lms log stream

lms log stream lets you inspect the exact strings LM Studio sends to and receives from models, and (new in 0.3.26) stream server logs. This is useful for debugging prompt templates, model IO, and server operations.

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Quick start (model input)

By default, lms log stream shows the formatted user message that is sent to the model:

lms log stream

Send a message in Chat or call the local HTTP API to see logs.

Choose a source

Use --source to select which logs to stream:

• --source model (default) — model IO
• --source server — HTTP API server logs (startup, endpoints, status)

Example (server logs):

lms log stream --source server

Filter model logs

When streaming --source model, filter by direction:

• --filter input — formatted user message sent to the model
• --filter output — model output (printed after completion)
• --filter input,output — both user input and model output

Examples:

# Only the formatted user input
lms log stream --source model --filter input

# Only the model output (emitted once the message completes)
lms log stream --source model --filter output

# Both directions
lms log stream --source model --filter input,output

Note: model output is queued and printed once the message completes.

JSON output and stats

• Append --json to emit machine‑readable JSON logs:

lms log stream --source model --filter input,output --json

• Append --stats (model source) to include tokens/sec and related metrics:

lms log stream --source model --filter output --stats

Example (model input and output)

$ lms log stream --source model --filter input,output
Streaming logs from LM Studio

timestamp: 9/15/2025, 3:16:39 PM
type: llm.prediction.input
modelIdentifier: gpt-oss-20b-mlx
modelPath: lmstudio-community/gpt-oss-20b-mlx-8bit
input:
<|start|>system<|message|>...<|end|><|start|>user<|message|>hello<|end|><|start|>assistant

timestamp: 9/15/2025, 3:16:40 PM
type: llm.prediction.output
modelIdentifier: gpt-oss-20b-mlx
output:
Hello! 👋 How can I assist you today?