Add named Playwright executor support to browsers playwright commands

[rgarcia]

Summary

Adds named Playwright executor support to kernel browsers playwright.

• kernel browsers playwright execute --executor <name>: runs the call in a named executor (sent only when set). Help text explains concurrency across executors, serialization within one, the always-present default executor bound to the active tab, named executors owning a background tab that page is bound to, and the limit of 8 named executors.
• The execute result now shows the tab the call was bound to (Tab Target ID, Tab Created) in the table output; JSON output passes it through from the API response.
• A 409 from execute (executor limit reached) is rendered as the API message followed by the current executors (name, busy marker, tab URL) and the delete command to run, instead of the generic error formatting.
• New kernel browsers playwright executors list <id-or-name>: table of name, busy, created at, last used at, target ID, URL (default first); supports -o json.
• New kernel browsers playwright executors delete <id-or-name> <executor> [--close-tab]: --close-tab defaults to true and is only sent when set explicitly. Deleting default reports a restart rather than a deletion, matching API semantics.
• The playwright command group is now built by newBrowsersPlaywrightCommand() so it can be exercised in tests the same way the webmcp group is.
• README command reference and examples updated.

Dependencies

Bumps github.com/kernel/kernel-go-sdk to v0.120.0 (released), which adds the executors surface: BrowserPlaywrightExecuteParams.Executor, Tab on the execute response, BrowserPlaywrightExecutorService.List/Delete, Executor, and ExecutorList.

Tests

cmd/browsers_playwright_executors_test.go covers command wiring and flag defaults, the executor request param (absent vs set), tab rendering in table and JSON output, the 409 limit error, list table/JSON rendering, delete path and close_tab query handling, API error cleanup, and argument validation, using an httptest server like the webmcp tests.

go build ./..., go vet ./..., go test ./..., and golangci-lint run all pass locally.

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 99617b9. Configure here.}

[masnwilliams]

lgtm, solid change and the httptest coverage is thorough. one thing worth fixing before merge (inline on the 409 path), the rest are optional:

• file layout: newBrowsersPlaywrightCommand() now defines execute in this file, but PlaywrightExecute / BrowsersPlaywrightExecuteInput / runBrowsersPlaywrightExecute / BrowserPlaywrightService still live in browsers.go. might be cleaner as browsers_playwright.go owning the whole group like browsers_webmcp.go does. also BrowsersCmd.executors -> playwrightExecutors reads less ambiguously next to the other service fields.
• --executor usage string: it restates playwrightExecutorsLong, which is already in execute's Long. a one-liner like Named executor to run the call in; each owns its own tab (default: the active tab) would do, and keeps the server's limit of 8 out of one more place.
• follow-up: execute still does browsers.Get then calls with SessionID, while Execute takes id-or-name directly like the new list/delete do. pre-existing, but dropping it saves a round trip per call.
• tests: TestPlaywrightExecuteOutput branches on strings.Contains(tc.response, "tab"). an explicit wantTab field would be clearer. strings.Count(rows[1], " - ") == 2 is a bit tied to table padding.
• the ci-fix comment / ci-fix/hypeship/playwright-executors branch are stale now that v0.120.0 is out, probably worth deleting so nobody opens a PR from it.

[masnwilliams]

+1 to bugbot here. i ran this through renderCommandError with fang's ErrorText transform (strings.Fields + Join) and it comes out as one line:

ERROR  Browser already has 8 named Playwright executors Current executors: default checkout (busy) https://example.com/cart Delete one with 'kernel browsers playwright executors delete <id-or-name> <executor>'

simplest fix is probably a single-line hint with the real identifier and a pointer to executors list, since that already renders the executors:

var apiErr *kernel.Error
if errors.As(err, &apiErr) && apiErr.StatusCode == http.StatusConflict && in.Executor != "" {
	// Not %w: the root handler re-renders any wrapped *kernel.Error as "code: message", dropping the hint.
	return fmt.Errorf("%s. See them with 'kernel browsers playwright executors list %s' and free one with 'kernel browsers playwright executors delete %s <executor>'", util.CleanedUpSdkError{Err: err}, in.Identifier, in.Identifier)
}

that also avoids treating every 409 as the executor limit. if you'd rather keep the multi-line list, the fix belongs in renderCommandError (generalize the PromptError carve-out into a "preformatted" error interface).

[rgarcia]

Took this approach in 47ab106, with one tweak: the limit body has no code field, so CleanedUpSdkError would render : message. The hint reads message from the body directly instead and falls back to the generic rendering when it is missing. Guarded on in.Executor != "" as you suggested. Test updated to pin the exact single-line string.

[rgarcia]

Addressed in 47ab106:

• 409 path: single-line hint with the real identifier, per the inline thread.
• file layout: the whole playwright group (execute, executors list/delete, service interfaces, inputs, run funcs) now lives in cmd/browsers_playwright.go, with cmd/browsers_playwright_test.go alongside. BrowsersCmd.executors renamed to playwrightExecutors.
• --executor usage: trimmed to the one-liner; the long explanation and the limit of 8 stay only in the command's Long text.
• tests: TestPlaywrightExecuteOutput uses an explicit wantTab field; the padding-dependent " - " count is replaced with content assertions.
• stale ci-fix: deleted the ci-fix/hypeship/playwright-executors branch and its comment.
• browsers.Get round trip: left as is for this PR since it is pre-existing behavior; happy to drop it in a follow-up.