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feat(mcp): emit structured snapshot in --json responses - #42098

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pavelfeldman merged 1 commit into
microsoft:mainfrom
pavelfeldman:fix-42076
Aug 3, 2026
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feat(mcp): emit structured snapshot in --json responses#42098
pavelfeldman merged 1 commit into
microsoft:mainfrom
pavelfeldman:fix-42076

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@pavelfeldman pavelfeldman commented Aug 3, 2026

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Summary

  • Add Page.ariaSnapshotJSON and Locator.ariaSnapshotJSON returning the aria snapshot as a free form JSON object
  • MCP response sections can now carry structured content; inline snapshots in --json replies are emitted as the node tree instead of YAML text

Fixes #42076

yury-s
yury-s approved these changes Aug 3, 2026
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Comment thread docs/src/api/class-locator.md
* `name` <[string]> Accessible name of the element, if any.
* `text` <[string]> Text content of the element, when it is the only child.
* `children` <[Array]> Child nodes and text fragments.
* Boolean and value properties for element state flags: `checked`, `disabled`, `expanded`, `active`, `invalid`, `level`, `pressed` and `selected`.

@yury-s yury-s Aug 3, 2026

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* Boolean and value properties for element state flags: `checked`, `disabled`, `expanded`, `active`, `invalid`, `level`, `pressed` and `selected`.

What does this mean? Should it be just a list of boolean/number optional properties one per line?

@pavelfeldman pavelfeldman Aug 3, 2026

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We don't want to over-specify this type as it is a subject to change.

Comment thread packages/playwright-core/src/server/page.ts
// Note: the resolved frame might differ from the original |frame|.
// See https://developer.mozilla.org/en-US/docs/Web/API/Document/body for body/frameset explanation.
// Non-strict, because pages with nested framesets have multiple "frameset" elements.
const resolved = await progress.race(frame.selectors.callOnSelector(selector || 'body,frameset', { strict: options.strict ?? !!selector, noDefaultPierce: !selector || options.noDefaultPierce }, ({ injected, elements }, ariaOptions) => {

@yury-s yury-s Aug 3, 2026

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do we actually care about framesets here?

@pavelfeldman pavelfeldman Aug 3, 2026

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This is a pure parity with the regular snapshot

@pavelfeldman
feat(mcp): emit structured snapshot in --json responses
d70649f 
Add Page.ariaSnapshotJSON and Locator.ariaSnapshotJSON that return the
aria snapshot as a free form JSON object. MCP response sections can now
carry structured content, so inline snapshots in --json replies are
emitted as the node tree instead of YAML text.

Fixes: microsoft#42076
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github-actions Bot commented Aug 3, 2026

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🔴 One failure looks caused by this PR

Hi, I'm the Playwright bot and I took a first look at the CI failures.

mcp/cli-json.spec.ts › snapshot returns structured children and flags fails on WebKit across all three OSes — it's the test this PR adds, and the new structured-snapshot feature omits cursor: "pointer" on WebKit. The Firefox annotate failure is a known flake, unrelated to this PR.

Details

Caused by this PR

  • [webkit] › mcp/cli-json.spec.ts › snapshot returns structured children and flags (ubuntu + macos + windows) — the test added in this PR. It only exists on this PR's runs and fails on WebKit in all 3 attempts while passing on chromium/chrome/firefox/msedge. The diff reaches it directly: the new ariaSnapshotJSON node emits a cursor field, but WebKit doesn't report cursor: "pointer" the way the test expects, so the assertion drops that key:

    - "cursor": "pointer",
  "name": "Link",
  "role": "link",

    Either the cursor detection in the new snapshot code needs to work on WebKit, or the expectation should account for the engine difference (e.g. drop the cursor assertion or gate that part).

Pre-existing flake / infra

Triaged by the Playwright bot - agent run

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Test results for "MCP"

7920 passed, 1284 skipped

Merge workflow run.

@pavelfeldman

pavelfeldman commented Aug 3, 2026

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@microsoft-github-policy-service rerun

@pavelfeldman
pavelfeldman merged commit ea4ea1f into microsoft:main Aug 3, 2026
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Test results for "tests 1"

1 flaky ⚠️ [playwright-test] › ui-mode-trace.spec.ts:827 › should update state on subsequent run `@windows-latest-node22`

51198 passed, 1188 skipped

Merge workflow run.

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[CLI]: --json emits formatted text wrapped in a string, not structured data

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