feat(bench): add terminal-bench container executor

[drewstone]

Summary

• add a Terminal-Bench container executor that runs spawned workers inside the grader-owned Docker container
• add an offline executor test with a fake Docker binary for argv, metering, and non-zero exit behavior
• add a manual coordination-MCP container reachability probe

Verification

• pnpm exec tsx bench/src/tb-container-executor.test.mts
• pnpm exec tsx bench/src/coordination-mcp-container-reach.mts (Docker 29.2.1; container saw spawn_agent + await_event)
• pnpm run typecheck
• pnpm run lint
• pnpm run build
• pnpm test: 127 files passed, 1,254 tests passed, 2 skipped
• pnpm run verify:package
• git merge-tree --write-tree origin/main HEAD

[tangletools]

✅ Auto-approved drewstone PR — d95246c1

This PR was opened by the trusted drewstone account.
The full PR reviewer audit still runs separately and will publish findings if it detects issues.

_{tangletools · auto-approval · reason: drewstone_author · 2026-07-07T23:43:00Z}

[tangletools]

⚪ Value Audit — audit-incomplete

Verdict	audit-incomplete
Concerns	1 (1 low)
Heuristic	0.0s
Duplication	0.0s
Interrogation	7.2s (2 bridge agents)
Total	7.2s

💰 Value — error

value agent produced no parseable value-audit JSON.

• Model: opencode/deepseek/deepseek-v4-pro
• Bridge attempts: 3
• Bridge error: opencode/kimi-for-coding/k2p7: bridge stream ended without value-audit content; opencode/zai-coding-plan/glm-5.2: bridge stream ended without value-audit content; opencode/deepseek/deepseek-v4-pro: bridge stream ended without value-audit content

🎯 Usefulness — error

usefulness agent produced no parseable value-audit JSON.

• Model: opencode/deepseek/deepseek-v4-pro
• Bridge attempts: 3
• Bridge error: opencode/zai-coding-plan/glm-5.2: bridge stream ended without value-audit content; opencode/kimi-for-coding/k2p7: bridge stream ended without value-audit content; opencode/deepseek/deepseek-v4-pro: bridge stream ended without value-audit content

🔎 Heuristic Signals

🟡 Cruft: console debug added bench/src/coordination-mcp-container-reach.mts

• console.log(

---

What this audit checks

It judges the change on its merits — not whether it was tasked out in an issue. Unticketed, fast-moving work is fine; the question is whether the change is good and whether a better or existing approach should be used instead.

Pass	What it asks
Heuristic	Vague title? Whitespace-only or cruft-bearing diff? (content signals only)
Duplication	Do added function/class names already exist elsewhere in the repo?
Value Audit	What does it do? What goal does it achieve? Is it good? Better architecture or already-exists?
Usefulness Audit	Does it integrate and fit? Will it hold up in real use and actually get used?

Findings are concerns, not blocks — the human reviewer decides what to do with them.

_{value-audit · 20260707T234450Z}

[tangletools]

✅ Auto-approved drewstone PR — f9d3eb4b

This PR was opened by the trusted drewstone account.
The full PR reviewer audit still runs separately and will publish findings if it detects issues.

_{tangletools · auto-approval · reason: drewstone_author · 2026-07-07T23:45:54Z}