Introduce "agents"

An agent is currently a name given to a system prompt and a set of
tools which the agent has access to.

This resolves the previous issue of the set of configured tools being
available in *all* contexts, which wasn't always desired. Tools are now
only available when an agent is explicitly requested using the
`-a/--agent` flag.

Agents are expected to be expanded on: the concept of task-specilized
agents (e.g. coding), the ability to define a set of files an agent
should always have access to for RAG purposes, etc.

Other changes:

- Removes the "tools" top-level config structure (though this is expected
to come back along with the abillity to define custom tools).

- Renamed `pkg/agent` to `pkg/agents`

pkg/agents/tools.go

@@ -0,0 +1,48 @@
+package agents
+
+import (
+	"fmt"
+
+	"git.mlow.ca/mlow/lmcli/pkg/agents/toolbox"
+	"git.mlow.ca/mlow/lmcli/pkg/api"
+)
+
+var AvailableTools map[string]api.ToolSpec = map[string]api.ToolSpec{
+	"dir_tree":           toolbox.DirTreeTool,
+	"read_dir":           toolbox.ReadDirTool,
+	"read_file":          toolbox.ReadFileTool,
+	"write_file":         toolbox.WriteFileTool,
+	"file_insert_lines":  toolbox.FileInsertLinesTool,
+	"file_replace_lines": toolbox.FileReplaceLinesTool,
+}
+
+func ExecuteToolCalls(calls []api.ToolCall, available []api.ToolSpec) ([]api.ToolResult, error) {
+	var toolResults []api.ToolResult
+	for _, call := range calls {
+		var tool *api.ToolSpec
+		for i := range available {
+			if available[i].Name == call.Name {
+				tool = &available[i]
+				break
+			}
+		}
+		if tool == nil {
+			return nil, fmt.Errorf("Requested tool '%s' is not available. Hallucination?", call.Name)
+		}
+
+		// Execute the tool
+		result, err := tool.Impl(tool, call.Parameters)
+		if err != nil {
+			return nil, fmt.Errorf("Tool '%s' error: %v\n", call.Name, err)
+		}
+
+		toolResult := api.ToolResult{
+			ToolCallID: call.ID,
+			ToolName:   call.Name,
+			Result:     result,
+		}
+
+		toolResults = append(toolResults, toolResult)
+	}
+	return toolResults, nil
+}