Troubleshooting

Most issues fall into a handful of well-known categories. If you don't see your problem here, also check the general troubleshooting guide.

/login browser didn't open

The REPL prints the auth URL — open it manually in any browser, complete the sign-in flow, and the REPL will pick up the token automatically.

/build fails with west: unknown command 'build'

The nRF Connect SDK isn't on the PATH or ZEPHYR_BASE isn't set.

• Install the nRF Connect SDK, or
• Set ZEPHYR_BASE to your nCS zephyr/ directory.

fwm auto-detects common install paths (/opt/nordic/ncs/, ~/ncs/). For non-standard locations, add a custom build command to .fwm/project.toml:

[build]
command = "/path/to/west build -b nrf52840dk/nrf52840"

See Configuration for the full file format.

/flash says "No build output found"

Run /build first — /flash verifies that a build artifact exists before invoking the runner.

Agent runs for a long time

Press Esc. Long-running child processes (builds, flashes, validation shell commands) are killed along with the agent.

Context usage too high

/context        # show current context-window usage
/clear          # reset the conversation pane

If you want to start completely fresh and skip session restore:

fwm agent --no-history

Approving every tool call gets tedious

When a tool-approval prompt appears, press A to accept all remaining calls for the current turn. See Tool-use approval for the full prompt reference.

I want to review changes before they're written

Launch the REPL in plan mode:

fwm agent --plan

The agent will read, reason, and produce a plan — no writes happen until you approve. See Agent Modes.