Status: Accepted

Adopt the official computer-use seam with a BotHarness-owned provider

BotHarness composes the official @deepseek-ai/dsh-computer-use service and registers exactly one provider from @botharness/computer under the name botharness-computer. The official experimental provider packages are not adopted. The existing application-defined Computer Service stays: it owns the Human-visible lifecycle (probe, start, stop, viewer, export/import), while the official seam owns tool-provider registration. The two are distinct terms: Computer Provider runs the Computer; Computer Tool Provider supplies the tools PersonaBots use on it.

The Computer Tool Provider owns the whole integration. It connects to a pinned Cua Driver inside the Computer container over stdio MCP (docker exec -i … cua-driver mcp), exposes a curated observe/act/verify core of the driver’s catalog, and keeps the rest reachable through progressive discovery (search/describe) instead of loading the catalog into prompts. The driver is pinned by version and checksum, installed outside /config, telemetry and update checks are disabled, and it runs as the container’s desktop user; the container image is pinned by digest. The long-term supply shape is a derived image that bakes the desktop stack and the driver.

The Tool Provider never depends on the container being up when the Host starts: a stopped Computer is a tool-call error the model reports to the Human, never an activation failure. Guidance is registered as a PersonaBot-scope prompt section at the official TOOL_COMPUTER_USE order, and tools are registered only in the session scopes of PersonaBots whose Computer Access is on (ADR-0080).

Why

• The official seam fixes the registration contract — one exclusive provider, no unified action API, no Session broker — so our Consumers (tools, panels, routing) stay stable if DSH evolves. DSH deliberately leaves observation/action workflow, ownership, and Human interaction to the caller, which is exactly the part BotHarness owns.
• Shipping an experimental provider package would put an experimental dependency and a fixed, globally visible tool catalog into every distribution, against the zero-configuration and stability goals for users. The spike also measured that its initial activation failure is terminal for the Host run (entry did not activate, restart required) while our provider must degrade to a clear tool error.
• Neither official provider fits the container: the native one drives the machine running DSH itself (and a crash can take the Host process with it); the MCP one spawns on the Host and cannot express per-PersonaBot access because its tools are global.
• Tool surface: the driver’s full catalog is large and full of near-synonyms; the Cloudflare Code Mode guidance (small fixed tool sets for direct calls, progressive discovery for large catalogs) matches our constraints — curated core, discoverable expansion, never prompt-dumping.

Considered options

• Official cua-driver-mcp provider in the product — rejected: experimental dependency, global unfilterable tool catalog, terminal activation failure.
• Official cua-driver-native provider — rejected: same-process SDK drives the Host machine, not the container; crash blast radius reaches the Host.
• Keep only the application-defined seam — rejected: the official seam exists at our pinned version; deferring migration loses the reserved prompt order and contract for no benefit.
• cua-driver call per action — rejected: per-call process spawn inflates latency and loses session continuity.
• Expose the whole 60-tool catalog — rejected: prompt cost and selection accuracy; a curated core with progressive discovery is the recorded expansion path.

Consequences

• ADR-0050’s application-defined seam is superseded in part: the Computer Service remains, the computer-use registration moves to the official seam.
• Driver pinning, license notices, telemetry defaults, and the checksum-verified install path become maintenance obligations of @botharness/computer; the derived-image bake-in is the recorded follow-up.
• Provider lifecycle must keep Host boot independent of the container; the stopped-container path is a tested tool error.
• If DSH changes the seam, only this provider’s registration and tool wiring change; Consumers (tools, guidance, panels, audit) stay.