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fix(pages): report the actual page size after resize_page (#2998) - #3132
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OrKoN
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Please address the following:
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src/tools/pages.ts(resizePage): verify the page's content size, not the window bounds.page.resize()takescontentWidth/contentHeight, whileBrowser.getWindowBounds()returns the outer window including tab strip and toolbar, so the two are only equal by accident (headless, no decorations); on headful or scaled displays the strict width comparison throws for a successful resize. Read the result withPage.getLayoutMetrics(cssLayoutViewport.clientWidth/clientHeight) orinnerWidth/innerHeightand compare both dimensions exactly to the request. -
src/tools/pages.ts(resizePage): make the height check symmetric with the width check. Chrome clamps up to its minimum size (the issue shows100x100→500x100headless and500x232headful), sonewBounds.height < request.params.heightnever fires for the reported bug; a request of800x100that ends at800x232still returns an unqualified success. -
src/tools/pages.ts(resizePage): move the comparison out of thetryblock and drop theerr.message.startsWith('Could not resize page')re-throw. Only the bounds lookup can fail on unsupported platforms; matching your own error by prefix to decide whether to swallow it is fragile and hides any other error from the lookup. -
Move the verification into
McpPage(for exampleMcpPage.resize()returning the resulting content size) and test it withcreateMockPuppeteerPage(), followingtests/McpPage.test.ts. The new real-browser test depends on Chrome's platform-specific minimum window size (100x100clamping), which differs between headless Linux CI and headful macOS/Windows, andAGENTS.mdasks tool tests to be mock-based.
Nits
- Consider reporting instead of throwing: append
Requested 100x100, page is 500x100to the response and still include the page list. The resize did take effect, and an agent gets more value from the actual size than from an error that hides it; either way, state the behavior in the tool description anddocs/tool-reference.md.
## Summary Add a **Pre-submit checklist** section to `AGENTS.md`. Each item comes from a recent review finding or a landed bug fix in this repository. The checklist has five groups: - **Scope and PR description**: one change per PR, title and commit type match, description lists every behavior change and matches the diff, `npm run gen` and `npm run format` ran. - **Design**: fix in the lowest layer that owns the data, fix upstream (Puppeteer, devtools-frontend) first, one helper for repeated code, options objects instead of positional `undefined` arguments, validation in Zod schemas. - **Correctness and edge cases**: no stale state after a failed call, artifacts written before a throw, abandoned async continuations, mutex guards, file removal races, `dispose()` releases every resource, secrets never reach logs, path parameters validated even when they parse as URLs. - **Tests**: every new function has a test, no vacuous assertions, `notCalled` targets the first call after validation, exact-argument assertions, reusable stubs in `tests/mocks.ts`, bounded timeouts, no second CDP session for event waits. - **Documentation and output**: tool descriptions state when a parameter is ignored, skills stay generic, one-sentence inline comments. Sources: review comments on ChromeDevTools#2679, ChromeDevTools#2797, ChromeDevTools#2859, ChromeDevTools#2881, ChromeDevTools#2901, ChromeDevTools#3048, ChromeDevTools#3082, ChromeDevTools#3109, ChromeDevTools#3120, ChromeDevTools#3132, ChromeDevTools#3134, ChromeDevTools#3139, ChromeDevTools#3148, ChromeDevTools#3156, ChromeDevTools#3158, ChromeDevTools#3161, ChromeDevTools#3182, ChromeDevTools#3183, ChromeDevTools#3186, ChromeDevTools#3187, ChromeDevTools#3188, ChromeDevTools#3189, ChromeDevTools#3192, ChromeDevTools#3196, ChromeDevTools#3197, ChromeDevTools#3198, ChromeDevTools#3203, ChromeDevTools#3204, and fixes ChromeDevTools#3150, ChromeDevTools#3160, ChromeDevTools#3185, ChromeDevTools#3202, ChromeDevTools#3207, ChromeDevTools#3208. Existing content in `AGENTS.md` is unchanged. Closes ChromeDevTools#3222
…verify-bounds # Conflicts: # tests/tools/pages.test.ts
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Moved Page.getLayoutMetrics into McpPage.resize, updated the warning format to "Requested ${width}x${height}, page is ${actual.width}x${actual.height}", and combined the clamping assertions into unit tests. |
…verify-bounds # Conflicts: # tests/McpPage.test.ts
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Thanks, please check the following:
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src/McpPage.ts(resize()): remove theif (!metrics?.cssLayoutViewport)guard and the| undefinedit produces, becauseProtocol.Page.GetLayoutMetricsResponse.cssLayoutViewportis a non-optional field andAGENTS.mdforbids optional chaining on non-optional values. The guard exists only because the default mocksendresolves{}; set the mock response in the test instead. -
tests/McpPage.test.ts(resize()): add a test for thegetDialog()branch that stubs an open dialog, assertscalledOnceWithExactly(pptrPage.resize, ...), assertscdpSession.sendis not called withPage.getLayoutMetrics, and asserts the result isundefined. The branch has no test, andtests/tools/pages.test.tshas no test for theactualSize === undefinedpath of the handler either. -
Update the PR title and body: the title says "verify applied window bounds" and the body says "report when window dimensions are clamped by the OS/window manager", but the diff reads the CSS layout viewport and appends the actual page size to the response. The squash commit message must describe the shipped behavior, for example
fix(pages): report the actual page size after resize_page (#2998).
Remove the cssLayoutViewport guard in McpPage.resize(). The field is not optional in Protocol.Page.GetLayoutMetricsResponse. Add a test for the open dialog branch of McpPage.resize(). Add a resize_page handler test for an unknown actual page size.
…verify-bounds # Conflicts: # src/tools/ToolDefinition.ts
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…evTools#3308) This reverts commit f003056 (ChromeDevTools#3132). `McpPage.resize()` read `Page.getLayoutMetrics` from the target page after the resize. Chrome does not lay out a background tab again until the tab is visible. Thus, for a background tab, `resize_page` reported the old page size (for example `Requested 1100x750, page is 1504x836`), although the window had the requested size. The window bounds (`Browser.getWindowBounds`) cannot replace the layout metrics. They give the outer window size, which includes the tab strip and the toolbar, not the page size. `resize_page` again prints no page size. ChromeDevTools#2998 is open again. Fixes ChromeDevTools#3306
🤖 I have created a release *beep* *boop* --- ## [1.12.0](chrome-devtools-mcp-v1.11.0...chrome-devtools-mcp-v1.12.0) (2026-10-22) ### 🎉 Features * add --maxNavigationSaved flag to configure retained navigation history ([#3018](#3018)) ([a580d13](a580d13)) * add Kimi Code plugin manifest ([#3029](#3029)) ([cd00b64](cd00b64)) * Analyze heap snapshots without a browser connection ([#3156](#3156)) ([78c8320](78c8320)) * **config:** add --watchConfig to reload config file changes ([#3248](#3248)) ([b48561f](b48561f)) * **config:** introduce layered ServerConfig for live reload ([#3203](#3203)) ([37f1fda](37f1fda)) * **config:** share ReadonlyServerConfig with McpContext and McpPage ([#3204](#3204)) ([0813bf3](0813bf3)) * **config:** support reloading blockedUrlPattern and allowedUrlPattern ([#3268](#3268)) ([cc850f5](cc850f5)) * **context:** release disabled feature state on config reload ([#3049](#3049)) ([c0140d1](c0140d1)) * Paginate by default in heap snapshot tools ([#3201](#3201)) ([fb8375b](fb8375b)) * Paginate detailed diff in compare_heapsnapshots ([#3195](#3195)) ([4a9dd53](4a9dd53)) * run independent tool calls in parallel with a TaskRunner ([#3243](#3243)) ([8a8d877](8a8d877)) * run page-scoped tools on different pages in parallel ([#3252](#3252)) ([f8f18ac](f8f18ac)) * **server:** add McpServer.applyConfig() to reload configuration ([#3051](#3051)) ([f874aeb](f874aeb)) * **slim:** support filepath in slim mode screenshot ([#3296](#3296)) ([d399c4a](d399c4a)) * Sort objects for class by self size in compare_heapsnapshots ([#3205](#3205)) ([f8a18c6](f8a18c6)) * **tools:** support updating ToolHandler definitions in place ([#3050](#3050)) ([8064138](8064138)) * **wait_for:** support opt-in visible text matching ([#3212](#3212)) ([eef92da](eef92da)) ### 🛠️ Fixes * allow paths below a filesystem-root workspace root ([#3277](#3277)) ([296ccef](296ccef)) * block evaluate_script while a dialog is open ([#3196](#3196)) ([545bcbb](545bcbb)) * bound take_snapshot wait and clear the geolocation override ([#3265](#3265)) ([6282f54](6282f54)) * **browser:** redact WebSocket headers from connection logs ([#2901](#2901)) ([3a2f91e](3a2f91e)) * capture thrown transform errors as Zod validation issues ([#3242](#3242)) ([0f95c21](0f95c21)) * clear handled dialog in McpPage.getDialog() ([#3241](#3241)) ([2ab93a3](2ab93a3)), closes [#2958](#2958) * **cli:** disallow --slim in CLI start options ([#2987](#2987)) ([#3113](#3113)) ([ae3f61c](ae3f61c)) * **cli:** do not forward tool args to start ([#3114](#3114)) ([fef1598](fef1598)) * **cli:** serialize object daemon arguments ([#2797](#2797)) ([f73a440](f73a440)) * close the tab opened by a failed new_page ([#2928](#2928)) ([c174677](c174677)) * **config:** accept native JSON objects for wsHeaders in config files ([#3262](#3262)) ([371e6c2](371e6c2)) * **console:** describe Map, Set, function, DOM node, symbol and cyclic arguments ([#3199](#3199)) ([968e4e5](968e4e5)) * **console:** include the reason of unhandled promise rejections ([#3148](#3148)) ([f7cdf73](f7cdf73)) * defer focus emulation until a page is explicitly targeted ([#3230](#3230)) ([35abe35](35abe35)) * disable Puppeteer signal handlers for launched browsers ([#3238](#3238)) ([3afec73](3afec73)), closes [#3154](#3154) * discover third-party developer tools before tool lookup ([#3208](#3208)) ([2777fa0](2777fa0)), closes [#2973](#2973) * discover third-party developer tools in page tools ([#3207](#3207)) ([cf33529](cf33529)), closes [#2980](#2980) * drop InlineTextBox nodes from text snapshots ([#3202](#3202)) ([f8c775a](f8c775a)) * **emulate:** keep previous viewport when setViewport fails ([#3150](#3150)) ([19d883c](19d883c)) * exclude source maps from the npm package ([#3295](#3295)) ([d575da4](d575da4)) * keep surrogate pairs and emoji whole when truncating titles, names and bodies ([#3215](#3215)) ([058adcf](058adcf)) * let resourceTypes match CORS preflights and prefetches ([#3217](#3217)) ([e342c6e](e342c6e)) * **lighthouse:** explain unsupported URL schemes in navigation mode ([#3144](#3144)) ([c6ad84a](c6ad84a)) * **lighthouse:** fail the audit when Lighthouse reports a runtime error ([#3188](#3188)) ([53ea78d](53ea78d)) * **lighthouse:** restore the emulated viewport after a navigation audit ([#3189](#3189)) ([c777ece](c777ece)) * **network:** list only earlier hops in a request's redirect chain ([#3198](#3198)) ([4675940](4675940)) * **network:** remove unsupported websocket from list_network_requests filter ([#2961](#2961)) ([#3282](#3282)) ([8b119d9](8b119d9)) * **network:** reset page network emulation before applying URL restrictions ([#3312](#3312)) ([f25f3df](f25f3df)) * **pages:** reject devtools:// URLs in navigate_page and new_page ([#2935](#2935)) ([#3128](#3128)) ([c94c03d](c94c03d)) * **pages:** report the actual page size after resize_page ([#2998](#2998)) ([#3132](#3132)) ([f003056](f003056)) * **pages:** revert reporting the page size after resize_page ([#3308](#3308)) ([186ea66](186ea66)), closes [#3306](#3306) * **pagination:** return all items when pageSize is omitted and pageIdx is 0 ([#2996](#2996)) ([#3134](#3134)) ([3ad9115](3ad9115)) * **performance:** populate structuredContent for traceInsight in performance_analyze_insight ([#2981](#2981)) ([#3115](#3115)) ([c2c6cc4](c2c6cc4)) * preserve unread page fallback across snapshots and deduplicate page disposal ([#3161](#3161)) ([8604365](8604365)) * print the no-roots temp-directory warning under default flags ([#2927](#2927)) ([0dd8ed9](0dd8ed9)) * reject empty, extra, and unknown parts in geolocation and viewport transforms ([#3097](#3097)) ([#3120](#3120)) ([3ea31fb](3ea31fb)) * resolve error causes on the session that reported the exception ([#3220](#3220)) ([b2d37e8](b2d37e8)) * resolve service worker IDs for console messages ([#2881](#2881)) ([3804a9a](3804a9a)) * return message when page exposes no 3p developer tools ([#3197](#3197)) ([663f3c3](663f3c3)), closes [#3004](#3004) * **script:** surface non-Error thrown and rejected values in evaluate_script ([#2951](#2951)) ([#3127](#3127)) ([b1e6e68](b1e6e68)) * **security:** validate filesystem paths that parse as http/ws URLs ([#3186](#3186)) ([91e112d](91e112d)) * **snapshot:** omit uid for accessibility nodes without backendNodeId ([#3187](#3187)) ([9054351](9054351)) * stop active screencast on McpPage.dispose() ([#3160](#3160)) ([558af81](558af81)) * stop get_network_request waiting forever for an unread no-store body ([#3216](#3216)) ([c556be1](c556be1)) * surface nested error causes and autoConnect hint on connection failure ([#3111](#3111)) ([d7f1e78](d7f1e78)) * treat 0.0.0.0 and [::] browser endpoints as local ([#3321](#3321)) ([7d5f7de](7d5f7de)) * treat IPv4-mapped IPv6 loopback as localhost ([#3255](#3255)) ([6cfb34c](6cfb34c)) * truncate data: URLs in accessibility snapshots ([#3292](#3292)) ([11e7d47](11e7d47)) * validate type_text submitKey before typing ([#3185](#3185)) ([c8615d7](c8615d7)) * **wait_for:** find text in dynamically attached iframes ([#3210](#3210)) ([5f84888](5f84888)) * warn when screenshot dimensions exceed 16384px limit ([#2952](#2952)) ([#3291](#3291)) ([10455b7](10455b7)) ### 📄 Documentation * add a pre-submit checklist to AGENTS.md ([#3236](#3236)) ([e96ee6c](e96ee6c)) * clarify URL pattern port and hostname matching ([#3287](#3287)) ([4723335](4723335)) * **config:** note that hot-reloaded URL restrictions keep open targets attached ([#3314](#3314)) ([47db2b8](47db2b8)) * correct CLI availability of extension tools ([#2852](#2852)) ([a7280ee](a7280ee)) * explain how to install skills, including the CLI skill ([#3274](#3274)) ([46eb546](46eb546)) * remove experimental status from CLI and promote it in README ([#3273](#3273)) ([0ced16b](0ced16b)) * require a rebase only when the branch has merge conflicts ([#3239](#3239)) ([d1143ac](d1143ac)) * **skills:** clarify Lighthouse score scale and contrast workflow ([#3006](#3006)) ([#3218](#3218)) ([bf8c6d9](bf8c6d9)) ### ⚡ Performance * **cli:** load a small third-party bundle in the chrome-devtools CLI ([#3200](#3200)) ([552e1f8](552e1f8)) * load the Lighthouse bundle on first use ([#3169](#3169)) ([798f03a](798f03a)) ### 🏗️ Refactor * **config:** isolate scripts and unit tests from home config discovery ([#3256](#3256)) ([65e6b97](65e6b97)) * **config:** lock slim and pageIdRouting options when viaCli is set ([#3257](#3257)) ([384d9aa](384d9aa)) * **config:** pass ReadonlyServerConfig to BrowserManager and add OptionGate ([#3267](#3267)) ([98302f2](98302f2)) * **config:** simplify watchConfig and start watcher inside connect ([#3259](#3259)) ([878c5f6](878c5f6)) * extract errorResult() and routedPageId() in ToolHandler ([#3251](#3251)) ([9a6b03a](9a6b03a)) * import types and values from a module in one statement ([#3303](#3303)) ([f4eaf1f](f4eaf1f)) * **lighthouse:** move Lighthouse runner methods to McpPage and add bundle types ([#3283](#3283)) ([e1823a2](e1823a2)) * list optional properties last in inline object types ([#3302](#3302)) ([dc929c0](dc929c0)) * register all tools upfront across modes ([#3163](#3163)) ([58f8d1f](58f8d1f)) * **response:** pass live ReadonlyServerConfig to McpResponse ([#3258](#3258)) ([6042490](6042490)) * **tools:** add explicit factory types to tool definitions ([#3284](#3284)) ([4d1d7b2](4d1d7b2)) * use #private names instead of the private modifier ([#3301](#3301)) ([2e13311](2e13311)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).
After
resize_pageresizes the page, the tool reads the CSS layout viewport of the page (Page.getLayoutMetrics). If the actual page size is different from the requested size, the tool adds this line to the response:Requested <width>x<height>, page is <actualWidth>x<actualHeight>Changes:
resize_pagehandler toMcpPage.resize().McpPage.resize()returns the actual page size fromcssLayoutViewport.McpPage.resize()does not read the layout metrics and returnsundefined. The tool then adds no size line.resize_pagetool description.Fixes #2998