pi-tool-display

OpenCode-style tool rendering for the Pi coding agent.

pi-tool-display keeps tool calls compact by default, adds richer diff rendering for file edits, and improves a few core chat UI details such as thinking labels and the native user prompt box.

Features

• Compact built-in tool rendering for read, grep, find, ls, bash, edit, and write
• MCP-aware rendering with hidden, summary, and preview modes
• Opt-in custom tool overrides for noisy extension tools, defaulting to generic rendering unless kind: "mcp" is selected
• Adaptive edit/write diffs with split or unified layouts, syntax highlighting, inline emphasis, and narrow-pane width clamping
• Workspace-scoped projected pending edit/write previews that show pending edit, pending overwrite, and pending create diffs while partial tool calls are still streaming
• Progressive collapsed diff hints that shorten automatically on small terminal widths instead of overflowing
• Hashline-anchor diff gutters that preserve LINE#HASH labels from anchored read/edit output when those lines are rendered in diffs
• Three presets: opencode, balanced, and verbose
• Thinking labels during streaming and final message rendering, with context sanitization to avoid leaking presentation labels back into future model turns
• Optional native user message box with markdown-aware rendering and safer ANSI/background handling
• Per-tool ownership toggles so this extension can coexist with other renderer extensions
• Capability-aware settings that keep MCP and RTK-specific controls aligned with the current environment
• Adapter API for renderer consumers through the pi-tool-display/tool-display-api-consumer subpath export

Installation

Local extension folder

Place this folder in one of Pi's auto-discovery locations:

# Global default (when PI_CODING_AGENT_DIR is unset)
~/.pi/agent/extensions/pi-tool-display

# Project-specific
.pi/extensions/pi-tool-display

npm package

pi install npm:pi-tool-display

Git repository

pi install git:github.com/MasuRii/pi-tool-display

Usage

Interactive settings

Open the settings modal:

/tool-display

The modal exposes the day-to-day controls most people change regularly:

• preset profile
• read output mode
• grep/find/ls output mode
• MCP output mode (when MCP is available)
• preview line count
• bash collapsed line count
• diff layout mode
• native user message box toggle

Advanced options remain in config.json.

Direct commands

/tool-display show                    # Show the effective config summary
/tool-display reset                   # Reset to the default opencode preset
/tool-display preset opencode         # Apply opencode preset
/tool-display preset balanced         # Apply balanced preset
/tool-display preset verbose          # Apply verbose preset

Tool display adapter API

Other extensions can opt into pi-tool-display rendering without directly depending on its load order by importing the consumer helper:

import { decorateToolForDisplay, decorateMcpToolForDisplay } from "pi-tool-display/tool-display-api-consumer";

decorateToolForDisplay(tool, adapter) applies the runtime decoration immediately when pi-tool-display is loaded, or queues the decoration until the API becomes available. Use adapter options such as kind: "read" | "edit" | "mcp" | "generic" to select the renderer family; decorateMcpToolForDisplay(tool) is the shortcut for MCP-style tools.

Presets

Preset	Read Output	Search Output	MCP Output	Bash Output	Preview Lines	Bash Lines
opencode	hidden	hidden	hidden	opencode	8	10
balanced	summary	count	summary	summary	8	10
verbose	preview	preview	preview	preview	12	20

• opencode (default): minimal inline-only display; tool results stay collapsed
• balanced: compact summaries with line counts and match totals; bash shows line count only
• verbose: larger previews for read/search/MCP/bash output

Bash Output Modes

Mode	Behavior
opencode	Classic collapsed output using bashCollapsedLines limit with expansion hint
summary	Shows only line count (e.g., "↳ 3 lines returned") — no output displayed
preview	Shows actual output lines using previewLines limit

Configuration

Runtime configuration is stored at:

Default global path: ~/.pi/agent/extensions/pi-tool-display/config.json
Actual global path: $PI_CODING_AGENT_DIR/extensions/pi-tool-display/config.json when PI_CODING_AGENT_DIR is set

A starter template is included at config/config.example.json.

Configuration options

Option	Type	Default	Description
debug	boolean	false	Opt-in file logging for extension diagnostics; missing values are treated as false
registerToolOverrides	object	all true	Built-in tool ownership flags
customToolOverrides	object	{}	Explicit opt-in rendering rules for non-built-in extension tools
enableNativeUserMessageBox	boolean	true	Enable bordered user prompt rendering
readOutputMode	string	"hidden"	hidden, summary, or preview
searchOutputMode	string	"hidden"	hidden, count, or preview
mcpOutputMode	string	"hidden"	hidden, summary, or preview
previewLines	number	8	Lines shown in collapsed preview mode
expandedPreviewMaxLines	number	4000	Max preview lines when fully expanded
bashOutputMode	string	"opencode"	opencode (collapse), summary (line count), or preview (show lines)
bashCollapsedLines	number	10	Lines shown for collapsed bash output (opencode mode)
diffViewMode	string	"auto"	auto, split, or unified
diffIndicatorMode	string	"bars"	bars (vertical indicators), classic (+/- markers), or none
diffSplitMinWidth	number	120	Minimum width before auto mode prefers split diffs
diffCollapsedLines	number	24	Diff lines shown before collapsing
diffWordWrap	boolean	true	Wrap long diff lines when needed
showTruncationHints	boolean	false	Show truncation indicators for compacted output
showRtkCompactionHints	boolean	false	Show RTK compaction hints when RTK metadata exists

Tool ownership

Use registerToolOverrides to control which built-in tools this extension owns:

{
  "registerToolOverrides": {
    "read": true,
    "grep": true,
    "find": true,
    "ls": true,
    "bash": true,
    "edit": true,
    "write": true
  }
}

Set any entry to false if another extension should handle that tool instead.

Changes to tool ownership take effect after /reload.

Custom tool overrides

Use customToolOverrides when another extension registers a noisy top-level tool and you want pi-tool-display to render that tool's call/result output. Custom overrides are explicit opt-in only: unlisted or disabled tools keep their original renderers.

{
  "customToolOverrides": {
    "ide_find_symbol": {
      "enabled": true,
      "kind": "generic",
      "outputMode": "summary"
    },
    "custom_mcp_gateway": {
      "enabled": true,
      "kind": "mcp",
      "outputMode": "preview"
    }
  }
}

Each entry supports:

Field	Type	Default	Description
enabled	boolean	true	Whether pi-tool-display should decorate this custom tool
kind	string	"generic"	generic for plain compact output, or mcp for MCP-style call labels and result handling
outputMode	string	"summary"	hidden, summary, or preview for this custom tool's result output

Boolean shorthand is also accepted:

{
  "customToolOverrides": {
    "ide_find_symbol": true,
    "noisy_tool_to_leave_alone": false
  }
}

Notes:

• Built-in tool names (read, grep, find, ls, bash, edit, write) are ignored here; use registerToolOverrides for those.
• generic call rendering shows the tool name and argument count, then compacts the result according to outputMode.
• mcp call rendering understands MCP proxy-style arguments such as tool, server, search, describe, and connect.
• Changes for already-registered tools take effect after /reload; tools registered later can be decorated as they register.

Example config

{
  "debug": false,
  "registerToolOverrides": {
    "read": true,
    "grep": true,
    "find": true,
    "ls": true,
    "bash": true,
    "edit": true,
    "write": true
  },
  "customToolOverrides": {
    "ide_find_symbol": {
      "enabled": true,
      "kind": "generic",
      "outputMode": "summary"
    },
    "custom_mcp_gateway": {
      "enabled": true,
      "kind": "mcp",
      "outputMode": "preview"
    }
  },
  "enableNativeUserMessageBox": true,
  "readOutputMode": "summary",
  "searchOutputMode": "count",
  "mcpOutputMode": "summary",
  "previewLines": 12,
  "expandedPreviewMaxLines": 4000,
  "bashOutputMode": "opencode",
  "bashCollapsedLines": 15,
  "diffViewMode": "auto",
  "diffIndicatorMode": "bars",
  "diffSplitMinWidth": 120,
  "diffCollapsedLines": 24,
  "diffWordWrap": true,
  "showTruncationHints": false,
  "showRtkCompactionHints": false
}

Debug logging

Debug logging is disabled by default. Set debug to true in the extension root config.json only when collecting diagnostics; missing or non-true values are treated as false. When enabled, diagnostics are appended to debug/debug.log under a runtime-created debug/ directory, and no debug output is written to the terminal.

Rendering notes

Edit and write diffs

edit and write results use the same diff renderer. In auto mode the extension chooses split or unified layout based on available width. On narrow panes it clamps rendered lines and shortens collapsed hint text so the diff stays readable instead of spilling past the terminal width.

While tool arguments are still streaming, partial edit and write calls can show projected pending previews. Deterministic edits render as pending edit diffs against current file contents, writes render as pending overwrite or pending create, and unresolved projections show a clear preview notice instead of guessing. Preview file reads are scoped to the active workspace so pending previews avoid reading paths outside the current project.

When diff input includes Pi anchored read lines such as 12#AB:content, the renderer treats the anchor as line metadata and displays the LINE#HASH label in the gutter while keeping the content aligned for split, unified, and compact diff layouts.

Write summaries

When content is available, write call summaries include line count and byte size information inline so you can quickly see the size of the pending write before expanding the result.

Thinking labels

Thinking blocks are labeled during streaming and on final messages. Before the next model turn, the extension sanitizes those presentation labels out of the stored assistant context so they do not accumulate or pollute future prompts.

Native user message box

When enabled, user prompts render inside a bordered box using Pi's native user message component. The renderer preserves markdown content more safely and normalizes ANSI/background handling to avoid odd nested background artifacts.

Capability detection

The extension checks the current Pi environment and adjusts behavior automatically:

• MCP tooling unavailable at startup: MCP settings can be hidden from the modal, but the configured MCP output mode is preserved because MCP tools may register later
• RTK optimizer unavailable: RTK hint settings are hidden and RTK compaction hints are disabled

This keeps the UI aligned with the current environment while still allowing dynamically registered MCP tools to be styled when they appear.

Troubleshooting

Reload safety

/reload is fully supported. On reload, the extension cleans up all tool overrides, prototype patches, timers, and event handlers through its built-in disposal registry, then re-registers everything on the next session lifecycle event. No manual cleanup is needed.

Tool ownership conflicts

If another extension is already rendering one of the built-in tools:

1. Set registerToolOverrides.<tool> to false
2. Run /reload
3. Use /tool-display show to confirm the effective ownership state

Built-in tool overrides (including bash) are registered with deferred ownership discovery — the extension discovers which tools it owns via pi.getAllTools() during before_agent_start before overriding, preventing conflicts with other extensions that also register overrides.

Config not loading

If your settings are not being applied:

1. Check that the global Pi tool-display config exists (default: ~/.pi/agent/extensions/pi-tool-display/config.json, respects PI_CODING_AGENT_DIR)
2. Make sure the JSON is valid
3. Run /tool-display show to inspect the effective config summary

MCP or custom tool rendering not appearing

MCP tools are decorated via pi.registerTool interception, so they are captured as soon as they register regardless of lifecycle event ordering. If MCP tools still appear unstyled, check that the tool's name or parameter schema matches one of the supported MCP detection heuristics (names containing mcp, server:, ctx_, or parameter schemas with mcpServer/serverUrl/server_name).

For non-MCP extension tools, or MCP-like tools that do not match the heuristics, add the exact tool name under customToolOverrides and run /reload. Use kind: "generic" for ordinary tools and kind: "mcp" for MCP proxy-style arguments.

MCP or RTK settings missing

Those controls only appear when the corresponding capability is available in the current Pi environment.

Project structure

pi-tool-display/
├── index.ts                         # Extension entrypoint for Pi auto-discovery
├── src/
│   ├── index.ts                     # Bootstrap and extension registration
│   ├── capabilities.ts              # MCP/RTK capability detection
│   ├── config-modal.ts              # /tool-display settings UI and command handling
│   ├── config-store.ts              # Config load/save and normalization
│   ├── disposable.ts                # Reload-safe cleanup registry for tool overrides, patches, and timers
│   ├── diff-renderer.ts             # Edit/write diff rendering engine
│   ├── line-width-safety.ts         # Width clamping helpers for narrow panes
│   ├── pending-diff-preview.ts      # Partial edit/write preview projection helpers
│   ├── presets.ts                   # Preset definitions and matching
│   ├── render-utils.ts              # Shared rendering helpers
│   ├── thinking-label.ts            # Thinking label formatting and context sanitization
│   ├── tool-overrides.ts            # Built-in, MCP, and opt-in custom renderer overrides
│   ├── types.ts                     # Shared config and type definitions
│   ├── user-message-box-markdown.ts # Markdown extraction for user message rendering
│   ├── user-message-box-native.ts   # Native user message box registration
│   ├── user-message-box-patch.ts    # Safe native render patching helpers
│   ├── user-message-box-renderer.ts # User message border renderer
│   ├── user-message-box-utils.ts    # ANSI/background normalization helpers
│   ├── write-display-utils.ts       # Write summary helpers
│   └── zellij-modal.ts              # Modal UI primitives
├── config/
│   └── config.example.json          # Starter config template
└── tests/
    ├── ansi-utils.test.ts           # ANSI utility tests including foreground RGB preservation
    ├── bash-display.test.ts         # Bash display and spinner tests
    ├── capabilities-edge.test.ts    # Capability detection edge cases
    ├── config-modal.test.ts         # Config modal tests
    ├── custom-tool-overrides.test.ts # Opt-in custom tool override tests
    ├── debug-logger-edge.test.ts    # Debug logger edge cases
    ├── diff-renderer-ansi.test.ts   # ANSI/background handling tests for diff rendering
    ├── diff-renderer-edge.test.ts   # Diff renderer edge case tests
    ├── diff-renderer-width.test.ts  # Width and background coverage tests for diff rendering
    ├── index-integration.test.ts    # Integration tests for extension lifecycle
    ├── presets-edge.test.ts         # Preset edge case tests
    ├── reload-behavior.test.ts      # Reload-safe cleanup and re-registration tests
    ├── tool-overrides-config.test.ts    # Tool override config tests
    ├── tool-overrides-registration.test.ts # Tool override registration tests
    └── tool-ui-utils.test.ts        # Utility tests for user message and diff helpers

Development

# Type check
npm run build

# Run tests
npm run test

# Full verification
npm run check

Related Pi Extensions

• pi-image-tools — Image attachment and inline preview for the Pi TUI
• pi-hide-messages — Hide older chat messages without losing context
• pi-startup-redraw-fix — Fix terminal redraw glitches on startup
• pi-permission-system — Permission enforcement for tool and command access

License

MIT