Implement --branch flag for dolt_add stored procedure

- Add supportsBranchFlag parameter to CreateAddArgParser
- Update CLI usages to use CreateAddArgParser(false)
- Update stored procedure to use CreateAddArgParser(true)
- Add branch handling logic using revision-qualified database names
- Add proper error handling for invalid branch names

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

go/cmd/dolt/cli/arg_parser_helpers.go

@@ -137,11 +137,14 @@ func CreatePushArgParser() *argparser.ArgParser {
 	return ap
 }
 
-func CreateAddArgParser() *argparser.ArgParser {
+func CreateAddArgParser(supportsBranchFlag bool) *argparser.ArgParser {
 	ap := argparser.NewArgParserWithVariableArgs("add")
 	ap.ArgListHelp = append(ap.ArgListHelp, [2]string{"table", "Working table(s) to add to the list tables staged to be committed. The abbreviation '.' can be used to add all tables."})
 	ap.SupportsFlag(AllFlag, "A", "Stages any and all changes (adds, deletes, and modifications) except for ignored tables.")
 	ap.SupportsFlag(ForceFlag, "f", "Allow adding otherwise ignored tables.")
+	if supportsBranchFlag {
+		ap.SupportsString(BranchParam, "", "branch", "Add to the specified branch instead of the current branch.")
+	}
 
 	return ap
 }

go/cmd/dolt/commands/add.go

@@ -70,12 +70,12 @@ func (cmd AddCmd) Description() string {
 }
 
 func (cmd AddCmd) Docs() *cli.CommandDocumentation {
-	ap := cli.CreateAddArgParser()
+	ap := cli.CreateAddArgParser(false)
 	return cli.NewCommandDocumentation(addDocs, ap)
 }
 
 func (cmd AddCmd) ArgParser() *argparser.ArgParser {
-	return cli.CreateAddArgParser()
+	return cli.CreateAddArgParser(false)
 }
 
 // generateAddSql returns the query that will call the `DOLT_ADD` stored proceudre.
@@ -111,7 +111,7 @@ func generateAddSql(apr *argparser.ArgParseResults) string {
 
 // Exec executes the command
 func (cmd AddCmd) Exec(ctx context.Context, commandStr string, args []string, _ *env.DoltEnv, cliCtx cli.CliContext) int {
-	ap := cli.CreateAddArgParser()
+	ap := cli.CreateAddArgParser(false)
 
 	// This flag is only supported in a CLI context, not the in the dolt procedure.
 	ap.SupportsFlag(cli.PatchFlag, "p", "Interactively select changes to add to the staged set.")

go/libraries/doltcore/sqle/dprocedures/dolt_add.go

@@ -48,22 +48,28 @@ func doDoltAdd(ctx *sql.Context, args []string) (int, error) {
 		return 1, err
 	}
 
-	apr, err := cli.CreateAddArgParser().Parse(args)
+	apr, err := cli.CreateAddArgParser(true).Parse(args)
 	if err != nil {
 		return 1, err
 	}
 
+	targetBranch, branchSpecified := apr.GetValue(cli.BranchParam)
+	if branchSpecified {
+		// Use revision-qualified database name for the target branch. This will enable you to add
+		// to branches other than the current branch.
+		dbName = fmt.Sprintf("%s/%s", dbName, targetBranch)
+	}
+
 	allFlag := apr.Contains(cli.AllFlag)
 
 	dSess := dsess.DSessFromSess(ctx.Session)
 	roots, ok := dSess.GetRoots(ctx, dbName)
+	if !ok {
+		return 1, fmt.Errorf("Could not load database %s", dbName)
+	}
 	if apr.NArg() == 0 && !allFlag {
 		return 1, fmt.Errorf("Nothing specified, nothing added. Maybe you wanted to say 'dolt add .'?")
 	} else if allFlag || apr.NArg() == 1 && apr.Arg(0) == "." {
-		if !ok {
-			return 1, fmt.Errorf("db session not found")
-		}
-
 		roots, err = actions.StageAllTables(ctx, roots, !apr.Contains(cli.ForceFlag))
 		if err != nil {
 			return 1, err