fix: resolve usernames to bech32 addresses in assignees

create_pull_request and update_issue (add/remove assignees) now accept
usernames (e.g. "htrap") and resolve them to bech32 addresses via the
chain's User query. Addresses starting with "gitopia1" are passed through.

Fixes Gitopia/gitopia-mcp-server#3

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hTrap

internal/gitopia/client.go

@@ -170,6 +170,25 @@ func (c *Client) GetUserByAddress(ctx context.Context, address string) (*User, e
 	}, nil
 }
 
+// GetUserByUsername queries a user by username and returns their address.
+func (c *Client) GetUserByUsername(ctx context.Context, username string) (*User, error) {
+	q := gitopiatypes.NewQueryClient(c.conn)
+	resp, err := q.User(ctx, &gitopiatypes.QueryGetUserRequest{
+		Id: username,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to query user '%s': %w", username, err)
+	}
+	if resp.User == nil {
+		return nil, fmt.Errorf("user not found: %s", username)
+	}
+	return &User{
+		ID:       strconv.FormatUint(resp.User.Id, 10),
+		Username: resp.User.Username,
+		Address:  resp.User.Creator,
+	}, nil
+}
+
 // GetUserDAOs queries DAOs that a user is a member of
 func (c *Client) GetUserDAOs(ctx context.Context, username string) ([]DAO, error) {
 	q := gitopiatypes.NewQueryClient(c.conn)

internal/handler/gitopia_handlers.go

@@ -13,6 +13,25 @@ import (
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 )
 
+// resolveAssignees converts a list of usernames or addresses to bech32 addresses.
+// If a value is already a bech32 address (starts with "gitopia1"), it's kept as-is.
+// Otherwise it's treated as a username and resolved via the chain.
+func (h *ToolHandler) resolveAssignees(ctx context.Context, assignees []string) ([]string, error) {
+	resolved := make([]string, 0, len(assignees))
+	for _, a := range assignees {
+		if strings.HasPrefix(a, "gitopia1") {
+			resolved = append(resolved, a)
+			continue
+		}
+		user, err := h.GClient.GetUserByUsername(ctx, a)
+		if err != nil {
+			return nil, fmt.Errorf("failed to resolve assignee '%s': %s", a, err)
+		}
+		resolved = append(resolved, user.Address)
+	}
+	return resolved, nil
+}
+
 // ---- Gitopia API Handlers ----
 
 type ListReposParams struct {
@@ -366,12 +385,20 @@ func (h *ToolHandler) UpdateIssue(
 	}
 
 	if len(p.AddAssignees) > 0 {
-		msgs = append(msgs, gitopiatypes.NewMsgAddIssueAssignees(w.Address(), repo.Id, p.IssueIid, p.AddAssignees))
+		resolved, resolveErr := h.resolveAssignees(ctx, p.AddAssignees)
+		if resolveErr != nil {
+			return toolErrorf(ErrValidation, "%s", resolveErr)
+		}
+		msgs = append(msgs, gitopiatypes.NewMsgAddIssueAssignees(w.Address(), repo.Id, p.IssueIid, resolved))
 		actions = append(actions, fmt.Sprintf("added %d assignees", len(p.AddAssignees)))
 	}
 
 	if len(p.RemoveAssignees) > 0 {
-		msgs = append(msgs, gitopiatypes.NewMsgRemoveIssueAssignees(w.Address(), repo.Id, p.IssueIid, p.RemoveAssignees))
+		resolved, resolveErr := h.resolveAssignees(ctx, p.RemoveAssignees)
+		if resolveErr != nil {
+			return toolErrorf(ErrValidation, "%s", resolveErr)
+		}
+		msgs = append(msgs, gitopiatypes.NewMsgRemoveIssueAssignees(w.Address(), repo.Id, p.IssueIid, resolved))
 		actions = append(actions, fmt.Sprintf("removed %d assignees", len(p.RemoveAssignees)))
 	}
 
@@ -651,9 +678,17 @@ func (h *ToolHandler) CreatePullRequest(
 	if err != nil {
 		return toolErrorf(ErrAuthFailed, "Authentication failed: %s", err)
 	}
+	// Resolve usernames to bech32 addresses if needed
+	assignees := p.Assignees
+	if len(assignees) > 0 {
+		assignees, err = h.resolveAssignees(ctx, assignees)
+		if err != nil {
+			return toolErrorf(ErrValidation, "%s", err)
+		}
+	}
 	start := time.Now()
 	prNumber, err := retryOnSequenceMismatch(func() (int, error) {
-		return h.GClient.CreatePullRequest(ctx, w, p.Owner, p.Name, p.Title, p.Description, p.HeadBranch, p.BaseBranch, p.Assignees, p.Labels, p.IssueIids)
+		return h.GClient.CreatePullRequest(ctx, w, p.Owner, p.Name, p.Title, p.Description, p.HeadBranch, p.BaseBranch, assignees, p.Labels, p.IssueIids)
 	})
 	AuditLog("create_pull_request", w.Address(), err == nil, time.Since(start), "")
 	if err != nil {