forked from bots-garden/ori
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 1 | // Package bridge relays events between the ACP agent session and the |
| 2 | // browsers connected over WebSocket. | |
| 3 | // | |
| 4 | // It is the meeting point of two asynchronous worlds: the agent streams | |
| 5 | // updates and blocks on permission requests; browsers connect, disconnect and | |
| 6 | // answer at human speed. The bridge broadcasts agent events to every client, | |
| 7 | // replays the session history to late joiners, and routes each permission | |
| 8 | // decision back to the exact request waiting for it. | |
| 9 | package bridge | |
| 10 | ||
| 11 | import ( | |
| 12 | "context" | |
| 13 | "encoding/json" | |
| 14 | "fmt" | |
| 15 | "log/slog" | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 16 | "path/filepath" |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 17 | "strconv" |
| 18 | "sync" | |
| 19 | ||
| 20 | acp "github.com/coder/acp-go-sdk" | |
| 21 | ) | |
| 22 | ||
| 23 | // Prompter is the slice of the agent session the bridge drives. It is | |
| 24 | // satisfied by *agent.Session and by test fakes. | |
| 25 | type Prompter interface { | |
| 26 | ID() string | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 27 | Prompt(ctx context.Context, blocks []acp.ContentBlock) (acp.StopReason, error) |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 28 | Cancel(ctx context.Context) error |
| 29 | } | |
| 30 | ||
| 31 | // maxHistory bounds the number of events replayed to late-joining clients; | |
| 32 | // beyond it the oldest events are dropped (the live broadcast is unaffected). | |
| 33 | const maxHistory = 4096 | |
| 34 | ||
| 35 | // clientBuffer is each subscriber's outgoing queue; a client too slow to | |
| 36 | // drain it is disconnected rather than allowed to stall the whole bridge. | |
| 37 | const clientBuffer = 256 | |
| 38 | ||
| 39 | type permissionDecision struct { | |
| 40 | optionId string | |
| 41 | cancelled bool | |
| 42 | } | |
| 43 | ||
| 44 | // Bridge broadcasts agent events to WebSocket clients and routes their | |
| 45 | // responses back to the agent. The zero value is not usable; call New. | |
| 46 | // | |
| 47 | // Example: | |
| 48 | // | |
| 49 | // b := bridge.New(slog.Default()) | |
| 50 | // session, _ := agent.Start(ctx, agent.Options{Handler: b, ...}) | |
| 51 | // b.SetSession(session) | |
| 52 | // http.Handle("GET /ws", b.WebSocketHandler()) | |
| 53 | type Bridge struct { | |
| 54 | logger *slog.Logger | |
| 55 | ||
| 56 | mu sync.Mutex | |
| 57 | session Prompter | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 58 | root string |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 59 | subscribers map[chan []byte]struct{} |
| 60 | history [][]byte | |
| 61 | turnActive bool | |
| 62 | nextRequest int | |
| 63 | pendingPerms map[string]chan permissionDecision | |
| 64 | // pendingRequests keeps the encoded permission_request events so they | |
| 65 | // can be replayed to clients that connect while a request is open. | |
| 66 | pendingRequests map[string][]byte | |
| 67 | } | |
| 68 | ||
| 69 | // New creates an empty bridge; attach the agent session with SetSession. | |
| 70 | func New(logger *slog.Logger) *Bridge { | |
| 71 | if logger == nil { | |
| 72 | logger = slog.Default() | |
| 73 | } | |
| 74 | return &Bridge{ | |
| 75 | logger: logger, | |
| 76 | subscribers: make(map[chan []byte]struct{}), | |
| 77 | pendingPerms: make(map[string]chan permissionDecision), | |
| 78 | pendingRequests: make(map[string][]byte), | |
| 79 | } | |
| 80 | } | |
| 81 | ||
| 82 | // SetSession attaches the agent session the bridge drives. It must be called | |
| 83 | // before the first client message arrives. | |
| 84 | func (b *Bridge) SetSession(session Prompter) { | |
| 85 | b.mu.Lock() | |
| 86 | defer b.mu.Unlock() | |
| 87 | b.session = session | |
| 88 | } | |
| 89 | ||
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 90 | // SetWorkspaceRoot sets the directory relative attachment paths resolve |
| 91 | // against (the agent's cwd). Without it, relative paths are sent as given. | |
| 92 | func (b *Bridge) SetWorkspaceRoot(root string) { | |
| 93 | b.mu.Lock() | |
| 94 | defer b.mu.Unlock() | |
| 95 | b.root = root | |
| 96 | } | |
| 97 | ||
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 98 | // Subscribe registers a new client. It returns the client's event channel, |
| 99 | // the events to replay so the client catches up (history, then any pending | |
| 100 | // permission requests), and an unsubscribe function. | |
| 101 | func (b *Bridge) Subscribe() (events <-chan []byte, replay [][]byte, unsubscribe func()) { | |
| 102 | ch := make(chan []byte, clientBuffer) | |
| 103 | b.mu.Lock() | |
| 104 | defer b.mu.Unlock() | |
| 105 | ||
| 106 | b.subscribers[ch] = struct{}{} | |
| 107 | ||
| 108 | sessionId := "" | |
| 109 | if b.session != nil { | |
| 110 | sessionId = b.session.ID() | |
| 111 | } | |
| 112 | replay = append(replay, encode(Outgoing{Type: OutgoingHello, SessionId: sessionId, TurnActive: b.turnActive})) | |
| 113 | replay = append(replay, b.history...) | |
| 114 | for _, raw := range b.pendingRequests { | |
| 115 | replay = append(replay, raw) | |
| 116 | } | |
| 117 | ||
| 118 | return ch, replay, func() { | |
| 119 | b.mu.Lock() | |
| 120 | defer b.mu.Unlock() | |
| 121 | if _, ok := b.subscribers[ch]; ok { | |
| 122 | delete(b.subscribers, ch) | |
| 123 | close(ch) | |
| 124 | } | |
| 125 | } | |
| 126 | } | |
| 127 | ||
| 128 | // HandleIncoming processes one message from a client. Errors are reported to | |
| 129 | // the clients as OutgoingError events, never returned: a malformed message | |
| 130 | // from one browser must not tear down the connection handling. | |
| 131 | func (b *Bridge) HandleIncoming(ctx context.Context, raw []byte) { | |
| 132 | var msg Incoming | |
| 133 | if err := json.Unmarshal(raw, &msg); err != nil { | |
| 134 | b.broadcast(encode(Outgoing{Type: OutgoingError, Message: "malformed message: " + err.Error()}), false) | |
| 135 | return | |
| 136 | } | |
| 137 | ||
| 138 | switch msg.Type { | |
| 139 | case IncomingPrompt: | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 140 | b.startTurn(msg.Text, msg.Attachments) |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 141 | case IncomingCancel: |
| 142 | b.cancelTurn(ctx) | |
| 143 | case IncomingPermissionResponse: | |
| 144 | b.resolvePermission(msg) | |
| 145 | default: | |
| 146 | b.broadcast(encode(Outgoing{Type: OutgoingError, Message: fmt.Sprintf("unknown message type %q", msg.Type)}), false) | |
| 147 | } | |
| 148 | } | |
| 149 | ||
| 150 | // startTurn launches a prompt turn in the background; updates stream through | |
| 151 | // HandleSessionUpdate while it runs. | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 152 | func (b *Bridge) startTurn(text string, attachments []Attachment) { |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 153 | b.mu.Lock() |
| 154 | session := b.session | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 155 | root := b.root |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 156 | if session == nil { |
| 157 | b.mu.Unlock() | |
| 158 | b.broadcast(encode(Outgoing{Type: OutgoingError, Message: "no agent session"}), false) | |
| 159 | return | |
| 160 | } | |
| 161 | if b.turnActive { | |
| 162 | b.mu.Unlock() | |
| 163 | b.broadcast(encode(Outgoing{Type: OutgoingError, Message: "a turn is already running"}), false) | |
| 164 | return | |
| 165 | } | |
| 166 | b.turnActive = true | |
| 167 | b.mu.Unlock() | |
| 168 | ||
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 169 | b.broadcast(encode(Outgoing{Type: OutgoingUserMessage, Text: text, Attachments: attachments}), true) |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 170 | b.broadcast(encode(Outgoing{Type: OutgoingTurnStarted}), true) |
| 171 | ||
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 172 | blocks := promptBlocks(text, attachments, root) |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 173 | go func() { |
| 174 | // The turn outlives the WebSocket message that started it, so it | |
| 175 | // runs under its own context, ended by session/cancel only. | |
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 176 | stop, err := session.Prompt(context.Background(), blocks) |
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 177 | |
| 178 | b.mu.Lock() | |
| 179 | b.turnActive = false | |
| 180 | b.mu.Unlock() | |
| 181 | ||
| 182 | if err != nil { | |
| 183 | b.logger.Error("prompt failed", "error", err) | |
| 184 | b.broadcast(encode(Outgoing{Type: OutgoingError, Message: "prompt failed: " + err.Error()}), true) | |
| 185 | b.broadcast(encode(Outgoing{Type: OutgoingTurnEnded, StopReason: string(acp.StopReasonRefusal)}), true) | |
| 186 | return | |
| 187 | } | |
| 188 | b.broadcast(encode(Outgoing{Type: OutgoingTurnEnded, StopReason: string(stop)}), true) | |
| 189 | }() | |
| 190 | } | |
| 191 | ||
| ✨ Workspace panel, selectors, previews, desktop app, sandbox template, resizable file tree, light/dark theme | 192 | // promptBlocks builds the ACP prompt: the text first, then one resource_link |
| 193 | // per attachment (file:// URI, named after the mention), which every ACP | |
| 194 | // agent must accept. | |
| 195 | // | |
| 196 | // Example: | |
| 197 | // | |
| 198 | // promptBlocks("Explain @src/main.go", []Attachment{{Path: "src/main.go"}}, "/work") | |
| 199 | // // [text "Explain @src/main.go", resource_link name=src/main.go uri=file:///work/src/main.go] | |
| 200 | func promptBlocks(text string, attachments []Attachment, root string) []acp.ContentBlock { | |
| 201 | blocks := []acp.ContentBlock{acp.TextBlock(text)} | |
| 202 | for _, attachment := range attachments { | |
| 203 | if attachment.Path == "" { | |
| 204 | continue | |
| 205 | } | |
| 206 | path := attachment.Path | |
| 207 | if !filepath.IsAbs(path) && root != "" { | |
| 208 | path = filepath.Join(root, path) | |
| 209 | } | |
| 210 | name := attachment.Name | |
| 211 | if name == "" { | |
| 212 | name = attachment.Path | |
| 213 | } | |
| 214 | blocks = append(blocks, acp.ResourceLinkBlock(name, "file://"+filepath.ToSlash(path))) | |
| 215 | } | |
| 216 | return blocks | |
| 217 | } | |
| 218 | ||
| ✨ Introduce new feature(s): ACP web client — Go backend (agent, bridge, httpserver, mockagent) + React SPA (Zed-like agent panel), tests, quality gate PASS | 219 | func (b *Bridge) cancelTurn(ctx context.Context) { |
| 220 | b.mu.Lock() | |
| 221 | session := b.session | |
| 222 | b.mu.Unlock() | |
| 223 | if session == nil { | |
| 224 | return | |
| 225 | } | |
| 226 | if err := session.Cancel(ctx); err != nil { | |
| 227 | b.logger.Error("cancel failed", "error", err) | |
| 228 | b.broadcast(encode(Outgoing{Type: OutgoingError, Message: "cancel failed: " + err.Error()}), false) | |
| 229 | } | |
| 230 | } | |
| 231 | ||
| 232 | func (b *Bridge) resolvePermission(msg Incoming) { | |
| 233 | b.mu.Lock() | |
| 234 | waiting, ok := b.pendingPerms[msg.RequestId] | |
| 235 | if ok { | |
| 236 | delete(b.pendingPerms, msg.RequestId) | |
| 237 | delete(b.pendingRequests, msg.RequestId) | |
| 238 | } | |
| 239 | b.mu.Unlock() | |
| 240 | if !ok { | |
| 241 | // Either already answered by another client or unknown: ignore. | |
| 242 | return | |
| 243 | } | |
| 244 | waiting <- permissionDecision{optionId: msg.OptionId, cancelled: msg.Cancelled} | |
| 245 | b.broadcast(encode(Outgoing{Type: OutgoingPermissionResolved, RequestId: msg.RequestId}), true) | |
| 246 | } | |
| 247 | ||
| 248 | // HandleSessionUpdate implements agent.Handler: every ACP update is relayed | |
| 249 | // verbatim to the clients and recorded for replay. | |
| 250 | func (b *Bridge) HandleSessionUpdate(_ context.Context, notification acp.SessionNotification) { | |
| 251 | update, err := json.Marshal(notification.Update) | |
| 252 | if err != nil { | |
| 253 | b.logger.Error("marshal session update", "error", err) | |
| 254 | return | |
| 255 | } | |
| 256 | b.broadcast(encode(Outgoing{Type: OutgoingSessionUpdate, Update: update}), true) | |
| 257 | } | |
| 258 | ||
| 259 | // HandlePermissionRequest implements agent.Handler: the request is broadcast | |
| 260 | // to the clients and the call blocks until one of them answers or the agent | |
| 261 | // cancels the turn. | |
| 262 | func (b *Bridge) HandlePermissionRequest(ctx context.Context, request acp.RequestPermissionRequest) (acp.RequestPermissionResponse, error) { | |
| 263 | rawRequest, err := json.Marshal(request) | |
| 264 | if err != nil { | |
| 265 | return acp.RequestPermissionResponse{}, fmt.Errorf("marshal permission request: %w", err) | |
| 266 | } | |
| 267 | ||
| 268 | decisionCh := make(chan permissionDecision, 1) | |
| 269 | b.mu.Lock() | |
| 270 | b.nextRequest++ | |
| 271 | requestId := "perm-" + strconv.Itoa(b.nextRequest) | |
| 272 | event := encode(Outgoing{Type: OutgoingPermissionRequest, RequestId: requestId, Request: rawRequest}) | |
| 273 | b.pendingPerms[requestId] = decisionCh | |
| 274 | b.pendingRequests[requestId] = event | |
| 275 | b.mu.Unlock() | |
| 276 | ||
| 277 | b.broadcast(event, false) | |
| 278 | ||
| 279 | select { | |
| 280 | case decision := <-decisionCh: | |
| 281 | if decision.cancelled { | |
| 282 | return acp.RequestPermissionResponse{Outcome: acp.NewRequestPermissionOutcomeCancelled()}, nil | |
| 283 | } | |
| 284 | return acp.RequestPermissionResponse{Outcome: acp.NewRequestPermissionOutcomeSelected(acp.PermissionOptionId(decision.optionId))}, nil | |
| 285 | case <-ctx.Done(): | |
| 286 | // The agent cancelled the turn (or disconnected) while waiting. | |
| 287 | b.mu.Lock() | |
| 288 | delete(b.pendingPerms, requestId) | |
| 289 | delete(b.pendingRequests, requestId) | |
| 290 | b.mu.Unlock() | |
| 291 | b.broadcast(encode(Outgoing{Type: OutgoingPermissionResolved, RequestId: requestId}), true) | |
| 292 | return acp.RequestPermissionResponse{Outcome: acp.NewRequestPermissionOutcomeCancelled()}, nil | |
| 293 | } | |
| 294 | } | |
| 295 | ||
| 296 | // broadcast sends an event to every connected client, disconnecting any | |
| 297 | // client whose buffer is full. With record=true the event also joins the | |
| 298 | // replay history. | |
| 299 | func (b *Bridge) broadcast(event []byte, record bool) { | |
| 300 | b.mu.Lock() | |
| 301 | defer b.mu.Unlock() | |
| 302 | ||
| 303 | if record { | |
| 304 | b.history = append(b.history, event) | |
| 305 | if len(b.history) > maxHistory { | |
| 306 | b.history = b.history[len(b.history)-maxHistory:] | |
| 307 | } | |
| 308 | } | |
| 309 | ||
| 310 | for ch := range b.subscribers { | |
| 311 | select { | |
| 312 | case ch <- event: | |
| 313 | default: | |
| 314 | // The client stopped draining; drop it instead of blocking | |
| 315 | // the agent's event stream. | |
| 316 | delete(b.subscribers, ch) | |
| 317 | close(ch) | |
| 318 | b.logger.Warn("dropped a slow websocket client") | |
| 319 | } | |
| 320 | } | |
| 321 | } |