Agent sandbox should fail loudly when workspace tools are unavailable

[chubes4]

Problem

WP Codebox sandbox guidance tells the model to use workspace tools (workspace_read, workspace_ls, workspace_grep, workspace_write, workspace_edit, workspace_apply_patch), but the lab run produced agent replies saying workspace tools were unavailable. The sandbox still returned success and an empty patch.

Evidence from lab run:

• Fanout run: /tmp/homeboy-wp-codebox-audit-bwz45ims/fanout-run.json
• Example record: missing_method
• Example artifact: /tmp/homeboy-wp-codebox-artifacts-pr44ovsz/runtime-mpohjxp3-c85xcu
• Nested agent result was successful/completed from the runtime perspective, but the reply started: I was unable to read the workspace files directly because the workspace tools are not available in this context.
• The artifact had files/patch.diff size 0, so no edit was produced.

Relevant WP Codebox code:

• packages/cli/src/agent-code.ts builds sandbox guidance listing the workspace tools.
• It also sets client_context.tool_contract and tool_policy with the sandbox tool names.
• Despite that, the model did not receive/use executable workspace tools in the real run.

Why this matters

If workspace tools are unavailable, the sandbox should fail before or during the agent run with a structured diagnostic. A text-only "I cannot access tools" answer is not an acceptable successful autofix artifact.

Acceptance criteria

• WP Codebox verifies that requested sandbox workspace tools are registered and visible before starting an agent run.
• The agent runtime result includes a structured diagnostic listing requested, registered, allowed, and missing tools.
• Runs fail or return a non-actionable status when required workspace tools are missing/unavailable.
• The sandbox prompt/tool policy/tool contract uses the same canonical tool names that Data Machine/Data Machine Code exposes.
• Smoke coverage reproduces a missing-tool case and proves it is not reported as successful.

Related

• Data Machine Code companion issue should verify DMC exposes the expected sandbox-safe workspace tools under these names.
• WP Codebox artifact summary issue: Agent sandbox should surface actionable transcript and artifact summaries #172
• Homeboy no-actionable-patch validation: Fail WP Codebox fanout records that produce no actionable patch Extra-Chill/homeboy-extensions#801
• Data Machine XML fallback PR used during the run: Parse XML tool calls from text responses Extra-Chill/data-machine#2307

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Inspected WP Codebox sandbox configuration and lab agent output, then drafted this issue.