[Feature] mcp-tool-output-collapse

[piromagnus]

Area

Agent core, TUI

Problem

I remarked that the mcp tool called are not collapsed like the refinements tool call.
Could you add this. I have a local update if you want it, i can provide it.

Proposed direction

1. What the fix does (user-visible)

Ctrl+O is bound to app.tools.expand ("Toggle tool output"). interactive-mode.js
toggles setExpanded(bool) on every ToolExecutionComponent — that part always worked.

The bug: for tools without custom renderCall/renderResult renderers — which is
the case for all MCP tools (ctx_execute, ctx_search, ...) — the component falls back
to generic renderers that ignored this.expanded and always printed the FULL tool
output:

• createResultFallback() → new Text(theme.fg("toolOutput", output)) with full output
• formatToolExecution() (used when the tool has no definition at all) → full pretty-JSON
  args + full output

Built-in bash already collapsed properly (see rebuildBashResultRenderComponent in
dist/core/tools/bash.js): last 5 visual lines, ... N earlier lines plus a
(Ctrl+O to expand) hint, cached per render width.

After the patch, MCP tool output behaves the same way:

ctx_execute · done
  ... 45 earlier lines (Ctrl+O to expand)
  output line 46
  output line 47
  output line 48
  output line 49
  output line 50

Expanded (Ctrl+O again) shows the full output, as before. Built-in tool renderers
(bash, edit, ipython, ...) and the panel header logic are untouched.

2. How it works (internals)

Both copies of ToolExecutionComponent (ESM + bundle) receive the same three changes:

a) createResultFallback() — the result fallback used by MCP tools. When
this.expanded is false it now returns a duck-typed "component" object instead of a
Text:

• render(width) lazily truncates the styled output with truncateToVisualLines(styled, 5, width) and caches {lines, skipped, width} in a closure — recomputed only when the
  render width changes.
• If skippedCount > 0, it prepends the hint line:
  ... N earlier lines + expandCollapseHint("app.tools.expand", false) when
  this.showExpandHint, else ... (N earlier lines). The hint line is itself clamped
  with truncateToWidth(hint, width, "...").
• invalidate() clears the width cache.

b) createCollapsedArgsSummary() (new helper) — JSON.stringify(args) on a single
line, clamped to 120 columns via truncateToWidth(..., "..."). Used by
formatToolExecution() when collapsed, replacing the multi-line pretty JSON.

c) formatToolExecution() (no-definition path) — collapsed: emits only the compact
args summary (the output preview component is mounted separately by updateDisplay());
expanded: pretty JSON + full output exactly as before.

Module constants added in both files: RESULT_PREVIEW_LINES = 5,
ARGS_SUMMARY_MAX_WIDTH = 120.

ESM file additionally imports truncateToWidth (from @earendil-works/pi-tui),
expandCollapseHint (./keybinding-hints.js) and truncateToVisualLines
(./visual-truncate.js). The bundle chunk already had all three in scope at its top
(lines ~165/344/345).

Files involved

Copy	File
ESM	dist/modes/interactive/components/tool-execution.js
Bundle	dist/bundle/chunk-<HASH>.js (chunk name changes every release; ctrlo-reapply.py auto-detects it by scanning for var ToolExecutionComponent = class extends Container {)

The bundle does NOT export ToolExecutionComponent, so it cannot be unit-tested
directly; it is kept behaviourally identical to the ESM file (verified by token-level
comparison of the class bodies — only bundler artifacts differ: void 0 vs undefined,
var-class style, minified local param names, escaped unicode, import aliasing).

Alternatives considered

No response

Additional context

No response