A task held as machine busy shows no reason; max_load changes need a restart #1579

Seen on: dev 837b2b0.

Behaviour

A task held by the busy-machine gate sits under Waiting 1 ▸ on the rail with no reason (at 215 columns), and the task page read queued · 10m 47s with no reason, while no model call is made for minutes. The manual promises waiting · machine busy · load per core at or above task.max_load 1.5. Also, changing task.max_load does not free a held task until the engine restarts.

Replication

1. Build dev 837b2b0 (git checkout 837b2b0 && make build), or install the dev build with curl -fsSL https://agentfield.ai/get/devaf | bash.
2. Use an isolated profile: export HOME=$(mktemp -d), export OPENROUTER_API_KEY, default model.
3. Leave the busy-machine gate ON (step 5 forces it).
4. cd $(mktemp -d) && git init -q && codeaf.
5. Force the hold: set task.max_load below the current load per core (for example 0.01) in /settings.
6. /task add a README.md with one line. Read the rail row and the task page.
7. Set task.max_load back to 0: the task stays held until codeaf engine --stop and a relaunch.

Evidence

• Rail: Waiting 1 ▸ with no reason; task page queued · 10m 47s.
• internal/session/task_pressure.go:249-267 builds the machine busy reason words; internal/tui3/task.go:780 (waitWordMachine), internal/tui3/room.go:3298-3302 and internal/tui3/tasksplace.go:1891 draw railParked words only.
• internal/session/task_run.go:1264: the governor is built once from a.config.TaskMaxLoad when the graph is made.

Guessed cause

A guess from reading the code, not a confirmed diagnosis. The rail renders the railParked group without status.Reason, and the admission governor reads task.max_load once, so a changed setting does not reach it.

Acceptance

• e2e: with the hold forced, the rail row and the task page both read waiting · machine busy · load per core at or above task.max_load ….
• e2e: setting task.max_load to 0 in /settings admits the held task within a few seconds, with no restart.

Found while writing the public docs; manual text differences are in #1545.

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