deepseek-harness/docs/rfc/proposed/2026-06-20-generic-tool-rendering.md

RFC: Collapse tool-owned UI presentation

Status: proposed

Problem

Tools can define presentCall() and presentResult() callbacks that return ToolCallPresentation, ToolResultPresentation, and optional ToolTerminal fields. The code itself flags the design as muddy: title, kind, raw input, content, terminal cwd, terminal output, exit code, and signal grew incrementally into a bag of optional fields. ACP then maintains pending call state to pair a result with the original args, creates replay-only presenters on session/load, and maps terminal subfields into Zed-specific _meta. dsh-tool-bash even parses exit status back out of rendered text because the pure replay-safe presenter no longer has the structured BashRunResult.

The real first-party use is bash presentation for ACP. That is too little evidence to freeze a cross-package UI presentation API.

Proposal

Remove tool-owned UI presentation callbacks for now. The canonical tool events already carry the tool name, raw argument string, result content, and error state. UIs render a generic tool card from those fields. Tool-specific rich rendering can return later as a tagged render-intent union after there are at least two real tools and two real consumers to validate the vocabulary.

As a smaller alternative, replace the current optional-field bag with one explicit union in a single PR; but if the goal is simplification, the stronger move is to delete the callbacks and keep the generic path.

Acceptance criteria

• ToolDefinition drops presentCall and presentResult.
• ToolCallPresentation, ToolResultPresentation, ToolTerminal, and ToolCallKind disappear unless a minimal generic UI type still needs one.
• ACP no longer keeps presenter pending state or calls tool callbacks during live streaming/load replay.
• dsh-tool-bash no longer parses rendered text to recover exit status for a UI pill.
• Snapshot goldens show generic tool cards and text results.

What we give up

Bash loses its custom terminal-looking card and model-written description placement. The fallback remains reasonable: the command appears as tool input, and the output appears as text. Rich rendering should be designed when the product has enough UI/tool variety to justify a stable presentation contract.

Related

This is the broad version of dropping ACP terminal metadata. If this RFC is accepted, that narrower RFC becomes unnecessary.