1// Package core implements the agent loop, tool runtime, and session
2// persistence. It is provider-agnostic: it talks to an LLM only through
3// the provider.Client interface.
4package core
5
6import (
7 "context"
8 "encoding/json"
9 "fmt"
10 "sort"
11
12 "github.com/bnema/zut/packages/provider"
13)
14
15// Tool is a capability the agent can invoke.
16type Tool interface {
17 // Name is the unique tool id shown to the LLM.
18 Name() string
19 // Description is a one-line summary shown to the LLM.
20 Description() string
21 // Schema is a JSON Schema object for Execute's args.
22 Schema() json.RawMessage
23 // Execute runs the tool. progress may be called any number of times
24 // with partial textual output (for UIs); it is not sent to the LLM.
25 Execute(ctx context.Context, args json.RawMessage, progress func(string)) (ToolResult, error)
26}
27
28// ToolPreviewer is optionally implemented by tools that can describe their
29// exact effect without applying it. Confirmation UIs use the preview before
30// allowing a side-effecting call to proceed.
31type ToolPreviewer interface {
32 Preview(ctx context.Context, args json.RawMessage) (ToolResult, error)
33}
34
35// ToolResult is the outcome of Tool.Execute.
36type ToolResult struct {
37 // Content is sent back to the LLM (text and/or images).
38 Content []provider.Content
39 // IsError marks this result as an error to the LLM.
40 IsError bool
41 // ActivateTools names previously deferred tools that become available
42 // after this result. Unknown names are ignored by the agent.
43 ActivateTools []string
44 // Details is arbitrary data for UIs and logs; not sent to the LLM.
45 Details any
46 // Timing is populated by the core invocation boundary. It is also copied
47 // to the persisted/provider-facing tool-result block, where it remains
48 // optional for compatibility with older sessions.
49 Timing *provider.ToolTiming
50}
51
52// Registry is a name->Tool map.
53type Registry map[string]Tool
54
55// NewRegistry builds a Registry from a list of tools.
56func NewRegistry(tools ...Tool) Registry {
57 r := Registry{}
58 for _, t := range tools {
59 r[t.Name()] = t
60 }
61 return r
62}
63
64// Specs returns the tool definitions to advertise to the LLM.
65// Sorted by tool name so the order is stable across requests. This
66// is load-bearing for provider-side prompt caching: providers
67// prefix-match tool definitions, and Go's map iteration order is
68// randomized per call, which would otherwise bust the cache every
69// single turn.
70func (r Registry) Specs() []provider.Tool {
71 names := make([]string, 0, len(r))
72 for name := range r {
73 names = append(names, name)
74 }
75 sort.Strings(names)
76 out := make([]provider.Tool, 0, len(r))
77 for _, name := range names {
78 t := r[name]
79 deferred := false
80 if d, ok := t.(interface{ Deferred() bool }); ok {
81 deferred = d.Deferred()
82 }
83 out = append(out, provider.Tool{
84 Name: t.Name(),
85 Description: t.Description(),
86 Schema: t.Schema(),
87 Deferred: deferred,
88 })
89 }
90 return out
91}
92
93// Get looks up a tool by name.
94func (r Registry) Get(name string) (Tool, error) {
95 t, ok := r[name]
96 if !ok {
97 return nil, fmt.Errorf("unknown tool %q", name)
98 }
99 return t, nil
100}