Add Linear issue worktree workflow

config/pi/extensions/worktree-agent/guard.ts

@@ -0,0 +1,62 @@
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
+
+const PATH_TOOLS = new Set(["read", "write", "edit", "grep", "find", "ls"]);
+
+function isWithin(root: string, candidate: string): boolean {
+  const relative = path.relative(root, candidate);
+  return relative === "" || (!relative.startsWith(`..${path.sep}`) && relative !== ".." && !path.isAbsolute(relative));
+}
+
+function canonicalizePotentialPath(inputPath: string, cwd: string): string {
+  let normalized = inputPath.startsWith("@") ? inputPath.slice(1) : inputPath;
+  if (normalized === "~") normalized = os.homedir();
+  else if (normalized.startsWith(`~${path.sep}`)) normalized = path.join(os.homedir(), normalized.slice(2));
+
+  const resolved = path.resolve(cwd, normalized);
+  const missingSegments: string[] = [];
+  let existing = resolved;
+
+  while (!fs.existsSync(existing)) {
+    const parent = path.dirname(existing);
+    if (parent === existing) break;
+    missingSegments.unshift(path.basename(existing));
+    existing = parent;
+  }
+
+  const canonicalBase = fs.existsSync(existing) ? fs.realpathSync(existing) : existing;
+  return path.join(canonicalBase, ...missingSegments);
+}
+
+export function registerWorkerGuard(pi: ExtensionAPI, configuredRoot: string): void {
+  const root = fs.realpathSync(configuredRoot);
+
+  pi.on("tool_call", async (event) => {
+    if (!PATH_TOOLS.has(event.toolName)) return;
+
+    const input = event.input as { path?: unknown };
+    if (input.path === undefined && (event.toolName === "grep" || event.toolName === "find" || event.toolName === "ls")) {
+      return;
+    }
+    if (typeof input.path !== "string") {
+      return { block: true, reason: `${event.toolName} requires a path inside the assigned worktree.` };
+    }
+
+    const target = canonicalizePotentialPath(input.path, root);
+    if (!isWithin(root, target)) {
+      return {
+        block: true,
+        reason: `Worker file tools are restricted to ${root}. Attempted path: ${input.path}`,
+      };
+    }
+  });
+
+  pi.on("before_agent_start", async (event) => ({
+    systemPrompt:
+      event.systemPrompt +
+      `\n\nYou are running as a worktree worker. Your assigned repository root is ${root}. ` +
+      "Keep all file mutations and shell work inside this worktree. Do not access or modify sibling worktrees.",
+  }));
+}