feat(packages): add dsh-plugin-browserskill — DeepSeek Harness tools for bsk

Add a new monorepo package that registers BrowserSkill (bsk) browser
automation as model-visible tools in DeepSeek Harness (dsh):

- 11 tools mapping to bsk CLI --json commands: session start/stop/list,
  navigate, snapshot, observe, click, fill, press, screenshot, emulate
- multi-session support: optional session arg with a current-session
  pointer, session id echoed in every result, configurable concurrency
  cap (default 5), and dispose-time cleanup of plugin-started sessions
- cancellation: exec.signal aborts kill the underlying bsk child process
- terminal-style UI cards (command line as the call card, output as the
  result card); screenshots inline the PNG through the host attachment
  store when the model route accepts image input, else return the path
- config: bskPath / defaultTimeoutMs / maxSessions via Schemastery schema
- install guidance when the bsk binary is missing; bsk JSON error
  envelopes (code/message/hint) surfaced to the model
- unit tests mock the bsk runner (no real browser required); the root
  lint script now also runs the package's typecheck + tests so the
  existing CI frontend job covers the new package (a dedicated CI job
  diff is provided in the PR; the pushing token lacks workflow scope)

packages/dsh-plugin-browserskill/src/index.ts

@@ -0,0 +1,80 @@
+/**
+ * dsh-plugin-browserskill — a DeepSeek Harness bundle that registers
+ * BrowserSkill (`bsk`) browser automation as model-visible tools.
+ *
+ * Each tool spawns `bsk <cmd> --json`, parses the structured output, and
+ * returns a canonical JSON value. The plugin tracks the sessions it starts so
+ * one agent conversation can drive several browsers at once; unloading the
+ * plugin stops every tracked session and kills any in-flight bsk children.
+ *
+ * @module dsh-plugin-browserskill
+ */
+
+import type { Context } from "@deepseek-ai/cordis";
+import Schema from "@deepseek-ai/schemastery";
+import { createBskRunner } from "./runner";
+import { SessionRegistry } from "./sessions";
+import { type PluginConfig, registerTools } from "./tools";
+
+export const name = "dsh-plugin-browserskill";
+export const inject = ["tools"];
+
+/** Runtime configuration schema (validated and defaulted by Cordis). */
+export const Config = Schema.object({
+  bskPath: Schema.string()
+    .default("bsk")
+    .description("Path to the bsk CLI binary (defaults to resolving `bsk` from PATH)."),
+  defaultTimeoutMs: Schema.number()
+    .default(120_000)
+    .description("Default per-command timeout in milliseconds."),
+  maxSessions: Schema.number()
+    .default(5)
+    .description("Maximum number of concurrent browser sessions started through this plugin."),
+});
+
+export type Config = PluginConfig;
+
+export function apply(ctx: Context, config: Partial<PluginConfig> = {}): void {
+  const resolved: PluginConfig = {
+    bskPath: config.bskPath ?? "bsk",
+    defaultTimeoutMs: config.defaultTimeoutMs ?? 120_000,
+    maxSessions: config.maxSessions ?? 5,
+  };
+  const runner = createBskRunner(resolved.bskPath);
+  const registry = new SessionRegistry(resolved.maxSessions);
+
+  registerTools({ ctx, runner, registry, config: resolved });
+
+  // Non-blocking install probe: warn early when bsk is missing instead of
+  // failing the first tool call with a bare spawn error.
+  runner.run(["status"], { timeoutMs: 10_000 }).then(
+    () => {},
+    (error: unknown) => {
+      const detail = error instanceof Error ? error.message : String(error);
+      console.warn(
+        `[${name}] bsk probe failed (${detail}); browser tools will report install guidance until the bsk CLI is available`,
+      );
+    },
+  );
+
+  // Unload cleanup: kill in-flight children, then stop every session this
+  // plugin started (best effort; sessions started outside the plugin are
+  // left running).
+  ctx.effect(() => {
+    return () => {
+      runner.killAll();
+      const stops = registry
+        .list()
+        .map((session) =>
+          runner.run(["session", "stop", session.sessionId], { timeoutMs: 15_000 }).catch(() => {}),
+        );
+      return Promise.all(stops).then(() => {});
+    };
+  });
+}
+
+export type { BskRunner, BskRunResult, SpawnImpl } from "./runner";
+export { BskError, createBskRunner } from "./runner";
+export { SessionRegistry } from "./sessions";
+export type { PluginConfig, ToolDeps } from "./tools";
+export { registerTools } from "./tools";