Implements the page-side surface of the W3C WebMCP spec
(https://webmachinelearning.github.io/webmcp/): exposes
`navigator.modelContext.registerTool(...)` for declaring MCP tools to a
browser agent, with full name/description validation, AbortSignal-based
unregistration, and a `ModelContextClient` whose `requestUserInteraction`
invokes its callback directly (closest faithful behavior in a headless
browser).
This is just moving fields around. The end result is that there's a
`transfer.req` and a `transfer.res`.
On the Request side, we use to have a nested `params: RequestParam` resulting
in a lot of `transfer.req.params.url`. This is now `transfer.req.url`. On the
Response side, we had the exact opposite: response fields splattered directly
in the transfer, `transfer.response_header`. This is now `transfer.res.header`.
There is now an HttpClient.Response, which is the actual final response (which
could be for a transfer or something else, e.g the cache). And an
HttpClient.Transfer.Response which captures the inflight response data (and is
one of the polymorphic variants of the HttpClient.Response). Probably still not
ideal, but I'm not sure how to make it cleaner, and even if this is just an
intermediary step, I consider it an small win.
This allows pending destroys that have been accumulated to be cleaned up. In
normal operations, this likely isn't going to happen. But we see a some unit
tests create _many_ pages that never have the change to be cleaned up. The
result is that the next "normal" unit test, which actually runs enough through
Runner to trigger the cleanup, pays a huge cleanup price.
Arguably, for a test-only solution, we could create a session per test, or
have explicit cleanup in the test. But having 1 long-lasting session is useful
as it can show us these potential pitfalls AND, it isn't impossible that a
real-world case runs into similar issues.
CSSStyleSheet.insertRule previously detected at-rules in the parser
(has_skipped_at_rule) and returned the requested index without inserting
anything. The original change (PR #1972) did this to keep at-rule input
from killing module evaluation in apps like Expo Web -- correct, but the
silent-success contract has a second-order effect: CSS-in-JS libraries
(emotion, styled-components, Stitches, Mantine, Linaria) that round-trip
through cssRules to deduplicate their stylesheets see the rule as missing
after insertion, conclude the stylesheet is empty, and fall back to direct
<style> element injection per render. The result is unbounded <style>
accumulation on long-lived sessions doing repeated DOM interaction. See
issue #2459 for measurements (Allbirds-style PDPs accumulating thousands
of <style> elements over a render loop).
Changes:
* Parser.RulesIterator now returns a Rule union of {.style, .at_rule}
instead of skipping at-rules and setting has_skipped_at_rule. The
at-rule variant carries the keyword (without `@`) and the full source
span so callers can construct an opaque placeholder rule.
* CSSRule gains a `_text` field and an `initAtRule` constructor for
storing the at-rule source. CSSRule.getCssText returns the stored
text (CSSStyleRule's overridden getCssText still wins for `.style`
rules via the bridge dispatch on the most-derived class).
* CSSStyleSheet.insertRule and replaceSync handle both Rule variants:
regular rules become CSSStyleRule as before, at-rules become opaque
CSSRule placeholders with the matching CSSRule.Type variant
(vendor-prefixed keyframes are normalized; unrecognized at-rule
keywords fall back to .media). The CSS engine still doesn't apply
these rules -- that's intentional and outside the scope of this
change -- but they now surface via cssRules so library dedup paths
work correctly.
* StyleManager.addRawRules switches on the Rule kind and skips
at-rules (it only filters on display/visibility/opacity at the top
level, no semantic change).
* The CSSRule spec constants (STYLE_RULE, KEYFRAMES_RULE, MEDIA_RULE,
...) were declared as plain Zig consts inside JsApi but never wrapped
with bridge.property, so they came back as `undefined` from JS. Fixed
while writing the regression tests since the tests need to compare
rule.type against the spec constants.
Tests:
* Parser unit tests: cover statement at-rules (`@import url(...);`),
block at-rules (`@media`), and vendor-prefixed at-rules
(`@-webkit-keyframes`).
* HTML runner tests: cover insertRule for @keyframes, @media,
@supports, @font-face, vendor-prefixed at-rules, mixed style + at-rule
insertion, replaceSync at-rule preservation, and the dedup-via-cssRules
pattern that's the actual library code path the bug breaks.
A/B verification with the synthetic CSS-in-JS dedup pattern (50 calls to
inject the same @keyframes through a library that falls back to <style>
element injection when insertRule appears empty):
baseline (1.0.0-nightly.6240): styles=51 rules=0
patched (this branch): styles=1 rules=50
The leak collapses: instead of 50 <style> fallbacks stacking up, the
single persistent stylesheet receives all 50 insertions and dedup works.
Note on partial coverage of #2459: the original Allbirds reproducer
involves a Vue.js + Yotpo widget that injects <style> elements via
direct document.head.appendChild rather than insertRule. That code
path is unaffected by this change; it appears to be a separate
mechanism (possibly related to Vue's vue-style-loader closure-based
dedup or web-component lifecycle on Lightpanda) and is worth filing
separately. This PR fixes the specific insertRule contract issue
described in #2459 and unblocks the major CSS-in-JS libraries.
- Filter redundant `extract` calls in recordings to reduce noise.
- Scrub literal `LP_*` secrets from recorded commands for portability.
- Throw a descriptive error in `extract` when no selectors match.
- Update tool descriptions and guidance to favor a `tree` ->
`nodeDetails` -> `extract` workflow for more robust selectors.
- Add `callEvalLike` to consolidate tools returning `EvalResult`.
- Update `Agent` and `MCP` to use the new helper.
- Route failed data commands to stderr in `CommandExecutor`.
- Update CSS selector guidance in `script.zig`.
Adds the `extract` tool for lifting structured data via JSON schemas.
Updates the command system to support recording and replaying
extraction steps in PandaScript.
Replaces the struct-based result with a tagged union to represent
verification outcomes more idiomatically. Updates callers in Agent
and MCP tools to handle the new union type.
- Remove `extractText` from browser tools and `ToolExecutor`
- Update MCP `extract` step to use `extractSchema` instead of a selector
- Remove `allocator` and `execute` method from `CommandExecutor`
The submitForm encoding path was the last duplicate of the "limited to
only known values" canonicalization the previous commit consolidated for
the IDL getters. Now it consumes the same Form.normalizeMethod /
Form.normalizeEnctype helpers, so a single function owns the canonical
mapping (`""` / unknown -> spec default, recognized values pass through
unchanged).
Side effect of routing through the helper: the
`log.warn(.not_implemented, "FormData.encoding", ...)` branch falls out.
After commit 4b693db4 added `text/plain`, the only attribute values that
still reach the urlencoded fallback are spec-invalid ones, which per
HTML §4.10.21.5 silently canonicalize to
`application/x-www-form-urlencoded`. The warning was firing for valid
spec behavior — Chrome doesn't log either.
Behavior-preserving on all observable surfaces: full suite 639/639 green;
existing form-submission integration tests (multipart, urlencoded,
text/plain, GET-ignores-enctype) all pass unchanged.
Adrià Arrufat