RpcError

type: module path: "@root/src/PuduLangMcp/Errors/RpcError.pudu" fidelity: Active grammar: "[[grammar/pudu]]" depth_score: 0.45 depth_status: MODERATE coupling: 2 interface_stability: 0.9 tags: [module] aliases: [Protocol Error]

Purpose

Every way a request is refused at the protocol level, and its JSON-RPC wire form (code, message, optional data).

Interface

Signatures

export type ProtocolError
  = ParseError(Str)                 // the line is not JSON
  | InvalidRequest(Str)             // JSON, but not a single JSON-RPC request or notification
  | MethodNotFound(Str)             // method name
  | InvalidParams(Str)              // what is wrong with the parameters
  | ResourceNotFound(Str)           // uri
  | UnsupportedVersion(Str)         // requested version
  | Internal(Str)

export fn code(problem: &ProtocolError) -> Int
export fn message(problem: &ProtocolError) -> Str
export fn data(problem: &ProtocolError) -> Option[Json.Json]

Governance

• UnsupportedVersion data is { supported: [...], requested }, supported modern first.
• ResourceNotFound is -32602 with data.uri.

Linkage

• Requires: [[src/PuduLangMcp/Constants/Protocol]], Std.Json.
• Consumed by: [[src/PuduLangMcp/Domain/Rpc/Reply]], [[src/PuduLangMcp/Domain/Protocol/Negotiation]], App/*.

Algorithm

code maps each case to its constant; message gives the case's fixed prefix plus its detail; data answers only for the two cases that carry structured data.

Negative Logic (Prohibited Paths)

• No error echoes a whole request back; details are bounded by the caller.

Edge Cases

• MethodNotFound("") still names the problem ("Method not found: ").

Depth

DEPTH 0.45. Small surface; hides the code table and data shapes from every caller.

Grill Log

• Q: Should ResourceNotFound be folded into InvalidParams? A: No; it carries the URI as data, which the specification's example shows. _Rejected:_ a string-only invalid-params.

Referenced by

[[src/PuduLangMcp/Errors/_MOC]]