deepseek-harness/packages/core/agent-tool-presentation

dsh-agent-tool-presentation

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The row an agent preset carries to say which form of its tools the model sees: native (every schema), code (only run_code plus a generated TypeScript SDK), or both.

Why a row rather than a registry

The tool registry cannot move into a preset. Its consumers are all host-plane — dsh-agent-loop reads its scheduler, dsh-apiproxy reads its presenters to render tool cards, and every tool plugin registers into it — and a service only moves down when all of its consumers move with it.

What a preset can own is the presentation of that registry. ctx.tools.presentAs() declares it for the mounting agent alone, so a Code Mode session runs beside native ones in one process, each seeing its own catalog. The deployment's mode on the dsh-tools row remains the default that agents declaring nothing get.

What it does

native applies immediately. A code mode instead waits for ctx.codeRuntime, which is a host-plane service (dsh-code-runtime-worker-thread): a preset selecting Code Mode against a deployment composing no runtime then holds this row pending, and dsh-agent-presets refuses the mount naming this id. The alternative — applying optimistically — moves the failure to the session's first request, where the operator can act on neither the preset nor the composition.

mode is required rather than defaulted, because a preset without this row already gets the deployment default; an omitted value would mean the row was composed for nothing.

One agent declares one presentation. A second declaration in the same composition is refused rather than merged: two answers to "which form does the model see" is a contradiction, not an override.

Model Experience

Indirectly, through the projection it selects in dsh-tools: code presents run_code plus a generated SDK section and the rule that only run_code may be called directly, native presents every tool schema. The selection also decides what may EXECUTE: under code the registry resolves a model-direct call naming any other tool to UNKNOWN_TOOL, so this row is what keeps the announced surface and the callable surface the same for every agent it covers (executor-collapse note).

KV Cache effect

No direct invalidation; the presentation is fixed when the agent is composed, so its request prefix is stable for the session's life.

Known Limitations and Deferred Work

• The runtime stays host-plane — a preset can select Code Mode but cannot supply the TypeScript runtime it needs; a deployment that composes none can compose no code-mode preset.