Add named Playwright executor support to browsers playwright commands (#281)

## 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.

---------

Co-authored-by: rgarcia <72655+rgarcia@users.noreply.github.com>

Author: rgarcia

README.md

@@ -1009,8 +1009,12 @@ Destinations are the OTLP/HTTP endpoints sessions export to. They belong to the
 ### Browser Playwright
 
 - `kernel browsers playwright execute <id> [code]` - Execute Playwright/TypeScript code against the browser
+  - `--executor <name>` - Executor to run the call in. Calls on different executors run concurrently in separate tabs of the same browser; calls on one executor run one at a time. Omit to use the always-present `default` executor bound to the active tab. Any other name creates a named executor on first use that owns a background tab `page` is bound to. At most 8 named executors per browser (409 when exceeded)
   - `--timeout <seconds>` - Maximum execution time in seconds (defaults server-side)
   - If `[code]` is omitted, code is read from stdin
+- `kernel browsers playwright executors list <id>` - List the browser's Playwright executors (default first) with busy state, timestamps, and the tab each named executor owns
+- `kernel browsers playwright executors delete <id> <executor>` - Delete a Playwright executor. Deleting `default` restarts it instead of removing it
+  - `--close-tab` - Close the tab owned by the executor (default: true)
 
 ### Browser REPL
 
@@ -1524,6 +1528,15 @@ TS
 # With a timeout in seconds
 kernel browsers playwright execute my-browser --timeout 30 'await (await context.newPage()).goto("https://example.com")'
 
+# Drive two tabs in parallel with named executors (each owns its own tab)
+kernel browsers playwright execute my-browser --executor docs 'await page.goto("https://example.com/docs"); return await page.title();' &
+kernel browsers playwright execute my-browser --executor pricing 'await page.goto("https://example.com/pricing"); return await page.title();' &
+wait
+
+# List executors and delete one (closes its tab unless --close-tab=false)
+kernel browsers playwright executors list my-browser
+kernel browsers playwright executors delete my-browser docs
+
 # Mini CDP connection load test (10s)
 cat <<'TS' | kernel browsers playwright execute my-browser
 const start = Date.now();

cmd/browsers.go

@@ -90,11 +90,6 @@ type BrowserLogService interface {
 	StreamStreaming(ctx context.Context, idOrName string, query kernel.BrowserLogStreamParams, opts ...option.RequestOption) (stream *ssestream.Stream[shared.LogEvent])
 }
 
-// BrowserPlaywrightService defines the subset we use for Playwright execution.
-type BrowserPlaywrightService interface {
-	Execute(ctx context.Context, idOrName string, body kernel.BrowserPlaywrightExecuteParams, opts ...option.RequestOption) (res *kernel.BrowserPlaywrightExecuteResponse, err error)
-}
-
 // BrowserComputerService defines the subset we use for OS-level mouse & screen.
 type BrowserComputerService interface {
 	Batch(ctx context.Context, idOrName string, body kernel.BrowserComputerBatchParams, opts ...option.RequestOption) (err error)
@@ -517,16 +512,17 @@ type BrowsersUpdateInput struct {
 
 // BrowsersCmd is a cobra-independent command handler for browsers operations.
 type BrowsersCmd struct {
-	browsers   BrowsersService
-	replays    BrowserReplaysService
-	fs         BrowserFSService
-	fsWatch    BrowserFWatchService
-	process    BrowserProcessService
-	logs       BrowserLogService
-	computer   BrowserComputerService
-	playwright BrowserPlaywrightService
-	telemetry  BrowserTelemetryService
-	webmcp     BrowserWebMCPService
+	browsers            BrowsersService
+	replays             BrowserReplaysService
+	fs                  BrowserFSService
+	fsWatch             BrowserFWatchService
+	process             BrowserProcessService
+	logs                BrowserLogService
+	computer            BrowserComputerService
+	playwright          BrowserPlaywrightService
+	playwrightExecutors BrowserPlaywrightExecutorService
+	telemetry           BrowserTelemetryService
+	webmcp              BrowserWebMCPService
 }
 
 type BrowsersListInput struct {
@@ -1836,64 +1832,6 @@ type BrowsersFSWatchEventsInput struct {
 	WatchID    string
 }
 
-// Playwright
-type BrowsersPlaywrightExecuteInput struct {
-	Identifier string
-	Code       string
-	Timeout    int64
-	Output     string
-}
-
-func (b BrowsersCmd) PlaywrightExecute(ctx context.Context, in BrowsersPlaywrightExecuteInput) error {
-	if err := validateJSONOutput(in.Output); err != nil {
-		return err
-	}
-
-	if b.playwright == nil {
-		pterm.Error.Println("playwright service not available")
-		return nil
-	}
-	br, err := b.browsers.Get(ctx, in.Identifier, kernel.BrowserGetParams{})
-	if err != nil {
-		return util.CleanedUpSdkError{Err: err}
-	}
-	params := kernel.BrowserPlaywrightExecuteParams{Code: in.Code}
-	if in.Timeout > 0 {
-		params.TimeoutSec = kernel.Opt(in.Timeout)
-	}
-	res, err := b.playwright.Execute(ctx, br.SessionID, params)
-	if err != nil {
-		return util.CleanedUpSdkError{Err: err}
-	}
-
-	if in.Output == "json" {
-		return util.PrintPrettyJSON(res)
-	}
-
-	rows := pterm.TableData{{"Property", "Value"}, {"Success", fmt.Sprintf("%t", res.Success)}}
-	PrintTableNoPad(rows, true)
-
-	if res.Stdout != "" {
-		pterm.Info.Println("stdout:")
-		fmt.Println(res.Stdout)
-	}
-	if res.Stderr != "" {
-		pterm.Info.Println("stderr:")
-		fmt.Fprintln(os.Stderr, res.Stderr)
-	}
-	if res.Result != nil {
-		bs, err := json.MarshalIndent(res.Result, "", "  ")
-		if err == nil {
-			pterm.Info.Println("result:")
-			fmt.Println(string(bs))
-		}
-	}
-	if !res.Success && res.Error != "" {
-		pterm.Error.Printf("error: %s\n", res.Error)
-	}
-	return nil
-}
-
 // REPL
 type BrowsersReplInput struct {
 	Identifier string
@@ -3201,13 +3139,7 @@ func init() {
 	computerRoot.AddCommand(computerClick, computerMove, computerScreenshot, computerType, computerPressKey, computerScroll, computerDrag, computerSetCursor, computerGetMousePosition, computerBatch, computerReadClipboard, computerWriteClipboard)
 	browsersCmd.AddCommand(computerRoot)
 
-	// playwright
-	playwrightRoot := &cobra.Command{Use: "playwright", Short: "Playwright operations"}
-	playwrightExecute := &cobra.Command{Use: "execute <id> [code]", Short: "Execute Playwright/TypeScript code against the browser", Args: cobra.MinimumNArgs(1), RunE: runBrowsersPlaywrightExecute}
-	playwrightExecute.Flags().Int64("timeout", 0, "Maximum execution time in seconds (default per server)")
-	addJSONOutputFlag(playwrightExecute)
-	playwrightRoot.AddCommand(playwrightExecute)
-	browsersCmd.AddCommand(playwrightRoot)
+	browsersCmd.AddCommand(newBrowsersPlaywrightCommand())
 
 	// repl
 	replCmd := &cobra.Command{
@@ -3828,33 +3760,6 @@ func runBrowsersFSWatchEvents(cmd *cobra.Command, args []string) error {
 	return b.FSWatchEvents(cmd.Context(), BrowsersFSWatchEventsInput{Identifier: args[0], WatchID: args[1]})
 }
 
-func runBrowsersPlaywrightExecute(cmd *cobra.Command, args []string) error {
-	client := getKernelClient(cmd)
-	svc := client.Browsers
-
-	var code string
-	if len(args) >= 2 {
-		code = strings.Join(args[1:], " ")
-	} else {
-		// Read code from stdin
-		stat, _ := os.Stdin.Stat()
-		if (stat.Mode() & os.ModeCharDevice) != 0 {
-			pterm.Error.Println("no code provided. Provide code as an argument or pipe via stdin")
-			return nil
-		}
-		data, err := io.ReadAll(os.Stdin)
-		if err != nil {
-			pterm.Error.Printf("failed to read stdin: %v\n", err)
-			return nil
-		}
-		code = string(data)
-	}
-	timeout, _ := cmd.Flags().GetInt64("timeout")
-	output, _ := cmd.Flags().GetString("output")
-	b := BrowsersCmd{browsers: &svc, playwright: &svc.Playwright}
-	return b.PlaywrightExecute(cmd.Context(), BrowsersPlaywrightExecuteInput{Identifier: args[0], Code: strings.TrimSpace(code), Timeout: timeout, Output: output})
-}
-
 func runBrowsersRepl(cmd *cobra.Command, args []string) error {
 	client := getKernelClient(cmd)
 	svc := client.Browsers