13.6.0 (2026-10-27)

Full Changelog

We expect this release to ship in the DevTools of Chrome 159, and to PageSpeed Insights within a week.

New contributors

Thanks to our new contributors 👽🐷🐰🐯🐻!

• Nikolay Vitkov @Lightning00Blade
• MohammadHossein Jahanbakhsh @MHJahanbakhsh
• Rafe Blandford @rafeblandford
• Roman @gameroman
• Ivan Akulov @iamakulov
• Francesco Marinoni Moretto @frmoretto

Notable Changes

• CLI bulk URL auditing: The CLI now supports auditing multiple URLs sequentially in a single command—either by passing multiple URL arguments or via --url-file (with --fail-fast to abort on the first failure) (#17404). Default report filenames now include the URL pathname (<hostname>-<pathname>_<date>) to avoid collisions across pages on the same host (#17405, #17423).
• Lantern simulation improvements: Upgraded trace_engine (0.0.66 and 0.0.67) and updated request/graph modeling to improve simulation accuracy (#17307, #17379):
  • Network & protocol modeling: Treated HTTP/3 connections as multiplexed, credited consumed H2 overflow bytes across simulation steps, excluded connectionless requests from active connection counts, and improved origin RTT/throughput estimation and redirect handling (#17415).
  • Dependency graph & metrics: Added v8.compileModule and v8.evaluateModule trace event attribution, used protocol renderBlocking status for render-blocking priority (#16869), used FCP graphs when text LCP occurs in the same frame as FCP, and fixed simulated LCP breakdown calculations (#17269) and trace-mode navigation/URL handling (#17431, #17433).
• Agentic Resource Discovery (ARD) v0.91: Updated the ard-schema audit and gatherer to the ARD v0.91 specification (ard.json replacing ai-catalog.json), supporting discovery via Link HTTP headers, <link rel="ard">, and /.well-known/ard.json, warning on legacy ai-catalog locations, and displaying the ARD spec version in the report footer (#17258, #17259, #17260, #17448, #17452).
• Performance insight numericValue: Performance insight audits now populate numericValue and numericUnit from estimated time or byte savings (#17346), and select the correct navigation when traces contain multiple navigations (#17174).
• Memory and gathering optimizations: Reduced peak memory usage during runs by streaming traces (ReturnAsStream), reusing script sources from trace events, evicting decoded frame buffers in speedline, and releasing intermediate gatherer and trace engine state (#17286, #17289, #17290, #17407).

Core

• fix cycle tracking and built-in type checks in deep-equals (#17422)
• release retained gatherer and trace engine intermediate state (#17290)
• populate numericValue on performance insight audits (#17346)
• do not throw when robots.txt or llms.txt content is null (#17294)
• fail robots-txt and llms-txt on HTTP 429 (#17295)
• fix insight audits picking the wrong navigation's data (#17174)
• ard: include ARD spec version in LHR credits and report footer (#17452)
• ard: sync port with upstream f073b1e (#17448)
• ard: make upstream sync check content-based (#17261)
• ard: report legacy and unreachable discovery sources (#17260)
• ard: discover manifests per spec §5.1 (#17259)
• ard: port conformance test to ARD v0.91 (#17258)
• baseline: link to developer.chrome.com docs (#17177)
• baseline: show baseline_low_date for Widely Available features (#17337)
• baseline: fix getLowDate for high features, move web-features to devDeps (#17283)
• cdt: convert core/lib/cdt to ESM (#17340)
• config: throw when module is missing from bundledModules in bundled env (#17398)
• driver: skip clearDataForOrigin when origin is null (#17347)
• full-page-screenshot: preserve emulated width during resize (#17330)
• image-elements: skip source rules when HTML dimensions are explicit (#17287)
• lantern-metric: use last main-frame navigation in trace mode (#17433)
• lcp-network-record: rename artifact, include Media requests (#17324)
• legacy-javascript: fix es-shims regex matching (#17421)
• legacy-javascript: update core-js data, detect newly baseline polyfills (#17304)
• legacy-javascript: optimize pattern matching and source map lookup (#17301)
• legacy-javascript: fix CRLF and multi-line line/column tracking (#17300)
• legacy-javascript: skip newly baseline features (#17299)
• minification-estimator: avoid per-character substring allocations (#17288)
• network-request: update Lightrider protocol, size, and timings on redirects (#17415)
• network-request: set renderBlocking from protocol (#16869)
• page-dependency-graph: strip #hash fragments from trace request URLs (#17431)
• page-functions: clone element into template document (#17273)
• predictive-perf: fix simulated LCP breakdown (#17269)
• robots-txt: add License directive (#17160)
• script-treemap-data: pass deduplicated scripts to module duplication (#17427)
• script-treemap-data: deduplicate scripts sharing a network record (#17382)
• scripts: remove leftover _scriptContents reset (#17377)
• scripts: reuse script sources from trace rundown events (#17289)
• speedline: evict decoded RGBA buffers from frame closures (#17286)
• trace: use ReturnAsStream transferMode for Tracing.start (#17407)
• unused-css: merge overlapping and duplicate rule usage ranges (#17412)

CLI

• follow symlinks when checking directory paths (#17416)
• support auditing multiple URLs in bulk (#17404)

Report

• validate image and screenshot URLs before rendering (#17446)
• add rel=noopener to target=_blank links (#17449)
• render performance diagnostics when insights group is missing (#17406)
• file-namer: truncate name in generated filename prefix (#17423)
• file-namer: include pathname in generated filename prefix (#17405)

Deps

• upgrade deps (#17445)
• remove csv-validator (#17399)
• replace conventional-changelog-cli with conventional-changelog (#17394)
• bump idb-keyval to v6 (#17393)
• bump web-features to v3.43.0 (#17391)
• bump acorn to v8.19.0 (#17390)
• bump @testing-library/preact and remove @testing-library/preact-hooks (#17389)
• bump pako to v3 (#17387)
• bump devDependencies and move ajv to devDependencies (#17386)
• bump runtime dependencies (#17385)
• replace rollup-plugin-polyfill-node with native Web API shims (#17375)
• remove angular devDependency (#17373)
• replace @typescript-eslint packages with typescript-eslint (#17372)
• bump jest and expect packages to v30 (#17371)
• remove eslint-formatter-codeframe (#17370)
• remove lookup-closest-locale (#17369)
• upgrade trace_engine to 0.0.67 (#17379)
• replace @esbuild-kit/esm-loader with tsx (#17367)
• upgrade mocha to 12.0.3 (#17360)
• inline eslint-config-google and remove eslint compat packages (#17359)
• migrate Node.js helper packages to native APIs (#17358)
• bump jsdom to v29 (#17357)
• bump eslint-plugin-import to v2.32 and remove @eslint/compat (#17356)
• replace chalk and colors with util.styleText (#17354)
• remove unused and redundant devDependencies (#17353)
• upgrade yargs to 18.2.0 and yargs-parser to 22.0.0 (#17351)
• remove unused ws and @types/ws (#17352)
• remove lodash-es (#17350)
• upgrade minor/patch dependencies (#17325)
• upgrade archiver to 8.0.0 (#17154)
• upgrade handlebars to 4.7.10 (#17308)
• upgrade trace_engine to 0.0.66 (#17307)
• pin to specific axe-core (#17279)
• upgrade deps (#17256)

Clients

• lr: ignore WebSocket console errors in Lightrider (#17414)
• lr: close page after gather (#17285)

Docs

• remove outdated related projects from readme (#17410)
• convert agentic-web issue template to GitHub issue form (#17366)
• quote name in agentic-web issue template front matter (#17272)
• cli: mention directory support in --output-path description (#17413)

Tests

• add regression tests for CommonJS support (#17339)
• remove mocha worker isolation and fix cross-test state contamination (#17329)
• restore jest-mock spies in afterEach (#17328)
• assert expectations for INTERNAL_LANTERN_USE_TRACE (#17314)
• update expectations for M157 favicon cache clearing (#17311)
• cli: update expected filename prefix in run-test (#17409)
• devtools: stringify to avoid V8 returnByValue limit (#17429)
• devtools: sync e2e tests (#17335)
• devtools: speed up devtools CI workflow (#17313)
• lantern: update golden trace dataset for 2026 (#17411)
• lantern: check all keys, run on trace-engine/package.json changes (#17322)
• lantern: restore test-lantern in CI using GitHub release assets (#17316)
• legacy-javascript: declare core-js in package.json, dedupe lockfile (#17302)
• legacy-javascript: fix build cache, rollup resolution, test assertions (#17296)
• network-request: add renderBlocking roundtrip (#17263)
• package-test: use local static server URL and retry fast run (#17430)
• package-test: run smoke subset and drop redundant build-report (#17317)
• smoke: exhaustively assert expected baseline features (#17326)
• smoke: use WebRTC instead of unload to trigger bf-cache failure in dbw (#17348)
• smoke: update flags required for WebMCP smoke tests (#17270)
• smoke: disable webmcp (#17278)
• smokehouse: log runner output on non-timeout runner errors (#17424)
• smokehouse: fix static-server reuse and runner error logging (#17284)
• smokehouse: fix retry state, timeout cleanup, and error logging (#17276)
• smokehouse: fix assertion and version check bugs (#17275)
• tbt-impact-tasks: pass networkRecords to createTestTrace (#16870)

Misc

• sanitize header URL links in treemap and flow-report (#17443)
• add skill for updating trace_engine (#17380)
• replace getModuleDirectory with import.meta.dirname (#17341)
• build: convert changelog-generator and commitlint configs to ESM (#17343)
• build: escape non-ASCII characters in bundle (#17345)
• ci: enable yarn cache on setup-node across workflows (#17319)
• ci: remove duplicate unit-lantern-trace and deduplicate test-viewer (#17318)
• ci: cancel superseded PR runs and balance smoke shards (#17321)
• ci: remove broken buildtracker, dead dogfood-lhci, and unused docs install (#17320)
• ci: pin actions to shas, fix zizmor findings, and add zizmor script (#17315)
• lint: remove obsolete eslint-local-rules.cjs (#17342)
• release: fix empty contributors check and null commit headers (#17420)
• release: simplify changelog generation (#17249)
• scripts: remove dead fallback in pptr-run-devtools (#17453)
• scripts: use timers/promises for sleeps (#17440)
• sentry: add browser version context (#17381)
• treemap: sanitize JSON in injectOptions (#17444)
• viewer: validate gist ID in getGistFileContentAsJson (#17447)
• viewer: prevent web crawlers from triggering PSI runs (#17384)