Tommy D. Rossi
116 lines
2.9 KiB
Markdown
116 lines
2.9 KiB
Markdown
# Plan: Add Deterministic Page Waiting to mcp.ts
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## Current Problem
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In `mcp.ts`, both `connect()` and `reconnect()` functions:
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```typescript
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const browser = await chromium.connectOverCDP(cdpEndpoint)
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const context = contexts[0]
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const pages = context.pages() // May be empty!
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if (pages.length === 0) {
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throw new Error(NO_TABS_ERROR)
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}
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```
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This fails when:
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1. Extension has tabs connected, but...
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2. Playwright hasn't finished processing `Target.attachedToTarget` + `Runtime.executionContextCreated` events
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## Solution
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Use `context.waitForEvent('page')` with a timeout, similar to our test fix.
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## Implementation Plan
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### Step 1: Create a helper function
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```typescript
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async function waitForPages(context: BrowserContext, options?: {
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timeout?: number
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minPages?: number
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}): Promise<Page[]> {
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const { timeout = 5000, minPages = 1 } = options || {}
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// Check if pages already exist
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let pages = context.pages()
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if (pages.length >= minPages) {
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return pages
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}
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// Wait for page events
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const startTime = Date.now()
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while (pages.length < minPages && Date.now() - startTime < timeout) {
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try {
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await context.waitForEvent('page', { timeout: timeout - (Date.now() - startTime) })
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pages = context.pages()
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} catch {
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// Timeout - check one more time
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pages = context.pages()
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break
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}
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}
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return pages
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}
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```
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### Step 2: Update `connect()` function (line ~305)
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```typescript
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// Before:
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const pages = context.pages()
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if (pages.length === 0) {
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throw new Error(NO_TABS_ERROR)
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}
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// After:
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const pages = await waitForPages(context, { timeout: 5000 })
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if (pages.length === 0) {
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throw new Error(NO_TABS_ERROR)
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}
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```
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### Step 3: Update `reconnect()` function (line ~448)
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Same change as above.
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### Step 4: Consider the "createInitialTab" flow
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The relay server has a `createInitialTab` message for when no tabs exist. We should:
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1. First try `waitForPages()` with a short timeout (1-2 seconds)
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2. If still no pages, request `createInitialTab`
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3. Then `waitForPages()` again for the new tab
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```typescript
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let pages = await waitForPages(context, { timeout: 2000 })
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if (pages.length === 0) {
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// No tabs - request extension to create one
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await requestCreateInitialTab()
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pages = await waitForPages(context, { timeout: 5000 })
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}
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if (pages.length === 0) {
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throw new Error(NO_TABS_ERROR)
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}
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```
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## Testing
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1. Run existing tests to ensure no regression
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2. Add a new test that:
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- Connects immediately after extension toggle
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- Verifies pages are available without sleep
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## Files to Modify
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1. `playwriter/src/mcp.ts`:
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- Add `waitForPages()` helper
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- Update `connect()` function
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- Update `reconnect()` function
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## Edge Cases
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1. **All pages are `about:blank`**: May need to filter for real pages
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2. **Extension not connected**: Existing timeout handling should work
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3. **Very slow page load**: 5 second timeout should be sufficient for CDP events (actual page content load is not required)
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