R-native agent layer

RbebelM’s low-level API exposes model loading, ChatML turns, events, and tool orchestration. The R-native agent layer builds a small harness on top of those pieces: one session object can be driven from a console loop or from a JSON-RPC server.

The layer is intentionally separate from the core model bindings. The hot path is still BebeLM/Rust inference; the R layer owns session policy, tool metadata, console interaction, and RPC.

Create a session

library(Rbebelm)

model <- bebel_model_load(Sys.getenv("BEBELM_WEIGHTS_FILE"), num_threads = 2)
agent <- bebel_r_agent(
  model,
  allow_eval = FALSE,
  greedy = TRUE,
  max_gen = 128,
  max_think = 16
)
agent
#> <bebelRAgent>
#>   tools: r_objects, r_help, list_files, read_file, grep_files 
#>   history tokens: 98

The default tools are deliberately small:

library(Rbebelm)
tools <- bebel_default_r_tools(allow_eval = FALSE)
bebel_agent_tool_catalog(tools)
#>         name                                       description
#> 1  r_objects     List objects in the configured R environment.
#> 2     r_help Read R help for a topic, optionally in a package.
#> 3 list_files                     List files under a directory.
#> 4  read_file                                 Read a text file.
#> 5 grep_files                       Search text files by regex.

They include R object/documentation inspection and read-only file tools. The r_eval tool is only included when the agent is created with allow_eval = TRUE.

Run a turn

turn <- bebel_r_agent_turn(
  agent,
  "Reply exactly: R agent ready.",
  max_steps = 1,
  on_event = NULL
)
trimws(sub("(?s)^.*</think>\\s*", "", turn$text, perl = TRUE))
#> [1] "R agent ready."

For interactive use, start the console loop:

bebel_r_agent_console(agent)

Or use the one-call launcher, which loads the model and then enters the console:

bebel_r_agent_start(Sys.getenv("BEBELM_WEIGHTS_FILE", "LFM2.5-8B-A1B-Q4_K_M.gguf"))

The package also installs a small helper script in inst/bin:

agent_bin <- system.file("bin/rbebelm-agent", package = "Rbebelm")
system2(agent_bin, "--help")

Console commands include /tools, /r, /rplot, /transcript, /clear, and /quit. The /r command evaluates R directly in the same environment used by the agent’s R tools. For example, /r x <- mtcars creates an object that r_objects() can later see. Visible /r output is capped so large objects do not flood the chat prompt; assign objects or use summaries such as /r str(x) for inspection. In an Rscript terminal, use /rplot plot(mpg ~ cyl, mtcars) to save graphics as PNG files under rbebelm-plots/. The r_eval and r_plot tools are only advertised to the model when the session is created with allow_eval = TRUE. The console prints a compact token/timing stats line after each user turn.

JSON-RPC SDK surface

The same session object can be served over a small JSON-RPC API. This is not an OpenAI-compatible API; it is an SDK surface for controlling the R-native agent. nanonext and jsonlite are optional dependencies used only by this server.

server <- bebel_r_agent_rpc_server(agent, url = "http://127.0.0.1:8080")
server$start()
# ... handle requests ...
server$close()

Supported methods:

• session/info
• tools/list
• session/transcript
• session/clear
• turn

Example request body for POST /rpc:

{"jsonrpc":"2.0","id":1,"method":"turn","params":{"prompt":"List objects in the R session."}}

The console and RPC layers share the same session, transcript, tool catalog, and BebeLM agent state.