chore: sync from fn-registry agent

tool_uses.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/mark3labs/mcp-go/mcp"
+)
+
+type usesArgs struct {
+	ID string `json:"id"`
+}
+
+func usesTool() mcp.Tool {
+	return mcp.NewTool("fn_uses",
+		mcp.WithDescription("Return the dependency edges for a function or type: which functions/types it uses (forward) and which functions consume it (reverse). Reverse lookup uses LIKE on uses_functions/uses_types JSON, so it's O(N) over the table — fast on registry.db (~1k rows)."),
+		mcp.WithString("id",
+			mcp.Required(),
+			mcp.Description("Registry ID."),
+		),
+	)
+}
+
+func (d *deps) handleUses(ctx context.Context, _ mcp.CallToolRequest, args usesArgs) (*mcp.CallToolResult, error) {
+	if args.ID == "" {
+		return mcp.NewToolResultError("id is required"), nil
+	}
+
+	out := map[string]any{"id": args.ID}
+	if f, err := d.db.GetFunction(args.ID); err == nil {
+		out["entity"] = "function"
+		out["uses_functions"] = f.UsesFunctions
+		out["uses_types"] = f.UsesTypes
+	} else if t, err := d.db.GetType(args.ID); err == nil {
+		out["entity"] = "type"
+		out["uses_types"] = t.UsesTypes
+	} else {
+		return mcp.NewToolResultError("id not found: " + args.ID), nil
+	}
+
+	conn := d.db.Conn()
+	pattern := "%\"" + args.ID + "\"%"
+	rows, err := conn.Query(`SELECT id FROM functions WHERE uses_functions LIKE ? OR uses_types LIKE ? ORDER BY id`, pattern, pattern)
+	if err != nil {
+		return mcp.NewToolResultError("reverse lookup: " + err.Error()), nil
+	}
+	defer rows.Close()
+	var consumers []string
+	for rows.Next() {
+		var id string
+		if err := rows.Scan(&id); err != nil {
+			return mcp.NewToolResultError("scan reverse: " + err.Error()), nil
+		}
+		consumers = append(consumers, id)
+	}
+	out["consumed_by"] = consumers
+
+	// Apps that declare the id in uses_functions (the apps table also stores the JSON list).
+	rows, err = conn.Query(`SELECT id FROM apps WHERE uses_functions LIKE ? ORDER BY id`, pattern)
+	if err == nil {
+		defer rows.Close()
+		var apps []string
+		for rows.Next() {
+			var id string
+			if err := rows.Scan(&id); err == nil {
+				apps = append(apps, id)
+			}
+		}
+		out["consumed_by_apps"] = apps
+	}
+
+	b, _ := json.MarshalIndent(out, "", "  ")
+	return mcp.NewToolResultText(string(b)), nil
+}