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simonpcouchsimonpcouch
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revert client-side http support
Will instead recommend https://www.npmjs.com/package/mcp-remote for more full-featured support
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‎CLAUDE.md‎

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@@ -46,63 +46,3 @@ The server uses a condition variable (`cv`) to coordinate multiple async operati
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- Server dials to `inproc://mcptools-session-1` by default
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- `inproc://` transport is fast for same-machine communication
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- Connections are cleaned up with `nanonext::reap()` on exit
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## HTTP Transport Implementation
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### Current Status
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The HTTP transport implementation follows the "MUSTs only" principle from the MCP specification:
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**Implemented (MUSTs):**
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- HTTP POST endpoint for JSON-RPC messages
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- `MCP-Protocol-Version` header validation
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- Origin validation for DNS rebinding protection
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- Client-side session ID tracking (if server provides `Mcp-Session-Id` header)
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- GET endpoint (returns 405 - SSE streaming not implemented)
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**Not Implemented (MAYs/SHOULDs):**
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- Server-side session management (MAY in spec)
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- SSE streaming for GET requests (optional)
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- OAuth 2.1 authentication (OPTIONAL in spec)
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- HTTPS/TLS support
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### HTTP vs HTTPS
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**Protocol Requirements:**
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- The MCP protocol does NOT require HTTPS for authless HTTP servers
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- HTTPS is only REQUIRED for OAuth/authorization endpoints (which we don't implement)
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**Client Compatibility:**
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- **Claude Code**: Works with `http://` servers ✓
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- **Claude Desktop**: Requires `https://` servers (product policy, not protocol requirement) ✗
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Since HTTPS requires SSL certificates (self-signed for local dev, proper certs for production),
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we defer HTTPS support until OAuth 2.1 is implemented, when it becomes a MUST.
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### Testing with the Inspector
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The MCP inspector helps test MCP servers:
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```bash
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Rscript -e "mcptools::mcp_server(type = 'http', port = 9000)"
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```
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Then:
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```bash
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npx @modelcontextprotocol/inspector --transport http --server-url http://127.0.0.1:9000
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```
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### Using with Claude Code
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Add the HTTP server to Claude Code:
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```bash
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claude mcp add --transport http r-mcptools-http http://127.0.0.1:9000
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```
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Remove it:
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```bash
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claude mcp remove r-mcptools-http
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```

‎NEWS.md‎

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@@ -1,11 +1,9 @@
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# mcptools (development version)
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* `mcp_tools()` now errors more informatively when an MCP server process exits unexpectedly (#82).
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* `mcp_tools()` now errors more informatively when an MCP server process exits unexpectedly (#82).
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* `mcp_server()` now supports HTTP transport in addition to stdio. Use `type = "http"` to start an HTTP server, with optional `host` and `port` arguments. For now, the implementation is authless.
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* `mcp_tools()` now supports connecting to HTTP-based MCP servers. Configure servers with a `url` field in the config file instead of `command`/`args`.
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* JSON-RPC responses now retain an explicit `id = NULL` value, ensuring parse-error replies conform to the MCP specification.
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* `mcp_server()` now formats tool results in the same way as ellmer (#78 by @gadenbuie).

‎R/client.R‎

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Original file line numberDiff line numberDiff line change
@@ -38,12 +38,12 @@ the$mcp_servers <- list()
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#' file with `file.edit(file.path("~", ".config", "mcptools", "config.json"))`.
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#'
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#' The mcptools config file should be valid .json with an entry `mcpServers`.
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#' That entry should contain named elements, each configured for either
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#' **stdio** or **HTTP** transport.
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#' That entry should contain named elements, each with at least a `command`
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#' and `args` entry.
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#'
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#' ## Local servers (via stdio)
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#'
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#' For stdio-based servers, provide `command` and `args` entries:
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#' For example, to configure `mcp_tools()` with GitHub's official MCP Server
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#' <https://github.com/github/github-mcp-server>, you could write the following
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#' in that file:
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#'
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#' ```json
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#' {
@@ -66,23 +66,6 @@ the$mcp_servers <- list()
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#' }
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#' ```
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#'
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#' ## Remote servers (via http)
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#'
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#' For HTTP-based servers, provide a `url` entry instead of `command`/`args`:
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#'
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#' ```json
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#' {
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#' "mcpServers": {
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#' "local-http": {
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#' "url": "https://localhost:8080"
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#' },
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#' "remote-http": {
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#' "url": "https://mcp.example.com/mcp"
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#' }
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#' }
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#' }
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#' ```
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#'
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#' @returns
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#' * `mcp_tools()` returns a list of ellmer tools that can be passed directly
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#' to the `$set_tools()` method of an [ellmer::Chat] object. If the file at
@@ -117,113 +100,33 @@ mcp_tools <- function(config = NULL) {
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for (i in seq_along(config)) {
118101
config_i <- config[[i]]
119102
name_i <- names(config)[i]
120-
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if ("url" %in% names(config_i)) {
122-
add_mcp_server_http(config = config_i, name = name_i)
103+
config_i_env <- if ("env" %in% names(config_i)) {
104+
unlist(config_i$env)
123105
} else {
124-
add_mcp_server_stdio(config = config_i, name = name_i)
106+
NULL
125107
}
126-
}
127-
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servers_as_ellmer_tools()
129-
}
130108

131-
add_mcp_server_stdio <- function(config, name, call = caller_env()) {
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config_env <- if ("env" %in% names(config)) {
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unlist(config$env)
134-
} else {
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NULL
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}
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process <- processx::process$new(
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command = Sys.which(config$command),
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args = config$args %||% character(),
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env = config_env,
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stdin = "|",
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stdout = "|",
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stderr = "|"
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)
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the$server_processes <- c(
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the$server_processes,
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list2(
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!!paste0(
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c(config$command, config$args %||% ""),
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collapse = " "
153-
) := process
109+
process <- processx::process$new(
110+
# seems like the R process has a different PATH than process_exec
111+
command = Sys.which(config_i$command),
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args = config_i$args,
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env = config_i_env,
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stdin = "|",
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stdout = "|",
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stderr = "|"
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)
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)
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# Fail gracefully if the process failed on startup (#82)
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tryCatch(
159-
{
160-
response_initialize <- send_and_receive_stdio(
161-
process,
162-
mcp_request_initialize()
163-
)
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165-
send_and_receive_stdio(process, mcp_request_initialized())
166-
response_tools_list <- send_and_receive_stdio(
167-
process,
168-
mcp_request_tools_list()
119+
the$server_processes <- c(
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the$server_processes,
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list2(
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!!paste0(c(config_i$command, config_i$args), collapse = " ") := process
169123
)
170-
},
171-
error = function(e) {
172-
if (process$get_exit_status() %in% c(1L, 2L)) {
173-
cli::cli_abort(
174-
c(
175-
"The command {.code {config$command}} failed with the following error:",
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"x" = "{paste0(process$read_all_error_lines(), collapse = '. ')}"
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),
178-
call = call
179-
)
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}
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182-
cnd_signal(e)
183-
}
184-
)
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186-
the$mcp_servers[[name]] <- list(
187-
name = name,
188-
type = "stdio",
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process = process,
190-
tools = response_tools_list$result,
191-
id = 3
192-
)
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the$mcp_servers[[name]]
195-
}
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add_mcp_server_http <- function(config, name) {
198-
response_initialize <- send_and_receive_http(
199-
url = config$url,
200-
request = mcp_request_initialize()
201-
)
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203-
session_id <- response_initialize$session_id
204-
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send_and_receive_http(
206-
url = config$url,
207-
request = mcp_request_initialized(),
208-
session_id = session_id
209-
)
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response_tools_list <- send_and_receive_http(
212-
url = config$url,
213-
request = mcp_request_tools_list(),
214-
session_id = session_id
215-
)
124+
)
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217-
the$mcp_servers[[name]] <- list(
218-
name = name,
219-
type = "http",
220-
url = config$url,
221-
session_id = session_id,
222-
tools = response_tools_list$result,
223-
id = 3
224-
)
126+
add_mcp_server(process = process, name = name_i)
127+
}
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226-
the$mcp_servers[[name]]
129+
servers_as_ellmer_tools()
227130
}
228131

229132
mcp_client_config <- function() {
@@ -290,34 +193,19 @@ error_no_mcp_config <- function(call) {
290193
)
291194
}
292195

293-
send_and_receive_http <- function(url, request, session_id = NULL) {
294-
req <- httr2::request(url) |>
295-
httr2::req_method("POST") |>
296-
httr2::req_headers(
297-
"Content-Type" = "application/json",
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"Accept" = "application/json",
299-
"MCP-Protocol-Version" = "2025-06-18"
300-
) |>
301-
httr2::req_body_json(request)
302-
303-
if (!is.null(session_id)) {
304-
req <- httr2::req_headers(req, "Mcp-Session-Id" = session_id)
305-
}
306-
307-
resp <- httr2::req_perform(req)
308-
309-
if (httr2::resp_status(resp) == 202L || httr2::resp_body_string(resp) == "") {
310-
return(NULL)
311-
}
312-
313-
body <- httr2::resp_body_json(resp)
196+
add_mcp_server <- function(process, name) {
197+
response_initialize <- send_and_receive(process, mcp_request_initialize())
198+
send_and_receive(process, mcp_request_initialized())
199+
response_tools_list <- send_and_receive(process, mcp_request_tools_list())
314200

315-
session_id_header <- httr2::resp_header(resp, "Mcp-Session-Id")
316-
if (!is.null(session_id_header)) {
317-
body$session_id <- session_id_header
318-
}
201+
the$mcp_servers[[name]] <- list(
202+
name = name,
203+
process = process,
204+
tools = response_tools_list$result,
205+
id = 3
206+
)
319207

320-
body
208+
the$mcp_servers[[name]]
321209
}
322210

323211
servers_as_ellmer_tools <- function() {
@@ -459,21 +347,13 @@ tool_ref <- function(server, tool, arguments) {
459347
}
460348

461349
call_tool <- function(..., server, tool) {
462-
server_config <- the$mcp_servers[[server]]
463-
464-
request <- mcp_request_tool_call(
465-
id = jsonrpc_id(server),
466-
tool = tool,
467-
arguments = list(...)
468-
)
469-
470-
switch(
471-
server_config$type,
472-
stdio = send_and_receive_stdio(server_config$process, request),
473-
http = send_and_receive_http(
474-
url = server_config$url,
475-
request = request,
476-
session_id = server_config$session_id
350+
server_process <- the$mcp_servers[[server]]$process
351+
send_and_receive(
352+
server_process,
353+
mcp_request_tool_call(
354+
id = jsonrpc_id(server),
355+
tool = tool,
356+
arguments = list(...)
477357
)
478358
)
479359
}
@@ -492,11 +372,13 @@ log_cat_client <- function(x, append = TRUE) {
492372
cat(x, "\n\n", sep = "", append = append, file = log_file)
493373
}
494374

495-
send_and_receive_stdio <- function(process, message) {
375+
send_and_receive <- function(process, message) {
376+
# send the message
496377
json_msg <- jsonlite::toJSON(message, auto_unbox = TRUE)
497378
log_cat_client(c("FROM CLIENT: ", json_msg))
498379
process$write_input(paste0(json_msg, "\n"))
499380

381+
# poll for response
500382
output <- NULL
501383
attempts <- 0
502384
max_attempts <- 20

‎inst/example-config-http.json‎

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This file was deleted.

inst/example-config-stdio.json renamed to inst/example-config.json

File renamed without changes.

‎man/client.Rd‎

Lines changed: 5 additions & 22 deletions
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