| 1 | // Package extension is the Go SDK for Reasonix extension sidecars speaking |
| 2 | // Extension Protocol v2 over stdio. An extension is a separate process: the |
| 3 | // Reasonix host launches it, sends extension/initialize first, drives |
| 4 | // intercepts, events, provider streams, and UI calls, and finally asks it to |
| 5 | // stop with extension/shutdown. |
| 6 | // |
| 7 | // The transport is strict JSON-RPC 2.0 framed as NDJSON (one object per |
| 8 | // line, integer request ids, params as JSON objects, frames capped at |
| 9 | // FrameBytes). The SDK owns the wire, the handshake barrier, and the |
| 10 | // shutdown sequence; the extension implements Handler and, optionally, |
| 11 | // interceptors, a Provider, and UI callbacks via Options. After Initialize |
| 12 | // completes, the SDK may invoke up to 32 callbacks concurrently; extensions |
| 13 | // must synchronize any mutable state shared by those callbacks. |
| 14 | // |
| 15 | // After Serve returns nil from an orderly extension/shutdown the process |
| 16 | // should exit with code 0; the host reaps it by that exit status. |
| 17 | // |
| 18 | // Protocol reference: docs/EXTENSION_PROTOCOL.generated.md and |
| 19 | // internal/extension/protocol/schema.generated.json in the Reasonix |
| 20 | // repository. |
| 21 | package extension |
| 22 | |
| 23 | import ( |
| 24 | "bytes" |
| 25 | "context" |
| 26 | "crypto/sha256" |
| 27 | "encoding/base64" |
| 28 | "encoding/hex" |
| 29 | "encoding/json" |
| 30 | "errors" |
| 31 | "fmt" |
| 32 | "io" |
| 33 | "log" |
| 34 | "os" |
| 35 | "strconv" |
| 36 | "strings" |
| 37 | "sync" |
| 38 | "time" |
| 39 | ) |
| 40 | |
| 41 | // Public callback types |
| 42 | |
| 43 | // Handler is the one mandatory extension hook. Initialize is called once and |
| 44 | // completes before any other callback. Return the sidecar's declaration |
| 45 | // (name, version, subscriptions, replaces, providers, UI actions) — the host |
| 46 | // rejects anything beyond the installed manifest. |
| 47 | type Handler interface { |
| 48 | Initialize(ctx context.Context, p InitializeParams) (*InitializeResult, error) |
| 49 | } |
| 50 | |
| 51 | // InterceptorFunc rules on one intercepted event. payload is the event |
| 52 | // payload as raw JSON; content-ref externalized payloads are rehydrated |
| 53 | // before the call. Return one of Continue, Block, Replace, Allow, or Deny; a |
| 54 | // nil result is Continue. A non-nil error answers the intercept with the |
| 55 | // frozen internal error and the host proceeds with its default behavior. |
| 56 | type InterceptorFunc func(ctx context.Context, event string, payload json.RawMessage) (*InterceptResult, error) |
| 57 | |
| 58 | // Provider brokers extension-hosted model providers. The extension holds the |
| 59 | // credentials; only the credential-free DTOs cross the wire. |
| 60 | type Provider interface { |
| 61 | // Catalog returns the extension's full provider catalog. It may run |
| 62 | // concurrently with other callbacks. |
| 63 | Catalog(ctx context.Context) ([]ProviderDescriptor, error) |
| 64 | // Stream opens one stream and returns its chunk channel. Stream must |
| 65 | // return promptly; produce chunks in the background. The SDK numbers |
| 66 | // chunks 1,2,3,… (from the host's SeqBase) and ends the stream with |
| 67 | // exactly one stream/end: close the channel for a clean end, send an |
| 68 | // ErrorChunk (or a chunk with Type ChunkError) to fail the stream with |
| 69 | // end.error, and stop producing when ctx is cancelled (host cancel or |
| 70 | // shutdown) — the SDK then ends the stream interrupted. Multiple Stream |
| 71 | // calls may run concurrently. |
| 72 | Stream(ctx context.Context, req StreamRequest) (<-chan StreamChunk, error) |
| 73 | } |
| 74 | |
| 75 | // StreamRequest is one opened provider stream. |
| 76 | type StreamRequest struct { |
| 77 | StreamID string |
| 78 | ProviderRef string |
| 79 | Model string |
| 80 | Effort string |
| 81 | Request ProviderRequest |
| 82 | } |
| 83 | |
| 84 | // StreamChunk is one chunk a Provider produces; it is exactly the wire |
| 85 | // ProviderChunk. Build them with TextChunk, ReasoningChunk, UsageChunk, |
| 86 | // DoneChunk, and ErrorChunk. |
| 87 | type StreamChunk = ProviderChunk |
| 88 | |
| 89 | // TextChunk is one assistant text delta. |
| 90 | func TextChunk(text string) StreamChunk { return StreamChunk{Type: ChunkText, Text: text} } |
| 91 | |
| 92 | // ReasoningChunk is one reasoning delta with its optional signature. |
| 93 | func ReasoningChunk(text, signature string) StreamChunk { |
| 94 | return StreamChunk{Type: ChunkReasoning, Text: text, Signature: signature} |
| 95 | } |
| 96 | |
| 97 | // UsageChunk carries final token accounting. |
| 98 | func UsageChunk(usage ProviderUsage) StreamChunk { |
| 99 | return StreamChunk{Type: ChunkUsage, Usage: &usage} |
| 100 | } |
| 101 | |
| 102 | // DoneChunk marks the logical end of the assistant turn. The stream itself |
| 103 | // ends when the channel closes. |
| 104 | func DoneChunk() StreamChunk { return StreamChunk{Type: ChunkDone} } |
| 105 | |
| 106 | // ErrorChunk fails the stream. The SDK ends it with stream/end.error set to |
| 107 | // the chunk's message instead of forwarding the chunk. Keep the message |
| 108 | // generic: it crosses the wire and must never contain credentials, endpoints, |
| 109 | // or response bodies. |
| 110 | func ErrorChunk(message string) StreamChunk { |
| 111 | if strings.TrimSpace(message) == "" { |
| 112 | message = frozenErrorSpecs[ErrProviderFailed].Message |
| 113 | } |
| 114 | return StreamChunk{Type: ChunkError, Error: &ProviderError{Code: ProviderFailed, Message: message}} |
| 115 | } |
| 116 | |
| 117 | // UIHandler carries the extension's UI callbacks. A nil func makes the |
| 118 | // matching method answer unknown_method. |
| 119 | type UIHandler struct { |
| 120 | // Action runs one handshake-declared action. A non-nil error answers |
| 121 | // with {accepted:false, message}. |
| 122 | Action func(ctx context.Context, actionID string, args map[string]string) error |
| 123 | // Submit consumes one published form surface's values. A non-nil error |
| 124 | // answers with {accepted:false} and is logged. |
| 125 | Submit func(ctx context.Context, surfaceID string, values map[string]any) error |
| 126 | } |
| 127 | |
| 128 | // Options configures Serve. Stdin/Stdout default to os.Stdin/os.Stdout. After |
| 129 | // Initialize, callback fields and Provider methods may be invoked concurrently |
| 130 | // (up to 32 inbound handlers); protect shared mutable maps, slices, counters, |
| 131 | // and clients with synchronization appropriate to the extension. |
| 132 | type Options struct { |
| 133 | Stdin io.Reader |
| 134 | Stdout io.Writer |
| 135 | // Name and Version fill InitializeResult when the Handler leaves them |
| 136 | // empty. |
| 137 | Name string |
| 138 | Version string |
| 139 | // Interceptors maps an event name ("session.start", …) to its ruling |
| 140 | // func; "*" is the wildcard fallback for events without an exact entry. |
| 141 | Interceptors map[string]InterceptorFunc |
| 142 | // Observer receives extension/event notifications. Events are |
| 143 | // fire-and-forget; the observer cannot change host behavior. |
| 144 | Observer func(ctx context.Context, event string, payload json.RawMessage) |
| 145 | // ResourcesChanged receives extension/resources/changed notifications. |
| 146 | ResourcesChanged func(ctx context.Context, paths []string) |
| 147 | // Provider serves extension/provider/*; nil answers those methods with |
| 148 | // unknown_method. |
| 149 | Provider Provider |
| 150 | // UI serves extension/ui/action and extension/ui/submit. |
| 151 | UI UIHandler |
| 152 | // Shutdown runs on extension/shutdown, bounded by the host's |
| 153 | // TimeoutMillis. After it returns (or times out) the SDK answers |
| 154 | // {accepted:true} and closes the transport; the process should then |
| 155 | // exit(0). |
| 156 | Shutdown func(ctx context.Context) |
| 157 | // Logger receives stderr diagnostics (protocol violations, dropped |
| 158 | // notifications, handler errors). Defaults to a stderr logger. |
| 159 | Logger *log.Logger |
| 160 | } |
| 161 | |
| 162 | // Sentinel errors |
| 163 | |
| 164 | // ErrNotReady reports an Extension → Host call made before the handshake |
| 165 | // barrier opened: the sidecar must not send requests or notifications before |
| 166 | // the host's extension/initialized notification. |
| 167 | var ErrNotReady = errors.New("extension: host connection is not initialized (wait for extension/initialized)") |
| 168 | |
| 169 | // ErrNoConnection reports a helper call (HostUI methods, ReadContentRef, |
| 170 | // ResolveExternalized) with a context that did not come from an SDK |
| 171 | // callback. |
| 172 | var ErrNoConnection = errors.New("extension: no host connection in context (use the context passed to an SDK callback)") |
| 173 | |
| 174 | // ErrUICancelled reports a host prompt the user dismissed. UIRequestResult |
| 175 | // distinguishes dismissal from an empty value set; the SDK surfaces it as |
| 176 | // this sentinel. |
| 177 | var ErrUICancelled = errors.New("extension: the user dismissed the prompt") |
| 178 | |
| 179 | // InterceptResult helpers |
| 180 | |
| 181 | // Continue lets the event proceed unchanged. |
| 182 | func Continue() *InterceptResult { return &InterceptResult{Decision: DecisionContinue} } |
| 183 | |
| 184 | // Block stops the event with a human-readable reason. |
| 185 | func Block(reason string) *InterceptResult { |
| 186 | return &InterceptResult{Decision: DecisionBlock, Reason: reason} |
| 187 | } |
| 188 | |
| 189 | // Replace substitutes the event payload. payload may be a json.RawMessage |
| 190 | // (used verbatim, must be valid JSON) or any marshalable value. The |
| 191 | // replacement travels inline; only the host can mint content refs, so a |
| 192 | // replacement must fit in one frame. |
| 193 | func Replace(payload any) (*InterceptResult, error) { |
| 194 | var raw json.RawMessage |
| 195 | switch value := payload.(type) { |
| 196 | case json.RawMessage: |
| 197 | raw = value |
| 198 | case []byte: |
| 199 | raw = value |
| 200 | default: |
| 201 | encoded, err := json.Marshal(payload) |
| 202 | if err != nil { |
| 203 | return nil, fmt.Errorf("extension: marshal replacement: %w", err) |
| 204 | } |
| 205 | raw = encoded |
| 206 | } |
| 207 | if !json.Valid(raw) { |
| 208 | return nil, errors.New("extension: replacement is not valid JSON") |
| 209 | } |
| 210 | return &InterceptResult{Decision: DecisionReplace, Replacement: raw}, nil |
| 211 | } |
| 212 | |
| 213 | // Allow grants a permission.decision intercept. |
| 214 | func Allow() *InterceptResult { return &InterceptResult{Decision: DecisionAllow} } |
| 215 | |
| 216 | // Deny refuses a permission.decision intercept with a reason. |
| 217 | func Deny(reason string) *InterceptResult { |
| 218 | return &InterceptResult{Decision: DecisionDeny, Reason: reason} |
| 219 | } |
| 220 | |
| 221 | // Serve |
| 222 | |
| 223 | type serverState uint8 |
| 224 | |
| 225 | const ( |
| 226 | stateNew serverState = iota |
| 227 | // stateHandshake is entered when extension/initialize arrives and held |
| 228 | // until the host's extension/initialized notification opens the barrier. |
| 229 | stateHandshake |
| 230 | stateReady |
| 231 | stateShutdown |
| 232 | ) |
| 233 | |
| 234 | type server struct { |
| 235 | conn *conn |
| 236 | handler Handler |
| 237 | opts Options |
| 238 | log *log.Logger |
| 239 | |
| 240 | mu sync.Mutex |
| 241 | state serverState |
| 242 | shutdownOnce sync.Once |
| 243 | |
| 244 | streamsMu sync.Mutex |
| 245 | streams map[string]*streamHandle |
| 246 | } |
| 247 | |
| 248 | type streamHandle struct { |
| 249 | cancel context.CancelFunc |
| 250 | done chan struct{} |
| 251 | } |
| 252 | |
| 253 | type serverContextKey struct{} |
| 254 | |
| 255 | func serverFrom(ctx context.Context) *server { |
| 256 | s, _ := ctx.Value(serverContextKey{}).(*server) |
| 257 | return s |
| 258 | } |
| 259 | |
| 260 | // Serve runs the extension sidecar lifecycle on Options.Stdin/Stdout until |
| 261 | // the host closes the transport, asks for shutdown, or fatally violates the |
| 262 | // protocol. It returns nil on a clean end (host EOF or an answered |
| 263 | // extension/shutdown) and a non-nil error otherwise; canceling ctx tears |
| 264 | // everything down and returns the ctx error. After an orderly shutdown the |
| 265 | // process should exit(0). |
| 266 | func Serve(ctx context.Context, h Handler, opts Options) error { |
| 267 | if h == nil { |
| 268 | return errors.New("extension: Serve requires a non-nil Handler") |
| 269 | } |
| 270 | stdin := opts.Stdin |
| 271 | if stdin == nil { |
| 272 | stdin = os.Stdin |
| 273 | } |
| 274 | stdout := opts.Stdout |
| 275 | if stdout == nil { |
| 276 | stdout = os.Stdout |
| 277 | } |
| 278 | logger := opts.Logger |
| 279 | if logger == nil { |
| 280 | logger = log.New(os.Stderr, "reasonix-extension: ", log.LstdFlags) |
| 281 | } |
| 282 | s := &server{ |
| 283 | handler: h, |
| 284 | opts: opts, |
| 285 | log: logger, |
| 286 | state: stateNew, |
| 287 | streams: make(map[string]*streamHandle), |
| 288 | } |
| 289 | c := newConn(stdin, stdout, logger) |
| 290 | s.conn = c |
| 291 | c.beforeRequest = s.gateRequest |
| 292 | c.beforeNotification = s.gateNotification |
| 293 | |
| 294 | c.reqH[MethodExtensionInitialize] = s.withConnRequest(s.handleInitialize) |
| 295 | c.reqH[MethodExtensionShutdown] = s.withConnRequest(s.handleShutdown) |
| 296 | c.reqH[MethodExtensionIntercept] = s.withConnRequest(s.handleIntercept) |
| 297 | c.reqH[MethodExtensionProviderCatalog] = s.withConnRequest(s.handleProviderCatalog) |
| 298 | c.reqH[MethodExtensionProviderStreamOpen] = s.withConnRequest(s.handleStreamOpen) |
| 299 | c.reqH[MethodExtensionProviderStreamCancel] = s.withConnRequest(s.handleStreamCancel) |
| 300 | c.reqH[MethodExtensionUIAction] = s.withConnRequest(s.handleUIAction) |
| 301 | c.reqH[MethodExtensionUISubmit] = s.withConnRequest(s.handleUISubmit) |
| 302 | c.notH[MethodExtensionInitialized] = s.withConnNotification(s.handleInitialized) |
| 303 | c.notH[MethodExtensionEvent] = s.withConnNotification(s.handleEvent) |
| 304 | c.notH[MethodExtensionResourcesChanged] = s.withConnNotification(s.handleResourcesChanged) |
| 305 | |
| 306 | return c.serve(ctx) |
| 307 | } |
| 308 | |
| 309 | // withConnRequest injects the server into handler contexts so HostUI, |
| 310 | // ReadContentRef, and ResolveExternalized can reach the transport. |
| 311 | func (s *server) withConnRequest(f requestHandler) requestHandler { |
| 312 | return func(ctx context.Context, raw json.RawMessage) (any, error) { |
| 313 | return f(context.WithValue(ctx, serverContextKey{}, s), raw) |
| 314 | } |
| 315 | } |
| 316 | |
| 317 | func (s *server) withConnNotification(f notificationHandler) notificationHandler { |
| 318 | return func(ctx context.Context, raw json.RawMessage) { |
| 319 | f(context.WithValue(ctx, serverContextKey{}, s), raw) |
| 320 | } |
| 321 | } |
| 322 | |
| 323 | // Handshake barrier |
| 324 | |
| 325 | // gateRequest runs on the read loop before dispatch: the host must open with |
| 326 | // extension/initialize, and until its extension/initialized notification |
| 327 | // arrives only the lifecycle methods are served. Everything else is answered |
| 328 | // with the frozen protocol_error. |
| 329 | func (s *server) gateRequest(method string) error { |
| 330 | s.mu.Lock() |
| 331 | defer s.mu.Unlock() |
| 332 | switch s.state { |
| 333 | case stateReady: |
| 334 | return nil |
| 335 | case stateNew: |
| 336 | switch method { |
| 337 | case MethodExtensionInitialize: |
| 338 | s.state = stateHandshake |
| 339 | return nil |
| 340 | case MethodExtensionShutdown: |
| 341 | return nil |
| 342 | } |
| 343 | case stateHandshake: |
| 344 | if method == MethodExtensionShutdown { |
| 345 | return nil |
| 346 | } |
| 347 | case stateShutdown: |
| 348 | // fall through to the error below |
| 349 | } |
| 350 | return &ProtocolError{ |
| 351 | Reason: ErrProtocolError, |
| 352 | Message: fmt.Sprintf("extension protocol violation: host sent request %q before the handshake completed", method), |
| 353 | } |
| 354 | } |
| 355 | |
| 356 | // gateNotification applies the same barrier to notifications; violations are |
| 357 | // dropped (JSON-RPC notifications carry no response). |
| 358 | func (s *server) gateNotification(method string) error { |
| 359 | s.mu.Lock() |
| 360 | defer s.mu.Unlock() |
| 361 | switch s.state { |
| 362 | case stateReady: |
| 363 | return nil |
| 364 | case stateHandshake: |
| 365 | if method == MethodExtensionInitialized { |
| 366 | s.state = stateReady |
| 367 | return nil |
| 368 | } |
| 369 | } |
| 370 | return fmt.Errorf("extension: dropping notification %q before the handshake completed", method) |
| 371 | } |
| 372 | |
| 373 | // checkReady gates Extension → Host calls on the opened barrier. |
| 374 | func (s *server) checkReady() error { |
| 375 | s.mu.Lock() |
| 376 | defer s.mu.Unlock() |
| 377 | if s.state != stateReady { |
| 378 | return ErrNotReady |
| 379 | } |
| 380 | return nil |
| 381 | } |
| 382 | |
| 383 | // Lifecycle handlers |
| 384 | |
| 385 | // fatalError marks handler failures that must end the connection after the |
| 386 | // error response is written (a failed handshake leaves nothing to serve). |
| 387 | type fatalError struct{ err error } |
| 388 | |
| 389 | func (e *fatalError) Error() string { return e.err.Error() } |
| 390 | func (e *fatalError) Unwrap() error { return e.err } |
| 391 | |
| 392 | func (s *server) handleInitialize(ctx context.Context, raw json.RawMessage) (any, error) { |
| 393 | var p InitializeParams |
| 394 | if err := strictDecode(raw, &p); err != nil { |
| 395 | return nil, MustProtocolError(ErrInvalidParams) |
| 396 | } |
| 397 | if err := compareProtocolVersion(p.ProtocolID, p.ProtocolVersion); err != nil { |
| 398 | return nil, &fatalError{err: err} |
| 399 | } |
| 400 | result, err := s.handler.Initialize(ctx, p) |
| 401 | if err != nil { |
| 402 | s.log.Printf("extension: initialize handler failed: %v", err) |
| 403 | return nil, &fatalError{err: err} |
| 404 | } |
| 405 | if result == nil { |
| 406 | return nil, &fatalError{err: errors.New("extension: Initialize returned a nil result")} |
| 407 | } |
| 408 | result.ProtocolVersion = ProtocolVersion |
| 409 | if result.Name == "" { |
| 410 | result.Name = s.opts.Name |
| 411 | } |
| 412 | if result.Version == "" { |
| 413 | result.Version = s.opts.Version |
| 414 | } |
| 415 | if strings.TrimSpace(result.Name) == "" || strings.TrimSpace(result.Version) == "" { |
| 416 | return nil, &fatalError{err: errors.New("extension: initialize result requires a name and version")} |
| 417 | } |
| 418 | if result.StateSchemaVersion < 0 { |
| 419 | return nil, &fatalError{err: errors.New("extension: stateSchemaVersion must be non-negative")} |
| 420 | } |
| 421 | return result, nil |
| 422 | } |
| 423 | |
| 424 | // compareProtocolVersion mirrors the host's handshake identity check. |
| 425 | func compareProtocolVersion(peerID, peerVersion string) error { |
| 426 | if peerID != ProtocolID { |
| 427 | return MustProtocolError(ErrUnsupportedVersion) |
| 428 | } |
| 429 | major, err := strconv.Atoi(peerVersion) |
| 430 | if err != nil { |
| 431 | return MustProtocolError(ErrProtocolError) |
| 432 | } |
| 433 | if major != ProtocolMajor { |
| 434 | return MustProtocolError(ErrUnsupportedVersion) |
| 435 | } |
| 436 | return nil |
| 437 | } |
| 438 | |
| 439 | func (s *server) handleInitialized(context.Context, json.RawMessage) { |
| 440 | // The barrier itself opened in gateNotification, synchronously on the |
| 441 | // read loop, so no later frame can overtake it. |
| 442 | } |
| 443 | |
| 444 | func (s *server) handleShutdown(ctx context.Context, raw json.RawMessage) (any, error) { |
| 445 | var p ShutdownParams |
| 446 | if err := strictDecode(raw, &p); err != nil || p.TimeoutMillis < 0 { |
| 447 | return nil, MustProtocolError(ErrInvalidParams) |
| 448 | } |
| 449 | s.shutdownOnce.Do(func() { |
| 450 | s.mu.Lock() |
| 451 | s.state = stateShutdown |
| 452 | s.mu.Unlock() |
| 453 | if s.opts.Shutdown != nil { |
| 454 | fnCtx := ctx |
| 455 | cancel := func() {} |
| 456 | if p.TimeoutMillis > 0 { |
| 457 | fnCtx, cancel = context.WithTimeout(ctx, time.Duration(p.TimeoutMillis)*time.Millisecond) |
| 458 | } |
| 459 | defer cancel() |
| 460 | done := make(chan struct{}) |
| 461 | go func() { |
| 462 | s.opts.Shutdown(fnCtx) |
| 463 | close(done) |
| 464 | }() |
| 465 | select { |
| 466 | case <-done: |
| 467 | case <-fnCtx.Done(): |
| 468 | s.log.Printf("extension: shutdown function did not return within %dms", p.TimeoutMillis) |
| 469 | } |
| 470 | } |
| 471 | }) |
| 472 | return deferredResult{ |
| 473 | result: ShutdownResult{Accepted: true}, |
| 474 | after: func() { |
| 475 | // Orderly close: end in-flight calls, then close the read side so |
| 476 | // the read loop exits and the host sees EOF when the process |
| 477 | // exits. Serve returns nil. |
| 478 | s.conn.shutdown(nil) |
| 479 | if closer, ok := s.conn.r.(io.Closer); ok { |
| 480 | _ = closer.Close() |
| 481 | } |
| 482 | }, |
| 483 | }, nil |
| 484 | } |
| 485 | |
| 486 | // Intercept and observation |
| 487 | |
| 488 | func (s *server) handleIntercept(ctx context.Context, raw json.RawMessage) (any, error) { |
| 489 | var p InterceptParams |
| 490 | if err := strictDecode(raw, &p); err != nil { |
| 491 | return nil, MustProtocolError(ErrInvalidParams) |
| 492 | } |
| 493 | if !validInterceptEvent(p.Event) || p.Seq < 1 || p.TimeoutMillis < 0 || !jsonKeyPresent(raw, "payload") { |
| 494 | return nil, MustProtocolError(ErrInvalidParams) |
| 495 | } |
| 496 | payload, err := s.rehydrate(ctx, p.Payload, p.Externalized, "/payload") |
| 497 | if err != nil { |
| 498 | return nil, err |
| 499 | } |
| 500 | fn := s.opts.Interceptors[string(p.Event)] |
| 501 | if fn == nil { |
| 502 | fn = s.opts.Interceptors["*"] |
| 503 | } |
| 504 | if fn == nil { |
| 505 | return Continue(), nil |
| 506 | } |
| 507 | if p.TimeoutMillis > 0 { |
| 508 | var cancel context.CancelFunc |
| 509 | ctx, cancel = context.WithTimeout(ctx, time.Duration(p.TimeoutMillis)*time.Millisecond) |
| 510 | defer cancel() |
| 511 | } |
| 512 | result, err := fn(ctx, string(p.Event), payload) |
| 513 | if err != nil { |
| 514 | // The callback's advertised intercept budget expired. Return the |
| 515 | // frozen timeout reason rather than racing the host's identical timer |
| 516 | // with a generic internal error response. |
| 517 | if errors.Is(err, context.DeadlineExceeded) && errors.Is(ctx.Err(), context.DeadlineExceeded) { |
| 518 | return nil, MustProtocolError(ErrInterceptTimeout) |
| 519 | } |
| 520 | return nil, err |
| 521 | } |
| 522 | if result == nil { |
| 523 | return Continue(), nil |
| 524 | } |
| 525 | if !validInterceptDecision(result.Decision) { |
| 526 | return nil, fmt.Errorf("extension: interceptor for %q returned invalid decision %q", p.Event, result.Decision) |
| 527 | } |
| 528 | return result, nil |
| 529 | } |
| 530 | |
| 531 | func (s *server) handleEvent(ctx context.Context, raw json.RawMessage) { |
| 532 | var p EventParams |
| 533 | if err := strictDecode(raw, &p); err != nil || !validInterceptEvent(p.Event) || !jsonKeyPresent(raw, "payload") { |
| 534 | s.log.Printf("extension: dropping malformed event notification") |
| 535 | return |
| 536 | } |
| 537 | payload, err := s.rehydrate(ctx, p.Payload, p.Externalized, "/payload") |
| 538 | if err != nil { |
| 539 | s.log.Printf("extension: dropping event %q: %v", p.Event, err) |
| 540 | return |
| 541 | } |
| 542 | if s.opts.Observer != nil { |
| 543 | s.opts.Observer(ctx, string(p.Event), payload) |
| 544 | } |
| 545 | } |
| 546 | |
| 547 | func (s *server) handleResourcesChanged(ctx context.Context, raw json.RawMessage) { |
| 548 | var p ResourcesChangedParams |
| 549 | if err := strictDecode(raw, &p); err != nil || p.Paths == nil { |
| 550 | s.log.Printf("extension: dropping malformed resources/changed notification") |
| 551 | return |
| 552 | } |
| 553 | if s.opts.ResourcesChanged != nil { |
| 554 | s.opts.ResourcesChanged(ctx, p.Paths) |
| 555 | } |
| 556 | } |
| 557 | |
| 558 | // Provider broker |
| 559 | |
| 560 | func (s *server) handleProviderCatalog(ctx context.Context, raw json.RawMessage) (any, error) { |
| 561 | if s.opts.Provider == nil { |
| 562 | return nil, MustProtocolError(ErrUnknownMethod) |
| 563 | } |
| 564 | if err := strictDecode(raw, &ProviderCatalogParams{}); err != nil { |
| 565 | return nil, MustProtocolError(ErrInvalidParams) |
| 566 | } |
| 567 | providers, err := s.opts.Provider.Catalog(ctx) |
| 568 | if err != nil { |
| 569 | return nil, err |
| 570 | } |
| 571 | if providers == nil { |
| 572 | // The wire form requires an array; null fails the host's decoder. |
| 573 | providers = []ProviderDescriptor{} |
| 574 | } |
| 575 | return ProviderCatalogResult{Providers: providers}, nil |
| 576 | } |
| 577 | |
| 578 | func (s *server) handleStreamOpen(ctx context.Context, raw json.RawMessage) (any, error) { |
| 579 | if s.opts.Provider == nil { |
| 580 | return nil, MustProtocolError(ErrUnknownMethod) |
| 581 | } |
| 582 | var p StreamOpenParams |
| 583 | if err := strictDecode(raw, &p); err != nil { |
| 584 | return nil, MustProtocolError(ErrInvalidParams) |
| 585 | } |
| 586 | if p.SeqBase < 0 { |
| 587 | return nil, MustProtocolError(ErrInvalidParams) |
| 588 | } |
| 589 | if err := p.Validate(); err != nil { |
| 590 | return nil, MustProtocolError(ErrInvalidParams) |
| 591 | } |
| 592 | streamCtx, cancel := context.WithCancel(ctx) |
| 593 | chunks, err := s.opts.Provider.Stream(streamCtx, StreamRequest{ |
| 594 | StreamID: p.StreamID, |
| 595 | ProviderRef: p.ProviderRef, |
| 596 | Model: p.Model, |
| 597 | Effort: p.Effort, |
| 598 | Request: p.Request, |
| 599 | }) |
| 600 | if err != nil { |
| 601 | cancel() |
| 602 | s.log.Printf("extension: provider stream %q failed to open: %v", p.StreamID, err) |
| 603 | return nil, MustProtocolError(ErrProviderFailed) |
| 604 | } |
| 605 | if chunks == nil { |
| 606 | cancel() |
| 607 | return nil, errors.New("extension: provider returned a nil chunk channel") |
| 608 | } |
| 609 | handle := &streamHandle{cancel: cancel, done: make(chan struct{})} |
| 610 | s.streamsMu.Lock() |
| 611 | if _, exists := s.streams[p.StreamID]; exists { |
| 612 | s.streamsMu.Unlock() |
| 613 | cancel() |
| 614 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "duplicate stream id " + p.StreamID} |
| 615 | } |
| 616 | s.streams[p.StreamID] = handle |
| 617 | s.streamsMu.Unlock() |
| 618 | return deferredResult{ |
| 619 | result: StreamOpenResult{Accepted: true}, |
| 620 | after: func() { go s.pumpStream(streamCtx, p.StreamID, p.SeqBase, chunks, handle) }, |
| 621 | }, nil |
| 622 | } |
| 623 | |
| 624 | func (s *server) handleStreamCancel(_ context.Context, raw json.RawMessage) (any, error) { |
| 625 | var p StreamCancelParams |
| 626 | if err := strictDecode(raw, &p); err != nil || strings.TrimSpace(p.StreamID) == "" { |
| 627 | return nil, MustProtocolError(ErrInvalidParams) |
| 628 | } |
| 629 | s.streamsMu.Lock() |
| 630 | handle := s.streams[p.StreamID] |
| 631 | s.streamsMu.Unlock() |
| 632 | if handle == nil { |
| 633 | return StreamCancelResult{Cancelled: false}, nil |
| 634 | } |
| 635 | handle.cancel() |
| 636 | return StreamCancelResult{Cancelled: true}, nil |
| 637 | } |
| 638 | |
| 639 | // pumpStream forwards one provider channel onto the wire: chunks become |
| 640 | // stream/chunk notifications with contiguous 1-based seqs (from SeqBase), |
| 641 | // and exactly one stream/end closes the stream — clean on channel close, |
| 642 | // with error on an error chunk, interrupted on cancel. A cancel processed by |
| 643 | // the SDK is never trailed by another chunk. |
| 644 | func (s *server) pumpStream(ctx context.Context, streamID string, seqBase int, chunks <-chan StreamChunk, handle *streamHandle) { |
| 645 | defer close(handle.done) |
| 646 | defer func() { |
| 647 | s.streamsMu.Lock() |
| 648 | delete(s.streams, streamID) |
| 649 | s.streamsMu.Unlock() |
| 650 | }() |
| 651 | seq := int64(seqBase) |
| 652 | if seq < 1 { |
| 653 | seq = 1 |
| 654 | } |
| 655 | var lastSeq int64 |
| 656 | end := StreamEndParams{StreamID: streamID} |
| 657 | for { |
| 658 | // A cancel must never be trailed by one more chunk, so check before |
| 659 | // every receive and again before every send. |
| 660 | select { |
| 661 | case <-ctx.Done(): |
| 662 | end.LastSeq, end.Interrupted = lastSeq, true |
| 663 | s.sendStreamEnd(&end) |
| 664 | return |
| 665 | default: |
| 666 | } |
| 667 | select { |
| 668 | case <-ctx.Done(): |
| 669 | end.LastSeq, end.Interrupted = lastSeq, true |
| 670 | s.sendStreamEnd(&end) |
| 671 | return |
| 672 | case chunk, ok := <-chunks: |
| 673 | if !ok { |
| 674 | end.LastSeq = lastSeq |
| 675 | s.sendStreamEnd(&end) |
| 676 | return |
| 677 | } |
| 678 | if chunk.Type == ChunkError { |
| 679 | end.LastSeq = lastSeq |
| 680 | end.Error = frozenErrorSpecs[ErrProviderFailed].Message |
| 681 | if chunk.Error != nil && strings.TrimSpace(chunk.Error.Message) != "" { |
| 682 | end.Error = chunk.Error.Message |
| 683 | } |
| 684 | s.sendStreamEnd(&end) |
| 685 | return |
| 686 | } |
| 687 | if err := chunk.Validate(); err != nil { |
| 688 | s.log.Printf("extension: provider stream %q produced an invalid chunk: %v", streamID, err) |
| 689 | end.LastSeq = lastSeq |
| 690 | end.Error = "the extension provider produced an invalid chunk" |
| 691 | s.sendStreamEnd(&end) |
| 692 | return |
| 693 | } |
| 694 | if err := s.conn.notify(MethodExtensionProviderStreamChunk, StreamChunkParams{ |
| 695 | StreamID: streamID, Seq: seq, Chunk: chunk, |
| 696 | }); err != nil { |
| 697 | s.log.Printf("extension: provider stream %q could not deliver chunk %d: %v", streamID, seq, err) |
| 698 | return |
| 699 | } |
| 700 | lastSeq = seq |
| 701 | seq++ |
| 702 | } |
| 703 | } |
| 704 | } |
| 705 | |
| 706 | func (s *server) sendStreamEnd(end *StreamEndParams) { |
| 707 | if err := s.conn.notify(MethodExtensionProviderStreamEnd, *end); err != nil { |
| 708 | s.log.Printf("extension: provider stream %q could not deliver stream end: %v", end.StreamID, err) |
| 709 | } |
| 710 | } |
| 711 | |
| 712 | // UI handlers (Host → Extension) |
| 713 | |
| 714 | func (s *server) handleUIAction(ctx context.Context, raw json.RawMessage) (any, error) { |
| 715 | if s.opts.UI.Action == nil { |
| 716 | return nil, MustProtocolError(ErrUnknownMethod) |
| 717 | } |
| 718 | var p UIActionParams |
| 719 | if err := strictDecode(raw, &p); err != nil || strings.TrimSpace(p.ActionID) == "" || strings.TrimSpace(p.SessionID) == "" { |
| 720 | return nil, MustProtocolError(ErrInvalidParams) |
| 721 | } |
| 722 | if err := s.opts.UI.Action(ctx, p.ActionID, p.Args); err != nil { |
| 723 | return UIActionResult{Accepted: false, Message: err.Error()}, nil |
| 724 | } |
| 725 | return UIActionResult{Accepted: true}, nil |
| 726 | } |
| 727 | |
| 728 | func (s *server) handleUISubmit(ctx context.Context, raw json.RawMessage) (any, error) { |
| 729 | if s.opts.UI.Submit == nil { |
| 730 | return nil, MustProtocolError(ErrUnknownMethod) |
| 731 | } |
| 732 | var p UISubmitParams |
| 733 | if err := strictDecode(raw, &p); err != nil || strings.TrimSpace(p.SurfaceID) == "" || |
| 734 | strings.TrimSpace(p.SessionID) == "" || p.Values == nil { |
| 735 | return nil, MustProtocolError(ErrInvalidParams) |
| 736 | } |
| 737 | if err := s.opts.UI.Submit(ctx, p.SurfaceID, p.Values); err != nil { |
| 738 | s.log.Printf("extension: UI submit for surface %q failed: %v", p.SurfaceID, err) |
| 739 | return UISubmitResult{Accepted: false}, nil |
| 740 | } |
| 741 | return UISubmitResult{Accepted: true}, nil |
| 742 | } |
| 743 | |
| 744 | // HostUI: Extension → Host UI client |
| 745 | |
| 746 | // HostUI is the sidecar's client for the host's structured UI surfaces. The |
| 747 | // zero value is ready to use; every method takes the context of an SDK |
| 748 | // callback (interceptor, observer, provider, UI, or shutdown) and fails with |
| 749 | // ErrNoConnection otherwise, and with ErrNotReady before the handshake |
| 750 | // barrier opens. Surfaces are structured-only by design: there is no way to |
| 751 | // send HTML, CSS, JavaScript, or URLs. |
| 752 | type HostUI struct{} |
| 753 | |
| 754 | // uiAnswerKey is the field key the host uses for single-field prompts. |
| 755 | const uiAnswerKey = "value" |
| 756 | |
| 757 | // PublishStatus publishes or replaces a one-line status surface. |
| 758 | func (HostUI) PublishStatus(ctx context.Context, sessionID string, generation uint64, surfaceID string, p UIStatusPayload) error { |
| 759 | if strings.TrimSpace(p.Label) == "" { |
| 760 | return errors.New("extension: status payload requires a label") |
| 761 | } |
| 762 | if !validUISeverity(p.Severity) { |
| 763 | return fmt.Errorf("extension: invalid severity %q", p.Severity) |
| 764 | } |
| 765 | return publishSurface(ctx, sessionID, generation, surfaceID, UISurfaceStatus, p) |
| 766 | } |
| 767 | |
| 768 | // PublishCard publishes or replaces a rich read-only card surface. |
| 769 | func (HostUI) PublishCard(ctx context.Context, sessionID string, generation uint64, surfaceID string, p UICardPayload) error { |
| 770 | for i, field := range p.Fields { |
| 771 | if strings.TrimSpace(field.Key) == "" { |
| 772 | return fmt.Errorf("extension: card field %d requires a key", i) |
| 773 | } |
| 774 | } |
| 775 | for i, action := range p.Actions { |
| 776 | if strings.TrimSpace(action.ActionID) == "" || strings.TrimSpace(action.Label) == "" { |
| 777 | return fmt.Errorf("extension: card action %d requires an actionId and label", i) |
| 778 | } |
| 779 | } |
| 780 | return publishSurface(ctx, sessionID, generation, surfaceID, UISurfaceCard, p) |
| 781 | } |
| 782 | |
| 783 | // PublishForm publishes or replaces an editable form surface; submissions |
| 784 | // return through the Options.UI.Submit callback. |
| 785 | func (HostUI) PublishForm(ctx context.Context, sessionID string, generation uint64, surfaceID string, p UIFormPayload) error { |
| 786 | if err := validateFormPayload(p); err != nil { |
| 787 | return err |
| 788 | } |
| 789 | return publishSurface(ctx, sessionID, generation, surfaceID, UISurfaceForm, p) |
| 790 | } |
| 791 | |
| 792 | // PublishNotification publishes a transient toast-style message. |
| 793 | func (HostUI) PublishNotification(ctx context.Context, sessionID string, generation uint64, surfaceID string, p UINotificationPayload) error { |
| 794 | if strings.TrimSpace(p.Title) == "" { |
| 795 | return errors.New("extension: notification payload requires a title") |
| 796 | } |
| 797 | if !validUISeverity(p.Severity) { |
| 798 | return fmt.Errorf("extension: invalid severity %q", p.Severity) |
| 799 | } |
| 800 | return publishSurface(ctx, sessionID, generation, surfaceID, UISurfaceNotification, p) |
| 801 | } |
| 802 | |
| 803 | func publishSurface(ctx context.Context, sessionID string, generation uint64, surfaceID string, kind UISurfaceKind, payload any) error { |
| 804 | s := serverFrom(ctx) |
| 805 | if s == nil { |
| 806 | return ErrNoConnection |
| 807 | } |
| 808 | if strings.TrimSpace(surfaceID) == "" || strings.TrimSpace(sessionID) == "" { |
| 809 | return errors.New("extension: surfaceId and sessionId are required") |
| 810 | } |
| 811 | raw, err := json.Marshal(payload) |
| 812 | if err != nil { |
| 813 | return fmt.Errorf("extension: marshal %s payload: %w", kind, err) |
| 814 | } |
| 815 | resultRaw, err := s.callHost(ctx, MethodHostUIPublish, UIPublishParams{ |
| 816 | SurfaceID: surfaceID, SessionID: sessionID, Generation: generation, Kind: kind, Payload: raw, |
| 817 | }) |
| 818 | if err != nil { |
| 819 | return err |
| 820 | } |
| 821 | var result UIPublishResult |
| 822 | if err := strictDecode(resultRaw, &result); err != nil { |
| 823 | return &ProtocolError{Reason: ErrProtocolError, Message: "invalid host/ui/publish result"} |
| 824 | } |
| 825 | if !result.Accepted { |
| 826 | return fmt.Errorf("extension: host rejected the %s surface %q", kind, surfaceID) |
| 827 | } |
| 828 | return nil |
| 829 | } |
| 830 | |
| 831 | // InputPrompt configures RequestInput. |
| 832 | type InputPrompt struct { |
| 833 | Title string |
| 834 | Message string |
| 835 | Label string |
| 836 | Default string |
| 837 | Required bool |
| 838 | } |
| 839 | |
| 840 | // SelectPrompt configures RequestSelect. |
| 841 | type SelectPrompt struct { |
| 842 | Title string |
| 843 | Message string |
| 844 | Label string |
| 845 | Options []string |
| 846 | Default string |
| 847 | Required bool |
| 848 | } |
| 849 | |
| 850 | // MultiSelectPrompt configures RequestMultiSelect. |
| 851 | type MultiSelectPrompt struct { |
| 852 | Title string |
| 853 | Message string |
| 854 | Label string |
| 855 | Options []string |
| 856 | Required bool |
| 857 | } |
| 858 | |
| 859 | // RequestConfirm blocks on a yes/no prompt; the bool is the user's answer. |
| 860 | // A dismissed prompt returns ErrUICancelled. |
| 861 | func (h HostUI) RequestConfirm(ctx context.Context, sessionID string, generation uint64, surfaceID, message string) (bool, error) { |
| 862 | form := UIFormPayload{ |
| 863 | Message: message, |
| 864 | Fields: []UIFormField{{Key: uiAnswerKey, Label: message, Kind: UIFieldConfirm}}, |
| 865 | } |
| 866 | values, err := h.requestPrompt(ctx, sessionID, generation, surfaceID, UIRequestConfirm, form) |
| 867 | if err != nil { |
| 868 | return false, err |
| 869 | } |
| 870 | answer, _ := values[uiAnswerKey].(bool) |
| 871 | return answer, nil |
| 872 | } |
| 873 | |
| 874 | // RequestInput blocks on a free-text prompt and returns the entered text. |
| 875 | func (h HostUI) RequestInput(ctx context.Context, sessionID string, generation uint64, surfaceID string, p InputPrompt) (string, error) { |
| 876 | field := UIFormField{Key: uiAnswerKey, Label: p.Label, Kind: UIFieldInput, Required: p.Required} |
| 877 | if p.Default != "" { |
| 878 | field.Default = p.Default |
| 879 | } |
| 880 | values, err := h.requestPrompt(ctx, sessionID, generation, surfaceID, UIRequestInput, UIFormPayload{ |
| 881 | Title: p.Title, Message: p.Message, Fields: []UIFormField{field}, |
| 882 | }) |
| 883 | if err != nil { |
| 884 | return "", err |
| 885 | } |
| 886 | answer, _ := values[uiAnswerKey].(string) |
| 887 | return answer, nil |
| 888 | } |
| 889 | |
| 890 | // RequestSelect blocks on a single-choice prompt and returns the picked |
| 891 | // option. |
| 892 | func (h HostUI) RequestSelect(ctx context.Context, sessionID string, generation uint64, surfaceID string, p SelectPrompt) (string, error) { |
| 893 | if len(p.Options) == 0 { |
| 894 | return "", errors.New("extension: select prompt requires options") |
| 895 | } |
| 896 | field := UIFormField{Key: uiAnswerKey, Label: p.Label, Kind: UIFieldSelect, Options: p.Options, Required: p.Required} |
| 897 | if p.Default != "" { |
| 898 | field.Default = p.Default |
| 899 | } |
| 900 | values, err := h.requestPrompt(ctx, sessionID, generation, surfaceID, UIRequestSelect, UIFormPayload{ |
| 901 | Title: p.Title, Message: p.Message, Fields: []UIFormField{field}, |
| 902 | }) |
| 903 | if err != nil { |
| 904 | return "", err |
| 905 | } |
| 906 | answer, _ := values[uiAnswerKey].(string) |
| 907 | return answer, nil |
| 908 | } |
| 909 | |
| 910 | // RequestMultiSelect blocks on a multi-choice prompt and returns the picked |
| 911 | // options. |
| 912 | func (h HostUI) RequestMultiSelect(ctx context.Context, sessionID string, generation uint64, surfaceID string, p MultiSelectPrompt) ([]string, error) { |
| 913 | if len(p.Options) == 0 { |
| 914 | return nil, errors.New("extension: multiselect prompt requires options") |
| 915 | } |
| 916 | field := UIFormField{Key: uiAnswerKey, Label: p.Label, Kind: UIFieldMultiselect, Options: p.Options, Required: p.Required} |
| 917 | values, err := h.requestPrompt(ctx, sessionID, generation, surfaceID, UIRequestMultiselect, UIFormPayload{ |
| 918 | Title: p.Title, Message: p.Message, Fields: []UIFormField{field}, |
| 919 | }) |
| 920 | if err != nil { |
| 921 | return nil, err |
| 922 | } |
| 923 | switch answer := values[uiAnswerKey].(type) { |
| 924 | case []string: |
| 925 | return answer, nil |
| 926 | case []any: |
| 927 | out := make([]string, 0, len(answer)) |
| 928 | for _, item := range answer { |
| 929 | text, ok := item.(string) |
| 930 | if !ok { |
| 931 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/ui/request multiselect answer is not a string list"} |
| 932 | } |
| 933 | out = append(out, text) |
| 934 | } |
| 935 | return out, nil |
| 936 | case nil: |
| 937 | return []string{}, nil |
| 938 | default: |
| 939 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/ui/request multiselect answer is not a string list"} |
| 940 | } |
| 941 | } |
| 942 | |
| 943 | // RequestForm blocks on a fully custom form prompt and returns all values |
| 944 | // keyed by field key. It is the structured escape hatch behind the typed |
| 945 | // prompt helpers. |
| 946 | func (h HostUI) RequestForm(ctx context.Context, sessionID string, generation uint64, surfaceID string, form UIFormPayload) (map[string]any, error) { |
| 947 | if err := validateFormPayload(form); err != nil { |
| 948 | return nil, err |
| 949 | } |
| 950 | return h.requestPrompt(ctx, sessionID, generation, surfaceID, UIRequestInput, form) |
| 951 | } |
| 952 | |
| 953 | func (h HostUI) requestPrompt(ctx context.Context, sessionID string, generation uint64, surfaceID string, kind UIRequestKind, form UIFormPayload) (map[string]any, error) { |
| 954 | s := serverFrom(ctx) |
| 955 | if s == nil { |
| 956 | return nil, ErrNoConnection |
| 957 | } |
| 958 | if strings.TrimSpace(surfaceID) == "" || strings.TrimSpace(sessionID) == "" { |
| 959 | return nil, errors.New("extension: surfaceId and sessionId are required") |
| 960 | } |
| 961 | raw, err := json.Marshal(form) |
| 962 | if err != nil { |
| 963 | return nil, fmt.Errorf("extension: marshal %s payload: %w", kind, err) |
| 964 | } |
| 965 | resultRaw, err := s.callHost(ctx, MethodHostUIRequest, UIRequestParams{ |
| 966 | SurfaceID: surfaceID, SessionID: sessionID, Generation: generation, Kind: kind, Payload: raw, |
| 967 | }) |
| 968 | if err != nil { |
| 969 | return nil, err |
| 970 | } |
| 971 | var result UIRequestResult |
| 972 | if err := strictDecode(resultRaw, &result); err != nil { |
| 973 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "invalid host/ui/request result"} |
| 974 | } |
| 975 | if result.Cancelled { |
| 976 | return nil, ErrUICancelled |
| 977 | } |
| 978 | return result.Values, nil |
| 979 | } |
| 980 | |
| 981 | func validateFormPayload(p UIFormPayload) error { |
| 982 | if p.Fields == nil { |
| 983 | return errors.New("extension: form payload requires a fields array (possibly empty)") |
| 984 | } |
| 985 | for i, field := range p.Fields { |
| 986 | if strings.TrimSpace(field.Key) == "" { |
| 987 | return fmt.Errorf("extension: form field %d requires a key", i) |
| 988 | } |
| 989 | if !validUIFieldKind(field.Kind) { |
| 990 | return fmt.Errorf("extension: form field %q has invalid kind %q", field.Key, field.Kind) |
| 991 | } |
| 992 | } |
| 993 | return nil |
| 994 | } |
| 995 | |
| 996 | // Content refs (Extension → Host) |
| 997 | |
| 998 | // ReadContentRef pages one whole content ref back from the host in |
| 999 | // ContentRefChunkBytes chunks, verifies the reassembled byte count and |
| 1000 | // SHA-256 against the host's own report, and fails on any inconsistency. An |
| 1001 | // expired or unknown ref returns a *ProtocolError with Reason |
| 1002 | // ErrContentRefExpired. |
| 1003 | func ReadContentRef(ctx context.Context, ref string) ([]byte, error) { |
| 1004 | s := serverFrom(ctx) |
| 1005 | if s == nil { |
| 1006 | return nil, ErrNoConnection |
| 1007 | } |
| 1008 | if strings.TrimSpace(ref) == "" { |
| 1009 | return nil, errors.New("extension: content ref is required") |
| 1010 | } |
| 1011 | var out []byte |
| 1012 | var offset int64 |
| 1013 | for { |
| 1014 | raw, err := s.callHost(ctx, MethodHostContentRead, ContentReadParams{ContentRef: ref, Offset: offset}) |
| 1015 | if err != nil { |
| 1016 | return nil, err |
| 1017 | } |
| 1018 | var result ContentReadResult |
| 1019 | if err := strictDecode(raw, &result); err != nil { |
| 1020 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "invalid host/content/read result"} |
| 1021 | } |
| 1022 | if result.ContentRef != ref || result.Offset != offset { |
| 1023 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/content/read answered a different ref or offset"} |
| 1024 | } |
| 1025 | if result.Encoding != ContentUTF8 { |
| 1026 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/content/read answered with an unknown encoding"} |
| 1027 | } |
| 1028 | if result.TotalBytes > ContentRefObjectBytes { |
| 1029 | return nil, &ProtocolError{Reason: ErrFrameTooLarge, Message: fmt.Sprintf( |
| 1030 | "content ref is %d bytes, above the %d byte object cap", result.TotalBytes, ContentRefObjectBytes)} |
| 1031 | } |
| 1032 | chunk, err := base64.StdEncoding.DecodeString(result.DataBase64) |
| 1033 | if err != nil { |
| 1034 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/content/read returned invalid base64"} |
| 1035 | } |
| 1036 | if len(chunk) > ContentRefChunkBytes { |
| 1037 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/content/read returned an oversized chunk"} |
| 1038 | } |
| 1039 | out = append(out, chunk...) |
| 1040 | if result.NextOffset == nil { |
| 1041 | if int64(len(out)) != result.TotalBytes { |
| 1042 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: fmt.Sprintf( |
| 1043 | "content ref reassembled to %d bytes, host reported %d", len(out), result.TotalBytes)} |
| 1044 | } |
| 1045 | sum := sha256.Sum256(out) |
| 1046 | if !strings.EqualFold(hex.EncodeToString(sum[:]), result.SHA256) { |
| 1047 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "content ref SHA-256 mismatch"} |
| 1048 | } |
| 1049 | return out, nil |
| 1050 | } |
| 1051 | if *result.NextOffset <= offset { |
| 1052 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "host/content/read made no progress"} |
| 1053 | } |
| 1054 | offset = *result.NextOffset |
| 1055 | } |
| 1056 | } |
| 1057 | |
| 1058 | // ResolveExternalized rehydrates one owner document's externalizable field. |
| 1059 | // raw is the field's inline value and externalized the owner's envelope, at |
| 1060 | // the schema-registered JSON pointer ("/payload" for intercept and event |
| 1061 | // params, "/replacement" for intercept results). With an empty envelope the |
| 1062 | // inline value passes through; otherwise the envelope must hold exactly the |
| 1063 | // pointer's descriptor, and the ref is paged back and verified against the |
| 1064 | // descriptor's byte count and SHA-256 before it is returned. An inline value |
| 1065 | // alongside an envelope, a wrong pointer, or unverifiable content is a |
| 1066 | // protocol error — never decode bytes the peer did not prove. |
| 1067 | // |
| 1068 | // Intercept and event payloads are resolved automatically before the |
| 1069 | // interceptor/observer runs; this helper remains for manual use. |
| 1070 | func ResolveExternalized(ctx context.Context, raw json.RawMessage, externalized []ExternalizedField, pointer string) (json.RawMessage, error) { |
| 1071 | if serverFrom(ctx) == nil { |
| 1072 | return nil, ErrNoConnection |
| 1073 | } |
| 1074 | return resolveExternalized(ctx, raw, externalized, pointer) |
| 1075 | } |
| 1076 | |
| 1077 | func (s *server) rehydrate(ctx context.Context, raw json.RawMessage, externalized []ExternalizedField, pointer string) (json.RawMessage, error) { |
| 1078 | return resolveExternalized(ctx, raw, externalized, pointer) |
| 1079 | } |
| 1080 | |
| 1081 | func resolveExternalized(ctx context.Context, raw json.RawMessage, externalized []ExternalizedField, pointer string) (json.RawMessage, error) { |
| 1082 | if len(externalized) == 0 { |
| 1083 | return raw, nil |
| 1084 | } |
| 1085 | if inline := bytes.TrimSpace(raw); len(inline) > 0 && !bytes.Equal(inline, []byte("null")) { |
| 1086 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "document carries both an inline value and an externalized envelope"} |
| 1087 | } |
| 1088 | if len(externalized) != 1 || externalized[0].JSONPointer != pointer { |
| 1089 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: fmt.Sprintf( |
| 1090 | "externalized envelope must hold exactly the %s descriptor", pointer)} |
| 1091 | } |
| 1092 | descriptor := externalized[0] |
| 1093 | if descriptor.TotalBytes > ContentRefObjectBytes { |
| 1094 | return nil, &ProtocolError{Reason: ErrFrameTooLarge, Message: fmt.Sprintf( |
| 1095 | "externalized value is %d bytes, above the %d byte object cap", descriptor.TotalBytes, ContentRefObjectBytes)} |
| 1096 | } |
| 1097 | data, err := ReadContentRef(ctx, descriptor.ContentRef) |
| 1098 | if err != nil { |
| 1099 | return nil, err |
| 1100 | } |
| 1101 | if int64(len(data)) != descriptor.TotalBytes { |
| 1102 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: fmt.Sprintf( |
| 1103 | "externalized value reassembled to %d bytes, want %d", len(data), descriptor.TotalBytes)} |
| 1104 | } |
| 1105 | sum := sha256.Sum256(data) |
| 1106 | if !strings.EqualFold(hex.EncodeToString(sum[:]), descriptor.SHA256) { |
| 1107 | return nil, &ProtocolError{Reason: ErrProtocolError, Message: "externalized value SHA-256 mismatch"} |
| 1108 | } |
| 1109 | return data, nil |
| 1110 | } |
| 1111 | |
| 1112 | // shared helpers |
| 1113 | |
| 1114 | // callHost issues one Extension → Host request behind the handshake barrier |
| 1115 | // and maps a structured wire error back to a *ProtocolError. |
| 1116 | func (s *server) callHost(ctx context.Context, method string, params any) (json.RawMessage, error) { |
| 1117 | if err := s.checkReady(); err != nil { |
| 1118 | return nil, err |
| 1119 | } |
| 1120 | raw, err := s.conn.call(ctx, method, params) |
| 1121 | if err != nil { |
| 1122 | return nil, mapCallError(err) |
| 1123 | } |
| 1124 | return raw, nil |
| 1125 | } |
| 1126 | |
| 1127 | // mapCallError converts a peer's JSON-RPC error into a *ProtocolError when it |
| 1128 | // carries a frozen reason. |
| 1129 | func mapCallError(err error) error { |
| 1130 | var respErr *ResponseError |
| 1131 | if errors.As(err, &respErr) { |
| 1132 | var data ProtocolErrorData |
| 1133 | if len(respErr.Data) > 0 && json.Unmarshal(respErr.Data, &data) == nil && data.Validate() == nil { |
| 1134 | return &ProtocolError{Reason: data.Reason, Message: respErr.Message} |
| 1135 | } |
| 1136 | } |
| 1137 | return err |
| 1138 | } |
| 1139 | |
| 1140 | // strictDecode decodes one params/result document rejecting unknown fields |
| 1141 | // and trailing JSON, mirroring the host's strict decoder envelope rules. |
| 1142 | func strictDecode(raw json.RawMessage, v any) error { |
| 1143 | if len(bytes.TrimSpace(raw)) == 0 { |
| 1144 | raw = json.RawMessage(`{}`) |
| 1145 | } |
| 1146 | decoder := json.NewDecoder(bytes.NewReader(raw)) |
| 1147 | decoder.DisallowUnknownFields() |
| 1148 | if err := decoder.Decode(v); err != nil { |
| 1149 | return err |
| 1150 | } |
| 1151 | var extra any |
| 1152 | if err := decoder.Decode(&extra); !errors.Is(err, io.EOF) { |
| 1153 | return errors.New("trailing JSON") |
| 1154 | } |
| 1155 | return nil |
| 1156 | } |
| 1157 | |
| 1158 | // jsonKeyPresent reports whether raw is an object containing key, for |
| 1159 | // required-but-nullable fields such as the externalizable payload. |
| 1160 | func jsonKeyPresent(raw json.RawMessage, key string) bool { |
| 1161 | var object map[string]json.RawMessage |
| 1162 | if err := json.Unmarshal(raw, &object); err != nil { |
| 1163 | return false |
| 1164 | } |
| 1165 | _, ok := object[key] |
| 1166 | return ok |
| 1167 | } |
| 1168 |