| 1 | package extension |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "encoding/json" |
| 6 | "fmt" |
| 7 | "strings" |
| 8 | ) |
| 9 | |
| 10 | // This file holds the handwritten half of the SDK's type layer: behavior the |
| 11 | // generator cannot emit (validators, error constructors, enum helpers). The |
| 12 | // wire DTOs, enums, method names, frozen limits, and the frozen error table |
| 13 | // live in types_generated.go, mirrored from the host's |
| 14 | // internal/extension/protocol package by cmd/extension-protocol-gen. |
| 15 | // |
| 16 | // Stability contract (mirrored from the host): within major version 1 only |
| 17 | // optional fields, new enum values, and new methods may be added. Existing |
| 18 | // required fields, method names, directions, limits, error reasons, and |
| 19 | // semantics never change. |
| 20 | |
| 21 | // Enum helpers |
| 22 | |
| 23 | // InterceptEvents returns the 17 frozen hook point names, sorted. |
| 24 | func InterceptEvents() []string { |
| 25 | out := []string{ |
| 26 | string(EventSessionStart), string(EventSessionEnd), string(EventSessionLoad), |
| 27 | string(EventSessionSave), string(EventSessionRotate), string(EventInputReceive), |
| 28 | string(EventAgentBeforeStart), string(EventSystemPromptBuild), string(EventContextPrepare), |
| 29 | string(EventProviderRequest), string(EventProviderResponse), string(EventToolBefore), |
| 30 | string(EventToolAfter), string(EventPermissionDecision), string(EventCompactionPrepare), |
| 31 | string(EventCompactionComplete), string(EventFrontendEvent), |
| 32 | } |
| 33 | sortStrings(out) |
| 34 | return out |
| 35 | } |
| 36 | |
| 37 | func validInterceptEvent(event InterceptEvent) bool { |
| 38 | switch event { |
| 39 | case EventSessionStart, EventSessionEnd, EventSessionLoad, EventSessionSave, |
| 40 | EventSessionRotate, EventInputReceive, EventAgentBeforeStart, |
| 41 | EventSystemPromptBuild, EventContextPrepare, EventProviderRequest, |
| 42 | EventProviderResponse, EventToolBefore, EventToolAfter, |
| 43 | EventPermissionDecision, EventCompactionPrepare, EventCompactionComplete, |
| 44 | EventFrontendEvent: |
| 45 | return true |
| 46 | } |
| 47 | return false |
| 48 | } |
| 49 | |
| 50 | func validInterceptDecision(decision InterceptDecision) bool { |
| 51 | switch decision { |
| 52 | case DecisionContinue, DecisionBlock, DecisionReplace, DecisionAllow, DecisionDeny: |
| 53 | return true |
| 54 | } |
| 55 | return false |
| 56 | } |
| 57 | |
| 58 | func validUIFieldKind(kind UIFieldKind) bool { |
| 59 | switch kind { |
| 60 | case UIFieldConfirm, UIFieldInput, UIFieldSelect, UIFieldMultiselect: |
| 61 | return true |
| 62 | } |
| 63 | return false |
| 64 | } |
| 65 | |
| 66 | func validUISeverity(severity UISeverity) bool { |
| 67 | switch severity { |
| 68 | case "", UISeverityInfo, UISeverityWarn, UISeverityError: |
| 69 | return true |
| 70 | } |
| 71 | return false |
| 72 | } |
| 73 | |
| 74 | // Wire DTO validators |
| 75 | |
| 76 | // Validate enforces the deterministic wire shape. |
| 77 | func (request ProviderRequest) Validate() error { |
| 78 | if request.Messages == nil || request.Tools == nil { |
| 79 | return validationError("messages and tools must be arrays") |
| 80 | } |
| 81 | if request.MaxTokens < 0 { |
| 82 | return validationError("maxTokens must be non-negative") |
| 83 | } |
| 84 | for _, tool := range request.Tools { |
| 85 | parameters := bytes.TrimSpace(tool.Parameters) |
| 86 | if len(parameters) == 0 || parameters[0] != '{' || !json.Valid(parameters) { |
| 87 | return validationError("tool parameters must be a JSON object") |
| 88 | } |
| 89 | } |
| 90 | return nil |
| 91 | } |
| 92 | |
| 93 | // Validate enforces chunk invariants the tags cannot express. |
| 94 | func (chunk ProviderChunk) Validate() error { |
| 95 | if chunk.ArgChars < 0 { |
| 96 | return validationError("argChars must be non-negative") |
| 97 | } |
| 98 | if chunk.Type == ChunkError && chunk.Error == nil { |
| 99 | return validationError("error chunks require error") |
| 100 | } |
| 101 | if chunk.Type != ChunkError && chunk.Error != nil { |
| 102 | return validationError("non-error chunks forbid error") |
| 103 | } |
| 104 | if chunk.Type == ChunkUsage && chunk.Usage == nil { |
| 105 | return validationError("usage chunks require usage") |
| 106 | } |
| 107 | return nil |
| 108 | } |
| 109 | |
| 110 | // Validate enforces required identifiers plus the request invariants. |
| 111 | func (p StreamOpenParams) Validate() error { |
| 112 | if strings.TrimSpace(p.StreamID) == "" || strings.TrimSpace(p.ProviderRef) == "" { |
| 113 | return validationError("streamId and providerRef are required") |
| 114 | } |
| 115 | return p.Request.Validate() |
| 116 | } |
| 117 | |
| 118 | // Validate enforces stream ordering preconditions and chunk invariants. |
| 119 | func (p StreamChunkParams) Validate() error { |
| 120 | if strings.TrimSpace(p.StreamID) == "" { |
| 121 | return validationError("streamId is required") |
| 122 | } |
| 123 | if p.Seq < 1 { |
| 124 | return validationError("seq must be >= 1") |
| 125 | } |
| 126 | return p.Chunk.Validate() |
| 127 | } |
| 128 | |
| 129 | // Validate checks the data against the frozen error table. |
| 130 | func (d ProtocolErrorData) Validate() error { |
| 131 | spec, ok := frozenErrorSpecs[d.Reason] |
| 132 | if !ok { |
| 133 | return fmt.Errorf("unknown extension error reason %q", d.Reason) |
| 134 | } |
| 135 | if d.Retryable != spec.Retryable { |
| 136 | return fmt.Errorf("retryable must match the frozen error table for %q", d.Reason) |
| 137 | } |
| 138 | return nil |
| 139 | } |
| 140 | |
| 141 | // ProtocolError |
| 142 | |
| 143 | // ProtocolError is the extension protocol's structured error. Handlers may |
| 144 | // return one to choose the wire reason; the SDK answers with the frozen |
| 145 | // JSON-RPC code and structured data. Message should stay generic: it crosses |
| 146 | // the wire verbatim. |
| 147 | type ProtocolError struct { |
| 148 | Reason ErrorReason |
| 149 | Message string |
| 150 | } |
| 151 | |
| 152 | func (e *ProtocolError) Error() string { |
| 153 | if e == nil { |
| 154 | return "" |
| 155 | } |
| 156 | return e.Message |
| 157 | } |
| 158 | |
| 159 | // NewProtocolError builds the frozen error for a reason. |
| 160 | func NewProtocolError(reason ErrorReason) (*ProtocolError, error) { |
| 161 | spec, ok := frozenErrorSpecs[reason] |
| 162 | if !ok { |
| 163 | return nil, fmt.Errorf("extension: unknown error reason %q", reason) |
| 164 | } |
| 165 | return &ProtocolError{Reason: reason, Message: spec.Message}, nil |
| 166 | } |
| 167 | |
| 168 | // MustProtocolError is NewProtocolError for reasons known to be frozen. |
| 169 | func MustProtocolError(reason ErrorReason) *ProtocolError { |
| 170 | errValue, err := NewProtocolError(reason) |
| 171 | if err != nil { |
| 172 | panic(err) |
| 173 | } |
| 174 | return errValue |
| 175 | } |
| 176 | |
| 177 | // internal helpers shared with the validator |
| 178 | |
| 179 | type validationFailure struct{ message string } |
| 180 | |
| 181 | func (e *validationFailure) Error() string { return e.message } |
| 182 | |
| 183 | func validationError(message string) error { return &validationFailure{message: message} } |
| 184 | |
| 185 | func sortStrings(values []string) { |
| 186 | for i := 1; i < len(values); i++ { |
| 187 | for j := i; j > 0 && values[j] < values[j-1]; j-- { |
| 188 | values[j], values[j-1] = values[j-1], values[j] |
| 189 | } |
| 190 | } |
| 191 | } |
| 192 |