#!/usr/bin/env bash
# Capability negotiation helpers.
set -euo pipefail
mcp_spec_supported_protocols() {
# Default protocol 2025-11-25 with explicit back-compat for earlier releases.
printf '%s' "2025-11-25 2025-06-18 2025-03-26 2024-11-05"
}
mcp_spec_resolve_protocol_version() {
local requested="$1"
local version
if [ -z "${requested}" ]; then
printf '%s' "${MCPBASH_PROTOCOL_VERSION}"
return 0
fi
for version in $(mcp_spec_supported_protocols); do
if [ "${requested}" = "${version}" ]; then
printf '%s' "${version}"
return 0
fi
done
return 1
}
mcp_spec_capabilities_full() {
cat <<'EOF'
{"logging":{},"tools":{"listChanged":true},"resources":{"subscribe":true,"listChanged":true},"prompts":{"listChanged":true},"completions":{}}
EOF
}
mcp_spec_capabilities_backport_20250326() {
# Older protocol maintains core surface but omits listChanged flags added in 2025-06-18.
cat <<'EOF'
{"logging":{},"tools":{},"resources":{"subscribe":true},"prompts":{}}
EOF
}
mcp_spec_capabilities_backport_20241105() {
# Legacy protocol support for clients pinned to 2024-11-05; no listChanged flags.
cat <<'EOF'
{"logging":{},"tools":{},"resources":{"subscribe":true},"prompts":{}}
EOF
}
mcp_spec_capabilities_minimal() {
printf '{"logging":{}}'
}
mcp_spec_capabilities_for_runtime() {
local protocol="${1:-${MCPBASH_NEGOTIATED_PROTOCOL_VERSION:-${MCPBASH_PROTOCOL_VERSION}}}"
if mcp_runtime_is_minimal_mode; then
mcp_spec_capabilities_minimal
else
case "${protocol}" in
2025-03-26)
mcp_spec_capabilities_backport_20250326
;;
2024-11-05)
mcp_spec_capabilities_backport_20241105
;;
*)
mcp_spec_capabilities_full
;;
esac
fi
}
mcp_spec_build_initialize_response() {
local id_json="$1"
local capabilities_json="$2"
local protocol="${3:-${MCPBASH_NEGOTIATED_PROTOCOL_VERSION:-${MCPBASH_PROTOCOL_VERSION}}}"
# Build serverInfo with required fields and optional fields when set
local server_info
server_info="$(mcp_spec_build_server_info)"
printf '{"jsonrpc":"2.0","id":%s,"result":{"protocolVersion":"%s","capabilities":%s,"serverInfo":%s}}' \
"${id_json}" \
"${protocol}" \
"${capabilities_json}" \
"${server_info}"
}
mcp_spec_build_server_info() {
# Build serverInfo object with required fields (name, version, title)
# and optional fields (description, icons, websiteUrl) when set.
# If we have JSON tooling, use jq for clean construction
if [ "${MCPBASH_JSON_TOOL:-none}" != "none" ]; then
local jq_args=()
jq_args+=(--arg name "${MCPBASH_SERVER_NAME}")
jq_args+=(--arg version "${MCPBASH_SERVER_VERSION}")
jq_args+=(--arg title "${MCPBASH_SERVER_TITLE}")
local jq_filter='{name: $name, version: $version, title: $title}'
# Add optional fields
if [ -n "${MCPBASH_SERVER_DESCRIPTION:-}" ]; then
jq_args+=(--arg description "${MCPBASH_SERVER_DESCRIPTION}")
jq_filter="${jq_filter} + {description: \$description}"
fi
if [ -n "${MCPBASH_SERVER_WEBSITE_URL:-}" ]; then
jq_args+=(--arg websiteUrl "${MCPBASH_SERVER_WEBSITE_URL}")
jq_filter="${jq_filter} + {websiteUrl: \$websiteUrl}"
fi
if [ -n "${MCPBASH_SERVER_ICONS:-}" ]; then
jq_args+=(--argjson icons "${MCPBASH_SERVER_ICONS}")
jq_filter="${jq_filter} + {icons: \$icons}"
fi
"${MCPBASH_JSON_TOOL_BIN}" -c -n "${jq_args[@]}" "${jq_filter}"
else
# Minimal mode: construct JSON using local escaping helpers.
# mcp_json_quote_text does not depend on jq/gojq.
local name_json version_json title_json
name_json="$(mcp_json_quote_text "${MCPBASH_SERVER_NAME}")"
version_json="$(mcp_json_quote_text "${MCPBASH_SERVER_VERSION}")"
title_json="$(mcp_json_quote_text "${MCPBASH_SERVER_TITLE}")"
printf '{"name":%s,"version":%s,"title":%s}' \
"${name_json}" \
"${version_json}" \
"${title_json}"
fi
}
