionResult?.content ?? [];
Expand All @@ -222,58 +139,6 @@ ${code.join('\n')}
};
}

async waitForTimeout(time: number) {
if (!this._currentTab || this._javaScriptBlocked()) {
await new Promise(f => setTimeout(f, time));
return;
}

await callOnPageNoTrace(this._currentTab.page, page => {
return page.evaluate(() => new Promise(f => setTimeout(f, 1000)));
});
}

private async _raceAgainstModalDialogs(action: () => Promise<ToolActionResult>): Promise<ToolActionResult> {
this._pendingAction = {
dialogShown: new ManualPromise(),
};

let result: ToolActionResult | undefined;
try {
await Promise.race([
action().then(r => result = r),
this._pendingAction.dialogShown,
]);
} finally {
this._pendingAction = undefined;
}
return result;
}

private _javaScriptBlocked(): boolean {
return this._modalStates.some(state => state.type === 'dialog');
}

dialogShown(tab: Tab, dialog: playwright.Dialog) {
this.setModalState({
type: 'dialog',
description: `"${dialog.type()}" dialog with message "${dialog.message()}"`,
dialog,
}, tab);
this._pendingAction?.dialogShown.resolve();
}

async downloadStarted(tab: Tab, download: playwright.Download) {
const entry = {
download,
finished: false,
outputFile: await outputFile(this.config, download.suggestedFilename())
};
this._downloads.push(entry);
await download.saveAs(entry.outputFile);
entry.finished = true;
}

private _onPageCreated(page: playwright.Page) {
const tab = new Tab(this, page, tab => this._onPageClosed(tab));
this._tabs.push(tab);
Expand All @@ -282,7 +147,6 @@ ${code.join('\n')}
}

private _onPageClosed(tab: Tab) {
this._modalStates = this._modalStates.filter(state => state.tab !== tab);
const index = this._tabs.indexOf(tab);
if (index === -1)
return;
Expand Down Expand Up @@ -353,9 +217,3 @@ ${code.join('\n')}
return result;
}
}

function trim(text: string, maxLength: number) {
if (text.length <= maxLength)
return text;
return text.slice(0, maxLength) + '...';
}
55 changes: 0 additions & 55 deletions src/pageSnapshot.ts
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