chore: import upstream snapshot with attribution

errs/problem.go

@@ -0,0 +1,43 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package errs
+
+// Problem is the RFC 7807-aligned shared shape embedded by every typed error.
+//
+// Message is REQUIRED. Producers must populate it; an empty Message will make
+// Error() return "" — a known Go footgun for fmt.Errorf("...: %v", err).
+//
+// Wire-format notes:
+//   - No Component field. Service / shortcut component is metric-only
+//     enrichment derived by the dispatcher from the cobra command path; it
+//     never appears on the wire.
+//   - No DocURL field. PermissionError carries the same intent via its typed
+//     ConsoleURL extension; other typed errors do not link out.
+//   - Troubleshooter is the upstream Lark API's diagnostic URL (resp.error.
+//     troubleshooter). Carried universally so any classified error can surface
+//     it; populated by errclass.BuildAPIError when the upstream response
+//     includes it, otherwise absent.
+//   - Retryable uses omitempty so only `true` is emitted; consumers treat
+//     absence as false.
+type Problem struct {
+	Category       Category `json:"type"`
+	Subtype        Subtype  `json:"subtype,omitempty"`
+	Code           int      `json:"code,omitempty"`
+	Message        string   `json:"message"`
+	Hint           string   `json:"hint,omitempty"`
+	LogID          string   `json:"log_id,omitempty"`
+	Troubleshooter string   `json:"troubleshooter,omitempty"`
+	Retryable      bool     `json:"retryable,omitempty"`
+}
+
+// Error satisfies the standard `error` interface. A nil receiver is treated
+// as the empty string so a stray nil *Problem stored in an error interface
+// cannot panic the dispatcher.
+func (p *Problem) Error() string {
+	if p == nil {
+		return ""
+	}
+	return p.Message
+}
+func (p *Problem) ProblemDetail() *Problem { return p }