feat: implement Cloud Git Worktree Pool in agent-runner to isolate parallel sessions

vibn-agent-runner/src/server.ts

@@ -24,41 +24,100 @@ const PORT = process.env.PORT || 3333;
 // Build ToolContext from environment variables
 // ---------------------------------------------------------------------------
 
-function ensureWorkspace(repo?: string): string {
+function ensureWorkspace(repo?: string, sessionId?: string): string {
   const base = process.env.WORKSPACE_BASE || "/workspaces";
   if (!repo) {
     const dir = path.join(base, "default");
     fs.mkdirSync(dir, { recursive: true });
     return dir;
   }
-  const dir = path.join(base, repo.replace("/", "_"));
+  const mainRepoDir = path.join(base, repo.replace("/", "_"));
   const gitea = {
     apiUrl: process.env.GITEA_API_URL || "",
     apiToken: process.env.GITEA_API_TOKEN || "",
     username: process.env.GITEA_USERNAME || "",
   };
-  if (!fs.existsSync(path.join(dir, ".git"))) {
-    fs.mkdirSync(dir, { recursive: true });
+
+  // 1. Ensure main repo clone exists
+  if (!fs.existsSync(path.join(mainRepoDir, ".git"))) {
+    fs.mkdirSync(mainRepoDir, { recursive: true });
     const authedUrl = `${gitea.apiUrl}/${repo}.git`.replace(
       "https://",
       `https://${gitea.username}:${gitea.apiToken}@`,
     );
     try {
-      execSync(`git clone "${authedUrl}" "${dir}"`, { stdio: "pipe" });
+      execSync(`git clone "${authedUrl}" "${mainRepoDir}"`, { stdio: "pipe" });
     } catch {
       // Repo may not exist yet — just init
-      execSync(`git init`, { cwd: dir, stdio: "pipe" });
+      execSync(`git init`, { cwd: mainRepoDir, stdio: "pipe" });
       execSync(`git remote add origin "${authedUrl}"`, {
-        cwd: dir,
+        cwd: mainRepoDir,
         stdio: "pipe",
       });
     }
   }
-  return dir;
+
+  // 2. If no sessionId, fall back to main repo clone directly
+  if (!sessionId) {
+    return mainRepoDir;
+  }
+
+  // 3. Isolated Worktree Directory per task session
+  const taskWorktreePath = path.join(base, "tasks", sessionId);
+  fs.mkdirSync(path.join(base, "tasks"), { recursive: true });
+
+  // 4. Create isolated worktree if not yet active
+  if (!fs.existsSync(path.join(taskWorktreePath, ".git"))) {
+    // Clean up any stale directory from previous failed runs before adding worktree
+    if (fs.existsSync(taskWorktreePath)) {
+      try {
+        fs.rmSync(taskWorktreePath, { recursive: true, force: true });
+      } catch {}
+    }
+
+    try {
+      console.log(
+        `[worktree] Adding isolated git worktree for session ${sessionId} at ${taskWorktreePath}...`,
+      );
+
+      // Check if the branch task-sessionId already exists in the main repository
+      let branchExists = false;
+      try {
+        const branches = execSync(`git branch --list "task-${sessionId}"`, {
+          cwd: mainRepoDir,
+        }).toString();
+        branchExists = branches.trim().length > 0;
+      } catch {
+        branchExists = false;
+      }
+
+      if (branchExists) {
+        // Checkout the existing branch into the new worktree path
+        execSync(
+          `git worktree add -f "${taskWorktreePath}" "task-${sessionId}"`,
+          { cwd: mainRepoDir, stdio: "pipe" },
+        );
+      } else {
+        // Create and checkout a new isolated branch
+        execSync(
+          `git worktree add -f -b "task-${sessionId}" "${taskWorktreePath}"`,
+          { cwd: mainRepoDir, stdio: "pipe" },
+        );
+      }
+    } catch (e: any) {
+      console.error(
+        "[worktree] Failed to add git worktree, falling back to main clone:",
+        e.message || String(e),
+      );
+      return mainRepoDir;
+    }
+  }
+
+  return taskWorktreePath;
 }
 
-function buildContext(repo?: string): ToolContext {
-  const workspaceRoot = ensureWorkspace(repo);
+function buildContext(repo?: string, sessionId?: string): ToolContext {
+  const workspaceRoot = ensureWorkspace(repo, sessionId);
 
   return {
     workspaceRoot,
@@ -77,6 +136,39 @@ function buildContext(repo?: string): ToolContext {
   };
 }
 
+function cleanupWorkspace(repo: string, sessionId: string) {
+  const base = process.env.WORKSPACE_BASE || "/workspaces";
+  const mainRepoDir = path.join(base, repo.replace("/", "_"));
+  const taskWorktreePath = path.join(base, "tasks", sessionId);
+
+  if (fs.existsSync(taskWorktreePath)) {
+    try {
+      console.log(
+        `[worktree] Pruning and removing git worktree for session ${sessionId}...`,
+      );
+      // 1. Tell git to remove the worktree references
+      execSync(`git worktree remove --force "${taskWorktreePath}"`, {
+        cwd: mainRepoDir,
+        stdio: "pipe",
+      });
+      // 2. Delete the temporary branch from the main repository index
+      execSync(`git branch -D "task-${sessionId}"`, {
+        cwd: mainRepoDir,
+        stdio: "pipe",
+      });
+      // 3. Force clean directory
+      if (fs.existsSync(taskWorktreePath)) {
+        fs.rmSync(taskWorktreePath, { recursive: true, force: true });
+      }
+    } catch (e: any) {
+      console.warn(
+        `[worktree] Non-fatal cleanup error for session ${sessionId}:`,
+        e.message || String(e),
+      );
+    }
+  }
+}
+
 // ---------------------------------------------------------------------------
 // Routes
 // ---------------------------------------------------------------------------
@@ -244,7 +336,7 @@ app.post("/agent/execute", async (req: Request, res: Response) => {
   // Build workspace context — clone/update the Gitea repo if provided
   let ctx: ReturnType<typeof buildContext>;
   try {
-    ctx = buildContext(giteaRepo);
+    ctx = buildContext(giteaRepo, sessionId);
   } catch (err) {
     const msg = err instanceof Error ? err.message : String(err);
     console.error("[agent/execute] buildContext failed:", msg);
@@ -332,6 +424,9 @@ app.post("/agent/execute", async (req: Request, res: Response) => {
     })
     .finally(() => {
       activeSessions.delete(sessionId);
+      if (giteaRepo && sessionId) {
+        cleanupWorkspace(giteaRepo, sessionId);
+      }
     });
 });