Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

authbridge/authlib/listener/httpx/render.go (1)

100-156: ⚡ Quick win

Past review comment properly addressed with robust 3-tier fallback.

The implementation correctly handles the scenarios flagged in the prior review:

• Full frame marshal with data (lines 125-135)
• Minimal frame fallback omitting optional data and using safe id (lines 136-154)
• Constant precomputed payload as final fallback (line 155)

The id marshalability check (lines 140-144) is correct: it tests whether id can be marshaled independently before including it in the minimal frame, falling back to null per JSON-RPC 2.0 §5.1 when the original id is unmarshalable.

Optional observability enhancement: Consider adding structured logging (slog.Warn) when fallback tiers are triggered, to aid production debugging if marshal failures occur. The current implementation prioritizes reliability (always returns valid JSON) over observability, which is a reasonable trade-off for error paths.

🔍 Optional: Add observability for fallback paths

 	}); err == nil {
 		return body
 	}
+	slog.Warn("httpx: MCP rejection full frame marshal failed, retrying minimal", "error", err)
 	// Full frame failed to marshal — retry without optional data, and
 	// keep the original id only if it survives marshaling on its own
 	// (otherwise drop to null per JSON-RPC 2.0 §5.1).
 	safeID := any(nil)
 	if id != nil {
 		if _, err := json.Marshal(id); err == nil {
 			safeID = id
+		} else {
+			slog.Warn("httpx: MCP rejection id unmarshalable, falling back to null", "error", err)
 		}
 	}
 	if body, err := json.Marshal(map[string]any{
 		"jsonrpc": "2.0",
 		"id":      safeID,
 		"error": map[string]any{
 			"code":    jsonRPCServerError,
 			"message": message,
 		},
 	}); err == nil {
 		return body
 	}
+	slog.Error("httpx: MCP rejection minimal frame marshal failed, using constant fallback", "error", err)
 	return mcpRejectionFallback

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@authbridge/authlib/listener/httpx/render.go` around lines 100 - 156, Add
structured warning logs when the MarshalMCPRejectionBody fallback tiers are
exercised: inside MarshalMCPRejectionBody, log a slog.Warn (including the error
value and context) when the initial full-frame json.Marshal fails, and again
when the minimal-frame json.Marshal (or the id marshalability check) fails and
you must return mcpRejectionFallback; include fields like "stage" ("full" or
"minimal"), the jsonRPCServerError constant, and the id type/value where safe to
do so to aid debugging without exposing sensitive payloads.