dev/bench.sh starts without pnpm or the harness native addon, and blames the plugin 42 smoke failures later #2576

Written-by: Chief

core/dev/bench.sh starts a bench without checking the two things it cannot start without, and in both cases the failure surfaces somewhere else.

1. pnpm missing. ensure_profile runs pnpm install with its output sent to /dev/null and its exit code ignored. With no pnpm on PATH the profile ends up with no node_modules, so dsh logs skipping profile bundle "ds-bot": … cannot resolve profile bundle "ds-bot" and the web server answers, but the plugin never loads. node dev/smoke.mjs smoke <port> then fails 17 steps with ENOENT …/bot/state.json, which reads like a plugin bug.

Measured 2026-11-07 05:41Z on this host: dev/bench.sh smoke 3296 8296 reset → dev/bench.sh: 62: pnpm: not found, exit 127 (pnpm is supplied by corepack, not on PATH).

2. Harness native addon missing. When dsh web starts from a deepseek-harness source checkout whose prebuilt system.node is absent, the bench boots and every Bot turn fails:

Cannot find module '…/native/system/packages/linux-arm64/bin/glibc/system.node'
Require stack: - …/native/system/packages/entry/src/flock.ts

bot/logs/diagnostics.jsonl records it once per turn (source: turn), so all 42 smoke steps report a failure and none of them is a plugin bug. The binary ships prebuilt in @deepseek-ai/node-addon-system-linux-arm64@0.1.2 (already installed under core/dev/harness/node_modules by npm run harness), so the fix is a copy — but nothing tells the operator that.

Expected. start refuses to run, before it writes the profile, with a one-line reason and the remedy, and exits non-zero:

• pnpm not on PATH → name it and say corepack pnpm supplies it.
• the native addon for this host (uname -m, glibc vs musl) missing under $DSH_HARNESS/native/system/packages/<platform>/bin/… → name the path it looked for and the package that ships it.
• ensure_profile's install must not hide its failure: capture the output, and on a non-zero exit print it and stop.

Scope. core/dev/ only — bench.sh plus a small Node helper it calls (e.g. core/dev/bench-preflight.mjs) so the check is unit-testable; no plugin code, no core/src/**.

Acceptance.

a) With pnpm off PATH, dev/bench.sh smoke 3296 8296 reset exits non-zero, prints the pnpm line, and leaves no profiles/web behind.
b) With <harness>/native/system/packages/<platform>/bin/<libc>/system.node renamed away, it exits non-zero and names that exact path.
c) On a healthy host the preflight passes and node dev/smoke.mjs smoke <port> still reports all 42 steps passed.
d) A unit test covers the preflight's decision (pass, missing pnpm, missing addon) and fails when the check is removed.