RCH — Remote Compilation Helper

rch transparently offloads compilation commands to remote workers via a Claude Code PreToolUse hook. The daemon picks the fastest healthy worker, rsync's the workspace, runs the build, syncs artifacts back, and exits with the worker's exit code.

This skill is the operational layer agents use when something about that pipeline isn't working — and the much more common case where it thinks it's working but is silently falling back to local execution. The skill is built around a single principle: self-resolve before asking the human. Every recovery path here is one the agent can run on its own.

Don't re-learn the command surface here. rch --help, rch doctor, and the machine surfaces (--json, --schema, --help-json, --capabilities — see MACHINE_INTROSPECTION.md) self-describe every subcommand, flag, and env var. Env-var knobs and config precedence: CONFIGURATION.md. This skill carries the triage doctrine and recovery playbook routing.

Tested against rch v1.0.18; concepts apply to v1.0.16+.

Read This First

When a build feels slow, run one thing:

RCH_VISIBILITY=verbose <your-command> 2>&1 | grep -E '^\[RCH\]'

The summary line is a contract:

If you can't see why offload isn't happening, prove the path works in isolation before doing anything else:

rch exec -- env CARGO_TARGET_DIR="${TMPDIR:-/tmp}/rch_target_$(basename "$PWD")" cargo check --workspace --all-targets

If that prints [RCH] remote <worker> (...), the offload pipeline is healthy. The problem is upstream of rch exec — usually the hook classifier or the agent's invocation form. If it also fails, follow RECOVERY_PLAYBOOKS.md.

Fast Triage Order

Run in this order and stop at the first failing stage:

1. Availability — rch check, rch status --workers --jobs, rch workers probe --all, rch queue
2. Config + socket consistency — rch config show --sources, rch --json config get general.socket_path, rch --json daemon status
3. Hook integration — rch hook status, rch agents status, rch hook install (idempotent)
4. Command classification + path closure — rch diagnose --dry-run "<your-command>"
5. Remote compile proof — the rch exec probe above
6. If sync fails or storage looks bad, inspect the worker directly:

ssh ubuntu@<host> 'df -h / /tmp && free -h && cat /proc/pressure/memory && cat /proc/pressure/io'
ssh ubuntu@<host> 'du -sh /tmp/rch-* /tmp/rch_target_* 2>/dev/null | sort -h'

Always check both / and /tmp on the worker before deciding what to fix. End-to-end verify: rch self-test --all; comprehensive checks: rch doctor (--fix --dry-run previews auto-fixes).

Quick Fixes

Debugging fail-opens: RCH_VISIBILITY=verbose shows the summary line; RCH_LOG_LEVEL=debug surfaces which fail-open path was taken. All other env knobs (priority, env allowlist, SSH keepalives, compression, profiles): rch --help + CONFIGURATION.md + SSH_TUNING.md.

Anti-Asking Rules

These are the questions agents historically ask the human that they should just answer themselves. The answer is in this skill or trivially derivable. Do not ask. Do.

• "Can I restart the daemon?" — Yes. rch daemon restart -y drains in-flight builds gracefully. It's the documented upgrade path.
• "Can I clean up /tmp/rch_target_*?" — If sudo lsof +D <dir> is empty, yes. See DISK_AND_PRESSURE.md. If non-empty, never.
• "Should I fix the chown on the worker?" — If the symptom matches the Permission denied recipe, yes. It's documented.
• "Should I disable an unreachable worker and continue?" — Yes. rch workers disable <id> --reason "..." --drain -y, then proceed with what's healthy.
• "Should I reinstall the hook?" — If rch hook status says missing, yes. rch hook install is idempotent.
• "Should I sync the toolchain to the workers?" — If RCH-E205 or "toolchain missing on X" appears, yes. rch workers sync-toolchain --all.
• "The cooldown is blocking my retry — should I delete it?" — No. Wait auto_start_cooldown_secs. If you really need to bypass, use rch daemon start directly (it's not gated by the hook autostart cooldown).
• "Can I drop the corrupt telemetry db?" — Yes. TELEMETRY_RECOVERY.md. Telemetry is derived data.
• "Should I recover SSH keys from a sibling host?" — If the keys are missing on this host but reachable on another, yes. SSH_KEY_RECOVERY.md Step 3.

When in genuine doubt, capture the escalation packet (Playbook end of RECOVERY_PLAYBOOKS.md) and surface that — not a wall of text — to the human.

Reference Index

Everything below ships in the skill. Read whichever is relevant.

Recognising what's wrong:

• FAIL_OPEN.md — every [RCH] local (...) reason mapped to a self-fix
• ERROR_CODES.md — full RCH-Exxx catalog with skill-doc cross-refs
• TROUBLESHOOTING.md — diagnostic flow + common errors

Solving specific failure classes:

• RECOVERY_PLAYBOOKS.md — symptom → fix in ≤90s, organized as 12 lettered playbooks
• SSH_KEY_RECOVERY.md — when workers.toml references keys this host doesn't have
• PATH_DEPENDENCIES.md — multi-repo workspaces, closure planner, [path_topology]
• DISK_AND_PRESSURE.md — RCH-E210..217 + the sbh handoff
• TELEMETRY_RECOVERY.md — corrupt ~/.local/share/rch/telemetry/telemetry.db
• SELF_HEALING.md — autostart cooldown, daemon supervision, [self_healing]
• SSH_TUNING.md — ControlMaster, keepalives, retry classification

Operating in fleets and swarms:

• MULTI_AGENT_CONTENTION.md — TOCTOU, fleet deploy races, autostart cooldown sharing
• OPERATIONS.md — full runbook + worker fleet lifecycle
• WORKERS.md — worker config, drain/disable/enable, deploy
• CONFIGURATION.md — config precedence, env vars, runtime paths
• HOOKS.md — hook protocol, install, test
• MACHINE_INTROSPECTION.md — --json, --schema, --help-json, --capabilities

Automation scripts (in `scripts/`):

• auto_recover.sh — heuristic, dry-run-by-default fleet recovery
• worker_disk_triage.sh — read-only mount-aware disk report per worker
• protocol_test.sh — directly probe the hook protocol with synthetic input
• multi_agent_safety.sh — flock wrapper for fleet/setup operations
• mine_rch_history.sh — find prior agent sessions that hit a given failure
• diagnose-rch.sh — comprehensive end-to-end diagnostic (the original)

Templates and project docs:

• assets/workers-template.toml
• Source: <https://github.com/Dicklesworthstone/remote_compilation_helper>

Adjacent Skills

• `sbh` — disk-pressure defense for AI coding workloads. Use when RCH-E210/211/215/216 fires.
• `agent-mail` — file reservations and messaging between agents. Use before rch fleet deploy or any worker config edit in a swarm.
• `ntm` / `vibing-with-ntm` — multi-agent tmux orchestration; common parent context for agents that hit rch failures.
• `cass` — search prior agent sessions; the skill ships scripts/mine_rch_history.sh as a fallback when cass index has dead pointers.

Reading Output: TUI vs Hook

rch itself, when invoked with no subcommand, runs in PreToolUse hook mode (reads JSON from stdin, writes JSON to stdout). Don't run bare rch from a terminal expecting help — use rch --help. Bare TUIs are at rch dashboard (terminal) and rch web (browser); both block your session.